Nimrod, and RR Spey ...

[Terrorfex]

I've been pointed this way by some fellows over at E-Goat.

Would anyone happen to have the take-off speed of the Nimrod handy? A figure of between 122 - 135 kts has been bandied about.

More unlikely still, does anyone have an inkling for the diameter of the Rolls Royce Spey powering the Nimrod? I've been able to find a Jet Pipe diameter of .99 metres, but can't find anything regarding the intake.

Any assistance goes directly to making my number-crunching coursework that bit more accurate.

Cheers.

[kevnurse]

At 120,000lbs AUW, VR was 111 kts,
At 130,000lbs AUW, VR was 117 kts
At 184,000 lbs AUW (normal max permitted), VR was 142 Kts

Diameter of a RR Spey engine air intake at the engine is approx 1 metre; probably approx 1.5 metres at the wing leading edge, but I'm guessing from memory.

"AUW" is the total weight of the aircraft and everything on board.
"VR" is the speed at which the pilot pulls the column rearwards to get airborne.

Good luck with your course work

Regards
Kev

[Terrorfex]

Kev, that's of great help; especially the weights.

I've done a little more research and found a slightly more accurate assessment of the exhaust (jet pipe) diameter as being 0.83 metres. The ratio between inlet and exhaust seems a little small to me, but then again most of my previous calculations have been with newer engines.

[Fox3WheresMyBanana]

I remember the Nimrod/Spey coming up on my jet engine design finals paper in 1984!

[Terrorfex]

We were free to pick any aircraft and engine combination. Virtually everyone is going with something safe, like a commercial airliner and associated engine e.g. CF6. I almost went for the Phantom myself, but the addition of the afterburner made it a little too complicated for the time I've got left to number crunch!

[Herc-u-lease]

Spey - Rolls-Royce (http://www.rolls-royce.com/defence/products/combat_jets/spey.jsp)

I assume you found this already? Have you considered dropping Rolls an email asking? If you don't ask you don't get.

H

[pmills575]

If you are unable to find info via t'internet etc, we at Gatwick Aviation Museum have an ex Nimrod Spey amongst our engine collection. So I could be persuaded to measure the beast if required.

pm575

[Fareastdriver]

"VR" is the speed at which the pilot pulls the column rearwards to get airborne.

VR is not the take off speed. VR can be called up to 25knots before the actual takeoff speed.

[Gulfstreamaviator]

VR is the rotation speed, ie at which speed a Pilot yanks the sticky thingi back, and hopes that beasti will get airborne.
So as mentioned actual take off speed is in excess of that number, and depending on several variable thingies could be very close or some distance away from that point.

sorry to be so technical.

gulfi

[Roland Pulfrew]

VR is not the take off speed. VR can be called up to 25knots before the actual takeoff speed.

So as mentioned actual take off speed is in excess of that number, and depending on several variable thingies could be very close or some distance away from that point.


To be very picky,:E the Nimrod did not have a calculated "take-off speed", only V1, VR and V2, so as Kev pointed out the the closest to the question asked is VR. A "take-off speed" for the Nimrod would be somewhere between VR and V2 and (without access to the relevant docs) I think that would be no more than 10 or 15 knots above VR - but I am sure Kev will be able to provide more info!:}

[thunderbird7]

Surely no thread about the nimrod and the Spey cannot be complete without:

"ninety-four-and-a-half-five-ten"

:)

[Duncan D'Sorderlee]

98/560

Duncs:ok:

[ShortFatOne]

Button, air valve, rotation.......

[Terrorfex]

EDIT: Good old fashioned grunt work found a solution to the fuel flow quandry.

Appreciate all the help offered so far, though.

[OpsLoad8]

Or more likely, button, no air valve!

[QTRZulu]

Or for those of us with memories that go back a little further -

'Routine engine shutdown for fuel economy'

Now those where the days!

[Eminence Gris]

Spey fan diameter is 32 inches.

EG

[thunderbird7]

Bloody hell! This sounds like a GSU grilling thread! Now draw the fuel system... :}

[Party Animal]

and the number of holes in the airbrakes was?

and if anyone gets that right, what diameter was the holes?? :)

[Sandy Parts]

A-cat question - activation weight of the spring-loaded flap in the toilet?..

[MKIII]

37 holes in each airbrake paddle; 21 big ones and 16 little ones.

[thunderbird7]

116 sq feet...

[Fox3WheresMyBanana]

Here we go again:

How many bits of wood in the JP?

What's the current in the secondary coil of the E-I bar of the ILS localiser?

All those hours sitting there learning such rubbish.
It had one benefit - when I became a teacher myself I knew exactly what not to do.

Such a pity really, since there was so much additional useful non-syllabus stuff which could have been done with the time.

Some GI's were great. I remember doing double-difference techniques for when the graph didn't reach your location for working out the take-off roll of the JP. When you used it, the T/O roll worked out at 2,000' for every RAF airfield. Why bother?, one thought. Then 9 years later I was flying a civvy JP and had to divert into Window Rock, Elvn 6,742'. And do you know what? It bloody works you know. Thanks Wacky!

[Shaggy Sheep Driver]

Spey fan diameter is 32 inches.

32"? That's not a fan, that's a compressor stage!

What was the max boiler pressure of a Robert Stephenson 'Planet' locomotive, and why does the modern replica run twice that pressure? :E

[FE Hoppy]

cross shaft bridge casting.

end of thread!

[Ivan Rogov]

Large airbrake hole diameter was slightly more than a can of beer :ok:

List 3 ways to stop the multi crew sim on demand? :E

[AA48]

No need to stop it. Just step quietly out the front door?

[Surplus]

Dividers across the Jez light.

Big red button.

Lose the sub during a GSU ride.

[Old Fella]

Earlier posts made mention of "Take-off" Speed and it was correctly noted that the speeds which are of importance are in order: V1 which is the minimum speed at which the take-off may be safely completed in the event of an engine failure. V1 will always be higher than Vmcg (minimum conrol ground) and it is also the speed, which when reached, an attempted aborted take-off will almost certainly result in an over-run of the remaining runway.

Vr is the speed at which the nose of the aircraft is raised, or rotated, to the flying attitude and enables the aircraft to become airborne. Rotating too early will lengthen the take-off roll and likely result in a tail scrape on many aircraft.

V2 is the speed at which, having become airborne, the aircraft will be controllable and achieve the minimum climb gradient in the event of an engine failure. V2 is always higher than Vmca (minimum control speed airborne) So "Take-off" or "Unstick" speed will always be greater than Vr and less than V2. Climbing at V2 + 10 KIAS will give better climb gradient performance than V2.

[Ivan Rogov]

I should have been more specific, 3 ways of making the MCT pain end for the day without getting in the dwang :}

All this talk of take-off speeds was academic for a rod in the gulf, we relied on the curvature of the earth to get airborne. The pilots self preservation and one would chicken out and pull back (a bit more when it was hot ISTR) before we ran out of runway, unless they were having something delivered :eek:

[Sideshow Bob]

we relied on the curvature of the earth to get airborne
The happy memories of WAT limit take-offs from Seeb. Brings a tear to the eye :}

[camelspyyder]

Was Basra not worse mate - it was certainly hotter, we had a 5 degree C extension to the limiting operating temperatures there.

Oh and you could kill the MCT by coupling it to the DS, causing the nav system in the tube to jump to the DS position ( 0000N/S 00000E/W most of the time since it was off)

Since it didn't revert on uncoupling no-one ever knew:)

type C/Y/enter C/N/enter CLEARSCREEN and 10 minutes later we're all in the Mess Bar

CS

[Ray Dahvectac]

activation weight of the spring-loaded flap in the toilet?..

7lbs IIRC. :ooh:

[Sideshow Bob]

Was Basra not worse mate

I think they all had their own charm, Seeb with the high ground to south, Thumrait with it's 1500' elevation but yes, the fact you wanted to be below 3 grand for as little time as possible made Basra a bitch (which bring you nicely to the argument of whether to go low pick up speed then climb fast or to climb at V2+5).

The worst of the lot though was bringing Tristars out of Kabul way overweight iaw perf A knowing your only option on engine failure after V1 was to head for the nearest valley and hope it eventually climbed.

[OpsLoad8]

7lbs - more than three bags of sugar!! 7 oz possibly!!