Here’s a fun video about early American jet engine development, made in 1952 and recently found in the archives and posted on the GE blog.
The Jet Race and the Second World War
Bell Aircraft was chosen to design and build the airplane which was to be mated with the first American-built jet engine: it was called the XP-59 Airacomet, and GE’s engine (a derivative of the Whittle W2B) was called the I-A. The prototype Airacomet was delivered to the test field via steam train (with the engine being kept in constant rotation at low speed because of concerns about vibration damaging the bearings), and first flew in October 1942. The Army Air Corps ordered 80 of them, but only 30 were delivered, with the balance of the production contract being cancelled because of somewhat disappointing performance and the incipient availability of better engines and airframes.
Meanwhile, the British had proceeded with development of their first jet fighter, the Gloster Meteor, powered by Rolls Royce Welland engines. The Meteor did not see any air-to-air combat during WWII, but it was used with success against German V-1 buzz bombs (“cruise missiles,” as we would now call them) and also ground attack and airfield defense missions during the last stages of the war in Europe. It would later serve in the Korean War with the Royal Australian Air Force.
The Planes of Fame Air Museum has a P-59 Airacomet and is restoring it to flying condition.
“There had been a US research project on possible turbine applications in aviation, but it was focused on turboprops and ducted fans rather than pure jets.”
It’s interesting to me, that pure jets did work out well for big power at reasonable fuel rates, and we are actually back to ducted fans as our big commercial power plants on our airliners. Pretty fancy ducted fans but that’s really what they are.
Cool video. Those hilarious ill-fated early attempts at flight never get old.
The ducts in those early turbo superchargers piped the exhaust back to the turbine.
Today’s turbofans use ducted fans, but they compress air and operate under the principles as that early engine.
An interesting side note is the fuel used in the turbines. Ohain had Reich backing, so was allotted all the high octane gasoline he needed, and that’s what the Me262’s used. Whittle couldn’t get aviation gas, as it was all rationed and allotted for Fighter Command in Britain, so he used what he could get, which was illuminating kerosene.
This is why the JPA fuel they put in your airliner today is kerosene based.
Ed,
They also used kerosene because it was cheaper and denser than gasoline. The ME262 used mostly diesel as fuel during its operational lifetime. It could use aviation gasoline, but due to its low density it could not carry as much and the Jumo 004 engine consumed it faster than it did diesel.
I read somewhere that the jet on the M3262 required a TBO of 8 hours because of the poor quality of the metal
Yes between 8 and 10 hours because Germany had very limited access to chromium, molybdenum, vanadium, and other rare specialty metals. What I think is amusing is the drastic improvements in performance made to both Whittle’s and the German’s engines once GE, Westinghouse, and P&W got hold of them. Especially GE.
The reason we’re seeing larger and larger fans on jet engines has to do with this equation:
Kinetic Energy = ½ mv^2 (m = mass and v=velocity)
To maximize the energy output (thrust) of the engine, you want to make as much air mass move through the engine as fast as possible. One way to increase thrust is to increase the velocity of the air through the turbines. This means making the turbines spin faster, which creates a lot of strain (a pulling apart force) on the components, or increasing the compression ratio, or both. This has a big payoff, however, because KE increases as the square of the velocity. Double the velocity and the thrust goes up by a factor a four.
The alternative is get more air mass moving through, which is where the fan comes in. In a high bypass turbofan, the torque from the jet turbine is used to turn the fan. That air flows around the turbine chamber and out the back. That explains why the modern turbofans on airliners have gotten so big, the bigger the fan the more air it moves.
Fighter jet engines don’t have that luxury. They have to be small, so they increase pressures and temperatures and fuel burn rates to get more velocity.
How does a Turbo Fan Engine CFM56 7 Work
https://youtu.be/_LaKlE2h3Jw
Haven’t read this but it looks interesting: UK vs US development of the Whittle W2B turbojet
http://www.enginehistory.org/GasTurbines/W2B.shtml
According to the Wikipedia article on the Airacomet, the restoration will use GE J-31 engines. As near as I can tell with the various nomenclature changes, this is simply the production version of the original I-A engine….which probably means the time-between-overhauls will be pretty small, although not as awful as the early German engines, given that GE was not limited in its use of critical metals.
There is a separate project to build several replicas of the German ME-262 jet; these are employing GE J-85s in place of the original Jumo engines—I doubt if any of the latter are available, and it wouldn’t make much sense to reconstruct new engines with an 8 hour TBO.
http://www.stormbirds.com/project/index.html
“it wouldn’t make much sense to reconstruct new engines with an 8 hour TBO.”
Well… unless your goal were Authenticity Ueber Alles.
(I can see everyone outside the most hard-core historical preservationists agreeing that a dimensionally-perfect engine with more modern materials giving a big increase in service life would be ok.)
The subject of GE and jet engines brings up again the biography of Gerhard Neumann, Herman the German, just lucky I guess.
It’s not about the jet engine development but it is a very interesting biography.
My review of Gerhard Neumann’s book is here.
I ran across the website for the Gerhard Neumann museum…looks like an interesting place. Especially focused on the F-104 Starfighter and the J-79 engine.
In addition to the mechanical efficiencies described by Michael Hiteshew above, the ducted fan/twin spool configuration has the advantage of being quieter and having a cooler exhaust flow than earlier designs. The air flowing around the engine mixes with the hot core exhaust gasses and reduces both the temperature and noise produced by the engine. Cooler exhaust is safer for ground personnel particularly in close quarters (like aboard ship), Quieter is always better, especially when airports strive to operate when the neighborhoods grow around them (like Orange County CA).
“when airports strive to operate when the neighborhoods grow around them (like Orange County CA).”
Slightly off topic but the OC sample is infuriating to me. The billionaire Newport Beach residents got their pet Congressman Chris Cox to get the El Toro Marine Air Station closed in a lunatic effort to make the John Wayne Airport move away from Newport Beach. They don’t like the planes taking off over their homes on the water.
El Toro was a base that had been there since 1942 and which had a great relationship with the suburban communities that grew up around it. It had national park to the east and the fighters could take off over those areas and avoid the residential ones. Airliners would require longer takeoff routes and would be far more dependent on the prevailing winds that blow off the ocean. Thus, even a civilian airport inland 5 miles would still send planes over Newport Beach. Anyone who has been offshore LAX during operations knows that was a fantasy.
When El Toro closed and the Marines were forced to move to Miramar, they lost 1500 housing units for dependents. There were none at Miramar. The base still sits there ten years later empty with all the hangers and other buildings slowly deteriorating. I get angry all over again when I see it. The left wing Mayor of Irvine is trying to make it a “Great Park,” to make sure it is never made useful.
Chris Cox wasn’t done f**king he public as he was Chairman of the SEC during the 2006-2008 economic collapse and completely missed all the warning signs. As if that wasn’t enough, they found another spot for him where he could be useless.
The Housing and Economic Recovery Act of 2008, enacted in July 2008, gave Cox one of five seats on the Federal Housing Finance Oversight Board, which advises the Director of the Federal Housing Finance Agency with respect to overall strategies and policies regarding the safety and soundness of Fannie Mae, Freddie Mac, and the Federal Home Loan Banks. In September 2008, the U.S. Congress passed and President Bush signed the Emergency Economic Stabilization Act of 2008, which placed Cox on the newly established Financial Stability Oversight Board that oversees the $700 billion Troubled Assets Relief Program.
Great career. The empty El Toro base reminds me of him every time I see it. Sorry for the rant.