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Engine basics => Engine set up tips => Topic started by: Allen Eshleman on March 19, 2012, 11:11:02 PM
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On Sunday I worked on a project for my son's science fair project: to test several different fuels, comparing the runs I would get.
I had an O.S. FP 40 on a Nobler.
Brodak 5% nitro, 11.5% synthetic, 11.5% castor good run, great power in first half of flight, seemed to lag a bit coming out of the outside loop on the second half of the run.
Brodak 10% nitro, 11.5% synthetic, 11.5% castor great run, great power through the whole flight (needle 2 clicks open from previous run)
faster
Fox 10% nitro, 20% castor Motor fired but wouldn't start didn't have time to try with needle further open
Tower 10% nitro, 18% synthetic Motor wouldn't fire or start
Any ideas as to why the problems with the last two fuels. Both are old. The Brodak fuel is fresh
Would all castor cause one to need to open the needle? I want to try again, especially with the Fox fuel. Would the Tower fuel be too lean and too dangerous because of the lesser amount of lubricant?
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There is no reason that the other fuels would not fly the plane and run the engine unless they were really old..or really contaminated, your test is not really anything but a test of good fresh fuel vs, old bad fuel it seems.
maybe try the test again with all fuels being equal
Randy
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Silly question maybe, but is the plug OK? It's very strange that it wouldn't even fire.
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I have used properly stored (tightly capped and in the dark) Fox fuels that were many years old, and they ran fine.
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On Sunday I worked on a project for my son's science fair project: to test several different fuels, comparing the runs I would get.
I had an O.S. FP 40 on a Nobler.
Brodak 5% nitro, 11.5% synthetic, 11.5% castor good run, great power in first half of flight, seemed to lag a bit coming out of the outside loop on the second half of the run.
Brodak 10% nitro, 11.5% synthetic, 11.5% castor great run, great power through the whole flight (needle 2 clicks open from previous run)
faster
Fox 10% nitro, 20% castor Motor fired but wouldn't start didn't have time to try with needle further open
Tower 10% nitro, 18% synthetic Motor wouldn't fire or start
Any ideas as to why the problems with the last two fuels. Both are old. The Brodak fuel is fresh
Would all castor cause one to need to open the needle? I want to try again, especially with the Fox fuel. Would the Tower fuel be too lean and too dangerous because of the lesser amount of lubricant?
Hmmmm...Sounds like some other problem developed between the 2nd and last tests. Did you try the Brodak fuel again after the others?
Water in the other fuels or a blocked filter or bad plug or bad starter battery are the most likely suspects!
Randy Cuberly
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Hmmmm...Sounds like some other problem developed between the 2nd and last tests. Did you try the Brodak fuel again after the others?
Water in the other fuels or a blocked filter or bad plug or bad starter battery are the most likely suspects!
Randy Cuberly
I would also think that a complete test would check not only the fuel, but either a variety of engines, or at least one engine that's known to have high compression and a handful of compression shims.
(If you're going to try the high nitro/high compression corner of this space, be sure to have plenty of glow plugs on hand).
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On Sunday I worked on a project for my son's science fair project: to test several different fuels, comparing the runs I would get.
I had an O.S. FP 40 on a Nobler.
Brodak 5% nitro, 11.5% synthetic, 11.5% castor good run, great power in first half of flight, seemed to lag a bit coming out of the outside loop on the second half of the run.
Brodak 10% nitro, 11.5% synthetic, 11.5% castor great run, great power through the whole flight (needle 2 clicks open from previous run)
faster
Fox 10% nitro, 20% castor Motor fired but wouldn't start didn't have time to try with needle further open
Tower 10% nitro, 18% synthetic Motor wouldn't fire or start
Any ideas as to why the problems with the last two fuels. Both are old. The Brodak fuel is fresh
Would all castor cause one to need to open the needle? I want to try again, especially with the Fox fuel. Would the Tower fuel be too lean and too dangerous because of the lesser amount of lubricant?
Castor is much more viscous than most synthetics and will require the needle to be more open to pass the same volume.
Brett
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Thanks for the advice.
I intend to try again with a different starter battery and glow plug if necessary.
I will also open the needle for the all castor fuel. I thought that it had a higher viscosity.