Lightning: Avon 30201 Engines

06 Nov 2018 12:36 - 13 Nov 2018 10:03 #40753 by ScottBouch
As installed to the T5 and F6:

| Conditions || RPM Precent || Max JPT DegC || Time limit per flight |
Maximum (with and without reheat)102.579520 minutes combined duration
Intermediate98.077530 minutes
Maximum continuous97.0720Unrestricted
Approach60.0 (Minimum)-Unrestricted
Groud Idling34.0750Unrestricted
Ground Fast Idling58.0 (Minimum)750Unrestricted

100 percent = 8000 RPM

Starting Checks:

10. Idling Speed. Check that engine stabilises at 31 tp 34% RPM and that JPT does not exceed 625degC. Open throttle to 45% RPM and check that the oil pressure failure warning indicator light is out.

13 Two-position nozzle control (non-reheat). Open the throttle slowly from ground idling to maximum RPM and check that the propelling nozzle moves to the closed position at 95% (+/-1%) RPM. Close the throttle slowly and check that the nozzle returns to the open position at 87% (+/- 1%) RPM. (Some hysteresis there)

15 Acceleration (paraphrased) Acceleration times will be decreased by 0.05 seconds for each degree below 15 degC; and increased by 0.05 seconds for each degree above 15 degC.
  • Throttle slam test from 34% to 99% RPM should be 8 to 10 seconds.
  • Throttle slam test from 60% to 99% RPM should be 3 to 5 seconds.


1 - When No1 is not running, No2 may be run without restriction.

2 - Running of No1 Engine when No2 engine is stationary may impose stress upon compressor blading. If it is required to run No1 engine, then No2 engine should also be run at minimum speed of 60% RPM. Only if essential should No1 engine be run by itself; running should be kept to a minimum and the speed must not be permitted to exceed 60% RPM.

3 - When both engines are running and it is required to speed one to maximum RPM, the other engine must be maintained at a minimum of 60% RPM to avoid excessive jet pipe temperature in the slower engine (I think: shared air intake, and no speed = no ram air, the lower speed engine has less air available and will run hotter).

4 - If the ground electrical supply is not connected, and both engines are running, one engine must be maintained at 60% RPM if the other is at Idling, to provide adequate electrical supply to the aircraft services.

5 - Because of wheel braking limitations, 85% RPM must not be exceeded on both engines running at the same time.

Stopping The engines:
Close Throttles ("HP Fuel Cocks"), when the engines have stopped, switch off:
  • Fuel pump switches
  • Fuel cock switches
  • Engine master switch
  • Start isolation switch
  • Battery master switch

Source of everything in this post: AP101B-1005-12 Lightning T. Mk. 5 Aircraft - Ground Handling Notes

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06 Nov 2018 14:06 - 06 Nov 2018 14:07 #40755 by ScottBouch
Throttle image here:

This image shows the engine controls on the throttles:
- Fast Idling stop release lever on No2
- Shutdown lever to go from Ground Idle to stopped, applicable to both No1 and No2 throttles.
The following user(s) said Thank You: Algernon

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06 Nov 2018 14:38 - 06 Nov 2018 14:40 #40757 by Algernon
OK - so I guess either the engine start procedure or taxi/take-off procedure involves moving throttle no. 2 past the stop to the fast idle setting?

In flight, pulling both throttles right back would result in engine no.2 being at 58% (fast idle, against the stop) and engine no.1 at 34% (ground idle)?

If so, does that mean the oil pressure warning light for no.1 engine would come on with throttles right back, as it's RPM would be <%45?

I presume not, so I'm probably missing something! :)

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06 Nov 2018 15:29 - 06 Nov 2018 15:29 #40758 by ScottBouch
Hi, I think you're totally right about the result of pulling right back in flight on the oil light.

There is another factor limiting you pulling No1 back to Ground Idle; human nature - you hold both throttles with the same hand, so you'd have to really want to bring it right down while leaving No2 at Fast Idle.

Once the engines are started (throttles at ground Idle), you'd move one of the throttles to Fast Idle to bring on the aircraft generators, then hand signal to the ground crew to disconnect the GPU (Houchin). I'll check the procedures I have in the aircrew manual, pilots notes and ground handling notes, they should align on this!

Taxiing can be done with one engine at Ground Idle (or even shut down)
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06 Nov 2018 15:32 - 06 Nov 2018 15:33 #40760 by Algernon
Yeah, I would imagine the shape and position of the throttle handles, when held in the palm as intended in flight, would mean you wouldn't naturally bring throttle no.1 right back to ground idle unless you actually intended to. How to handle this in FlightGear, though, taking into account hardware controllers will prove an interesting challenge...

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06 Nov 2018 16:10 - 06 Nov 2018 16:10 #40765 by ScottBouch
I'd been thinking about this...

You could range the desk throttle from 0 to 100% to match with the simulator throttle, but then latch the aircraft throttle at Fast Idle when coming down, using a keyboard button to get past this latch to Ground Idle?

Or ignore the Fast Idle latch and let people's monitor the %RPM gauges... May be easiest?

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06 Nov 2018 16:23 #40769 by Algernon
I had already pretty much decided to simulate the latch in the way you describe - this is how I've done the engine shutdown gate lever (HP cocks) on the Victor.

I think it might be a decent workaround to apply that latch to both throttles in the code, but still only have one release button on the 3D throttle. I'm certain 99.9% of pilots wont notice the difference, however they might notice the difference if every time they throttle right back they get an oil pressure warning... in an aircraft with the Lightning's reputation, it might be cause for significant concern!! ;)

To be honest, what I really need to do is write us a new bit of engine management nasal - the existing code is a bit elderly and generic - which accurately models LP and HP fuel cocks and would allow for quirks like this one, present on many aircraft of the period we like to model and fly. I'd definitely like to have the HP cocks modelled into the throttle assembly, as I think this is pretty universal and would allow shutdown from hardware throttles in a realistic fashion.

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06 Nov 2018 16:40 #40772 by ScottBouch
Hi bud,

If you do re-model this script, can I ask for one addition; the ability to enable or disable the likes of these keyboard buttons and software latches..?

Reason I ask is that if the model is to be used with real hardware, ie: a real set of Lightning Throttles that I'm angling after, I'd have the hardware physically doing this function, and having to press the keyboard would be a pain in this instance.

Basically, giving you the choice of using the model with generic shop bought controllers and keyboard buttons, or real or custom made hardware where the keyboard is not needed. Could be enabled / disabled by having a property in the property tree to set to true or false depending on the sim hardware configuration.

Another feature like this is steering the Lightning... with real hardware you'd do this with a potentiometer on the stick for variable braking, then bias this left and right with the rudder pedals. Some people will have USB pedals, but no stick brake lever and wish to steer with their toe brakes, some people will use 0 and Enter buttons on the keyboard. I intend on doing it as per the aircraft. It'd be ace to be able to configure the Lightning for the hardware in this way by selecting properties to suit.

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06 Nov 2018 16:59 #40776 by Algernon
Funnily enough, I was thinking about ground steering while I was taxiing her today. I hope to get this working realistically pretty soon, but I suspect I'll be modelling the hydraulic system reasonably accurately (though simply) so it's probably a job for after that.

Either way, don't worry about the control mechanisms - they are just bindings, and where there is a keyboard shortcut to operate anything you can also just add an additional binding to your hardware config XML which does the same thing. Adding an enable/disable is probably not necessary, and could be problematic in some circumstances, not to mention it adds a considerable layer of extra complexity which is definitely not desirable for controls.

Specifically regarding steering, though, it will need to be thought about. Some people will grumble and criticise the aircraft if they can't just (cheatingly) nosewheel steer it with whatever controls are bound to the rudder. I prefer to have nosewheel steering on a potentiometer on my hardware when it's a separate control (and I think it often is on real aircraft, particularly Cold War era ones like the Victor) and here a property tree node to switch between real or convenient configs would be desirable.

Obviously, the variable brake steering on the Lightning is a special case. Please see new thread .

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13 Nov 2018 10:07 #40884 by ScottBouch

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