Retro Jet Turbine stopping
11-03-2015, 07:55 AM
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Retro Jet Turbine stopping
Hello, I am looking for some help, if anyone has any ideas. I have a Retrojet 75 with a p70. With the wing off the turbine runs perfectly. When I put the wing on the turbine will run for about a minute and run down and stop. Having checked all the normal things I am left with the thought that the mesh I put over the intakes to act as a FOD guard is restricting the air. The mesh is quite fine. Any help appreciated. Thanks
11-04-2015, 07:52 AM
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"It is best to orient the UAT with the cap facing forward, brass nipples up, and the front end elevated about 20 degrees or more". (see attached out-of-focus photo) Your UAT appears to be mounted horizontally and elevated 0 degrees.
Also, you've got those black nylon ties securing your fuel line onto the UAT. I did that on the first install of the fuel system in my Reaction. Went to fly it with a CD witness to get my waiver and was told to remove the black ties and use safety wire instead. Apparently there can be gaps that air can seep through if you use the nylon ties. So .... not wanting to argue with the CD .... I removed all the black nylon ties and used safety wire instead. And now it runs great. But it ran great with the nylon ties too - whatever. But I'm a jet newbie so I will listen to those with more experience than me.
Last edited by oliveDrab; 11-04-2015 at 08:13 AM.
11-04-2015, 08:23 AM
#9
My Feedback: (57)
The instructions that came with my BVM UAT say:
"It is best to orient the UAT with the cap facing forward, brass nipples up, and the front end elevated about 20 degrees or more". (see attached out-of-focus photo) Your UAT appears to be mounted horizontally and elevated 0 degrees.
Also, you've got those black nylon ties securing your fuel line onto the UAT. I did that on the first install of the fuel system in my Reaction. Went to fly it with a CD witness to get my waiver and was told to remove the black ties and use safety wire instead. Apparently there can be gaps that air can seep through if you use the nylon ties. So .... not wanting to argue with the CD .... I removed all the black nylon ties and used safety wire instead. And now it runs great. But it ran great with the nylon ties too - whatever. But I'm a jet newbie so I will listen to those with more experience than me.
"It is best to orient the UAT with the cap facing forward, brass nipples up, and the front end elevated about 20 degrees or more". (see attached out-of-focus photo) Your UAT appears to be mounted horizontally and elevated 0 degrees.
Also, you've got those black nylon ties securing your fuel line onto the UAT. I did that on the first install of the fuel system in my Reaction. Went to fly it with a CD witness to get my waiver and was told to remove the black ties and use safety wire instead. Apparently there can be gaps that air can seep through if you use the nylon ties. So .... not wanting to argue with the CD .... I removed all the black nylon ties and used safety wire instead. And now it runs great. But it ran great with the nylon ties too - whatever. But I'm a jet newbie so I will listen to those with more experience than me.
We also have not heard back from the OP.
11-04-2015, 08:43 PM
#10
Raptor. I need to be blunt.. Get rid of everything you have installed between the trap and the pump.. the pump has a 6mm nipple on it. Gaspar gives us a suction filter and you can put it between the trap and filter. get rid of the cutoff and the tygon.. I think you are pulling the tygon flat.
For the cutoff valve, just put a 4mm or jet cat valve on the output line to the motor for AMA legality. Not on the input line.. I lost a jet that way.
Next look at your vent lines.. Its possible you are suctioning the air out of the tanks.. very likely.. place the vent ever so slightly into the wind or if its straight down, just use a brass tubing to clear the aircraft and cut it at 45 degrees into the relative wind.
Lastly, mount the air trap at an angle with the nipples on top
If you are using an air trap and a felt clunk, lose the felt clunk, or at least drill it out
If suction or pressure drops in the tank system, the pump cannot keep up. That can cause slow response.
Finally, go through the fuel system and make sure that all the barbs and connectors have large openings and that there isn't some slag or brass casting that is blocking any opening.. seen it many times.. good luck.. i fought this problem on my rookie, and it was the felt clunk and the fuel connector had brass overcasting..
on my first élan, it quit due to suction on a 6mm festo exactly like you have yours.. it later had a vent problem, so someone showed me the trick of the brass vent with 45 deg into the wind..
For the cutoff valve, just put a 4mm or jet cat valve on the output line to the motor for AMA legality. Not on the input line.. I lost a jet that way.
Next look at your vent lines.. Its possible you are suctioning the air out of the tanks.. very likely.. place the vent ever so slightly into the wind or if its straight down, just use a brass tubing to clear the aircraft and cut it at 45 degrees into the relative wind.
Lastly, mount the air trap at an angle with the nipples on top
If you are using an air trap and a felt clunk, lose the felt clunk, or at least drill it out
If suction or pressure drops in the tank system, the pump cannot keep up. That can cause slow response.
Finally, go through the fuel system and make sure that all the barbs and connectors have large openings and that there isn't some slag or brass casting that is blocking any opening.. seen it many times.. good luck.. i fought this problem on my rookie, and it was the felt clunk and the fuel connector had brass overcasting..
on my first élan, it quit due to suction on a 6mm festo exactly like you have yours.. it later had a vent problem, so someone showed me the trick of the brass vent with 45 deg into the wind..
11-05-2015, 03:22 AM
#11
My Feedback: (41)
THANK YOU VERY MUCH..
i was thinking not enough air to engine from intakes.
when i use cooling blower into intakes ,very little air goes to engine.
leaks out into fuse around fuel tank. i will make changes.
fuel filter after pump?
I will make changes
I have felt clunk , wavy paper with brass ends
i was thinking not enough air to engine from intakes.
when i use cooling blower into intakes ,very little air goes to engine.
leaks out into fuse around fuel tank. i will make changes.
fuel filter after pump?
I will make changes
I have felt clunk , wavy paper with brass ends
Last edited by RAPPTOR; 11-05-2015 at 03:33 AM.
11-05-2015, 06:18 AM
#14
There are a lot of opinions on fuel filter before or after the pump.. Gaspar strongly recommends to use the festo 6mm filter before the fuel pump.. he says a large majority of the pump failures are due to FOD entering the fuel pump. who am I to argue that?
The other camp says the fuel pump puts off small shavings, so filter after the pump. so Make your own decision..
its possible you don't have enough exit area behind the motor and that would cause issues, and its also possible.. let us see your engine install
Ya, when using the air trap, you normally just use a heavy clunk.. very likely thats the issue.. the pump is having to overcome a lot to work..also make sure your vent line is clear and open. let us see that too..
Good luck..
The other camp says the fuel pump puts off small shavings, so filter after the pump. so Make your own decision..
its possible you don't have enough exit area behind the motor and that would cause issues, and its also possible.. let us see your engine install
Ya, when using the air trap, you normally just use a heavy clunk.. very likely thats the issue.. the pump is having to overcome a lot to work..also make sure your vent line is clear and open. let us see that too..
Good luck..
11-05-2015, 07:29 AM
#15
The instructions that came with my BVM UAT say:
"It is best to orient the UAT with the cap facing forward, brass nipples up, and the front end elevated about 20 degrees or more". (see attached out-of-focus photo) Your UAT appears to be mounted horizontally and elevated 0 degrees.
Also, you've got those black nylon ties securing your fuel line onto the UAT. I did that on the first install of the fuel system in my Reaction. Went to fly it with a CD witness to get my waiver and was told to remove the black ties and use safety wire instead. Apparently there can be gaps that air can seep through if you use the nylon ties. So .... not wanting to argue with the CD .... I removed all the black nylon ties and used safety wire instead. And now it runs great. But it ran great with the nylon ties too - whatever. But I'm a jet newbie so I will listen to those with more experience than me.
"It is best to orient the UAT with the cap facing forward, brass nipples up, and the front end elevated about 20 degrees or more". (see attached out-of-focus photo) Your UAT appears to be mounted horizontally and elevated 0 degrees.
Also, you've got those black nylon ties securing your fuel line onto the UAT. I did that on the first install of the fuel system in my Reaction. Went to fly it with a CD witness to get my waiver and was told to remove the black ties and use safety wire instead. Apparently there can be gaps that air can seep through if you use the nylon ties. So .... not wanting to argue with the CD .... I removed all the black nylon ties and used safety wire instead. And now it runs great. But it ran great with the nylon ties too - whatever. But I'm a jet newbie so I will listen to those with more experience than me.
Back in my rookie, the pump had a hard time pulling fuel, so it was slow to respond and slow to start.. If yours runs good on the ground but not in the air, then zero in on something restricting the ability of the motor to pull air or fuel.. its one of those two issues.
Last edited by gooseF22; 11-05-2015 at 07:37 AM.
11-05-2015, 07:44 AM
#16
I have also had a couple of flameouts on my Retrojet. They also seemed unexplainable to begin with. Or at least, I did not understand them. They all occurred after some minutes of flight and on low effect. I finally decided that they were due to a new paper fuel filter in my filling equipment and after changing filter to one with a nylon mesh and cleaning out the whole fuel system the problem did not reaper. Not this far at least.
Judging from your pictures I don´t think that your problem stems from the fod mesh but what do I know. In my model I have chosen to use a standard fod mesh mounted on the engine and nothing in the inlets. But I don´t think it matters, our small engines don´t use up an awful lot of air anyway.
All that said I do like the Retro. I built it after I totaled my Eurosport and lost my all my self-confidence. It has been very useful as a confidence builder and helped me back to the flight line again. And this winter I am finishing a new Eurosport
If you like you can have a look at my model and its maiden flight at YouTube.
https://www.youtube.com/watch?v=jdoPg7s15yc
Hope you solve your problem.
Jannica in Sweden
Judging from your pictures I don´t think that your problem stems from the fod mesh but what do I know. In my model I have chosen to use a standard fod mesh mounted on the engine and nothing in the inlets. But I don´t think it matters, our small engines don´t use up an awful lot of air anyway.
All that said I do like the Retro. I built it after I totaled my Eurosport and lost my all my self-confidence. It has been very useful as a confidence builder and helped me back to the flight line again. And this winter I am finishing a new Eurosport
If you like you can have a look at my model and its maiden flight at YouTube.
https://www.youtube.com/watch?v=jdoPg7s15yc
Hope you solve your problem.
Jannica in Sweden
11-05-2015, 12:22 PM
#19
11-05-2015, 01:34 PM
#21
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One way to determine if you have restrictions in the fuel line is to check you pump voltage with your GSU. I don't know the max or normal voltage for your engine but I believe most run in the 3.5 to 4.5 volts max.
K.O.
K.O.
11-07-2015, 03:43 AM
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Thank you for asking "Tothemax". A lot of thoughts came out from all the inputs. I did not have any pinched lines and ripped out the wire mesh , checking it against a FOD guard the mesh was very fine perhaps too fine.. I stripped everything out before I could get a picture for Dave Wilshere. Everything rebuilt and ready for a test and hopefully a flight. If no good then back to the forum. Thanks everyone