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B-52 & C-17 Engine question for those in the know....


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Are the engines on the C-17 more powerful than the ones on the B-52? Meaning is one C-17 engine more powerful than the two B-52 engines that are paired together on the wings? If they are not, are there any other engines that have more thrust than the paired engines on the buff???!!!! thanx in advance for the help

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The TF33s on B-52H's are rated at ~17,000 lb static thrust. So 18 x 8 = 144, so the BUFF has approximately 136,000 lb static thrust available. The F117s on the C-17 have 40,400 lb static thrust each, so 40.4 x 4 = 161, 600 lb static thrust available.

The max takeoff weight of the B-52H is 488,000 lb, while the C-17 is 585,000 lb.

J

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Jennings,

Great answer. This means that a set of engines could be swiped out off a C-17 kit and grafted onto a BUFF for a hypothetical engine upgrade. Am I right Vindicator One?

I'm sure there are other options available as well, the CFM or Rolls engines in the A320/321 or 757 could easily be used too, as the max rated thrust on those is in the 50K range each.

I'm guessing the max take-off weight on the BUFF would be increased if an engine upgrade were ever done as a SLEP on the 52.

Cheers!

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That would be cool. The wings might not take that much thrust! You also have to consider the ground clearance.

Oh c'mon! It's a BOEING! We ain't talking no wussie Airbus here! :nanner:

J

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Jennings,

Great answer. This means that a set of engines could be swiped out off a C-17 kit and grafted onto a BUFF for a hypothetical engine upgrade. Am I right Vindicator One?

I'm sure there are other options available as well, the CFM or Rolls engines in the A320/321 or 757 could easily be used too, as the max rated thrust on those is in the 50K range each.

I'm guessing the max take-off weight on the BUFF would be increased if an engine upgrade were ever done as a SLEP on the 52.

Cheers!

Hey, I got to admit that you picked my pocket on dat one b'coz that's exactly what I'm thinking about doing to a 1/144 revell b-52 I got in da' stash! Jennings I wanna thank you 4 tha' answer 2 my query here. Also, has anyone thought about using the Apache exhausts on a CH-53 Super Stallion? Just throwin' this out 'dere is all?!!
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Hey Vindicator,

Didn't mean to steal your thunder. I've had one of those in the "planning" stage for years now but haven't gotten a round to it. My wife keeps swearing she is gonna buy one for me though (the dreaded ROUNDTUIT, from Home Depot)

Good Luck on that, can't wait to see some pics. By the way, are you familiar with the Dale Brown works? The Flight of the Old Dog? I've always wanted to do the EB-52 Megafortress from that series as well. Food for thought!

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There have been several proposals floated over the years to re-engine the BUFF with RB.211s (four) or with CFM56s (eight of 'em). I think there was even a plan to use JT3D-215s at one point. Not much more thrust, but newer technology (1970 vs. 1960). None ever came to fruition, and 50 years later we're still flying them with TF33s. The TF33 can trace its roots directly back to the J57 turbojet, which first ran on the bench in 1952! In case your math isn't up to scratch, that was 57 years ago this year!! A parallel would be if we had still been using the little four-banger that Wilbur & Orville made for their 1903 Flyer as a front line engine in 1960!!

J

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I'm not quite sure what the point of putting eight CFMs would have been. The CFM56-7 puts out over 52,000 LBS of thrust each. That's well over 200,000 total with just four engines. Does the BUFF really need to go from ~ 136,000 pounds of thrust of the eight TF-33s on the "H" to 416,000 pounds with eight CFMs?

There were also plans for a GE CF6-80A upgrade, 56,000 to 73,000# ea, in addition to the RB.211s

Edited by theemodelstarter
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The last study go-around at Boeing used the Pratt PW2040, pretty much the same engine as on the C-17. The big hurdle has always been the cost of programs. The last exercise looked pretty promising at one point, as it appeared the Air Force might be able to offset a large percentage of the cost with Federal money earmarked for pollution reduction!

As an aside, a few years back, Boeing was doing some certification work with the 777 here at Edwards. We used to provide ground support for them, and they were parked on the ramp right next to the old B-52B, 008. As the 777 taxied past for a test sortie, I mentioned to Dan, the Balls 8 crew chief, that one GE engine on the 777 was capable of producing more thrust than all 8 of our J-57's. Now, there's a picture for you. A single-engine B-52!

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The issue with re engining the B-52 has always come back to money. The thing is no one wanted to put more money into a plane that was going to be retired in a few years. The kicker is, every time we go to retire the B-52, It gets another extension...

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I found this photo on airliners.net, showing a TF39/JT9D attached:

20jju5c.jpg

It looks like ground clearance would've been an issue with these powerplants, especially the outboard mounts. I don't know how the wings would've stressed, for that matter.

Oh c'mon! It's a BOEING! We ain't talking no wussie Airbus here!

Even if this is a joke, please. The whole Boeing vs. Airbus thing can get ridiculous sometimes.

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If memory serves, I seem to remember a B-52 that tested the 747 engine. It had a 747 engine in the number 3 nacelle position. I can't find pictures now but I think there some on the internet.

B-52E's were used to test both the JT9D and the TF-39 for the C-5. A friend of mine was the test engineer on the TF-39 project. The pic posted above is the TF-39 installation. The JT9 was tested at Pratt's Plattsburg facility, not at Edwards. I have never run across a good shot of the Pratt airplane (JB-52E 56-0636) with the engine installed.

JB-52E 57-0119, the TF-39 testbed, is still at Edwards, out on the photo range. Unfortunately, it was pretty much demolished a few years ago and is pretty much just a pile of parts

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Begs the question of whether you couldn't possibly shorten the mounting pylons... give it something to keep the exhaust out of the way, or maybe cant the engines nose-up a little? I'm just trying to think if there isn't some way to fix the problem by adjusting the engine mounts.

Alternately - is the wing anhedral important, or could the wings be refitted without the anhedral in them to improve ground clearance with the new engines.

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Sorry, I meant TF34s from the A-10 and S-3.
Uh, no. The TF34s were proposed at one point for the EC-137D AWACS, not the Buff. (Doing the math, you'll find out that you'd need 16 TF34s to match the thrust of eight TF33s... I'd like to see some artwork on that layout! :rolleyes: )
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That photo shows a GE CF6 being certified for the DC-10, hence the shiny metal, pot-bellied nacelle. I'm not sure if it was the same B-52E that was used for both, but B-52s flew with both the JT9D and the CF6/TF39 at various times.

J

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I think the wing needs to flex or the plane would beat your brains out doing low levels! I would be a complete re-wing to remove the flex and anhedral. The B-52 has a very flexable wing. I'm sure the Buff would have gotten new engines already, if it was feasable.

Curt

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The only people it isn't feasable to are the beancounters - they keep seeing how old they are, how they aren't going to be in service much longer (at the time of the reviews) and red-stamp any plans to give them a major refit like that. Irony being, it gets shot down, they get extended. Beancounters like to say "if it ain't broke, don't fix it" and tend not to think about actually improving performance on a bird that's so long in the tooth it's dragging trenches at 50,000' altitude.

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The only people it isn't feasable to are the beancounters - they keep seeing how old they are, how they aren't going to be in service much longer (at the time of the reviews) and red-stamp any plans to give them a major refit like that. Irony being, it gets shot down, they get extended. Beancounters like to say "if it ain't broke, don't fix it" and tend not to think about actually improving performance on a bird that's so long in the tooth it's dragging trenches at 50,000' altitude.

I seriously doubt it's anything at all like this.

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I seriously doubt it's anything at all like this.

Quite so. If it were, the B-52 wouldn't have had the electronics upgraded, wouldn't be fitted for modern PGMs and cruise missiles, and probably wouldn't even have got the TF33 in the first place.

Harking back a few posts, there are two sizes of CFM56 - the big one for the long-range A340, and the little one for the 737 and A320. So an eight-CFM56 B-52 would be in the region of 50,000lb thrust on each pylon, which is about what the RB.211 proposal suggested.

The schematics for that proposal worked without changing the wing geometry, so ground clearance is unlikely to be a problem. Bear in mind that, large though the RB.211 is, it's still much smaller than the current range of 100,000lb engines, and the B-52 actually has a lot of daylight even under the outer engines. I suspect the major engineering work would be on the pylon, to allow for the extra thrust. A four-RB.211 fit would be the easier option to model in 1/144 because the engines are readily available from 747 kits (assuming they don't all have JT9Ds or CF6s). A final thought on this - the B-52's wing is anhedralled for aerodynamic reasons, so raising it would be a very bad idea.

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