stunthanger.com
Engine basics => Engine set up tips => Topic started by: Mike Scholtes on October 06, 2017, 04:29:50 PM
-
There is maybe 3/16 clearance between the exhaust header (Randy Smith item) on the PA40UL and the front edge of the metal all-tubes-forward 5 oz tank in nose of my new (unflown) Oriental Plus. This would be the hottest part of the header, just past joint between header and engine case. I am concerned this may pose a problem for heating the tank, maybe to a dangerous level. This my first RE piped plane so not sure what to expect.
Would it be advisable to place a sheet metal reflector or something between header and the tank? The header is only uncomfortably close for a short distance where it passes the tank end at about a 45 degree angle. Cowl has good ventilation and cooling holes where header joins pipe.
Am I being paranoid, or just normally noid?
-
There is maybe 3/16 clearance between the exhaust header (Randy Smith item) on the PA40UL and the front edge of the metal all-tubes-forward 5 oz tank in nose of my new (unflown) Oriental Plus. This would be the hottest part of the header, just past joint between header and engine case. I am concerned this may pose a problem for heating the tank, maybe to a dangerous level. This my first RE piped plane so not sure what to expect.
Would it be advisable to place a sheet metal reflector or something between header and the tank? The header is only uncomfortably close for a short distance where it passes the tank end at about a 45 degree angle. Cowl has good ventilation and cooling holes where header joins pipe.
Am I being paranoid, or just normally noid?
We have run them a lot closer (including touching the tank) with no real problems. Touching is not recommended, but unless it starts getting richer and richer as the run goes on due to the fuel being heated, probably no problem.
Brett
-
Am I being paranoid, or just normally noid?
I think you're just Renoid Mike. Reasonably noid. If it makes you feel better, a strip of thin aluminum sheet could be placed in the gap as a heat sink if you can find a convenient way to anchor it.
What's the "Plus" part of this Oriental?
Rusty
-
Mike, FWIW I've had some success with engine headers passing in close proximity to the tank by using a balsa "shim insulator" between the exposed tank surface and the header. This included when running the Rustler .40 with the rear oriented muffler installation which put the muffler directly over the tin tank. I felt the heat may have contributed to a reduction in fuel viscosity over the length of the engine run making the run inconsistent. Balsa is a very good insulator and I've used just 1/8" sheet (with fuel proofing surface just in case) and it seemed to provide a solider engine run from beginning to end.
As Brett has said, however, we have run many a tuned pipe header in close proximity to tanks for many years with no special attention and have been reasonably successful.
My suggestion would be if you experience any inconsistency that you experiment with an insulator as described above...don't weigh nuttin' and can't do any harm.
Ted
-
Thanks everyone, that gives me some confidence I won't be flying a balsa Hindenburg. Re balsa, it had not occurred to me to use good old balsa as an insulator. May be a good idea just to wedge everything in place.
-
While we're on the subject, there is little room to change tank height in this model. If mounted on the engine bearers the tank feed line at rear of tank and presumably the rear "bubbler" end of the uniflow line will be about 1/8 above (vis a vis ground with model on wheels) the needle valve/fuel intake on the venturi. Is this a reasonable starting place for the PA40UL on uniflow?
Re what is "plus" about this Oriental, it is nothing like the classic straight-wing Oriental from long ago. It is a modern design built for piped 40 from the outset. As for what is "Oriental" about it, beats me. Dee Rice design, RSM kit. I enlarged the tail volume to be 22% of wing area.