B-52 0008

http://en.m.wikipedia.org/wiki/Balls_8

 

Man... that doesn't seem like a lot of engine for all that weight and cargo....

Jedi

 

They just look so small to me!

Jedi

 

I have watched a handful of them fly by, and I have was always fastened by the B-52.

Thanks for posting Mark
VIA HTC SUPERSONIC CM7.2

 

it launched alot of test planes and bombs

 

I can understand the lowest hours seeing it's service.

But why lay it up.

Seems it's just broken in.

 

That's why there are eight of them. I worked on the XB-52 in 1951-53. The only and most powerful engines available then was the P&W J-57, 10,000 lbs. thrust. The J-75 wasn't developed yet nor was the TF-33 fan that powers it now. So, you are correct, they are small compared to the 13 foot diameter fans that they have on the 777. The J-57's were equipped with water injection and when that airplane took off with all eight at 100%, the noise and shock crackle was unreal. You could actually feel it in your chest. There have been several programs to change to newer and more powerful engines but the cost vs. payoff hasn't proved to be beneficial. Any engine change on an airplane, especially something entirely different, requires enormous internal changes to systems, structure, and sometimes aerodynamics. The B-52 power plant/airframe combination is still too compatible to mess with and it looks like the power that it has now and the availability of spare engines is a satisfactory situation.

 

I remember driving through (I think) Louisiana about 20 years ago and seeing a B-52 taking off perpendicular to the interstate I was on. What surprised me was the amount of dirty-looking black smoke it was trailing, as compared to the airliners I was used to seeing.

 

That would be Barksdale AFB in Shreveport, I-20 being the interstate. I went to college at Louisiana Tech which is about an hour east of there. We would see them fly over from time to time, always a great sight. Occasionally Tech will have them do pre-game flyovers before football games. I also seem to recall a couple of flyovers with A-10's accompanying them. In Shreveport proper you can often see them low and loud, and it is truly impressive.

 

That smoke is from engines that do not have the benefits of modern engine technology. It was an icon of the early jets like the B-52 and KC-135 that produced even more smoke when water injection was used. The KC-135 used 450 gallons of distilled water on take off. The B-52, twice that much.

 

I will never forget my first flight in a KC-135A. It was at Castle AFB. When the water injection started the noise and vibration was unbelievable. It was actually difficult to read the instruments. Then I looked out side and the jet had just barely started to move. It made my previous aircraft, the A-10, seam like a real hot rod!

 

Balls 8 replacement and the C-17 test engine platform.
Image Unavailable, Please Login
Image Unavailable, Please Login

 

A nice piece on 'Balls 8'

http://www.airspacemag.com/flight-today/mother.html

 

That's mostly due to water injection.

 

Jet engines are rated by static thrust. The thrust they make when strapped down and not moving. The first turbojets on the 52 and the later low bypass turbofans don't make as much static thrust as new higher bypass engines, but at speed and altitude, they don't have as high a lapse rate. The B52 was designed as a high speed, high altitude bomber, and up were it was designed to fly the old engines make a lot of thrust. Any old 707 pilot will tell that the JT3's would really push the aircraft at altitude, but it was hell geting it off the runway. When they went to fan engines they got off the runway faster, but they don't have as much poop at altitude.

That's where the water injection comes in. Not only does water injection increase the mass flow due to the mass of water, but it allows the compressor to move more air and it increases the pessure ratio of the engine. Since the air in the compressor is cooler, as a result of the water vaporizing, it takes less work to compress the air, and all of that ends up increasing the thrust. The engines on the B52 make 22% more thrust with water injection, that's a bunch more push. The higher pressure and higher flow out the back is what makes it a lot more noisy...

 

Exactly right. I used to make the east/west run on I-20 once a year or so back then.

 

ADI, Anti Detonation Injection is what it was termed at Boeing when I was working on the installation drawings. ADI prevented detonation, pre-ignition, flame creep, and raised the pressure ratio also by giving the effect of closing up the clearance between compressor blades and the case. You could increase the fuel air ratio without the combustion creeping up-stream from the combustion cans. That would also keep you from a high temp melt down. This is what I remember from from the power plant guys 55 years ago but I believe that you have a more succinct answer and explanation. Your comment regarding altitude performance reminded me of the comment made by a 720B pilot that " this damned airplane will run away with you at altitude if you don't watch power."
Thanks for your input.

 

This shows the amazing strides made in jet engine development since the '50s. Combine all 8 engines of the J57-powered B-52 and you get (without water injection) about 91,000 lbs of thrust. A single engine in most versions of the Boeing 777 develops more than that!

 

Nice thread and cool airplane. A 777 engine also has fan blades that are atleast 4 times bigger that the old J-57's. As they said the J-57 was made for high altitude speed, not fuel efficiency or low level performance.

 

Some nice images of "Balls Eight" here:

http://www.air-and-space.com/Boeing%20B-52.htm