I just inherited a gallon of Tower Power 35% nitro heli fuel. I'm thinking that it should be good for my Cox and Norvel engines. Tower keeps it a mystery as to the castor content but by all indications it is 18% oil split between castor and synthetic. What do you think?


John

I think you can use this with no worries so long as you add only castor to up the lube. Cox engines love castor! As for the Norvel, the extra castor can do no harm either.

Robert

i have run it before. just added castor. ran great . no problems.

Minnesotamodeler is pretty close. If starting with 18% oil and you want 22% oil by pouring out some fuel and adding castor, you need to add 6.24 oz. Call it 6 1/4 oz.

You start with a known amt of oil in your gallon of fuel.

You pour out an unknown amt.  (X).

You pour in this same amt (volume) of pure castor, to get to 22%.

So:  .18(128) -.18X + X = .22(128).

X solves as 6.24 oz.

Currell

Well, the oil doesn't burn (mostly anyhow) but it does dilute the mixture, so overall percentages of nitro and methane both drop a little, but yes, the ratio between the two remains unchanged.  I think.  Makes my head hurt.

If it runs OK and doesn't harm the engine I'm happy.

A lot of the car guys ( especially novice) run high nitro / low oil and lean the needle to a screaming/ rod breaking/ piston burning/ bearing killing /maximum RPM.

This delights the high volume / flashy ad type dealer who earn very little actual profit on the initial package deal of car / engine / radio, but make up for it in spare parts, engines, upgrades, high nitro fuel in quarts, etc.

Watched the record holer at one at the NATS.  He would assemble an engine an run.  It sounded like a high speed Dremel.  Tear it down and do something to it.  Reassemble it and run it again.  He put it in the plane and made one flight.  Tore the engine down again to start doing thing to it again.  I think he rebuilt the engine a dozen times to get maybe three flights.  DOC Holliday

With adequate oil, the limit on engine life is usually dirt.  Cox, of course ran all castor during the "good" times.  They ran a test on a Tee Dee .049 to evaluate life.  In a clean environment, the engine ran 400 hours (not 4, not 40, 400!).  At that point, it needed an electric starter to get going, but would still run!  Duke Fox ran a similar test on a stunt 35 and gave up after using up a 55 gallon barrel of fuel.

Nitro/methanol determines the run and power, oil then only affects the fuel consumption and needle setting (both of which CAN be important).  More oil means more open needle and less fuel draw, plus more fuel consumption as the oil does not contribute to the power.  However, the cooling and life improvements balance out somewhere.  As usual, you have to hit your own best result.

After (finally) reading the break in instructions for the AP Wasp, I broke it in on 28% oil fuel, and am currently running 24%.  The one with the Tee Dee .049 venturi turns 23,500 on an APC 6x2 prop, and flies 3.6 second laps on 45' eyelet to eyelet lines.  I don't, however, have enough fuel capacity in that plane to finish the pattern.  Trade-offs, trade-offs!  I will switch that engine to the more recent Sky Sport (3/4" longer tank compartment) and cut the oil down to my more usual 22%.

I will soon get back to baggie tank development, I have been trying to assure that I have at least one totally competitive plane for the next meet.  Antone Kephart won 1cc and took home the "Leprechaun Pot o' Gold" trophy at the Palmer Memorial Meet with about 460 points with a 1/2A Magician from Flying Models plans.  Antone let me fly the plane this weekend, and it is as good as I remember the original.  Smooth, crisp turns with minimum overshoot (he is still tuning it in) and rock solid line tension.  Plenty of maneuvering room to allow true vertical eights (the toughest test, in my book, you can cheat everything else).

Supposedly, Brodak is going to produce a Baby Magician.  I have no idea how good it will turn out to be.  Until then, get the plans from FM and call Eric Rule for a set of laser cut ribs.  My version is an accurate reproduction at just the right size for competition .

I did get the Bambi running.  The crankcase/crankshaft lengths were mismatched and it was binding.  Lathes are a wonderful thing, so I was able to make a correction.  It actuall produces a breeze on a Cox 4.5x2 prop!  I had heard rumors that it just produced enough wind to keep from overheating, with nothing left over for flight.  I think I may put it in a Speedy-Built replica model for flying on .006 lines.  With modern RC equipment, it could easily fly a plane, but outdoors, it would probably blow away downwind, and I don't think the indoor RC site I frequent would appreciate the drips and smell!