Tornado Reheat Question

[speedrestriction]

Hello folks,

A pair of tornados took off ahead of us today at GLA rwy 05. Both used reheat. Is this required with such a long runway? The noise was fantastic.

sr

[ZH875]

reheat is not needed......




....But it would be a :mad: long taxi back to their homebase.

[soddim]

Aah - jet noise, the sound of freedom heard at GLA.

The cold power departure requires a curved earth and a runway so long that the mag var would vary during take-off!

[Air Defender]

You probably could get airborne without reheat, if you could garentee no engine failure, but it would be a massively gutsy move and the take off roll would be massive.:eek:
If you watched them they will have run the engines up to max dry then lit the burners one at a time and allowed them to stabilise once lit before releasing the brakes. They take a finite amount of time to light up and start producing thrust and they don't always light.:eek:
Both of these would pose an unacceptably high risk if the take off was carried out without both burners already lit at the beginning of the take off roll.

[Impiger]

Had a stude on the F4 OCU take off in cold power (ie no reheat) - then he was a Jaguar pilot we were cross-training and his excuse was that the acceleration was better than he was used to so he thought it would be OK.:D

[BEagle]

At least it probably made a change from cross-dressing?

"Don't bend down..........."

[flipflopman RB199]

They take a finite amount of time to light up and start producing thrust and they don't always light.


And that usually signifies that it's time for the Landrover speedo cable, to take a little trip through the Hot Shot injector again!! :p


Flipflopman

[Air Defender]

Impiger, I know that student he taught me. When he tells that story it is very amusing.:ok:

[gashman]

Using the 'burners gets you to your decision speeds faster and with more runway ahead of you so you can still stay on the ground if (when) you suffer a reasonably serious snag without much drama.

[peppermint_jam]

"And that usually signifies that it's time for the Landrover speedo cable, to take a little trip through the Hot Shot injector again!! :p"

lol, there's some memories!

Best purging tool the RAF never bought IMHO!!!

[Zoom]

The RAF F-4 had enough problems with its engines but at least you could light both burners simultaneously (although taking about 3 seconds) and expect them to work. And you would have to stamp pretty hard on the brakes to stop the machine from moving in full a/b; in fact, I'm not sure if you could stop it moving. But this problem with the Tornado, does it apply to all models?

[soddim]

It's not a problem. Both throttles can be slammed idle to max reheat for operational use and it is rare that anything abnormal occurs; however, the probability of engine surge or reheat failure is reduced by handling the light-up in a more controlled way and this makes sense for normal training use.

[flipflopman RB199]

As Soddim says, certainly not a 'problem' as such.

Failure to light does occur occasionally, but is more likely than not a quick fix, and usually does tend to be a dirty Hot Shot injector. This is rectified either using a bastardised Landrover speedo cable which is passed through the fuel feed pipe from the ABFCU to the Hot Shot head, to remove the offending carbon. :ok:

The alternative 'correct' way, is to use the R-R Hot Shot purge tool. This is a 12" stainless pipe, which connects to the Hot Shot injector itself and is pointed to atmosphere through the open engine door. An EGR is then carried out, which reverse purges the head of the injector. Obviously this is a little more time consuming, but the officially favoured way :p

As an aside, Reheat lights are usually pretty instantaneous, and can definitely be felt as a light 'thump' commensurate with indication of light up on the Aj gauge.


Flipflopman

[Air Defender]

Don't know I never tried to hold it on the brakes in Max Reheat but I know a man who started a take off roll in the Falklands on a slushy runway with the parking brake on. The unusual D shaped wheels now adorn the Goose. Strangely he didn't get airborne off that attempt.

[flipflopman RB199]

Can confirm that Air Defender.

I was on 1435 at the time, and also the MC of the Eyrie Bar. I was 'Handed' the CVR tapes, which made for an amusing evening in the bar that night!

As I recall the parking brake was applied due to the VC10 taking it's time backtracking along the runway. Indeed, the chat between the Pilot and Nav prior to the incident, was about the Tenerife air disaster and what a cock up it was!! :p :E


Flipflopman

[Air Defender]

Oh how we laughed when he tried to prevent the story getting back to the UK.

Light up might be immediate but the production of significant extra thrust isn't, a few seconds of extra stress in the event of one of RR's finest Sh*tting the bed.
Certainly when tanking, and more oomph is required, light one burner then wait a few bananas for the thrust to come before retarding the donk left in dry. Pull the other back too soon and you fall out, too late and the tanker appears very large in front of you.

[L Peacock]

....or sometimes tweak the WLLTDB Flip-Flop:ok:

[speedrestriction]

If you watched them they will have run the engines up to max dry then lit the burners one at a time and allowed them to stabilise once lit before releasing the brakes.

Yep, thats exactly what they did. Thanks for the answers.

sr

[flipflopman RB199]

....or sometimes tweak the WLLTDB Flip-Flop

L Peacock,

As I'm sure you are fully aware, the WLLDTB or Working Line Limiter Datum Test Box (rather than WLLTDB) Is there to ensure that regardless of the PLA (Pilots Lever Angle) the engines will produce Dry Thrust only, and not open the nozzles in anticipation of Reheat, therefore risking LP Turbine overspeed. 70% Aj, as I remember. :ok: :ok:

Seriously though, it was usually Hot shot trouble, or Reheat FCU trouble that resulted in No Light Up. I'm also sure however that the Phantom also had it's own little quirks, it's just that I'm far too young to remember!! :p


Flipflopman

[flipflopman RB199]

Air Defender,

As I remember, he did all in his power to prevent us from playing the CVR tape too. As I remember, it was the Nav who noticed at 110kts, that the aircraft appeared to be 'skidding'

Accompanied by a very swift "Oh F**k"

:E


Flipflopman

[L Peacock]

flip flop

yep agree, it's usually hot shot.

i'm sure you remember (it was a long time ago for me as well) that WLLTDB stands for Working Line Limiter Trim Datum Bias. ;)

[flipflopman RB199]

L Peacock,

For once, I stand corrected with on my RB199 knowledge!!:eek:

It is indeed Trim Datum Bias. I applaud your memory of such mundane TLA's!!

I did actually have to go and break open my Cottesmore Tornado School Notes then!! And in honesty was confronted with page after page of "Lowest Fuel Wins" notes that I'd hoped to forget years ago!!

I'll trade you your "Trim Datum Bias" tweaks for a good old Hot Shot clean though!!

Regards,


Flipflopman

[Jobza Guddun]

Air Defender,

As I remember, he did all in his power to prevent us from playing the CVR tape too. As I remember, it was the Nav who noticed at 110kts, that the aircraft appeared to be 'skidding'

Accompanied by a very swift "Oh F**k"

ISTR a similar event happening at Coningsby in the early 90's. The remains of the mainwheels and brake units were most impressive.

Bad luck for the team whose post-minor air test it was though.....

[flipflopman RB199]

And also LP,

Tweaking the WLL, wouldn't help you relight the Burners. It'd just set a slightly different Aj for the DECU/MECU to take control and stop the Burners from lighting up


Flipflopman

[XL391]

Cutting through all the bull sheisen, are Tornado engines weedy? :}

[L Peacock]

Flop Flip
You're right, it's often the hot shot, i've already agreed. But, more than once, I've come across the WLL locking a burner out, though on reflection it was down to a dodgy turbine diff px tranducer or completely wrong MECU setup on intallation runs.

and XL391, yes a bit weedy in dry power.

[Sheep fancier]

Is this you, and them ----

http://www.saap.co.uk/Tornado-2.wmv

SF

[engoal]

Casting my mind back to a classroom at the RR Filton factory, I distinctly remember an ex-Shack Air Eng called Len Schofield telling us about the fluidic flip flop valve (Turbine Pressure Ratio Transducer) that compared pressure either side of the LP turbine and ensured that the RHFCU would stop delivering fuel if the ratio got too high or too low. There is even an urban myth that it was intended to form part of the active feedback loop for fuel control in reheat, such that nozzle opens, fuel flow increases, TPRT detects change in pressure ratio, fuel is trimmed accordingly.

It was also a useful tool for fixing a sticky nozzle in the days of vactric motors. Having waggled taxy nozzle a few times, you got the pilot to drop the offending engine into ENC (which often took some explaining), disconnected the RHFCU fuel solenoid, got the slightly concerned pilot to reset the ENC and 'exercise the throttles up to max reheat', explaining that it couldn't light but would 'blow out' because of the TPRT and drop to the normal dry nozzle area. After returning the nozzle to ENC, simply reconnect the RHFCU solenoid, step smartly away to the side of the aircraft and invite the pilot to try again - 8 times out of 10 this would result in heat, flames, noise and a happy pilot :ok: , occasionally followed by a scowl from the SEngO for conducting reheat runs on the pan! Oh the happy days of TWCU.

[Air Defender]

XL391 Yes a wee bit on the weedy side. But then again if you ask any pilot of any aircraft what you could do to improve the aircraft that he flies the number one response is "Give it Bigger Engines"

Number Two is "Give it a Bigger Wing"

So nobody is ever happy.
Give me 50,000 KN Thrust I'd want 60,000KN Obviously!:E

[luffers79]

Historical Reminder.
The Swift FR5, which we flew in Germany in the 50´s, was the First R.A.F. aircraft to be equipped with reheat. (R.R Avon114, approximately 7000 lbs Dry, 9,500 Wet- BUT... Only about 4000lbs if the reheat failed & the eyelids were not yet in the Dry position. I seem to remember they took about 4 long seconds to revert & regain Dry thrust). As we operated frequently off 2000 yard runways Wet, with not a lot to spare - especially on a calm hot summers day, reheat failure was not a thought to dwell on. There were no crash barriers in my time. Fortunately we were lucky not to have such an incident.
Anyone else out there remember those days ?? (PM always appreciated!!).

[False Capture]

Air Defender,if you ask any pilot of any aircraft what you could do to improve the aircraft that he flies the number one response is "Give it Bigger Engines"I completely agree. The engines on my B777-200 only push out 93 400lbs of thrust. I want those big babies fitted to the -300s which push-out 115 000lbs of thrust per engine.:ok:

[Air Defender]

False Capture,

If the Tornado had that much thrust it would be a pleasure but to return to the begining of the thread it wouldn't sound nearly so good and it wouldn't look so good getting airborne at dusk! Carrot power is the way ahead, the choice of champions and it reminds people how quiet the airliners actually are.

[advocatusDIABOLI]

'Are Tornado Engines Weedy?'

Not when you consider they are only slightly bigger (physically) than a packet of Rolos! Weedy or Efficient? I aggree tho, more thrust is always better.....:E

Advo

[speedrestriction]

Sheep fancier,

Yep

[CJS]

Sheep Fancier.

It's them...

... and me. I was in the back of the second GR4 (callsign Midas 2), having just spent a very enjoyable evening with UGSAS taking part in a Tornado capabilities brief for the students, ably given by the crew in the first GR4 (Midas 1) that took off about 5 minutes before. See also the thread on the UGSAS reunion.

In answer to Speed Restrictions question, we could have got airborne without the reheat, but for (most of) the reasons already given, and to improve the safety margin had it failed, we used it. Besides, if you had it, it would be rude not to use it. Makes you guys sound positively quiet to.

SR. Hope you had a good trip but I bet it wasnt as much fun as the one we had on the way back to Lossie.

To OC UGSAS all the staff and students we met on the Thursday night, thanks for a great time. To Midas 1, thanks for organising a great night out.

CJS

[advocatusDIABOLI]

CJS- 'We could have got airborne without reheat'- Really? Using what ODM data would that be?

Silly Boy :=

Tonkas Take off WITH Blower, Always.

Advo

[Air Defender]

CJS I guess I'll see you through a haze of beer at the UGSAS re-union then.:ok:

[CJS]

Advo.

Before you go wagging your fingers around and slagging people off I wonder if you have checked out the video. If so, you would have seen that the jets we were in were clean (and it was also pretty cold on Friday morning) and whilst I agree that Tornado take offs are always with reheat (for all the reasons discussed), I believe we probably could have got airborne without it.

However, the reason for me posting the thread was not to invoke a discussion on the merits of the ODM or the servicability of the Tornado reheat and whether it can or can't get airborne on 9000+ feet of runway. It was to pass on my thanks to the people at UGSAS who hosted us so well and to the junior crew who organised the night out and who gave an excellent presentation.

Negative comments and finger gestures directed towards people who are trying to use PPRuNe in a positive way is what gives this site such a bad reputation. Next time why not email the person directly or alternatively, keep your comments to yourself.

CJS

[advocatusDIABOLI]

CJS,

Whilst I aggree, that positive use of pprune to say a heartfelt 'Thanks' is laudable, the facts remain. Even on a 9k runway, on a cold day a Tonka taking off in 'Dry Power' would be both foolhardy and dodgy at best. (Clean or otherwise- By the way you had outboard stores).

In my view, stating that it 'could' have been done or even voicing the consideration on this forum was ill advised; It couldn't, and it shouldn't.

I do however appologise for the finger waving, that really was uncalled for. Glad you had a nice evening.

Advo

[AI24]

Seem to remember the Buccaneer getting airborne at 50000lb's AUW with a pair of 11000lb thrust Speys without any problem? And without the high lift devices of the Tonka? Interesting to know what would have happened though if you did lose one late on down the runway.:eek:

[advocatusDIABOLI]

OK, my final (you'll be all pleased to hear!) word. A Tornado F3, in 'Light Combat' Fit at Max Reheat takes about 3000-3500 Ft to get to Unstick. Since Max Dry power is broadly half of max reheat, we can assume that the roll would be about twice as long, ie. 7000Ft. So, It would be possible to take off on a 9000Ft runway in dry power, but, and it's a BIG but, your take off safety margins in the event of a rejected take off would be non existant! One shot deal, any problems and you've had it. You wouldn't even to be able to take the overrun cable! (Too Fast for weight).

So, although theoretically 'possible'....... 'actually' very stupid. In a similar way, it is 'possible' to walk slowly accross the M1 blindfolded.

Please feel free to use any technique you like, but for me it's 2 good burners or nothing.

Regards to All,

Advo :)

[threeputt]

It's somewhat imotive. I remember seeing a situation when, at Bruggen, a IX Sqn GR1, operating from the southern taxiway, get's airborne but, looses a burner; "lummy days" he put the bloody thing back down on the ground and engages the RHAG!! Worst bit of adhering to the pre-take off brief I ever saw in all my life. They know who they were!:mad:

3P.

[cornish-stormrider]

that must have been fun.

I was in akrotiri with 11 and we had a hlwscu failure and jammed the waggly wings at 45 degrees. fast landing, I believe the grobag broke the wheelbrakes and so used his nuts to stop the rot.

[jonesthepilot]

Can't remember the exact numbers but believe the ooomph in full burner is about 60% greater than max dry. Who was it that coined the phrase(corny)'See those needles swing, feel those babies bite' Yuk!!:hmm:

[bowly]

3P - Not me!

[mojocvh]

Nice panorama of the Kilpatrick Hills in the video, quite a few WW2 cabs still up there (in pieces)
It doesnt matter about dry/reheat T/O if the wings are still swept!!! as some of the girlschool so nearly found out once......:ouch:

[L Peacock]

jonesthepilot

It's closer to say max dry thrust is about 60% of max reheat.

[BEagle]

1.67 x f*ck all is still f*ck all! Just noisier.

[advocatusDIABOLI]

Beagle, what a pity.... you usually speak sense and reality.

Advo

[BEagle]

Banter, me old, nothing more....

Is that still allowed in today's grey PC world?

[just another jocky]

As a mere aside...

I did 3 years at Cottesmore on TTTE where we flew exclusively clean aircraft (not even pylons) and despite having only the 101 engines fitted which had less reheat thrust but the same dry power (I think ???) I always wondered whether we could take-off in dry power and if anyone had ever worked out the figures. It certainly felt like you could.

I do understand the banter about weedy thrust, but I did once have a genuine 590kts in dry power at low level out of a GR1, and that wasn't at the end of a dive or anything, just low level RTB from Donna Nook and forgot I'd left them at Max Dry. :ok:

[DSAA]

"Banter, me old, nothing more....

Is that still allowed in today's grey PC world?"


You can't call it that...it's a paler shade of charcoal!

[flipflopman RB199]

just another jocky,

You were doing well indeed to squeeze that from a TTTE jet with 101's! :D

As I remember, the 101's only had something like 8000lbs thrust in Dry range, whereas the 103's had around 9600lbs eventually, post the 8% compressor mods.

Good work fella!! :ok:


Flipflopman

[BackfromIraq]

Surely the old saying:

"The three most useless things in flying are height above you, runway behind you and one second ago"

still count?

I've never had the inclination to find out whether anything can take off on less than max power.

"There are old pilots and there are bold pilots, but there are very few old bold pilots."

:hmm:

[Brain Potter]

I've never had the inclination to find out whether anything can take off on less than max power.

Nine out of ten take-off runs you've every experienced on an airliner will have been with much less than maximum thrust. But I guess there are no derate figures for FJs :}

[L Peacock]

Combat, bleed off or max reheat, bleed on are both approved techniques.

[flipflopman RB199]

Combat, bleed off or max reheat, bleed on are both approved techniques.

With respect LP, those are not really in the same order as a rated take off, and are not in theirselves classed as a 'derate' figure for the Tornado

Tornado's nearest to a rated take off must be a 'Low' selected datum with ECS selected 'ON'

Even this though, as I'm sure you'll agree, is in a different league to a 744 EPR 'Rated' take off.

Flipflopman

[L Peacock]

flip flop

It was just a point of interest really.
BTW, I'm told the datum switch stays in the low position these days.

[advocatusDIABOLI]

LP, you are right. The 'Carlos Fandango' (Datum) switch stays firmly wirelocked in Low. The reason for this, is that after certain 'modifications', selection of High would give the F3 an unacceptable power advantage over the Typhoon.

Now we wouldn't want that, would we? :E

Advo

PS- 101 Dry - 8400lb 103 (With 106 Compressor) Dry - 9400lb. Max RH (ISA Sea level) 17,600lb.

[cornish-stormrider]

wasn't the decu datum switch set to give an extra XX degrees of temp in the combustion chamber?? and then didn't putting the PLA to combat give another XX on top?? Didn't know if the figures were not for public display or not. I do remember when we redatumed all the decus on 11sqn the first 4 ship of monday morning took off with comments of sporty jets etc and came back to 4 sets of double boro's front to back. My mate Billy wasn't a happy sootie.

[flipflopman RB199]

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

[cornish-stormrider]

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.

[spearheadxxx]

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!:ok:

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!

[flipflopman RB199]

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 :sad:

As an aside, digging out the '199 course notes gives 24 Deg C for both the Datum Low selection and Combat.

Cheers


Flipflopman

[cornish-stormrider]

Spearheadxxx.

So it was you wot done the dreadful deed:E.

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

[engoal]

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).

[cornish-stormrider]

I never said I was current but all of these figures seem about right to me. I was just a humble mushroom though

[flipflopman RB199]

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 :8

How utterly, utterly sad am I?!?


Flipflopman

[cornish-stormrider]

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

[Flap62]

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.

[cornish-stormrider]

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:E:E