BMW R1150

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photocopter

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Sep 17, 2015
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garden bay bc canada
They are relatively heavy at 80kg according to this site.

http://www.takeoff-ul.de/
If you compare the rotax 912uls and the BMW R1200 weights it's about 10Lbs difference. The rotax 912 uls with EVERYTING installed weighs between 165-187Lbs
The BMW is about 176Lbs all included > I'd like to ad that the BMW parts are esy to get (every city has a BMW agency) and a 'million' times cheaper...
Also the BMW is much less thusty.
 

Air Trikes

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Joined
Dec 21, 2015
Messages
40
Location
Montreal Canada
I can't say I'm a serious BMW conversion specialist. I have built only 4 BMW R engines by myself (comparatively with 70+ Suzuki), and 30+ have been built by my customers using SPG conversion kits. The picture below is my first with SPG-2 R1150 scaled. The weight was 72 kg (159 LB) no muffler and oil.
We can discuss which engine is better, BMW R or Rotax 912. I fly different aircraft with Rotax 912 ULS, Suzuki G13BB, BMW R 1150. Each has their pros and contras. My feeling - injected BMW and Suzuki are more reliable and easier to operate than carbureted Rotax 912S, especially in cold weather. Videos of aircraft flying with BMW converted with SPG gearbox systems
 

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dino

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Sep 18, 2007
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658
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florida
If you compare the rotax 912uls and the BMW R1200 weights it's about 10Lbs difference. The rotax 912 uls with EVERYTING installed weighs between 165-187Lbs
The BMW is about 176Lbs all included > I'd like to ad that the BMW parts are esy to get (every city has a BMW agency) and a 'million' times cheaper...
Also the BMW is much less thusty.
I think most people would not want "everything" such as the extra alternator on their 912S. Comparing weights is difficult at best. The gold standard is comparing weights of two otherwise identical aircraft with different engines installed. I participated in the assembly of 2 Aventura amphibs. 1 with a 912UL and the other with a TakeOff BMW. I don't recall the exact weight differance but it was more than 30lbs. Note the 912ULwithout slipper clutch is lighter than the 912ULS.
 

photocopter

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Sep 17, 2015
Messages
27
Location
garden bay bc canada
I think most people would not want "everything" such as the extra alternator on their 912S. Comparing weights is difficult at best. The gold standard is comparing weights of two otherwise identical aircraft with different engines installed. I participated in the assembly of 2 Aventura amphibs. 1 with a 912UL and the other with a TakeOff BMW. I don't recall the exact weight differance but it was more than 30lbs. Note the 912ULwithout slipper clutch is lighter than the 912ULS.
Interesting thought but I believe that two identical aircrafts never weigh exactly the same. Cockpit layout, wiring, paint thickness, fabric covering, glue thickness etc.. makes it nearly impossible to have the same aircraft model come out the same weight. I believe the best way to know the installed engine weight package is to unbolt the engine from the firewall, still in the engine mount with everything installed to make it work and weigh it...
My 2 cents
 

Air Trikes

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Dec 21, 2015
Messages
40
Location
Montreal Canada
I think most people would not want "everything" such as the extra alternator on their 912S. Comparing weights is difficult at best. The gold standard is comparing weights of two otherwise identical aircraft with different engines installed. I participated in the assembly of 2 Aventura amphibs. 1 with a 912UL and the other with a TakeOff BMW. I don't recall the exact weight differance but it was more than 30lbs. Note the 912ULwithout slipper clutch is lighter than the 912ULS.
I often repower aircraft from Rotax to conversion engines. Mostly Suzuki G13BB but it doesn't matter. When you have the aircraft with Rotax, and then the same one with BMW (Suzuki, Honda, Subaru etc.) then you can estimate the difference.
We have to compare MPFI engines (BMW R1150-1200 or Suzuki G13) with MPFI Rotax 912 IS with additional alternator. The weight difference will be not more than 15 lbs I think.
 

xwing

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Joined
Nov 4, 2019
Messages
77
First i'm hearing about going with a centrifugal clutch, or the need/reasons with a BMW twin here.

All i found with a quick search "allow the engine to idle without load from the prop" which can also minimize idle running vibration issues for 2 strokes.

Don't think hks uses one? Maybe cos smaller engine?
http://www.hksengines.com/technical-info

What clutch is used with SPG? I assume there is service history out there? Expectations of no issues to TBO?
 
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Air Trikes

Active Member
Joined
Dec 21, 2015
Messages
40
Location
Montreal Canada
First i'm hearing about going with a centrifugal clutch, or the need/reasons with a BMW twin here.

All i found with a quick search "allow the engine to idle without load from the prop" which can also minimize idle running vibration issues for 2 strokes.

Don't think hks uses one? Maybe cos smaller engine?
http://www.hksengines.com/technical-info

What clutch is used with SPG? I assume there is service history out there? Expectations of no issues to TBO?
Yes, you are right, the centrifugal clutch is used to minimize low RPM vibrations. Here is the picture of SPG-4 gearbox for BMW R1200 with the clutch. This clutch is used together with a rubber donut. Centrifugal clutch + rubber damper = smooth running engine, you can see it at a video from my previous post. I was converting BMW engines without this centrifugal clutch. I can't say it is impossible. We tried to use heavier flywheels, stock friction coupling with spring damper. I can't say it is impossible but we had to use lower ratio gearboxes and lighter smaller diameter propellers.
About TBO for the clutch. The design of the pads is similar to car drum brake pads. If you use brakes often, they will be worn out faster. The same for the clutch, if you run the engine going from 1500 to 2500, you worn out the clutch pads faster. I would inspect the clutch pads (together with the rubber damper) in 300-400 hours, then every 100-200 hours depends on their condition. It is not difficult or expensive to order and change the clutch pads or rubber damper if necessary.
 

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cblink.007

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Jul 7, 2014
Messages
147
Location
Texas, USA
Maybe because BMW dont want there engines in airplanes?? just look at the electronics on a 1200 GS and the way they incorporate all functions into 3 on board computers. very difficult to convert because everything from engine mapping to turn signals feeds off these three units.

Than call Rotax and tell them you want to buy a C drive to convert for a BMW engine and see what they tell you...

Some grim days ahead for guys who just want to go flying... my 2c
We took a very close look at doing an R1200GS in lieu of a Rotax 912, but we ran into alot of snags.

1. Modifications to the electrical and lubrication system were required.
2. No BMW Motorrad-affiliated shops would assist us due to legal liability, as the engine was to be used in a manner inconsistent with its design.
3. No factory warranties or factory technical support was available due the aforementioned legal liability concerns.
4. Insurance would be higher, because it is not an aircraft engine.
5. The engine, after mod work, would be slightly heavier than the 912.
6. The engine, after modification work is done, would come in at a price point similar to a mid-time 912.

At the end of the day, due to several factors besides our mentioned points, we elected to stick with the 912. It is an aircraft engine with a great support network, and warranties are offered among other perks.

That being said, I'd love to hear successful BMW stories!!! I'll dig around our computers; I think we still have plenty of BMW documents and 2D drawings, and if I do, I will gladly offer them here for download!
 

Maxim

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Aug 29, 2019
Messages
5
If the file are available for download, please share with the community like a dropbox or google drive link. Im very interested in that files so far.

regards Max
 

Maxim

Member
Joined
Aug 29, 2019
Messages
5
=simple,good Centrifugal Clutch with rubber dampfer=

circa 1 kg weight,many sesones work, <100 HP !
Is that clutch running so far? How is the conditions with that unit and the BMW engine?

regards Max
 

sming

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Joined
Apr 10, 2019
Messages
60
A french company is selling what's looking like a nice BMW package (custom ECU) for pusher configuration (trike & autogyre) : Moteur VENTURA R1200S 3500€ for the PSRU though...
The german version: Take Off
 

Maxim

Member
Joined
Aug 29, 2019
Messages
5
I known that Company, is the same like TakeOff. As the Yahoo-Groups was placed there was a Group called MotoAir with a couple of guys that bring this engine in the air, I do not counter how many times They use the standard ECU but dual with dual injection unit and dual ignition too. All times use a Rotax gearbox C.
 
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