Building the new Bushbaby SAFARI

[MYR]

(...) 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. (...)

Oupa-G, could you tell at which rpm begins the engagement of the propeller and at what rpm stops the slipping ?
Is it a dry or oiled clutch ?

[Oupa-G]

dear Myr The engagement is at approx 2000rpm it is a dry clutch it has a wonderful design with no moving parts . At 2000 rpm the prop only spins 625 rpm . So the prop hardly gives resistance so the transition is very quick with very little slip. It is a wonderful device and has the following advantages.
1 No load on the starter that also has to swing the enertia of the prop
2 100% safety when starting against prop strike on people (when an engine starts people move away)
3 One of those features like central locking on a car once you have tasted it you do not want to be without

Myr send me your email I have some diagram as you requested

Regards Oupa-G

[MYR]

(...) Myr send me your email I have some diagram as you requested

Done

I don't like very much reduced engines.
I prefer the only good direct drive motor for ultralites which is : UL260i of UL POWER but this 1170 BMW of TAKEOFF firm, improved by you seems very good.

[Cor]

Hi Frans & Kie,

Na gelang van gesprek tussen jou en Nico Visser oor die BMW enigine. Nico het eintlik namens my geskakel. Ek het so 'n BMW engine en wil graag op trike installeer. Stel belang in die koop van die kit wat julle verskaf om hom te laat werk soos hy moet. Sal ook graag wil weet wat die CAA roete is vir goedkeuring oor gebruik van die motor.

Cor & Alewyn Kritzinger (alewyn.kritz@gmail.com)

[Oupa-G]

Dear MYR

Life's a dream and there is never a perfect solution . Every engineering product is a multiple's of compromises. The UL260i is certainly a beautiful powerplant and installed well should give wonderful results. May I ask how many flying hours do you have, and behind how many different powerplants have you flown? Have you ever had the experience of engine failures? I have 6500hrs with several engine failures (broken valves , overheating seizures fuel problems etc.) The best engine failure is no engine failure!!!!!
If an engine stops there is always a risk of injury. With our project I'm putting 43 years of experience and a heap of caution into it. Our main object is reliability as was mentioned before in this section of the forum.

Kindest regards Oupa-G

[Boet]

I forgot to ad some pics last night. Was dog-tired, and 10 after I shut my computor down, I was in bed and a-for-away. Pics......

[Boet]

Today was a productive busy day. While the lads were doing the last bits of glueing on the wings, I finished silver doping all the tail feathers and a final coat on the fus. It now looks like a "blik" aerie. I then after a final ironing, the wings are now ready for the rib-stitching process to begin. But we ran out of time for today, so we have that piece of work cut out for us tomorrow.

[Oupa-G]

It looks so nice I just can't wait

Cheers Oupa-G

[AndyCAP]

Hi Oupa G. Sorry for the late reply - been a bit busy this week!

I used to be a member of TMFC just outside Durbanville and have very fond memories of a certain yellow Franklin powered Cub popping in for a visit with a little jack russel perched on the parcel shelf in the back. I was there the day when that Cub (pilot shall remain nameless! ) flew in formo with a 1/4 scale RC version flown by Johnny Calefato. In fact my godfather should still have some pics of that! I was very fortunate to get a flip in NAM from its current (?) owner from Petit about two years ago - was a cramped but awesome experience!

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.

Has the firewall (and pedals) actually moved forward relative to the seat backrest? I refer you to the attached pic of myself sitting in a BB Explorer. From what I can see on the pics I presume the design of the Safari's structure is indentical to that of the Explorer? Looking at the explorer. I really looked closely at the explorer trying to figure out if I could move the pedals forward and even possibly build a foorwell forward into the firewall . I think its possible but not ideal since it will mean that the whole pedal assembly would have to be mounted in front of the firewall tubular structure. Alternatively it could only move about 25mm forward. if the Safari has about 5cm or more legroom it will be VERY helpful for a langat like me!

Keep up the good work!

PS I see the advantages of the centrifugal clutch, however it does imply that its another item to check for wear. If it starts slipping, its as good as a partial engine failure. The other disadvantage is that you cannot propswing it -..errr.. well you can, but only the prop will spin like a windmill and the engine will remain deathly silent......

[AndyCAP]

Another three pics showing the squash!

Sorry for the slight highjack - as compensation you can use me as a test dummy for size comparison when the Bosvark is finished

PS NOTE these pics were taken of me sitting in an EXPLORER!

PPS I have posted these pics elsewhere before - so apologies for those who have seen them before

[Oupa-G]

Dear Andy Cap
Thanks for the reply the clutch is a very clever design with no moving parts and very trouble free , it engages at 2000 rpm and fully engaged at 2500 the real power absorbsion only starts at 4000 plus, so the clutch has very little slip or wear at all. A combination I would not like to swap for a solid connection. It is true that you are 100% dependant on a good battery and starter. I am looking into the possibility to make the clutch solid should there be a starter problem in some very remote area. Sofar we have had very little actually no problems with starters and on the bikes that is also no problem. Starters normally give some warning.
Keep well Oupa-G

[Cali]

AndyCap I feel your your pain . I am 6'5 and I have trouble fitting into most things. You have a couple inches over me in height, but I have a couple kilo's over you in weight to make up for it. Good luck. I was hoping someone would build a trike 1.3 times bigger than what they are now so I can fit more comfortably. Sure it is nice to have your ears kept warm by your knees, but it gets a little uncomfortable after a while.

[Dusty Eagle]

Hi Oupa G.

What you are doing is fascinating and may your success exceed your wildest expectations.

You should chat to the local bloke building the thunderbolt.

At what point does the centrifical clutch disengage.

With your power plant up front on a taildragger, aproaching very short finals and reduce the power, does the prop now windmill. What happens when you are just on the stall and need to bleed on the power to hold her there while you adjust for windage or to extend to miss the clump of grass and you need just that little bit of power to hold her off.
Will you have to give it a burst to 2000 revs to get a little thrust. How controllable is it down at low and off idle, is there any pull at all?.

regards,

Nico.

Ps. Boet, your quality is mouth watering.

[Boet]

Thanks Nico. today we finished rib stitching both wings. Another VERY cold day. I tried to glue the finishing tapes on, but the glue wants to blush. so had to quit. IF we have some heat and sunshine tomorrow I will finish the job.

[Oupa-G]

Dusty Eagle

When you fly the engine and you glide the prop windmills and when you need power the power band comes in at app 3500 the pickup is so fast that it feels like an ordinary engine that tricle of power that you need on short final is there when you need it . everything happens so smoothly and when you taxi in and stop and the engine idles the prop stops. It is awesome!!!!

Cheers Oupa-G