Avoid the flame out by overspeeding!

[NORTHMAN]

While flying the MiG-21 to intercept something, I overspeed so many time!:( Is there a way to avoid the overspeeding flame out thing and cruise around mach 2? The way I do it is maintaining the afterburner low and shuting it up from time to time!Is there a way to do it more efficiently?

[Ryan Legend]

The way I do it is maintaining the afterburner low and shuting it up from time to time!Is there a way to do it more efficiently?

 

Nope, sorry mate. I think this is the only way to do it. A real shame though, it would be such a relief to not worry about overspeeding.

[SilentGun]

What altitude are you cruising at?

[NORTHMAN]

between 8000 and 12 000 meter! but sometime higher, reaching 15 000. It's easier at higher altitude!:thumbup:

[Art-J]

Oh, It's possible to balance the afterburned thrust and drag at Ma 2 - 2.05 by keeping the EGT at about 680'ish degrees, but it's balancing on a very thin line!

[Dirty Rotten Flieger]

I am very happy to tell you that yes there is a better way !

 

Switch the nose cone to manual and set it at about 30% . Well that is a little simplistic because it depends on what your altitude is but the idea is that you look at what the automatic setting is before you switch it to manual and reduce it a little. If I am flying at about 12000m altitude at Mach2 the nose cone will be around 40%. If you are flying higher it will be higher %. Just reduce it a little and your max speed will be limited so you can concentrate on situational awareness.

 

I also reduce burner power so the tail pipe temp is about 700 degrees but even if you run the burner full your speed can be limited with the nose cone.

 

I just love speeding over the top of those F15's online and getting away at 2M ! F15 carry so many missiles they are too draggy to catch the little Mig21.

 

Good luck !

Edited August 21, 2015 by Dirty Rotten Flieger

[xxJohnxx]

Switch the nose cone to manual and set it at about 30% . [...]

 

I guess that works, but it doesn't seems to be very realistic...

[Manuel_108]

Lol, I imagine that a big f***up could happen if a real pilot just casually manipulates the nose cone at M2.0 Haha

Edited August 21, 2015 by Manuel_108

[Art-J]

I have to take back what I wrote a week ago, four posts above. Today, for the first time in months I did a max speed test at ~10k meters, but, it seems something has inadvertently changed in one of recent patches, because balancing the thrust and drag at Ma 2.05, which was "just" difficult previously, became next to impossible now.

 

The previous ~680 degrees EGT trick doesn't seem to work anymore, as the plane happily accelerates to flameout even at ~665.

 

Can't wait for 1.5 improvements and fixes :D !

[FSKRipper]

While flying the MiG-21 to intercept something, I overspeed so many time!:( Is there a way to avoid the overspeeding flame out thing and cruise around mach 2? The way I do it is maintaining the afterburner low and shuting it up from time to time!Is there a way to do it more efficiently?

 

Nope, sorry mate. I think this is the only way to do it. A real shame though, it would be such a relief to not worry about overspeeding.

 

I know it's hard to get started with such things but you two missed a very emotional thread regarding the flight model in late 2014 were most people demanded to remove the artificial speed limit of the MiG-21. This was done, the result is flameout/engine damage to overspeeding which is realistic behaviour. I must admit that I don't know if something was changed (or broke) during the last patches but it has passed some time since I saw a MiG-21 changelog...

[Dirty Rotten Flieger]

Lol, I imagine that a big f***up could happen if a real pilot just casually manipulates the nose cone at M2.0 Haha

 

WEll yes you can try it and see for yourself. If you extend the nose cone to maximum,like 90%, the engine will start to surge, the extra inlet doors on the sides will noisily bang open and closed, and the engine may flame out . If you lower the nose cone extension % below the amount the automatic system has it set to, the plane will simply slow down.

 

The is no danger to the engine to switching from automatic to manual and stopping it from automatically extending further when you reach mach 2.

[Manuel_108]

Awesome, will do that in the future during cruise.

[lokodehortaleza]

I am very happy to tell you that yes there is a better way !

 

Switch the nose cone to manual and set it at about 30% . Well that is a little simplistic because it depends on what your altitude is but the idea is that you look at what the automatic setting is before you switch it to manual and reduce it a little. If I am flying at about 12000m altitude at Mach2 the nose cone will be around 40%. If you are flying higher it will be higher %. Just reduce it a little and your max speed will be limited so you can concentrate on situational awareness.

 

I also reduce burner power so the tail pipe temp is about 700 degrees but even if you run the burner full your speed can be limited with the nose cone.

 

I just love speeding over the top of those F15's online and getting away at 2M ! F15 carry so many missiles they are too draggy to catch the little Mig21.

 

Good luck !

 

This works, I just did a fast run with a clean aircraft at 13.000 meters, set SAU to recovery, full AB (without emergency AB), nosecone set manually to 35%. The Mig will reach 2200 Km/h TAS and then keep accelerating very slowly until flameout at over 2250 Km/h, after several minutes. You can easily avoid flameout with small throttle adjustments.

 

Thanks for the tip! :thumbup:

[JorgeIII]

I know it's hard to get started with such things but you two missed a very emotional thread regarding the flight model in late 2014 were most people demanded to remove the artificial speed limit of the MiG-21. This was done, the result is flameout/engine damage to overspeeding which is realistic behaviour...

 

Why do you say that? Only by reading about mig-21 models: engine, weight and speed evolution you will notice the plane is not overpowered and it doesent easily overspeed. Speed records where not easily achived. AFAIK the scripted speed limit was wrong and current overspeeding is wrong too. For more specifics look its aceleration/G chart at 1G. You can also read the real mig-21 manual procedure to try to achive max speed and how this is not always possible.

 

Until it is fixed, this is what I found helpfull:

 

1) As stated above, i manually place the nosecone needle between 3.5 and 4.0, when the plane reaches mach 1.9 I switch the nosecone to manual and it stops accelerating at about mach 2.05. When I slow down the switch goes back to auto.

 

2) As suggested by Dolfin here: http://forums.eagle.ru/showthread.php?t=136200&page=3

You can use some curve in the throttle axis. You will be able to manage precisely AFT and exhaust temp.

Even so, above 660 degrees a clean plane will speedup until overspeeding and below 660 it will slow down to submach speed.

Edited August 23, 2015 by JorgeIII

[Nerd1000]

Why do you say that? Only by reading about mig-21 models: engine, weight and speed evolution you will notice the plane is not overpowered and it doesent easily overspeed. Speed records where not easily achived. AFAIK the scripted speed limit was wrong and current overspeeding is wrong too. For more specifics look its aceleration/G chart at 1G. You can also read the real mig-21 manual procedure to try to achive max speed and how this is not always possible.

 

Until it is fixed, this is what I found helpfull:

 

1) As stated above, i manually place the nosecone needle between 3.5 and 4.0, when the plane reaches mach 1.9 I switch the nosecone to manual and it stops accelerating at about mach 2.05. When I slow down the switch goes back to auto.

 

2) As suggested by Dolfin here: http://forums.eagle.ru/showthread.php?t=136200&page=3

You can use some curve in the throttle axis. You will be able to manage precisely AFT and exhaust temp.

Even so, above 660 degrees a clean plane will speedup until overspeeding and below 660 it will slow down to submach speed.

 

The general issue here is that as forward velocity increases the ram pressure and therefore thrust of the engine increases as well, given a constant altitude. Ram drag rises as well, but apparently not at the same rate as pressure at the entrance to the compressor. When you set the inlet cone to manual you are preventing the cone from moving forward and keeping the shockwave it creates focused on the inlet lip as your speed increases. The pressure recovery of the inlet therefore drops as speed rises, reducing the amount of thrust you can produce and limiting your speed.

 

 

IRL the speed limit is usually set by the maximum operating temperature of the blades in the final stage of the compressor. I can't see any reason that the engine should flame out when you exceed a certain speed- Exceeding Mach 2.1 doesn't suddenly stop the fuel in the combustor burning. AFAIK the RL consequence of exceeding the speed limit would be damage to the compressor blades, eventually leading to failure (read: snapping off and flying through the engine in a manner similar to fragments from an artillery shell). Alternatively, the nosecone might delaminate or burn, seeing as it is made from plywood.

[Art-J]

All and all, any movable shockwave control devices, whether cones on MiG-21, Mirage etc. or plates on Eagle, Tomcat etc. were operated automatically by default and were switched to manual (if possible) only in emergency situations when auto- got fudged.

 

If we have to use manual to maintain some constant, high Mach number, then flight/system modelling most likely needs some further tuning.