Another "bird has hatched" in Port Elizabeth.
Promoting the airplane homebuilding industry in South Africa.
Contact Gavin Lawson if you are a homebuilder and require aircraft parts made or refurbished.
All photographs by Rego Burger. Read about his building a Cozy - Fish Eagle.
I am experimenting with a Q-tip on a prop. Many say the Q-tip does nothing but best test it myself. I am also adding carb cooling for the V8. In summer the hot air under the hood is too hot for the carbs, so a cool supply of air is a must.
One of the tips has been bonded into place. Carefull balancing and shaping to match the tips has to take place. The weight calculation of each winglet (Q-tip) must be the same.
The trimming and shaping still to be done.
This view of the outside top cowling, shows one of the 2 new air ducts for cooling is being made.
Inside of the cowling one can see the other duct and the directional scoops for the dashpots of the SU carbs.
Well folks since I'm doing another stint of 40 hrs flying to appease my SACAA I thought it prudent to test something new instead of just flying circles.
So I purchased a MGL Extreme EFIS see
image below, for less than the price of an old electric A/H.
The new engine management system display.
I took an instructor with and we where shooting a few missed approaches at a remote grass field (wont land there unless the wind is 40kts on the nose) away from international traffic when on go around no. 3 the engine start to shake rattle and roll and I was glad i did not have false teeth.
The young intructor looked at me perplexed thinking the engine was coming off. I told him to fly the aeroplane while I quickly looked to see if the EMS could help me figure what the earthquake was about. 2 crew is a great help in managing these things.
Walla the EGT on the right side was ice cold only the left was producing combustion.
I quickly explained to him the difference between SU carbs and std aircraft carbs.
New routine - check carb damping oil more often, at least every 20hrs. Added the oil and fired it up, all perfect again.
Thanks to the EGT system and EMS for helping me diagnose ASAP and a cool insrtuctor who kept calm. It is all knowldge and experience gathering.
Mods in June - July 2010.
Made another 2 improvements;
Right hand side, prop hub on the left.
Viewed from the centre of the shaft towards the engine.
The exhaust is my own design in rectangle tube to round conversion. Audibly it sounds like a symphony of pistons with the real V8 throb. No more crack through the propeller impact and no more soot on the propeller. The rectangle to round depressure chamber 1518cc each side seems to have lowered the noise a tad. I did not have my sound meter with me but the ear sense was much less stressful in the cockpit with head sets off and I could hear the radio speaker fitted in the back seat pretty well during run-up tests which was not easy before.
Making up the exhaust stacks.
Left hand side (from the rear looking forward) exhaust stack made. Just needs fitting.
Left hand side (from the rear looking forward) exhaust stack in place.
The right hand side done.
It is amazing what one discovers when you work out of the box, not all exhaust pipes need to be round, all of the time.
Why then the change?
Well firstly the exhuast port on the V8 is a rectangle 20 x 30mm, possibly the smallest exhaust port engine next to the mini engine. When I made the first pipe set, I had to beat the round pipe into a rectangle to fit, which I felt was a waste of time to please aesthetics. So I decided to stay with the existing shape. I made the interconnecting pipes as long as possible and all of the same length at 90mm into the expansion chamber. The expansion chamber allows the gasses to expand and cool in a split second. It then looks for an outlet which I have chosen to be 50mm round pipe, this is the part we see outside and should please most onlookers, but a 50mm square would have let out more are as the area of a square is larger than that of a round 50mm object thanks to pi.
I can't wait to test fly the extra 200rpm.
Test flying in May 2010.
Since the rebuild the nose has been
lengthened, colour added and wheel
In the original guise.
At 13500 ft looking inland from the coast.
Glide back joining cct at 2650ft to the field in to PE from 36km out and at 13500ft.
I never had signs of a fuel leak during the first test flight phase
A mistake, as the fuel disolved the foam and ran down
Fortunately pretty easy to fix without too much down time.
The aircraft's C of G being adjusted,
lead balance weights
At 16075 ft.
Time to climb from 6000 ft - 16000 ft was 18min. I could maintain over
The fuel consumption reduced hansomly to
22 l /hr indicating
Approaching the PE airport.
Back at the airfield. All in all another great weekend of test flying.