On Tuesday, August 31, 2021 at 7:16:53 PM UTC-4, Hank Nixon wrote:
On Monday, August 30, 2021 at 12:51:18 PM UTC-4, Eric Greenwell wrote:
On 8/30/2021 7:52 AM, kinsell wrote:
On 8/22/21 9:41 AM, jfitch wrote:
On Saturday, August 21, 2021 at 7:01:23 PM UTC-7, 2G wrote:
Yes, it does. According to LZ Designs there are 270 FES gliders flying right now. The
number of know fires is, at least, 3, and probably double that number. This puts the
odds of having a "fire" (really a thermal runaway) at 1 in 100 (minimum), or more
likely 1 in 50. This is about the same as the Space Shuttle.
Tom
I know of 3 fires in the AS Wankel powerplant in US gliders alone, with fewer numbers in
the fleet. Since you are flying that powerplant you are risking your life every flight.
In the Netherlands crash of the Pipistrel they in fact established that the batteries
"played no roll in the cause of the accident."
That's what they said. They also said a windmilling prop causes no drag if it isn't
generating electricity. Makes you wonder if the Dutch put their A team on the investigation.
That aircraft had major electrical problems, and was not airworthy by any reasonable
definition. It should have stayed parked far away from any structures, or other
aircraft. Similar to a Chevy Bolt.
If the electric motor isn't operating (unpowered), it will spin easily, and it will take
only a small amount of power to spin the propeller; hence, relatively low drag on the
order of a feathered propeller.
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation" https://sites.google.com/site/motorgliders/publications/download-the-guide-1
Not true in my experience. The windmilling prop on my 24EL reduces the glide angle from about 44 to about 20. Stopping the prop with the brake yields something in the middle.
UH
Having put just over 100hrs on this -24EL this season, I have some info.
Yes, part of my preflight is spin the prop by hand with the pylon fully up. There is a definite cogging of the motor when unpowered and prop spinning.
The decent rate with pylon up and prop windmilling vs. stopped is noticeably different. If the pylon is up, give me a stopped prop please! Unless I am under power, then a spinning prop is fine.
I have not done a self launch (although it can self launch) but I have done a few mid flight saves by gaining altitude as well as a "self retrieve" at a contest on a day where the weather tanked on the whole field.
Each time I used the motor I was ready to land (gear down, spoilers checked, field picked and at downwind entry point) and I did land with the pylon up a couple times but on an airport. Some of that was operator error.
If I'm landing with the pylon up, but not powered, I plan a pattern at about 1/2 dive brake rate.
Do I "count on it"?, no, but it's a nice option that I'm more comfortable with.
--- SoupGate-Win32 v1.05
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