Water/Meth Injection
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Water/Meth Injection
I've been thinking throughout the day (quiet one for flying) and was wonder if the benefits of having a water/meth injection system on an engine was of any real benefit given complications with the system and extra weight + having to have one more substance to refuel with???
I could take a guess that as they are no longer installed (on new aircraft) that they were perhaps one of those things that was "a good idea at the time".
I could take a guess that as they are no longer installed (on new aircraft) that they were perhaps one of those things that was "a good idea at the time".
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The old Dart engine on the F-27 didn't have enough oomph. On some of the desert strips for performance a wet T/O was a must.
If I remember correctly the power from one wet engine was equivalent to two dry engines during T/O.
Nowadays you can get around 5000 SHP out of P&W 150's without the benefit of water/meth injection.
If I remember correctly the power from one wet engine was equivalent to two dry engines during T/O.
Nowadays you can get around 5000 SHP out of P&W 150's without the benefit of water/meth injection.
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You wouldn't get that much out of em. 10 to 15 % maybe. The advances in metallurgy and design have placed the usefulness of w/m at the bottom of the heap now. W/m was a good way of increasing hot/high performance, however today's engines have large amounts of reserve as far as temps go so not really a useful item anymore.
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Water Injection
TwinNDB,
Believe me, you don't want to mess with it! The system installed on the B-52 G-model seemed to fail when you needed it the most. It provided augmented thrust for about two minutes during heavyweight, high temperature/PA takeoffs. It was supposed to be enough to takeoff and get the flaps up at 2000 feet AGL. There were lots of instances where the system failed and flooded the engine and flamed it out. I'm glad never to use the system again. Fly safe.
Believe me, you don't want to mess with it! The system installed on the B-52 G-model seemed to fail when you needed it the most. It provided augmented thrust for about two minutes during heavyweight, high temperature/PA takeoffs. It was supposed to be enough to takeoff and get the flaps up at 2000 feet AGL. There were lots of instances where the system failed and flooded the engine and flamed it out. I'm glad never to use the system again. Fly safe.
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As for piston engines, on the P&W 2800 CB series engines, water injection was very necessary and very effective. At dry power, we'd produce 1950 horsepower per engine, when we did a wet takeoff, we gained 450 horsepower per engine. On a DC-6, we would gain 1800 horsepower on a wet take off, and we needed it too! I have vivid memories of takeing off from Miami International and going threw downtown Miami, 12 miles away, looking UP at the tops of the buildings. It would take 30 minutes to get to 9000 feet!
As for serviceing, not a big deal.
As for serviceing, not a big deal.
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Thanks guys. You gotta love Pprune dont you? You go to bed, get up in the morning and there's your answer!
Makes for interesting reading though. There are obviously some pilots out there who had nothing but hassles with it and others for whom it was the best thing since sliced bread.
The other thing that brought the question on was that about a year or so ago I was speaking with an ex 747 classic driver who had one of the injecting nozzles detach and got ingested into the engine - made a VERY BIG mess so I am told. This was before V1 so an abort was in order.
Any others out there like that?
Twin
Edited to add - I didnt even know w/m injection was used on piston engines, is there any more information on that out there and are these aircraft still in service?
Makes for interesting reading though. There are obviously some pilots out there who had nothing but hassles with it and others for whom it was the best thing since sliced bread.
The other thing that brought the question on was that about a year or so ago I was speaking with an ex 747 classic driver who had one of the injecting nozzles detach and got ingested into the engine - made a VERY BIG mess so I am told. This was before V1 so an abort was in order.
Any others out there like that?
Twin
Edited to add - I didnt even know w/m injection was used on piston engines, is there any more information on that out there and are these aircraft still in service?
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Yes indeed still used in some large round piston engines....and is called ADI (anti-detonation injection) and is used to cool the cylinders at very high (BMEP) takeoff power settings, instead of extra fuel. Added to the fuel-air mixture by the water regulator.
In addition, some jet engines in the past used water injection to increase takeoff thrust. Some early B707's used water injection with the JT3C-6 engines....the water used was de-mineralized and generally used up with one takeoff...about 2 and a half minutes. Worked OK...but was LOUD.
In addition, some jet engines in the past used water injection to increase takeoff thrust. Some early B707's used water injection with the JT3C-6 engines....the water used was de-mineralized and generally used up with one takeoff...about 2 and a half minutes. Worked OK...but was LOUD.
Depending on the mark, the Dart was either a restored or boosted power engine with the use of water meth. In either case water meth allowed takeoffs at higher gross weights because of the better single engine wet climb performance.
Operation was straightforward. You armed the system before adding power on takeoff, it cut in when the RPM reached a preset value and cut out when power was reduced below a preset RPM on climb. There was a time limit of five minutes at wet power on the engines I flew (Dart 529-7E/8E)
A typical mix would be 55% water to 45% methanol by volume.The stuff was highly corrosive and the pumps had to be kept submerged at all times. If you ran a tank dry and didn't refill it within a pescribed length of time, it meant a pump change. It was introduced into the engine via the second stage compressor, which was also where the air for the deicer boots was tapped. As a result, the deicer distribution valves could become contaminated. We always ran the boots a couple of cycles after every wet takeoff, just to clear the system.
Operation was straightforward. You armed the system before adding power on takeoff, it cut in when the RPM reached a preset value and cut out when power was reduced below a preset RPM on climb. There was a time limit of five minutes at wet power on the engines I flew (Dart 529-7E/8E)
A typical mix would be 55% water to 45% methanol by volume.The stuff was highly corrosive and the pumps had to be kept submerged at all times. If you ran a tank dry and didn't refill it within a pescribed length of time, it meant a pump change. It was introduced into the engine via the second stage compressor, which was also where the air for the deicer boots was tapped. As a result, the deicer distribution valves could become contaminated. We always ran the boots a couple of cycles after every wet takeoff, just to clear the system.
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To answer your original question, Twin NDB, Some of the W/M systems I have used are worth their weight in gold. On TPE 331 -3 and -10 installations, the published torque increase was 15%, enough to boost RTOWs by 500 lbs on warm days on short gravel strips. The actual W/M weight carried was less than 60 lbs. (one firing) On TPE 331 - 11 Metro III installations, the RTOW could ideally be boosted by over 1000 lbs on paved runways just under 4000 feet while conforming to ASDA, TODA, and TORA limitations. (climb performance was never an issue when wet) The minimum quantity for such an exercise would be about 60-80 lbs, and torque increase about 20%. Firing several times per day in summer for a few years and never seen a system failure, Reliability was good. Just one problem, very abrupt. The Dart 534-2 (I think) had a much smoother power increase/decrease due to slowly opening/closing injector metering units.
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TwinNDB
I asked a similar question myself a while ago. Got a wonderful set of answers and stories in reply.
Here is a link to the original thread...
Water Injection
I asked a similar question myself a while ago. Got a wonderful set of answers and stories in reply.
Here is a link to the original thread...
Water Injection
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Water meths
On the 748 water meths was used as a power boost for short runway t/offs, and to restore power on warmer days.
From memory power was increased by some 10%, from 2050 ish HP to 2280?
However I always thought that the psychological effects were greater than the physical, as indicated t/off torque increased from 300 to 500 lbs, and the noise level increased in a similar proportion!
I also flew the Trident 2e, but never used the rather unreliable demineralised water system fitted on that a/c.
From memory power was increased by some 10%, from 2050 ish HP to 2280?
However I always thought that the psychological effects were greater than the physical, as indicated t/off torque increased from 300 to 500 lbs, and the noise level increased in a similar proportion!
I also flew the Trident 2e, but never used the rather unreliable demineralised water system fitted on that a/c.
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I taught groundschool on the Convair 600/640 many years ago and these numbers stuck in my mind for the Big Dart engine.
Dry 2665 hp Max TGT 865C
Wet 3060 hp Max TGT 915C
I saw on ebay some selling AFM's for the CV640, otherwise known as the Convair 340D.
Ray
Dry 2665 hp Max TGT 865C
Wet 3060 hp Max TGT 915C
I saw on ebay some selling AFM's for the CV640, otherwise known as the Convair 340D.
Ray
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Slightly off topic, but if you are interested in the development of aero engines (it includes water/meth injection) have a quick look at this site I found, it's lots of text but it good reading.
http://members.aol.com/rogertiii/aircraft.htm
http://members.aol.com/rogertiii/aircraft.htm
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I am happy to say that our DC 6 is still running strong. We use wet power on almost every loaded t/o. The ADI mixture adds another 450 HP, and allows another 5000 lbs on take off. Luckily we are able to jettison our load in about 2 secs in the event of an engine failure. Wet power can also be called for on a three engine over shoot. Our company also flies the Convair and they use ADI as well, although in a different mixture as the six. No problems so far...
"Captain..she flies better on three empty than on four loaded!"
"Captain..she flies better on three empty than on four loaded!"
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The BAC 111 also had water injection for extra t/o performance
and any spare water left had to be dumped after t/o as no heaters fitted.
Remember the 111 where some oik filled the water tank with jet A1 (or methonal), the t/o was spectacular but it very soon became a large glider.
I don't think anyone was injured and I think it was in Germany.
Regards
and any spare water left had to be dumped after t/o as no heaters fitted.
Remember the 111 where some oik filled the water tank with jet A1 (or methonal), the t/o was spectacular but it very soon became a large glider.
I don't think anyone was injured and I think it was in Germany.
Regards
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Steamhead
Yes, you are right that the incident happened in Germany. The aircraft crash landed on the A215 Autobahn after both engines flamed out, because as you say the injection system was filled with Jet A1.
Unfortunately, the aircraft hit a bridge and burnt out. 22 people (including one crew member) out of 121 lost their lives.
Yes, you are right that the incident happened in Germany. The aircraft crash landed on the A215 Autobahn after both engines flamed out, because as you say the injection system was filled with Jet A1.
Unfortunately, the aircraft hit a bridge and burnt out. 22 people (including one crew member) out of 121 lost their lives.
Paxing All Over The World
I do not write from personal experience ... my nephew is a Cpt on Jetstream 41 in Africa. He says that the W/M is astounding and gives a heck of a kick. If memory serves, "It allows you to climb out on one if you have a failure at rotation - rather than ploughing fields."
However, he said that the company restricted wet t/o due to the extra wear on the engines. Sorry but I do not know what engines their J41s have. He did tell me but he told me sooooo many things about his shiny aeroplane that I could not possibly remember them all. Not least as I was too busy enjoying the jumpseat ride.
However, he said that the company restricted wet t/o due to the extra wear on the engines. Sorry but I do not know what engines their J41s have. He did tell me but he told me sooooo many things about his shiny aeroplane that I could not possibly remember them all. Not least as I was too busy enjoying the jumpseat ride.
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Steamhead
The 1-11 water injection system, those were the days! Remember the phone calls well around 0530. 8 barrels in the tank & sixteen in the hold for the return leg & destination re-stock. Knackered before the shifts even begun.
The 1-11 water injection system, those were the days! Remember the phone calls well around 0530. 8 barrels in the tank & sixteen in the hold for the return leg & destination re-stock. Knackered before the shifts even begun.