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Engine basics => Engine set up tips => Topic started by: Matt Piatkowski on June 01, 2015, 07:21:00 AM
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Hello,
RO-Jett 76 rear exhaust for stunt may be equipped with Light Header Muffler shown on http://www.jettengineering.com.
This header muffler comes with the "Muffling Part".
I wonder if anybody tried to remove the "Muffling Part" and do this what I am going to do.
Please see the attachment.
Your comments are appreciated.
Thank you,
Matt
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I'm trying to figure out why you'd want to do this. I'd order a header, coupler and pipe from Randy, set the length per the chart, and go flying. I might also setup my plane to use either the pipe or the header muffler. Randy has a canister muffler that slides onto a standard header, FYI.
I asked PW recently about his experiences in a test I witnessed. I could not remember if it was a PA .75 or RO-Jett .76, but he was flying it at our old grass field (cow pasture). He said it was the RO-Jett, it was wonderful, but needed a lot of prop load (14"), which his ImpAct doesn't like...softer corner, you know. Maybe Windy can fix you up with a 12 x 4.5 five blade prop? Four blades might be enough, if they're wide blades. H^^ Steve
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Steve,
Let me explain what I am trying to do:
I will compare 76 with Lite Header Muffler to 76 with Lite Header ONLY connected to the pipe.
Light Header Muffler I am getting from Dub Jett, will have the "Muffling Part" not attached and I will play with it myself.
Specifically, I will install the "Muffling Part" in such a way that it will be removable and properly sealed while in place.
Lite Header has OD=7/8" and the coupler I have will allow me to connect it to the Windy's pipe.
There will be a minute mismatch of diameters ( Windy's pipe inlet OD is greater than 3/4 but smaller than 7/8 ) though.
Will this affect anything? I do not know therefore I will check it.
Windy's pipe I have is primarily a muffler ( cylindrical aft part ) and I may benefit from simply not having it in my next, large model.
Instead, I may use 76 with Lite Header AND the Muffling Part installed.
Weight savings will be around three oz. and everything will be simpler. When the prop is selected, all I will have to do is to get 4 cycling on the launch and fly.
Regards,
Matt
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Matt, I'm a bit lost as to what you're trying to accomplish other than lose a bunch of tail weight. I have been running a ROJETT .76 with a header & insert silencer. I'm here to tell you they run very steady this way & it will easily pull a 75 ounce plane through some wind. Go for it.
john
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Will this affect anything?
According to your diagram you will have a step in the gas flow at the start of the custom made adapter or where the ID narrows down.
Will this act as the first baffle or reflective wall? I kinda doubt it since it is tapered and should be no more disruptive than the normal flange to pipe weld (both rear and side exhaust) further up stream.
Or will the added volume of the header pipe interfere with the state of tune? No idea.
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John,
I always wanted to have large planes and 75 oz. leaves plenty of room for strong, stiff structure.
One of the guys I fly with bought Ro-Jett 90 (or 91?) last year and I cannot wait to see his monster-stunter ( needs painting ) pulling him out of the circle.
Chris,
I have similar questions but that's the whole point, at least for me.
I try here and try again there and try something else somewhere else and finally I know a bit more than before.
Greets,
M