psgugrad, and others, great threat on fuel diy. Who is the Chicago area source for source for low cost methanol? $3 or $4 is a good price, I found 5 gallon pails for around $50 at a south side Archer Ave speed shop

Find an oil company locally for methanol. I buy methanol from a gas station for around $2.50-2.75 per gallon. 5$+ per gallon is outrageous. Methanol costs less than gasoline to produce.

Hi!
Nitro is not difficult to obtain here in Europé ,at least not here in Sweden.
I think most of us use at least 5% in our fuel (mix my own) as nitro makes most engines run more relible at idle and the top speed is more easy to set using nitro. There are eceptions with webra, SK, ASP and MVVS engines that run good without nitro but even those engines run better (more reliable) with 5% nitro. http://www.rcuniverse.com/forum/atta...mentid=2117209

In the US it is more common to use 10 to 20 % nitro. Engines sold in the US (not sure if that's on all of them) have usually a shimmed head to lower compression for higher nitro contend commonly used.
In our hobby store the glow fuel has a minimum of 10% nitro and the 15% version is just a dollar more per gallon ($24).
Nitro is probably cheaper in the US, thus the higher use.

I'm used to mixing my own fuel too, bu now there is a new law in sweden (and perhaps the rest of europe too) and you cannot buy pure nitro anymore unless you have a licence for competitions.

So we are mostly stuck with ready mixed fuels, with all synthetic oils, and no local shop to buy it from...

Points well taken on the nitro availability Europe, and other parts of the world. I've heard from numerous European flyers on this website who have asserted that practically no one in Europe uses nitro in their fuel and heard no one contradict such assertion... so I'm just going by what I've heard. I stand corrected.

As far as it's function is concerned, I stand by my belief that the main function of nitro is to make tuning easier. It DOES add power by adding oxygen to the combustion process, which enables the engine to burn more fuel. The ratio (by weight) of nitro to air going through a running engine is roughly 1.6:1. This is in sharp contrast to:

Methanol's 6:1 ratio
E85's 10:1 ratio
10% ethanol gasoline's (the BS we're practically forced to buy in the US, don't get me started on that subject) 14:1 ratio
Pure gasoline's 15:1 ratio

Since the engine can guzzle down more fuel containing nitro, the needle settings become somewhat less sensitive to their settings.

Nitro DOES allow a glow engine to make more power...by simply enabling the engine to burn more methanol by oxygenating the combustion process. You're getting more power by burning more fuel. No real magic or mystery there. One could obtain a similar power increase by going from, say, a .40 engine to a .46 engine (which may be made in the same size case) and burning cheaper nitro-free fuel.

Anyhow, I did see about a 500rpm drop in power when switching to nitro-free fuel in my ASP .46, something I hardly noticed at all in my 4 star 40. IMO most flyers (whether they realize it/would admit or not)would be more likely to notice that their engine is a bit easier to tune that they would that their engine is making a hair less power. Just my opinion. Peace

The main function of nitro is to make more power - end of story. That it helps in other areas is an extra benefit.

Whether you choose to believe that or not, is up to you.

Usually straight fuel at zero percent needs more compression and a hotter plug. We were forced to use it with FAI speed control line. It works fine but is more sensitive with pipes and throttling. I have read somewhere that 3% acetone mixed in will make the handling a bit better. Not more power, but better transition. The old Rossis that we ran had a bowl type head shape for high nitro, and a trumpet type for FAI fuel.

I'll chose not to, and thanks for your kindly allowing me to do so. Here's a simple thought process I'll take you through to demonstrate why:

Imagine, all other factors being equal (which they usually are not, but just for illustration purposes), switching from 0% to 10% fuel increases your engine's rpm from 12,000 to 13,000. That's an 8.3% increase in RPM. Now factor in the fact that as a prop spins faster, diminishing returns kick in...this means that in this example the 8.3% increase in rpm will not result in an 8.3% increase in thrust being generated by your engine-propeller combination (ask any mechanical or aeronautical engineer if you don't believe me). I don' know exactly how much the difference would be, but I know it would be something significantly less than 8.3%. Are there more flyers who would notice that the nitro makes their engine easier to tune, or are there more who would notice something along the lines of a 5% increase in thrust? I would guess the former by a wide margin.

There's no need for us to argue semantics, but your assertion that it's the "end of the story" that nitro's main function is to increase power is akin to asserting that it's the "end of the story" that the main function of beer to enable one to get intoxicated. Drinking enough will certainly do that, but some people just want to have a few with a pizza. In other words, it's not the "end of the story" at all. It's simply your opinion.

Hi there drac , where u getting the nitro from at that price ? The cheapest I can get is nearly x2 that price here in Adelaide . Cheers the pope

Melbourne. If I have to freight it, then it costs $15. But there are ways around that:D

If you hardly notice the difference in 500 RPM then I can understand your pessimism. However to me 300 RPM is a huge difference and the only reason I would use 25% or more nitro. Engine becomes easy to tune with just 5% nitro. And the difference is greater than a .40 to .46 more like a .40 to .52. But If I had a .52 I probably would want it to perform like a .74 at times, depending on the plane and its use.

I've never noted more than a 200-300rpm change in rpm for every 5% nitro I add to the fuel. Keep in mind the combustion chamber shape has a lot to do with how an engine responds to nitromethane. AFAIK, European engines (including many ASP models) are designed for low nitro (usually 5% max) so using no nitro at all won't show such a power deficit using FAI type fuels whereas engines designed to use more nitro (OS for example) will show a higher power deficit when not using nitro. Increasing the compression ratio and changing the combustion chamber shape can regain some lost power when not using nitro but if the engine doesn't use a button head, you'd have to make a whole new head which for most folks isn't easy or cheap to do.

You would think that the velocity of the air would increase in proportion to the RPM but actually it does not. Also consider that the resistance of the blade will increase by the square of the velocity so that HP actually is much higher than 8% in your case. I ran this though a propeller calculator and the thrust was about 20% higher for your 8% increase in RPM. Now we have started another discussion I guess.

So nitro was invented primarily to make the tuning of RC engines easier? Interesting theory.

Nitro helps increasing the power to weight ratio and makes an engine easier to tune.
Why fight about it? Maybe we can get the inventor of nitromethane to chime in here, can't we :cool:
I guess we all like the idea of saving some $ on fuel, that is what the discussion was about.

Weather is great around here, if you don't use your planes, your engines will gum up, with or with or without nitro.
Yes, I always forget using after run oil.

As I understand it, some of the other uses for nitromethane are stabilizing dry cleaning chemicals, solvents, pharmaceuticals, and a myriad of other things besides fuel. I doubt top fuel dragsters use nitromethane to make tuning their engines easier.

This is why I never left glow ...

http://www.rcuniverse.com/forum/atta...mentid=2117672

Too many people are losing their homes and garages due to lipo batteries.

Looks like the charger blew up. I was thinking about buying a multi port charger.
Do you know why ?

I am very surprised that no one knows why nitro was invented!

A John Force Burnout of course!

http://www.rcuniverse.com/forum/atta...mentid=2117721

It probably wasn't invented to make a toy airplane faster :p
And I am not sure why but I am glad someone did it :)

I just add my thoughts about going back to methanol powered engines.
- My fuel is 5-10% nitro with 20% castor and the balance methanol
- For me 50% of the hobby is the fun I have while running tiny engines. No need to run bigger, not so tiny gas engines.
- Methanol engines seemed to be the main problem for 80% of all RC modellers. Now they change to electric which makes every methanol engine a novelty and every owner of a good running methanol engine becomes a rocket engineer in their eyes.
- My wife doesn't need to be jealous when I come back home and smell like a fryer due to the castor oil.

I'm a little confused. Are you talking about HP or thrust? I could see where an engine going from 12000 rpm to 13000 rpm would be putting out more than 8% more HP due to air resistance on the blades...analogous to the fact that it takes much more than 10% more HP for a car to go 88 mph vs 80 mph. Bugatti makes a $1.5 million supercar called the Veyron with 1000 hp and a top speed of 253mph. In an interview, the car's lead engineer stated that the slippery car needs "only" about 500 hp for the first 215mph. The other 500 hp is needed to get the car from 215 to 253.

What I don't understand is how you came up with 20% more thrust from an 8% increase in RPM. The engine might be producing 20% more HP to obtain the 8% increase in rpm, but the increase in thrust wouldn't be anywhere near 20%. It wouldn't even be 8%...I don't know what the exact number would be due to the many variables involved, but the increase in thrust would always be less than 8%.

I don't know what kind of planes you fly, but if you notice a 300 rpm difference, you're a better pilot that me. (don't get a big head...that isn't saying much. HA!)

Funny that you mentioned ASP (Sanye I believe they are called outside the USA) A couple of years ago, I bought one and was impressed so I bought a few more. I have a .28 a .36 a .46 a .61 and a .91. They have all proven to be gems that run great on the cheap fuel I brew. Tight compression seems to be one of the keys

I bought the .46 about 2 years ago when my old OS 46fx got soft on power. The nickel liner peeled and Tower wanted $75 for a new piston-sleeve. For less than $60 I got the ASP .46 and OS has lost a customer, likely forever.