bdog1

Merry Christmas to All !
I am looking for some info and advice on this motor
Does any one out there have experience running one of these ?
I am wondering about prop size, pipe length, aprox rpm's

Mike

dhal22

interesting engine. is that a prop drive reduction unit?

doxilia

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Mike,

Wonderful history of these engines!

I believe that OS didn't produce an engine larger than 10cc in capacity until 1983 which marked the first OS 108 (the 91 came later). In order to satisfy TOC requirements (and similar) when the ships started to grow in size (remember Hanno flew the Magic to worlds in 1982), they came up with a gear reduction system allowing a 61 to be used in 6' span birds. I believe the output was similar to something in between a 91 and a 108.

Of course, Hanno used a simple dual Webra Speed 61 configuration (or were they 91's Flywilly?) with no gear reduction on his Dalotel at one of the TOC's (I forget which year) roundabout that time.

I'd try setting it up with props used on a 91 - something in the range of a 13-15" prop (choose diameter and pitch according to application). You could start with a 13x6 and move to a 14x6 or 14x8 if it appears to be over revved. It should probably spin somewhere in the range of 8-10K rpm given the (ungeared) VF was a higher revving engine. It's probably going to be similar to a 61 Hanno but might spin slightly more prop at a little less rpm.

This engine would be great in a slightly enlarged 60 sized Dalotel for which I have some fantastic plans!

Merry Xmas!

David.

NM2K

My Feedback: (14)

OS produced an .80 CID engine at least as far back as 1968. It was a rear induction, baffle piston engine. I can't remember the exact nomenclature, but it was something like OS Max H.80F. I've seen quite a few of them at the old R/C fields. They ran great, but they were not significantly stronger than their 10cc cousins, with one appearing identical to the .80 version (swept upward carb mounting position on the rear backplate, IIRC).


Ed Cregger

doxilia

My Feedback: (3)

Thanks for clarifying that Ed. I stand corrected.

Picture of H80RC depicted below. Production year, 1967.

David.

flywilly

My Feedback: (121)

The geared OS engines worked pretty well, but were unbelievably noisy. Not prop noise - GEAR noise. It was a weird sort of a 'whine', but not a high rpm prop scream, Of course the engine was screaming at 14,000 rpm or more, too. There were 2 reduction gear ratios available as I recall (of course I can't remember what they were...[:@]), but I'm sure that information is in a World Engines ad from that time period. 4-strokes pretty much killed the geared engine concept.
I think Hanno used 2 geared 91s with tuned pipes turning a 16" prop. I'd have to research that to be sure.

MMcConville

My Feedback: (4)

I remember these. Actually, OS produced a .91 FSR in the later 70's. The first year the TOC went to scale models, which was 1978, several pilots used them. I know Brown used one in his Zlin 50. in 1980 ,TOC pilots used them on the Cline belt drive in the 85" Ullery Laser. I believe Dave Brown, Mark Radcliff and a few others.
The OS 1.08 came out in 1981 or 1982, which was essentially a punched out .91.

The OS gear drive engines were as I remember primarily for F3A and some scale model. That was before F3A had gone to turnaround but there was talk of slowing down F3A models, OS came out with these.

I remember Tony Frackowiak's first Challenge 1 was built around one of these engines. In 1982 when he built it, it was HUGE for pattern. I lost my Tipo at a contest that year and Tony loaned the model to me for the weekend. I remember that it flew great!!
What killed this concept was the beginning of noise limits which started at the 1983 Team trials. (was 105db at 3 meters I think).
As someone mentioned, the gear noise from these was terrible and they had no chance of meeting the noise limit and quickly faded away.

doxilia

My Feedback: (3)

Mike,

thanks for the brief history and further correction to my quick incomplete research. Indeed, the 90FSR was announced by OS in the 78-79 time frame. Picture attached.

What advantage if any, would there be to running one of these engines today vs a regular 2 stroke 91 (assuming one had both...)?

David.

TonyF

My Feedback: (92)

I used the gear motors quite a bit. I actually built my own single O.S. .61 gear drive system before O.S. produced their geared engines. To make a long story short, there really is no advantage to them over a larger engine. But back when they were conceived the engine limit was still .61, so there was a need for something that would swing a larger prop. With the allowance of 1.20 for 4-cycles they proved to have a very short life.

bdog1

Thank You for all the replys !
I will try to respond in order, Yes Dave it is a gear reduction unit,the one I have seems to be about a .75 to 1

I found a 60th aniversary version on the OS chart you sent Dave,funny it had more engines on it including the GS A-2 I think I have. This motor is off of a Ed Keck pattern ship from that time period,The name on the plane is "Grand Slam"-please see attached picture
It is larger than a Rossi .60 powered ship of his that I also have.
I know that Ed designed a TOC Spinks Akromaster around this time frame.
Thanks Dave
I am trying to document Ed's pattern designs and also establish a time frame when they appeared.
I have seen a couple of his later ships that were powered by Enya 120 R's and were tail dragger's ,Personaly I prefer the trikes that were common when I started hanging out at the local flying field as a kid.


Ed,Mike,Tony Your comments confirm the evolution and progression of pattern that I have noticed with Ed's ships.

I believe that back in the Classic days of pattern there was a builder of the model rule,Could someone elaborate when that changed?
flywlliy :I am looking forward to hearing the whine you described ...for a while anyway
Mike

joefroooo

My Feedback: (10)

That is sure a neat engine. Looks like it would take up alot of fuslage nose area to get the shaft on the thrust line. I take it the engine uses normal tractor props and the engine is timed for CCW rotation.

TonyF

My Feedback: (92)

Ed was a good friend of mine. He went with me to the 1985 World Champs in Flevohoff. He was a great modeler and I'm glad to see someone is trying to document his designs. I wish I knew more myself.

I don't know exactly when the AMA removed the builder of the model rule. But it was pretty much ignored for a long time and it was a good thing when it was removed. I don't believe the FAI ever had it.

bdog1

Yes Joe :check out a front view of the Grand Slam with the motor installed.

Thank You Tony, I have some leads on some of Ed's other friends that I hope will be able to provide some help.
I know that Ed designed a .60 pattern plane for Maco Models called "The JetStar" and that he campained a model called "StarFire",the other ship I have of his seems to be a refinment of the Starfire design.
If you happen to run across any pictures that pertain please remember me.
I have started to reverse engineer the plane I have so that I could build another,I am no where near the craftsman he was ! -Mike

lfinney

My Feedback: (44)

the os ga 1 and ga 2, and the open gear drive setups werent fun to service or maintain, os wasnt happy with the actual service life of their design either, nice ofr collecting i guess...

52jaws

My Feedback: (65)

Interesting post....been a while since someone has posted on here. I have three of these new in the box although mine are rear induction. The front casting with the two locations for the the carb has been left cast closed. I assume these are later versions as the poster catalog with it shows the front intake versions only. Technically these instead of being ....GS A-1 they are GS-R1.

Michaelj2k

I have the GS A-2 with the side exhaust. I've thought about converting it to a standard .61FSR by removing the gearbox and replacing it with a standard nose case (if I could find one). Any thoughts?

impactiq

My Feedback: (57)

I'll check to see if I have what you need to do so.... Drop me a PM.

bjr_93tz

It's a MAX 61VF abc GS A-1 according to the OS catalogue I have from year unknown?

Reductions are listed as 1.391 for the rear exhaust 61VF GS A-1, and 1.895 for the side exhaust 61FSR GS A-2. The number of digits after the decimal point doesn't make sense as those coming from countries that still use fractions will quickly notice, as you can't get a reasonable number of teeth on each gear from those numbers.

The catalogue doesn't specify a RPM range or power output, so I'd hazard a guess the port timing is identical to it's non-geared brother and would be happiest turning the same rpm (2,000-17,000, with 1.8hp at 17,000).

The OS part number for the gearbox unit, is 40100100.

Cheers
Brett

Michaelj2k

Here's some information.

lfinney

My Feedback: (44)

as i posted earlier you can use the geared setup..but the lifespan of the gearbox was poor, and is why OS stopped producing them, converting it back to conventional configuration is fine.

Sport_Pilot

I think that it was rare, probably because if you needed a larger engine the Fox .78 was stronger. Later the .60's made for pattern was stronger than both.

Michaelj2k

Now on the 'Bay item 170809039126. It's a GS A-2.

Michaelj2k

WOW!![X(] http://www.ebay.com/itm/Vintage-O-S-...item3f15da4f90

Gitamae

Good Evening Brett
I saw that you were from Toowoomba, I am from Orange in NSW
I have been going through this old post and this post has been very helpful, just trying get as much info as possible.
I have just purchased a OSMax 61FSR GS A-1 engine, it has never been run and still in its original box.

However it has no documentation and there is next to none I have been able to find.
Do you have any info on this engine.

Thanks
Steve
.

bjr_93tz

This model was designed for one.
https://plans.modelaircraft.org/product/eagle/

Dad built one as a sport plane around 1990 and put a .75 in it.

Edit: Didn't notice it was a resurrected thread.
Steve, I noticed on on a certain RC trading site. Is that the one you grabbed? I've never owned one or had anything to do with them but they're a cool bit of F3A history..