$1 billion BMS Ooops...

On Tuesday, March 16, 2021 at 10:10:51 AM UTC+10, Eric Greenwell wrote:
2G wrote on 3/15/2021 3:31 PM:
On Saturday, March 13, 2021 at 7:59:59 PM UTC-8, Eric Greenwell wrote:
2G wrote on 3/13/2021 11:55 AM:
On Friday, March 12, 2021 at 7:27:24 PM UTC-8, Eric Greenwell wrote:
Dan Marotta wrote on 3/12/2021 10:30 AM:
Hows a self launch starting at 6,200' MSL up to 18,000' MSL followed by a distance of 350
nautical miles? That's what I'll be doing in June to relocate the Stemme from Moriarty, NM to
Rifle, CO. And it might use half a tank of gas.

Of course, I'll only do it that way if soaring conditions don't support gliding the whole way.

Dan
5J

On 3/11/21 6:18 PM, Eric Greenwell wrote:


How long a self-retrieve distance is the minimum acceptable to you?

Ok, you are not a current candidate for an electric motorglider (I knew that already :^) )

But, I'm still interested in Waremark's far smaller requirements. So far, the majority of the
pilots I've talked to that are considering moving to an electric self-launcher think 100 sm is
enough retrieve distance, and some think 50 miles is plenty. These are the people that are
willing to drive from where they live to where they want to fly. I'm one of those people,
because my wife and I like to travel in a motorhome with her sewing projects and sewing machine
in it.

Those must be flat-landers that don't have to clear even taller hills, let alone mountains. Your self-retrieve "distance" vanishes the moment you have to climb to clear an obstacle. Also, the electric self-launchers like the GP15 don't specify the retrieve distance when launching at MTOW. Think of it as getting you to a safe out-landing field which is how one pilot did at Ely last summer (and he took tows).
According to figures I have for the GP15, launching to 2600' agl at 8.5lb/ft2 uses about 20% of
the available energy (big battery); launching at 12 lb/ft2 would use about 28%. So, max
retrieve range would decrease comparably from 93 sm to 84 sm. Catch a thermal sooner, stop the
motor at 2000' agl, and it'd use 22%, so wold get 90 sm with the 12 lb/ft2 launch.

How often have you had to motor home more than 90 sm?
--
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

Just a few times, but I wasn't flying a 15M glider, either. In two seasons of flying the 31Mi I have only done one precautionary 5 mile "retrieve" only because I didn't want to do a marginal glide. Again, you ignore having to climb over obstacles. What would happen if you were 70 sm out AND had to climb 3,000 ft? And, then, throw in a 20 kt headwind. I probably wouldn't even consider flying the GP15 at Ely.
The answer to the situation you propose (not enough range to get home) is a simple one: land at
the airport that makes for the shortest retrieve before the battery runs out, wait for the
towplane (or trailer) to come, go home. At Ely, that would be 60+ miles, since airports are so
far apart; at Parowan, or home, as close as 20 miles.

The main difficulty would likely be the wind, not the 3000' climb, as using a climb/glide
flight for the return would already have climbs that exceeded that.

Anyway, relax a bit, don't let your range anxiety cloud your thinking. I have 4000+ hours in a
motorgliders, much of it in places with mountains - as you know. I assure you, I have used all
that experience when considering what glider is suitable for me. After all, I did write the
book on operating motorgliders :^)
--
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

Or recharge, then fly home the next day? I take a charger with me in my landout kit.

Most of the landout sites 60+ miles out of Ely, better bring a generator too....
On Monday, March 15, 2021 at 5:30:50 PM UTC-7, Matthew Scutter wrote:
On Tuesday, March 16, 2021 at 10:10:51 AM UTC+10, Eric Greenwell wrote:
2G wrote on 3/15/2021 3:31 PM:
On Saturday, March 13, 2021 at 7:59:59 PM UTC-8, Eric Greenwell wrote:
2G wrote on 3/13/2021 11:55 AM:
On Friday, March 12, 2021 at 7:27:24 PM UTC-8, Eric Greenwell wrote:
Dan Marotta wrote on 3/12/2021 10:30 AM:
Hows a self launch starting at 6,200' MSL up to 18,000' MSL followed by a distance of 350
nautical miles? That's what I'll be doing in June to relocate the Stemme from Moriarty, NM to
Rifle, CO. And it might use half a tank of gas.

Of course, I'll only do it that way if soaring conditions don't support gliding the whole way.

Dan
5J

On 3/11/21 6:18 PM, Eric Greenwell wrote:


How long a self-retrieve distance is the minimum acceptable to you?

Ok, you are not a current candidate for an electric motorglider (I knew that already :^) )

But, I'm still interested in Waremark's far smaller requirements. So far, the majority of the
pilots I've talked to that are considering moving to an electric self-launcher think 100 sm is
enough retrieve distance, and some think 50 miles is plenty. These are the people that are
willing to drive from where they live to where they want to fly. I'm one of those people,
because my wife and I like to travel in a motorhome with her sewing projects and sewing machine
in it.

Those must be flat-landers that don't have to clear even taller hills, let alone mountains. Your self-retrieve "distance" vanishes the moment you have to climb to clear an obstacle. Also, the electric self-launchers like the GP15 don't specify the retrieve distance when launching at MTOW. Think of it as getting you to a safe out-landing field which is how one pilot did at Ely last summer (and he took tows).
According to figures I have for the GP15, launching to 2600' agl at 8.5lb/ft2 uses about 20% of
the available energy (big battery); launching at 12 lb/ft2 would use about 28%. So, max
retrieve range would decrease comparably from 93 sm to 84 sm. Catch a thermal sooner, stop the
motor at 2000' agl, and it'd use 22%, so wold get 90 sm with the 12 lb/ft2 launch.

How often have you had to motor home more than 90 sm?
--
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

Just a few times, but I wasn't flying a 15M glider, either. In two seasons of flying the 31Mi I have only done one precautionary 5 mile "retrieve" only because I didn't want to do a marginal glide. Again, you ignore having to climb over obstacles. What would happen if you were 70 sm out AND had to climb 3,000 ft? And, then, throw in a 20 kt headwind. I probably wouldn't even consider flying the GP15 at Ely.
The answer to the situation you propose (not enough range to get home) is a simple one: land at
the airport that makes for the shortest retrieve before the battery runs out, wait for the
towplane (or trailer) to come, go home. At Ely, that would be 60+ miles, since airports are so
far apart; at Parowan, or home, as close as 20 miles.

The main difficulty would likely be the wind, not the 3000' climb, as using a climb/glide
flight for the return would already have climbs that exceeded that.

Anyway, relax a bit, don't let your range anxiety cloud your thinking. I have 4000+ hours in a
motorgliders, much of it in places with mountains - as you know. I assure you, I have used all
that experience when considering what glider is suitable for me. After all, I did write the
book on operating motorgliders :^)
--
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
Or recharge, then fly home the next day? I take a charger with me in my landout kit.

Matthew Scutter wrote on 3/15/2021 5:30 PM:
On Tuesday, March 16, 2021 at 10:10:51 AM UTC+10, Eric Greenwell wrote:
.....

Anyway, relax a bit, don't let your range anxiety cloud your thinking. I have 4000+ hours in a
motorgliders, much of it in places with mountains - as you know. I assure you, I have used all
that experience when considering what glider is suitable for me. After all, I did write the
book on operating motorgliders :^)
--

Or recharge, then fly home the next day? I take a charger with me in my landout kit.

I'm hoping that will be practical in the GP15. Overnight, even a small 500 watt charger would
be enough to add 50 self-retrieve miles to whatever charge was in the battery upon landing.
--
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

One issue not discussed is the duration / altitude of the launch. At Ely, and other sites (Williams is one), the launch may run well over 20 minutes and altitude gain over 3000 feet hunting for lift. The numbers supplied by the manufacturers are for a 1500' gain under 10 minutes. That difference will put a severe dent on the retrieve distances.
Craig

Craig Reinholt wrote on 3/16/2021 7:57 AM:
One issue not discussed is the duration / altitude of the launch. At Ely, and other sites (Williams is one), the launch may run well over 20 minutes and altitude gain over 3000 feet hunting for lift. The numbers supplied by the manufacturers are for a 1500' gain under 10 minutes. That difference will put a severe dent on the retrieve distances.
Craig

That hasn't been my experience at Ely, where a 2000' launch has almost always done the job, but
maybe I'm just lucky :^) Williams is a special case, and some FES will undoubtedly have to
take tows just to get to the soaring. It shouldn't be a problem for electrics with 50+ mile
range. Note that "the numbers" vary greatly between electric gliders, with some older FES
gliders having very limited climbs, and the newer mast-mounted motor systems by Schleicher,
Jonkers, and others offering 9,000'-13,000' climbs.

--
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 3/16/21 12:05 PM, Eric Greenwell wrote:
Craig Reinholt wrote on 3/16/2021 7:57 AM:
One issue not discussed is the duration / altitude of the launch. At
Ely, and other sites (Williams is one), the launch may run well over
20 minutes and altitude gain over 3000 feet hunting for lift. The
numbers supplied by the manufacturers are for a 1500' gain under 10
minutes. That difference will put a severe dent on the retrieve
distances.
Craig

That hasn't been my experience at Ely, where a 2000' launch has almost
always done the job, but maybe I'm just lucky :^)Â* Williams is a special
case, and some FES will undoubtedly have to take tows just to get to the
soaring. It shouldn't be a problem for electrics with 50+ mile range.
Note that "the numbers" vary greatly between electric gliders, with some
older FES gliders having very limited climbs, and the newer mast-mounted
motor systems by Schleicher, Jonkers, and others offering 9,000'-13,000'
climbs.


Well the Antares was supposed to have 10K feet climb capability, but in
reality it was a whole lot less. That shows the danger of comparing
real life performance of existing products with spec sheets of future
products. Don't suppose you went to Poland to verify the performance
numbers?

Don't suppose you went to Poland to verify the performance
numbers?

Are there actually any GP-15 gliders in the hands of private owners? Or are they still on some imaginary delivery schedule? The only one I know of that was in the US was sent back for "upgrades." Don't know if it actually flew before going "home."

Mark Mocho wrote on 3/16/2021 11:44 AM:
Don't suppose you went to Poland to verify the performance
numbers?

Are there actually any GP-15 gliders in the hands of private owners? Or are they still on some imaginary delivery schedule? The only one I know of that was in the US was sent back for "upgrades." Don't know if it actually flew before going "home."

No GP15 gliders are in the hands of owners. The February factory report indicated the first two
GP15s might ship in late March, but no March report so far. The one at the convention has been
sold, and is on it's way to Poland for updates that will bring it close to current production
specifications.

--
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 3/16/21 12:44 PM, Mark Mocho wrote:
Don't suppose you went to Poland to verify the performance
numbers?

Are there actually any GP-15 gliders in the hands of private owners? Or are they still on some imaginary delivery schedule? The only one I know of that was in the US was sent back for "upgrades." Don't know if it actually flew before going "home."


Both the one delivered to the U.S., and the factory demonstrator were
recently sold on W&W. Possibly the demonstrator will be in the hands of
a customer RSN. Has the small batteries from what I understand, and not
sure what they did with the wings. The one initially delivered to the
U.S. never got a flight in (without the help of a couple big turbofans).

kinsell wrote on 3/16/2021 11:39 AM:
On 3/16/21 12:05 PM, Eric Greenwell wrote:
Craig Reinholt wrote on 3/16/2021 7:57 AM:
One issue not discussed is the duration / altitude of the launch. At Ely, and other sites
(Williams is one), the launch may run well over 20 minutes and altitude gain over 3000 feet
hunting for lift. The numbers supplied by the manufacturers are for a 1500' gain under 10
minutes. That difference will put a severe dent on the retrieve distances.
Craig

That hasn't been my experience at Ely, where a 2000' launch has almost always done the job,
but maybe I'm just lucky :^)* Williams is a special case, and some FES will undoubtedly have
to take tows just to get to the soaring. It shouldn't be a problem for electrics with 50+
mile range. Note that "the numbers" vary greatly between electric gliders, with some older
FES gliders having very limited climbs, and the newer mast-mounted motor systems by
Schleicher, Jonkers, and others offering 9,000'-13,000' climbs.


Well the Antares was supposed to have 10K feet climb capability, but in reality it was a whole
lot less.* That shows the danger of* comparing real life performance of existing products with
spec sheets of future products.* Don't suppose you went to Poland to verify the performance
numbers?

A whole lot of experience and development has been gained since the Antares debut 18 years ago,
so I'm willing to accept the current claims by Schleicher, Schmepp-Hirth, and Jonkers. We don't
have flight reports for production GP15 gliders, but the power performance numbers on the spec
sheets are conservative when compared to other manufacturers' claims, so I am also willing to
accept GP's numbers as being close to reality.

I did not go to Poland, but dealer (Tom Holloran) did go to Poland and fly a GP15. Apparently,
he thought it was a very good glider, as he became the dealer, and one of the first few will be
his glider.

--
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