Thursday, May 27, 2010
Despite an overall decline in accidents by airline operators in the last several decades, the general aviation accident rate has not changed as significantly. While it's obvious that those are two different worlds of flying that contribute to that difference, efforts to improve general aviation safety in the last several years haven't had the desired impact. The insurance company Avemco only insures piston aircraft and has embarked on a significant study to determine what can be done to improve general aviation safety. While admittedly that's financially self-serving for them, the preliminary results have lessons to be learned for the GA community.
Given that Avemco has very detailed information on the pilots they insure as well as on the exact nature of claims made, they are in a unique position of having a database that is more comprehensive than what the FAA and NTSB would otherwise have access to in any accident investigation. In addition, the FAA and NTSB databases only have information on accidents while Avemco's database also includes insured pilots who have not filed claims.
Their findings so far have been interesting. First of all, advanced ratings make no difference in the overall risk. It makes no difference in the accident rate by their data if the pilot has an IFR rating vs. VFR rating, or even an ATP certificate. Also, after several hundred flight hours, overall flight time doesn't make a difference either. While recent type experience does make a difference, the overall hours in a pilot's logbook have no influence on the accident rate either. It may be that what one gains in experience from advanced ratings is offset by new risk exposures. As a result, Avemco has focused on the psychology of the pilot as the primary difference between pilots who have accidents and those who don't.
Bill Rhodes, a human behavior specialist retired from the US Air Force Academy, is heading the research effort at the company. Though the work is far from complete, some overall patterns are starting to emerge from an exhaustive analysis of their database.
It seems that overall experience, skill, and level of training are important in preventing minor accidents. Usually these accidents don't meet the NTSB's criteria for reporting, so they don't appear in the federal safety investigation databases. But minor accidents are reported to the insurance company in the form of claims for a variety of incidents from fender-benders on the taxiway to a hard landing. These are typically accidents that are injury and fatality-free and more often than not, the more experienced the pilot regardless of ratings, the lower the minor accident rate.
In major accidents, however, involving injuries, fatalities or an aircraft write-off, the contributing factors are a bit less clear. Considering that on the average 500 people a year are killed in general aviation accidents in the United States means that finding a way to prevent major accidents doesn't just improve safety, it also helps the insurance company's bottom line as those accidents are its priciest claims. It seems that there's no difference between high-time and low-time pilots when it comes to the major accident rate.
Being a human behavior specialist, Rhodes has put a series of pilots through stressful simulator sessions that tax their abilities in an effort to understand the human factors in emergency and complex situations more clearly. It appears that one group of pilots is able to prioritize tasks quickly and effectively in such situations. He also measured physiologic parameters such as heart rate, breathing rate, and changes in speech patterns and this group of pilots were clearly under stress but adapted and handled the stress easily.
The other group of pilots it turns out don't handle stressful situations well. They unnecessarily try to multitask and are unable to filter out what is important and what's not in a given situation. It appears that this group of pilots may also be taking on additional risks that the first group of pilots won't because that first group will make conservative decisions at the outset to minimize their risk exposure.
While this information might seem intuitive, the key in improving general aviation safety lies in finding a way to identify those pilots who are more at risk as well as making risk assessment an important part of general aviation pilot training much in the same way it's universally applied in military flying which boasts a lower accident rate with low-hour pilots operating higher performance aircraft than most general aviation pilots will ever command.
Source: Flying, June 2010. "Left Seat- The Psychology of Safety" by J. Mac McClellan, p8-10.
Tuesday, May 25, 2010
During the early days of the American space program, there were two schools of thought in liquid-fueled rocket design. One group, represented by Werner von Braun and his team of NASA engineers at the Marshall Spaceflight Center, favored rockets with strong internal structures similar to that of monocoque aircraft. The other group, represented by the Atlas missile engineers at Convair, favored rockets with a thin aluminum shell that used pressurization of the tank and its propellants for structural integrity- what was called balloon skin construction.
The Atlas team had already proven their structural technique would work as the Atlas had already entered service as the first American ICBM and it was already being used for space launches from satellites to the manned Mercury program. The main engineers behind the Atlas, Charlie Bossart and Kraft Ehrlicke, were planning a high-energy liquid fueled upper stage that could be used on the Atlas to boost its orbital payload. This was the Centaur upper stage and it would use the first rocket engine to use liquid oxygen and liquid hydrogen- while liquid oxygen was commonly used as an oxidizer, the Centaur and its Pratt & Whitney RL10 rocket engines pioneered the use of liquid hydrogen- it was much colder and tricker to handle, but combined with liquid oxygen it offered a quantum leap in performance.
Early in the Centaur program the USAF was the main customer, but bureaucratic changes and shifts in mission funding requirements led the Centaur program to be transferred from the Air Force to NASA. As a result, the two main schools of thought in liquid-fueled rockets came to clash in 1962.
Von Braun's team offered a more conservative approach that was being incorporated in their work on the Saturn launch vehicle. Von Braun, now being placed in the position of overseeing the Centaur program, sent his structural engineering chief, Willie Mrazek, to San Diego to review the progress on the Centaur program. Convair's engineers by that point had already developed a reputation as being the "unruly wards" of the Marshall Spaceflight Center and while the USAF was willing to push the technological envelope, the safety-minded culture of NASA desired a less risky approach. Mrazek came to Convair in 1962 not terribly pleased with the balloon skin design of the Centaur.
The heads of Convair tried their best to keep Charlie Bossart and Kraft Ehrlicke clear of Mrazek during his visit. During a technical presentation on the Centaur's construction, unbeknown to Mrazek who was seated in the audience, Charlie Bossart managed to sneak into the presentation and took the seat right to Mrazek. As the presentation proceeded, Mrazek was constantly shaking his head and muttering to himself what he thought was wrong with the Centaur's design. By this point, Bossart had had enough despite his explanations to Mrazek (imagine these two men arguing in a loud whisper in the back of an auditorium) and took him outside. Deane Davis, Convair's deputy director for technical control and Ehrlicke's immediate superior, was convinced that Bossart was taking Mrazek outside to settle the score with fisticuffs.
Bossart took Mrazek to the outdoor factory yard where a brand-new Centaur upper stage sat, its polished thin aluminum skin gleaming in the sunlight. "What's inside it?" asked Mrazek. "Just nitrogen" replied Bossart, at which point he handed Mrazek a hammer and invited him to pound a hole into the side of the Centaur. Without the nitrogen pressurization, the Centaur would collapse under its own weight. Mrazek couldn't believe that gaseous nitrogen was keeping the Centaur's structure, so he took a swing at the rocket stage. The first hit was only a glancing blow and hardly scratched it. I can only picture Bossart at this point egging Mrazek on to hit it harder- which he did. The hammer rebounded off the skin and hit Mrazek in the face, knocking his glasses off. Again, the skin remained unscathed.
Bossart's point was made at the expense of Mrazek's ego and his glasses. The Centaur program proceeded onward from that day in 1962, and the Centaur is still in use today as a second stage on launch vehicles like the Atlas V. It was successfully used on the Titan series of launch vehicles and is currently under consideration as a high-energy upper stage on the new Delta IV rocket.
Source: To Reach the High Frontier- A History of US Launch Vehicles, edited by Roger D. Launius and Dennis Jenkins. The University Press of Kentucky, 2002, p344-345.
Monday, May 24, 2010
From yesterday's Taylor Aerocar to today's Terrafugia, designers and engineers have always dreamed of ways to combining the speed and convenience of flight with the ease and familiarity of automobile travel. Nearly all of the designs that have reached flight hardware status have involved custom-built cars combined with custom-built wings and empennages for flight. But one aeronautical engineer in 1968 dared to think differently and went with an off-the-shelf solution for both components that he was sure would make the flying car practical.
Henry Smolinksi earned his engineering degree from the Northrop Institute of Technology and had devoted a considerable part of his career working with North American Aviation and later, on Rocketdyne. In 1968 he founded his own design firm, Advanced Vehicle Engineers (AVE) based at Van Nuys Airport in southern California to bring his flying car ideas to the forefront. Rather than develop the car and aircraft components anew, Smolinksi thought it would be easier and more economical to use the wings, rear engine and twin tail booms from a Cessna 337 Skymaster mated to special fittings that could be adapted to just about any suitably light consumer automobile. For his prototype, Smolinski chose the Ford Pinto, a lightweight and inexpensive compact car.
Smolinski named his flying car the AVE Mizar, after the binary star in the handle of the Big Dipper. He forecast that it would be ready for the general sales by 1974 and would cost less than $30,000, much less than any general aviation single available in those days. Smolinski brought aboard Hal Blake as the VP of AVE and Bert Boeckmann, a lead salesman in a local southern California Ford dealership, to be responsible more the sale, marketing and distribution of the AVE Mizar via Ford dealers nationwide.
The Pinto had its dash modified to accommodate flight instrumentation and the steering column was also modified to also function as a control yoke as well as a conventional steering wheel. Retractable rudder pedals were also added that folded out of the way to provide access to the brake and gas pedal when in car mode. A set of self-guiding rails were installed on the roof of the Pinto and in effect, the car would be backed up into the the former Skymaster components. In the AVE Mizar prototype, the control linkages ran underneath the car and wing struts fitted into the slots on the lower door sill to support the wings. According to Smolinski, the Mizar would cruise at 13o mph with a maximum speed of 150 mph and a range of 500 miles. Take off roll was only 500 feet as was the landing roll- the car's engine could be used during takeoff to increase the acceleration of the Mizar and the car's brakes were used to shorten the landing run. He estimated that about 55 different production vehicles would be suitable for modification as the former Skymaster components could lift a car with a maximum weight of 3,800 pounds.
The AVE Mizar was formally unveiled at Van Nuys Airport on 9 May 1973. To demonstrate the ease of use, AVE's team planned to use women as test pilots. Taxi tests began in August at Oxnard Airport in Ventura County. By the time of its first flights, AVE had invested $2 million into the design and the first several flights were successful. On 11 September 1973, Smolinkski and Blake took off in the Mizar with Smolinski in the left seat. Climbing through 400 feet, the right wing strut broke free and the right wing folded on itself, sending the Mizar crashing to the ground, instantly killing AVE's president and vice-president. The NTSB's investigation revealed a faulty weld where the right wing strut joined its fitting in the lower right door sill.
The future of the Mizar died in that crash and the flying Pinto was faded into history as another aeronautical curiosity. There is a good website devoted the AVE Mizar at www.cookieboystoys.com/mizar.htm. Highly recommended for a full dose of avgeekiness!
Source: Air & Space Smithsonian, July 2010. "Oldies and Oddities- A Different Kind of Hybrid" by Peter Garrison, p18.
Saturday, May 22, 2010
As early as 1957 NACA (NASA's predecessor) was already conducting lifting body research started by Dr. Alfred Eggers of the Ames Research Laboratory. His pioneering work on lifting body applications to re-entry vehicles for spacecraft and missiles led the US Air Force to initiate START- Spacecraft Technology and Advanced Reentry Test. By 1960 Dr. Eggers' work was taken up by several aerospace firms, most notably Martin Aircraft and Northrop to a lesser extent. Within two years, Martin's engineers had come up with their own designs for a reentry vehicle based on a lifting body design. The USAF considered the Martin designs to be possible foundations for either a maneuverable ICBM warhead that could evade Soviet anti-ballistic missile defenses or for a data/film return vehicle for a spy satellite that could maneuver on reentry to a more favorable recovery point. At the time, the first of the Corona spy satellites were operational and used a ballistic reentry capsule to return the film images to Earth. The timing of the return had to coincide with a point in the Corona's orbit that the capsule would hit a predesignated recovery point. A maneuverable lifting body capsule could be ejected on short notice from less favorable orbits and be maneuvered to a recovery point.
In August of 1964 Martin got the contract for the SV-5D PRIME (Precision Recovery Including Maneuvering Entry). Interestingly, it was assigned the X-23 designation after the completion of the program. Research work by USAF historians demonstrated that all contemporary documents of the day used the SV-5D designation.
Only about six and a half feet in length, the X-23/SV-5D had the same lifting body configuration as the later manned Martin X-24 aircraft. With a lightweight and high-temperature tolerant structure of titanium and beryllium, the craft with three types of ablative silcon and carbon-based heat shielding depending upon the expected maximum temperatures on various parts of the vehicle. The centrally-located equipment bay housed the guidance system, telemetry and data units and the recovery parachute system. The equipment bay was surrounded by a cold-wicking system- two plates surrounded a fluid-filled absorbent material. As the heat built up during reentry, the fluid slowly boiled off and was vented overboard as steam.
The only propulsion on the vehicle was a gas jet thruster system for exo-atmospheric maneuvering as well as body flaps for endo-atmospheric maneuvering. The X-23/SV-5D was carried aloft on an Atlas missile launched from Vandenberg AFB in California. Once the Atlas reached apogee, the nose shrouds were jettisoned and the X-23/SV-5D was released to begin its reentry maneuvers.
The first X-23/SV-5D was launched on 12 December 1966 but only pitch maneuvers were demonstrated. However, the recovery system failed at the end of the 30-minute mission and the first vehicle was lost in the Pacific. The second test took place on 5 March 1967 and during reentry at hypersonic speeds, the X-23/SV-5D maneuvered as much as 500 miles on each side of a ballistic reentry path, proving for the first time the work of Dr. Eggers and Martin Aircraft. Unfortunately, it too was lost in the Pacific when it came loose from its flotation collar and sank. The third and last flight took place on 18 April 1967 and the vehicle performed a full series of test maneuvers and was successfully recovered in midair near Kwajalein Island by a Lockheed JC-130B Hercules. The successful recovery of the third X-23/SV-5D allowed NASA and Martin engineers to study the effects of reentry on the different heat shield materials used on the craft. Due to the success of the third test and the partial results from the failed second test, the fourth X-23/SV-5D was never flown.
At one point there was discussion of using the design of the X-23/SV-5D as the basis for an unmanned hypersonic reconnaissance vehicle but the project never went forward. The third X-23/SV-5D is now on display at the National Museum of the United States Air Force in Dayton, Ohio. The data gleaned from the X-23 PRIME project proved immensely useful to NASA and Rockwell's engineers during the design of the Space Shuttle and the USAF used the data in its work on the reentry vehicles for its ICBM force.
Source: The X-Planes- X-1 to X-45 by Jay Miller. Midland Publishing, 2001, p256-259.
Thursday, May 20, 2010
During Operation Linebacker over Vietnam in 1972, the two McDonnell Douglas F-4 Phantom II squadrons aboard the USS Coral Sea, VF-111 "Sundowners" and VF-51 "Screaming Eagles" each had their own obstacles to overcome to become some of the premier Phantom units in Southeast Asia. VF-51, in particular, had a double uphill climb as the squadron had just transitioned from the Vought F-8H Crusader AND their new Phantoms weren't so new- they were old F-4B models that had been rejected by the Marines as unairworthy and had been left in storage at MCAS El Toro in California for years.
Many of the senior cadre of pilots at VF-51 were ex-Crusader jocks who lamented the loss of their 20mm cannon and what they perceived the hassle of having a RIO (radar intercept officer) in the back seat. "I'd rather have 500 lbs of fuel than babysit an NFO (naval flight officer, the category of flight crew that were assigned as Phantom RIOs)." The pilots resented their transition training to the Phantom with VF-121 at NAS Miramar where they had veteran RIO instructors in the back seat. "About as fun as having your mother with you on a date" complained one pilot. VF-51's commander, Tom Tucker, ordered his pilots to "dummy up" and play nice with the RIOs to make the transition as smooth as possible.
Soon the ex-Crusader jocks fell in love with their new mounts. Having more power and a better radar than the Crusader was well-appreciated and a few of the former single-seat pilots also started to like having the extra set of eyeballs afforded by the RIOs. Before long, the pilots started to have preferences for certain RIOs but the RIOs themselves were an independent minded bunch. There's an anecdotal story of one RIO teaching his pilot a lesson on crew coordination when during a training mission the RIO shut down all the key radar and avionic systems and told his pilot "Okay, badass, see how well you can fly and fight now." Since the RIO had the switches for those systems, the pilot was left with little to do but keep from crashing. So an unspoken rule developed at VF-51 that RIOs also had say in which pilots they flew with. Many of the Phantom crews ended up flying with the same pilots and RIOs through much of the Coral Sea's 1972 combat cruise.
Having to get the elderly F-4Bs up and running proved to be VF-51's other difficulty in the run up to the 1972 combat cruise. The latest production model was the F-4J which rectified many of the problems with the F-4B, but as the rapid build-up of forces under President Nixon accelerated, any and all Phantoms that could be spared were snapped up by deploying squadrons. In VF-51's case, that meant a motley assortment of hangar queens from MCAS El Toro that hadn't flown since 1968. VF-51 was given free reign to press into service any maintenance crew from any squadron at NAS Miramar to form "Tiger Teams" that worked day and night to get the F-4Bs ready for combat.
With the pilots transitioned and finally working well with their RIOs and the F-4Bs ready to head to war, the only thing left was the come up with new squadron markings for VF-51's mounts. One of the squadron ensigns was sent to a corrosion control and painting course at NAS North Island and he had figured out which panels were opened up the most during routine combat operations. Squadron markings were devised that avoided these panels so they scheme stayed intact and it was one of the most flamboyant Phantom markings to go to sea- what rival squadrons called the "Supersonic Can Opener" was a bright eagle marking with tail feathers that splayed out on the rear fuselage. Even the main landing gear doors were painted with full color eagle talons.
Some of the Miramar command staff told VF-51 that the only thing their Phantoms were missing now were mudflaps and a raccoon tail attached to an aerial! One of the future MiG-killers of VF-51, CDR Jerry "Devil" Houston, recounted in an interview that while other squadrons were looking at ways to tone down their markings and even conceal their aircraft, for morale they wanted VF-51's markings "to be audacious; we wanted to be a magnet for MiGs...intruders in our airspace didn't have to speculate about who just whipped their ass."
Sister squadron VF-111 on the Coral Sea in response adopted an equally flamboyant sunburst tail marking for their 1972 combat cruise as well.
Source: Gray Ghosts: US Navy and Marine Corps F-4 Phantoms by Peter E. Davies. Schiffer Publishing, 2000, p151-153.
Wednesday, May 19, 2010
In 1968 the US Naval Test Pilots School (NTPS) at NAS Patuxent River, Maryland, was struggling how to teach its test pilot students the phenomenon of inertia roll coupling, where the inertia of the heavier fuselage can potentially overcome the stabilizing effects of the wing and tail, particularly in high speed flight. Intertia roll coupling became more of an issue in the fighter aircraft of the day which often boasted long slender fuselages and relatively short span wings. The standard naval jet trainer of the day, the North American Rockwell T-2 Buckeye, despite its benign handling characteristics as a trainer, would react too quickly and at times dangerously to be an effective teaching tool on the phenomenon. The Navy needed an aircraft that had a unusually slow roll rate with a slow speed and good recovery characteristics to that the students of the NTPS could see and experience the evolution and recovery from inertia roll coupling.
The longer the wing span, the slower the roll rate. This made a long-span wing necessary and having a slow speed and good recovery characteristics made a glider aircraft the ideal platform. In an unprecedented move to quickly acquire the right aircraft for the NTPS, the Navy purchased two stock Schweizer SGS 2-32 two-seat sailplanes that could be towed aloft by another unusual aircraft in the NTPS inventory, De Havilland Canada DHC-2 Beavers which were in use to acquaint the NTPS students with tailwheel aircraft and STOL flight.
In order to circumvent the usual lengthy and bureaucratic procedures that come with aircraft acquisition, the Navy had the X-plane designation X-26A assigned to the gliders. They later would be christened "Frigate" after the frigate sea bird. The two X-26A Frigates entered service with the NTPS in August 1968. As the Navy's pilots were inexperienced in glider operations, the NTPS instructors were trained at Schweizer's factory in Elmira, New York. The first two X-26A Frigates were lost in fatal accidents in 1971 and 1972. A third X-26A was procured and unfortunately it, too, was lost in a fatal accident in 1980. Two more X-26A Frigates were purchased to replace the losses that year and to this day they still fly with the NTPS. With two classes going through the rigorous NTPS course each year with an average class size of 30-36, the two Frigate gliders are kept busy.
At one point there was an X-26B. Lockheed and DARPA had a concurrent program that wasn't part of the X-plane program to develop a quiet sensor platform for the Vietnam War. Two Schweizer SGS 2-32 gliders were used in the Project Prize Crew and when they became redundant to the the program, they were passed on to the NTPS as a powered gliders and designated X-26B. One was kept as a spares source for the other which flew, but the X-26B had to be withdrawn from the NTPS due to maintenance problems with its unique modifications for the Project Prize Crew.
This year marks the 42nd consecutive year of X-26A flight operations at NAS Patuxent River, making the Frigate glider the longest-running X-plane program in history, beating out the second longest program, the Bell X-14 VTOL testbed, by a substantial margin.
Source: The X-Planes- X-1 to X-45 by Jay Miller. Midland Publishing, 2001, p282-283.
Monday, May 17, 2010
In 1947 researchers at Wright-Patterson AFB in Dayton began investigations into the possibility of using missiles for bomber defense as the speed of jets and the weight of gun turrets made existing systems for bomber defense impractical. General Electric was the first to receive a USAF contract to pursue such studies, but soon transferred the work to Hughes where the missile developed didn't end up on bombers but on interceptors as the Falcon missile. McDonnell was next in 1952 to try and develop a jet-vane controlled defensive missile for the Convair B-58 Hustler, but the work was canceled in 1956. By that time, however, work began on the WS-110A project that would result in the North American XB-70 Valkyrie and more contracts were issued to study what the Air Force was calling DAMS- Defense Anti-Missile Subsystem, a system that fired a stream of pellets at inbound missiles. Again, those studies ended in 1959 despite some encouraging tests.
The USAF wasn't deterred, though, starting a program in 1958 in cooperation with North American and Convair called Pye Wacket for a defensive missile for the XB-70 Valkyrie. Three basic shapes were first evaluated by North American and Convair- a standard but modified version of the AIM-47 designed for the F-108 Rapier, a cylindrical missile using jet vane directional control, and an unusual saucer-shaped missile called a "lenticular defense missile". Studies showed the lenticular design the most promising as its shape allowed it to be pointed in any direction and fired, not wasting kinetic energy on turning towards the incoming threat.
By 1959 the USAF did a considerable amount of wind tunnel work at the Arnold Engineering Development Center in Tennessee of the lenticular Pye Wacket design. It was stable all the way to Mach 6. It had a diameter of 70 inches, was 9 inches deep at its thickest portion and weighed only 510 lbs. One end of the saucer shape housed the infrared seeker and two rocket motors were on the opposite end to give the Pye Wacket a range of approximately 72 nautical miles. A set of spoilers built into the curved surfaces of the missile provide directional control.
North American began to seriously consider the Pye Wacket missile for the XB-70 Valkyrie- posts were mounted vertically in the forward section of the weapons bay and the missiles were mounted on the posts via a screw thread that ran through the center of the missile. This way the saucer-shaped missiles could be threaded on the post and stacked. Two stacks of five missiles each would fit in the Valkyrie's weapons bay. When needed, the post rotated to point the lowest missile in the stack in the direction of the inbound target. The missile was then dropped out of the bay already pointed at the target at which point the rocket motors fired.
In the summer of 1959 Convair was awarded a design contract to further study the lenticular Pye Wacket design and modified the saucer shape to incorporate a blunt trailing end where the rocket exhaust was located. This improved the supersonic drag as well as the controllability of the missile. Roll reaction thrusters were added along with small lateral vanes as well as the original spoilers used on the original design. With over 80 hours of wind tunnel testing from speeds as low as Mach 0.6 to Mach 5, sled tests then took place at Edwards AFB on a full-scale article powered by three Thiokol solid rocket motors, the same type used singly on the AIM-4 Falcon air-to-air missile.
The tests reported accelerations on the order of 60G with the ability to make sharp high-G turns at supersonic speed without loss of control. An operational version of the Pye Wacket arming the Valkyrie would be 48 inches in diameter, carry a 50 lb warhead and be capable of extreme maneuvers up to Mach 6. Convair recommended that the Air Force procure 12 missiles for continued testing, but no documentation has been found that further details work done from that point on on the lenticular defense missile.
Convair also had proposed a strike version of the Pye Wacket that would allow a bomber to easily strike targets on each side of its flight path without having to overfly enemy defenses. A version was also suggested by the company to use as a highly maneuverable re-entry warhead for ballistic missiles.
It's always been a point of curiosity to me as an aviation geek why a weapon as promising as the Pye Wacket never got developed further. Or did it? Conspiracy theorists might think the Pye Wacket was classified and modern versions of the lenticular defense missile moving at speeds unattainable by manned aircraft might account for a good portion of the UFO sightings pointing to a super-maneuverable vehicle. Considering that the basic layout was stable at hypersonic speeds, it certainly would make a very capable rapid-strike weapon.
Now if you'll excuse me, I have to go fetch my tinfoil hat.
Source: Valkyrie: North American's Mach 3 Superbomber by Dennis Jenkins and Tony Landis. Specialty Press, 2005, p220-226.
Sunday, May 16, 2010
During the Second World War Boeing worked extensively on further improvements to the B-29 Superfortress. The most important of these improved variants was the B-29D that involved swapping out the Wright R-3350 radial engines with the more powerful Pratt & Whitney R-4360 Wasp Major radial engine. In July 1945 the USAAF signed a contract for 200 B-29Ds, but with the end of the war and the rapid postwar demobilization, the B-29D contract was canceled. With the creation of an independent United States Air Force in 1947, there was a need for interim bombers pending the arrival of more advanced jet bombers. The USAF was already getting the Convair B-36 which took on the mantle of the heavy bomber, but the USAF also wanted the B-29D which would be redesignated as a medium bomber. The USAF had the B-29D redesignated as the B-50 to avoid the appearance of ordering a "wartime" bomber. Making its maiden flight on 25 June 1947, the B-50 Superfortress would eventually result in 320 examples of all variants produced.
Boeing, however, was working on an even more powerful and longer-ranged development of the B-50. Designated the B-50C, this evolution into the ultimate Superfortress was designed to extract as much speed and performance as was possible using a new version of the Pratt & Whitney R-4360 Wasp Major engine that added what was called a "variable discharge turbine" (VDT) to the engine. The standard Wasp Major used on the B-50 developed approximately 3,500 horsepower and a Wasp Major with a VDT could easily produce 4,000 horsepower, making it one of the most powerful production piston engines in the world.
The VDT consisted of two General Electric CHM-2 turbosuperchargers that collected the hot exhaust gases from the 28 cylinders of the Wasp Major. A portion of the hot gases were diverted through an intercooler to provide turbosupercharging at high altitudes. The bulk of the hot gases went through the CHM-2 turbines and were exhausted out a variable area nozzle that resembled a set of eyelids. By adjusting the size of the nozzle, jet thrust could be achieved that had the potential to add as much as 15% to the speed of the B-50C over the production standard B-50.
The scope of the changes needed to for the B/RB-54 resulted in a redesignation to B-54 with the planned reconnaissance variant being the RB-54. The jump in power output from the use of the Wasp Major VDT resulted in a redesign of the wings that resulted in a wingspan that was over 20 feet longer than that of the B-50. This provided additional fuel capacity along with external fuel tanks on the outboard wings. The wingspan increase was so much that outrigger gears were needed under the outermost engine nacelles. Wind tunnel testing had shown that the new wing and powerful engine output also required a longer fuselage and the B/RB-54's fuselage was stretched 10 feet .
By comparison, the B-29 weighed 120,000 lbs fully loaded and the B/RB-54 would weighed in at 207,000 lbs at takeoff. The Wright R-3350 engines of the B-29 developed 2,200 horsepower and the bomber had a range of approximately 3,250 miles. The B/RB-54 would have been able to push 8,000 miles of range. The mockups were completed in 1948 and the contract was signed for 43 bombers as an initial production lot.
While the Secretary of the Air Force Stuart Symington and the USAF Chief of Staff General Hoyt Vandenberg were supportive of the B/RB-54 project, General Curtis LeMay, the head of the Strategic Air Command, felt that the B/RB-54 was inferior to the Convair B-36 Peacemaker particularly the B-36D that added four J47 jet engines under the outer wings. Pending the arrival of the B-52 Stratofortress, LeMay felt deterrence was better served by the B-36 which could fly faster, farther, higher, and carry a significantly larger bomb load. In the postwar atmosphere of austerity, more B-36s couldn't be accommodated in the Air Force budget and Secretary Symington offered LeMay more B-50s instead of increased numbers of B-36s. This was even more unsatisfactory to the outspoken SAC commander who then argued that if he couldn't get more B-36s, then the funding set aside for the B/RB-54 should be shifted over to get more of the Boeing B-47 Stratojet which made its first flight in December 1947. This was agreeable to all involved and the B/RB-54 project was cancelled with the prototype approximately 75% complete at Boeing's Seattle facilities.
The B-29 lineage would live on, though, in the C/KC-97 Stratofreighter (the last examples being retired in 1978) and in the commercial Boeing 377 Stratocruiser. But neither would have matched the leap in peformance of the B/RB-54, the "ultimate" Superfortress.
Source: Boeing B-29 Superfortress (Crowood Aviation Series) by Steve Pace. The Crowood Press Ltd, 2003, p166-168.
Saturday, May 15, 2010
In the early morning hours of 29 August 2005, Hurricane Katrina made landfall near New Orleans as a Category 4 storm. In addition to the widespread flooding and destruction, the storm also destroyed much of the area's communications infrastructure from cellular towers to air traffic control systems. As an integral part of Joint Task Force-Katrina (JTF-Katrina), the US military, civilian agencies, and those nations who came to assist needed airspace coordination with as many as 80 helicopters alone airborne throughout the area rescuing survivors and inbound relief flights and outbound evacuation flights.
Two Navy E-2 Hawkeye squadrons provided air traffic control and coordination as well as a detachment of P-3 AWACS aircraft from the US Customs Service. The two Hawkeye squadrons involved were the reserve unit VAW-77 "Nightwolves" (call sign WOLF) from NAS Atlanta and VAW-126 "Seahawks" (call signs SEAHAWK and CLOSEOUT) from Carrier Air Wing Three embarked on the USS Harry S Truman which was sailing in the Gulf of Mexico assisting with relief efforts. In addition, the US Customs P-3 AWACS (which use a similar radar system as the E-2) from their home base in Corpus Christi (call sign OMAHA) also assisted the Navy Hawkeyes.
The E-2's radar and extensive communications suite allowed the crews to monitor the airspace, assist in location of stranded survivors, direct rescues, air traffic control and even identify with the radar safe landing areas and locations of tall obstructions. The two squadrons adopted the same system used for directing close air support for the New Orleans environment, using a grid and keypad system overlaying the area to coordinate and direct rescue aircraft and deconflict the airspace much in the same way fighters and strike aircraft might be directed to targets. At times a single E-2 might be controlling as many as 80-90 helicopters operating over the metropolitan area.
The E-2 Hawkeye has a crew of five- two pilots up front and three NFOs (naval flight officers) in the back who provide the airborne control and communication. The center seat is usually occupied by the commander or combat information officer who directs the efforts of the two NFOs on each side. Many of the helicopter pilots involved in the relief preferred working with the E-2 Hawkeyes as the smaller number of crew aboard made decision-making quick compared to the larger platforms like the P-3 AWACs. All one of the NFOs would have to do to direct a rescue effort was to turn to his commander and ask for clearance.
Source: Flying the World's Greatest Aircraft: Superlative Military Machines from Sabre to Raptor, James Bennett, editor. Fall River Press, 2009, p81.
Thursday, May 13, 2010
While liquid-fueled rocket engines have been the mainstay for the satellite launch industry, the long road of technological development in solid-fuel rockets have also benefited the aerospace industry. Often times unique solutions were needed in the development of solid-fuel rockets. One of the more unusual ones was the use of liquid freon to direct the exhaust flame from solid-fueled rockets. That's right. Liquid. Freon. How? I'll get to that.
In the 1950s the conventional wisdom in ICBM development was that only liquid-fueled engines had the power to lift the heavy nuclear warheads of the day. The two main ICBMs in development, the Atlas and the Titan, used liquid-fueled engines. But the US Navy, seeking to put ICBMs on nuclear submarines as a sea-based strategic deterrent, considered liquid-fuels on a submarine wholly impractical and not just for safety reasons. As a result, the engineers who were developing the Polaris SLBM focused their efforts on solid-fuel rocket motors for the missile. They were storable and could be quickly fired. In addition, with enough right mix of solid propellants, the missile could be much smaller than a comparable liquid-fueled missile.
The advantages of a storable propellant and rapidity of launch made solid-fuel an attractive option for a land-based ICBM as well. In the US Air Force, General Bernard Schriever was in charge of the Air Force's ICBM development effort as the head of the Western Development Division. While he initially believed that liquid-fueled engines were the only way to power an operational ICBM, he was ably convinced by several of his engineers to look at solid-fuels as an alternative. That tangent then took on an important priority equal to that of the Atlas and Titan programs, becoming the Minuteman ICBM which was developed in the same time frame as the Navy's Polaris missile and the two weapons shared many similar characteristics due to their solid-fuel rocket engines.
The first solid rockets used tabs that jutted into the exhaust stream to deflect the plume for directional control. It was the simplest system but to provide effective control and deflection, the tabs had to be of a size that inevitably cut into the exhaust stream's total velocity. The next solution was what the Polaris team called "jetevators". The exhaust cone of the solid rocket had an extension at the bottom of the cone that was in effect, a gimbaled extension of the skirt and small actuators moved the whole extension. Jetevators were used on the first versions of the Polaris SLBM. The main disadvantage of jetevators was they added technical complexity to the solid rocket motor as well as weight. Small jetevators could only provide slight corrections but to provide more significant directional control, larger and heavier jetevators would be needed.
Both the early versions of Polaris and Minuteman used jetevators on each of the three stages of the missiles, with the first and second stages of both missiles having four nozzles that could be differentially vectored to provide control. By 1962, however, the next versions of the missiles were already in development- for Polaris it was the A3 version (third version) and for the Minuteman it was the Minuteman II (second version, obviously). In both missiles a range increase was desired and one way to get it was to lighten the missile itself. For both new versions, the second stage switched from four nozzles with jetevators to a single nozzle that used what was called "liquid injection thrust vectoring control".
Around the perimeter of the nozzle about 1/2 the way up were a series of four ports that angled slightly upward. Liquid freon was injected into one of the ports and as it did, it created a shockwave in the nozzle that pushed the exhaust stream in a direction up to 7 to 10 degress opposite from the port the freon entered. The freon didn't react with the hot plume, it merely created a thermal shockwave that pushed the plume one direction. By injecting freon into the various ports, directional control could be achieved for a lot less weight.
On the Minuteman II, the second stage carried 262 pounds of freon in a rubber bladder to use for thrust vectoring. The Minuteman II and Polaris A3 weren't the first missiles to use this novel method of control. That honor goes to the Lance short-range battlefield missile that was used by the US Army until the 1960s. The knowledge gained from the Minuteman II and Polaris A3 in liquid injection thrust vectoring control would be used to its fullest on the large solid rocket boosters used on the Titan III and Titan IV launchers, long the mainstay of US expendable heavy-lift vehicles. Both boosters on the Titan launchers used liquid injection thrust vectoring control. If you look at a picture of a Titan III/IV at launch, you'll notice a small external tank attached to the core rocket's base, one for each booster. That's the reservoir for the liquids used for the thrust vectoring system of the solid rocket boosters.
The Polaris has since been superseded in the Navy's strategic deterrent by the Poseidon and then the current missile, the Trident. The Minuteman II was retired from service and the land-based ICBM deterrent for the United States relies on the Minuteman III.
Source: To Reach the High Frontier- A History of US Launch Vehicles, edited by Roger D. Launius and Dennis Jenkins. The University Press of Kentucky, 2002, p262-266.
Wednesday, May 12, 2010
By any measure of the day, the Boeing B-29 Superfortress was a quantum leap in aviation technology which unfortunately came with a lion's share of problems to be resolved before it was committed to combat operations. Keep in mind that when the B-29 was ordered into production, Pearl Harbor hadn't even happened yet and the first flight of the XB-29 prototype was still over a year away. On 6 September 1941 the US Army Air Corps (soon to be the US Army Air Forces) placed its initial production contract for 250 B-29s- and not only were these B-29s to be built not in Seattle but in Wichita, but the USAAC wisely ordered some of the B-29s to be license built from other manufacturers- Bell (at their Atlanta plant) and Martin (at their Omaha plant). Without the United States yet involved in war, the initial B-29 contract caused a firestorm with Congress that went away quickly as the first bombs fell on Pearl Harbor.
As Boeing lacked production space at its Renton, Washington, plant, the USAAC wanted production at Boeing Wichita which at the time was building biplane trainers and B-17 control surfaces. This caused a furor in Seattle, but the USAAC insisted on the security of a plant deep inland given that the B-29 would be a game changer once it entered service. Only the first three B-29s were built in Seattle.
The need for expansion at Boeing Wichita resulted in one of the largest population booms of the once quiet Kansas town. But as the flight test program of the B-29 progressed and the war widened in scope, more B-29s got added to the production order. By January 1944 Boeing Wichita alone had orders for 1,630 Superfortresses. But in that month, the production line was in chaos. Fewer than 100 production-standard B-29s had been completed and worse yet, an assessment by the 20th Air Force found not a single B-29 was ready for combat for a variety of technical reasons. Of those 100 Superfortesses completed and still in Wichita, less than 16 were flyable due to a lack of various components.
The legendary commander of the US Army Air Forces, General Henry "Hap" Arnold was surprisingly unaware of the situation when he arrived at Smoky Hill AAF in Salina, Kansas that January expecting to see off the first B-29 unit to be deployed to the Pacific, the 58th Bomb Wing. To say that General Arnold went ballistic would be understatement! All the available flying B-29s were being used for crew training and as such, many of them weren't even fitted with the defensive gun system let alone any of the other systems necessary for combat. Even worse, there was a shortage of qualified B-29 mechanics to get any aircraft combat ready.
If there was one man who had every right to be upset, it was General Arnold. Long passionate about the need for strategic bombing in any future war, in the face of criticism and doubt he championed the need for the B-29. He immediately placed his deputy, General B.E. Meyer in charge of a crash, round-the-clock program to get the B-29s combat ready. It started in early March 1944 and is known as the "Battle of Kansas", probably one of the most important battles the B-29 has ever had to fight. And it didn't help matters any that back in January General Arnold himself selected the still-under construction 175th Superfortress to be his aircraft and he wanted it ready by March 1st. That aircraft was named "The General H.H. Arnold Special" and it was th last of the first 175 B-29s involved in the Battle of Kansas.
Boeing brought in additional personnel to assist the USAAF mechanics in getting the B-29s combat ready. As these aircraft were already parked outdoors, much of the work had to be done in the bitter Kansas winter with personnel wearing warm high altitude flight suits and gloves which further slowed the work. Assembly line workers were diverted to assist as well as three eight-hour shifts were set up on the Boeing Wichita ramps to get those B-29s ready. Heated tents were set up near the flightlines so workers could take heated breaks from the cold weather. Twenty-four hours a day, seven days a week, for 35 straight days that first group of B-29s were readied for combat in some of the most atrocious winters in Kansas history. By the end of the month, the Battle of Kansas was won. With the coming of spring and the warmer weather, the first groups of combat-ready Superfortresses departed Wichita for the main B-29 training base, Smoky Hill AAF about 120 miles to the north of Wichita. The last of those 175 B-29s left for Salina on 15 April 1944.
In fact, the first of the 58th Bomb Wing's combat-ready B-29s were already heading out to the Pacific on 10 March 1944, their aircraft being some of the first to have been through the Battle of Kansas.
Source: Boeing B-29 Superfortress (Crowood Aviation Series) by Steve Pace. The Crowood Press Ltd, 2003, p39-40.
Tuesday, May 11, 2010
During the Second World War one of the most powerful inline piston engines was the British Napier Sabre, 24-cylinder piston engine in an H-block layout (imagine 2 flat 12-cylinder engines on top of each other) that in its first versions developed 2,200 horsepower and its late-war versions developed as much as 5,000 horsepower. The Sabre powered the Hawker Typhoon and Tempest fighter bombers but the first aircraft to use Napier's innovative engine flew for only a short time before the start of the Second World War. During the interwar period there was considerable national rivalry in setting aviation world records, one of which was unlimited speed record.
In 1934 the record was held by the Italians at 440.6 mph set with the Macchi-Castoldi MC.72 floatplane powered by a 24-cylinder Fiat engine. The British were aware that the Germans would making an attempt at the world speed record using the Daimler-Benz DB601-V12 engine that was under development and more advanced than any other engine of the day (the DB601 would go on and power the Messerschmitt Bf 109 fighter). The Napier Sabre team decided to build its own record-breaking aircraft powered by the Sabre engine. They had one of two p0ssible goals- to either wait for the Luftwaffe to set the record and then use their aircraft to break it right away or to fly and set a record that was so fast it couldn't be broken for years.
Rather unusually with with method, Napier selected the small light aircraft company Heston to build what would be called the Napier-Heston T.5 (for Type 5, the fifth type of Heston aircraft they had built). Heston was selected because they had an established reputation for fine woodwork in their aircraft- with wood being light, strong, and not needing rivets- some have called wood "God's composite material"- the wooden Heston design would be strong yet very light.
The aircraft was then finished with 20 coats of lacquer paint to a smooth finish and any scratch more than 0.0005 inches in depth was polished out in areas like the wing leading edges. George Cornwall, the chief designer from Heston, and Arthur Hagg, the lead Napier engineer on the project, created an aircraft of unparalleled smoothness and aerodynamic fineness. One of the key features of the T.5 was it's midfuselage belly radiator, the first aircraft to have one that would be echoed in the later North American P-51 Mustang. The belly scoop was designed to bleed off the turbulent boundary layer air to ensure a smooth airflow into the air scoop. After passing through the twin oil and glycol radiators, the air was exhausted on each side of the rudder via D-shaped exhaust ports. The cockpit canopy was a small, one piece blown perspex bubble similar to what is on today's Reno Unlimited Class racers.
The T.5 weighed in at 7,200 lbs, 2,900 lbs of which was the Napier Sabre engine- a staggering 40% of the aircraft's weight. By comparison, the P-51 Mustang weighed in at 9,200 lbs empty with its Merlin engine accounting for 1,645 lbs of that weight- only 18% of the total. For its flights, the Napier Sabre was tuned to produce 2,650 horsepower. As the British government was preoccupied with numerous military projects, the Napier-Heston T.5 would use private backing to make its record flight.
With delays in the ground runs and taxi tests, the T.5 finally took to the air on 12 June 1940. It had been just over a year since the Germans took the world record with the Messerschmitt Me 209 and its DB601 engine with a speed of 469.22 mph. The British were gunning for 480 mph with the T.5. With Heston's chief test pilot G. Richmond in the cockpit sans canopy, the first flight was planned to be a basic exploration of the aircraft's handling qualities. Five minutes into the flight, the engine was overheating and Richmond found the aircraft to be overly sensitive in pitch. Lacking the canopy, he was buffeted by the 200-mph slipstream. Then a broken radiator fitting scaled him with steam from the radiator. He hastily made for landing without a good idea of the aircraft's ideal landing speeds only to discover what the stall speed was when he was still 30 feet above the ground.
The T.5 pancaked into the ground, driving the landing gears through the wing. The tail broke off and Richmond survived with significant burns. No further attempts were made as one month later the Battle of Britain began. The T.5 had a total of six minutes of flying time.
Source: Aviation History, July 2010. "Built for Speed" by Stephan Wilkinson, p18-19.
Monday, May 10, 2010
No launch vehicle is so closely identified with the satellite communications industry than the Delta rocket. A direct descendant of the 1950s Thor intermediate-range ballistic missile and initially known as the Thor-Delta, through the 1960s the Delta rocket had firmly established its reputation as a reliable medium-lift launch vehicle that had not only orbited the first telecommunications satellites (Echo, Syncom, Telstar) but also the first weather satellites (TIROS) as well as a wide range of scientific probes (the Explorer series and the OSO solar-observation satellites). The vehicle was progressively modified for increases in capacity and performance but the real revolution launched aboard the Delta rocket would come in 1972.
The early Delta rockets used the Rocketdyne MB-3 liquid fuel engine for the first stage, the MB-3 being derived from the MA-3 engine that Rocketdyne built for the Atlas ICBM. Rocketdyne began work on a successor engine called the H-1 that would be used on the Saturn IB rocket for NASA. Having progressively tweaked the design to a nearly 50% increase in thrust, Rocketdyne built 322 H-1 engines for NASA and it was a relatively easy task to adopt the proven H-1 to be the new Delta first stage engine as the RS-27.
At the same time the Delta got a new, more powerful engine, in June 1972 the Federal Communications Commission decided to allow private companies to compete for domestic satellite communications. Prior to this, only international communications had any competition. RCA Global Communications was the first out of the gate by leasing transponder space on Canada's Anik 1 satellite. Anik followed the trend of communications satellites of they day- it was drum shaped and spin-stabilized, with solar cells on the drum and the antennas atop the drum on a de-spun mount that pointed to Earth from geostationary orbit. On 13 April 1974, Western Union's Westar 1 was launched aboard the Delta to become the first American domestic communications satellite after the 1972 FCC decision. Westar 2 soon followed into orbit.
But for RCA, this wasn't enough just to use rented transponders on other companies' satellites. RCA developed its own line of satellites, the RCA Satcom series, but unlike the spin-stabilized designs of the day, RCA Satcom 1 was three-axis stabilized with long solar panel "wings" that could be pointed to the sun for optimum efficiency which meant more power for the communications transponders and more importantly, the ability to power more transponders than was possible on a spin-stabilized satellite.
Unfortunately, Satcom 1 and its family were too heavy for the existing Delta rockets but were too light for the next vehicle up, the Atlas-Centaur. In negotiations with NASA and the Delta's builder, McDonnell Douglas, RCA signed a unique contract with McDonnell Douglas paying for a portion of the development of a new, more capable Delta rocket that used the RS-27 engine and added three Castor IV solid rocket boosters built by Thiokol to increase the lift capacity of the rocket. It was the first time in history that a private company funded launch vehicle development.
On 13 December 1975 a Delta 3914 rocket launched RCA Satcom 1 into geostationary orbit, making it the first three-axis stabilized communications satellite in space and the first satellite launched on a rocket that was partly funded by a private company, RCA.
The success of the new Delta versions was immediate and the rocket would dominate the telecommunications satellite market until the arrival of the European Ariane launcher in the 1980s.
There's an interesting historical sidenote to RCA Satcom 1- Sid Topol, the president of a communications company called Scientific Atlanta, brought together a small Pennsylvania-based cable TV provider that had only 8,000 subscribers. The cable company also showed unedited commercial free movies and pay-per-view boxing matches and was having trouble expanding, having to rely on a costly network of microwave relay towers. On the heels of the 1972 FCC decision, Topol proposed that his company would build ground stations that would allow the cable TV provider to use RCA Satcom 1 to broadcast its content to other cable providers around the nation. A cable TV provider in Vero Beach, Florida, agreed to be a test market with its network of 10,000 subscribers for this innovative service that was an instant success.
The name of that small, struggling, Pennsylvania cable TV provider? Home Box Office. That's right, HBO. You all know the rest of the story from there!
Source: To Reach the High Frontier- A History of US Launch Vehicles, edited by Roger D. Launius and Dennis Jenkins. The University Press of Kentucky, 2002, p128-130. Additional information from http://kevinforsyth.net/delta/backgrnd.htm.
Saturday, May 8, 2010
In the 1930s Germany, the Horten brothers, Reimar, Walter, and Wolfram, had made a name for themselves creating elegant flying wing gliders of an advanced design. They joined the Luftwaffe in 1936 as pilots, but Reimar and Walter were encouraged to continue their advanced design work while Wolfram went on become a Heinkel He 111 pilot. He was killed in battle having been shot down over Dunkirk in 1940 but had participated in the early development of the Horten glider designs. With the outbreak of the Second World War in 1939, they were offered jobs with Heinkel and Messerschmitt, but disagreements with Ernst Heinkel and Willy Messerschmitt scuttled any employment with the prestigious firms. With knowledge of Northrop's advanced flying wing work in the United States and a war going on, senior Luftwaffe officials established Sonderkommando 9 at Gottingen Airfield with the brothers in command to allow them continue development work on their flying wing designs.
In 1944 the German Air Ministry (Reichsluftfarhrtministerium, RLM) issued a requirement for a long-range bomber that was capable of bombing the East Coast of the United States. The RLM called for an aircraft that could fly at high altitude for a round trip of 7000 miles and carrying either four tons of bombs or one "special weapon". Five designs were submitted, but every company that participated had aired concerns that the requirements were beyond existing technology. As a result, the RLM scrapped the competition.
Though they didn't submit a design for the long-range bomber, the Horten brothers were aware that none of the designs could meet the demanding specifications. On their own they decided to work on a flying wing design that they thought might be better able to make the trans-Atlantic bombing mission. Designated the Ho XVIII Amerika Bomber, the Hortens had created 10 different design variations by January 1945. Their preferred design was a pure flying wing design with six buried engines that would have been either the advanced Heinkel He S 011 turbojet or the Junkers Jumo 004B design, the Heinkel engine obviously being preferred. The intakes were located on the inner wing leading edges. Various weight saving measures were considered from using rocket-assisted takeoffs from a trolley to mid-air refueling.
On 25 February 1945 the brothers were invited to Berlin to present their Amerika Bomber design to the RLM. Also present were representatives from the five companies that had participated in the original competition. Several days later the RLM informed the Hortens that their design would meet the original specification but that Junkers would build the bomber with assistance from Messerschmitt. At a later acrimonious meeting with the engineers from the two firms, the Ho XVIII bomber ended up with a major redesign, ending up with a large central fin, fully retractable undercarriage and the use of the Jumo 004B turbojets in two nacelles under the wings. As a result, Reimar Horten created a compromise design designated the Ho XVIIIb that used the preferred Heinkel engines. With the war going poorly for the Nazi regime, the RLM wanted the bomber in service as soon as possible. Two large underground hangars were constructed to use as production facilities along with construction of a suitable runway in the German state of Thuringa.
The RLM anticipated production in the fall of 1945, but the war in Europe ended with the German surrender in May 1945. It's not known if any work had started on the Ho XVIII, but given the poor reliability of the early jet engines- the Jumo 004B were worn out after only 25 flight hours- it seems a tall order for a jet bomber to be able to reach targets on the US East Coast from Germany and even it was possible, the sheer amount of war material that was being poured into the European war effort would have made any such attacks unlikely to have changed the course of the war. In 1944 alone, the amount of fuel consumed by a single Allied one-thousand bomber mission over the Reich was more than the entire German petroleum refining output for an entire month!
Source: Secret Projects- Flying Wings and Tailless Aircraft by Bill Rose. Midland/Ian Allan Publishing, 2010, p51-52.
Thursday, May 6, 2010
One of the more interesting research programs in the US space effort involved the work on nuclear rockets. Such exotic methods of propulsion are attractive in that a rocket powered by nuclear fission in more efficient than a chemical rocket and generates much more thrust than conventional rockets, making trips to the Moon and the outer planets much shorter than using gravity-assist methods. The first examination of rockets using a nuclear fuel was touched upon by the early pioneers such as Konstantin Tsiokolvsky and Robert Goddard, but the means of containing the explosive power into a controlled release challenged early engineers theorizing on the prospect.
It wasn't until the first controlled fission reaction took place in 1942 at the University of Chicago under the direction of Enrico Fermi that more serious consideration was given to nuclear rocket propulsion. The first serious study of a nuclear rocket took place in 1947 in a classified engineering analysis done by North American Aviation and outlined some of the key technical hurdles. At the same time, United States Atomic Energy Commission (AEC) had done considerable work on the use of nuclear power on aircraft in which air would be superheated by a nuclear reactor and expelled as exhaust in a nuclear jet engine. The work was to have culminated in the Convair X-6, a variant of the B-36 Peacemaker, but the work was eventually canceled. All was not lost as the AEC's effort in designing a nuclear jet engine had direct applications to nuclear rockets which instead of air, used liquid hydrogen would be run past a nuclear reactor and expelled as a high-velocity superheated exhaust.
Robert Bussard, an engineer at the Oak Ridge National Laboratory in Tennessee that had worked on the nuclear jet engine shifted his focus to nuclear rockets and in 1953 published a report examining the feasibility of nuclear rockets. As nuclear reactors became smaller as part of the US Navy's drive for nuclear submarines, a technological threshold was reached in which a small yet powerful reactor for a rocket was possible.
As a result of Bussard's work the US Air Force and the AEC initiated Project Rover to begin work on a nuclear rocket engine in 1955. At the time the USAF was considering either a nuclear rocket or nuclear ramjet for strategic weapons but during this time period advances in solid-fuel rockets displaced nuclear rockets for the ICBM force. A site at the Nevada Test Site called Jackass Flats was established in 1957 to test the designs, the first of which was designated "Kiwi-A" (as the engine wasn't meant to take flight). Several versions of the Kiwi engine were tested at Jackass Flats to test out various systems for not only containing the nuclear reaction but also to control the engine thrust as well as shut down and restart systems.
Since the USAF's original intent in getting involved in nuclear rockets was to have an engine that could lift the heavy nuclear warheads of the time, the technological advances in miniaturization in warhead design as well as progress in solid fuel rockets made nuclear rocket engines unnecessary and in 1960 President Eisenhower transferred the USAF's part of Project Rover to NASA which then set up the AEC-NASA SNPO, Space Nuclear Propulsion Office, where the nuclear rocket engines were considered for the Apollo lunar program and beyond. When President Kennedy laid out his goal of reaching the Moon in his famous speech, he increased funding to the SNPO threefold and the program began work on a more refined engine called NERVA (Nuclear Engine for Rocket Vehicle Applications) in 1961.
Aerojet-General and Westinghouse were awarded contracts in the NERVA program for nuclear engines based on the Kiwi-B design that had been tested at Jackass Flats under Project Rover. With the successful test firing of the NERVA engines, NASA began plans to incorporate the NERVA engine as the third stage of the Saturn V rocket and in 1962 Lockheed was selected to be the prime contractor for the Saturn nuclear third stage which would be designated Saturn-N in which the NERVA-powered third stage would carry the Apollo crew and their spacecraft and lunar module to the Moon.
Within a year, however, NASA decided that the success of the Apollo program depended upon reliability and the Saturn-N third stage was replaced with a conventional liquid-powered rocket engine. The NERVA program was converted to the status of a technology demonstration for possible future uses for manned missions to Mars. Between 1964 and 1969, thirteen different nuclear rocket engines were tested at Jackass Flats, validating the technology. The first Kiwi-A and -B engines used reactors in the 70 Megawatt range which gradually increased in power as testing proceeded.
In 1965 the Kiwi engines were replaced by the more powerful Phoebus engines that were being considered for the manned missions to Mars. The first Phoebus engine test in Nevada ran at just over 1000 MW and by 1968 the last versions of the Phoebus engine were generating over 4000 MW! For comparison, Hoover Dam generates just over 2000 MW of power. The reactor core of the Phoebus engine was ONLY the size of an office desk! But with the success of the Apollo program assured and the costs of the escalating Vietnam War climbing, budget cuts were made and despite the impressive technological success of Project Rover and the NERVA program, work was halted in 1973 under President Nixon.
NASA still has its proponents of nuclear propulsion and in 1989 when President Bush announced a plan for a manned mission to Mars by 2019, the work on NERVA got dusted off only to have its budget slashed again to complete the International Space Station and sustain the Space Shuttle program.
Source: To Reach the High Frontier- A History of US Launch Vehicles, edited by Roger D. Launius and Dennis Jenkins. The University Press of Kentucky, 2002, p60-63.
Wednesday, May 5, 2010
Following the October 1957 launch of Sputnik 1, the US was badly in need of a morale boost in the nascent space race. The Navy's Vanguard rocket program was given the green light to launch in December 1957 and the first stage failed on the launch pad, giving the Soviets a propaganda coup as the launch was publicized in advance. The Army's Jupiter program led by Werner Von Braun had been given the green light after the failure and on 1 February 1958 a modified Jupiter IRBM designated Juno I put the Explorer 1 satellite into orbit.
By the summer of 1958 the Soviet Union had already orbited Sputnik 2 (carrying the dog Laika and the first satellite to weigh over 1,000 lbs) and Sputnik 3, the first satellite to weigh over a ton. It didn't take much to realize that the Soviet Union had already put over 3,000 lbs worth of satellites in orbit using the massive R-7 ICBM and the United States only had less than 70 lbs in orbit, Explorer 1 and the diminutive Vanguard 1 weighing only 3.5 lbs. The head of the Advanced Research Projects Agency (ARPA, which later became DARPA), Roy Johnson, contacted the Air Force about the possibility of orbiting an entire Atlas ICBM which would put four tons into orbit and constitute a huge morale boost for the struggling US space effort.
The concept of putting an entire Atlas missile into orbit was radical- only eight Atlas missiles had been test-flown up to that point and only three were successful. Those early Atlas missiles were the Atlas A variant which had only two engines while the Atlas B had three engines (two of which were dropped as boosters, leaving the center engine to act as the sustainer) and it had just failed on its maiden flight. But Roy Johnson, having seen the Atlas A test data, knew that the performance estimates were conservative and that the Atlas A test flights indicated that the three-engined Atlas B could do it, particularly if all the heavy test and telemetry instrumentation were removed from the missile. But if it could be down, it would but the entire missile and a 300-lb payload into orbit minus the two booster engines. It would be in his words "A master-stroke in the space war" against the Soviets.
ARPA and the USAF agreed on the plan to secretly prepare an Atlas B for launch into orbit. Along the way it was decided that the payload would be a recording and transmitting package that would broadcast a message of peace from President Eisenhower. It would orbit the Earth every 90 minutes at an altitude of 100 miles. The program became Project SCORE (Signal Communication by Orbital Relay Equipment).
Only 88 engineers at Convair and the USAF worked on Project SCORE. Atlas missile 10B was selected for the mission and Rocketdyne, the maker of the Atlas engines, introduced performance enhancements and tweaks to a select group of engines called "Hotrods". Eisenhower, however, was reluctant to lose any more face in the competition with the Soviets particularly in light of the failure on the maiden flight of the Atlas B (designated 3B). The successful test flight of Atlas 4B failed to sway the President but ARPA and the USAF convinced him that the SCORE payload was a crucial test of communications technology and if the missile failed to reach orbit, they could always say that it was a successful ballistic missile test down the Atlantic Missile Range from Cape Canaveral.
Reducing the weight of the Atlas was essential and many systems planned for the Atlas C were incorporated into the 10B vehicle. As it was necessary to allow the various other personnel and contractors to go about their usual work, the 88 individuals (who called themselves the "88 Club") who knew of Project SCORE had to give excuses to non-cleared staff to allow the project to move forward. The head of the project, Col. Asa Gibbs, and his counterparts at Convair kept a notebook of all the excuses they used in an effort to be consistent while guarding the secrecy of the project.
The SCORE package developed by the Army Signal Corps had two tape recorders with one acting as back up as well as the necessary communications equipment to be activated from ground stations. The recording from President Eisenhower arrived at the Cape on the eve of the flight on 18 December 1958 but the SCORE payload was already buttoned up on the Atlas. So the Army had to transmit the message from a trailer hidden in a swamp near the launch pad, but when they did so, part of the President's message got erased. No problem, they could re-upload the recording once the Atlas was in orbit.
The following day on 19 December 1958 the Atlas successfully reached orbit and for many years it was the largest object ever put into orbit with a weight of 8,660 lbs. The command channel to upload the President's message, however, was inadvertently triggered by a radio station in New England that by coincidence happened to be on the same frequency broadcasting a dance band. It took two orbits to get the dance band recording erased and the President's message uploaded. This was President Eisenhower's message:
"This is the President of the United States speaking. Through the marvels of scientific advance, my voice is coming to you from a satellite circling in outer space. My message is a simple one. Through this unique means I will convey to you and to all of mankind America's wish for peace on Earth and goodwill toward men everywhere."
Project SCORE made 34 orbits broadcasting Eisenhower's message repeatedly before the batteries ran out and the Atlas burned up over Africa just over a year later. Even though SCORE was more a propaganda victory for the United States, it was the first demonstration of the potential of space-borne communications relay. While the SCORE payload was active, more than 78 transmissions were made between the satellite and ground stations making it the first communications satellite in the world.
Roy Johnson as the prime mover behind Project SCORE was invited to autograph the side of the Atlas before its launch and after it success, he had commemorative plaques made, one each for the members of the "88 Club" that worked in secrecy in addition to their regular duties to Convair and the USAF.
Source: Atlas- The Ultimate Weapon by Chuck Wallace with John Powell. Apogee Books, 2005, p224-230.
Monday, May 3, 2010
When Herb Kelleher and Rollin King sketched out their idea for Southwest Airlines on a cocktail napkin, they both knew they were facing tremendous odds against the large airlines that operated in Texas already like Braniff, American, and Texas International. One of their weaknesses was a lack of airline experience which they solved by bringing aboard veteran industry executive Lamar Muse who started out in 1948 at Trans-Texas and worked at American, Continental, Southern, among others and most notably was president of Fort Worth-based Central Airlines before it was bought up by Frontier in 1967.
With the nascent Southwest still fighting legal battles to win the rights to start service in Dallas, Rollin King and Lamar Muse visited Pacific Southwest Airlines' San Diego headquarters in 1969 to meet with the president of PSA, J. Floyd Andrews and the airline's management. King and Muse put it to Andrews bluntly- PSA was a successful intrastate airline for 20 years and they felt that they had an analogous situation in Texas as PSA did in California- large cities separated by a distance that could make for a profitable airline flight. They needed PSA's help in learning the tricks of the trade to become a successful intrastate carrier against the stiff competition of the incumbents, much as PSA managed to carve out a niche in California against United and Western.
Andrews was flattered by Lamar Muse and Rollin King's request and asked his management to cooperate with Southwest completely and not hold back on any of the tricks PSA learned to become successful with a loyal customer base. Between court hearings to get Southwest airborne, Herb Kelleher himself made several trips to San Diego to examine the operations of PSA.
PSA's management was so enamored with the ambitious Texans that they even sold them pilot uniforms, transition training on the Boeing 737 (when it became clear that the 737-200 would be Southwest's aircraft) along with training for the customer service personnel for Southwest. Flight attendant training was observed, inflight practices and procedures were shared, and even station operations were explained to the nascent Southwest operation. Even the financing and marketing departments of PSA welcomed Southwest's personnel for training sessions. The training sessions for Southwest's personnel began in 1970 and Andrews even let Southwest's representatives fly the jumpseat to observe PSA flights. They would carry notebooks in which they noted everything the pilots and cabin crew did that was unique, from funny announcements to inflight contests. Southwest's first marketing people sat in PSA boarding lounges throughout California observing the service levels and the humor PSA's gate agents used on a regular basis.
The head of PSA's computer reservations department even spent time in Dallas helping Southwest get its own system up and running! Andrews even had all of PSA's training and service manuals reprinted for Southwest to use in its early days, removing "Pacific" from "Pacific Southwest Airlines" and substituting "Texas" for "California".
When Southwest inaugurated its first flight on 18 June 1971 from Dallas Love Field, they started out with 22 years of airline operations thanks to the tutelage and generosity of the everyone at PSA. Even though PSA disappeared into history in 1986 when it was bought by USAir, much of what made PSA successful in its first quarter century lives on today at Southwest Airlines.
Source: Poor Sailors' Airline: The Story of Kenny Friedkin's Pacific Southwest Airlines by Gary Kissel. Palawdr Press, 2002, p171-172.
Saturday, May 1, 2010
1981: "I'M AN ACKER BACKER" pins are on everyone's lapels.
1985: "I'M AN ACKER BACKER" pins are in everyone's trashcans.
For years labor negotiations at Pan Am were always cordial and easily managed by both managers and union representatives who both passionate about the near-imperial status of their airline. Labor strife? That's below us. Strikes? That's below us here an Pan Am, too. Usually new labor agreements were hammered out at some local bar down the street from Pan Am's landmark New York City headquarters building. But that changed from 1981. Was it the airline's new chairman, smooth talking Texan C. Edward Acker? Was it the infusion of the employees of National Airlines in 1979? Was it deregulation?
Historians argue about where the fall of Pan Am begins, but there's no arguing the dismal financial record that continued even with Ed Acker at the helm. In 1982 Pan Am set an industry record with a half-billion dollar loss for the year- of course today, in the paraparetic state of the US domestic airline industry, that's a good year. Loss after loss mounted as Pan Am found itself lacking decent domestic feed (even after the acquisition of National Airlines) and under siege from more savvy competitors both domestically and internationally. Acker pushed through pay cuts which at first were readily agreed to by the employees of Pan Am and agreed in principle to what was called a "snapback"- after a given period of time, the pay scales would be restored. Acker reneged on the snapback and court litigation started flying.
Of course, it's not just losses alone that sank morale at Pan Am. In 1984 Acker's negotiating representatives (led by Raymond Grebey- the guy who precipitated the baseball players' strike in 1981) did an remarkably efficient job at angering the various union leaders. And then there was an internal consultants' report commissioned by the board that blamed the airline management for an inability to confront its mounting problems.
First to break ranks and offer concessions was the pilots' union. But their lead wasn't followed by the other unions of the airline. The Transport Workers Union were fed up dealing with Grebey and walked out February 28, 1985. With the mechanics walking out in the first strike in Pan Am's history, the other unions, including ALPA, followed suit.
It was the strike the broke the morale of Pan Am for good.
Friendships ended as some returned to work after only a week- death threats were exchanged between those returning and those manning the picket lines. Pilots returning to work would get spit on by former friends, flight attendants found themselves socially alienated whether they stayed on strike or returned to work. By the time the strike was officially over as each union group hastily signed new contracts, the airline would be littered with the corpses and carcasses of broken friendships, damaged work relationships, and simmering resentment not just at fellow employees but directed at C. Edward Acker and his management team.
Growing up, Pan Am was one of those airlines that was in a category all of its own and I remember following the events at Pan Am in the newspapers. Pan Am wasn't just an American icon, Pan Am was THE American Icon. Ever since the 1920s under Juan Trippe and his successors, Pan Am was the defacto "other" State Department of this nation as it carried the US flag on the tails of its jetliners worldwide. Aviation enthusiasts talk about Braniff or TWA and their overseas destinations and operations, and while those airlines had substantial contributions to the history of US aviation and commerce, it always paled in comparison to the rich history implied by that famous blue globe.
The strike at Pam Am damaged that image. The shine, the luster of what was an iconic airline of what it was to be American and the expression of that history wasn't what it was after the winter of 1985. It wasn't the beginning of the end. It was another step on the road to the airline's shut down in 1991 but for a lot of folks like myself who grew up with the mystique of Pan Am, it was a big shock.
Source: Skygods- The Fall of Pan Am by Robert Gandt. Palawdr Press, 1989.