1/2 Rotax 912

[fly_tornado]

https://www.youtube.com/watch?v=RVfbUfPHbpU

 

 

 

[kasper]

Interesting to see the Romanians do what Rotax started with - a boxer twin 4 stroke.

 

Most people forget or never knew the origin of the 912 was a boxer twin that looked pretty much exaclty like this ... but the rocking couple of the flat twin was not acceptable to Rotax and they used the twin to create the first 912 flat four.

 

Wish them well  ... but at only 50hp I think thay have really limited sales ... a big bore kit to get it up to 65hp+ AND give it a bed mount option to direct bolt replace a R582 then you will have a larger market.

 

 

[spacesailor]

The 1/2 VW has gone to flat bed installation too. more HP too. spacesailor

 

"

 

 

 

 

 

 

[Litespeed]

Looks a much better version.

 

Like the 50 HP.

 

 

[spacesailor]

I would like a 1/2 McCulloch motor. two stroke . two pot, about 1.5litre.

 

Would be smoother with-out the rocking motion of the four stroke.: 90hp or the 75 hp,

 

spacesailor

 

 

 

 

[kasper]

12 hours ago, spacesailor said:

 

I would like a 1/2 McCulloch motor. two stroke . two pot, about 1.5litre.

 

Would be smoother with-out the rocking motion of the four stroke.: 90hp or the 75 hp,

 

spacesailor

 

Which half would you like?   The McCullough flat four pressure sumped  with opposing piston sets - it is a two pulse engine. A half McCullough would be an in-line twin not a flat twin ...

 

 

[spacesailor]

WHY not a flat twin, Same as Vw & many others.

 

All depends on the crank:ie lump in the middle.

 

Why a Sump on a two-stroke,? No oil in there, sometimes a seperate oil-tank, but a sump of oil !.

 

spacesailor

 

 

[kasper]

The McCullough front two pistons go in and out together and fire together ... that’s the only way to get the pressure sump and transfer fuel/oil/air into the pistons.  Like the r582 it’s disc controlled from the single carb over the centre of the engine.  If you wanted a flat twin McCullough you’re effectively getting a single power pulse each revolution.

 

if you take both pots off one side and leave it as an inline twin you get the same power but two power pulses each revolution - a much smoother engine.  

 

 

[kasper]

If you want a flat twin two strike with two power pulses you’d need to either run two sumps or have a blower to pressurise the single sump. 

 

Or get really adventurous and us and go for a flat 4 two stroke with stepped pistons and a wet sump. 4 power pulses each revolution and simple plain bearings without the oil in fuel environmental issues of most two strokes.  

 

 

[Job CF]

An enquiry made earlier today revealed that they won't be producing or selling these engines.

Instead, "They want to sell the concept, the idea including all drawings" for €30K.

Since the price of the R912 is around 10 times that of a VW, commercially it is a non-starter.

 

 

[440032]

One-off Jabiru 1100 twin 40hp was running at Wagga in 2006. It never flew in the airframe that it was fitted to. (Shook like an angry mother!)

 

 

[Thruster88]

One-off Jabiru 1100 twin 40hp was running at Wagga in 2006. It never flew in the airframe that it was fitted to. (Shook like an angry mother!)

 

That is interesting, I flew a Thruster once that was fitted with a BMW twin opposed driving thru a rotax C box, vibration was low like a 582. The gearbox would help giving more power pulses per prop revolution ?

 

The HKS twin was tried on the Thruster in the 90's, don't think it was successful. The HKS is still in production and looks good on paper, anyone have any experience?  

 

[fly_tornado]

HKS went out of production after Fukushima when electricity prices spiked, I think its finally died now due to a lack of suitable airframes

 

 

[Job CF]

That is interesting, I flew a Thruster once that was fitted with a BMW twin opposed driving thru a rotax C box, vibration was low like a 582. The gearbox would help giving more power pulses per prop revolution ?

 

The HKS twin was tried on the Thruster in the 90's, don't think it was successful. The HKS is still in production and looks good on paper, anyone have any experience?  

 

[ATTACH]41342[/ATTACH]

 

" As of June 30, 2019 the HKS 700E is no longer available as a new engine. A limited supply of spare parts is available, and we will continue to provide these on our store as long as supply lasts."

http://greenskyadventures.com/hks-engines.html

 

 

[spacesailor]

My mate has one, New, never fitted to his HummelBird, (another dead plane by Bureaucracy ).

 

He built a 1/2 VW motor with a home chopped prop, that sounds good.

 

He bought a Lightning VH.

 

Not visited for ages now.

 

 

[Downunder]

An enquiry made earlier today revealed that they won't be producing or selling these engines.

Instead, "They want to sell the concept, the idea including all drawings" for €30K.

Since the price of the R912 is around 10 times that of a VW, commercially it is a non-starter.

 

I think if they had of gone the other way with a 6 cylinder it might have been more successful. 

 

Atleast someone with a 912 could "bump" it up to the 6 cyl.

 

6 aftermarket barrels and pistions with 2 extra heads and some other bits and pieces.

 

Definately fuel injection.

 

I think the gbox would be strong enough, atleast for 1000 hrs....

 

 

[Downunder]

I really see this 1/2 912 as dead in the water.

 

They don't even show it swinging a prop or in a flying aircraft.

 

As stated it's underpowered. Big bore aftermarket barrels/pistons would be cheaper to buy and give more power.

 

Do you buy Rotax parts to fit it out? That would cost the price of a new 912 atleast.

 

Do you strip an old 912 for parts? Complete and running "out of hours" 912's still have good value so you'd be destoying that. 

 

In 2019 it should be fuel injected.

 

The 912 gbox would be far too heavy and would probably need a custom ratio anyway. Why didn't they use a 582 box or even a 503 which is 50hp...

 

I do see merits in a semi-clone set up. Taking the heads for example and cam, oil pump system but other parts/systems can be done better and cheaper.

 

 

[facthunter]

Vertical twin two strokes once they get larger tend to have vibration problems due the offset of the 180 throw crank. The opposed two stroke has to fire the cylinders at the same time if it shares the crankcase. Similarly a flat four or a conventional in line four. Anytime you have more than one piston at TDC together. 

 

      A step piston or (positive displacement blower). 3 cyl radial Two stroke would have the smoothness of a four stroke six and have a separate oiling system. ALL 4 stroke radials have uneven cylinders in each bank.  Long crankshafts get more torsional vibration problems (harmonics).  and are heavier..

 

  A V4 may be a reasonable compromise with an added advantage of not having all pistons stopping at any one time. and easier manifolding and very rigid cylinder block,, (narrow angle) Nev

 

 

[kasper]

Vertical twin two strokes once they get larger tend to have vibration problems due the offset of the 180 throw crank. The opposed two stroke has to fire the cylinders at the same time if it shares the crankcase. Similarly a flat four or a conventional in line four. Anytime you have more than one piston at TDC together. 

 

      A step piston or (positive displacement blower). 3 cyl radial Two stroke would have the smoothness of a four stroke six and have a separate oiling system. ALL 4 stroke radials have uneven cylinders in each bank.  Long crankshafts get more torsional vibration problems (harmonics).  and are heavier..

 

  A V4 may be a reasonable compromise with an added advantage of not having all pistons stopping at any one time. and easier manifolding and very rigid cylinder block,, (narrow angle) Nev

 

V4 stepped piston engine for UAVs developed in the Uk ?? by Bernard Hooper engineering. 580cc looks lovely but they do not appear to be looking at aircraft engines