Best option for electric self starting glider

On 4/11/2020 12:46 AM, wrote:
airplanes, motorcycles, and boobs. It's a fun job, but somebody has to do it!
:-D

My fridge is open to you at Moriarty Municipal Airport, Dave!

Nice products and I liked your approach to adventure soaring.Â* We're
heading out on a different path, having an AirGyro AG-915
http://www.airgyro.com/ kit on order.Â* We should have been assembling
it or even test flying it right now but this damned virus thing has
things slowed down.

This aircraft will complete our toy box, sitting between the Stemme and
the Cessna 180K.Â* I do the maintenance on my 2004 Dyna Wide Glide in the
hangar, too.
--
Dan, 5J

There was a project in the UK for a UL Glider driven by a Motorised Main Wheel and a Jet. Website still up at http://www.proairsport.com/project-glow.php
However do no think it ever got of the Ground.

On Sat, 11 Apr 2020 08:10:55 -0700, Muttley wrote:

There was a project in the UK for a UL Glider driven by a Motorised Main
Wheel and a Jet. Website still up at
http://www.proairsport.com/project-glow.php However do no think it ever
got of the Ground.

I think it was taxiied and have a feeling that was without wings fitted.

But UL? Its empty weight, 180 kg, is the same as the Diana 2.

--
Martin | martin at
Gregorie | gregorie dot org

On Saturday, April 11, 2020 at 4:51:34 PM UTC+1, Martin Gregorie wrote:
On Sat, 11 Apr 2020 08:10:55 -0700, Muttley wrote:

There was a project in the UK for a UL Glider driven by a Motorised Main
Wheel and a Jet. Website still up at
http://www.proairsport.com/project-glow.php However do no think it ever
got of the Ground.

I think it was taxiied and have a feeling that was without wings fitted.

But UL? Its empty weight, 180 kg, is the same as the Diana 2.

--
Martin | martin at
Gregorie | gregorie dot org

I'd be interested to hear some reasons from the peanut armchair-aircraft-designer gallery as to why electric main wheels haven't "taken off" - seems like it would be a big win for both electric gliders in reduced launch energy, and solve the static thrust problem for jet self launchers?
The biggest problem I see is you'd need to have the main wheel a long way forwards, or a nose wheel to not pitch over on the belly?

On Saturday, April 11, 2020 at 9:04:39 AM UTC-7, wrote:
On Saturday, April 11, 2020 at 4:51:34 PM UTC+1, Martin Gregorie wrote:
On Sat, 11 Apr 2020 08:10:55 -0700, Muttley wrote:

There was a project in the UK for a UL Glider driven by a Motorised Main
Wheel and a Jet. Website still up at
http://www.proairsport.com/project-glow.php However do no think it ever
got of the Ground.

I think it was taxiied and have a feeling that was without wings fitted..

But UL? Its empty weight, 180 kg, is the same as the Diana 2.

--
Martin | martin at
Gregorie | gregorie dot org

I'd be interested to hear some reasons from the peanut armchair-aircraft-designer gallery as to why electric main wheels haven't "taken off" - seems like it would be a big win for both electric gliders in reduced launch energy, and solve the static thrust problem for jet self launchers?
The biggest problem I see is you'd need to have the main wheel a long way forwards, or a nose wheel to not pitch over on the belly?


Like to confirm a real world experience I had some years back while visiting El Tiro. I was there with my DG 800b took real interest in an Antares 20e that was tied down. I beleive the advertised climb from sea level in still air is 9000 ft. Well, sitting next to the glider was a hefty Honda gas generator. I asked the owner some question about his experience so far. First thing he said was he was disappointed. They found once the ground temperatures were above 100F they need to keep it in the shade before launch. If they left it ouside the batteries would over heat at around 1000AGL. Guess it� was designed for cooler climates like in Germany. Next I asked him how long it took to recharge the batteries from the generator.. He basically said all night long and consumed 10 gallons of gas. I doubt there are airports that would allow you to tap into their grid. El Tiro was using solar panels. On sites like Truckee where you can camp on the airport, you would become very unpopular in a hurry have that much noise. I have never seen an Antares fly from there, getting back into Truckee requires a climb to over 12,000 feet to safely get back in. The surrounding routes back in might have you starting the engine at 5-6k. Very marginal or impossible if you used the engine for self launch at the beginning of the day. In contrast the DG 800 will climb to well over 14k, personally in the winter I took off from sea level and climbed to 16k and it was still gaining 100-200 FPM. Recharging the gas tank takes less than 5 minutes for 5 gallons of fuel. When the battery's reach a much higher level of capacity and are able to be recharged in a different way, the electric glider will come of age, and i have no doubt they will. The backing to behind this push is driven by electric cars. Asking any one who owns a pure electric car and hear their stories on range anxiety. ONLY Tesla usiong super chargers do you see a charge time to drive time much less than one. My Volt is horrible! From a 110vac socket pulling 8 amps, it takes over 12 hours to get 40 minutes of driving time at 60 mph.

kinsell wrote on 4/10/2020 1:18 PM:
On 4/10/20 11:55 AM, Eric Greenwell wrote:
kinsell wrote on 4/9/2020 1:38 PM:
On 4/9/20 12:20 PM, Eric Greenwell wrote:
Magnus wrote on 4/8/2020 7:11 AM:

Where do you find the information about the LAK 17C? I can not find any, not
even on the LAK site.

My dream is for a smaller, lighter, simpler self-launcher, but with the same
performance as my ASH26E. I considered the miniLak, AS34, and the GP15. The
miniLak did not have enough wing loading, L/D, and powered range for the
Nevada/Utah area I often fly in, and the AS34 was just as big and heavy as the
ASH26E. So, I have ordered a GP15 for delivery next year, as it promises the
best compromise. It will be a few months, maybe longer, before we know if it
begins to fulfill it's promise.


Typing "lak 17c" into Google brings up multiple results, including an Oct 2018
test flight in FB.* Also been discussed on R.A.S.

I did that, and didn't find very much information. If it's not on the factory
site, it does not seem like a good choice to consider by a pilot that wants a
glider for next year's season. But, given it's an 18 m glider, it is unlikely to
meet my "smaller, lighter, easier) criteria.


It's on the Blanik America website with base price of 99.500 euros. Nice list of
accessories.* I saw a claim it was just a 17B-FES with a new wing profile, if
that's true then you would have the weight info.

http://home.nwi.net/~blanikam/ba/lak_prices.htm

Given GP's record in delivering gliders, I would take their promised delivery
dates with a huge grain of salt.

It would take major changes beyond a new wing profile to transform the 17B FES
into a self-launcher; regardless, I contacted the dealer in Nov 2019 about
electric self-launchers. He offered only the miniLAK (it ended up being my second
choice, after the GP15), and did not mention the 17C. It is odd that the dealer
lists the prices for the 17C, but no technical information.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

Luka Žnidarši� wrote on 4/11/2020 1:14 AM:
Note that at LAK17C max power is 30kW. With such power climb performance are very good as there is no pylon drag.

The pylon mount allows a much greater choice in propellers, allowing it to
significantly exceed an FES in efficiency. The GP15, for example, uses a three
blade propeller, and the blade shape is not constrained by the shape of the nose,
or the need for low drag when the motor is stopped. The pylon is a single,
streamlined strut that will produce almost insignificant drag at climb speeds,
even when accounting for the open doors. I base that claim on how well my ASH 26 E
thermals with the engine partially retracted for cooling, a much dirtier object
than the GP15 pylon.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

On Saturday, 11 April 2020 11:51:57 UTC-6, Eric Greenwell wrote:
Luka Žnidarši� wrote on 4/11/2020 1:14 AM:
Note that at LAK17C max power is 30kW. With such power climb performance are very good as there is no pylon drag.

The pylon mount allows a much greater choice in propellers, allowing it to
significantly exceed an FES in efficiency. The GP15, for example, uses a three
blade propeller, and the blade shape is not constrained by the shape of the nose,
or the need for low drag when the motor is stopped. The pylon is a single,
streamlined strut that will produce almost insignificant drag at climb speeds,
even when accounting for the open doors. I base that claim on how well my ASH 26 E
thermals with the engine partially retracted for cooling, a much dirtier object
than the GP15 pylon.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

While classified as a CLass 2 Hang Glider, this machine fits the objectives you defined https://www.youtube.com/watch?v=G3qfW3ydZuY&t=178s

Yes they are ridiculously expensive

In the Antares I'd expect to get to ~2500 feet AGL if the
ground temperature was 37C (100F). This at Sisteron at 1770
feet; so not a lot different to El Tiro altitude, this assumes that
the batteries/electronics are cool at the start. On my A/C the
climb limit would be the engine temperature not the battery
temperature. After such a climb I'd expect 50-60% battery
charge remaining so you'd certainly get a healthy climb at the
end of the day.
A Honda generator is a very non ideal way to charge the
batteries, perhaps it wasn't powerful enough? Plugged into the
mains (a 230 volt 16A supply) it rarely takes 7 hours to fully
charge.
As I've said before you cannot fly it like a DG800 but not many
pilots go from Antares20E to DG800.
And before the DG owners pass comment I did own a DG808C
for several years.
Dave Walsh

jld wrote on 4/10/2020 4:48 PM:
GP are getting their act together and increasing their manufacturing footprint.
We should finally see GP's coming out of the factory door.

Even if there is a little bit more complexity with a pylon mounted motor, there are clear advantages over the FES solution.
- more powerful motor
- better cooling
- better prop efficiency
- no prop strike risk
Another advantage of GP with large batteries is that, beside the larger energy capacity, the cells are discharged at lower amps rating and therefore run cooler.

The climb performance seems to be in line with flight test results.
As discussed before the published climb perf are without WB. Therefore TOM 320-330 kg. Even when flying empty, the typical WL will be ~42 kg/m2 which is already nice.
GP has made some good choices:
- light weight to allow very good electric climb performance (climb rate and altitude gain)
- high aspect ratio/low wing surface to achieve high L/D and higher WL. Maybe Max L/D will be a little bit less than 18m like ASH26 or DG800, but the L/D above 150 km/h should be better.

BTW, you need to add fixed ballast to get to 525 kg MTOM.

Regards,
JL

It's not clear going to a 525kg/7.78m2 = 67 kg/m2 (13.75 lb/ft2) wing loading is a
good idea, even in very strong conditions! That aside, the wing loading without
fixed ballast depends on the battery size, because the batteries take up space in
the wing that could be used for water. You can put in 130 L if you get the small
battery; but only 85 L using the big battery. I estimate I can go to 12 lb/ft2
with my weight (165 lb), the large battery, and 85 L of water. That should be
adequate, even in Nevada.

The minimum wing loading you can achieve depends mostly on the battery size you
select, as the large battery is 21 kg heavier than the small battery. That's a
2.7kg/m2 difference (about 0.6 lb/ft2).

Note that pilot weight is just the pilot - no parachute - as the glider has it's
own parachute.


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1