BMW R1200 as alternative to VW or 1/2 VW ?

[wojtekseta]

BMW R series are very popular in Europe for noncertified aircraft as replacement of Rotax 582 or even 912.
In comparison with Rotax 582 BMW R is heavier, more powerfull, much more economical and have much longer TBO. If you plan to build long range airplane the instalation of BMW R with less fuel consumpion (smaller tanks, less fuel, air/oil cooling) will be much lighter than 582.
In comparison with Rotax 912 - they have similar parameters, except weight . BMW R with redrive, original harness, starter, alternator, computers etc. weihts over 80kg and is heavier than Rotax 912.  Builders who have a LOT of many chooses Rotax. For others - BMW R family engines are, in my opinion, second choise.
All instalations BMW R engines I saw in light aircraft uses redrive.
In USA are very popular conversion of aircooled VW without redrive, and I'm sure in the same way we can use BMW R - particullary R1200. The engine is in production from 2004 and differs from olders - have bigger displacement, lower weight and - what is important - balancing shaft. It have four valve per cylinder, geometry 101mm X 73mm and compression 12:1. Full throttle is about 100HP at 7000 rpm. Without redrive we cant use so High rpm. For our purposes most important is torque curve - allmost flat in range from 3500 to 7000 rmp. At 3600 rpm (where are the VW have highest rpm) whe have over 100Nm (74 lbf*ft). The power should be about 52-55 (European) HP. You can see it in attached curves.

To be continued.

[wojtekseta]

Last year I decided to try this idea. I bought used R1200GS engine with all sensors (crankshaft sensor, 2 head temperature sensors, knock sensors, oil temperature and pressure sensor etc), 4 spark plugs, two integrated ignition coils (I have to buy two more, to have dual ignition). The engine has about 60000km, great compression and does not have bigger cracks. All this weighted 49 kg (106lbf). You can see it on the picture - price $500.

Sooner I build, programed but not tested ignition module for full or half aircooled VW (Leburg was my inspiration). Parts (without my time of development) costed maybe $10. I ordered proppeler hub, sticked on it 2 magnets in opposite positions for driving Hall sensor and just bolted in place of original cluch. Magnets are additionaly secured with glass rowing and epoxide resine. Hub is slightly massive, because partially working as flywheel. Price was about $50, because it is very simple and made from two flat discs and tube of black steel, welded and turned together. Hall sensor is located in aluminium tube, and mounting in place of original starter ($2).


After that I bought  two cheap, chinese carburators for tunnig scooters. Price for two was $50 with transportation.
I looked on dismounted similar engine and found that it have huge main crankshaft bearings - one of them working as linear bearing and should without problems manage with engine thrust.
Engine have a few very strong mounting holes - you can mount it on many ways. In motorbike the engine works as central part of frame. I used two holes (lowest) to bolt the engine to the temporary mounting frame. The frame is part of my TIG welding trainnig.

To be continued...

[wojtekseta]

Next I made block of light wood (wood bar dyno) as propeller and balanced it. If I good remember block dimensions are selected to simulate load of 58HP at 3800 rpm. I made some steering and "fuel system". Carburators was set without any instruction, ignition programmed acording to Leburg ignition curve.



The wooden block is quite short, R1200 has giant compression, all that was never tested in practice. But after 15-20 turnings engine started to work. And this 20 turnings was all what I can do this day (and 7 next days)  .


After that I made few more test, but some technical (not difficult) and health problems stopped my work (to start the R1200 engine you should be strong ).

Last time I turned back to BMW. I made some exhaust, projected and programmed modification of ignition module to work with original inductive crankshaft sensor (not tested in any way, but after some test should to work). It will be main ignition, secondary will be with Hall sensor.

To continue my tests I have to do:
- aluminium intake collector. I'm going to use one carburator, with heated intake. Now I can't adjust carburators because of rotating block.
- test new ignition
- stronger test stand
- made plate for alternator coils (single ignition draws only 300 mA at 4000 rpm - the engine could work only on baterries, but add alternator is very easy)

If you are interested in some part of my work please write in this topic - I will try to help.

And please help me with my main question from this topic https://www.eaglersnest.com/forum/index.php?topic=1523.0 . If R1200 will be to heavy I will have to built BetterhalfVW,
Once again sorry for my English, but I hope you will understand my writings.

[Dan_]

BMW article on page 16...  To say nothing of the 3 liter VW engine.


http://www.contactmagazine.com/Issue80/Issue-80L.pdf

[wojtekseta]

I met the author (Kuba Myśluk) 11-12 years ago and I flew as student on CH601 with his BMW R1100 convertion. He is known in our part of Europe as BMW convertion enthusiast and specialist. Problems he described are with redrives and its clutches. Woodden propeller directly on the crankshaft should dampen vibration as in 1/2 VW.

[wojtekseta]

After some improvements I started R1200 today. It has single 32mm OKO carb with changed to little bigger main jet (1,4mm), fiberglass intake (outside ugly, but inside quite smooth), modified ignition (still Hall sensor, but with possibility to comunicate and tune via bluetooth). Engine started after second pull, runs smooth, but on default ignition setings reached only 3200 rpm. I leave it on the max rpm and changed igniton advance 8 deegrees more (total 30 deg). After that engine reached 3500 rpm. You can see it on attached graph (I can log ignition by bluetooth). Wood bar dyno was designed for 50Hp at 3600 and about 97Nm of torque (block diameter 821mm with x-section 55mm) . 3500 rpm means that R1200 reached about 46HP and 93Nm. I burned out about 0,7 liter of fuel in one 5 min run. Sparkplugs looks clean, cofee with milk colour. Engine not reched the temperature to turning on the termostat (outside temp was 25 deg C, 77 deg F).
It was a only one try because of neighbours - I'm sure R1200 can reach more .

Wojtek.

[scottiniowa]

I know this is a world wide forum, but have to ask, are there these BMW engines available in the USA?  The progress looks great, but I don’t like going where no man has gone before, unless I am 100% for sure of my new direction.  In this case with the engine, I would not be unless I found a few others that are getting along super well.

Sure looks like a great motor.

cheers

[wojtekseta]

I'm sure You can buy it in US without problem (used or new). Used you will find on ebay in $1000 (I bought my for $500 in Poland). You should look for BMW R1200RT, R1200GS, or R1200ST manufacturing years from 2005 to 2013 (they call the engine "hexhead"). In the USA were sold at least tens of thousends of these bikes (https://www.asphaltandrubber.com/news/bmw-r1200gs-top-motorcycle-usa/).  The engine is lighter and more powerfull than previous versions. Additionally the engine has got dual ignition and balancing shaft. From 2014 R1200 has integrated gearbox and is watercooled (is to heavy for us).
BMW bikers reports that engine lasts for 200.000 miles or even more  . How many flying ours is it?

[Dan_]

I know the fellow in the video...  He sold the plane shortly after he published this video.


I think he had 200 hrs on the BMW engine at the time.  


I doubt an airplane will ever make U.S. part 103 weight with the Beemer motor however...

[wojtekseta]

I know the fellow in the video...  He sold the plane shortly after he published this video.


I think he had 200 hrs on the BMW engine at the time.  


I doubt an airplane will ever make U.S. part 103 weight with the Beemer motor however...

I have doubts too. I wrote about it in https://www.eaglersnest.com/forum/index.php?topic=1523.15 . But it looks like it is possible. 
BTW The engine from the film is about 58-60lbs heavier than mine.

[Dan_]

I have doubts too. I wrote about it in https://www.eaglersnest.com/forum/index.php?topic=1523.15 . But it looks like it is possible.  
BTW The engine from the film is about 58-60lbs heavier than mine.

10-4... 

He was running the Rotax C gearbox and no telling what flywheel --probably stock. 

I am not familiar with the differences of the different model engines.

If you would like to email him send me a PM, he gave me his permission... 

He had success with the BMW and may have info you can use.

[Jaydub]

I know this is a world wide forum, but have to ask, are there these BMW engines available in the USA?

They are sold in the USA and you can find these engines used on ebay and other places.  I've ridden BMW motorcycles since the 80's.  They are quite reliable and smooth.

I've heard the power pulses are too great on these but cc wise they are similar to the larger 1/2 VWs.  They are a larger bore and shorter stroke than the VW (Bore 101 mm x 73 mm stroke) with 11:1 compression ratio.