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OS GF40 4-Stroke Petrol

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Robert Welford07/06/2020 18:22:39
204 forum posts
4 photos

I was wondering whether anyone owns an OS GF40 4-stroke petrol engine as I have just acquired one.

  • If so, what is your experience?
  • What model have you used it in?
  • Best propeller?

Robert

Alan Gorham_07/06/2020 18:31:29
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1291 forum posts
145 photos

I've had one for around 3 years. It's a very straightforward, usable engine. Mine is fitted in a Precedent Stampe and I have only ever used an 18 x 8 APC prop. Flies the aircraft with authority but will cruise on around 1/2 throttle. I like it, but then for the price I paid for it I'd hope I would...

Robert Welford07/06/2020 19:34:02
204 forum posts
4 photos

Thanks Alan.

I'm planning to use mine in a Toni Clark 1:3.85 Super Cub. The power should be adequate and sound better than a petrol 2-stroke.

Edited By Robert Welford on 07/06/2020 19:37:39

Alan Gorham_07/06/2020 19:58:22
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1291 forum posts
145 photos

No arguments on that score!

MattyB09/06/2020 21:29:37
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2097 forum posts
32 photos

My Dad bought an NGH38 for his Seagull Spit, but despite that engine running well on the bench he decided to go with the OS instead. It is certainly a more refined engine, and seems to start and tone very straightforwardly - no issues to report it just goes!

john stones 110/06/2020 08:48:51
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11590 forum posts
1517 photos

Watched a video of one, sounded great, he said 97 db at 10 feet, what you lads think ?

Robert Welford10/06/2020 11:31:37
204 forum posts
4 photos
Posted by john stones 1 on 10/06/2020 08:48:51:

Watched a video of one, sounded great, he said 97 db at 10 feet, what you lads think ?

Please provide link - thank you.

Alan Gorham_10/06/2020 12:07:23
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1291 forum posts
145 photos
Posted by john stones 1 on 10/06/2020 08:48:51:

Watched a video of one, sounded great, he said 97 db at 10 feet, what you lads think ?

Unless I knew how and where those measurements were taken, I'd place no faith in them.

Put it this way: it is not as irritating as a DLE with a cheap muffler (or an expensive one for that matter!).

john stones 110/06/2020 14:42:11
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11590 forum posts
1517 photos

**LINK**

Alan Gorham_10/06/2020 15:04:10
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1291 forum posts
145 photos

So without even playing the video I can see the engine is being run over concrete. BMFA recommends testing over grass IIRC. Plus the prop seems small. My prop has a very broad blade which must help keep the prop speed down. Nah, not a very meaningful test for me.

Edited By Alan Gorham_ on 10/06/2020 15:04:24

MattyB11/06/2020 20:21:55
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2097 forum posts
32 photos

Sounds lovely in this video of a Seagull Spit - the music finishes at around 2m30...

john stones 111/06/2020 20:48:21
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11590 forum posts
1517 photos

It does, cheers Matty. note

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