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Trident Water injection

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Trident Water injection

Old 3rd Mar 2018, 22:32
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Trident Water injection

I'm writing a book about British commercial aircraft 1960-1980 and am trying to get some definitive data on the Trident 2 water injection system. The Spey 512W was the engine concerned. Can any other poor old soul remember dry/wet max take-off weights. how much the water weighed or the tank capacity?
Apologies to all BOAC pilots for mentioning the T word.
Thanks
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Old 3rd Mar 2018, 23:54
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Gripper

I wasn't aware it was a system that the Trident used, although having spent many years watching various departures I had begun to think that something like that could be a good idea.

The BAC 111 with Speys certainly did employ water injection on some models. There was a terrible crash when somebody decided to fill the water tanks with kerosene.

Out of interest I flew as an F/E for Qantas who used water on take off for their 747-200's when necessary. The sim was a nightmare when checking water failure on take off and/or engine failure. (as I remember one water tank fed the left two engines and another the right) In those instances the F/E called the shots and it was difficult.

I never did a water take off for real. After the sim details I'm very glad I was spared the reality.


Kind regards
Exeng
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Old 4th Mar 2018, 01:18
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I was told years ago that every time a Convair 880 took off from Heathrow using water, they had to start taking RVR readings.
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Old 4th Mar 2018, 06:22
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Try the heritage museum

They have a set of T2 MANUALS but you need to make an appointment. The old museum adjacent to uniform stores was great but they had some jobs worth on my last visit at waterside who wouldn't give me access. Suggest you email them first.
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Old 4th Mar 2018, 06:30
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From fading memory B707B/C dry MTOW Dry 334k lbs , 336K Wet but was such a long time ago. Had water for about 2 mins.
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Old 4th Mar 2018, 07:46
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Originally Posted by Gripper123 View Post
Can any other poor old soul remember dry/wet max take-off weights. how much the water weighed or the tank capacity?
As I recall it the water was used to extend the Spey's flat-rating to higher ambient temperatures, rather than increasing the maximum thrust. It follows that the MTOW did not change.
Can't remember tank capacity but as, unlike the 1-11, the Trident did not use water in the missed approach only the amount of water needed for the take-off was loaded and it was all used.
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Old 4th Mar 2018, 08:17
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IIRC the Spey 512-14DW on the BAC One Eleven 475 and 500 was 12000 lb st thrust Dry and 12500 lb st thrust Wet.
I was a sometime flying spanner on the SOAF -475s and they would often be DRY out of Muscat at 35 C and wet out of Hurn, UK at 10 C due to the 6000ft runway.
It wasn't a lot of extra thrust but every little helps.
I seem to recall the typical fuel flows at T.O. power were 7,000 to 8,000 lbs/hr dry and > 10'000 lbs/hr wet ( the FF needles went off the top of the scale).
The Demin Water tank held 110 imp. gallons and this would last about 2 mins.
This means that there was more water than fuel going into the engine on a Wet T.O.
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Old 4th Mar 2018, 21:02
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unlike the 1-11, the Trident did not use water in the missed approach
On the 1-11, we used to dump the remaining water soon after take-off. Otherwise it would freeze in the cruise.
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Old 4th Mar 2018, 21:36
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Originally Posted by ZeBedie View Post
On the 1-11, we used to dump the remaining water soon after take-off. Otherwise it would freeze in the cruise.
That's why it was usually water-methanol, rather than simple de-min water, on 1-11s of course.
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Old 4th Mar 2018, 23:52
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Trident 2 and BAC 1-11 used only de- min water never water meth. Dart engines were the only civil engines that to my knowledge used water meth. On Trident it was dumped in flight.
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Old 5th Mar 2018, 05:25
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A little further info on water/watermeth injection. On the RR Dart the water meth was injected into the first stage compressor,the methanol burned in addition to the fuel in the combustion chambers to keep the temperature up.On the RR Spey the de - min water was injected to the rear of the compressors and the CASC unit (just a fancy name for the FCU.)was uprated in wet mode to increase the fuel flow. I once observed a watermeth power check on a Viscount where the supervisor performing the engine run forgot to switch the pump on and at max dry power he reached over and switched it on - the result was a tremendous roar and the engine wound down with water meth pissing out the intake and exhaust, the water meth control unit would have been trying to restore the power but having no flow would have been wide open so basically poured so much in it put the fire out. No immediate damage was done but i often wondered if the thermal shock had any consequences.
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Old 5th Mar 2018, 08:41
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The Paninternational 1-11 was doomed because it only had one water tank feeding two engines. I suppose if the 1-11 had two tanks the idiot would have still have put kerosene in both, but I thought it a strange design even so.
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Old 5th Mar 2018, 08:54
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ZeBedie,
According to BAC documentation from that era, the 1-11 water tank was in the pressurised hold so not subject to freezing.
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Old 5th Mar 2018, 09:56
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Originally Posted by oldchina View Post
ZeBedie,
According to BAC documentation from that era, the 1-11 water tank was in the pressurised hold so not subject to freezing.
We had to purge the pipes - they'd have frozen!
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Old 6th Mar 2018, 04:02
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I think there was a mod available to have a heater in the water tank on the One Eleven.
The tank was at the front of the aft bag bay just aft of the landing gear cut out and near the skin. I don't think being pressurised means there will be heat around to stop it freezing.
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Old 6th Mar 2018, 13:50
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Originally Posted by chevvron View Post
I was told years ago that every time a Convair 880 took off from Heathrow using water, they had to start taking RVR readings.
It would be good to know which operator of the 880 into Heathrow you are thinking of ...

Originally Posted by oldchina View Post
The Paninternational 1-11 was doomed because it only had one water tank feeding two engines. I suppose if the 1-11 had two tanks the idiot would have still have put kerosene in both, but I thought it a strange design even so.
I don't believe it was whoever filled the tank was an idiot, but the one who, sometime beforehand, who had refilled demin-labelled water barrels with fuel, and then put them back on the line.
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Old 6th Mar 2018, 14:25
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re Pan International

I was part of the HS125 crew that flew BAC personnel from Warton to Munich on 13th September to investigate this accident.
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Old 6th Mar 2018, 15:03
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Originally Posted by WHBM View Post
It would be good to know which operator of the 880 into Heathrow you are thinking of ...
Here's one possibility:



Those were the days ...
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Old 6th Mar 2018, 15:23
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The Gypsy - why did you fly to Munich? The accident happened in Hamburg,I was in Hamburg that night and the Fire engines passed our apartment. It took off over my fathers car as he was leaving the airport and he reckoned the engine noise was incredible.
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Old 6th Mar 2018, 15:42
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We just go where we are told to go by the charterer but assume as the Airline was based in Munich that had something to do with it

I would guess at that time despite taking off from Hamburg nobody would have dreamed that someone at Hamburg had put kerosene in so I suspect they would first of all check maintenance records which were at Munich.
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