Best fuel for power

[bstfrnd2bstfrnd]

Hey guys, I fly target drones for a local guy and the problen is they are HEAVY. The planes weigh in at about 80lbs and we use a US131 single cylinder engine. They have a 12 foot wingspan and we use a catapult but still lose alot of planes on launch. The planes that don't make it barely miss and are recoverable but it's a pain. It's not cost effective to try to change the engine or the exaust. So, I'm left with trying different fuel mixtures. Since you guys in racing are known for getting the most out of engines maybe ya'll have some suggestions. Remember that engine life is not a problem because ideally I only need about 5 minutes of runtime in the air. Worst case scenario would be two flights of about 30 minutes run time. I'm looking to get only 300 or 400 more RPMs. Any help is appreciated.

[Sparky69]

Do you have a picture? You leave a lot of unknows so we could play 20 questions or you could be a bit more forth coming.
Sparky

[XJet]

If your fuel system is up to it you could try changing to a blend of methanol/nitromethane and suitable oil. You'd have to richen things up quite a bit though and you'd get much shorter runs from a tank -- from half to 1/3 the current duration depending on the nitro percentage.

[bstfrnd2bstfrnd]

Give me a while and I'll find a link to the website
Try this link. I'm the guy with the hat. http://www.acmuav.com/

[Sparky69]

I tried the web site but on dial up it will not launch.
OK here is my take. It sounds like you only need to get the plane airborne. Since I am not sure of your configuration, Pusher or Tractor, Canard Delta or conventional, wing loading etc I would think if you are getting maximum power from your engine You might think about changing props static thrust is what I guess you are trying to improve. Maybe go down an inch in pitch.
What props are you using? Wood or composite? mfg?
Sparky

[JagerBomb]

I have had a lot of success using propylene oxide. You will need to richen the needles but it will make a decent increase in power. It is available though most race gas suppliers. http://www.motorsportsracingfuels.com/FAQ.html see question #8 on additives

Mark Trent

[bstfrnd2bstfrnd]

Thanks for the help. I'm not sure of the prop company but we have tried all the wooden(cheap) props and have settled on I think a 25x12.
I'll go to our local speed shop and purchase some propylene oxide and let you know how the test run goes. This will take a couple of days.

[rcign]

Enlarge the fuel passages in the carb to twice the area..Use glow fuel...A G26 picks up 600 rpm with no other changes...