[itsme]

I'm not sure what the ratio should be either, but I do know that the NSU KKM 502 has an offset of 0.2cm. The rotor radius of that engine is 10cm and the eccentricity is 1.4cm. The offset is clearly not very large.

Warren

[Eson]

Here is some spec. about the Mazda 13B engine: http://www.sae.org/automag/global_viewpoints/01.htm

E=15 mm, R=104 mm, 80mm width house, equals 0.65L per rotor; 0.65L*2 = 1.3L

I got a PDF of meny kinds of formulas for compression, displacement etc for the wankel, you guys want it?

[Klox]

I was wondering, why not get hold of a 13b rotor, rotor housing and sideplates. Digitise them and then scale down to whatever size you want....
These guys at Racing Beat, (they are situated in Anaheim, Kalifornia) http://www.racingbeat.com would have the goods to help you.....

[itsme]

Klox, I couldn't help but notice your location. I'm from Johannesburg (well, the Fourways area), but I've now been living in the UK for 2 years.

You could always 'copy' Mazda parts, but it really isn't difficult to generate the shapes from the equations, which would possibly be more accurate (although I don't really know what the accuracy is like with a digitising probe). A Mazda engine would still be useful for other details of the design though.

Regards
Warren

[Klox]

Warren, nice to meet you! Digitising can be very accurate depending on who does it.....
I just chucked a (little) rock in the bush by staing to copy and scale an existing motor. Some people might consider it as a way to achieve the goal....

BTW i'm from the northern side of Pretoria, what are you doing on "mud island"? (Sorry could not help myself, the British members will put me on the top of their "hit" list- Sorry guys!!!LOL!!!)

[fyffe555]

Klox, Itsme,

Small world.. I'm a Brit - lived in Chatsworth, Durban for a couple of years, have relatives in Pretoria and near Kyalami.. 'mud island' - hah - haven't heard that one for a while!

Eson

If you could post your PDF I'd like to see it?

thanks..

Andrew

[Eson]

Here you go: http://hem.bredband.net/b235625/chapter7.pdf

[fyffe555]

Eson, Thanks, interesting chapter. What book is it from?

Andrew

[Eson]

fyffe555; No idea. Found it on a site, dont remember which site.

[itsme]

Hi there,

What am I doing on Mud-Island (which I have discovered is a VERY appropriate name...)? Well, my Dad was transferred here and since I am still living at home - here I am! It really isn't that bad though (besides the weather) and I definitely don't miss things like the taxis in good old Jo'burg(Klox, you'll know what I mean ).

There were a lot of good books printed back in the 60's and 70's about rotary engines, but sadly not many (if any) are still available and the original ones tend to be quite expensive. The link that Eson posted appears to be from a newer book though. Does anyone here have any of the great rotary books, such as the one by Kenichi Yamamoto?

Regards
Warren

[itsme]

Hello again,

I have finally got my mill half working. At the moment it just has 2 axes working (x and y). I haven't cut any parts with it yet, but I have put a pencil in the chuck and drawn a few 'pictures'.

One of the 'pictures' that I drew was an epitrochoid and it turned out very well. I know it is only a pencil drawing, but it seems to be very accurate. This epitrochoid is 120mm long (biggest dimension) and it would be suitable for an engine of about 50cc capacity.

Regards
Warren

[RotarySMP]

It is pretty fascinating to get a machine to move under it's own power for the first time. Congratulations.

[wolfgang]

I'm for it. my 79 rx7 needs a rebuild anyway!

[polarit]

is this thread dead ??
or is someone working on plans ?

[arpieb]

It looks dead - but shouldn't be with the work acomplished by itsme... I'm actually about to invest in a mill and CNC conversion so I can explore some "alternative" combustion engine designs as well...

BTW - the link to the exhaustive "Chapter 7" on Wankels is part of a larger energy eBook that can be found at:

http://www.personal.utulsa.edu/~kenneth-weston/

Any updates on Wankel model plans would be greatly appreciated - hoping to not duplicate errors or work done by others...

-R

[wolfgang]

I'm still monitoring.. I have not had time to try anything yet.. I bought a 1/10 scale reproduction "running engine" but it's plastic, and not as useful as I hoped.

[itsme]

Hi there,

The plans that I used for the engine that I built were roughly based on the SW92 plans that are available from www.vth.de . In the end, my engine resembled the SW92 externally, but internally it was quite different. I used a proper epitrochoid, where the SW92 used an oval. I didn't ever make 'formal' plans for the version that I made.

If you do decide to try and make an engine, pay particularly close attention to the apex seal and spring arrangement and make sure your fixed gear is solidly mounted and generally robust. These were the two areas that I had the most trouble with. If I were doing it again now, I'd also avoid the aluminium side housings that I used and rather go with steel or cast iron.

Those plastic models are great to get a feel for how the geometry works and how the engine generally fits together, but when it comes to the finer details, they're probably not the best things to copy.

Regards
Warren

[jgro]

Someone earlier in this thread aked what happened to Wankels from the 60's and 70's. I happen to have one in a '71 Arctic Cat Panther snowmobile that I'm restoring. I took some pictures of it as I tore it apart so that I would know how to put it back together again. Enjoy!

jgro

[polarit]

Funny thing with the wankel engines - sometime whole lives revolve :-) around them.
when i was born in mid-sixties my father was working in stuttgart at the NSU plant, with the apex seals.
When i was 2 cents high, i was transported around in first a NSU Spider, and later a RO-80

A historical info : when NSU drivers met at the highways in germany, they saluted each other with a raised hand, showing a number of fingers.
each finger represented a engine change.

and now - wouldn't it be nice to build one myself, just for the bragging rights.

...might finish the cnc mill first thou.......