Over the past few weeks, I’ve been able to return to re-building my 1989 CFM Shadow ZK-KLH.
The next task was to make new canopy windows. Unfortunately, I couldn’t source tinted 1.5mm polycarbonate in New Zealand, so had to settle for clear windows. The old windows made good patterns, not only giving me the correct outline shape, but also allowing me to pre-drill the rivet holes.
Each rear window had a single central latch which resulted in bent lower tubes, so I opted to replace these with twin latches to securely hold the window closed. I machined new latch axles from solid alloy and filed two ‘flats’ to positively locate each inner lever (i.e. it no longer relies on friction to stop the inner lever from rotating out of alignment). Overall, these new latches are stronger and more secure, but only a few grams heavier.
The rear windows also have a full-length lower tube (with a matching horizontal cut-out in the rear bulkhead), so that the lower rear corner of the window is not floppy. Where each latch is drilled, there is an alloy sleeve to strengthen the tube and reduce the tendency for the axle hole to wear.
PS: You can see the small side windows that were added to the canopy shroud. They will give the rear passenger a better forward view.
The top and bottom cowlings of a Rans S6 microlight needed quite a bit of re-building after a prop blade parted company with the hub just on take-off. For a brief moment, the engine thrashed on its mountings and did lots of damage. The area behind the spinner was smashed and the cowling mounting holes where torn.
I carefully grafted in new carbon and repaired the cracks, taking care not to increase the laminate thickness. The cowling mounting holes were reinforced with alloy inserts. Since a different type of engine was being fitted a few changes were made to oil inspection flap, exhaust pipe cutaway, etc.
The Skyleader factory sent out a set of lightweight elevators for the GP One microlight. Made of carbon-fibre with a foam-cored skin, they are torsionally-stiff and have a very smooth surface. The 6 hinge pins were very challenging for me to fit because of the narrow aperture along the hinge line. But with some ingenuity with needle-nose pliers and plenty of patience on my part, they went together nicely.
The new elevators, and last year’s vertical tail unit upgrade, mean that the GP One can avoid any possible flutter up to 195 knots (360 kmph)!
To help reduce the coolant temperature of the Rotax 912 UL engine on the Skyleader GP One
light sport aircraft, I fitted a series of carbon-fibre louvres.to the cowling air intake. They proved to be very effective at scooping air and directing it through the side-mounted radiator, reducing the temperature by over 20 degrees C.
They work a treat and look great.
Back in June, two staff from the Skyleader factory traveled to NZ and updated SkyFreedom Aviation’s GP One to the latest specs. This included making significant changes to the exhaust, radiator and cowling layout.
As they left to fly back to the Czech Republic, they asked me to look after the assembly, engine run and initial flight. After completing some unfinished tasks and adding some extra features such as storage compartments, a friend and I transported the GP One to the Invercargill Airport where we assembled the light sport aircraft in the Southern Wings hangar.
On a miserably wet afternoon, I tied the GP One down and did an engine run. The temps and pressures came up OK.
I had to wait a couple of days for the weather to improve before flying the GP One.
More info at: Assemble aircraft and run engine
The Skyleader GP One which is SkyFreedom Aviation’s NZ demonstrator only had a single storage compartment, so that it was a challenge to pack and access all the items required for long cross-country trips. I have designed and manufactured a series of additional storage spaces to make the GP One more user-friendly.
First up was a lightweight carbon tray in the centre console. This is handy for mobile phone, pens, sunglasses, etc. The headset sockets are also recessed into this tray, so that the plugs are less likely to be bumped.
The second addition is a 50 litre luggage locker below the existing locker. It fits bulkier items such as jackets, daypack, lifejackets, etc. I used the hi-tech epoxy resin infusion process to manufacture it, which means that the new carbon/foam locker only weighs slightly more than the original fibreglass locker.
More info at: Luggage space
When the Skyleader factory staff returned to the Czech Republic in late June (after a very busy 10 day visit), there were a few unfinished tasks on SkyFreedom Aviation’s GP One demonstrator. Over the next few months, I worked steadily on completing these tasks.
Since the new exhaust has been re-located further aft, the under-slung radiator had to be shifted. It is now mounted vertically on the right side of the engine compartment, with ducting built into the lower cowling. It took some interesting welding and fabrication to align the radiator with the ducting and available mounting points.
More info and photos at: Exhaust and radiator changes
I helped a Rans S-6 owner to adjust the propeller pitch on his microlight. It was not going very fast in cruise mode, yet it would take off quite quickly. He figured something was not quite right.
He desperately wanted some more speed before he convoyed long distance to Rangiora with a Tecnam ‘Eaglet’ and my Skyleader ‘GP One’, both of which cruised easily at 100 knots.
We checked the blade pitch using a bubble protractor and found up to 1/2 degree difference between blades. Then we carefully adjusted it to have one degree more pitch. The result was pleasing – an increase of over 5 knots in cruise airspeed (now 85 knots at 5000rpm revs), but only a small decrease in take-off/climb performance.
Read about the trip http://www.skyfreedom.co.nz/news-blog/canterbury-foray
While doing a factory upgrade on the tail fin of the Skyleader GP One, one of the local U-Fly instructors asked me to repair a nasty crack in the nose cone of his Bantam microlight. A customer had sat down on it while waiting in the hangar, causing it to collapse under the abnormal load. A big crack had appeared in the fibreglass.
Since I already had all my glassing tools and supplies on hand, it was very quick to sand, mask and glass the crack. The owner was delighted to have a professional job done, instead of attacking it himself with a ‘surfboard repair kit’ from the local hardware store.