Water Methanol Take-Off

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BearForceOne
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Water Methanol Take-Off

#1 Post by BearForceOne » Wed Mar 07, 2018 7:30 pm

So, I read something today that referenced a “water methanol take-off” in a HS748. I have a vague notion of how this works in auto racing. Was this a common technique and how exactly did it work? Is it strictly a performance thing or did it have other advantages?
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Pacqing
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Re: Water Methanol Take-Off

#2 Post by Pacqing » Wed Mar 07, 2018 8:59 pm

Mater meth is used to cool the combustion air, think being sprayed with a mist of alcohol on your arm, this results in denser air and more performance. I was sitting in on a ground run on a Merto 23 one winter night and the guy at the controls said watch this and switched on the water meth. The Garrets went vazoooom and the Tq went WAY up.
So if you're hot and heavy and need the extra Tq to get airborne you use water meth.
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Re: Water Methanol Take-Off

#3 Post by confusedalot » Wed Mar 07, 2018 9:25 pm

Lots of accidents have happened because of water meth, not because the system design is no good, but because of human factors.

The common error leading to accidents were maintenance personnel inadvertently using the waste liquid barrel to fill up the tanks instead of clean water meth. As dumb as it sounds, it actually really happened many times.

That was by far the most troubling element for using water meth for ex 748 drivers (ages ago) like me.

Also, not the greatest thing to use as far as engine life is concerned.
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Re: Water Methanol Take-Off

#4 Post by roscoe » Wed Mar 07, 2018 9:28 pm

Water Methanol as utilized with RR Dart engines has two functions depending on the engine model and rating. First is power recovery, to return the engine to its rated takeoff power in high/hot conditions eg HS748-2. Second, power augmentation (boost). Increases takeoff power to the rated output irrespective of temperature. An example, the RDA-10 in the YS-11. When the water-meth cut in during a power run on the YS, everybody knew it. the torque rise and sound was unmistakable.
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Re: Water Methanol Take-Off

#5 Post by BearForceOne » Wed Mar 07, 2018 9:47 pm

confusedalot wrote:
Wed Mar 07, 2018 9:25 pm
Lots of accidents have happened because of water meth, not because the system design is no good, but because of human factors.

The common error leading to accidents were maintenance personnel inadvertently using the waste liquid barrel to fill up the tanks instead of clean water meth. As dumb as it sounds, it actually really happened many times.

That was by far the most troubling element for using water meth for ex 748 drivers (ages ago) like me.

Also, not the greatest thing to use as far as engine life is concerned.
Yes, I was reading about a HS748 that took off from Churchill back in 1982 and suffered a double engine failure in the climb-out. The crew put it down on a flat piece of ground outside of town by the old navy base (near the present day VOR). Apparently they found JP4 fuel in the water-meth tank.
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Re: Water Methanol Take-Off

#6 Post by RatherBeFlying » Wed Mar 07, 2018 9:48 pm

The Dart wasn't the first. ADI (anti detonation injection) was developed for recips in WWII and used in some piston airliners. I remember reading an ad on it in the late 50s.
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Re: Water Methanol Take-Off

#7 Post by fish4life » Wed Mar 07, 2018 10:29 pm

One of the big advantages of the water meth is just like when you enter a cloud it decreases the EGT. In some aircraft like a Metro you would temp out before you would torque out when it was warm so the water meth allowed the engine to produce full rated torque at a lower temp
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Re: Water Methanol Take-Off

#8 Post by CL-Skadoo! » Thu Mar 08, 2018 4:56 am

confusedalot wrote:
Wed Mar 07, 2018 9:25 pm
Lots of accidents have happened because of water meth, not because the system design is no good, but because of human factors.

The common error leading to accidents were maintenance personnel inadvertently using the waste liquid barrel to fill up the tanks instead of clean water meth. As dumb as it sounds, it actually really happened many times.

That was by far the most troubling element for using water meth for ex 748 drivers (ages ago) like me.
It never really frightened me.
I always took my ritual "quick sniff" and we were "two greening "on our way.
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Re: Water Methanol Take-Off

#9 Post by BMLtech » Thu Mar 08, 2018 7:52 am

Was involved with it on the Gulfstream 1 and some variants of the Convair 580 with the d13H engine had it for hot/high conditions. Pretty nasty from a maintenance point of view, highly toxic and fairly corrosive. Never looked forward to changing a water meth pump. Was heavily used on the first stovepipe jets on the 707/B52 etc. and those things rolled coal like you would not believe.
Fuel in water meth tank=total and near instant engine failure due to overtemp.
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Re: Water Methanol Take-Off

#10 Post by oldtimer » Thu Mar 08, 2018 11:01 am

The common expression used without water/methanol enhancement/restoration was "dry" take-off power or "wet" take-off power with W/M restoration. In the Metro 3, standard procedure for take-off was to stabilize power to 65% torque dry and then call for water injection whereby the torque would jump to 105% wet power with very little if any power lever movement. Normal rated power at ISA was 100%/1000 shp dry but with W/M wet power was rated to 110%/1100 shp, limited for 5 minutes. The 14,500 MTOW SA227 had to have 8 US gallons for a maximum effort take-off and the 16,000 MTOW airplane needed 9 gallons. The RR Dart 529 engine in the Gulfstream 1 was rated at 1910 shp dry power but 1990 shp with wet take-off power. That may not sound like much but remember in high or hot conditions, the engine will not make rated power dry. On a hot day, a wet take-off was almost like starting a third engine. In the AFM, there was no mention of a reduction in engine life with W/M use. In the G1, operators had to keep a certain amount of W/M in the wing tanks tp prevent corrosion of the metal parts. It would super clean the aluminum parts which would promote corrosion. The stuff was also flammable, expensive and toxic.
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Re: Water Methanol Take-Off

#11 Post by valleyboy » Fri Mar 09, 2018 6:31 am

with the large pistons it is used to prevent detonation as in the above mentioned race cars for example for the R2800 it took it from a 2000hp engine to 2400hp engine going from a dry manifold pressure of about 46-48 inches to 59 1/2 for takeoff - not common on C46 but piston convair and DC-6 cb16 power was standard
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Re: Water Methanol Take-Off

#12 Post by Rowdy » Fri Mar 09, 2018 10:45 am

It is massively corrosive! Methanol is also pretty freakin' flammable. It does a great job however in the proper mix at increasing the effective octane or reducing detonation (preignition) as others have described. It also burns fairly clean.

On the auto engines I've used systems on, the intact tract and valves are always nice and clean compared to the engines that aren't using it. I would say in those instances that they lasted longer as there was less thermal shock and detonation. The 2.2 Chryco turbo I have a system on makes almost 400hp at 22psi. My BMW made 440lb/ft torque wet. Only 385 dry. Could run 91 wet. Had to run 94 dry. Thats at a 50/50 mix with distilled water.

Never flew a machine with it.
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Re: Water Methanol Take-Off

#13 Post by pelmet » Fri Mar 09, 2018 4:11 pm

As mentioned earlier, misfueling(or miswatermethanoling) can cause an accident as happened an Avro in Northern Manitoba many years back. I believe it landed on a frozen river. That is why it is best to see what it smells like on the walkaround. It can save the day. One company had several aircraft with the wrong stuff in their tanks as the container used had the wrong stuff in it. Can you imagine three or four accidents in the same day as aircraft depart dry from the main base and do wet takeoffs at the out-stations...that was the quite possible scenario.

Plus, a new fuel guy once put fuel in the water meth tank. A sharp pilot saw some wetness from spillage and investigated further.

Something to think about if you use water meth.

It also had a min temp, so your best load carrying performance was the lowest OAT where you could use water meth, below that your load carrying capability decreased.
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Re: Water Methanol Take-Off

#14 Post by Siddley Hawker » Fri Mar 09, 2018 8:57 pm

The RR Dart 529 engine in the Gulfstream 1 was rated at 1910 shp dry power but 1990 shp with wet take-off power. That may not sound like much but remember in high or hot conditions, the engine will not make rated power dry. On a hot day, a wet take-off was almost like starting a third engine. In the AFM, there was no mention of a reduction in engine life with W/M use. In the G1, operators had to keep a certain amount of W/M in the wing tanks tp prevent corrosion of the metal parts. It would super clean the aluminum parts which would promote corrosion. The stuff was also flammable, expensive and toxic.
OT the F-27F had the same engine, 529-7E, 1910 dry/1990 wet.
The difference in performance wet or dry was considerable. Wabush airport is at 1800 feet elevation and in summer to get out of there with either the F-27 or G1 at MTOW it had to be a wet t/o. (And in the case of the F-27, flapless as well.) The pumps were submerged in the w/m tanks and you never allowed the tanks run dry as it would expose the pumps to air. I seem to recall there was a time limit of 12 hours of exposure and then the pumps had to be changed because of corrosion. You armed the w/m via overhead switches and it cut in at 14,200 RPM via quadrant switches as the throttles were advanced. It was a serious no no to hit the w/m arm switches once the throttles had been advanced. The US Navy operated the G1, and one crew inadvertently did just that once. They had been operating all summer doing wet takeoffs, and their procedure was to de-arm the w/m immediately after the gear was selected up. It was a cool day and they were coming out of Pax River dry. The Captain called gear up, and without thinking the copilot flipped the gear lever up, then reached up and shut off the water methanol. Trouble was they were dry so he actually turned it on, with the throttles wide open. They got the airplane around the circuit and back on the ground, but the story I heard from Flight Safety was the engine mounts had been torque twisted a couple of degrees
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Re: Water Methanol Take-Off

#15 Post by Ki-ll » Fri Mar 09, 2018 9:03 pm

If I remember correctly the extra power comes from not only methanol cooling the air charge but by also allowing more heat (fuel) to be added into the cycle.
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Re: Water Methanol Take-Off

#16 Post by pelmet » Sat Mar 10, 2018 6:32 am

Siddley Hawker wrote:
Fri Mar 09, 2018 8:57 pm
You armed the w/m via overhead switches and it cut in at 14,200 RPM via quadrant switches as the throttles were advanced. It was a serious no no to hit the w/m arm switches once the throttles had been advanced. The US Navy operated the G1, and one crew inadvertently did just that once. They had been operating all summer doing wet takeoffs, and their procedure was to de-arm the w/m immediately after the gear was selected up. It was a cool day and they were coming out of Pax River dry. The Captain called gear up, and without thinking the copilot flipped the gear lever up, then reached up and shut off the water methanol. Trouble was they were dry so he actually turned it on, with the throttles wide open. They got the airplane around the circuit and back on the ground, but the story I heard from Flight Safety was the engine mounts had been torque twisted a couple of degrees
Not sure if that was an exaggerated story or not. I have heard of one person doing this and the overtorque that can happen as someone mentioned about wanting to outclimb a significant cloud build-up one time. But maybe it is true. I believe the water meth is metered in when performed normally. Not sure what would happen if you reduce power, turn it on, then add power.
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Re: Water Methanol Take-Off

#17 Post by valleyboy » Sun Mar 11, 2018 10:52 am

The biggest difference I personally have encountered between wet/dry power was on the cv64 although maybe the 227 was the same - 3000 shp wet and 2000 dry. The bottom line - going from wet T/O power to climb power was a 50% loss in power (1500shp)
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Re: Water Methanol Take-Off

#18 Post by W5 » Sun Mar 11, 2018 6:19 pm

And you were not supposed to use it over +37 C on the CV640. Suuure.
Actually used it on the CV440 to below -40
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Last edited by W5 on Mon Mar 12, 2018 2:39 pm, edited 1 time in total.

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Re: Water Methanol Take-Off

#19 Post by valleyboy » Mon Mar 12, 2018 9:05 am

I think the most dramatic wet takeoff I ever did was in Farmington NM - high and hot - sucked wm tanks dry before 400 feet and engines surging on the takeoff roll - damn old hawker was too much arcticized -- haha - everything worked much better dry after that - no water available anyway.
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