Comments on: Back to the Drawing Board http://www.defensemedianetwork.com/stories/back-to-the-drawing-board-the-big-and-not-so-beautiful-vultee-xp-54/ Your Source for Defense and Military News Mon, 06 Feb 2012 14:18:58 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: Chuck Oldham (Editor) http://www.defensemedianetwork.com/stories/back-to-the-drawing-board-the-big-and-not-so-beautiful-vultee-xp-54/#comment-82 Chuck Oldham (Editor) Fri, 19 Feb 2010 15:59:36 +0000 http://theyearindefense.com/?p=1496#comment-82 Interesting thing about the Lycoming it was completed with: it was an H-24 engine, basically two opposed 12-cylinder engines sharing a common crankshaft. Hawker's World War II Typhoon used basically the same set-up in its Napier Sabre engine, but with sleeve valves, which added massive complexity and made for early unreliability. I don't know how reliable the Lycoming was, because it was never mass-produced and there don't seem to be many records associated with its development. The 37mm cannon had a trajectory like a rainbow (I'm exaggerating a little), which is probably why they felt they had to design such a needlessly complex nose. If you haven't read Edwards Park's Nanette or Angels 20, you should check them out. In addition to being great books, Park describes flying the P-39 Airacobra armed with that 37 mm cannon, and the problems with aiming and firing it. Pilots apparently preferred the P-400 variant's 20mm instead of the 37mm, not least because of the 37mm's propensity to jam. I would bet that if development had continued, the XP-54's weapons package would have become more like what you describe. What I don't know, and wonder about, is the details of the ejection system. Saab seems to have gotten the concept right with the Saab 21. They even managed to use the same airframe when they switched from prop to jet power! Interesting thing about the Lycoming it was completed with: it was an H-24 engine, basically two opposed 12-cylinder engines sharing a common crankshaft. Hawker’s World War II Typhoon used basically the same set-up in its Napier Sabre engine, but with sleeve valves, which added massive complexity and made for early unreliability. I don’t know how reliable the Lycoming was, because it was never mass-produced and there don’t seem to be many records associated with its development.

The 37mm cannon had a trajectory like a rainbow (I’m exaggerating a little), which is probably why they felt they had to design such a needlessly complex nose. If you haven’t read Edwards Park’s Nanette or Angels 20, you should check them out. In addition to being great books, Park describes flying the P-39 Airacobra armed with that 37 mm cannon, and the problems with aiming and firing it. Pilots apparently preferred the P-400 variant’s 20mm instead of the 37mm, not least because of the 37mm’s propensity to jam.

I would bet that if development had continued, the XP-54′s weapons package would have become more like what you describe. What I don’t know, and wonder about, is the details of the ejection system.

Saab seems to have gotten the concept right with the Saab 21. They even managed to use the same airframe when they switched from prop to jet power!

]]> By: Tim http://www.defensemedianetwork.com/stories/back-to-the-drawing-board-the-big-and-not-so-beautiful-vultee-xp-54/#comment-81 Tim Thu, 18 Feb 2010 14:39:03 +0000 http://theyearindefense.com/?p=1496#comment-81 Interesting aircraft. Looks like it fell victim to the same things that affect today's aircraft; trying to do too many cutting edge things in one package. The basic airframe looks pretty simple and easy to mass produce. The air-cooled power plant in back doesn't make much sense to me as the required cooling ducts would cause drag. The weapons package could have been structured more in line with the P-38 using a combination of 50 cals and 20 MM avoiding the whole tilting nose thing. Some other combination of weapons might also have compatible muzzle velocities. With all guns on centerline it could have been a "dive strafer" used against lighter vessels, tanks, and vehicles.Staying away from pressurization avoids lots of combat problems when the aircraft starts acquiring holes and simplifies the ejection system. The gull wing sets up the airframe nicely for carrying big bombs, gun pods, belly tanks, or torpedoes under the belly. Not sure why the counter-rotating props were deleted with the new engine choice unless there were weight and balance issues. At its early stage of development engineering could have realigned the airframe to work with the new engine. Looks like it had good potential just fell victim to too much too soon. Interesting aircraft. Looks like it fell victim to the same things that affect today’s aircraft; trying to do too many cutting edge things in one package. The basic airframe looks pretty simple and easy to mass produce. The air-cooled power plant in back doesn’t make much sense to me as the required cooling ducts would cause drag. The weapons package could have been structured more in line with the P-38 using a combination of 50 cals and 20 MM avoiding the whole tilting nose thing. Some other combination of weapons might also have compatible muzzle velocities. With all guns on centerline it could have been a “dive strafer” used against lighter vessels, tanks, and vehicles.Staying away from pressurization avoids lots of combat problems when the aircraft starts acquiring holes and simplifies the ejection system. The gull wing sets up the airframe nicely for carrying big bombs, gun pods, belly tanks, or torpedoes under the belly. Not sure why the counter-rotating props were deleted with the new engine choice unless there were weight and balance issues. At its early stage of development engineering could have realigned the airframe to work with the new engine. Looks like it had good potential just fell victim to too much too soon.

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