Building the new Bushbaby SAFARI

[Boet]

Thanks guys. Today started all sunny and bright, so we had time to finish putting on all the re-inforcing patches and strips on the fuselage. By about 9.30 it was completely cloudy, and VERY cold, so no chance of doping the fuselage today. We started preparing the wings for covering. I have to be in The Fairest tomorrow, but the lads will carry on regardless. I have given them more work than they can hande, so that will keep them VERY busy. (And out of mischief!) On Monday they will have to explain why everything is not finished. And NO, I am not a slave driver. Will look in on Oupa-G an Saterday sometime to see how he`s doing with HIS new spare parts. He left a complete Bee Em enjaain with me, to sort out the air-cooling part of it. We understand air cooling very well, so this one should be very straight forward. Trouble is, the "hot side" ie the exhaust side of the cylinder in facing backwards, so we have to configure it in such a way that most of the cold air is deflected not over, but AROUND the rear of the cylinder. Also, the baffling must be designed so that the patterns can be laser-cut easily, and supplied WITH each engine so that individuals does not have to battle the cooling issue all by themselves, but rather have a standardized kit available that works. I have huge expectations for this engine airframe combination. As they say: Watch this space!

[Oupa-G]

Dear Guest
The BMW engine has no place to fit a mechanical pump. If you take the redundency at present you must be logical because you still only have one crankshaft . Therefore I use the Prat and Whitney example . If something mechanical breaks you go down. For that reason you do a total overhaul like the P&W at 3500hrs so that it will run another 3500hrs and for that reason certain parts have a life time all to prevent unforcast stoppages With spark and fuel we opted for 100% total redundency. There are now on the market 100hp 110hp and 120hp BMW engines The torque is about 10nm lower then brand X but remember these motors spin like a turbine we limit them to 7000rpm the BMW redline is 8500rpm our Eboxi is set at 7200rpm it the cuts the fuel. The design lifetime on the electric pumps are 2000hrs plus Just think of your it has an electric fuel pump when last did you have one stop on you? In our case should you be so unlucky you switch to plan B it is installed.

Hope this answers your question

cheers Oupa-G

[MYR]

We understand air cooling very well, so this one should be very straight forward. Trouble is, the "hot side" ie the exhaust side of the cylinder in facing backwards, so we have to configure it in such a way that most of the cold air is deflected not over, but AROUND the rear of the cylinder.

I was wondering for a moment if you had thought this problem.
Is the oil cooling enough ?

Do you have the oil flow diagram of this engine ?

[Oupa-G]

dear Myr
We have all the diagrams and the oil flow channels diagram the problem is that you still apply old air cooled rules to a modern motor. So far we have collectively 330 hrs test flying under some very harsh Hot high conditions. Both the engines running have temp probes on the inlet and outlet of the oil radiator as well as the core temp of the engine . I have been measuring the valve play of the exhaust valves every 50 hrs with a micrometer to see any change. Any overheating will give valve stretch and ultimate failure. As soon as you put in hydraulic lifters you loose this diagnostic ability. To date we have had no overheating problems whatsoever. However if you enclose the engine in a cowling the internal airflow becomes very important this is true for all enclosed engines.

Regards Oupa-G

[Tailspin]

Oupa-G

What is the cost of the BMW engine

[Oupa-G]

Dear Tailspin

The price is directly influenced by the how much the owner gets his engine for but the rest that bolts on that is the gearbox and everything that bolts onto the engine excluding exhaust and oil cooler because that is instalation specific R45000. That means you can by a brand new GS1200 take out the engine sell the remaining parts fit the gearbox and you should have change from Brand X purchase price that just puts it all in perspective We encourage owners to source their own engines. I personally now buy any good engine that is worth putting in an aircraft. Luckily the bikers are a natural breed that have taken aviation at heart and like to live in symbiosis with their aviator friends.

Keep well Oupa-G

[AndyCAP]

Hi Boet & OupaG

This is awesome stuff!! Its so exciting to see the level of innovation that you guys are applying!I really think that the engine (and the plane) will be winners. From your description Oupa G, it is clear that you guys are not approaching this as a backyard job but rather like a true engineering development project. As an engineer myself I applaud you guys (even if I am just a tad jealous!! )

Boet I look forward to seeng a Safari - and trying it on . I looked at the spec comparisons posted on the suppiers site and was slightly dissappointed to see that the legroom seems to only have grown by 2 cm. so it seems as if you guys have kept the length of the nose and tail the same as the Explorer and BB? I presume this was driven from the perspective of using the same (or only slightly modified)jigs and tooling for the fuz sides?

I am sure that the wider cockpit will make it a lot more comfy for those larger individuals amongst us, but those few "lang gatte" like myself would really have loved to have an extra 10cm or so legroom. (ok I know at 6'7" I fall above the 99.5th percentile of the population - but a man can dream cant he?! )

Anyway keep up the good work - looking forward to following this story!!

[AndyCAP]

PS Oupa G het jy nie jare gelede ZS-NAM gevlieg nie?

[AndyCAP]

NS Oupa G, Het jy nie jare gelede ZS-NAM gevlieg nie?

[Oupa-G]

Andy Cap
Thanks for the compliments Yes we are taking this a step beyond serious as only enthusiastic amateurs can do. The tail in total is about 18 inches in die ou taal longer the lenght of the added baggage compartement is the tail longer . As I have extensive taildragger experience ZS-NAM, actually I was trained on Cub's in 1965 so the tailwheel is engrained on my brainstem. I fly all my aircraft as taildraggers. For me it was an adaptation when I used to fly the Citation to drop the nose so that she could go negative AoA before opening the reverse thrust buckets otherwise she would pop back into the air with catastrophic results. We are so serious about taildraggers that youre not even allowed to push a taildragger backwards then it has a wheel in front.

As you can see we have a springsteel gear. I had these made out of EN45 steel the same on your Toyota bakkie we cannot argue with that. It was designed that the aircraft has an AoA of 12% so a three pointer take-off is possible if terrain is difficult and you don't want to lift the tail. My springmaker is very complient . And the final touches of toe-in rake etc will be done on taxi trials . When gear is then ok it becomes the template for the making of more gears should people like it we will then also make a tricycle maingear for the less fortunate. There is more then the Eye on making a nice tailgear system. Take the tyre into consideration it must be round shouldered remember the old Tigers you can use outer third to run on as you load the undercaraidge the wheels scrub out making the gear less bouncy it is also a balance of mass scrubbing and softness of the steel that eventually will give the nice feel a taildragger should have. On full load the tyre runs center and on overloading or a hard landing she will run on the inner third of the tyre. On lateral forces the gear must be stiff enough so that the wheel will scrub and the wheel must not tuck. So tarmac and cement be careful but grass and gravel is OK We has already christened our plane the Bosvark so we hoping to give tarmac a miss where possible

On the choice of material I looked at AL FE TI Composite The composite for me was easy I know nothing about it and once set I can't make minor adjustments. The Al you need a 3X thicker spring then steel , steel is 3xstronger so no real weight advantedge. But with steel and induction heating I can do minor adjustments without changing the temper.

Jacobus Gertenbach wrote me a very nice engineering model and it was lovely to see how all the loading during the testing ran parallel to theory.

This is enough for tonight I will write on all the topics..

Andy you are 6"7 i'm 6"2 I'm sure you will fit you must remember the engine is coming forward which will give a lot of firewall space.

End of day Oupa-G

[Massimo]

Hi Oupa - G,

912s:
100hp/73.5kw @ 5800rpm
128nm @ 5100rpm
Installed weight of 64kg.

GS1200:
105HP/77KW @ 7500rpm
115nm @ 5750rpm
Installed weight 70.5kg

On paper it is seems that the 912s has more torque at much lower rpm and its approx 6kg lighter that the GS. Would this not make the GS less effective in terms of performance compared to the 912s?

Im sure you have taken this all into account before making your choice of motor. Perhaps you could elaborate on this and how you have compensated for this or your reasoning behind it all (not considering price and fuel efficiency).

Cheers
Massimo

[Oupa-G]

Dear Massimo

Yes I know all the figures The 912s is a magnificent it has a wonderful track record and can not be faulted . Just check the installed weight of a 912 does that include oil tank and the oil radiator and the water radiator. And all the pipes.

When we are finished I will weigh the installed engine with engine mount radiators exhaust etc. There is also a 912 Safari coming
only then will the actual performance be compared there is the final power at the prop. We will then see. The BMW was intended as a personal engineering project. It is a personal taste I do not like Bing or any other carburator. We have converted a 912S to fuel injection it is a different animal wonderful smooth and on a long trip the 912s and the 1200GS use the same fuel when they fly together. Give us some time all the answers are coming. Paper can say one thing the proof of the pudding is in the flying with the final result in five years time

Cheers Oupa-G

[Massimo]

More Oupa -G

Where are your daily soapie updates on the BMW? Kom nou, you cannot start a soapie and then keep us all with bated breath waiting in anticipation. This is like the Bold & the Beautiful of microlighters now. Can you imagine if B&B was not consistently shown, the ladies will have a riot. Now we dont want the same thing here do we.......please keep the soapie going.

[Arnulf]

More Oupa -G

Where are your daily soapie updates on the BMW? Kom nou, you cannot start a soapie and then keep us all with bated breath waiting in anticipation. This is like the Bold & the Beautiful of microlighters now. Can you imagine if B&B was not consistently shown, the ladies will have a riot. Now we dont want the same thing here do we.......please keep the soapie going.

Give the good man a chance to rest and recuperate.

[Boet]

OK, give Oupa a chance for some R&R. The lads did not let me down. Everything I gave them to complete, was completed when I walked in this morning. I`m impressed. Today the lads covered both wings, and I took to doping the fus. About two this afternoon it started raining, and it got VERY cold. Dope and cold, wet conditions do not mix, so I had to give it up. Finished two spinners on the lathe instead. Nice hot work. Saw Oupa G on saturday afternoon. Also had a look at Vliegvark`s Bee Em installation on his trike. Impressive. He took it for a flight around the patch, and the sound and performance on the engine is goosebump stuff. This engine is VERY smooth, it starts easy and warm-up is short. It is strange at first to see the engine start without the prop turning. The gearbox is not coupled directly on the engine, so the start and shutdown is not a noisy, clattering event. I presume also a lot easier on the prop and the gearbox as well. The centrifugal clutch also doubles as a " slipper clutch" in the event of a mishap. The more learn about this engine, the more I like it. Now just to get the aeries finished so we can mate the engines to the airframes. I can hardly wait, but I presume I am not the only one?