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Water injection?

Old 15th Nov 2022, 17:35
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Water injection?

Do any aircraft use water injection nowadays? B-52Hs or other TF33-powered maybe?

When it was common -- when Pan Am 707s were leaving Heathrow in summer 1959, say -- how cool did the day have to be for them to do without water?

How pure did the water have to be? No dirt presumably, but was hard water okay?
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Old 15th Nov 2022, 17:42
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I believe it had to be demineralized water so hard water probably no good. For the very few water injected jets at airport where I worked the water was condensate collected from heat exchangers at a nearby power station.
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Old 15th Nov 2022, 17:50
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Still some Harriers flying. Do the latest varients still use water injection?
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Old 15th Nov 2022, 18:26
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Some Darts fitted to 748's had it but not many of those left now, the Indian built ones may still use it.
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Old 15th Nov 2022, 18:43
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Originally Posted by sandringham1 View Post
Some Darts fitted to 748's had it but not many of those left now, the Indian built ones may still use it.
Darts used water methanol not water, speys used demineralised water
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Old 15th Nov 2022, 19:15
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While water injection did a good job at what it was intended to do (cool the incoming air to keep peak temperatures down), it was really hard on the engine. In addition to the higher thrust settings and all the wear associated with that, the water didn't immediately atomize when injected - the impact of the water droplets deep in the compressor tended to erode the compressor blades (unlike at the inlet where the blades are designed to withstand some debris impacts, the compressor blades deep in the compressor assume all the nasty stuff has evaporated or been centrifuged out and are relatively fragile).
Very important to use reasonably pure water (demineralized or distilled) to avoid mineral deposits on the compressor blades - really messes up the aerodynamics of the blades, plus large deposits can shed causing downstream damage.
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Old 15th Nov 2022, 19:22
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I remember seeing a USAF EC-135H performing a very sprightly take off during a show at Mildenhall and the commentator (Airsound?) remarking on something being injected, but whether it was water or methanol I can't recall - there was an interesting moment at about 200' when some combustion could be seen and heard - "added son et lumiere" said our man on the mic... Might have been compressor stalls as I recall it pitched up a fair bit! Long time ago tho, J57 or TF33s, did they ever get modified with CFM-56s?

Wasn't the 707 known by some as the Water Wagon?
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Old 15th Nov 2022, 22:02
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I thought that jet engines with water injection had the water injected into the combustion chambers. This was to cool them to allow more fuel to be injected to increase the power output.
Turboprop engines with water-methanol injection had the water-methanol injected into the compressor to restore the power output.

If you make a mistake and use water-methanol on a pure jet engine you end up destroying the turbine blades, as happened to a BAC 1-11.
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Old 15th Nov 2022, 23:47
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Treadigraph, all KC-135s have been re-engined (at least the ones still flying) so I don't think water injection is still a thing for that aircraft.
Compass - at least the engines I was familiar with, injection occurred mid-compressor. Cooling the incoming air has an additional advantage of improving compressor performance while lowering the peak EGT so you don't melt the turbine.

Last edited by tdracer; 16th Nov 2022 at 00:00.
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Old 15th Nov 2022, 23:57
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Originally Posted by Compass Call View Post
I thought that jet engines with water injection had the water injected into the combustion chambers. This was to cool them to allow more fuel to be injected to increase the power output.
Turboprop engines with water-methanol injection had the water-methanol injected into the compressor to restore the power output.

If you make a mistake and use water-methanol on a pure jet engine you end up destroying the turbine blades, as happened to a BAC 1-11.
I don't recall a WaterMeth incident with a BAC1-11 but the PanInternational accident at Hamburg was caused by Jet A1 being added to the De-Min water tank.
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Old 16th Nov 2022, 00:03
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Metro Liners still use it. So do some guys with turbo Buicks with 3.8s and gmc typhoons. Usually a water/methanol setup. Same idea though. FYI, not all kc-135s have been converted to cfms. Some still use the smokers as do e-3s and other airframe derivatives of the kc.
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Old 16th Nov 2022, 00:42
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It has been a long time , but we used water methanol (ADI, anti-detonation injection) on the R-2800-CB16/17 on the Convair 440 and the DC 6.
I also recall using water methanol on the Darts on the Viscount 806X and the Convair 640. The Convair 580's that were with Frontier also had water methanol injection. We leased a couple of them, and they were different in that regard.

Most of the time we had barrels of water methanol available, but if there wasn't any we used straight water. It nede a flush afterwards.

I have heard of incidents with the Darts were the wrong fluid was used (in one case jet fuel, in another Varsol cleaning fluid); resulting in dual engine failures on take off.
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Old 16th Nov 2022, 01:01
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Originally Posted by Afrijet View Post
Metro Liners still use it. So do some guys with turbo Buicks with 3.8s and gmc typhoons. Usually a water/methanol setup. Same idea though. FYI, not all kc-135s have been converted to cfms. Some still use the smokers as do e-3s and other airframe derivatives of the kc.
Those don't have the original pure jet TF-33s. They were re-engined with JT3D low bypass turbofans (salvaged from scrapped 707's) back in the 1980s (there was a plan to update those to CFMs as well but it may well have been cancelled). The USAF E-3s were built with JT3Ds (NATO got CFMs on the original build). I'm pretty sure they're not equipped with water injection.
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Old 16th Nov 2022, 03:30
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Originally Posted by tdracer View Post
Treadigraph, all KC-135s have been re-engined (at least the ones still flying) so I don't think water injection is still a thing for that aircraft.
This was early 1980s I should think, I don't believe I attended the Mildenhall shows after 1987 or 88. Definitely not a CFM equipped aircraft.
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Old 16th Nov 2022, 03:31
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The C20B powered Bell LongRanger 206L is water methanol injection capable, used when power limited and gives a useful 50-80*C drop in TOT (IIRC) with corresponding increase in torque available.

Certainly reduced the need for Comp Washes when I flew one, but pure water/meth essential as already mentioned: not many around these days, though 👍
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Old 16th Nov 2022, 04:24
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Last encountered them when I did a loadsheet course for SAA around the late 80s I think. It was explained that there was big tank which would be emptied during the take off. Tank was in the wingbox area as had an open top as a closed tank would not allow the pumps to flow as fast. I seem to remember the figure of 3000kgs added if water injection was used but it was a long time ago.

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Old 16th Nov 2022, 10:03
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All water injection did for a BAC1-11 was make it noisier. No discernible effect on performance.
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Old 16th Nov 2022, 10:11
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The Pegasus engine in the Harrier (all versions) did indeed use demin water injection. It had 50 gallons (proper ones) and lasted c 90 secs (or c 3 mins with half flow mod), giving an extra 1500 lbs of thrust. Extremely useful in hot/high conditions as it reduced the JPT considerably for given rpm. I used to give a quick blip as the jet ran up the ramp (for mum!) which left loads for subsequent landing.

Very useful in the Farley Climb as the JPT could otherwise get pretty high with high rpm and low forward speed. It made the exhaust quite smoky and that was a bit of a give-away in a low-speed fight 😊

it was fun to turn up at a display and when asked how much fuel you needed, reply “Fine for gas thanks, just give me 50 galls of water!”

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Old 16th Nov 2022, 10:36
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Originally Posted by Mogwi View Post
it was fun to turn up at a display and when asked how much fuel you needed, reply Fine for gas thanks, just give me 50 galls of water!

Mog
Indeed Mogwi
At our final? Dunsfold Families Day the RAF kindly supplied 2 x GR7's for a display flight (Jenks ?).
We usually had 2 x Demin Bowsers - one with electric powered pump (for hangar) - the other with a single cyl Yanmar diesel for the flightline.
Meanwhile the diesel bowser had been sent 'oop north' without anybody telling us (situation normal then )
Anyway the 2 GR's arrived and requested water I said '' leave it with me'' and we went and collected as many extension reels/leads as possible - now I cannot remember exactly how far the a/c was from the flight line hut but it must have been 100/150 yards LOL - the electric bowser slowly filled up the tanks with us keeping a close eye on the ext leads,we didn't see any smoke but it took a while !
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Old 16th Nov 2022, 11:08
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Originally Posted by tdracer View Post
Those don't have the original pure jet TF-33s. They were re-engined with JT3D low bypass turbofans (salvaged from scrapped 707's) back in the 1980s (there was a plan to update those to CFMs as well but it may well have been cancelled). The USAF E-3s were built with JT3Ds (NATO got CFMs on the original build). I'm pretty sure they're not equipped with water injection.
TF33 is the military designation for the JT3D. The original pure jet engine was the J57.
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