Testing Times

After a couple of years of flying solo, I decided that it was time to take passengers up with me.

Because the Shadow microlight has been completely re-built, RAANZ requires it be test flown at maximum all-up weight. 

Being a newbie to the Shadow, it was a bit nerve-wracking to do repeated stalls, steep turns and power descents. 

After each flight, I added another large steel weight (borrowed from the farm tractor) into the rear compartment.

Surprisingly, even at 6000rpm, the stall was pretty docile. The nose didn’t fall away. No sudden wing drop. Just that nose pointing ridiculously high in the sky, with the aircraft bobbling along at only 35 knots.  

Under-belly fuel tank

The original fuel tank on the Shadow microlight is only 23 litres. That’s very small when you’ve got a thirsty 2-stroke. I’ve done some one hour flights, but you can’t afford to ‘linger’ en-route.

Many Shadow and Streak owners fit an underbelly ‘slipper’ tank to gain extra flying time.

Working part-time in the Fi Innovations composites factory, I have access to some pretty cool technology. I decided to use vacuum-assisted resin infusion to build my slipper tank.

Derakane vinylester (like they make commercial petrol storage tanks from) is the preferred resin, because it does not get attacked by petrol.

After making and sealing an MDF and plywood mould, I carefully laid double-bias fibreglass fabric, stiffened with fuel-resistant foam core and layers of glass tissue inside. Resin inlet and outlet ports were fitted, then everything was sealed inside a see-thru plastic film, I applied a 99% vacuum for 30 minutes.

The magic happens when you open the inlet tap. It only takes a few minutes for the vinylester resin to completely saturate the reinforcements. Excess resin is automatically sucked out, so you end up with a lightweight, strong structure.

The tank’s top moulding was complicated. I designed it to fit around the undercarriage braces and wing strut tie-bar. 

The fuel sender is shrouded by its own cylindrical baffle, so that the fuel gauge reading is unaffected by any surge.

Six mounting points were added, each one strong enough to hold the fuel tank on its own. Probably over-built.

Lots of testing followed for leaks, unusable fuel and fuel feed. Fuel gauge was calibrated. Then it was off into the sky.

Now with 50 litres fuel, I can fly for 2.25 hours or more. Great.  If only my bladder would last  that long!

A Nose Job

The Shadow’s nose wheel got damaged recently during a landing.

I didn’t realise what had happened at the time.  All I knew was that the aircraft headed sharply to the right on landing.

It wasn’t until later that I saw the mangled nosewheel. The video taken by the onboard Sony action cam confirmed what had happened.

Looking at the video, you can see that the wheel was pointing to the right before landing. It did not like it having to instantly line up with the direction of travel. In addition, there was zero suspension movement because the bungee was way too tight. At touch down, the wheel just sledged sideways and everything bent. 

A real mess. The trailing arms got bent. The alloy spacers and AN5 bolts were bent as well. The tyre was severely rubbed, as I limped back to the hangar.

Anyway, a new noseleg was required, so I set about manufacturing one from 6061-T6 aluminium.

At the same time, I replaced the heavy rim and tyre with an original-spec unit saving 600g weight. 

I even added a mudflap to stop the sheep poo from splatting all over the underside of the fuselage!

Pourakino Peregrination

After winter, trying to fly in New Zealand can be frustrating. Strong westerly winds tend to dominate springtime. Fortunately, I did get a nice day to go flying in my restored CFM ‘Shadow B-D 582’ microlight aircraft.

I took off from Otautau, flew around Bald Hill in the Longwood Range, then down the Pourakino Valley to Colac Bay. Tracking east, I followed the rocky southern coast to Riverton. There I turned inland and returned to Otautau, via the winding Aparima River.

Butterfly or Moth?

Is a Shadow microlight, with its wings folded, a butterfly or a moth? 

You know. When buttterflies rest, they hold their wings vertically. On the other hand, moths spread their wings out wide. 

 

I guess that a Shadow is more of a butterfly, because its wings are vertical when at rest.

I built my own wing-fold system and fitted it to my restored Shadow B-D a few months ago. I like it, because I can easily rig and de-rig solo. The large-tyred castor wheels allow me to push the de-rigged aircraft across the loose gravel surface to/from the hangar.

Shadow Migration

Having finally found a hangar only 40mins drive from home, I flew my CFM ‘Shadow’ microlight from Manapouri down to a farm strip at Otautau.

After pre-flight checks and fuelling up at Fiordland Aero Club’s hangar, I took off and headed south-east. En-route flying conditions were very pleasant with a 10 knot easterly wind @ 2000 ft. Some low cloud in the valleys, but always a clear path towards Otautau. 

Since it was a lovely morning, I flew over Lake Manapouri, around the Monowai basin and wombled through the Twinlaw  hills, before descending to the farmland. At cruise speed, I covered 107km in an hour’s flight. 

The farm strip at Otautau is only 280m long, so first I did a low pass to check it out. Nearly calm at ground level. My landing was pretty average, but the Shadow pulled up with 100m to spare. I’ll need to practice accurate approaches.

Video, sound and GPS data was recorded on a Sony HDR-AS200V action camera.

This camera has WiFi, so I could remotely control the camera settings, and Start/Stop filming, with the live-view app on my iPhone.

The removeable Li-ion battery easily coped with more than an hour of Full HD video recording, with both the WiFi and GPS running.

A few days later, I edited the video using Garmin “VIRB Edit”. This free software allowed me to overlay the camera’s GPS track, speed, course, distance, etc onto the video clip.

Yah. I’m finally flying again!

Over Manapouri township

I travelled back up to Manapouri Airport to do some familiarisation in the Shadow microlight. Two days of near calm weather – perfect for me. Under Murray’s supervision, I did lots of taxying practice, and then some short hops just above the grass runway.

Then it was time to take-off. The Shadow climbed surprisingly steeply at 50kt, as I tried to keep it below the ‘flap’ speed. Landing is easier than I expected. 

I did 5 flights in just over 24 hours, so I was stoked.  After lots of circuits, I’m learning to control my speed on approach.

A new spring on the elevator trim tab, means that the Shadow will now climb ‘hands-free’ at 60kt airspeed and it can be trimmed to fly straight and level by itself. It still needs further fine-tuning, so it will hold a 50kt approach speed. 

At the end of the second day, Murray suggested that I go for a “tiki tour” of the district. I headed south-west past the little town of Manapouri, then followed the Waiau River down to the diversion weir. A left turn took me up the Mararoa River for a few km, then I headed back west. It wasn’t long before I was calling “Kilo Lima Hotel joining right base for Runway 32”. Very satisfying feeling to have re-built and now flown this aircraft.r

Into the Blue

Sunday started as a dreary rain day. I beavered away at Manapouri Airport doing yet another pitch change to the prop, as well as cleaning the brake shoes/drums and making a larger elevator trim tab for the Shadow B-D microlight aircraft. 

By mid-afternoon the rain had cleared. Murray Hagen declared that he would do some test flights. Having flown hundreds of hours in these machines, he was the best person to fly it for the first time since it’s restoration.

After a few long hops up and down the runway, Murray was off around the circuit. After this initial flight, we increased the prop pitch again.

Late in the day, Murray headed out for a final flight. The Shadow looked great in the air and got round the circuit pretty quickly. 

By this stage, Murray’s smile was very wide, “It’s a fun little aircraft to fly. I like it.” 

We ran out of time for me to do more than some taxi runs, so I’m itching to return to fly the Shadow soon. 

A long project with a successful conclusion. Thanks, Murray, for your help and encouragement.

Back story:

Murray and his friend built two CFM “Shadow” kits (ZK-KLH and ZK-TTE) in late 1988 in his farm woolshed at Pukemaori in southern New Zealand. Both microlights first flew in 1989 fitted with Rotax 532 water-cooled engines, the most powerful Rotax two-stroke engine at the time. 

Over the next few years, Murray flew ZK-KLH to lots of places in the South Island, until in 1995 it was damaged in a landing accident. Later he re-built the wings of crash-damaged ZK-MAX, so he is very familiar with the inner workings of the Shadow.

Fast taxi ride

Another weekend up at Manapouri Airport getting the Shadow B-D microlight aircraft ready for flight. 

This time, the weather was calm and fine.  It was ideal for Murray Hagen, the RAANZ test pilot, to carry out high speed taxi tests and short hops. 

Murray was pleased with the handling of the Shadow. He found that the right brake wasn’t working and the elevator trim tab needed adjustment, so I had some work to do overnight. 

He also wanted more pitch on the new Thompson wooden prop to reduce maximum static RPM. During the day, we kept tweaking the pitch, gradually increasing it to 19 degrees (@ 75% diameter). This process was made much easier by the nifty “Clinometer” app on my mobile phone.  

A significant change from last week, was to add a third radiator to keep the engine cool during the ground runs and taxi tests. The twin ‘tall’ radiators only work effectively when in flight, so with the 30 plus degree temperatures that Southland has been having, the Rotax 582 was having trouble keeping cool.

Gentlemen, start your engines

Last important job is to assemble and pitch the laminated wooden prop. This work of art was beautifully crafted by Brent Thompson. It uses the Precision Prop hardware, but he optimised its scimitar blade shape for the Shadow 582. 

At last, everything is bolted, screwed, glued or wired onto the Shadow microlight. Oil and fuel are in their respective tanks. 

Right, no more procrastinating. Just get on with the engine start. OK, roll the Shadow outside.  Malcolm and George appear like magic and offer encouragement.  Tie the aircraft to a couple of fence posts. 

Bit of mild panic, while the ignition key is searched for! Subconsciously delay a bit longer, by checking a few more bits and pieces. OK, let’s do it. 

After a few pulls, the Rotax 582 fires up easily. A huge relief after all the effort to get to this stage.

Over the next few minutes, we check things over.

  • tacho is reading 5000rpm at fast idle.*
  • handheld Icom A24 VHF radio works well
  • ancient Comtronics intercom has ‘packed a sad’
  • fuel and coolant temp gauges function
  • no response from EGT gauge ** 
  • plunger primer on the dash leaks fuel *^*

Then it’s switch off, push back and go home. It’s been a long hot 4 days.

*Next day my tacho reads only 1000rpm at idle, so it’s clearly a dodgy unit. We temporarily solve the problem by swapping it with the tacho from Murray’s 582 Thruster.

** Reversing polarity of EGT sender wires solves this issue.

*** Tossed out the plunger primer. Too scary to have fuel dripping out!