Nitro fuel

[helijohn]

I realise it a horses for courses thing and down to personal taste but I see on US forums that 30% seems to be the norm so what in general do you use. I'm thinking of 30 size birds so OS 32/37s etc. but generally is interesting as well.

[Sburv]

20% Opti for me.

I think most have settled on using 20% being a good compromise on cost and overall performance.

[nobbycopter]

I use 20% Opti in my OS32 in my Raptor 30 (and in my OS91 in my 700)....perfectly fine for my style of flying

[trillian]

I think it depends on a few things. The smaller engines can really use the extra power you get from higher nitro, but if you're not doing any aerobatic type stuff then it may not be worth the expense (although, those engines are quite economical anyway).

When I was running an OS37 it really seemed to run best on 20% and above.

Now everything I have is .50 or larger and I have been using mostly Rapicon 15% for the last few years. I have tried a bit of Model Technics 20% and saw very little difference in performance.

I also sometimes use the Model Technics Bekra 16% because one of our club members buys in bulk and can get a good price on it.

[pchristy]

You can't just consider nitro on its own. A lot depends on the design of the engine as well. I have several engines that simply refuse to run properly at the slightest whiff of nitro, yet they run like turbines on straight!

Super-Tigres are one case in point, but also I have a GSM 25 that gets very hot and spitty if there is any nitro present at all. The same applied to an AirSupply 40 I used to have - and that was a Japanese engine! It would outperform an Irvine 39 when it was fed with the right fuel - straight!

Nitro is cheap in the US compared to here. Also lots of States have "hot and high" conditions, where nitro is essential to restore the performance that would otherwise be lost. Here in the UK, we are mostly just above sea-level, with a cool climate. Some engines may benefit at tickover from small amounts of nitro, but any power increase will follow the law of diminishing returns: The first 10% may give you a 10% power increase, but the next 10% will only give you 5% increase!

The most I ever use is 16% (for the OS's I have). If you are flying competitively, it may be worth going to 20%, but there is absolutely no point in going any further here in the UK. It will just empty your pockets quicker, and knacker your bearings quicker, too!