Pegasus flameout
07-19-2002, 03:35 PM
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Pegasus flameout
Help!!!!!!! I just had a flameout in my BVM f100D. Has anyone had an EGT probe blow-out??? After the flameout I inspected the airplane for heat damage and found that the EGT probe was ruptured about 1/2" from it's end. I've ordered another one but I'm concerned about heat damage to the engine its self.
If there was enough heat to rupture the probe, maybe it got hot enough to fry the engine.
As to the reason for the flameout Bob Violet says that he also had this problem with his F model. I told him that during acceleration that i thought i could hear the engine compressor stalling just before it flamed out. I was holding the model by the nose and could feel the front of the fuse vibrating in sync with the compressor stalling. This leads me to believe that under heavy acceleration the duct is vibrating hard enough to set up turbulent flow through the engine causing the flameout. What do you think?
If there was enough heat to rupture the probe, maybe it got hot enough to fry the engine.
As to the reason for the flameout Bob Violet says that he also had this problem with his F model. I told him that during acceleration that i thought i could hear the engine compressor stalling just before it flamed out. I was holding the model by the nose and could feel the front of the fuse vibrating in sync with the compressor stalling. This leads me to believe that under heavy acceleration the duct is vibrating hard enough to set up turbulent flow through the engine causing the flameout. What do you think?
07-19-2002, 05:50 PM
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Pegasus flameout
It is normal to get vibration at the inlet if you are holding the model. The influx of a large volume of air causes tubulence, especially with the sharp inlet lips on the F-100. This tubulence should smooth out somewhat during flight as air is rammed in under higher velocity.
As for the EGT probe. It takes a lot of heat to rupture it. I've had an engine get as high as 900 degrees C, and the probe was fine. Take the engine out, and put it on a test stand and run it. Check for any abnormalities.
What was the highest temperature recorded by the ECU before the probe gave up the ghost? That will give you an idea how hot it got.
As for the EGT probe. It takes a lot of heat to rupture it. I've had an engine get as high as 900 degrees C, and the probe was fine. Take the engine out, and put it on a test stand and run it. Check for any abnormalities.
What was the highest temperature recorded by the ECU before the probe gave up the ghost? That will give you an idea how hot it got.
07-19-2002, 06:36 PM
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Pegasus flameout
Most likely what happed is, very simple... the turbine hung up.
What this means is during acceleration, (exp when its hot
out side) the engine can't burn all the fuel and
some of the fuel starts burning outside the cumbustion chamber.
Like inside you tail pipe. This will make the whole plane "Rumble"
This somewhat commen with the Pegasus/Olympus.
I think the EGT probe died during the hang up.
It is possiable to get a Pegasus to compressor stall
but it seems to only happend at above 80,000 RPMs during
super fast acceleration.
If you turbine was hanging up, it happend at %30 to %50
RPMs
It is very unlikely you turbine was damaged.
Just check your tail pipe.
If you are flying and this happens, just pull the power back
to %20 percent, wait 1 sec, the power up one or two clicks
at a time, (very slowly) it should go to full power no problem.
I sugest you try to reproduce the problem at night, if blue
fire shoots out the back, there is no question, it hung up.
Send it to AMT, they will most likely change the cumbustion chamber. I have fixed this problem on my Pegasus
engines, by bending the first row holes forward, in the cumbustoin chamber. I am only about %50
getting them to work. I made one so fast
it would out acc a mercury. (well allmost)
Hope this helps
Eddie Weeks
http://www.corpcomp.com/weeks1/
What this means is during acceleration, (exp when its hot
out side) the engine can't burn all the fuel and
some of the fuel starts burning outside the cumbustion chamber.
Like inside you tail pipe. This will make the whole plane "Rumble"
This somewhat commen with the Pegasus/Olympus.
I think the EGT probe died during the hang up.
It is possiable to get a Pegasus to compressor stall
but it seems to only happend at above 80,000 RPMs during
super fast acceleration.
If you turbine was hanging up, it happend at %30 to %50
RPMs
It is very unlikely you turbine was damaged.
Just check your tail pipe.
If you are flying and this happens, just pull the power back
to %20 percent, wait 1 sec, the power up one or two clicks
at a time, (very slowly) it should go to full power no problem.
I sugest you try to reproduce the problem at night, if blue
fire shoots out the back, there is no question, it hung up.
Send it to AMT, they will most likely change the cumbustion chamber. I have fixed this problem on my Pegasus
engines, by bending the first row holes forward, in the cumbustoin chamber. I am only about %50
getting them to work. I made one so fast
it would out acc a mercury. (well allmost)
Hope this helps
Eddie Weeks
http://www.corpcomp.com/weeks1/
07-19-2002, 06:45 PM
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Pegasus flameout
I had the same thing happen with my RAM 500, only on very hot days. Of course, it's out in the open on my BobCat, so no damage. But it is somewhat frightening the first time it happened.
