Building the new Bushbaby SAFARI

[Oupa-G]

Today I could open my fuel tanks by hand the leather seal works well with no binding of the fuel cap. It was a nice thick piece of leather and it was left in place for one week. There is something to be said for natural products. Today I did three flights on the second flight I flew straight and level maintained a zero on the VSI and opened the power 100% and the Airspeed climbed to 126 mph with a 6910 rpm so the prop is actually well matched. There was no vibration at all and the VNE of 140mph seems very realistic.
I'm finding the app speed to be very comfortable at 55mph and that speed correlates well with the GPS speed. The wind vector on the MGL Voyager is now very active so my static and the magnetic alignment is also accurate. Today we had a low ceiling so I could not do the low speed end of the flight envelope. We will see what the weekend brings.


Cheers Oupa-G

[Boet]

OK, nou wil ek he Oupa moet asb kyk wat cruise sy teem 6000opm.

[Oupa-G]

Boet 105 mph at 6000rpm.

Today connected the link to the injector and the fuel flow measured from the injector pulse. On my trike when fine tuned the accuracy is about 500ml on 80liters. On the MGL you create a virtual tank and then the amount of fuel used gets subtracted from the virtual tank. The amount of fuel that is in the virtual tank is measured with the dipstick and then entered as the value in the tank. This little plane is really coming into its own . I approach at 55mph over the threshold and on take-off she is solidly airborne at 43mph climbing away at 800 feet/m at 60mph. I've been landing at Wintervogel which is renowned for its graspolle and I also land on the grass at Morning Star, the gear just soaks up the rough areas. The landing is easy and if the app speed is correct at 1.3 of the stall once you have closed the power and you are six inches above the ground you take away the landing flaperon the tail becomes more heavy and the greaser follows. The BushBaby is definitely a delight to fly!!!!

Cheers Oupa-G

[Oupa-G]

Adjusted the K factor to 2700 and the fuel flows start looking right on the instrument. About 30 liters /hour for full throttle take off power that works out to 405 cc/kw/hour *0.7=283 grams of fuel /kw /hour leaned out in cruise we are aiming at 235 grams /kw/hour. Test flying I will see how close I get to the theory.

Cheers Oupa-G

[Ian]

WOW

What a fantastic thread, it should be mandatory reading for anyone considering building an aircraft

Especially pertinant to builders is the proving flight information / process etc.

I have learned plenty... and that's after I thought my proving flights were pretty comprehensive.....

Many thanks for sharing this detail Oupa-G !

Cheers ian

[Oupa-G]

Thanks Ian. I was with the University for 25 years and have found that one must share and exchange knowledge. It is only if you put your thoughts to paper you are actually pushing your own brain further.

Honesty in reporting is very important and also reporting the negative results.This thread has reported everything my broken propeller however was not shown in picture form that was to painful but it was reported. A person that only reports the positive and not the negative is also lying about other things .

I know a lot of aircraft are flying with for instance with the static source in the cabin or even better behind the panel. My findings are that that source varies so much that it renders the ASI useless as a reasonably precise instrument. I found the static pressure to be reasonably accurate in cruise but close to the stall the angle of attack of the fuselage is so high that it changes the static pressure to such an extent that what you see on the dial is only a number . Luckily for the cabin static port believers the number will always stay the same. So the approach speed will be 1.3 of a stable fictitious number. Luckily with the excellent MGL and the help of GPS we can quickly see the difference of indicated airspeed and ground. So the calibration of the static source is easier. On the Bosvark the static has been modified adjusted and I now have a reasonably accurate indication of the speed of the aircraft. For the aviators that live higher above sea-level remember the 2% rule . The rule is " the true airspeed increases 2%/1000ft density altitude. So for aviators that live at ground level 5000ft with very often a density alt of 7500ft the actual TAS is 15% more then the IAS. That is on take-off you have to go 15% faster on the ground then at sea level and that with less engine power. The 2% rule also works backwards on the engine power. Every time you take-off remember that The jets talk about Hot and High

Enough for this early morning


Cheers Oupa-G

[Oupa-G]

This afternoon went for my medical for the ATP and was declared fit Class I medical for the next 6 months also got a class IV medical so that I can fly the small planes. Next week for the Skills test.
This weekend I will train my co-ordination skills as aviator in the Bosvark.

Cheers Oupa-G

[Oupa-G]

Today was a perfect day for flying. The virtual tank was programmed the Kfactor judged and some final fine tuning on the Eboxi. The fuel was measured in the tank with the dipstick and the figure entered into the Voyager and then I flew it for 1 hour. I started with 73 litres and landed with 59 litres . That is 14liters/hour. In this hour I was playing around with full throttle and pushed her to 132mph so I'm still 8 mph short of the VNE. no vibrations no instabilities or anything abnormal. This flight was uneventful and the Bosvark is getting closer to the point where I feel that there is not much more to do but to do a lot of flying. I must say that the magnificent MGL Voyager is helping a lot to make the testing so much easier. The temp are really very stable and they are all in the deep green.

The highest temp is of the exhaust valve cooling oil entering the oil cooler at 100 degrees C the sump temp is then 85C.
The day ended and I took my SD card and down loaded the flight folio. This technology will make that I have to revisit the flight folio concept. It will need some rethinking, we are living in 2010 not in 1930. Carrying a printout of the last page should be efficient. The MGL does not forget to record the data. Thats all for tonight.



Cheers Oupa-G

[Boet]

And now for Oupa`s attention, the 3rd Beeemdawweljoe enjaain is in. Seems like the silencer will somehow not be bothered by the nosewheel suspension bracket. So far WAB seems to be OK.

[Oupa-G]

Boet thanks for the photies the standard Bosvark exhaust will work that is I will now make a jig from Bosvark II 's exhaust and will then make-up the Korck exhaust. Interesting that the nose gear does not interfere at all. I have bought an EGT indicator from MGL , it will be fitted to my 1200 GS bike and I will test run and see what EGT temps the factory run their engines. I know they run the engines very lean from an emission point of view. Will post the results.


Cheers Oupa-G

[Boet]

The baffeling has been completed on this BB today, and now we are busy with the cowling. My "quality controller came" by to see what I was busy burning the late-night candle for. (Rib-stitching the gatveertjies of MY aerie!) She grew up with my kids, and almost feels like she is part of my family. Verry purdy!!

[Oupa-G]

The test program is running well. Sometimes it is interrupted by a flat tyre but that happens in the best of families. I was flying the tyres reasonably soft .75 bar I can tell you that it is not enough because I pinched the tyre and one moment she is sweet and the next moment it is full rudder and full opposite brakes. But all ended well and the wheel was soon fixed the tyre pressure is now 1.5 bar in the mains and 3 bar in the tailwind. The virtual tank was filled with 85 litres and I used it down to 45 litres on the virtual tank and the dipstick agreed. I have been using this system for the last 6years on my trike and it works extremely well so there is no reason why it cannot work on the Bosvark. The fine tuning of the Eboxi is also getting more refined and I'm now monitoring the bike on which I installed the MGL EGT. It is however very difficult to let the bike engine work as hard as the aeroplane engine. If you do a cruising speed power settings the bike does 160k's and on an Easter weekend that is not so clever. The EGT's run higher on the bike then I have ever seen on the Bosvark. I post some pictures.


Cheers Oupa-G

[Oupa-G]

The Easter weekend was busy I started of by fixing a guy that worked with a grinder , unprotected face and the grinder blade went through his face. For all us working with machines let us please rethink safety and protection. I also had a visit from Derek of Whisper fame, he brought me his Arplast prop and I set it on the Bosvark and copied the Bosvark map to the Whisper Eboxi. I'm very interested in the results. On their airfield they have a Whisper that had a 4 cyl Jabiru engine which was replaced with a 6 cyl Jabbi. Then there is also a visiting Whisper with a 912S. I believe the BMW Whisper has the shortest take-off run of the three, the BM definitely has the vooma. This weekend gave me time to continue test fly the Bosvark at various power settings. She is running so well that I now do 1 hour runs at various power settings fine tuning the MGL wonder instrument and getting fuel consumption figures. 6000rpm 105 mph 17L/hr, 5500rpm 90mph 13L/hr that is also the best torque curve setting. The EGT's run at 730C so I think I can still lean this out a bit , I however first want to see the road test on the bike. If I cannot find a suitable road then the Dyno will be the answer. So I will burn a little more fuel for the time. All the flying as been done with the South Easter Wind pumping between 20 and 30 mph. The control on the Bosvark is so excellent and predictable that these winds and this turbulence it creates is no problem at all. I have now done 30hrs and the test flying is coming to an end. The next 10 hrs will be dedicated to performance figures and writing the Manual. I have enjoyed this project so much doing all the mating of the various components. If we get long levity out of this powerplant and time will tell this is definitely an engine to consider in the future.
This coming week I'm going to do the climb test as that is part of the figures I have to submit to CAA. I will take foto's of the MGL screen because that is the easiest way to record the data.


Cheers Oupa-G

[Oupa-G]

The deeper I get into the flight testing the happier I get. The fuel system is working very satisfactory . I can side-slip to my hearts content, I could do with a bit more rudder authority, this is only notice-able during slipping on landing there is plenty of rudder authority. The flaperons give a slightly different feel then the normal ailerons. When the flaperon deflects down the centre of lift moves aft and on the upward flaperon the lift moves forward. Maybe I'm just critically observing it however is no problem it is just different. I find this little plane such a joy to fly and the control authority over the weekend in the high wind conditions we had was absolutely superb . On one of the longer flights it was quite bumpy and I was thirsty I had some cooldrinks with me , it was absolutely possible to fly her with rudder only leaving me with two hands free. Trimmed out with the flaperon lever she holds her altitude just naturally. During this manoeuvre I saw the speed slightly increasing and it seems she wants to fly with a touch of flaperon. I'll still get the hang of fine tuning this docile bird. The fuel management is also coming to age the fuel flow and the virtual tank fed with the information of the dipstick the reading of the dipstick is then entered as the virtual tanks capacity which feeds into the header tank. The fuel flow is then quantified by the brilliant fuel computer of the MGL and the signal comes from the injector and the resultant calculated fuel is subtracted from the virtual tank. The system has been working well on the trike the last 6 years so I'm going to stick to it. As a matter of fact the PC12 works the same way. Because of this I redesigned the engine information section so now I have only one tank. When I reach 20L I will switch on the fuel pumps to make sure all the fuel reaches the header tank and I feel that at 10L the plane must be on the ground. The 10L plus the 5L in the header tank should give a safe margin. I'm looking forward to this weekend's test flying . In the photo's I showing the newly designed screen and the integral part of the fuel management the ever so important dipstick. The newly designed screen will be loaded onto the Voyager tomorrow.


Cheers Oupa-G

[Rudix]

Hi Oupa-G

Interesting observation on the move of the center of lift when you change the flaperon position, it is exactly the same I am experiencing with the flaperons on the Savannah!

Thanks for all your hard work keeping us informed, I never miss an "episode". I am seriously considering powering my next plane (Zodiac 601HD) with a BMW.....

Fly safe,
Rudi