Finally, some good flying conditions. Up early. Dawn patrol. But lost an hour changing out the Polini starter motor. I heard that might happen. Good thing I had a spare. So, what’s the big news? The Merlin Lite has an excellent glide rate!!!!!!!!!!!!
Why is that big news? Because one can fly the Merlin Lite outside Part 103 parameters with just a glider rating and motor-glider logbook endorsement. and NO MEDICAL. That means you can add options like the 2nd fuel tank, nice paint, etc. A few pounds over Part 103 limits no longer matters. Apparently, it didn’t matter before but maybe some people care.
But we knew that the Merlin Lite qualified as a motor-glider before. I designed the wing to meet the FAA motor-glider definition. But still, this is big news because the aircraft really works well for a low-cost, multi-purpose motor-glider. I cut the throttle to idle at 3,000 feet AGL and a full 7 minutes later was still high on final! That works out to a very reasonable 328 FPM sink rate.
Further calculations you can verify on the video I am posting now. Gliding in at about 60 mph converts to 5280 feet per minute speed.
I cut the power at 3,000 feet AGL and glided to 700 feet AGL when I deployed full flaps for landing. 2,300 feet took 7 minutes! That is a LOT different than most, if not all, ultralights I know of.
Divide the 2,300-foot drop by the sink rate of 328 FPM = 16-1 glide ratio!!!!!!!!!!!!!
And that is with a 3-blade prop. The Polini has a clutch, so the prop simply freewheels. That is still drag but less than compressing an engine. I can easily use a 2-blade prop to improve performance a bit. Or perhaps a feathering prop if I can find one.
This confirms that the Merlin Lite is a viable motor-glider and at a fraction of the price of most other motor-gliders.
Furthermore, the electric-powered Merlin Lite, the Electrolite, will work very well with an endurance of at least an hour! In my cruise power tests I could fly at 58 MPH at only 4,800 RPM. I need 4,500 RPM just to taxi at 10 mph! Power requirements at cruise are exceptionally low. From today’s tests: 4,800=58 mph, 5,200=64 MPH, 5,600 RPM=67 MPH, 6,000 RPM=70 MPH, 6,300 RPM=73 MPH. The Merlin Lite trims ‘hands-off’ at all of these cruise settings!
And another takeaway: The engine does not care if the power is cut. Zero shock cooling. No load up. Ran perfect! This engine is liquid cooled and I install a thermostat. Full power climb to 3,000 feet and temperatures remained under 70C. Idle for an extended glide and temperature hovered around 50C.
I made a quick circuit to get a better idea of the take-off and landing distances. Unofficially, BOTH take-off and landing can be made in only 150 feet.
The Merlin Lite just keeps on getting better and better!
And here is the proof: https://youtu.be/LwqYkEQswcg