Is water injection a redundant technology?
The F-105 (J-75) had a water injection system. Its sole purpose was to increase takeoff thrust and any residual water was dumped after takeoff. Had nothing to do with high speed flight, of which the aircraft was reasonably capable.
However, takeoff rolls were generally pretty long regardless.
edit: To be accurate, you could feel it when the water 'kicked' in, but it was more like a nudge than a kick.
However, takeoff rolls were generally pretty long regardless.
edit: To be accurate, you could feel it when the water 'kicked' in, but it was more like a nudge than a kick.
Last edited by OK465; 20th Jul 2017 at 14:59.
Since this topic is in "military aviation", I'm assuming at least one military jet used water injection to combat high inlet temperatures for high speed flying.
Mechta,
It's been awhile and my books are stashed away with the black widows in the attic, but I believe the water switch, which was just forward of the throttle was only enabled with the AB engaged. So when AB was disengaged the water was terminated anyway. Only used it a couple of times just to check the system was still functional. And in fact the water might have been used up prior to AB termination under some circumstances but you couldn't be sure.
The long toggle switch was a 3 position, On, Off, & Dump to both clear and prevent the plumbling and container from icing up at altitude and get rid of the minimal residual sloshy weight I suppose. I don't remember the capacity.
There's a notable incident of an F-105G tail section being blown off on the runway at the old George AFB because the wrong fluid was substituted for water.
It's been awhile and my books are stashed away with the black widows in the attic, but I believe the water switch, which was just forward of the throttle was only enabled with the AB engaged. So when AB was disengaged the water was terminated anyway. Only used it a couple of times just to check the system was still functional. And in fact the water might have been used up prior to AB termination under some circumstances but you couldn't be sure.
The long toggle switch was a 3 position, On, Off, & Dump to both clear and prevent the plumbling and container from icing up at altitude and get rid of the minimal residual sloshy weight I suppose. I don't remember the capacity.
There's a notable incident of an F-105G tail section being blown off on the runway at the old George AFB because the wrong fluid was substituted for water.
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OK465: I think you may be underselling the Thud with faint praise!
Had nothing to do with high speed flight, of which the aircraft was reasonably capable.
Surely it was one of the fastest military aircraft at low level?
Had nothing to do with high speed flight, of which the aircraft was reasonably capable.
Surely it was one of the fastest military aircraft at low level?
We had a B206-L, the basic model with a C20 engine. It had a water-meth tank and we used "squirt" on takeoff , or sometimes just to hover on a hot day in Oz. Its use immediately pulled down the TOT, and allowed us to pull more power. Had to be turned off by 60kt, but by then we are well into translational flight.
Usually not needed for landing, as we had burned off enough fuel to be able to hover in TOT limits.
Usually not needed for landing, as we had burned off enough fuel to be able to hover in TOT limits.
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I'm fully aware of the piston engine usage of meth/water injection systems as I design and use them on speed record cars and would love the chance to take a shot at bringing the reno race crowd up to the current century technology but they all state "cash is a problem" so we likely won't see digital fuel injection on an unlimited for quite a while.
This jet used water injection to keep temps down but I don't see any "factory stock" military planes using it for the same reason as other water injected jets.
This jet used water injection to keep temps down but I don't see any "factory stock" military planes using it for the same reason as other water injected jets.
At least one UK 206L had the system as I fitted it and removed it more than once.
Tank was on the forward wall of the baggage bay.
Always amused me that it needed water meth in the UK.
Tank was on the forward wall of the baggage bay.
Always amused me that it needed water meth in the UK.
Last edited by ericferret; 22nd Jul 2017 at 09:59.
Pratt and Whitney R-2800 and R-4360 used a 50-50 mix of water-methanol alcohol for ADI. At my company (Lockheed Aircraft Service) at Idlewild (later JFK) we bought it pre-mixed in 55-gallon drums. Someone in previous post said fish oil was added and may have been but our mix used Dromus oil. It is water-soluble oil usually used as a cutting fluid in machine shops. .
Flying Tiger at their Idlewild base apparently mixed their own ADI locally. One day the person making up the mix used deicing glycol instead of methyl alcohol. The first Tiger's DC-6A freighter getting this mix took off from Idlewild to the tune of backfiring. They lost further power and made a smooth landing on a mud flat in Jamaica Bay off the airport. The plane was partially immersed at high tide but it was retrieved, taken to Lockheed Air Service and repaired and returned to service.
Apparently, in WW-II the P-47 (R-2800) were modified for ADI use but had poor results. The Pratt and Whitney service representative found they were using ethanol alcohol and apparently it doesn't work. A switch to methanol fixed the problem.
Flying Tiger at their Idlewild base apparently mixed their own ADI locally. One day the person making up the mix used deicing glycol instead of methyl alcohol. The first Tiger's DC-6A freighter getting this mix took off from Idlewild to the tune of backfiring. They lost further power and made a smooth landing on a mud flat in Jamaica Bay off the airport. The plane was partially immersed at high tide but it was retrieved, taken to Lockheed Air Service and repaired and returned to service.
Apparently, in WW-II the P-47 (R-2800) were modified for ADI use but had poor results. The Pratt and Whitney service representative found they were using ethanol alcohol and apparently it doesn't work. A switch to methanol fixed the problem.
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The P&W R-2800 typically used around 10 lbs/min of ADI at TO power levels. The ADI was various combinations of water, methanol, ethanol, and a little bit of anti-corrosion oil. Each engine ADI tank held around 15 gallons. The fuel flow had to be adjusted based on the ADI mixture. Water does not contribute energy to the combustion process, and it displaces available oxygen in the intake charge mass flow, so the fuel mixture needs to be adjusted accordingly. Methanol and ethanol in the ADI does contribute energy to the combustion process, so the fuel mixture also requires adjustment to compensate for this.
To expand on Art Field's post #32. The Vaiant used water meth for take off only.
When initiated it increased the RPM by 300 from 8,000 to 8,300 with a constant JPT adding an extra 1,000 lbs. thrust to each engine..
The water meth tank was in the rear of the fuselage, held 1410 lbs. of W/M and lasted for one minute.
Precisely at the time the mainwheels left the runway at Nairobi International.
When initiated it increased the RPM by 300 from 8,000 to 8,300 with a constant JPT adding an extra 1,000 lbs. thrust to each engine..
The water meth tank was in the rear of the fuselage, held 1410 lbs. of W/M and lasted for one minute.
Precisely at the time the mainwheels left the runway at Nairobi International.
Yes, the present fleet of BUFFs are TF-33 powered, the J57 is gone everywhere. The KC-135s were the last J57-powered planes and they've been gone for two decades.
Republic, build a runway around the equator, we'll design a plane needing it for take-off". Only the C-5 needed more runway. A 1 minute roll and a run of 11,800' at LETO once.
GF
Republic, build a runway around the equator, we'll design a plane needing it for take-off". Only the C-5 needed more runway. A 1 minute roll and a run of 11,800' at LETO once.
GF
Impressive, and contributed to the local economy by resulting employment of hundreds to sweep countryside off the runway.
Is it the Metro's fitted with the Garrets that also use water-meth?
Is it the Metro's fitted with the Garrets that also use water-meth?
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When I did the MK1 Andover course in the 1960's, we were told the watermeth system was only to be used when absolutely necessary because of weight, temperature or altitude considerations. I think most of us used it a lot of the time for the extra thrust it gave on take-off and initial climb, but never on a check ride unless we could absolutely prove it was necessary.
Traffic #56
Yes, Garrett, now Honeywell, TPE331 on Metros and Jetstream use water/meth in summer in Australia. It is a 45% mix. I cannot remember the capacity or the usage rates for the Metro III but we used about 4 x 205 litre drums each summer.
Yes, Garrett, now Honeywell, TPE331 on Metros and Jetstream use water/meth in summer in Australia. It is a 45% mix. I cannot remember the capacity or the usage rates for the Metro III but we used about 4 x 205 litre drums each summer.
