Have you any drawings , pictures , photos of such wonderous contrivances ? . 
Hello Mat!
We do not possess any inventions.
Everything was invented 50 years ago. Look carefully at the pictures of piston-engined airplanes of World War 2. There you will see a lot of interesting air intakes and diffusers. It is very individual for each individual aircraft, and for each individual form of the fuselage. You need to reduce the cross-section of the air window in front of the engine and increase the air purge immediately behind the engine near the exhaust manifold. This is your task as a model airplane. You have to come up with it and do it yourself. This is the whole point of our favorite sport.
Regards. Ruslan.
Ruslan - not to dispute anything you are saying, but you probably need to be aware of the fact that "no-nitro" fuel is almost never available, and even 5% is not that easy to find, without special-ordering it. 15 or 25% is the normal inexpensive fuel found at hobby shops.
In fact, the 40/46VF didn't need that much nitro, and most people ran 5 or 10%. It needs (for our purposes) less nitro than a PA, in general.
The PA75 (as used by David Fitzgerald) uses a very mild 10% fuel, even in hot weather. It's that way to make sure it runs in a very deep 4-stroke, all the time, at about 10200 RPM in the air (maybe 9300 on the ground) with a 13-4 3-blade prop. It also uses the *hottest* available plugs. I know that it has no serious operational issue running on 20% fuel nearly indefinitely, Of course it will run on 5% (I don't know about FAI fuel, I assume it will run OK) but with more critical handling required, touchy on the needle. It's still plenty strong enough.
It is set up that way to be competitive, which requires a tuned pipe, revs around 10500 in the air, and 3 3/4 - 4" of pitch. The 13-4 3-blade is nowhere near as much prop as it *could* swing (it works fine on my RO-Jett 61 with minor changes), but because the engine is so powerful, it's outstanding for purposes of propulsion but will still permit tight cornering.
Most of us would expect a 77 running a tuned pipe in this low-load condition would just be loafing along well within its capabilities, not self-destructing, just because you ran conventional fuel that we could consider very mild. I have seen/heard many of them running with no obvious detonation or sound of strain on 10 and 15% nitro, so it is extremely surprising to hear that will damage it.
Brett
Hello Brett!
Thank you for the very detailed description regarding the nitromethane issue. To be honest, I always find myself thinking that we are talking about completely different systems for assessing what we all call "proper engine operation."
For example, we have the normal operation of the engine Stalker 76 in mode
4 - horizon
in 4+ mode - when flying up
in mode 4 - - when flying down.
This means that the engine slightly adds up (but this is not mode 2), and when flying down, it slightly turns off relative to the flight horizon. ............. Now the most important thing: To completely destroy this flight mode of the engine and fly all the time in 4 + mode (where each subsequent dead loop is performed faster than the previous one), without dropping turns during flight down (without braking) - we need to add only 3 percent or more of nitromethane to the fuel. Stalker engines can work WELL without nitromethane.
If someone either works with Stalker or K77 for some reason, this does not mean that the engine works EXCELLENT.
Just for you it is acceptable.
If you like it so much, then please fly and enjoy your every flight.
I just expressed earlier my point of view and the point of view of all the test pilots of the Stalker company and the point of view of Oleg Korotchayev, the founder of the company and the manufacturer of the K77.
This is all that is written above - OUR COMMON OPINION.
And this opinion will not change. We have done all this long ago and tested hundreds and thousands of times.
Maybe we have a different quality nitromethane, or methanol?
Maybe we really just misunderstand each other because of the language barrier.
Regards.Ruslan
Hi Ruslan,
Hard anodizing the backplate certainly works, at least for a while, but that is not fixing the real problem. You should find out why the conrod wants to move backwards and make corrections in engine geometry.
-Is crankshaft flexing too much?
-How much is cylinder rake (angle compared to shaft)?
You can make small tricks afterwards, like grind a slight conicality to crankpin and play with cooling, but there seems to be bigger issues that should be solved.
I have learned that eliminating all unwanted sources of friction heat is one of the most crucial things if you want to increase the stability and life of an engine.
Besides, a (too) high rpm rarely causes catastrophic failures in healthy engines. L
Hello Lauri!
Thank you for your correct advice.
We three years ago tried all the options that you wrote. We optimized all the parameters and started to produce the K77 series only after numerous tests.
Everything worked fine and now everything works fine.
There are several failures that occurred through no fault of ours.
Two K77 were very overheated.
We simply call upon the owners of the K77 to be more careful with complex aircraft models. And this:
Monitor engine temperature after landing.
Use only recommended propellers and do not abuse nitromethane. If you do not do this - then the resource of your engine can significantly shorten.
If the pilots do not want to adhere to our recommendations, then follow the recommendations of top pilots who are trusted by many athletes.
Do not tune the K77 yourself if you do not know how to do it correctly.
Regards.Ruslan.
Topic: K77 Stunt Engine (Backplate) (Read 2226 times)