Rotax install near complete

So I am basically at the point now where I have run out of things to work on. I have the cowl up to a point where I need to fly it and see if anything needs changing.

My biggest hand brake now is I am waiting on a prop. I actually thought I was going to take a lot longer than this but I have been working on it every spare minute since the 20th of February. I have even taken it out and given it a good wash as the dust build up was depressing. I have ordered a prop from Sensenich and will be using the Sonex recommended Rotax prop. It seems I am going to be the first person to use this Plane/engine and prop combo so it will be interesting to see how it goes. I had plans to just use a Bolly prop from our local guys but I wanted to keep the thing simple and also this way I don't need to use a large spinner which would restrict my air intakes and so on. I plan to use the same Sonex spinner and hopefully it will work well. Time will tell.

I have carried out a weighing of the aircraft this weekend and found it to be very close to what it was before. In fact it has actually 1x kg heavier than with the Aerovee turbo. Well I do have an aux tank fitted now also but to be honest there is not much difference in the final installed weight with the two engines. I was actually very shocked myself. I am very happy we moved the engine forward as much as we did as I think it will fly really nicely and hopefully the exact way it did before. I was very happy with how the Turbo flew and hope this one is just as impressive. It will be a great comparison when I do get it flying as I don't think anyone has gone from a Turbo to Rotax yet. I have tried to find data online about how the Sonex goes with a Rotax but everyone has a different prop and so detailed info is very sketchy.

I have just completed the annual inspection also this last weekend past with nothing untoward coming up. It was also a good time to fix those few things that were bugging me like the cable for the Aux tank and just re adjusting the elevator trim and those little things.  I do need to wait also on the paper work to come through but until I have a serial number from the prop I am going to use I am stuck dead in the water. I am really hoping it will come soon as the winter flying season is just coming into play. Summer is still very flyable up here but it does tend to get very hot, turbulent and sometimes just plain not fun. Winter up here generally consists of nice warm days with light winds and clear skies, unless a front comes through, but like anywhere we pick our days to fly.   I have been in contact the whole time with my AP inspector and things are looking good.  I have that massive plank on the front of my plane called the GT prop. Its a nice enough prop but just not really suitable for what I am after. It's a bit big in diameter and a little light on pitch. I have not changed my gear legs or anything, nor added larger tyres. Everything is as before.

 Oh except the engine :)

It has taken me 3 months to do this conversion so far... I have had lots of help along the way and really couldn't have done it so quickly or even so well without all the guys efforts..

Thanks to all who chipped in...

It's not over yet though guys,,,don't run away,,,just in case...... :)

Oil tank and lines

The oil tank has been one of the easier aspects of the installation. I needed to have it vertical for in flight operations so its on an angle in the 3 point attitude. I have tried to get it as the manual says and have the oil level half up the tank equivalent to about the same on the engine sump... Something like that anyway. I tried to get it as close as possible. I have also mounted it as such that I can adjust it also if needed to tweek it if I find it necessary.  

I have replaced all the oil lines with new hose and so on throughout the system and generally tried to use pinch clamps where possible. As you can see I have tried to also fire sleeve every oil and fuel hose and also fire sleeve the majority of the wiring harness. The old plane came with a huge amount of thin fire sleeve suitable for just this so I incorporated it into the install. I had to buy a few meters of thicker fire sleeve but that's about it. 

Cylinder Cooling

I have seen many Rotax engine installs but not too many have had the cylinder baffling retained on the engine. I'm not sure why as it seems quite a good thing to have I would assume. Anyway it was on the old engine so I incorporated it onto my installation also.

I had to cut down the original ducting that pointed too far down and make a new air intake. This again was harder than first thought. It turned out okay in the end but again, luckily, the cowling hides the fiberglass work as it sure isn't the prettiest thing around.

Again starting from a duct plug I made from foam. I had about 4 modifications to this in the end and also I could have made it significantly smaller but it's on there now so that's that. I will fly it and see how my temps are but it will probably work okay.

Work in progress

 Filling in the gaps and attaching it to the original with glass.  This is also an earlier picture of the oil cooler duct. I had reshaped it to avoid cowling access issues and also narrowed up the nose to make it a smaller inlet hole and also line up with the centre of the cowl. Essentially the oil pump in the front mirrors the size of the inlet and that's how it is for now.

The final fitted duct with seals attached. Again not pretty but hopefully serviceable. Obviously I can't get the fuel pump off in this configuration so I need to make an access port slide arrangement. This will be easy as now I have a bit of a grasp on fiber glassing.

Water cooling

Now this is where it actually got really hard and I invested so much time on failed theories and I think at the end I was up to about plan E for getting this thing to fit and work. Honestly it took ages and I still don't even know it it will cool properly or even at all. I didn't realize until I really looked at the radiator that it actually had 3 of the 4 mounting pins broken off from the accident in the old plane. This bummed me somewhat again as now I've had to buy a cooler and radiator and suddenly the reasonable deal I got for the complete fire wall forward engine package was getting more and more expensive.   Still what do you do?    I was this far along the road I couldn't just stop now. So I bought this aluminum one. I found out later when I looked it has 1 x less core than the original one. I hope it will cool just as well however.

Mounted in the general area. It's still basically in that spot now with some better attach brackets.

Side view

I had originally planned to have the ducting attached to the cowling and mate these two surfaces up. I quickly found out however I could not accurately mate the two surfaces together with the vertical split cowling.  The aim was not to modify the cowling much so I have gone now for the fully fitted and removable ducting. It was much easier this way and I hope it works. The surround didn't go to waste anyway as I incorporated it into the duct.

 Making the plug for the duct was very time consuming again and it literally took me days and days to get it all to fit.

I started with just making one side of the duct to flow around the engine then I would add onto it  or trim to suit the fitment of the cowling. In the end it didn't need much of either so I glassed the other side in.

Taking shape on the engine and glassing it on both sides

The test to see if I had a uniform air pattern on the other side of the radiator. I attached a piece of string to a wire and placed it on the back side of the radiator in different spots while using the leaf blower to see how the air came out. The leaf blower basically could blow about the same as 90 kts forward air speed... At about half throttle it was the same of about 60 kts airspeed.

The duct is a bit of an ugly duckling but at least it will be well hidden inside the cowl and not seen... I have learnt a massive amount about fiberglass in these last few months and I'm sure if I was to ever do it again it would turn out much better.

Oil cooler, or should I say oil coolers

When I drilled through the oil cooler core with one of my trusty 1/8th drill bits, to say I was disappointed, was an understatement. I can't actually bring myself to say how I stupidly did that so I'll just move on.

These things happen so I thought momentarily about trying to weld it up or something then just imagined myself flying over a forest somewhere and thinking about it, I knew it just wasn't going to roll,  so I made my mind up and bought a different oil cooler and mounted it differently.

I had a go of mounting the cooler right up front but it didn't feel right and I also had issues of where I was going to put the radiator so I chose to go in the conventional spot of under the engine.  It probably would have worked well there but after I drilled through it that option was ultimately gone anyway. I didn't want to shell out another $700 us for the same cooler so I bought one from my local shop for $140 and set about installing that.

I actually, at this time, still didn't realize I had stuffed the core and had a go at fitting it underneath. It was all connected up in the end and when we went to go and bleed the oil system with compressed air we found the hole... I had a little sulk, actually I had a big sulk,  moped around for a fair while but some other guys helping me that day got me out of the sink hole.  We bypassed the cooler and actually had a first engine run that day.  I had forgotten all about the hole when I heard the engine fire up.  We didn't run it long with no cooler but at least we proved out the engine.

Sonex Rotax 912 first start

The cooler ultimately stayed in this basic position but I used a different core which was this one .

I set about making a foam plug so I could make a fiberglass duct. I actually had to modify this original duct about 5 times. I think it's pretty right now but when I do the flight testing I will monitor the temps and decide. Ground running so far indicate it will be fine. In fact it may be too cool in flight so we'll see. 

I used hydraulic AN fittings basically due to their strength and the fact that I had no worries about weight up the front. It fact I welcomed it somewhat. I didn't want to end up with a tail heavy plane and hopefully I won't either.

Exhaust system

I was a bit apprehensive about my ability to fabricate my own exhaust so again enlisted the help of our local Aircraft mechanic on field. He did an amazing job of welding it but I did manage to help out a reasonable amount too.

 I had a big issue trying to source the 1 1/8  piping that Rotax use for their straight sections of pipe so bought the more commonly available 1 1/4 pipe.

It was clear from the onset that we were going to have to completely make a new system as the engine mount basically only took into account the coolant hoses and starter motor access.  I'm super glad we chose to go the bed mount in design.  It made the whole installation significantly easier as I was to find out at a later state in the conversion.  

The original pipes, we found had a major impact on the cowling so we set about tightening the curve and welding the stubs closer to the flange. This helped significantly however the cowling still did need to be modified slightly. There is not much room on the lower section of the cowling so all in all it's a pretty tight fit when closed up.  As I had moved my engine forward 1" this also reduced the amount of room everything had. The irony of this install is that if I had not cut the cowling back to fit the Aerovee correctly it probably would have been perfect for the Rotax. I really didn't want to have to do a heap of cowling modifications so now the hub sits proud of the cowling somewhat but after I paint it red I'm sure it will look semi okay... Hopefully it wont affect the performance much, but who knows!  

We tack welded the whole system basically to make sure it fit before doing any final welds.  It actually came together very quickly and I think from start to finish all it took was 4 x hours work on a Sunday morning and it was complete. 

Since then I had to rearrange a few electrical items on the firewall. They turned out to be too close to some exhaust parts so I gave them a bit of extra clearance.  This was easy enough to do.  Actually if I was ever to do another Turbo Aerovee install I would also rearrange the items on the fire wall differently. It was okay how I had them but just for access and perhaps better cooling air flow I would change a few things.

Taking shape. At this stage we still had no idea about the rear exhaust attach but it was reasonably easy too once we set our minds to it.  

More tac welding at this stage.

 

It's not too easy to see here but there it is... All done and time for a beer...  The muffler does sit quite a fair way from the engine.  I will use the tabs on the side of the muffler to support it with some springs or clamps as such to hopefully avoid any cracks long term and generally just keep the mass supported.

I have been in two minds about adding exhaust wrap to the pipes and still haven't decided at this stage if I will use it or not. I have bought two big rolls of the stuff and have it sitting there. I have added the original muffler heat shield and that covers most of the muffler... It's just the pipes that are exposed now. There is a small spot near the fire wall that I think may need some but again, I'm not sure. I think the Turbo Aerovee really needed it as the turbo used to keep a large amount of heat in the area and tend to cook electronic items. It just doesn't seem very common practice from what I can see on Rotax's so I will need to ask around I guess.  

Brendan and Sheepy came over to do some quality assurance checks a few days later ..   Sheepy was happy with the work so we progressed onto the next stage of the engine install. 

I might ask Sheepy about the exhaust wrap. I'm sure I'll get an intelligent Baaahhhh