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

Engine mount finalization

After the mount was fully welded by our local (top bloke) L.A.M.E I took it home, took all the old paint off, rubbed it back, primed and painted it.  It did take a reasonable amount of time but it was so rewarding to have a mount that would work. 

I did look into buying a mount from Sonex but by the time I managed to get it into the country I would be looking at well over $4000 for the thing. It was not my first preference to make the mount myself but if I was to be able to afford this conversion then I had to be a realist and look for a more economical solution. 

I am so pleased how it all turned out. I can't thank the guys enough that all helped to make this possible for me. It was good to sit back and let the experience of the other guys play out, watch and learn how it all came to pass.

Swapping over engines

I have been working rather tirelessly on this conversion. Pictures never portray the hours of work involved with these things but hopefully if someone ever does follow this in the endeavour to do a conversion like this they will gain a decent appreciation of what took place.

I've been a bit worried about the plane being tail heavy when I finish so I have moved the motor forward about 22 mm or 7/8 " forward for you gunslingers who still use the imperial system. Hopefully with the weight of everything installed like the oil tanks, radiators and so on, plus moving the engine forward, it will enable to me to keep my existing long range Aux tank behind the seat.

The engine was test fit onto the jog just to see how it would attach to the original Aerovee mount.

For a while there I thought the mount may have been able to be incorporated into the new engine fitment. I did try to use bits from the donor plane mount and the original mount and do some sort of grafting onto each other but it soon became apparent that this was going to be a foolish idea and we needed to basically start from scratch.

We did keep the section of the mount that retained the landing gear legs and so on but all the rest was cut off and we started planning the new mount.

I bought a healthy amount of chrome moly tube and we set to work. The bonus of the engine being in the exact right spot enabled us to make the mount piece by piece and allow for the starter ,carbs, hoses and ancillaries, giving them ample room while sticking to the design plan we all agreed on for strength.

The last picture is the engine mount all basically tacked together before it was removed for final welding and painting. The actual engine attach points were retained from the old mount and the rubber bushings also used. It worked well on the previous engine so we stuck with that method.

And so it begins

Well I haven't been mucking around in regard to this conversion. I have had a bit of help for all the planning and so on behind it. We had quite a successful weekend and it's sort of in place on the Sonex.

The jig is basically there to keep the prop hub in the correct position as per the old hub. A friend had also made up some spacers I could use to allow the engine to come forward or backwards via shims and to be able to position it correctly for the weight and balance. We’ll see how that all works out. 

So it looks like the Aerovee engine mounts had actually worn through again. I am a little surprised,  after all the work we did making the mount square and running new bushes. Anyway that's now a thing of the past. We have some plans for the new mount so hopefully this will never occur again. 

The Donor Craft

Well this is where my engine is coming from. A plane wreak as such.

 It had a damaged wing from an accident and apparently they don't make the wings anymore. It got a bit hard so the insurance company sold it off ...and here I am now.

Like I mentioned before, I will miss the Aerovee, They have a distinct sound and I just like the way they run and feel when starting them and so on. It just feels like ..ahhhh, something everyone needs to experience!  When you're going flat out and honking it along they feel tough......

I will miss you Turbovee,  but perhaps I just was not patient enough to sort all the bugs out.

Well it's been an exciting time I guess.

It's been quite some time since I last posted I know but I have actually been doing a fair bit of flying lately. I have been doing a few Aero's here and there locally and have been formation flying with another club member also with his RV7.

I did have a big mishap in that time though which was a Rotec TBI failure in flight that almost had me making an emergency landing in a paddock! I was lucky is all I can say. Lucky that I had read a bit about what to do if they fail and also that I had an emergency fuel pump installed into the system in case of this exact situation. 
 I look back now on the event and can see the warning signs from that flight.  If I had paid better attention I would have turned back and also have saved my engine from major works required. I had been trialing Premium Unleaded and it also was a hot day. I had noticed from other test flights with Mogas that the Egt's tend to run a bit hotter and the engine actually runs a little leaner with the same settings just different fuel.  However I had also ignored the fact that, primarily over the last few flights, they had actually been starting to rise and I hadn't really noticed. It was a long term thing that, looking over the flight data from a few flights before, I now notice. The TBI was starting to block up and I was unaware.
So long story short I was travelling at about 2500ft on a very hot day, 2 x pob when the EGT's started to rise and of course along with the CHT's. As they passed 400f at full rich it also started to detonate badly. I switched the fuel pump on but no change. I started to then look for a paddock as it was only a matter of time I knew before the engine would quit. I pulled the fuel over ride and it started to just force feed it fuel at about 48 litres hour. It did run again, that was relieving, and I pulled basically full lean.  It was down to about 35 litres hour but running again and able to just climb. In that short time I was down to about 1000ft and was about to declare a mayday on the emergency channel but as it was now climbing again and I made a bee line for home.

We did make it back to base but the motor had roasted 2 x exhaust valves and 1 x rear cylinder was toast. We both had a beer on landing and thanked whoever that we made it home.

Anyway not to be too disheartened I grudgingly switched back to the Aerocarb after replacing two heads and the cylinder and was flying again in no time.

That was the day that I decided to go through the process of an Engine conversion.  I briefly considered a Jabiru 3300 but really, if I was honest with myself, I wanted a Rotax 912 through and through.

 I don't want anyone to think though that I didn't trust the Turbo Aerovee, really it's a testament as to how it held up yet still got me home after being absolutely roasted by the fuel issue from the Rotec Tbi. I saw temps of over 520f+ and it was still running strong. It was down badly on compression on 3 x cylinders as we limped home but with the turbo still going strong we barely noticed a power drop once I could get fuel back to the engine via the over rides.   

I think the decision was mostly made as I have just had a guts full of working on the engine. I have lost count of  how many engine mounts I had changed due to the mount being incorrectly made from factory. They are going okay now (the engine mounts) but I think the Tbi failing was the last straw.  

Since the engine rebuild I have done, at a guess, around 20 + hours. The last flight I had though was a ripper and couldn't have ended on a better high.  Our Aeroclub went out for a fly away lunch with 7x  planes and 14 x people. A great day was had by all and the Turbo Aerovee went like a song. I think I averaged about 130 kts each way as I was pushing it quite hard to try to beat some other planes that I got the jump on, although a Rv7 and a Cessna 400 beat me back, but hey, I gave it a try  :)  

I will miss the distinct sound the Aerovee makes and I think so will a few others in my Aeroclub. I feel the Turbo really makes them sing and I feel a bit disheartened I have given up just as I think I have gotten on top of it, but them the breaks.  Time for a new chapter.