Tornado Reheat Question
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It did indeed cornish-stormrider,
Initially, the datum/low switch was designed to be left in 'datum' doing just what it said on the tin, however, over time, it was discovered to extend the engine life considerably if selected to 'low' which, as you say, dropped the max TBT by around 25 deg C. As you say, a combat selection raises it by roughly the same amount, for a slight power boost. I remember that when we were operating a mix of 101 and 103 engined GR1's though, that the 101's were always operated at 'Datum' whereas the 103's would be wirelocked to 'low'.
IIRC, when tweaking the DECU/MECU TBT pot, 25 deg C was also the amount necessary to raise or lower the NH by 1%.
Flipflopman
Initially, the datum/low switch was designed to be left in 'datum' doing just what it said on the tin, however, over time, it was discovered to extend the engine life considerably if selected to 'low' which, as you say, dropped the max TBT by around 25 deg C. As you say, a combat selection raises it by roughly the same amount, for a slight power boost. I remember that when we were operating a mix of 101 and 103 engined GR1's though, that the 101's were always operated at 'Datum' whereas the 103's would be wirelocked to 'low'.
IIRC, when tweaking the DECU/MECU TBT pot, 25 deg C was also the amount necessary to raise or lower the NH by 1%.
Flipflopman
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Flip-Flop, I've got the figures 34 for the decu and 26 for combat rattling around in me noggin. How sad am I??
I'll never forget when Leuchars TPF rolled up to Lossie with a 104 that was having surge problems and blew the doors off the UETF and lifted the roof six inches. The whole side of the bay rolled in like it was in the matrix and the fire engine launched out of its garage, straight across the airfield and bogged down off the side of the runway! IIRC the guy running the engine was doing it from under the desk. He said he knew it would go bang and it was just a question of when.
Or an SAC of my aquaintance forgot to fit the 8 rcat to HPT bolts - one scrap 199 that I had the pleasure of taking apart with a hammer & chisel. And he got his fitters course.
I'll never forget when Leuchars TPF rolled up to Lossie with a 104 that was having surge problems and blew the doors off the UETF and lifted the roof six inches. The whole side of the bay rolled in like it was in the matrix and the fire engine launched out of its garage, straight across the airfield and bogged down off the side of the runway! IIRC the guy running the engine was doing it from under the desk. He said he knew it would go bang and it was just a question of when.
Or an SAC of my aquaintance forgot to fit the 8 rcat to HPT bolts - one scrap 199 that I had the pleasure of taking apart with a hammer & chisel. And he got his fitters course.
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Cornish-stormrider,
You are nearly correct, 36 degrees for the datum switch and 24 degrees for the selection of combat.
I have to own up to being the "brave" chap from Leuchars UETF that trashed your test bed. In fact two days previously I had trashed our own test bed in much the same way! Eventually turned out to be the RHFCU at fault, or more accurately the turndown actuator. Hell of an expensive way to find out though eh?
Three of us travelled north from Fife to meet the engine and there was standing room only in the running cabin...the three of us and most of Lossie's test bed crew. All was going well and we were describing the fault and how it happened to the local team, when I uttered the unforgettable words " and just about now it might go b.......ANG!!!!!"
Cue lights and paint falling from the ceiling, squeals from the Lossie boys and lots of nervous chuckles! Underwear checked...satis, honour satisfied!
The Leuchars UETF was out of action for several weeks and the repairs cost an estimated £60,000. I'm not sure Mr Brand ever forgave me for trashing his UETF!
Happy days!
You are nearly correct, 36 degrees for the datum switch and 24 degrees for the selection of combat.
I have to own up to being the "brave" chap from Leuchars UETF that trashed your test bed. In fact two days previously I had trashed our own test bed in much the same way! Eventually turned out to be the RHFCU at fault, or more accurately the turndown actuator. Hell of an expensive way to find out though eh?
Three of us travelled north from Fife to meet the engine and there was standing room only in the running cabin...the three of us and most of Lossie's test bed crew. All was going well and we were describing the fault and how it happened to the local team, when I uttered the unforgettable words " and just about now it might go b.......ANG!!!!!"
Cue lights and paint falling from the ceiling, squeals from the Lossie boys and lots of nervous chuckles! Underwear checked...satis, honour satisfied!
The Leuchars UETF was out of action for several weeks and the repairs cost an estimated £60,000. I'm not sure Mr Brand ever forgave me for trashing his UETF!
Happy days!
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Spearheadxxx,
Not really a story I'd be too proud of telling mate, two test beds trashed all for the sake of a dodgy turndown actuator
As an aside, digging out the '199 course notes gives 24 Deg C for both the Datum Low selection and Combat.
Cheers
Flipflopman
Not really a story I'd be too proud of telling mate, two test beds trashed all for the sake of a dodgy turndown actuator
As an aside, digging out the '199 course notes gives 24 Deg C for both the Datum Low selection and Combat.
Cheers
Flipflopman
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Spearheadxxx.
So it was you wot done the dreadful deed
.
There were pants, kittens and liquid adrenalin all over the bay!!!.
Our M15 bay had an idea for using a module 15 in robot wars. They reckoned if we put an air tank in the pipe and fitted it with wheels they could use the buckets as the primary weapon.........
Zer Kaipitain said no, zer iz night enough zervicable donken das ist ein zervice.
OC lossie TPF was a german exchange post
So it was you wot done the dreadful deed
.There were pants, kittens and liquid adrenalin all over the bay!!!.
Our M15 bay had an idea for using a module 15 in robot wars. They reckoned if we put an air tank in the pipe and fitted it with wheels they could use the buckets as the primary weapon.........
Zer Kaipitain said no, zer iz night enough zervicable donken das ist ein zervice.
OC lossie TPF was a german exchange post
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Standing by for ridicule as ex-sooty reveals 11-year currency gap!
TBT Datum switch gives 36deg TBT change, while selection of combat gives you +15deg (Mk 101s) or +23deg (Mk 103/104s).
TBT Datum switch gives 36deg TBT change, while selection of combat gives you +15deg (Mk 101s) or +23deg (Mk 103/104s).
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As I said, I was a little surprised myself as I too thought that the 'Low' selection trimmed back more in the region of 30 Deg C, but having dug the RR RB199 course notes out, under 'Dry Engine Control (GR1-MECU)' it gives a temperature change of 24 Deg C for both 'Combat' and 'Low' selection which is governed by the TBT datum signal versus 'Actual TBT' passing through error units, with the 'Lowest Fuel Wins' signal acting upon the LPC solenoid to reduce engine fuel flow 
How utterly, utterly sad am I?!?
Flipflopman
How utterly, utterly sad am I?!?
Flipflopman
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I have vauge recollections of part of that, I did spend the entirity of gas turbs at Cosford out of my brain on high end painkillers. I passed with a 96% and my instructors tell me I didn't cheat.
Lowest fuel wins ZZZZZZZZZZZZZZZZZZZZZZ
Lowest fuel wins ZZZZZZZZZZZZZZZZZZZZZZ
Mods,
From what started out as a reasonably interesting ops related thread, it has now meandered somewhat. Any chance it could be moved into either the "techies" forum or failing that the "I really ought to get out more and stop boring everyone with pointless trivia" forum.
From what started out as a reasonably interesting ops related thread, it has now meandered somewhat. Any chance it could be moved into either the "techies" forum or failing that the "I really ought to get out more and stop boring everyone with pointless trivia" forum.
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I do Sooooooooooooo humbly apologise on behalf of us nerds and techies, Just remember it takes all sorts and most of our greatest inventors and innovators are nerds!!!
Be nice or there won't be any more shiny shiny toys for you
Be nice or there won't be any more shiny shiny toys for you
Last edited by cornish-stormrider; 30th May 2007 at 13:23. Reason: carp seppling
