comment and question from a friend of mine led to this opening portion of my column. His ques- tion was to the effect that “could a person put a pipe on an engine which is bolt- ed to a profile fuselage”? Not too long after that I ran across some color pictures which I scanned and will use to answer his query. I built a Twister and placed a pipe on the OS Max .40 FP as Jim Krueger did in the late ’90s. My copy of his engine/pipe combination is one that Jim used on a Twister painted up to resemble a Stuka with an all-black paint scheme and German crosses. I painted mine in white, red, black, and blue. The theme of my Twister was the “Chi-Town Twister” named after a famous ’60s race car based out of Chicago.
C/LStunt A
The only modification that I made to the basic airframe was to add taller and stronger horns to the flaps and elevators. The taller horn, on both the flaps and ele- vators was to allow the system to work longer and better while slowing down the control movement. Other than that, the Sig kit was stock in nature and flew very well. It eventually made its way to the model stable of Byron Barker. Byron was satisfied with the performance of the mod- el although I removed the pipe and placed a tongue muffler on the FP engine. Byron was not sure about running a pipe combi- nation so the change was made to keep him comfortable. I liked the way the pipe combo ran and would have kept it if I had not passed it on to Byron.
The setup utilizes a header part of the OS Max Universal Silencer Assembly (for 35 FP or 40 FP), part number 883 and packaged as code number 72113000. The package includ- ed a header which bolts to the exhaust, a clear tube to move the exhaust to the exter- nal muffler and assembly items. I do not know if this setup is still available but per-
by allen brickhaus You can reach Allen Brickhausat PO Box 206, Golconda, Illinois 62938, or via e-mail at
abkb801@shawneelink.net
PHOTOGRAPHY: ALLEN BRICKHAUS
The Chi-Town Twisteris sitting ready to fly at Golconda International Model Field with its OS Max 40 FP and an early version of a Randy Smith pipe. The text will give the information on the header attachment.
haps a side to rear custom header could be substituted in its place.
The earlier smaller diameter pipe sold from Randy Smith will work just fine. Call him for updated specs (678-407-9376 or email at
randyaero@msn.com). I set my pipe so the first baffle was at 17.5 inches behind the center of the plug location on the OS Max .40 FP. I used a Rev-UP 10–4 prop with a release rpm of about 9800. A line length of 60 feet, measured from eyelet to eyelet flew the Twister at a 5.2 lap time. A current Zinger Pro 10–4 or 10–5 would also work. Even an NOS Grish grey 9–4 would possibly work.
Your final rpm setting and lap times will vary depending upon your own combination.
The .40 LA and .46 LA will also suffice as ex- cellent powerplants and test bed situation. As to the final setting of the pipe, check the lap times at the third or fourth lap after take-off. Then check the lap times about one or two laps after your last maneuver. If the lap times become shorter, then lengthen the pipe location aft of the glow plug. If the lap times are longer at the end of the pattern, shorten the pipe.
Any of these non-ball bearing engines, but with ABC, ABN or AAC pistons and liners, could use a standard 5% to 10% nitro fuel with an oil base of 20%, with half being cas- tor and half being synthetic. Any of these non-ball bearing engines will give you good service, but a ball bearing powerplant will
This is the full package of the OS Max Universal Silencer Assembly (above left) as described in the column. Allen only used the header portion of the package but the other parts can be very useful in future projects, including scale
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outlets. This shot (above right) shows how the header is used on the Chi-Town Twister and how it funnels the exhaust to the Randy Smith small diameter carbon fiber pipe.
SEPTEMBER 2013
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