OS wankel apex seal springs
 

Hi

Anybody got a set of OS wankel apex seal springs they would be willing to part with? Everywhere I have looked shows them as out of stock or back order and this is no doubt because parts are long out of production.

Otherwise has anyone ever made the springs from strip stock?

I have a fully disassembled engine and everything appears to be there expect the springs. The original owner probably took it apart due to overcooked springs.

Cheers
Tarquin

https://www.towerhobbies.com/cgi-bin...?&I=LXCV66&P=7

It says mid December at Tower.You order them and see what happens. Do they really look like these? Thanks, Dave

Back in the early 1970s I had one of the first design O.S./Graupner Wankel engines.

It failed after about 20 minutes total run time.

The rotor tip seals looked OK. However, its loss of compression was due to the poor seal between the sides of the rotor and the front and rear cases. There is a lot more contact and wear there than on the rotor tips with no seal of any sort.

Even then, it was a monumental problem to get any parts. Additionally, to replace the rotor and front and rear plates would have cost more than replacing the engine. Consequently, given its extremely short life and extremely high replacement purchase cost, the engine was just tossed into the junk parts bin.

Subsequently it was sold off as a instructional Wankel demo to show how it worked internally.

Overall it was an interesting experience from start to finish but in no need of a repeat.

By the way, if you do get seals, do check closely. On mine, there were two springs on each tip seal. the tip seal is a separate piece, pushed against the rotor housing by those springs.

I had two of them at one time, I used to say it had the power of a .60 and the fuel consumption of a .90 and was heavy as a 1.20.

Quite accurate.

I would add though that is was quiet and very smooth. To test this, I once ran it while holding it in the hand. No problem.

Hobbsy and do335a that is indeed what they look like. They are 0.2 thick, 1.8mm wide and 12mm long. There are suppossed to be 2 per apex seal. It would be nice if Tower had them by mid December but I suspect that is not real - I guess I can ask them to email me.

I only know of one guy running one in this part of the world. I believe he was quite successful with it. I have read plenty of accounts of bad experiences too. There was a sugggestion that tolerances from new were a bit variable and so some ran well and others not at all. Wear was a common problem leading to no compression. Also cooling was critical along with oil to try to prevent the springs losing their temper.

If I can make this one run a few time on the bench and maybe fly it a few times then put it on display I would be happy. I repair and re-build a few old glow, diesels and spark engines for fun to then put on display. I fully accept getting the wankel running may be an exercise in futility.

Thanks
Tarquin

I suppose this is a long shot, but you might be able to make them out of steel strapping or other similar spring steel.
I modified an FS30 to water cooling last winter and it worked fine for a short time. Then refused to start with fuel spraying out of the carb. The problem was a broken intake valve spring. I was able to find something similar albeit with a softer spring rate and it has worked perfectly since. You have nothing to lose by attempting to make your own parts.

I think I have some sets of them. I will check tomorrow ok.

I have two packs of them. If you really need one ASAP and cant wait on tower then let me know. RE 49-PI Seal Spring 41807004

I have owned a Gen 1 and a Gen 2. the Gen 2 ran much better and seemed to over heat a bit less. I need to do a few more runs on mine however.

I would have thought it made more power than that. The OS 25 FX turns a APC 9x6 at 14,000 on YS20/20 fuel. Yes I know its more nitro but always thought these turned 18,000 or so on a 9x6.

That was the first run of an engine of unknown usage. It might turn a higher RPM but I was not willing to try on the initial run. Besides I do not want to destroy my gift.

Yeah no worries, I haven't seen any videos where people ran a 9x6 and showed the numbers. I have two brand new ones and have to figure out a plane to put them in

Are yours Gen 1 or Gen 2? The Gen 1 engines run really HOT. The Gen 2 are a bit better. Personally I would only install this engine on an open nose airplane with PLENTY of cooling air to flow over it.

The video is a good reminder why analogue tachs are easier to read for model engines.