Building the new Bushbaby SAFARI

[Spool-Up]

Oupa-G and Team Bushbaby

"Better is the enemy of good"... An interesting saying indeed!

Thanks for those thoughts. I have actually looked at a great number of kits, including the Sportsman... A really nice design.

My decision to go with the Safari has been based on a few simple factors. Those being a local factory, simple, proven construction method, looks, size, and portability/packability. Until the introduction of the Safari (& Kitfox SS), I considered the aircraft too small. That has fortunately changed, and I believe the Safari will be a very good, efficient, interesting, and capable light aircraft.

My idea with the wings/aileron system may complicate matters a bit, but I plan to get the design work done before beginning with the construction. I also have a 1941 Stearman, for which a mod exists, to give it an extra set of ailerons on the upper wing. This wing design of the two aircraft are remarkably similar, and I'll use this as the basis for my drawings. The aileron actuation system can be easily copied (and refined) from the system used on the J3 Cub (simple & reliable).

Not too big a change if well planned, carefully executed, and properly tested. Then again... I have done quite a bit of work on "lap & draad", but I've never built a kit from the start. Maybe I am being a bit naive regarding the effort required.

I'm also watching your BMW GS1200 firewall-forward work with much interest. This looks very, very good! May well change my "conventional engine" mindset if yours works well.

I don't want to hijack this thread with my fantasies though! Watching your build with much interest! I can see that I'll need to ask for plenty of advise when the time comes. I hope you won't mind.

Best regards,

Rich

[ystervark7]

Stephan

This is a follow-up on yesterdays reply regarding the map. We have done some tuning today at the lower revs (we are still inside so we can go to about 3000RPM) and learned some new lessons.

From previous experience we know that we should tune the idling to be as lean as possible, if you do not you foul up the plugs on the BMW to such an extend that it does not want to run at all. This normally mean that you must replace the plugs at R200 ea at BMW! (You should be able to resurrect them again if you run them up to temperature.)

We were able to tune the idling EGT's to run at about 700 degC @ about 1000- 1200RPM which we think should stop fouling up. In the process we found out that we might need another RPM bin or two so I am going to increase the number of RPM binds to 10. That mens we will have an 8x10 map.

Note that on our existing BMW engine with about 150 hours we only use a 1x10 lookup. We can do that because we are using a fixed pitch propeller.

[Stephan van Tonder]

Yes sorry Yestervark meant interpolation. On the system I use they allow you to have a non-linear map for exactly that reason - at idle and away from idle to around say 4000 rpm you can have the RPM steps closer to each other and then increase the step on the higher rpm where it is not so sensitive. Of course that is to allow smooth acceleration and fine throttle control at low rpm in cars and probably not 'that' important on an aero engine setup. You can even run non-linear on the TPS as well to give better control at small throttle openings - again probably not a big thing for aero setup.
Of course there you also have the option of running closed loop wide band lambda - is that something you guys might even consider?.
Just for some ideas you can have a look at the site and in the middle there is a button where you can download their demo software - gives you good idea what they get up to in the car business. These boys have grown form a system very similar in size to what you are using now - 8x8 sites and some basic injection and spark to some very advanced systems in the last 8 years. http://www.perfectpower.com/products/standalone.asp

[Oupa-G]

Dear Rich everything is possible. We picked the Bushbaby for the exact same reasons and further refinements are always welcome. Good luck and happy building the last 10% is the difficult part. To Stephan I think Ystervark has got the Lambda sensor up his sleeve ,but at this stage we want to run slightly rich because there have been some piston holes reported on the bikes with a specific software. At this stage we venture on the safe side. Once the cooling baffling has been sorted out the next step is run leaner there is a facility to control the mixture by hand. I know the newer Lambda sensors are less vulnerable to lead but no lambda sensor no problem with Avgas. At some airfields only Avgas may be available, we do not know for how long though. Cable tied all the sensors and busy making inspection doors for pre-filter inspection and oil level checks. Everything eats time , the night is calling.

Cheers Oupa-G

[Oupa-G]

I see we have passed the 33000 hits mark what a wonderful response thank you all, we are trying to keep up the standards and keep it interesting.


Cheers Oupa-G

[Stephan van Tonder]

Yeah lambda (especially wide band lambda) sensors don't like lead but I doubt they will die from a single tank full. What is nice about tuning closed loop on the Perfectpower is that you give it the lambda taget you want to hit and then give it a range that it is allowed to deviate from your base map to try and hit that target. - SO if you want to run it rich you simply make it's lambda target a little rich and it will hit that at all times - no matter what your altitude above sea level is. It has lambda target values for each throttle position and deviation values the same cells as in your main map so the same size grid so you can also have varying lambda values per throttle position. That means you can run it pretty lean on idle and then have it richer as you open the throttle and quite nice and rich on full throttle.

[conradza]

I've been reading your progress with interest and thought of maybe doing something similar. I was just wondering about the availability of used BMW engines in South Africa. I'm working in Germany till the end of September and I had a look around here and found quite a few at between 2000 and 3000 Euros.
If the engines are not easily available in South Africa I suppose it would make sense to buy one while I'm in Germany.

I would also like to know which model BMW engine will be the best to buy.
Any advice will be appreciated.

Conrad

[Oupa-G]

Conrad we are using the GS 1200 we are also using the RT1200 and the 1200S. The GS 1200 we have already running for 120hrs. The second hand prices in SA are about 3000 Euro depending on condition . They are there but not plentiful.

Cheers Oupa-G

[Boet]

Bosvark no 2 has all it`s baffle plates in. I simplified the bottom baffle for the sump. This was the first engine baffled with the kit supplied by Oupa. Bit of minor trimming required here and there, but on the average much easier to do than starting from scratch. Belief ne, I know, I made the original set from which the kit is copied. It takes a lot of patience and a lot of ally plate! I am now very much copying what Oupa does, and helping along the way so by the time he is ready to fly, no 2 should not be far behind!!

[Boet]

Sorry, here are the pics.....and a pic of my BB, still sans powerplant

[Oupa-G]

I see we have passed the 34000 mark what a wonderful response. Been busy all weekend, made time consuming radio and transponder brackets , installed the final panel also installed the aerials. Then to come the final linking of the altitude encoder of the Voyager and the transponder.All the little things eat up a lot of time. I'm aiming at finishing everything in the home workshop and then take it finished to the airport. The mating of the wings we have already done. So I expect no snags there. The week is starting again tomorrow. So I will have to go and sleep. Just some pics.


Cheers Oupa-G

[KFA]

Hoe lank nog Oom Frams??? The suspence is killing us

[Oupa-G]

I'm working flat-out lot of little things do not want to move it out of workshop because otherwise I have to drive to the airport.

but it now is not very far off.


Cheers Oupa-G

[Oupa-G]

Things are nearing completion have Friday afternoon earmarked to do all the paperwork and the dual inspection of all controls. Boet is coming on friday and then we will inspire each other with the paper war he is more experienced then myself. Things are now exciting.

Cheers Oupa-G

[Ou Man]

Had a quick peek at the Bossot this morning. Man, all those wires ……! Frans/Jan, your baby looks beautiful, (even without wings). Looking forward to see this major achievement realize in a perfect “take off”