stunthanger.com
Engine basics => Engine set up tips => Topic started by: David Ruff on September 07, 2016, 05:20:23 PM
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Seriously.
I am reading that they have metal shavings and probably should be taken apart and cleaned before running.
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Pull the back plate and flush it out with some kerosene then.
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thanks, Chris. Sounds like the way to go.
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Hi, Dave - I developed the first Aviastar 53 for CL use.
I have attached an article that I wrote about it.
You can read Tom Weedman's evaluation.
It's really a fine engine but if not equipped with the mods shown in the article, you MUST perform them for satisfactory stunt runs.
Bob Z.
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Thanks, Bob. Appreciate the great info.
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Hi, Dave - I developed the first Aviastar 53 for CL use.
I have attached an article that I wrote about it.
You can read Tom Weedman's evaluation.
It's really a fine engine but if not equipped with the mods shown in the article, you MUST perform them for satisfactory stunt runs.
How did it work with conventional stunt props, like a 13-4 in a constant 2-stroke? Or rather, what was wrong with it stock. It appears you started with lots of pitch, then went up. That will force you into very low revs.
Brett
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My first tests were with the stock engine and a Top Flite 13-6 wood.
It made marginal power.
I then bored out the venturi and that helped greatly but no matter what I tried, extra head shims, etc, it would run away. Could not get a decent 4-2-4 run and the runs were erratic.
Shortening the venturi by 1/16 inch increments helped and I shortened it to the length of my Super Tiger 60 venturi.
It mellowed a bit but still ran away.
Creating the larger combustion chamber and angled squish band did the trick. It ran just like my Tiger 60.
At that point, I gave the engine to Tom and let him play with it.
He really liked the engine. as far as I know, he still has it.
Bob Z.
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My first tests were with the stock engine and a Top Flite 13-6 wood.
It made marginal power.
I then bored out the venturi and that helped greatly but no matter what I tried, extra head shims, etc, it would run away. Could not get a decent 4-2-4 run and the runs were erratic.
Shortening the venturi by 1/16 inch increments helped and I shortened it to the length of my Super Tiger 60 venturi.
It mellowed a bit but still ran away.
Creating the larger combustion chamber and angled squish band did the trick. It ran just like my Tiger 60.
At that point, I gave the engine to Tom and let him play with it.
He really liked the engine. as far as I know, he still has it.
I would be interested to know if it worked if you tried a more conventional prop and permitted it to rev up. A 13-6 hasn't been a mainstream stunt prop for about 30 years now. The reason I am asking, of course, is that it may well run really well stock if you ran it at a normal speeds. You would certainly get better performance with 4" or so of pitch if you can get it to work, and also maybe find that that it works without modifications. I don't know if it would, but you didn't really even try it.
Brett
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You are correct - I didn't even try it. ::) ::)
Since I no longer have the engine, I never will. n~
I got the run to where I wanted it - I was looking for a 4-2-4 run and that's what I my modifications yielded.
The guy I worked for was satisfied and and many people that bought the engine loved it.
My job was done.
If you're really interested in how it performs stock, track the engine down, find an original head and give it a try.
Bob Z.
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Brett, (and I hate talking over someone else) but it seems that the benchmark here was to 'be' the Tigre 60, rather than being the Aviastar - if you get my meaning.
Everything points to getting that 13x6 to run in a 4/2 break rather than getting the engine 'as is' suitable for stunt.
And that's fine as I am sure that old Tigre style run is still loved by many, and (as you are angling here) its not the only way to skin a cat.
The quote of "the mods shown in the article, you MUST perform them for satisfactory stunt runs," seems a bit limiting.
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You are correct - I didn't even try it. ::) ::)
Since I no longer have the engine, I never will. n~
If you're really interested in how it performs stock, track the engine down, find an original head and give it a try.
I wasn't trying to pick on you about it. But, you have to admit, it's hard to declare modifications mandatory with great authority, when you never even tried in a conventional way.
Of course, I have no idea if the engine can be made to run in any useful way, but it would be very unexpected if it ran stock the way you were trying it.
Brett
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I think I still have all 3 sizes of the Aviastars and although I never tried to make them into ST 60 type runs, they seem to run well with the proper size venturie and a 12x4 to 13x4.5 prop, 22% oil synthetic/castor blend, T Bolt RC long or Glow devil 300 plug, I used the Aero Ultralight tube mufflers I used to sell on all of them .The old Bolly 12.5 x 5 worked very well too
Randy
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Chris - you're 100% correct. I probably could have done more experimenting but:
1) I did not have the time
2) I did not have the ambition
3) I was seeking a goal that was requested by the distributor/retailer of the engines.
Remember, this was a production RC engine - not a purpose built unit like a Rojett.
If someone is really curious, buy one from Randy. It might be a good experience to see how the engine would perform in its stock configuration.
Since I rarely fly anything larger than a .40, it's really not much interest to me.
Besides, with my cars, planes and home to take care of, I really don't have much time for model aviation any more.
Bob Z.
Brett, (and I hate talking over someone else) but it seems that the benchmark here was to 'be' the Tigre 60, rather than being the Aviastar - if you get my meaning.
Everything points to getting that 13x6 to run in a 4/2 break rather than getting the engine 'as is' suitable for stunt.
And that's fine as I am sure that old Tigre style run is still loved by many, and (as you are angling here) its not the only way to skin a cat.
The quote of "the mods shown in the article, you MUST perform them for satisfactory stunt runs," seems a bit limiting.