Drifter Conversion to Rotax 912

Does anyone know how big a job it is to convert a Drifter from a 2 stroke to a Rotax 912?

I know there's a fair few that I've spoken to, who don't reckon the 912 Drifter is a good idea, too much weight and they said the extra power beyond the 582 doesn't provide any real benefit, given the dacron wing.

I loved my SCSI WB 45hp Drifter and it certainly would have benefitted from more power but the extra weight of the 912 and consequent more weight of front seat ballast - unless you're a very big fella/gal (in which case maybe get a 701) - exceeds the wing's optimal capability.

To answer your specific question, there is/was a bolt/rivet-on kit to convert them with basic tools. I also recall that several people who converted theirs, unconverted them later and went back to the 582, so if you're really determined maybe you could advertise to find someone who wants to sell the parts.

Thanks for that, I was originally thinking 4 stroke reliability but the 2 strokes now days seem to be faultless.

We have a 912 80 hp and to be honest it is terrific, couldn't go back to the 582. however the cost is huge, not only the engine but getting it certified to fly. If you have lots of cash to spare go for it. 

Thanks for that advice, no surplus cash here but any rough idea what amount of cash I would need to have?

The 80hp is what I had in mind originally.

You could get away for under $16k  with a 2nd hand engine maybe.  dont know if the engineer costs have gone up since we did ours. 

I understand the only Rotax two stroke available new is the 582. That's the common engine for the SB version. The WB seems OK with the aircooled 503 but you will have to build up a good one yourself from perhaps a couple or more old ones, in the future. The Rotax 912 time expires on years (legally) and the original 80 HP is the most reliable. Some versions don't have the trans clutch and some had starter drive issues. Some break the crank near the drive end. No motor is perfect and power for weight and price the 2 stroke is way ahead..  Nev.

There is really no practical way to convert a 2 stroke Drifter to 912 power. You could use the wings, provided that they had the certified spars and flying wires, same with the tails. You will need a new longer boom tube and pans, the pilot seat has to be moved forward to balance the extra weight of the engine, the fitting on the boom that attaches the down tube from the rear spar is wider to attach the new engine mount, the boom is internally doubled under that fitting.

Not worth the effort.

sorry rotax618 no to most of what you have quoted this is fully certified without both with CASA and RAus. without those mods.

cheaper and faster to buy a used lockwood super drifter

I watched Wayne Fisher build a number of 912 Drifters, and helped rebuild a crashed aircraft. The lightweight Maxair 503 wing is not strong enough for the increased weight and performance, you could put sheets of lead on the pilots seat to balance the extra weight of the engine, but I hardly think that would be acceptably. The pilot provides the balance weight on a pusher aircraft So how do you get the Weight and Balance of a pusher correct if you add 35 - 40 kg more weight to the rear of the wing? The weakest point of the Drifter boom tube is directly under the down tube from the rear spar, early Drifter booms cracked there, it is subject to the greatest bending moment when landing or taxying, being 1/2 way between the UC and the tail wheel. Wayne sleeved the boom there because of that.

Sure bolt a 912 onto your Drifter if you like, but if you don’t take into account the extra stresses and the CG the results will be catastrophic.

 It's a point I checked before every flight. I think a lot were beefed up there.  I speak of the SB  the WB was lighter and happier with the smaller motor and flew ok a bit slower.  Nev

rotax618 I agree with some of the above and yes the boom should be strengthened dont know enough about the Maxir 503 wing but the Ausflight WB 582 wing according to our engineer, is quite capable of the increased weight and performance  also the weight and balance does fall in the new guide lines we have an increase MTOW. Having said that yes if the pilot is a light weight you do need weight on the seat. We had to jump through alot of hoops both from CASA and RAus to get a full certification. all of which was scrutinised twice once by our engineer and again by an RAaus appointed engineer mainly because we where the first mods under the new MARP and we had to prove the concept. As a side note the SB 582 is not suitable for a conversion ends up being too heavy and exceeds MTOW. and I really do agree with you everything you do to an aircraft you must do your due diligence and make sure that what you are attempting is safe.

Yes the Austflight WB 582 wing is certainly strong enough, it is the certified wing I was referring to, conversions of Amateur Built 19 category lightweight Drifters is not possible.

 The 618 didn't develop any more Power than the 582 as far as I know , and was not as reliable. It's also a bit of an orphan, isn't it? Nev

That is not true, the 618 produced far more power than the 582, and would spin the same prop 1000revs more,  it was in direct competition with the 912 80hp. The 618 was heavier than the 582 and all of the extra weight was in the crankshaft. The 618 was a de-tuned 670 which produced 107hp. The RAV valves were poorly understood by users and required an additional manual control to exercise them after warm-up and to lift them at density altitudes above 5000ft, also the carbs required different jetting berween the PTO and MAG carbs. The muffler was also larger than the 582. If you understood the the above the 618 was unbreakable and long lasting and the most power for weight.

The 618 was 75? Hp  due to the power valves, good on a kart or bike where they open and close often keeping them free from carbon.

Keep up the discussion fellas, there's plenty here to digest and it is exactly what I needed to assess things.

I have never flown a drifter but I have respect for them. Would I want a 912 on my Thruster, no, it would be pointless, the 582 is perfect for this class of aircraft.

Thruter88 - Its a similar issue to that faced by trikes - why in terms of performance - do you NEED the power of a 912 vs a lower power/lower weight two stroke?

For me the EclipsR with the 80hp 912 only really comes into its own when I fly solo and put the ferry tank on the back seat and the camping equipment under the skirt - I get full camping gear and 9 hours + reserve fuel on board and remain within the 415kg MTOW ... weight saving on a two stroke would not give me the same 9 hours fuel - I'd only have 6 hours + reserve. 

The reason factories stopped using two strokes is the market place for new trikes - sorry but 65+ yo students learning in 912 powered aircraft - fuel cost is a big issue for schools - will never look at a two stroke so they are on the way out... same reason newer trike never live with their wing in the bag and sit in hangars under full tension in the wing - that's shortening the life of the wing frame and probably keeping the skin a bit less scuffed but I'd hazard a guess than many older trike pilots who took up the aircraft later in life actually cant rig and de-rig their aircraft.

Now when it comes to re-engining an older airframe the real question - provided its not a certified design - is whats available and how adventurous do I want to get as a the designer/owner.

This thread might be talking about type approved airframes and the initial question is of someone looking for a not-too-adventurous approach to conversion.

If you’re wanting to get away from 2 stroke is a 1/2 VW a useful

alternative?

Does anyone know how big a job it is to convert a Drifter from a 2 stroke to a Rotax 912?

Thanks mate, much appreciated.