Nitro Percentage

[korzry]

I've just finished my first gallon of fuel in my Raptor 30. I was running Magnum Heli Plus fuel. They hobby shop didn't have anymore of the same stuff, so I bought Magnum Heli 12% fuel. With the new fuel I hardly had any power it the same mixture settings. I leaned out the engine some more to increase the engine rpm to where it was the the previous fuel. Is this okay to do and is the proper thing to do. Also, what are the pros/cons of diffent types of heli fuel?

[GWRIGHT]

If you drop the nitro percentage you must lean the mixture, if you raise the nitro percentage, you must richen the mixture. If it's hot you need to lean the mixture (less density, less air,..so you must have less fuel to maintain proper mixture), if it gets cold, you must richen the mixture. You were probably running a higher nitro content, or a fuel with a higher viscosity (it would flow slower), thus the new fuel (lower nitro, or lower viscosity) needs the needle leaned. There is a trait in any combustible product that, as I understand it,.. tells you the proper ratio of that fuel compent and air for the most efficient combustion. I'm not a chemist,..that's just how it's been explained to me :) . The stoichiometric value for methanol is around 4 to 1 (4 parts air, one part methanol), the stoichiometric value for nitromethane is about 1.6 to 1 (1 part air, 1.6 parts nitromethane), so you can see, as the nitro percentage goes up,.. you need more fuel and less air,..hence the required leaning of the mixture with your lower nitro (i'm assuming,..could also be lower viscosityfuel).

[DanC]

I have just gone done a similar thing and it is worrying to me about the amount I have had to lean off of the mixture.

I run a raptor 30 with an OS ringed motor plus zimerman pipe

I tried a model technics superglo 10 to start with from http://www.modeltechnics.com/ and used two gallons of it.

Its basically 10% nitromethane 70% methanol and it ran fine with out ever missing a beat. The needle value was about 1 1/4 turns from fully closed

I was very happy with the way the engine ran but at 17 quid an imperial gallon was not exactly over the moon about the cost

But I have tried another fuel recommended by a different model shop than the one I normally go to (I was in a rush and it was nearby) and I was told there its only those with more money than sense run 10%, none in the local club to the shop run nitro in their helicopters, they all run straight fuel and this will do

THe fuel I have now got is dynaglow straight eg 90% methanol and cost 9 quid a gallon and I have had to re-adjust the needle value till its about 3/4 of a turn from closed to get anything like I had before but the slow running throttle responses are very poor and stalls on the same amount of throttle for tick over I had before.

What concerns me is lack of volume of lubricant and I feel I have been given a bums steer towards a slow selling item, now I am away from the shop. God I hate glow motors but love the power and the ability to fly models like a raptor at a reasonable price

[donlynn]

Gidday
I too am running a new r30 tt36 stock std

I run 5% nitro 5% castor and 15% coolpower blue.

I've burnt 25 tanks and it goes sweet as,maybe I'm not doing something right but it runs like a clock, comes onto power nicely after idle. stock carb has DV-11 on it.

Regards Don