Motorboy

hi all folks..

I won the OS Wankel engine (NIB) in E:B:A:Y auction. Want to know how long the OS Wankel will last compared with piston engines. What is your knowledge about OS Wankel engine ?

I know the Wankel engine are drinking more fuel than piston engine and more powerful in size.

asmund

Hello Jens. I found this great reading of the OS Wankel: http://ludens.cl/aeromod/wankel/wankel.html

proptop

My Feedback: (8)

Is it one of the older ones or the new one?

A friend had one of the early ones, back in the mid 70's and flew the heck out of it for a couple seasons. It ran quite well...strong for it's displacment, and spun a 9X6 Top Flite wood (sorry, no r.p.m. figures )

I recall it ran great on our club fuel, 10% nitro, 20% oil, until our fuel maker decided to (unknown to us ) use all synthetic oil in our next batch of club fuel, and the Wankel lost it's seals, and most of it's compression and power. (several guys cooked their engines actually, but that's another story )

I think that as long as you don't over-prop it and/or over heat it and use a fuel with castor (as I know you will Jens, because you have much experience![8D]) it should last for quite a while...(who knows for sure, aye!?)

Motorboy

See the pic of the engine..

I never had the wankel engine hence i need to know or some tips to keep maintenance.

Asmund, thanks for the links are informative

Parkerm

My Feedback: (6)

My experience suggests Wankels don't lose their seals they lose the springs that keep the seals tight. The leaf springs are not expensive or hard to replace. Run any fuel you like, at least 20% oil (castor or synthetic or blend) just keep it RICH. Overheating causes the leaf springs to get brittle. The Wankel is happiest at 14,000 rpm.

Gringo Flyer

My Feedback: (18)

Jens,

I have never personally seen a wankel engine run. I am just curious what plane you plan to put this on? It would be a blast to see one fly.

Motorboy

I learned in miscellaneous instructions from oldest to newest wankel engine + readed the test report of wankel engine by Peter Chinn and what i can do it with older wankel engine as here:

Keep oil percentage hight until 25%, best with castor oil to keep tight against leakage and better lasted moving parts.
Run the engine between 5% and 15% nitro. Keep rich mixture and prevent overheated engine.

But i readed about the new version wankel engine from OS, they has replaced glow plug R with glowplug F (for 4 stroke engine) as i can think the compression ratio are improved to keep glowplug glowing and rpm range are same as older wankel engine. The percenteage are reduced to 18% and the wankel engine can use both castor oil or syntetic oil, may be improved material to run at pure syntetic oil.

I am waiting at the wankel engine as i won in E.b.a.y + i ordered the newest wankel engine from Hong kong then i can compare with both engines when i am talking about use and maintenance of the wankel engine.

Here in RCU are wankel engine less wrote and not much to get information from wankel owner, same in other web sites..[]

proptop

My Feedback: (8)

That's great Jens, now we can read of your comparisons of the new and old versions.

My friend that had the Wankel is 78 years old now and his memory is not all that great anymore...[]
He has talked of buying the new version however, but didn't want to spend the money on it if it was not substantially better than the original.

digital_trucker

I knew a fella that had one and the seal springs were shot. It had absolutely no compression when hand-flipping, but would start and run perfectly using a starter. This was one of the originals with the bolt-on cooling fins. It was funny to watch him dead-stick and the prop is spinning merrily away.

Motorboy

I received the OS rotary 49-PI Type II, the newest wankel engine.
I installed the engine to wood plank and mounted fuel tank + propeller 10x6. Filled up fuel tank with fuel who has 10% nitro and 18% (50% castor oil and 50% syntetic oil). Glosed and reopened 2 turns in main needle after the instruction manual. Then i primed the engine and connected battery to glowplug. Tried to hand start the engine without luck, it was very difficult to hand start. The engine are ignite and will oscillate some time, mostly nothing to start the engine.

Why difficult to hand start the wankel engine? [sm=50_50.gif]
Let us see at the wankel engine, the rotor are rotating 1 revolution while the shaft are rotating 3 revolution, also it is not enough to rotate the rotor fast as the reciprocating engine can do it when we are flipping the propeller fast. With the slow rotating rotor are difficult to get compression quickly before ignition. Also the engine are "overgeared" engine who make the engine difficult to hand start(let us say "the engine are 3 cylinder two stroke radial engine with gearwheel at 45 teeth are driving the propeller with 15 teeth" then the engine will go slow while the propeller are hand started, you understand?).

I has not electric hand starter, then i saw at the propeller drive washer has a groove. I got a idea and took the rope and turned around the propeller drive washer, connected to glowplug and started the engine. Hurrah, the engine was easy to start, ran well. I adjusted the main needle rich (3.5 turn from closed). I am surprised the engine are really hotter than reciprocating engine!!! Exhaust gas are insaneous hot.. Since the engine are new, the rotor are not sure adapted to wall in the engine and can have friction to generate hot. I saw the silicone tupe between rotorhouse and carburator was without oil.. adjusted more rich (6 turns from glosed), very much smoke and oily from exhaust muffler, still not oil from rotorhouse and the engine are hot as before. I will wait until the engine are ready and all parts are adapted after running-in, maybe oil will come there. To be sure the engine get enough oil so long the engine are new.

After i ran the engine, then i was afraid in case the leaf spring for apex seal was destroyed by hot. No, compression are still good as before. There are possible to check the leaf spring are ok: remove exhaust muffler, rotate the shaft until you can see the apex seal are visible. Take the thin wood stick and move light at apex seal and feel if spring are ok or defect. It is better do not dismantle the engine before you are checking the leaf spring are defect or the apex seal are stucked by old oil with the thin wood stick.

Before the engine are stored over winter to example, be sure the are soaked in alcohol in some hour and all dirt are removed from engine, check all the apex seals and leaf spring are ok (as i wrote above), give the engine after-run oil and pack in plast bag.

As i learned how the engine are:
Easy to start
Not sensitive to adjust carburator
Smooth and vibrationfree running
Quiter running

I not learned: Will the wankelengine last long as the reciprocating engine, let us see in some year...

Lack of parts in wankel engine: Recoil starter!!

Next time i will upload the movie in youtube.

gzkpez

Nice report. Does it mount the same as the old one?

Motorboy

I am waiting at the old engine to next week.

Motorboy

Today i received the older wankelengine. The engine are unused and can not rotate. Cause the needle bearing in rotor was stucked by gummed oil. I dismantled the engine and lubricated the needle bearing. Moved the rotor around the eccentric shaft some time before the gummed oil was removed. After the engine was cleaned and assembled, compression are good as new.

You can see these picture who are showing inside of the wankel engine. And how to align the rotor at place at backplate with gears at place. How to check the apex seal before use..

Here are the movie of rotor are rotating at backplate with gear inside: http://www.youtube.com/watch?v=eTbg92mRUG4

The ring gear inside in the rotor and the gear centered at backplate are forcing the rotor to rotate and the rotor are transfering the power to eccentric shaft.

The next time are to compare between the older and newer wankelengine

Fastsky

One of the flyers at our field had the smaller engine, I believe it was a 32 size. It had only slightly more power than the OS 32SX engine, went through amazing amounts of fuel, and was picky to tune. The fuel tank was matched to the size of plane which meant short flight times. After he brought it out about 3 times, he pulled the engine and replaced it with an OS 32SX which was a much better performer all around and only sipped fuel. [8D]

Motorboy

I has uploaded the movies and picture of my engines

http://www.youtube.com/watch?v=Gu8RLwWiYiQ
http://www.youtube.com/watch?v=wnQHeN_5PkE
http://www.youtube.com/watch?v=IteLuuT5aw0

I has measured noise of the engine as here pic showed..

Fastsky

Um, it says that your first and third videos are no longer available....[X(]

Jezmo

I got the first and second but the third wouldn't work. Jens, what size prop is on the new one? Old one? Love that sound at idle. Awesome. [8D]

Motorboy

All movies are corrected and are cleared to see.

I am using propeller 10x5.

I must go to job, here are morning...

Flypaper 2

Just as a matter of interest, I used to have a snow machine with a Sachs Wankle around 400 CC. Driving at night the ex pipe would glow a cherry red which was normal. Just to give an idea how hot they did run. Just the nature of the beast. Much more torque on takeoff than the normal two stroke.

gkamysz

My Feedback: (19)

Cool Jens. One of these days when I find a good deal on an OS Wankel I'll buy one.

This came up in the related videos a twin OS Wankel tractor puller.

http://www.youtube.com/watch?v=eOlpiZ0xFzk

gkamysz

My Feedback: (19)

http://www.modelbouwforum.nl/phpBB2/...ght=nsu+wankel

Here's a picture of that twin OS Wankel setup.

projecthog

Nice post Jens,

I have an older type 1 wankel and I wonder if the timing on it is the same as yours. Mine is used and pretty beat up but wants to run, I just have to re-do some of the assembly srews to get the compression back to normal and then I will attempt to run it again. These little engines are a blast, and I wonder if there is anyone who might have some more info on it. Thanks for your pictures they will probably help a few of us who like to tinker with them. I have a type 11 PI coming soon so i will have both to play with. Tanks,
PH.

bishop stortford

I have been fascinated by the Wankel engine since it first came to my notice. I drove the first NSU Wankel Sport Prinz that came into the UK. I almost bought a used NSU Ro80, years ago, but perhaps wisely didn't. My first Model Wankel engine was the early version with the cooling ring. It started easily and ran smoothly but I didn't want to fly it because spare parts are not available now. I recently bought the new PI Mk. 2 from a Hong Kong store with the intention of using it in a lightweight plane (which was previously being flown with a brushless electric motor!). It will not be flown as my principal plane
Now we get to running-in the new one on a test stand. First impressions, with a 9 x 5 prop., it will not yet idle at much less than 4000 rpm, and throws out an extraordinary amount of (castor) oil, high fuel consumption, appears to be more than the early engine, at least I know that a lot of oil is going in. Seems quite powerful, but I think it will need a lot of running, and adjusting before I fly it. I am a little worried by the apparent gear noise at low speed, when it is going in and out of a rich, light '4 stroking' Would like to change to a part synthetic mix later. Any other experiences of this engine?

Motorboy

This is cause the rotor are 3 times slower than drive shaft and can not be slower as in the ordinary 2 or 4 stroke engine who are rotating at 1500-2000 rpm in idle.

When the engine are running at 4000 rpm then the rotor are rotating at 1333.3 rpm. If the engine had the rpm at 1500-2000 rpm, it will be impossible to run the wankel engine with rotor at 500-666.6 rpm, also lower than 2and 4 stroke engines..


The gear in the wankel engine are noisy cause there are straight-cut gears, if the engine had helical gears then noise will be less, but the problem are side thrust by helical gears.

Nothing to be worried about noise in the wankel engine by gears under low speed.

I will recommented to use castor oil in the wankel engine since the engine are more hotter by "full time" combustion in same place in the rotorhouse and there are difference brands of syntetics oil and not all syntetic oils has same flash point temperature, some can be low and some can be high in flash point temperaure, there are not a warranty againt the syntetic oil are preventing against burn in combustion while the engine are leaned out.

In the newest OS 49-PI Type II wankel engine are well designed to run with 50% castor oil and 50% syntetic oil in total 18% oil in fuel. But never lean out the engine to max rpm, let it run with a bit rich fuel to keep engine cooled and enough lube.. Think, in air with model airplane, the engine will spin more and the fuelmix will be leaned!

Parkerm

My Feedback: (6)

I have 3 of the later models and have been running them on 100% synthetic oil at a mix of about 20% without any major problems. I probably don't have as many hours on them as some people but have found that the synthetic is less "gummy" than castor so a prolonged idle time (like all winter) does not lead to a stuck engine.