stunthanger.com
Engine basics => Four strokes only => Topic started by: steven yampolsky on July 26, 2013, 01:23:21 AM
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When building a model originally designed for a piped motor, say PA 61 or similar, is there a general rule of thumb for adopting it to 4S use? Do I shorten the nose? Add a prop extension?
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56/62 not necessary, 72 probably. 72 is 2 ounces heavier than the 62. You will find the airplane will turn just as well with the CG farther forward than needed with a 2s.
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You will find the airplane will turn just as well with the CG farther forward than needed with a 2s.
Because the CG in-flight is in the same place.
Brett
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Because the CG in-flight is in the same place.
Brett
Less fuel, right?
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The issue of the nose length on the 72 is not really an issue as Claudio can attest because when we build for the 72, we are almost always going from scratch. Consequently, the nose will be in proportion to the rest of the plane.
If the plane is a typical full size stock stunter; say an Impact,Trivial Pursuit etc. where you would normally have a 10.5" nose, a 9.5" inch nose will do you fine on the 72. The main issue is not the nose. If you don't know what you are doing with the 72, the motor can blow your plane apart in flight.
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Steven: I have built and flown many 4S planes over the years. I have never
found it necessary to shorten the nose. I built two Saturns with OS 52 FS
power and didn't shorten the nose on either one and they were very good
performers. The only plane I shortened the nose on was a profile P-40 that
was my first 4S plane; it had a Saito 56 for power. I didn't like the way this
plane flew and immediately wished I hadn't shortened the nose. I don't think
it's necessary at all.
Steve