Flameouts, compressor stalls, fires…… F-14A was not an easy plane to fly and Aerosoft’s add-on may shock less experienced sim pilots. Let’s break it!
Test #1 flameout
I will start with a simple test. The engine quits. Every driver experienced it but it is an entirely different experience at Mach 1.4. What happened?
The F-14 was flying at low altitude and the throttle was pushed forward – full afterburner. With it’s wings swept back at 68 degrees Tomcat was accelerating. Mach 1.1, then 1.25 and finally it reached Mach 1.4. It’s above the maximum Mach number for this altitude. Suddenly – both engines quit. Just like that.
That is a flameout of a jet engine.
What happened? There was not enough fuel… or air… or heat
The jet engine needs three things to run: air (oxygen), fuel and heat. It one of this components is taken away – the engine will quit. In the above case lack of air was caused the flameout. F-14 was flying above the permitted Mach number and the air intakes could not stabilize the incoming air. As a result – a lower amount of air was reaching combustion chambers and the fuel had not enough oxygen to sustain combustion.
On another occasion there was not enough fuel
Ok. I suffocated my engines. Let’s try if they will die of hunger. In F-14 it’s easy – just turn the plane upside down. The fuel does not flow to the feeder tanks at negative G (for example in inverted flight). That is why there are feeder tanks – they store the fuel that is required during negative g maneuvers. Manual states that feeder tanks will provide fuel for at least 10 seconds of flight on afterburner or at least 20 seconds at military power. What I quoted here is taken from the real world manual. I do not remember if Aerosoft’s manuals mentions this. It’s time to test what will happen. I roll my F-14, move throttle forward and then… before 20 seconds passed both engines quit. Just as they should have.
I was not able to create a flameout caused by the lack of heat. It may happen to any plane flying at idle or at very low power settings through a heavy precipitation. Such flameouts occur every few thousands flights in such conditions. I can not be sure that the F-14 does not simulate this situation – I only tried this a few times.
Earlier flameouts happened because the F-14 was improperly handled. Aerosoft’s aircraft passed both test with flying colors.
You may find it interesting that the flameouts caused by rain happened to some passenger planes descending in heady rain. There are some instructive stories from this incidents.
Test #2 compressor stall
Compressor stall or technically speaking – a surge happens when the airflow in a compressor is disturbed. The air slows down and at some occasions may even go back – causing flameout, and possibly damage or destruction of the engine.
How to damage F-14A’s TF30 engine?
There are plenty of possibilities! If you like to experiment and learn how the things work – you will love this plane. If you do not accept limitations and recommendations – you will end frustrated and sad (do not worry – you can turn failures off).
1. The first method for inducing engine stall is to interrupt the airflow. The easiest way to do this is to maneuver violently with engines at low speed. Thanks to F-14’s air intakes – it will properly suck the air into engine at nearly every angle of attack provided that the airflow is straight. Increase yaw abruptly and air will encounter intake wall on it’s way. Then you will hear a laud bang and the red Stall warning light will turn on. Sometimes both lights will turn on – and that means serious trouble.
2. At idle the same as above may happen also when the pitch is increased and the angle off attack changes. Bang and one engine quits…
3. The third way of inducing the engine stall is to close the throttle (back to idle) and then suddenly put it in military power position. Bang – engines quit leaving the pilot with a stupid face expression and a very heavy brick strapped to his back.
4. This will be more complicated. F-14 has inlet ramps that should be turned to auto before flight. The other position is “stowed”. Ramps control the airflow and stowed ramps should cause earlier stall. I did a simple test – stowing one ramp and leaving the second in auto position I accelerated to a supersonic speed. Bang – the engine quit. The other (ramps at auto) worked as it should. Nice!
Test #3 – great balls of fire – F-14 on fire
How to start a fire on an F-14? It’s easy. There is a foolproof method – pour some gas on a hot engine. How to do it in FSX (or a real F-14)? Turn one engine off and try to air-start it again. While you do that – put this engine’s throttle at 60 or 80% (pouring fuel into the engine). Is it nice by that fire your made?
The second option is a hot start while on the ground. Do everything by the book until you crank the engine. Then simultaneously crank it and move the throttle from cut-off position to idle (or higher) before you see any speed readouts. There are two options now – either you are lucky and this will be just a hot start or you will observe a hot start and a fire. In the first case the temperature will go high, you may hear a surge sound but then the temperature will drop and engine will work like it should (or will quit). The second option looks similar but the temperature stabilizes at max indication. Go bring that fire extinguisher…
Test #4 – what to do with a broken Tomcat
On the ground – send it for maintenance – it’s not your problem.
In the air – it’s more complicated. Cover your bases first. Start with the throttle of the affected engine. Move it to IDLE or Cut-off position. Then check if you are on fire. If so – pull the extinguisher handle. Then think about your options – check altitude and speed. It both are low – be prepared to eject.
Single engine Flameout
This is my first scenario. Altitude – 17.000ft. I reduce power and turn into a steep left turn. Flying just above the stall speed I turn rudder left. Due to disrupted airflow the left engine quits. Right engine produces additional yaw rate – stall is imminent.
Solution – I retard both throttles, push the nose down and correct yaw with opposite (right) rudder inputs. When the flight is stabilized in a shallow dive I cut-off the left engine fuel (retard the throttle, then right click left throttle to move it to off position), then advance (slowly) the right engine throttle to 80-90%. Slowly! – I do not want another engine flameout.
When the speed reaches 340 knots I reduce the power to idle (not necessary if you have dual throttles – I have a single), switch left engine throttle back to idle, stow inlet ramps (stowed allow for better airflow during engine start), then I make sure that the engine is turning (it should be turning at this speed), then I engage “air start” (on position).
It seems that the engine is trying to decide on what to do. That fascinates me in Aerosoft’s Tomcat – this procedure is a little different each time I try to air start the engine. Sometimes it will just start. At times it will even start with the ramps in auto position. And there are times when it will not start at all and the crossbleed is required.
In this case the engine started. Fuel flow indication changed. Temperature increased. After a moment I can slowly increase the power. To finish the procedure I switch inlet ramps to auto and air start to norm.
Test #5 – flameout in both engines, hydraulics and… ejection
Another scenario. I have a flameout in both engines. Now I am fighting with time (and altitude, and speed). If I can start a single engine or keep my speed over 300 knots – I will be ok. If not – it’s time to say goodbye to this F-14.
Lets consider the worst case scenario. I am low and I have nowhere to dive. Engines quit. And the airspeed is lower than 280 knots. I can see the hydraulic pressure indicator going down… and fast. In a moment I will not be able to move my controls.
What the (real) manual has to say about this situation? It can be summed up to this. In case of a surge in both engines electric installation may fail. Pilot needs to enable the emergency generator by resetting it (turn to off/reset and back to norm) – this generator should power engine indicators so that the pilot can assess his chances. Hydraulic power will be available only when both engines are turning at 11% speed or a single engine is turning at 18%. Pilot at his own discretion may decide to accelerate to over 350 knots in an attempt to restart the engines. If the air-start fails – the crew should eject at speed lower than 350 knots but before the aircraft looses it’s controls.
How does it work in Aerosoft’s F-14? Sustained engine stall is not simulated. The engine quits after a laud bang (I am not sure if some sounds that I heard were not caused by engine stalls that did not end in a flameout – it would be realistic). Emergency generator is not simulated properly. It’s either all dark or all lit up. There are few exceptions – systems that work even if there is no power in the system. Modern HUD will work. Wing sweep controls work no matter what.
In my opinion the hydraulic installation (and therefore the controls) quit too early. In most cases I have just enough time to put my Tomcat in a dive before I loose control and I regain it when the plane speeds up to 300-330KIAS.
So what should I do in my scenario?
- put the aircraft in a dive that will build up speed of 350kn
- throttles to idle
- ramps – stow
- air start – any engine
In case of lost control – eject. In case of low altitude and low speed – eject.
There are some cases of flameouts in both engines at high speed. Do not dive – just follow the other steps.
ENG CRANK – unreal
There is a bug or a cheat allowing pilot to start engine even at low speed. Just move ENG CRANK switch to the engine that should start – external source of compressed air will be connected and the engine will spool up it will also power the hydraulics pumps.
As I said – I do not know if that is a bug or a way to save unfortunate virtual pilots who are in trouble. If you do not like this option – just do not try it.
I like the F-14A and it’s TF30 engines. It’s a demanding plane and as far as I can compare it behavior to what I read about this aircraft – it is very realistic. In some respects it may even exaggerate the problems – the real world procedures and stories suggest that in some occasions when surge caused the flameout the real pilot would only experience engine stall that would pass.
At this point I am discussing features that are far beyond what is usually simulated in FSX. Most of Flight Simulator add-on aircraft do not simulate failures at all. Some have limited failures. This is one of a few planes that goes with it’s failures to the next level. Aerosoft tried to show us how the plane works and how it should not be operated. They succeeded – the aircraft is impressive.