WW II Water-Injected Engines

Ok, so it did not add HP, but was used during full throttle to cool engines. When is the water injected? If it is during the firing stroke, wouldn't it mess up the fuel / air ratio? Also, wouldn't the steam increase pressure?

I know that there is a reason that there are no new cars going down the road with a steam / ICE hybrid, I just am curious what it is.

I worked in fuels in the Air Force and nobody I asked could tell me much about the B52's I fueled at Barksdale other than that it used to be held in the outboard wing tanks and was used mainly for takeoff. The demineralized water used to be part of my career fields responsibility, but nobody knew how the turbines used it.

It would be my thought that any water injected into the turbines would flash into steam and increase the volume of exhaust gasses, but I wouldn't begin to know how or if this would result in increased thrust as well as cooling the engine.

I know during the transition from one model B52 to the next some engine upgrade made the water injection obsolete.

Weight wise, when a B52 can carry over 300'000 pounds of JP8 (at 6.8 pounds/gal) I doubt it noticed the weight of a few thousand gallons of water.

This pic shows the large water tanks on the wings. Later models had smaller tanks for fuel.

Drew

In the automotive applications I am familiar with, the water was metered in to the air stream above the throttle plates, so the term water "injection" may have been something of a misnomer. I don't know about increased pressure from the water vapor, but I do know, based upon the combined gas laws that, if you decrease the temperature, the pressure will be somewhat reduced as well, again allowing greater compression and/or boost. The idea was to get increased combustion chamber pressure at lower temperature.

With regard to turbines, I have to assume that the idea was similar, to generate higher exhaust velocities at lower temperature by increasing the pressure, so as not to slag down the engine. Of course with the advent of the new super-alloy turbines, much higher chamber temperatures are now possible.

GA from me for a really good answer.

But many (sadly) will not understand it and will talk about splitting H2O and things!!!!! Which is of course rubbish!!!

ADI I think is the name of the liquid. Cooled engine and increased compression. Typically utilized at take off.

Water weighs 8 pounds a gallon.

Gas weighs 6.4?, JP4 what, 6.8.?

Weight is important when flying. Another tank? More weight?

Water is heavy.

Better engine; better.

Better engine; better.

Well put.

A couple decades ago, I developed pilot training systems systems for the Fokker F27, which still used water injection for hot takeoffs. Even then, water injection was considered pretty much out-of-date.

It seems smart to me to use the waste heat in an engine.

It is, but that is not what water injection does. Water injection has been used with piston engines to reduce detonation from high compression. In turbines it cools engine components so that higher power settings can be used (although only briefly, typically).

In piston engines, it's effect varies somewhat depending on the rate and location of most of the evaporation. Evaporation in the intake track cools the incoming mixture, allowing a greater mass (for a given volume) of mixture to be inducted. This could have the potential for increasing power, if detonation could be controlled. The second, more important, effect is to cool the mixture as it burns in the cylinder. The heat of evaporation is extracted from the heat of combustion. This would, by itself, reduce power -- add enough water and you can put the flame out all together. But cooling the burning mixture reduces the propensity for detonation, so higher compression can be used with water injection than without. Therefore, if you have done things to the engine to make high octane gas a requirement, but don't have high octane gas available, then water injection could be helpful.

Modern turbo cars change timing and reduce boost when running on low octane fuels. Water injection could enable these cars to perform a little better on low octane fuel, but at considerable system cost, and at some inconvenience.

The six stroke engine uses waste heat to provide some steam power. This is quite different than water injection because the heat of evaporation is not extracted directly from combustion heat, but instead comes from cooling the engine -- which has to be done anyway to keep it from melting into a blob.

Why has water injection been largely abandonded? Better engines, better engine controls, better (and more consistently available) high octane fuels.

Most IC engines in the US have engine control computers which monitor the engine for detonation/pinging and adjust the ignition timing and fuel/air ratio to eliminate it. Thus there is no need for water injection.

Hi,

there was an accident with a civil airplane near 1970 at Hamburg/Germany. Immediately after start within a few minutes all turbines failed. The pilot succeeded to make an emergency landing on the nearby Autobahn, saving most of his passengers lives.

The maintenance people had erroneously filled the water-tanks (used for cooling at start) with fuel. Overheating gave a turbine life to failure of near 5 minutes!

RHABE

I agree was said uphere for gasoline engines and why better fuels and better ways to match them with modern engines.The best picture i could copy for recent development from LORANGE (M.BENZ division company,specialized in injection system for ci engines)of this dual injector for large engines:to reduce contamination.

Hello All,

This is a very interesting discussion line and I just want to add some observations from years long past.

Water injection in the USAF didn't end with newer versions of the venerable B-52 BUFF.....presumably you folks meant the later versions of B-52 (G/H mods) built in 1960 through 1962. If I'm not mistaken, the earlier B-52 (up to the D mod) utilized the J-57 turbofan engine with the water injection.

Every year I used to attend the Commander's Day Open House at both Griffiss AFB in Rome, NY and at Plattsburgh AFB in Plattsburgh NY until those bases closed in the early to mid-90's. Back even in the 1990's, the KC-135E Stratotankers still had the J-57 engine like those used on the early BUFFs. They also used the water injection principal during take-off on hot days. It's a sound that you'll never forget the rest of your life! Man, those J-57 engines really screamed when water injected!!! I still have 8mm videotape of those takeoffs and they were much louder than the the BUFFs and the FB-111A SACVARKS with their TF-30 engines on takeoff!!!! Ahhhh, the good old days of RAW JET POWER!!!

OF course, once the older KC-135 tankers were converted to "R" mod (in the 80's throughout the 90's) with their new high bi-past fan engines the water injection procedure in the USAF ended.

Just though you guys ought to know this..........

The AWACS KC135E model still had the smaller louder engines that looked like the B52 engines in the early 2000's (not sure if they still do). But I am pretty sure there was no water injection after I joined in the late 90's because there were fuels personnel who knew about the demineralized water plant.

I will never forget the sound of the B52's going right over my house when stationed at Barksdale. Even though I lived a half hour from base, I happened to be on some low level flight path and they would shake the dishes in my cabinets.

Drew

Hello Drew,

Thanks for reminding me about the USAF AWACS engines. I forgot all about them! Probably the reason why the AWACS doesn't employ water injection is because they aren't lofting all that fuel load like a KC-135E Stratotanker??? I honestly don't know if the USAF swapped-out the old engines on the AWACS aircraft for the high bi-pass fans built by SIMCA (sp?).

I hear ya on the noise of a BUFF climbing out! hehehehe the Sound OF FREEDOM!!! Ditto with a B-1B with those 4 massive GE F-100 engines!!! yousers!!!!! Ya come away from the encounter with an ear ache for sure!!! LOL

I was once backpacking up Giant Mountain in the High Peaks Region of the Adirondacks in upstate NY with a former girlfriend. We had just sat down after reaching the summit and began eating our lunches when all of a sudden out of the valley below came a pair of FB-111A's in full military power doing their "Nap of the Earth" thing! These birds were flying out of Plattsburgh AFB, a SAC base. They passed right over us no less than 150 feet AGL doing at least 500 knots with swing wings fully swept back! After passing over us (and several other hikers) they dived down into the next valley and then over the next ridge.....what an impressive sight to see, hear and feel!!!!!! Neither of us could really hear much for the next few days probably because we experienced close to 120 to 130 dB's!!! This was back in the mid-70's when there we're and flight restrictions on USAF aircraft over the Adirondacks per see.

Another impressive sight I saw when I was 16 years old and out on my cousin Greg's boat fishing the Sacandaga Reservoir at 5:30 on the morning. The reservoir is located in the southern portion of the Adirondack Park in New York state about 45 miles northwest of the state capital of Albany. Remind you that this was 1974, at the height of the Cold War and the near end of the Viet Nam War. We were anchored about 200 yards away from the Bachelorville Bridge which crosses the lake. I remember that the water level was quite low that year and we had to watch out for rocks more often than we usually had to. It probably was at least 20 feet or so lower than it had been in late May. Just after we had anchored and gathering our fishing poles a pair of FB-111A's came screaming down the over the lake coming from the large portion of the lake, say about 50 feet above the water surface. They had to be doing at least 600 knots easy! You should have seen the roster tails being kicked up into the air by their jet engines!!! UNFREAKING BELIEVEABLE!!!! Well, the lead aircraft actually went under the bridge arch with not too much room to spare. THAT WAS ONE CRAZY-ASSED PILOT!!!! I felt sorry for the WSO sitting next to him...he probably barfed up breakfast then and there! (LMAO) The lagging aircraft climbed up and over the bridge then dived ever so slowly down to towards the water surface....much have been Napping Earth! Both aircraft passed by us about 250 to 300 yards and the sound was so great it actually rattled to death and finally broke one of the wind screens on the Cristcraft boat we were in. No time to prepare our ears or cover them up either!!!!! OUCHHHHH!!!!!!!!!!!!

Later on after we returned to the camp we told my aunt and uncle what we ad witnessed 3 hours earlier and they didn't believe us!!!!! Thank God their next door neighbor came over later to tell them all about the sighting. The neighbor and his 8 year old son had been fishing off the wooden dock that morning and had seen it happen too! Felt vindicated after his report! Glad I was there to see the impressive display of air-power at its finest. I doubt I'll ever see such a thing the remainder of my life!

===captainmoosie

I think you'll find water injection was used briefly on a production car. I think an Olds F85 (that had a Rocket V8?) used it. I remember them selling (Rocket Fluid ?) for it. Does that ring any bells or am I hallucinating again?

According to Wikipedia, you are correct sir. From 61-63, Buick and Oldsmobile produced a 215 in³ all aluminum V-8 for use in their smaller cars. The Buick version also showed up in some Pontiacs. The Olds version was

Anyway, in 62 and 63, Olds produced a turbocharged high-compression version of the 215 V-8 in a special F-85 Jetfire. And it did include a water injection unit to control knock in high throttle situations. The fluid was a mixture of distilled H₂0 and methyl alcohol and was dubbed "Turbo-Rocket Fluid".

That's right!

I once bought a normally aspirated 215 powered Buick Skylark to use the engine in an MGA. (The aluminum Buick and the cast iron MGA engine were essentially the same weight.) But I haven't thought about the turbo model in ages... and it did have water injection. (Which makes me wonder if the Corvair turbos of the same era might have had it... a search indicates not, but it also indicates that there is still interest in hopping up Corvairs.)

And how do you think about "Vitameter" or "Vitol"?

I was young & stupid-naturally v8,s- salesman said will increase mpg from 12 to 26 mpg- my mate did it!- so paid & fitted- never worked- later came a tube into venturis in carb -did nothing till day I parked with engine off, engine lower than normal- water lock- bent con rods- engine finished. then souped up Ford Cleveland - wouldn"t run w/o detonation on accel- using super fuel- cure was either my solution of a manuel advance lever turning distrib body- or just as good- a windsreen washer pump thru a jet into top of aircleaner using a mom switch when accel. The water inj slows down rate of burning- no more power.

There is an article in Wikipedia about the 6-stroke cycle internal combustion engine, which might make interesting reading, perhaps?

http://crosleyautoclub.com/EngineTree/QuickSilver.html

http://books.google.com.ar/books?id=O6VUEkbqZ2QC&pg=RA1-PA149&lpg=RA1-PA149&dq=vitameter&source=bl&ots=YSMzgsmcnu&sig=MuDJn4D4BJPve4r3P1xPJZLtFBQ&hl=es&ei=L1QmS_KUHYOVtgfUmMTjBw&sa=X&oi=book_result&ct=result&resnum=4&ved=0CBgQ6AEwAzgK

Thanks. Interesting history.

The Crosley article correctly makes that point that the water injection system (actually water/alcohol/tetra ethyl lead) was of no use on the standard low compression engines.

I've a friend who has been very active in the development of turbocharger systems for motorcycles. He said that his dyno testing work indicates that water injection is a wash (no pun intended). It does not increase power by itself but it does allow an engine to use higher levels of boost without detonation which does increase power.

That is exactly true and the reason why it has been used since someone first thought of it!!