hrrcflyer

Greetings to all you motor guru's,

A friend at the field where I fly brought a plane to the field yesterday. The plane had, what appeared to be an older OS 40 with "MAX H" stamped on the side of it. He asked me if the engine would work in a 40 size P40 arf. I told him that I was not familiar with the engine, but I would find out what I can about it. So, what does the "MAX H" stand for? The engine runs very well and seems to turn a Master Airscrew 10x6 at quite a good clip.

Any info on the motor would be greatly appreciated.

Thanks in advance for the assistance.

NM2K

My Feedback: (14)

I don't know what the "H" stands for in the name myself. I've flown two different samples of this engine, long ago, and was very happy with it. It is not as strong as today's engines, but it is no slouch either.

If the proposed model is smallish to medium size for a .40 sized engines (52" span with a weight of 5.5 lbs.), the older OS Max .40 H should provide very acceptable power for average sport type flying. If the model is a tweener (sized between old .40 and old .60 sized models), something with a bit more power might be a better choice. This also depends upon one's expectations as much as the model size and weight.

My OS Max .40 H engines powered Andrews Trainer Masters, which is not small for a .40 sized engine in the least. One of them had a heavy silk & dope finished fuselage with Super Monokote covered wings and tail surfaces, making it far from a light weight. Probably in the neighborhood of 6.5 lbs. This model was fast for its day (1971) and could easily keep up with the .60 powered pattern ships of the day. I loved these engines and, while I no longer have the originals, I have accumulated two or three of them off the used market during the last several years. I intend to build another Trainer Master and power it with the engine that I used on my "first low wing" model, back in the day.


Ed Cregger

Broken Wings

My Feedback: (20)

The Max H series engines will surprise you. I run a H-80 and it will spin a Rev-Up series (2) 16x4-1/2 like no-bodys business. Run good fuel with castor oil and it will keep running a long time.

The strap-on mufflers work great as well.

correction, was 16x6 went out and looked at it 16 x 4-1/2....

blw

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This is an engine that was sold in the mid 1970s. Currently, the H would mean a modern OS engine is for helicopters.

Broken Wings

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I don't think any of the OS MAX H series were Helo engines. I could be wrong.

hrrcflyer

At first I thought it may have been a heli motor too, but it didn't look like any heli motor I've seen before. I wish I could show you guys a picture of it, but I don't have a digital camera.

Keep all the good information coming. Thanks again!!

rcdude7

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Looks like this:

rainedave

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Here's one of mine. They are good sport engines. Just use lots of castor oil in your fuel. Do not use all-synthetic oil fuel.

David

larry@coyotenet

My Feedback: (21)

If I remember correctly the H stood for High Performance. I have both the OS 40 and the OS 40 H and the H is quite a bit more powerful.
I would put it up against most of the 40 size engines in power but not the same as the schnurle ported engines. I ran one several years ago against Thunder Tiger 40's in quickie racing and was probably down about 1500 rpms on a 9X6 prop. Puts out about the same power as the K&B 40.

Larry

rainedave

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I need to check the OS Max-H against my Webra BH .40. It will be interesting to see how they compare.

David

proptop

My Feedback: (8)

I'm pretty sure that the H has a wider bypass area/passage in the case than the previous MAX .40 and you might be able to look at the earlier engines on the O.S. time line site for a comparison?
That could be at least one reason for the H as in "High Performance". (don't know about the C.R. or timing )

I have 2 of them, and have run a few others in the past...nice running engines, and like mentioned above use plenty of Castor oil in the fuel, and no more than 10% nitro is necessary. An idle bar plug might come in handy as well.

O.S. Timeline:
http://www.osengines.com/history/ostimeline05.html

Look at the difference between the '69 and '72 versions of the case.

NM2K

My Feedback: (14)

One thing to keep in mind is that OS often released new models in Japan a year or two earlier than they appeared in the USA.

The H.40P wasn't released in the US until AFTER the H.40 was released in 1970 or so in the USA. I had both engines. Couldn't tell any difference in power output or handling on the same prop and fuel. An idle bar plug is standard fare for baffle piston engines.


Ed Cregger

downunder

The first series of the H40 had a smaller transfer passage and only a single rear ball race except for the H40P which had twin ball races. Their bore and stroke was also different to the later engines. With most of them there was a letter stamped under the 40 to indicate which model it was. P for pylon, RR for rat race, S for stunt and if it was blank then it was RC sport. The later (and much more common) H40's were only intended for sport RC flying so no letters were used.

rainedave

My Feedback: (1)

The one in the picture I posted has a conventional ring. I have another one that's in poor condition, but still runs, that has a Dykes ring. It was supposed to be a little stronger when new.

It's a little hard to see the Dykes ring in the photo, but that's it.

David

hrrcflyer

Thanks for all the information fellas, I really appreciate it!!

proptop

My Feedback: (8)

Everything you ever wanted to know about the O.S. Max .40H... but weren't afraid to ask...[)]