Building the new Bushbaby SAFARI

[Oupa-G]

This past week every evening was spent in the workshop except Wednesday when it was Club meeting. I was friendly reprimanded that the site was quiet but tonight I can prove why. The new exhaust with the removable tail pipe is letting my brain work overtime, having a quieter engine is always a bonus and when with the Black Box Viewer from the MGL instrument I can check any change in performance the test results can be scientific.

During the week I measured the reverse cone template on paper then transferred it to the perforated pipe and did the necessary cutting and Vliegvark did the welding. I'm showing the old tailpipe that made the airplane much quieter it took the bark out of the exhaust sound. The new cone will fit inside the tail pipe actually shortening it and it should reduce the tuning fork effect of a longer tailpipe. It will be test flown tomorrow wind permitting.

While I was playing with the little things Ystervark made and cut for me the new engine mount for my trike the 1100 motor is coming of and is being replaced with a 1200 with the full dual Eboxi systems. All the flywheel mods that were done on the 1200 are working well and when I fly the Bosvark and I put my hand on the panel I just feel no vibrations at all. So I'm also showing the new mounts.

Then as a good paparazzi I also have a first view of Ystervarks new trike it is stunning and the design is backed by a full stress analysis of every single part. It promises to be a very strong machine. More detail on the Trike's site. I see we are now on page 100 and some 174,000 hits. Doing the finer details is a lot of fun.


Cheers Oupa-G

[Oupa-G]

Did a RedX flight to George the weather was 100% clear but the QNH was 1005, in the Cape that is rainy weather but today was none. I fitted the exhaust insert and now the prop is making more noise then the engine.

Also inside the cabin it is much quieter so I'm happy with that result but today I was down 50 rpm on take-off but then the temps were 35C and the pressure was 1005 and it also had a high humidity. I will test all three exhaust tailpipes on the same day in succession and then I'll report the results and make it a bit more scientific. meanwhile the brakes on the Cruiser are giving of their warning sounds of brake-pad wear and that now becomes priority # 1.

Cheers Oupa-G

[Boet]

Ja-nee, ek sien daardie tailpipe het nou n belt, kruisbande en n strikdassie gekry! And the kleen green did the job!

[Oupa-G]

Dis nie altyd maklik om onder te kyk maar die manne met die kameras doen dit vir my

Cheers Oupa-G

[Oupa-G]

Over the weekend we tested the fuel flow of the other Safari #141 which is the sistership of Bosvark. The test we have done for this Safari is the in climb configuration fuel flow. On the BMW setup and there are other Bushbaby's which have header tanks, one should check for the worst scenario. The unassisted gravity flow should be 1.5 of the maximum fuel flow during take-off. Both the the BMW and the 912S use about 30 liters per hour under take-off power. So the fuel flow should be at least 45l/hour. In our scenario we drained the header tank and then opened the one wing tank and measured the flow. For the Safari we got 45 liters / hour.

As soon as the Facet fuel pump is switched on this increases to more then 90l/hour. This same test should then be done on the opposite side.

I operate my Safari from both tanks and have not experienced any lack of fuel or the header tank running dry. In my case the header tank breaths back to both tanks. I have not experienced any flow back to the tank if anything this breather will equalize the tank pressure. In flight the tanks are pressurized by the tank cap pressure tubes. If the two Facet pumps are activated and mine are switched together the last fuel in whatever tank , will always go into the header tank. So I treat my two tanks as one tank and on my MGL I only have one calculated fuel tank. As a further safety backup I'm busy with the making of a fuel low switch in the header tank that will give an aural as well as a visual warning. I hope never to hear or see this warning.

I have added some photies of the fuel probe experiment, Ystervark feels confident that he can manipulate these micro Farad figures. I'm also thinking of using a mercury float switch that will be simpler.

Fuel starvation or fuel problems are still the major cause for engines to stop so a good rethink can do no harm. Comments will be appreciated.



Cheers Oupa-G

[JOLO]

[quote="Oupa-G"] If the readers are interested I can give a summary of the building of the Vansin because I saw every part being built. It strictly is not part of the Bushbaby Safari build but I still think their may be some interest.


Please be so kind and do Oupa-G. I think it will make some interesting reading.
Awaiting episode 1!
Thanks
Johan

[Oupa-G]

I will do a series on the Vansin as soon as I have my trike in the air with the new 1200 engine this required a new mount as the the old mount has small dimensional differences.

The new mount was made in a jig welded and then stress relieved. THE MOUNT IS HEATED TILL IT LOOSES ITS MAGNETIC PROPERTIES . That is in the region of 650C or as the gentleman at the oven says "hy moet net pienk trek" Here is the example of a mount wat pienk getrek het. I will also post this picture on the Ystervark's Trike page so that his data is complete. Forgive the foto is out of focus for good hot reasons.


Cheers Oupa-G

[Oupa-G]

Have received some SMS's where I am and it is so quiet.

Well I escaped for a few days because I also need some rest sometimes. How ever my brain is in full speed thinking as I'm busy with the new engine mount for the BMW 1200 for my and Ystervark's trike. I have been pointed in the direction of a company in Wellington who are boffins on various poly Urethane products. The requirements of engine mount rubbers are different under parked conditions and in flight. Ystervark has made some molds for the Trike mounts and tonight I'm making some molds for the Bosvark. I'm having parts made of 70 Shore hardness and also of 60 Shore hardness, The part of the rubber that takes the static compression load should be 70 to prevent being compressed when standing idle in the hangar, but when the mount becomes dynamic it should act between 70 and 60 shore. This is the ideal lets see how close we can get to this dream. Just for information a car tyre is about 65 Shore.

Once the molds are finished I'll post the foties


Cheers Oupa-G

[KFA]

Hi Oupa, we use 55 and 60, just for comparison.

[Oupa-G]

K FA thanks for the response the molds I have made will interlock the two materials I am going to make them different colours and then it will be easier to understand I will play with the various hardnesses. my present mounts show signs of compression with my interlocking method I hope to prevent this. Time will be the final engineer.. I have to sleep now some foties of the finished molds.


Cheers Oupa-G

[Oupa-G]

I had lots of fun flying the Bosvark Sunday morning Boet arrived and I put him in the left seat of the OTT and the picture says the rest.

On Friday night I flew for RedX to George. The wind was southerly the dew point and temp split was not very far apart and the typical condition of drizzle rain where George gets its name Cold and Wet CAW.

Over the RT there was a 172 at night VFR from Bloem to PE alternate East London . I do not know how the pilot picked this flight, the epi centre of the coastal weather was just in that area, so he diverted to George which was already closing in. I was quite firm on the no go for George without an IMC rating and abilities. Oudsthoorn was the only place to go. Luckily the pilot landed I do not know with how much fuel and I was very relieved. This could have been a disaster. Oudsthoorn was not on his list of alternates. I ask myself why fly at night with a 172 with poor planning. There is either lack of training or the pilot involved lacks the insight. The mentor system would solve a lot of these problems. I hope I was a good mentor to the anonymous aviator.

On Sunday I took some pics and I must say the Bosvarkie is an absolute joy and all the little changes on airframe and engine and spring gear are working out well. The black box recording of the MGL instrument is wonderful I can make changes and then study the performance afterwards. At the moment I'm testing the exhaust and when Boet was flying a Tomahawk (TomaChicken) was also in the air over Grootfontein I could only hear the Tomahawk. That is the way I like it nice and quiet.

Enjoy the photies

Cheers Oupa-G

[Oupa-G]

I'm enjoying OTT she is due for some regular oil change filter change etc. The engine mount is in the way of the oil filter removal tool.

I prepared a socket with three spikes on them this is tapped in the filter housing and the filter comes of no problem.

Just a bit of useless information.

Cheers Oupa-G

[Oupa-G]

This afternoon it was pumping about 20kts down the runway after refueling I could not resist the temptation OTT is so responsive that gusty winds are no problem.

I have to check if the reflexes are still up to scratch.

Also did some work on my new engine for my Trike I'm replacing the 1100 with the 1200GS engine it will be nice to have commonality in parts filters etc. The engine I bought had some small damage to the front housing but I had that part so it was replaced. Off course Loctite was part of the assembly, and the torque wrench. Just some foties.


Cheers Oupa-G

[Oupa-G]

More then 180-000 hits. I have again been rapped over the knuckles for not writing and showing new things, however I have had complicated work with lots of thinking and long hours operating. Then I feel I'm not a youngster anymore. Then last week-end I flew Red X and was held in a hold because CT runway was blocked by an aircraft problem on the runway it was peak
hour and aircraft were in holds every where. The runway was soon clear an the controllers did a superb job and radar vectored us all in with separation and all. CT needs another runway but the higher thinking or non-thinking rather build shopping malls at the airport. I'm awaiting the day when there is a big boo-boo and a long haul low on fuel and the weather 'n " bietjie kak" and then their will be sports.

I had a lovely time with the mount rubbers the molds worked well and two sets of poli-urethane engine mounts were made.
Blue Shore 60 and black Shore 70. I'm showing how I fit a black ring around the blue center and then compress it to the length of the center sleeve. The length determines the amount of compression. The harder black part can withstand compression where the blue absorbs the vibration. I will fit these on the Bosvark and my new engine on the trike. I will report back.

Meanwhile ZU-OTT is flying well very smooth and all the temps are on the numbers. The flywheel mods are working well and she is the smoothest and I can not wish for better. Last weekend I flew for the first time the 120hp version of the 1200. Wow the power is amazing with the same prop that I get 6500rpm this engine went to 6900rpm. This weekend I will have to tune the EboXi to give more fuel. The donkeys are thirsty.

I'm building as many hrs as I can.

I have taken foties of the mounts enjoy them

Cheers Oupa-G

[Jean Crous]

Oupa-G i am impressed, but then again what else can one expect from someone with your experience , and interest in all things mechanical
Perhaps i could approach you for some rubbers for my Revmaster in my Bushbaby
Regards
Jean.