Something Has Always Puzzled Me

[Gary]

I have often wondered about aircraft projects that have been shelved because the engines didn't work out. Take the XP-67 Moonbat. Such a cool looking bird, yet the silly arced engines kept burning up. Why in heaven's name wouldn't a project like that have continued but with Merlins, or license built Griffons? The list for this kind of thing seems really long.

Perhaps it's that I just don't understand how the engineering process works. However, the P-51 wasn't the sparkling performer it was before it got the Merlin. The Italians took several designs and strapped Damlier Benz engines and made some rather nice aircraft.

Jet projects seem to be even worse. There are so many projects that looked so promising that died supposedly because the power plants just didn't have the stuff.  

So I guess I am sort of asking two things. Why is it like that and can anyone add to these lists of wonderful yet forgotten projects that were still born because the engines stank?

Cheers
Gary

[Hobbes]

Swapping an engine isn't always straightforward. The new engine has to be a pretty close match in power, weight and dimensions.
Nowadays, there are so few engine manufacturers it's rare to find a good match. Around WW2, there were more engine companies. It's possible (but I'm not sure) the government dictated what would be built, this would tend to prevent overlap.  

[B777LR]

Just look at the difference between a P-51A and all other P-51s. If that much modification had to be done on the design, it would be even harder to modify a modern jet that goes 2 times faster than the P-51.

[GTX]

Swapping an engine isn't always straightforward. The new engine has to be a pretty close match in power, weight and dimensions.

And actually available - remember there is a limited supply of engines to go around.  Sure, everyone might like a Merlin or J-79 or F-135, but you can't always get what you want.  Sometimes, also the engine type is dictated to you.  Also, often, engineers will persist with a design long after they should have changed.  Finally, hindsight is always 20:20!

Regards,

Greg

[GTX]

As for failed (or less than hoped for) projects because of engines, just look at some of the US fighters etc from the '50s/'60s because of the engines such as the Westinghouse J46 or Westinghouse J34 or Allison T40.

Regards,

Greg

[John Howling Mouse]

You bring up a good point, Gary.  Often come across this when reading about the development of a/c, even those which ultimately become successful ones.
The F-3H or whatever Demon comes to mind.

And it would have been interesting to see superengined versions of everything from a BP Defiant to a Skyray.  A lot of the Fairey projects seemed seriousy inadequate when it came to comparative engine power, too.

Hmmm....GB anyone?

And I won't even bring up "Orenda Iroquois" and "Avro Arrow" in the same sentence...oops.

[kitnut617]

A lot of the Fairey projects seemed seriousy inadequate when it came to comparative engine power, too.

Like the Fulmar that morphed into the Firefly once it got the Griffon !!

[Madoc]

Gary,

I'm with you!

Particularly when it comes to all the R40C aircraft.  All those birds were pushers and they all came a cropper due to the failure of the Air Corps' "Hyper" engine program to produce its billed goods.  So, they all had off the shelf engines installed and that hobble the performance of all those wonderful prototypes.

So why didn't they slap some jet engines into the things?  As pushers they'd have been easy enough to adapt and they were already designed for higher speeds.  You'd think it'd have been a marriage made in heaven.

Thus, instead of developing entirely new airframes to wrap around those jets, the Air Corps could've taken designs that already had some large amount of development work behind them - having been flying with their inadequate piston engines - and got going with jets.

Just think of a Swoose zipping about with jet power circa 1943.  Or perhaps a Black Bullet screaming across the skies above Muroc then as well.

Ah, the possibilities...

Madoc

[jcf]

Basically, the XP-54 and XP-56 were too heavy for the early jet engines that were available.
The XP-54 would have required two engines, thus requiring a major redesign and the XP-56 something like an after-burning Ghost or Nene.

XP-54
Weight empty: 15,262 lbs
Weight loaded: 18,233 lbs
Weight max: 19,337 lbs

XP-56 #2
Weight empty: 9,879 lbs
Weight loaded: 12,588 lbs

for comparison:
Gloster Meteor Mk. 3
Weight empty: 10,519 lbs
Weight loaded: 13,920 lbs

DH Vampire F. Mk. 3
Weight empty: 7,134 lbs
Weight loaded: 11,970 lbs

Lockheed P-80A
Weight empty: 7,920 lbs
Weight loaded: 14,000 lbs

BTW Northrop wanted to turbo-supercharge the R-2800 in the XP-56, the Air Corps said no.

Jon

[MartG]

Hmmm - anyone else think "TF-30" when looking at the title of this thread ?

If it had performed as advertised maybe there would have been a lot more F-111s around ( 111B, 111K, etc. ) - and fewer F-14s may have fallen out of the sky

[elmayerle]

Hmmm - anyone else think "TF-30" when looking at the title of this thread ?

If it had performed as advertised maybe there would have been a lot more F-111s around ( 111B, 111K, etc. ) - and fewer F-14s may have fallen out of the sky

Well, if someone in the US could've swallowed their pride, SNECMA appeared to have cleaned up the problems with the TF-306 and retrofitting that derivative would've made sense.  Regarding the Tomcats, the TF30 was only supposed to be in the first 30 before they switched to the F401-powered F-14B.  Unfortunately, after some development problems, Congress cancelled the F401 on the grounds that "...the TF30 is good enough." (quote from Rep. Les Aspin (D-WI).  Of course, some years later when the USN has lost several Tomcats because of engine problems, this same Representative came out saying "The Navy bought a 'Turkey', not a 'Tomcat'!" but never owned up to his complicity in the problem.  (Me, bitter? Damn straight, the cancellation of the F401 brought me my first layoff - I survived that but his hypocrisy rather ticked me off).