Building the new Bushbaby SAFARI

[KFA]

Too much power is just enough If it fits under the cowl, it's too small

[Oupa-G]

KFA I agree , one can always reduce power.

Cheers Oupa-G

[Jean Crous]

Too much power is just enough If it fits under the cowl, it's too small

As that arrogant cat, Garfield , says : "too much of a good thing is WONDERFULL "
I agree with KFA and Oupa-G

[Dobbs]

So when is the banana boy coming to collect his plane???

[Oupa-G]

My holiday is over and back to the Fairest. Hope 2011 will contain some paperwork so that I can complete the Bosvark. It is ironic that the paperwork time is exceding the build time. Some how that does not make sense. A mod based on a proven design. Will report again from Durbanville.



Cheers Oupa-G

[Oupa-G]

Back from the beach and full of ideas. This year I'm going to make a locally produced gearbox . I will make it to fit the BMW it will be a belt drive it will have a clutch but I'm breaking away from all previous design's and I'm going to try to get a fresh breath of air. The imported boxes are to pricey and the exchange rate to unpredictable. I have a fully equipped CNC workshop on my finger tips and there is no reason why we cannot produce a gearbox that will be at home on any good reliable engine . Toyota Honda BMW etc spring to mind the box plus the Eboxi's should be an good combination. With the waiting for CAA I have time on hand in the evenings.



Cheers Oupa-G

[AEROYOTA]

Hi There Oupa,

With the Yaris / Cobra project we started looking at this very same problem.
Look at this for a drive system:

http://www.morsetec.com/ets.html

Exact spacing, tension and alignment not so critical as with gears! Lubrication must me added though.
Perhaps lubrication bleed off from engine oil pump with flow back to engine sump.
Just a thought.

Cheers.

[Oupa-G]

AeroYota that is a very interesting link I want the simplicity of the belt drive, at the moment I'm still busy with the ideal ratio from a harmonics point of view if you look at the enclosed pictures harmonics and balancing is a very important topic.

Last year just before the festive season I had the counter weight of my engine come off and it produced metal salad in the bell housing , this was totally unexpected and I postponed the analyzing of the problem to in the new year. Last weekend I removed the engine and started searching for signs and symptoms. The counterweight definitely became undone first I could see the marks on the casing, but it looks like it was preceded by a problem in the flexplate . Luckily the balance shaft and the crankshaft passed the dial gauge test . Then late Sunday afternoon Boet popped in and cast his experienced eye and years of knowledge onto the problem and spotted that from one of the webs on the flexplate there was a crack and it was not new. So this put another angle to the problem. There must have been a fault in the flex plate or the imbalance caused by the 60_2 gear created an imbalance causing the early fatigue. I will definitely get some more opinions and as how to solve it . The final solution will be in making spigots and then to balance the whole lot and bring the rotating mass back to the original mass of the flywheel and what the engine was made for. This will take some time. Meanwhile the idea of making our own gearbox is going ahead and should not influence the present problem. I'm processing all the fotos and they will be added later today. Any knowledgeable comments will be appreciated.


Cheers Oupa-G

[pedro10012000]

I've been interested in following your progress with the BMW conversions. I expect you're well aware of the Polish guy and his PSRU's - but in case any readers are not, here's a link to his website, which includes some shots of the flywheel he produces as part of his BMW conversion kit.

http://aerotech-poland.com/index.php?go=8

[Oupa-G]

Pedro thanks I'm aware of his gearbox. The work is very nice. When we started the site I pledged to show all successes and problems. Only then we can advance and learn something. I have all ready been to my machine shop and will show the solution as soon as it is finished ,but it will have the same rotational mass as the engine as from the factory and all parts will be balanced.

Cheers Oupa-G

[Oupa-G]

It is early morning my head is working overtime . If there is a problem and you find out why, the problem disappears and Eureka last night this happened to me. It was troubling me very much that I had the unexpected breakage of the flex-plate, and how to prevent future happenings. I contacted my sources deep in the industry and the problem was unheard of. So it had to be what we added. First the 60_2 gear was the culprit , then the theory of rotating mass and balance etc. etc. However I was not happy so I took apart another engine I had and assembled the crank flywheel and the power take off from the gearbox and areas that were hidden I could now see. The bolts that hold down the centrifugal clutch on the crank adapter plate were to long and caused four pressure points on the case hardened flex-plate and bingo there is the freshly created stress point given some hours of load and the plate cracks like glass that has been nicked with a diamond cutter. The protrusion was so long that it actually deforms the flex-plate. It is a bit like having a six inch nail in a finely tune violin case.

The solution now is easy the CNC machines are being programmed and a new mass increased 60_2 will be machined balanced on the new balancing spigots and these parts will also be available to the people that imported gearboxes themselves because I was making to much money. However the gained knowledge is free and so far if I have yet to make any money on this project in matter of fact if this project was not financed by myself I would have gone "Bang" long ago with no further support or any further R&D. The rest of the engine is so superb that it would be a pity to stop now. We are aiming for Toyota Yaris reliability. The Saldanha boys are getting there Diesel Dog I think your work is so nice you can now come and visit me, you have them "pampiere"

Regarding the new box that will fit all , it is also keeping my brain spinning.

I sincerely hope that when I have the engine back in the Bosvark that the paperwork will be ready. Can you imagine if the engine is back in the Plane with no paperwork then what, I will have to revert back to vertical taxiing. All I can say my forced landing practices are up to date no scratch on the Bosvark. One little bit of advice do fly from landing spot to landing spot it is a nice game and gives you something to do when flying sometimes it makes you do a little detour or follow a road. Thats all for this early morning.


Cheers Oupa-G

[Boet]

Jaaaaa, dood moet n oorsaak he. You have found the smoking gun!! Found Oupa on Saturday afternoon, hands lekka dirty, looking at those parts, scratching and frowning. But if you look long and hard enough you will find what was wrong. Congrats old friend. I hope this is the last of the troubles!!

[Oupa-G]

Boet
Its got to stop sometime. I must say we did a lot of new things and hope to push the boundaries. Any result be it negative or positive is good , but no result is a disaster. Off to the meeting tonight. Hope everybody learns from this. Some time small things can have great effects.

Cheers Oupa-G

[Oupa-G]

In my search for the crack on the flywheel I dismantled another engine and to get a clean crankshaft for balancing purpose I had to take apart the connecting rods. On magnification I could not see the joint of the bearing cap. I continued and came upon a new type of machining a surface. It appears the factory does a controlled crack to create the bearing cap for the main casting , it is the first time I have seen this, I admit it I have not taken a modern engineered engine apart lately. I believe on inquiring that there are other engine makers that follow the same practice. I can see that it will give tremendous surface strength and stability in the cap assembly.

This is just an interesting aspect of the R1200 engine. No wonder the red-line is above 8000 rpm.

Enclosed some pics The making of the new parts are on schedule and I hope to be in the air soon.

Cheers Oupa-G

[pedro10012000]

Interesting technology!! To an innocent bystander it would look as if the con rod/bearing cap was ready for the scrap heap! I recalled reading about the cracking on a BMW statement re their K1200 engine - guess it's the same technique:

" Running in anti-friction bearings, the connecting rods are light forged components made of heat-treated steel. Measuring 120 millimetres or 4.72´´ in length, they interact with the short stroke of the engine to enhance the already high standard of running smoothness.

Together with the anti-friction bearings, the connecting rods weigh a mere 413 grams. Again taking up a typical BMW concept, the upper conrod opening comes complete with a bearing bush for a running life of more than 100,000 kilometres or 60,000 miles. The connecting rods themselves are split horizontally by proven crack technology breaking through the large conrod opening specifically on the middle level by means of a tensile force applied suddenly and instantaneously in a hydraulic process. The fracture surface provided in this way subsequently allows extremely accurate assembly without any further centring of the components."