What is involved regulation wise adding an electric motor to a glider?

Not to hijack the thread, but in response to the reliability issue of two-stroke engines, the primary culprit seems to be the different altitudes at which the engine is supposed to start and operate. The fuel/oil/air mixture has to be within certain parameters for decent running and starting reliability. An increase in altitude (or high density altitude conditions) reduces the amount of available oxygen, which contributes to fouling the spark plugs. I used to ride the Yamaha RD-350 and TZ-250 motorcycles from Albuquerque (elevation ~5,500 ft. MSL) up to Sandia Crest (10,678 ft. MSL) and used to have to stop and adjust the needles in the carburetors four times on the way up and four times on the way down or risk plug fouling or overheating and possibly seizing the engine. About a 1,000 ft. change in altitude was all it took to affect the performance and reliability. Newer two-stroke engines with more sophisticated fuel injection systems seem to be much more reliable in motorgliders.

On Wednesday, February 3, 2021 at 5:10:11 PM UTC-6, Mark Mocho wrote:
Not to hijack the thread, but in response to the reliability issue of two-stroke engines, the primary culprit seems to be the different altitudes at which the engine is supposed to start and operate. The fuel/oil/air mixture has to be within certain parameters for decent running and starting reliability. An increase in altitude (or high density altitude conditions) reduces the amount of available oxygen, which contributes to fouling the spark plugs. I used to ride the Yamaha RD-350 and TZ-250 motorcycles from Albuquerque (elevation ~5,500 ft. MSL) up to Sandia Crest (10,678 ft. MSL) and used to have to stop and adjust the needles in the carburetors four times on the way up and four times on the way down or risk plug fouling or overheating and possibly seizing the engine. About a 1,000 ft. change in altitude was all it took to affect the performance and reliability. Newer two-stroke engines with more sophisticated fuel injection systems seem to be much more reliable in motorgliders.

Oh, that brings back memories. I too rode an RD-350 (voted as the "Bike most likely to lose you your driver's license"). Even tried production class road racing on it a couple times (scary). Had the same experience as you with riding in the mountains. Used to stop on the way up to Deal's Gap and drop the carb needles a notch. Put 38,000 miles on the bike. Never failed to start and run. Stopped being scooter trash and became glider trash, but still have that bike (mothballed since 1981).

Talk about hijacking...

I've had my Harley Davidson Wide Glide for almost 17 years and 137,000
miles and don't ride it too much any more though I did get it out a
couple of days ago when the temperature got up to 60 deg. Just
wondering what you did to mothball it. I've never done more than to put
on a battery charger now and then.

Dan
5J


On 2/3/21 9:36 PM, Wallace Berry wrote:
but still have that bike (mothballed since 1981).

On Wednesday, February 3, 2021 at 3:10:11 PM UTC-8, Mark Mocho wrote:
...I used to ride the Yamaha RD-350 and TZ-250 motorcycles...

I raced RD-250 in 250 Modified Production and TA-125 in GP classes during my mis-spent youth. Fun stuff, but there is no way I'd trust my life to the continued operation of a tightly-wound two-stroke motor. I didn't think I'd mess around with motorgliders at all until brushless motors and Lithium batteries came along. Now I think that electric motorgliders are poised to become the core of our sport, with pure sailplanes becoming more of a fringe activity.

On 2/5/21 6:31 PM, Bob Kuykendall wrote:
but there is no way I'd trust my life to the continued operation of a
tightly-wound two-stroke motor. I didn't think I'd mess around with
motorgliders at all until brushless motors and Lithium batteries came
along. Now I think that electric motorgliders are poised to become the
core of our sport, with pure sailplanes becoming more of a fringe activity.


if you're trusting your life to the operation of any motorglider engine,
you're screwing up bigtime. Electrics can and do fail, right along with
the others.

On Wednesday, February 3, 2021 at 5:31:51 PM UTC-5, David Scott wrote:
On Wednesday, February 3, 2021 at 11:35:51 AM UTC-8, Bob Kuykendall wrote:
On Tuesday, February 2, 2021 at 1:26:10 PM UTC-8, David Scott wrote:

Others have pointed out that this is easier for an Experimental glider. It is easiest for an experimental, amateur-built glider. For E-AB, depending on the operating limitations, you might have to notify the FAA and repeat Phase I testing. But nobody wants to see your engineering validation, and only the person signing off the annual condition inspection needs to review your workmanship. The FAA or DAR only wants to see that the paperwork is correct and that placards and operating limitations are correctly spelled out. A good DAR will look the airplane over to make sure it doesn't look particularly dangerous, but they aren't required to.

We have FES going into one of our glider kits right now, and are preparing for the installation of electric self-launch systems in future models.

--Bob K.
Since I am new here what kit do you produce? Are you preparing for FES or retractable pylon?
Any idea how much thrust an FES produces? My search came up empty.

Look up https://hpaircraftblog.wordpress.com
Lots of interesting info there- especially the old school stuff showing all the work it takes to get set up to produce a kit sailplane.
UH

On Wednesday, February 3, 2021 at 3:52:46 PM UTC-8, Hank Nixon wrote:
On Wednesday, February 3, 2021 at 5:31:51 PM UTC-5, David Scott wrote:
On Wednesday, February 3, 2021 at 11:35:51 AM UTC-8, Bob Kuykendall wrote:
On Tuesday, February 2, 2021 at 1:26:10 PM UTC-8, David Scott wrote:

Others have pointed out that this is easier for an Experimental glider. It is easiest for an experimental, amateur-built glider. For E-AB, depending on the operating limitations, you might have to notify the FAA and repeat Phase I testing. But nobody wants to see your engineering validation, and only the person signing off the annual condition inspection needs to review your workmanship. The FAA or DAR only wants to see that the paperwork is correct and that placards and operating limitations are correctly spelled out. A good DAR will look the airplane over to make sure it doesn't look particularly dangerous, but they aren't required to.

We have FES going into one of our glider kits right now, and are preparing for the installation of electric self-launch systems in future models..

--Bob K.
Since I am new here what kit do you produce? Are you preparing for FES or retractable pylon?
Any idea how much thrust an FES produces? My search came up empty.

Look up https://hpaircraftblog.wordpress.com
Lots of interesting info there- especially the old school stuff showing all the work it takes to get set up to produce a kit sailplane.
UH
I was wondering if that is what he was talking about. I followed that blog for a few years so am somewhat familiar with it.

I really would love to do this to my DG-800S with a fixed mounted 400N Swiwin or PBS ​Turbine. Fixed mounted for simplicity and less cost accepting the few points in loss performance. If I could do it for $20K, that would be cool. When you push the price to $40-$50K, then it's just better to buy a sailplane with a motor. Remaking the AW certificate seems daunting. Maybe if I found a DG800C with a bad motor I could do a engine swap from two stroke to turbine without a major modification affecting the AW. 17gallons per hour is still a lot of gas compared with the solo 2-stroke motors. I wish electric duct fan's were more efficient. The best 120mm commercial RC product only produces around 10kg of thrust on 150 amps. I can't wait for future tech to catch up to our propulsion needs considering the future loss of tow planes. Two stroke motors seem so problematic/finicky and antique considering all our modern inventions. The sound considerations comparing a turbine to a two stroke motor are not even close in the cool factor. Bring on the warp drive please that runs off my cell phone battery.
Walter Mitty
N800XX

On Wednesday, February 3, 2021 at 12:53:44 PM UTC-8, Ackerson Eyecare wrote:
I really would love to do this to my DG-800S with a fixed mounted 400N Swiwin or PBS ​Turbine. Fixed mounted for simplicity and less cost accepting the few points in loss performance. If I could do it for $20K, that would be cool. When you push the price to $40-$50K, then it's just better to buy a sailplane with a motor. Remaking the AW certificate seems daunting. Maybe if I found a DG800C with a bad motor I could do a engine swap from two stroke to turbine without a major modification affecting the AW. 17gallons per hour is still a lot of gas compared with the solo 2-stroke motors. I wish electric duct fan's were more efficient. The best 120mm commercial RC product only produces around 10kg of thrust on 150 amps. I can't wait for future tech to catch up to our propulsion needs considering the future loss of tow planes. Two stroke motors seem so problematic/finicky and antique considering all our modern inventions. The sound considerations comparing a turbine to a two stroke motor are not even close in the cool factor. Bring on the warp drive please that runs off my cell phone battery.
Walter Mitty
N800XX
I rode 2 stroke dirt bikes for years and found their reliability to be stellar so I don't understand why they are considered finicky or unreliable. Granted the idea of not having a throttle and running them at 1/2 throttle only is nuts. I did ONE cold seizure early on and that taught me to do a proper warmup.

"Condition Inspection" requires only an A&P.