The fashion for nitro

[David perry 1]

Ive always been puzzled...back when i started out the use of nitro was exotic...maybe 5pc for high days andnholidays and 10pc for high end contesters and americans, but it seems 10pc is norm and 12 to 20pc barely raises eyebrows.

 

Why?

 

Are we just richer than our forebears? Or just more liberal with the stuff in the same way that a .60 sized engine was large amd the club average was a .40.?

Edited May 12, 2023 by David perry 1

[Jon H]

I think it was driven by the US market, who want power...power, maybe a little more power? Very often they build their models like they build their cars. Fit a 200 size engine in a 60 inch warbird designed for a 90, which should weigh 9-10lbs but for some reason weighs 17. They then fly them at 200mph actual speed because its 'awesome'. I personally would replace awesome with stupid, but that's me. 

 

So anyway, engine manufacturers, saito especially, gave them what they wanted with higher power to weight ratio engines and recommended more and more nitro to get the power and keep the engines happy with their new more aggressively tuned designs. OS then had to up their nitro recommendation to keep up, as indeed did Laser as we went from 0 to 5, although there is more to it than just power in our case. 

 

There is also this piece of modelling folklore that higher nitro will improve reliability, and this simply is not true. Installing, tuning and cooling the engine correctly will improve reliability. 

 

So that is my 2 cents on it. Most engines would run fine on no nitro, 5 gets you most of the advantages with no real disadvantages, beyond that the disadvantages begin to mount and fuel consumption/fuel cost rises really fast above 5%. 

[Nigel R]

New news to me, I use 5% because it doesn't rot bearings.

 

Almost nobody in my club flies anything above 60 size. In fact most fly small stuff and electric at that.

 

Maybe my club is stuck in a timewarp?

[Nigel R]

5 minutes ago, Jon - Laser Engines said:

Very often they build their models like they build their cars

 

In all fairness to any Americans involved and the American market, American cars don't have an excess of power and weight, they're simply larger than the typical European market models.

 

[David perry 1]

Jon, i agree 100pc and your comments ref the american influence are what i suspected.  Its all expensive nonsense in the end.  

 

Times change though.

 

Nigel R...yes it is  ha ha.  Maybe not.  Im sure most modellers are limited to car size but the numbe of large models is far far greater now.  

[Cuban8]

43 minutes ago, Nigel R said:

 

In all fairness to any Americans involved and the American market, American cars don't have an excess of power and weight, they're simply larger than the typical European market models.

 

Judging by what one sees on modern US TV shows, their cars for urban use don't look that much different to what you might see in any UK town. Certainly, they still do go for the huge SUV, or whatever they're called, types more than we do. Still, with US petrol (gas) being sold for 1/3 of what we are being charged per litre (just Googled it) you can understand their on-going love for them.

There'd be another American revolution if their government tried it on with fuel prices as our lot (of any colour) do.

Used to use 10% nitro in all my fourstrokes up to twenty years ago, for no other reason than that was what most others were doing. Reduced to 5% and haven't noticed any difference at all in performance - a lot cheaper though.

[Engine Doctor]

Is it all down to American influence ? Brits have grown into a " must have the latest model / fashion " culture a bit like the "King new suit of clothes" that Danny Kaye sang back in the 50's. Just look at car registrations and the rush to get the new reg to show off your the neighbours. And how many rushed to buy the must have latest reg EV spending thousands to get cheaper fill ups  now regret it ? We do it with everthing clothes cars tech etc. 

Large models were flown at shows to wow the crowds and then the better off club members thought ill have one of those down the club field.

How many clubs have lost their flying site not just through the noise that these bigger planes needed but due to being flown a lot further away and far too near to surrounding properties as flyers of big models often do ? 

A similar thing has happened with jet turbines as they eat up air space and locals then complain. 

Us Brits can be just as foolish as the Americans when it comes to our toys and the latest "Must have".

[Jon H]

1 hour ago, Nigel R said:

 

In all fairness to any Americans involved and the American market, American cars don't have an excess of power and weight, they're simply larger than the typical European market models.

 

 

Its a sterotype that US modellers build heavy and i have joked with many of my customers out there as it is an accurate stereotype at many clubs. 

 

In any case, the herd mentality and keeping up with everyone else is the crux of what i was getting at. If the US modeller wanted X and Saito gave it to them, other manufacturers had to go along with it to remain competitive. As the products sold out there were the same as the products here, we inherited the same thinking almost my accident. The proliferation of forums and youtube probably contributed to the spread of the high nitro mentality across the pond so modellers here drift towards it. Retailers too have a small part to play as certain well known 10% nitro fuel had a favourable margin on it vs 5%, and the customer used more of it so would be back more often. Recommending the 10% over 5% was marginally better for business. 

 

One small caveat here. High nitro is not a problem in itself. Nitro cars, boats, heli's, ducted fan etc may require it because of their specific use case and this has always been so. I think cox engines used to use about 16% (correct me if im wrong) because of their small size. So its more the blanket use that is new i would say. 

[J D 8]

                   You are right that Cox like high nitro but have found even they are happy on much less than the 20% plus that used to be recommended by some. Mine run on 15% car/buggy fuel.

[Cuban8]

Some interesting info here.......https://coxengines.ca/public/files/FG.pdf

 

I remember having a Cox Baby Bee when I was about 10 years of age and was sold Keil Kraft Nitrex 15 as a suitable fuel. Remember the disapointment of not being able to get the engine to run well no matter what I did. Clearly, insufficient nitro content judging by Cox's data sheet.

Nobody to help me - my dad could build you a wonderful brick wall, lay a driveway or knock down your old rotten ceilings and replace them with skimmed plaster board etc but model making really wasn't his thing. Always encouraged me though and bought me what I wanted, within reason, but usually meant waiting for birthdays or Christmas.

[Chris Freeman 3]

I normally used ST motors that used 5% nitro for the smaller stuff and 0% for the larger motors. I have found that the OS and Saito  FS motors need around 15% nitro to run well and even the OS 2 strokes run better on more than 5% nitro. Motors made for the American market had to perform on higher nitro fuels. I recently bought a Sig Bravo with a ST 3000 in it as the owner said he could not get the motor to run reliably and even tried 15% nitro to get it to idle. He was shocked to hear that it was running very well with no nitro and 12% oil.

 

A while back I was given some fuel that a Japanese Aerobatic team had used at a World Championship event and I am not sure what the mix is but I did add some additional oil just to make sure there was enough. My four stokes do perform much better when it is used so it must have a high nitro content.

 

The one thing that nitro does not cure is the setting up of the motor as you do still have to do it right.   

[Jon H]

47 minutes ago, Chris Freeman 3 said:

I have found that the OS and Saito  FS motors need around 15% nitro to run well

 

I have never found this myself, but i see this sort of comment often. It would be interesting to understand the reasons for the different experiences with the same engines. I currently fly an OS FS40, FF240 and saito 45 on 5% without any problems

[Nigel R]

1 hour ago, Cuban8 said:

their cars for urban use don't look that much different to what you might see in any UK town

 

In some cases the exact same car. I'm currently driving a Buick Regal (Vauxhall Insignia).

 

 

 

[Nigel R]

4 minutes ago, Jon - Laser Engines said:

OS

 

Mine are happy with 5%.

[Chris Freeman 3]

They do run on lower nitro fuel but there is a big difference in performance with the higher nitro fuel. I found that the Saito twins are much better on about 15% nitro. I never used to mix my fuel with more than 10% nitro but the Saito 180dp twin is much better on 15%. I

[Chris Freeman 3]

Just a thought as well is that I am in Johannesburg in South Africa which is 5500 feet above sea level so that could be part of the reasons for better performance with the nitro.  

[David perry 1]

5000 ft is considered 75pc power in full size piston aviation.  Full throttle only gives 75pc power, so yes, nitro might help.

[Jon H]

40 minutes ago, Chris Freeman 3 said:

I am in Johannesburg in South Africa which is 5500 feet

 

ahh there we go. 

[J D 8]

       I recon American's who love their motorsport got into the "nitro" thing from top fuel dragster racing. 

Special engine's of 8.7ltr[built very strong] burn a mix of 90% nitromethane and just 10% methanol at a tremendous rate. It is still the methanol that provides the power but it is the nitro that allows the fuel to burn at so fast a rate. A top fuel dragster will use 15 to 20 gallons just warming up!

  Engines can develop as much as 11 000 horsepower and propel the dragster to 100mph in less than a second, toping out just a few seconds later at over 300mph!

    Those who have moved to a lower nitro fuel will notice they often have to turn the needle in some as the engine runs richer now that it is getting more of the fuel/methanol that actually is the power source.

 

[David perry 1]

Wow

  If i were clever id calculate the g imposed on the driver!   

 

Thats a lot of expensive fuel too.

[Philip Lewis 3]

3 hours ago, Chris Freeman 3 said:

A while back I was given some fuel that a Japanese Aerobatic team had used at a World Championship event and I am not sure what the mix is but I did add some additional oil just to make sure there was enough. My four stokes do perform much better when it is used so it must have a high nitro content.

Highly likely to be 30% as that is what the YS 170's use.

[John Stainforth]

I think there is a lot of anti-American sentiment being expressed here that is not well-founded. Having been in a southern US model club and several UK clubs, I would say that the general competence level in the US club was very high and that we, in the UK, could actually learn quite a lot from them in practically all areas, from club organisation, to safety and to model flying and set up. All the senior members of the US club were very fussy about the set-up of their models, such as fuel mixes and prop sizes. There are several differences between US and UK clubs; here I am generalising. Generally, the weather in the southern US allows vastly more flying time than the UK, the temperatures are way hotter and the humidity higher, and the noise restrictions less. In 2010, I brought a bunch of planes over from the US to the UK and was very surprised how much less well they seemed to perform here. Several factors were at play: (1) the altitude, (2) the fussier noise restrictions, and (3) the lousy fuel I bought here. The last item I changed out for another brand with similar specifications and the difference was like chalk and cheese - I suspected the first batch of fuel had nowhere near the nitro content stated, and probably none at all (that's when I started weighing and doing volumetrics on the fuel I was buying here to check the nitro content). The altitude and air temperature/humidity difference between here and the US club also made a surprisingly big difference - one that was hard to justify theoretically. I found I could partly correct for that by changing prop sizes by an inch or so. Finally, the US club was not so fussy about the noise limit (there was an enormous shooting club next door, that made such I racket you'd think WWIII had started there, which drowned out the noise of model planes). So everyone took the baffles out of their silencers, which probably gave about 10% more power - and may be one of the reasons why higher nitro fuels worked better there. I personally did lots of tests on different nitro fuels and found my Saito 4-strokes and OS 2-strokes definitely ran better and more powerfully on the higher nitro (12 to 15%) fuels. Another thing that surprised me was that I did not find the higher nitro fuels were more expensive to run; the opposite in fact: they seemed to be very economic. This was a bit baffling, but I think it was because the engines ran at greater power at given throttle settings, so I was probably throttling back more with the higher nitro fuels. 

[David perry 1]

Not sure theres ANY anti american sentiment expressed here but folks see what they  want to  see.  The US and the British environments are different in myriad ways and similar ditto.  Im sure it must affect how and what we fly.  

[Simon Chaddock]

A very long time ago I bought some Cox "performance" glow fuel for my Tee Dee 020 from the local model shop.

That was 30 % nitro!

It didn't half make the Tee Dee scream, 32,000 rpm claimed.

 

[David perry 1]

15 minutes ago, Simon Chaddock said:

A very long time ago I bought some Cox "performance" glow fuel for my Tee Dee 020 from the local model shop.

That was 30 % nitro!

It didn't half make the Tee Dee scream, 32,000 rpm claimed.

 

Ha ha i can actually hear that right now!!!