Okay, what about if we level the playing field and talk about FAI fuel, and remove the nitromethane additive.

Or on the other hand talk about adding nitropropane to petrol?


While the 160fx is a good candidate for conversion ( the MVVS 160 had enough power to pull my 2m Haya-Ji through a knife edge loop, so I think it would have got me to masters, however the haya-ji was a slippery airframe) it still has the dubious quality (for a petrol engine) of having port sizing, and port timing suited to glow. Not to mention the fact that the con-rod really needs to be needle rollered, and in my experience on the 160, this puts a lot of stress on the needle rollers of the bing end, to fit into a conrod that will fit into the existing crankcase.

This is, to me like taking a toyota landcruiser around lemans, not particularly suitable for our needs.


I think the only way that we're going to get a competitive petrol engine, is to design a DEDICATED, petrol burning monster from the ground up with F3A soley in mind.

I did read that webpage and yes it is a very simple conclusion.

Modern pump gasoline is not in fact strictly Octane (C8H18), but is actually a mixture of hydrocarbons between C4H10 and C12H26 or so, plus other additives. Ethanol (C2H5OH) is present at a 10% in most of the US.

Oxygenated fuels (added hydrocarbon molecules containing an oxygen, typically an alcohol like ethanol) are more important in automobiles where we are held to running leaner settings for emission purposes, and the oxygenated fuels raise the octane rating a bit to allow running leaner without detonating.

The vast majority of oxygen available for use in combustion is from the atmosphere, and not from the molecule itself. The oxygen molecule available on the methanol is a very slight contributor to the combustion process itself. On top of that in a gasoline engine there is significantly more (2.5 times more) available air in the combustion chamber per stroke than with a methanol engine.

All that said, much work remains to be accomplished before gasoline is truly a viable power source for pattern. Your results on the Abbra prove that!


I still believe it can happen with a larger displacement engine, but the problem is those get so HEAVY it isn't worth the effort. A Moki 2.10 would be a good candidate due to its beefy crank and conn rod but it starts out at 42 oz or so, quite a bit more than even a 1.70dz.

No real reason this couldn't be done. A DA150 puts out a terrific amount of power on canister mufflers. A well thought out design would weigh considerably less than the typical 40% IMAC plane.

Props are not really available for pattern type performance though. You'd have to carve you own which isn't a big deal actually. Something with around 18" of pitch should work very nicely at the lower rpm of the 150. But it would need to be crafted properly to do any good

BTW, a few months ago I watched a video of an electrified 40% IMAC plane which was using a conventional wood prop of appropriate size to drive the crate. It sounded about as noisy as the gas powered counterpart...that's how bad some large props are. That much noise requires a lot of power to generate

Another BTW, Ed Alt, Frank Imbriaco and I have been discussing the Syssa 30 cc gas engine. We will try to get to their shop in the next few weeks and bring a few pattern props with us. We will also bring the ES 40G pipe along and play a bit. We'll report in the KFactor probably. Having had considerable experience running Moki 30cc on glow, (and OS and Webra) it will be interesting to see how the engines compare.

I have a project going right now and have planned to use the ZDZ40RE F3A engine in it. If the Syssa 30 cc works well, I may reconsider the powerplant. The weight savings is substantial. The ZDZ has superb manners however....the Syssa has alot to live up to

MattK

i don't wish to damage my airframe by installing a screaming gas engine in it i have see people & don't wish to do this they are very far from glow & electric power leave them for Giant scale & 3D fliers.....................i can t compare any gas engine to a glow engine.....................PEACE PLEASE.................

Another option is offered by a new Mintor 37cc gas engine: 35oz without ignition and muffler/pipe, 24lbs of thrust on a 20x8, 20x10 prop. See http://www.mintor.net/pagine/37cc.htm

It smell in the car!!!!!

I see that they replaced their own design carburator with a Wabro carburator. That is a good move. I tried the Mintor 110 cc for IMAC 3 years ago and didn't work at all. I recomended to use the Wabro and looks like they decided to do it. Someone needs to try this motor in pattern.

Vicente "Vince" Bortone

Yes, apparently they replaced their own design carburetors with Walbros on the entire line of engines. There is a link to videos made by Mintor users: http://www.mintor.net/pagine/video-cl.html#topgallery. From the videos one can get some idea as to size, vibration, power, and smoothness through the whole rpm range. However, there is no pattern plane video yet.

Soft mounting and tuned exhaust are the order of the day, just like with glow. This is no big deal. Somewhere in this website I have a thread describing how to make your own soft mount. Very lightweight and works great. Look it up.

On the other hand, it requires that you know how to build models, not just assembling and packing equipment into ARFies. If you know building, then it is simple enough to do.

BTW, the same mount design has been in my Temptress 2x2 since 2003, or at least 1500 flights. Every servo is original and has never been re-built.....the doubled rubber simply works great

MattK

As has been with their glow engines, beautifully done. I just hope the gas offering works better then their glow stuff. Is there a price yet? And delivery?

MattK

Gas engines can be used for pattern, but they are not going to be competitive, that's the problem, there is no way gas can compete against top glow or top electric engines/motors in AMA Masters or FAI.
To be competitive cost money, at least for know.

Absolute statements like this one just make me more determined than ever to complete my latest design and get it flying for next season. Planning on the ZDZ40RE F3A w/ tuned exhaust. I guess I have to show you the way. The trick isn't so much the design and gas power....

For me, it's the trying to design in enough lightness and simplicity so that average builders can do the same thing. I have threads on both the soft mount and the wing techniques I used. I may start one on the prop mods I am making. Wood composite props are not only much lighter than the plastic stuff, they are far stiffer.

MattK

There is no place for a tuned two-stroke in competitive F3A any more. It is not about the power level but more the propulsive/drive characteristic that does not fit.

With proper cooling the Saito works.

BTW, the same mount design has been in my Temptress 2x2 since 2003, or at least 1500 flights. Every servo is original and has never been re-built.....the doubled rubber simply works great

Six years are 2190days and you got 1500 flights?? I envy you....................

What class do you fly?

The Mintor 37cc has been available for almost two years now. In fact the majority of videos on the www.mintor.net concern this engine. The distributor of Mintor gas engines in the US is Dietrich Performance at www.dietrichaircraft.com. However, the smallest Mintor he lists is the Mintor 55cc for $595. It's worth sending him an email.

Save your money... even though it says F3A on the box, it's about as far away as one could get. It's just a slightly lighten version of the original, unfortunatly, the lightening creates a great deal of vibration... guess where they took the weight from? yeap, that's right, the counter balance. The engine hasn't been designed with any dedicated muffler pipe or soft mount in mind, leaving you and many before you to do the experimenting. It's should bereported to the Trade Discription Authorities.Needless to say, this motor isn't available from the factory in Europe. It's a local hatchet job.

SportF3AAMAMasters. You should never envy anyone.

MattK