Water Injection
Thread Starter
Join Date: May 2001
Location: Frankfurt, Germany
Posts: 143
Likes: 0
Received 0 Likes
on
0 Posts
Water Injection
I have a couple of questions that I hope someone will be able to answer regarding water injection systems as used on Engines such as the Rolls Royce Spey and P+W JT3
I understand this is in order to increase thrust for take off and is achieved by injecting water into the compressor inlet.
I am curious as to how much water is required to produce a significant increase in thrust. For example, is an increase in thrust noticeable simply when flying through cloud which presumably would have a similar effect.
Secondly is this technique still used? and finally is it necessary to take any precautions to prevent the water in the injection system from freezing?
I understand this is in order to increase thrust for take off and is achieved by injecting water into the compressor inlet.
I am curious as to how much water is required to produce a significant increase in thrust. For example, is an increase in thrust noticeable simply when flying through cloud which presumably would have a similar effect.
Secondly is this technique still used? and finally is it necessary to take any precautions to prevent the water in the injection system from freezing?
Join Date: Mar 2000
Location: Arizona USA
Posts: 8,571
Likes: 0
Received 0 Likes
on
0 Posts
Water injection used on the B707-100 series powered with JT3C-6 engines used 400 gallons of de-mineralized water in 2.5 minutes at takeoff power, which ran the tank dry...so no problem with freezing at altitude. This water injection supplied an extra 2000 pounds of thrust per engine, as I recall...been a long time ago. These aeroplanes (some anyway) were later fitted with JT3D-3B engines (fan) which eliminated the need for water. Also MUCH quieter...for the airport neighbors anyway.
Join Date: Mar 2001
Location: London U.K
Posts: 80
Likes: 0
Received 0 Likes
on
0 Posts
RR Spey used demineralized water and this was injected directly into the combustion chamber by a separate tube but part of the fuel spray nozzle 10 each eng -512-14DW. DW = developed wet.
On the 500 series Bac 1-11 a rear water tank could hold about 500 kg of water. Freezing was a problem and you had tables to use if you wanted to tank water, time in cruise temp at altitude, water temp on loading were considered. Water was a bit of a pain to load downroute so tanking was prefered. If you could not tank then you had to load barrels of water into the hold and pump it into the tank downroute with a portable pump/motor also located in the hold. This pump was stored in a box, and you would drag the thing out and plug the hose into the rear of the aircraft. The plug for the pump was inserted into a socket in the rear freight hold.
As far as perf went you also needed to use tables to determine the amount of water you needed to enable you to climb to 400ft (min flap retract). Again based on temps, airfield alt, and aircraft weight.
Best Rgds
On the 500 series Bac 1-11 a rear water tank could hold about 500 kg of water. Freezing was a problem and you had tables to use if you wanted to tank water, time in cruise temp at altitude, water temp on loading were considered. Water was a bit of a pain to load downroute so tanking was prefered. If you could not tank then you had to load barrels of water into the hold and pump it into the tank downroute with a portable pump/motor also located in the hold. This pump was stored in a box, and you would drag the thing out and plug the hose into the rear of the aircraft. The plug for the pump was inserted into a socket in the rear freight hold.
As far as perf went you also needed to use tables to determine the amount of water you needed to enable you to climb to 400ft (min flap retract). Again based on temps, airfield alt, and aircraft weight.
Best Rgds
The water used in the Dart was actually a mix of water and methanol alcohol, typically 60% - 40% water to meth. It was used to either restore power - as with the Dart 529, or boost power - as with the Dart 532.
The F-27 had two forty US gallon tanks, one in each aft nacelle, and the FH-227 had one tank, in the left nacelle. Depending on the ASC, the G1 had either two wing tanks, one outboard of each fuel tank, or one tank located in each wing fillet.
The F-27 had two forty US gallon tanks, one in each aft nacelle, and the FH-227 had one tank, in the left nacelle. Depending on the ASC, the G1 had either two wing tanks, one outboard of each fuel tank, or one tank located in each wing fillet.
Join Date: Nov 2001
Location: chelmsford
Posts: 1
Likes: 0
Received 0 Likes
on
0 Posts
As an engineering base for some of the few remaining 1-11's in the UK i found the comments above very interesting. one of the offshoots from the "demin water" era is that through my carreer with bcal, BIA, Dan Air BWA we must have provided the whole of europe , half of africa and a good deal of russia with a free supply of empty demin barrels. I would be interested to hear if any of these pop up in any unusual places. I will re-visit with interest
Join Date: Jun 2001
Location: In da north country
Age: 62
Posts: 452
Likes: 0
Received 0 Likes
on
0 Posts
Well, on the DC-6, we had water injection on the R-2800's, which gave us an added 450 HP per engine, by de-riching the fuel mixture,and enableing us to use 59 1/2 inches of manifold pressure to give us a mixture that produced more power. Worked good, but the pucker factor on take off was quite something about all those pistons trying to escape from the cowling!! and sometimes they did!!!!!
Water injection? what the hell is that?
Water injection? what the hell is that?
Yeh Peter, the Convair 340's and Martin 404's had the same thing. Called it ADI. Stood for Anti Detonation Injection, I think. Didja hear the one about "double clutch that mother******" Martin 404 in GSO? 
Join Date: Jul 2000
Location: Back in the USSR
Posts: 36
Likes: 0
Received 0 Likes
on
0 Posts
When using water meth as an ADI system, usually 60/40, this used to have 1% fish oil added as a lubricant - was this also present in the 45/55 mixes used in the RR turboprop engines?.
Gaz
Gaz
Join Date: Mar 2000
Location: Arizona USA
Posts: 8,571
Likes: 0
Received 0 Likes
on
0 Posts
Yeh Peter, 59.5 inches MP and 243 BMEP...those were the days. The water regulator "usually" worked OK...
Most operators today use dry takeoffs due to 100LL fuel, I believe.
And...no oil added to the water methanol for Dart powered aeroplanes.
Most operators today use dry takeoffs due to 100LL fuel, I believe.
And...no oil added to the water methanol for Dart powered aeroplanes.
Guest
Posts: n/a
CONAIR still uses ADI for all loaded takeoffs on its DC6's. The extra power allows about 6000 lb higher gross weight. Watching the water pressure lights on TO is of conciderable importance as even one full power TO with out water will severely damage the engine. Still and all the late model R2800 CB3 and CB16 engines are marvelous pieces of machinery. Nothing beats the growl of 4 of them at full song 
BIK_116.80 - Out of having no choice on one trip, I managed to get six take-offs out of the water/meth tanks. Suffice to say I turned it off pretty quickly after each take-off ... 
Join Date: Feb 2001
Location: A PC!
Posts: 594
Likes: 0
Received 0 Likes
on
0 Posts
The Hawker (BAe) Harrier also uses de-mineralised water injection, onto the turbine, to gain extra thrust for take-off and vertical landing. Very effective, too, although the GR3 only had 90 seconds worth available per flight.
It cooled the turbine, allowing higher RPM and fuel flow (and therefore more power) for the same stress on the back end of the engine.
It cooled the turbine, allowing higher RPM and fuel flow (and therefore more power) for the same stress on the back end of the engine.
Crickey! You know me?
Nah, it's too long a story to tell properly, but it's pretty funny so I might knock it up off line and post it here for a laugh later.
No, he wasn't arrested, but then again he was never a problem after that.
Nah, it's too long a story to tell properly, but it's pretty funny so I might knock it up off line and post it here for a laugh later.
No, he wasn't arrested, but then again he was never a problem after that.
Join Date: Nov 2000
Location: US of A
Posts: 32
Likes: 0
Received 0 Likes
on
0 Posts
From what I remember the water on the BAC 1-11 only served to allow you to make even more noise and give you a warm fuzzy feeling that you were actually developing more brute power. Oh God I remember those water takoffs from Sicily with 114 pax with their buckets and spades trying to get to Luton, scraping by FL 200 by about Pisa.
Tell the kids of today that and they'll never believe ya.
Tell the kids of today that and they'll never believe ya.
Join Date: Jun 2001
Location: In da north country
Age: 62
Posts: 452
Likes: 0
Received 0 Likes
on
0 Posts
I had no idea there were that many piston pounding propheads out there in cyberspace who remembered what fish oil and water pressure lights were all about. Boy, haven't we come a long way! Hey, is that a double shorted secondary???? shut it down!
Guest
Posts: n/a
Peter Ball
I agree. There are still plenty of folks out there who appreciate airplanes built when men were men and engines were round ! My airline frend thought I was nuts driving a greasy six when I could be flying some glass cockpit wonderplane. But I have glass cockpit time said I ... I have spent many hours peering at the engine analyser trying to figure out what the squigly lines meant
I agree. There are still plenty of folks out there who appreciate airplanes built when men were men and engines were round ! My airline frend thought I was nuts driving a greasy six when I could be flying some glass cockpit wonderplane. But I have glass cockpit time said I ... I have spent many hours peering at the engine analyser trying to figure out what the squigly lines meant