Os wankel Rotary engine - RC Groups
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Jul 12, 2004, 10:19 PM
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Os wankel Rotary engine

ok ok , im not really a plane guy but i need Your guys knowledge for something , I LOVE rotary engines , i own a rx7 , BUT when i heard of the os rotary engine i went nuts , OK let me get to the question I like tinkering with my Go ped , and i asked on a go ped forum if the os wankel could be used they said no , Ok but you airplane guys should know , so the question is COULD the OS .30 or which ever model , if i mounted it to my goped could it produce enough to push a human??? i mean the go ped engines now are like 30cc or less , and less than 10,000 rpms and the Os .30 says 17,000 rpms so they can produce more than enough rpms ,so how big exactly is it?? could it compare to the size of a Weed wacker engine??? or smaller? if the Os IS too small for what i want to do then ok ..........But ive been researching wankel engines in aviation and i saw the "WANKEL GMBH" Ring any bells?? but anyways that looked pretty cool too well thank you guys
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Jul 12, 2004, 10:27 PM
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wakumann's Avatar
Superican: wrong forum,
anyway : Rotary Engine was developed/ invented by Felix Wankel in the ~60s.
Car-engine in NSU (now AUDI) Modell RO 80 ( my father had a few) , Patent sold to Yapan (Mazda) in the late 70's.
Graupner still sells 2 Wankel(Model) motors fabricated by OS

Jul 12, 2004, 10:35 PM
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corey's Avatar
The O.S. .30 is way to small for a go-ped, but it does have a LOT of jam for it's size....sounds wild as well with VERY good throttle response.
Jul 12, 2004, 10:44 PM
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thanks you guys , hey what should i look into in that Graupner website?? lol
Jul 12, 2004, 10:55 PM
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Don Sims's Avatar
http://www.rotaryrecycle.net/main.asp?pg=intro.asp is the klink to a motorcycle rotary engine site. One of my all time favorite bikes is an RE-5 Suzuki.

Sorry to get off topic but rotarys are facinating motors!
Jul 13, 2004, 08:21 AM
Speed Demon
GregG's Avatar
This is a bit off topic in the Electric High Performance forum. It's probably off topic in any of our forums but I'll move it to the Airplane Talk forum so that the fuel flyers with more experiance in regards to this can give you thier opinions.

Since the engine you're looking at makes it's max horsepower at a much higher RPM (17,000 vs. 10,000) than the old go ped engine you will have to gear things down quite a bit to even get it close to working.

Best of luck in your new project!
Last edited by GregG; Jul 13, 2004 at 08:24 AM.
Jul 13, 2004, 04:34 PM
Registered User
The Graunpner/OS/NSU .30 Radial is a poor choice for a go-ped. First reason is not enough power, second is heat. These motors run very, very hot-they don't like cowls or .30 size props on an airplane. They are timed to run about 1-1.5" dia. less than an equivalent .30, but man, are they fast. I don't want to quote RPM figures as it's been 10 years since I flew mine regularly, but suffice to say it out turned .25's of the day handily.

Very poor fuel economy too, as with all rotaries.


Edited to say: Look on Ebay for the Honda GX25, or 31CC weedwhacker motors. They are quiet, make 1.1/1.5hp and have a lot more torque than a 2-stroke motor. No mixing of gas needed and the can be mounted at any orientation and the sump sprayer will still do a good job of keeping the top end lubed. They burn about 1lt. per hour-Waayyy better than a 2 stoke!
Last edited by Dave Campbell; Jul 13, 2004 at 04:37 PM.
Jul 13, 2004, 06:58 PM
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well could i ask what other rotary or if there is any more rotary airplane small scale engines out there , what could i apple to a goped
Jul 13, 2004, 10:50 PM
Registered User
Hobby Lobby used to sell a large rotary (several cubic inch) years ago, but it was an $1800 engine and didn't sell well. If you can find one, expect it to be every bit of the new price-and if you did use it, you'd better pray to gods of wiper seals that you can find spare parts...

I know that Rotaries are what you have your heart set on, but there aren't very many of them (for a good reason too) out there. You would be best served by some form of 2 or 4 stoke weed-whacker motor. The only other rotaries I know of that were ever manufactured in numbers that would support spare parts are the Sachs 35hp engines that were used in snowmobiles and generators in the 60's and 70's. Have you tried Ebay? That will give you a good idea of what was once available.

I was in a similar spot to you a few months ago when I was looking to put a motor on a mountain bike. I went with the Honda GX31, from Ebay for half retail price.

Have fun!

Jul 14, 2004, 09:44 AM
Proud Pro Bro # 13
Ulf Rieder's Avatar
moved once again tho the engine forum.
Unfortunately I know nothing about wankel engines either. Good luck.

Jul 14, 2004, 04:06 PM
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Tony Oliver's Avatar
We won't move you on - engines are engines - if it could be used in an aeroplane we'll talk about it!

Take a look at https://www.rcgroups.com/forums/showthread.php?t=243451 which has some discussion on the larger Wankel than the OS30 size and power output.

I would think any size would be possible for your purpose. It's the gearing that counts. Problem is small is slow.

Jul 14, 2004, 07:23 PM
Registered User
i would love the fetchel and sachs wankel BUT there is practically no person that will sell one nor is there any websites with enough info , THey all are in german also there was a chainsaw engine wankel made by sachs in the 70s , but they all are considered Antiques and that "A" word means a lot of $$$$ ........Ohhh ya and how do AIrplane carbs work?? i know they dont run on regular gas or in my case a gas an oil mixture....do they inject or does the piston create suction an pull what is needed???
Jul 15, 2004, 04:16 AM
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Tony Oliver's Avatar
I'm not well up on 'gas' engines - anyone help here? Walbro carbs seem to be very similar to car carbs, and fuel? Differing oil content seems the only variable.
Jul 15, 2004, 04:36 PM
Registered User
In full size 2-cycle airplanes, the gas is pre-mixed but a few higher end motors have "autolube" injection where the oil is introduced to the intake via a crank driven pump a la motorcycle practice.

Jul 17, 2004, 04:57 PM
supreme being of leisure
ZAGNUT's Avatar
i think you're mistaking the .30 cu. in. for 30cc....the OS wankel is less than 5cc.

i believe mecoa has a 20+cc wankel. would not be cheap though.


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