Helicopter engine? What do you think?

Here is my question to an Ebay seller of an O.S. Max .40-H R/C engine and his answer. What do you think about the answer? Is this a standard .40-H or something else (helicopter engine?)

Dear td40,

You asked:
"What indicates that this is a "helicopter engine"? Is it the H in the side of the engine as in O.S. Max-H or is there some other indicator on the engine that designates it as a "helicopter engine"? It looks very much like my standard O.S. Max-H .40 engine that I use on my R/C trainer........Thanks.....Terrence Durrill in Platte City, MO."

I contacted O.S. for information on this engine. It is a helicopter engine and it is indicated by the -H. I'm not really sure if there are any real differences internally. Thanks for your interest.

The item is at: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=5929467716

Tom:
From the strap-on muffler and the previous MAX - H discussions here, I would peg the guy as wrong.
With the large number of good and reliable Stunt engines available to us today, I get to wondering why someone bothers with one that is out of production, and wasn't all that sought after when it was being made?

See Ya

>Tom:
>From the strap-on muffler and the previous MAX - H
>discussions here, I would peg the guy as wrong.
>With the large number of good and reliable Stunt engines
>available to us today, I get to wondering why someone
>bothers with one that is out of production, and wasn't all
>that sought after when it was being made?
>
>See Ya
>
>Peabody

Peabody,

Yes, I am sure you do.

What I wonder about is why you have yet to answer some pretty serious questions concerning the outrageous statements you made on this site, what was it?, three weeks ago?

I know accountability is hardly your strong suit, but I am certainly interested in seeing how you handle this. To date, I am not very impressed.

The H is not helicopter as I understand. George Aldrich told me once that the H is a good stunt engine with a lot of grunt. I have three of them and ALL have BALLS. Wish I had something to put one in.

OS did make several variations of the MAX-H .40. This may well be one of a lesser known (unknown?) version, but I have to agree with previous posters that feel that this is a standard MAX-H .40. However, I think I see an extra large "groove" in the prop drive washer that I have not seen before. This could be there to allow the use of the starter belt necessary to start a helicopter engine. The groove could have been milled by an owner who wanted to use the engine in a chopper. Or...that same user may have found a prop driver from another engine that would fit the MAX-H .40 and installed it.

After looking at the OS engine model timeline (Thanks for the link, Currell.), the earliest engine I see specifically designated for helicopter use is the .45 FSR-H from 1977.

http://www.osengines.com/history/ostimeline06.html

It has the typical large heat sink, either integral to or attached to the head, that is necessary for proper cooling in a helicopter installation. The lack of this heat sink would further indicate that the example in the auction is not a factory built helicopter engine.

As far as the answer from OS stating that the engine was indeed built for helicopter use, it's entirely possible that the person who works for the current importer who answered the question for the seller either does not know what he's talking about in regard to older engines or he didn't have enough information to answer the question accurately. Looking at the same model time line, it appears that all the engines since that 1977 .45 FSR-H that have an "H" in the model designation are helicopter engines. The person who answered may have seen the "H" in the model designation and assumed that every engine that OS has made that had the letter "H" as part of the model designation was indeed a helicopter engine and composed his reply to the seller accordingly.

WELL.....I do know that there are two different 40-H Two different bores. Frank Bowman has the answers. I THINK one is .806 and the other is .833? Frank would know.

For Beer cove Alaska dude.....How's the weather? ART Z. say's hi. He's one of my Students.

Scott,

That's Beer Can Cove, Alaska. Art's Twister looks pretty good. He said that you had a hand in getting that one together. I also understand that his wife is up here visiting an offspring. The weather is a bit chilly, but nothing to get upset about.

I was just on the phone with a flying buddy asking him why we weren't flying today. The high temperature was about 45° F today, and we felt it was a bit too chilly to fly. However, if we were to have this weather in late March or early April, we would have been falling all over ourselves to get out flying. What a difference in perspective a season makes, eh?

>Scott,
>
>That's Beer Can Cove, Alaska. Art's Twister looks
>pretty good. He said that you had a hand in getting that
>one together. I also understand that his wife is up here
>visiting an offspring. The weather is a bit chilly, but
>nothing to get upset about.
>
>I was just on the phone with a flying buddy asking him why
>we weren't flying today. The high temperature was about 45°
>F today, and we felt it was a bit too chilly to fly.
>However, if we were to have this weather in late March or
>early April, we would have been falling all over ourselves
>to get out flying. What a difference in perspective a
>season makes, eh?

It's been the best season to fly here. Lots of Great weather. Going out today...I hope. Got props to test.

Just because the engine came out of a heli doesn't mean it is a heli engine. Early helis used regular airplane engines. Most heli dedicated engines have a large heatsink head. This one does not have the heatsink head. Draw your own conclusions.

>Just because the engine came out of a heli doesn't mean it
>is a heli engine. Early helis used regular airplane
>engines. Most heli dedicated engines have a large heatsink
>head. This one does not have the heatsink head. Draw your
>own conclusions.

Ron B.
F4Fguy

True, but most early heli engines have time/areas very well suited for UC stunt.