$1 billion BMS Ooops...

On Sunday, 7 March 2021 at 22:04:16 UTC, Moshe Braner wrote:
On 3/7/2021 8:31 AM, Martin Gregorie wrote:
On Sun, 07 Mar 2021 04:44:36 -0800, Mark Mocho wrote:

It suggests one way to make mass electric-powered air transport work:
Put the pax and cargo in nice accommodation on a large airship and tow
it cross country behind an electric locomotive running on repurposed
AmTrak tracks.

And just what happens when the train goes under a bridge?

Another unicorn inspired idea. Keep 'em coming. I need the laughs.

The author is a bit more than a unicorn, methinks. He's well-regarded in
technical circles.

Anyhow, if such a system was set up it could obviously only work on lines
that have no tunnels and that don't run in deep valleys (so not on the
Glendale-Denver line obviously), and that have been 'adjusted' so that
the line is always at the top of the crossing stack.

It would also be faster than the old Goon Show concept of horse-drawn
zeppelins.

Or you can use the newfangled idea of making that airship very narrow
and fly it very low to the ground so it can go under the bridges and
through tunnels. Oh wait...

While the rest of the world has double-tracked and electrified their
long-range railroads (e.g., the trans-Siberia), here in the US we sit on
our heels while a few loonies play with "pods" and other nonsense.

But I'm getting further off topic. Gliders are nice. They don't need
no steenkin' engines.

I have yet to see a glider take off (bungee launches excepted) or return from a field without an engine.

Enjoying this thread. I'm a newbie - flying XC for about a year now. I definitely would like self-launch capability and just some 'modest' sustaining capacity left over. My land outs and close calls to-date could have all been mitigated by 10min (or less) of sustaining assist. If I fly so deep into marginal conditions that I need an hour of power to get home, I must have really made some bad decisions. Soaring conditions here in southern AZ are pretty great but land out options can be challenging. I see sustaining needs as more about dealing with localized exceptions and improving your land out choices. If I needed 1 launch or 10-15min flight time, I don't think the conditions were aligned for the XC flight I was looking for anyway.

Example: I was recently surprised by continuous 7-9kt sink over a 15mi final glide. I started out with a 3200' agl arrival altitude cushion and watched it drop to 200ft as I soldiered home and left my last favorable LO options behind. I was stuck looking at an emergency bailout on a mine tailing that has generated a number of scary tales in my club. I was lucky to find some lift off a local feature just 2mi out and got enough altitude to make the field in good shape. 2-3min of powered sustaining flight would have made that a non-event.

One launch and some modest assist capacity would be awesome and fit my primary goals:
- independent launch capability
- backup for the times I need a short boost to avoid a land out or help get me to a safer land out option
- I'm ok with landing out on occasion if its safe and retrievable
- Really prefer electric over ICE

Seems like the current mast-mounted electric technology is just about there for my goals. It's now more about solution maturity, track record, and $$ as I watch how things shake out. I do, however, want hear about alternate use models and scenarios that could affect my decisions.

JJ

If you are thinking of a motorglider as saving you from an unsafe landout, you are a Statistic - In -Waiting. What a motorglider does is save you the inconvenience of a safe landout and retrieve. If anything, it makes landouts more dangerous, as the pilot workload at a critical point increases (and this is an argument for electric, which typically takes less attention). A motorglider does not increase your range over unlandable terrain, or improve your chances for a safe landout (not reliably, anyway). Your example of continuous 7 - 9 knot sink for example, would be turned into continuous 5 - 7 knot sink with a typical sustainer, and it would take the most powerful of self launch power plants to turn that into a climb (even if you are lucky enough to have the motor start). A motor is no substitute for intelligent decisions, and it is not a substitute for having an easy glide angle to a safe landing site at all times. I have two friends with motorgliders left in trees that can bear witness.

Regarding who might replace an ICE with electric: I might be a candidate, if my engine were to fail in a way that required replacement. The $30K replacement cost and 6 months waiting time certainly would allow some contemplation. The glider already has doors, a prop, a boom, a jack to deploy the boom, capacity to carry around 150 lbs in a spacious engine bay. All that is left are the hard bits: motor, motor drive, and battery.

On Tuesday, March 9, 2021 at 10:36:11 AM UTC-8, John Johnson wrote:
Enjoying this thread. I'm a newbie - flying XC for about a year now. I definitely would like self-launch capability and just some 'modest' sustaining capacity left over. My land outs and close calls to-date could have all been mitigated by 10min (or less) of sustaining assist. If I fly so deep into marginal conditions that I need an hour of power to get home, I must have really made some bad decisions. Soaring conditions here in southern AZ are pretty great but land out options can be challenging. I see sustaining needs as more about dealing with localized exceptions and improving your land out choices. If I needed 1 launch or 10-15min flight time, I don't think the conditions were aligned for the XC flight I was looking for anyway.

Example: I was recently surprised by continuous 7-9kt sink over a 15mi final glide. I started out with a 3200' agl arrival altitude cushion and watched it drop to 200ft as I soldiered home and left my last favorable LO options behind. I was stuck looking at an emergency bailout on a mine tailing that has generated a number of scary tales in my club. I was lucky to find some lift off a local feature just 2mi out and got enough altitude to make the field in good shape. 2-3min of powered sustaining flight would have made that a non-event.

One launch and some modest assist capacity would be awesome and fit my primary goals:
- independent launch capability
- backup for the times I need a short boost to avoid a land out or help get me to a safer land out option
- I'm ok with landing out on occasion if its safe and retrievable
- Really prefer electric over ICE

Seems like the current mast-mounted electric technology is just about there for my goals. It's now more about solution maturity, track record, and $$ as I watch how things shake out. I do, however, want hear about alternate use models and scenarios that could affect my decisions.

JJ

On Tuesday, March 9, 2021 at 1:55:27 PM UTC-7, jfitch wrote:
If you are thinking of a motorglider as saving you from an unsafe landout, you are a Statistic - In -Waiting. What a motorglider does is save you the inconvenience of a safe landout and retrieve. If anything, it makes landouts more dangerous, as the pilot workload at a critical point increases (and this is an argument for electric, which typically takes less attention). A motorglider does not increase your range over unlandable terrain, or improve your chances for a safe landout (not reliably, anyway). Your example of continuous 7 - 9 knot sink for example, would be turned into continuous 5 - 7 knot sink with a typical sustainer, and it would take the most powerful of self launch power plants to turn that into a climb (even if you are lucky enough to have the motor start). A motor is no substitute for intelligent decisions, and it is not a substitute for having an easy glide angle to a safe landing site at all times. I have two friends with motorgliders left in trees that can bear witness.

Agree with all your points and I don't think I've ever seen a motor related thread that doesn't preach the obvious: don't rely on your motor to keep you safe.
I'd also mention out there's a large difference between 'safe' LO sites. Some offer convenient accommodation (wide-open approach, smooth surface, room for a long roll-out, aerotow retrievable, drive the trailer onto the field, beer nearby, etc). Others are more challenging but ultimately safe for the pilot. Challenging LO's include short fields, glider scuffing through low vegetation, bouncing across uneven surfaces, losing a gear door in a freshly plowed field, unexpected livestock, locked gates, no trailer access, needing you and your crew to attend a mine safety class before being allowed to retrieve your glider, etc.
I don't think these types of LO variations are particularly unique to AZ. It's part of our XC decision making process and risk assessment. It's important to always have a safe-for-the-pilot LO option. I make sure I do. Just like I did in the example I provided. But there are many defined safe LZ's in our area that you would definitely prefer not to land in. I'm very well acquainted with the distinctions and tomorrow, I'll be out on my 4th all-day land out survey expedition to document this season's current LZ conditions for a segment of our club's usual XC operating area. Having 100's of hang gliding XC 'land outs' with no prior LZ familiarization just doesn't cut it now that I'm flying gliders XC.
I did a bit of math using my recent example's igc log. I assumed that I turned a motor on at 5mi out (10mi into that final glide - the point which I clearly knew the highly undesirable mine tailing land out was a distinct possibility). With average sink rate changing from 8kts to 6kts - I make the field just below pattern altitude. While that's nice to see, it's a whole lot closer that I would have assumed and your point regarding limited glide improvement is a good one - thanks.

JJ

One thing a motorglider allows you to do is to select safer landout sites - not because you can motor away from a bad one, but because retreating towards a safer area, while still high, has less risk of inconvenience. A fair number of landouts in bad places can be attributed to wanting to get closer to home to have the retrieve be shorter, passing up better - but further away - choices. We had two landouts in a lake last year which probably had this as a component in the decision making. With the possibility of a motor start, retreating towards a nice safe paved runway does not have the same consequences for the rest of the evening.

When you are thinking about that final glide in sink, remember that pulling the motor out to start it will cost you a few hundred feet in altitude, even if it fails and you are able to put it away again. If it fails and you are unable to put it away, you've just given up about 1/2 your glider performance. On my glider the difference is 50:1 going to 20:1. The jets are a bit better and an FES better still, but there is still consequence, even if it is just a distraction from efficient flying. This is a real dilemma on a marginal final glide in a motorglider. I don't have a comfortable glide. Should I pull the motor out now while I still have enough altitude to try to deal with the consequences? If it doesn't start I will for sure not make it.. Should I have pulled it out 5 minutes ago? Too late now - will I regret, 5 minutes from now, not having pulled it out now? All these things run through your head.

On Tuesday, March 9, 2021 at 3:53:52 PM UTC-8, John Johnson wrote:
On Tuesday, March 9, 2021 at 1:55:27 PM UTC-7, jfitch wrote:
If you are thinking of a motorglider as saving you from an unsafe landout, you are a Statistic - In -Waiting. What a motorglider does is save you the inconvenience of a safe landout and retrieve. If anything, it makes landouts more dangerous, as the pilot workload at a critical point increases (and this is an argument for electric, which typically takes less attention).. A motorglider does not increase your range over unlandable terrain, or improve your chances for a safe landout (not reliably, anyway). Your example of continuous 7 - 9 knot sink for example, would be turned into continuous 5 - 7 knot sink with a typical sustainer, and it would take the most powerful of self launch power plants to turn that into a climb (even if you are lucky enough to have the motor start). A motor is no substitute for intelligent decisions, and it is not a substitute for having an easy glide angle to a safe landing site at all times. I have two friends with motorgliders left in trees that can bear witness.

Agree with all your points and I don't think I've ever seen a motor related thread that doesn't preach the obvious: don't rely on your motor to keep you safe.
I'd also mention out there's a large difference between 'safe' LO sites. Some offer convenient accommodation (wide-open approach, smooth surface, room for a long roll-out, aerotow retrievable, drive the trailer onto the field, beer nearby, etc). Others are more challenging but ultimately safe for the pilot. Challenging LO's include short fields, glider scuffing through low vegetation, bouncing across uneven surfaces, losing a gear door in a freshly plowed field, unexpected livestock, locked gates, no trailer access, needing you and your crew to attend a mine safety class before being allowed to retrieve your glider, etc.
I don't think these types of LO variations are particularly unique to AZ. It's part of our XC decision making process and risk assessment. It's important to always have a safe-for-the-pilot LO option. I make sure I do. Just like I did in the example I provided. But there are many defined safe LZ's in our area that you would definitely prefer not to land in. I'm very well acquainted with the distinctions and tomorrow, I'll be out on my 4th all-day land out survey expedition to document this season's current LZ conditions for a segment of our club's usual XC operating area. Having 100's of hang gliding XC 'land outs' with no prior LZ familiarization just doesn't cut it now that I'm flying gliders XC.
I did a bit of math using my recent example's igc log. I assumed that I turned a motor on at 5mi out (10mi into that final glide - the point which I clearly knew the highly undesirable mine tailing land out was a distinct possibility). With average sink rate changing from 8kts to 6kts - I make the field just below pattern altitude. While that's nice to see, it's a whole lot closer that I would have assumed and your point regarding limited glide improvement is a good one - thanks.

JJ

On Tuesday, March 9, 2021 at 7:01:56 PM UTC-7, jfitch wrote:
This is a real dilemma on a marginal final glide in a motorglider. I don't have a comfortable glide. Should I pull the motor out now while I still have enough altitude to try to deal with the consequences? If it doesn't start I will for sure not make it. Should I have pulled it out 5 minutes ago? Too late now - will I regret, 5 minutes from now, not having pulled it out now? All these things run through your head.

Good points. I can see where a 'backup' motor sounds great on the surface, but in practice its whole 'nother set of complex decisions and uncertain risk tradeoffs. More so than I was considering.
Continuing to benefit from this thread - thanks.
JJ

On Wednesday, 10 March 2021 at 02:01:56 UTC, jfitch wrote:
One thing a motorglider allows you to do is to select safer landout sites - not because you can motor away from a bad one, but because retreating towards a safer area, while still high, has less risk of inconvenience. A fair number of landouts in bad places can be attributed to wanting to get closer to home to have the retrieve be shorter, passing up better - but further away - choices. We had two landouts in a lake last year which probably had this as a component in the decision making. With the possibility of a motor start, retreating towards a nice safe paved runway does not have the same consequences for the rest of the evening.

When you are thinking about that final glide in sink, remember that pulling the motor out to start it will cost you a few hundred feet in altitude, even if it fails and you are able to put it away again. If it fails and you are unable to put it away, you've just given up about 1/2 your glider performance. On my glider the difference is 50:1 going to 20:1. The jets are a bit better and an FES better still, but there is still consequence, even if it is just a distraction from efficient flying. This is a real dilemma on a marginal final glide in a motorglider. I don't have a comfortable glide. Should I pull the motor out now while I still have enough altitude to try to deal with the consequences? If it doesn't start I will for sure not make it. Should I have pulled it out 5 minutes ago? Too late now - will I regret, 5 minutes from now, not having pulled it out now? All these things run through your head.
On Tuesday, March 9, 2021 at 3:53:52 PM UTC-8, John Johnson wrote:
On Tuesday, March 9, 2021 at 1:55:27 PM UTC-7, jfitch wrote:
If you are thinking of a motorglider as saving you from an unsafe landout, you are a Statistic - In -Waiting. What a motorglider does is save you the inconvenience of a safe landout and retrieve. If anything, it makes landouts more dangerous, as the pilot workload at a critical point increases (and this is an argument for electric, which typically takes less attention). A motorglider does not increase your range over unlandable terrain, or improve your chances for a safe landout (not reliably, anyway). Your example of continuous 7 - 9 knot sink for example, would be turned into continuous 5 - 7 knot sink with a typical sustainer, and it would take the most powerful of self launch power plants to turn that into a climb (even if you are lucky enough to have the motor start). A motor is no substitute for intelligent decisions, and it is not a substitute for having an easy glide angle to a safe landing site at all times. I have two friends with motorgliders left in trees that can bear witness.

Agree with all your points and I don't think I've ever seen a motor related thread that doesn't preach the obvious: don't rely on your motor to keep you safe.
I'd also mention out there's a large difference between 'safe' LO sites.. Some offer convenient accommodation (wide-open approach, smooth surface, room for a long roll-out, aerotow retrievable, drive the trailer onto the field, beer nearby, etc). Others are more challenging but ultimately safe for the pilot. Challenging LO's include short fields, glider scuffing through low vegetation, bouncing across uneven surfaces, losing a gear door in a freshly plowed field, unexpected livestock, locked gates, no trailer access, needing you and your crew to attend a mine safety class before being allowed to retrieve your glider, etc.
I don't think these types of LO variations are particularly unique to AZ. It's part of our XC decision making process and risk assessment. It's important to always have a safe-for-the-pilot LO option. I make sure I do. Just like I did in the example I provided. But there are many defined safe LZ's in our area that you would definitely prefer not to land in. I'm very well acquainted with the distinctions and tomorrow, I'll be out on my 4th all-day land out survey expedition to document this season's current LZ conditions for a segment of our club's usual XC operating area. Having 100's of hang gliding XC 'land outs' with no prior LZ familiarization just doesn't cut it now that I'm flying gliders XC.
I did a bit of math using my recent example's igc log. I assumed that I turned a motor on at 5mi out (10mi into that final glide - the point which I clearly knew the highly undesirable mine tailing land out was a distinct possibility). With average sink rate changing from 8kts to 6kts - I make the field just below pattern altitude. While that's nice to see, it's a whole lot closer that I would have assumed and your point regarding limited glide improvement is a good one - thanks.

JJ

A marginal final glide in a motor glider (FES perhaps excepted) is a final glide in a glider in my mind.

What actions did you take to get out of the sustained sink? Having owned and flown pure gliders, sustainers, and motor gliders I can attest that an engine is not a substitute for xc skills. If you want a
sustainer, imagine flying the flights you have flown with half a load of water that you cannot dump. Every time the engine starts should be a surprise, because
if it doesn't start you now have effectively full open and locked airbrakes.. I fly an engined glider just like the engine is not going to start. Twice I have landed out without even attempting the engine as I have a hard deck
where below I will not be stupid.
Jon



On Tuesday, March 9, 2021 at 10:36:11 AM UTC-8, John Johnson wrote:
Enjoying this thread. I'm a newbie - flying XC for about a year now. I definitely would like self-launch capability and just some 'modest' sustaining capacity left over. My land outs and close calls to-date could have all been mitigated by 10min (or less) of sustaining assist. If I fly so deep into marginal conditions that I need an hour of power to get home, I must have really made some bad decisions. Soaring conditions here in southern AZ are pretty great but land out options can be challenging. I see sustaining needs as more about dealing with localized exceptions and improving your land out choices. If I needed 1 launch or 10-15min flight time, I don't think the conditions were aligned for the XC flight I was looking for anyway.

Example: I was recently surprised by continuous 7-9kt sink over a 15mi final glide. I started out with a 3200' agl arrival altitude cushion and watched it drop to 200ft as I soldiered home and left my last favorable LO options behind. I was stuck looking at an emergency bailout on a mine tailing that has generated a number of scary tales in my club. I was lucky to find some lift off a local feature just 2mi out and got enough altitude to make the field in good shape. 2-3min of powered sustaining flight would have made that a non-event.

One launch and some modest assist capacity would be awesome and fit my primary goals:
- independent launch capability
- backup for the times I need a short boost to avoid a land out or help get me to a safer land out option
- I'm ok with landing out on occasion if its safe and retrievable
- Really prefer electric over ICE

Seems like the current mast-mounted electric technology is just about there for my goals. It's now more about solution maturity, track record, and $$ as I watch how things shake out. I do, however, want hear about alternate use models and scenarios that could affect my decisions.

JJ

On 3/6/21 1:13 PM, Kenn Sebesta wrote:

The genius of all this is that as battery tech improves the existing plane just gets better and better. When you're looking at your replacement pack 5-10 years down the road you'll automatically benefit from all the improvements and your new pack will either be cheaper, or it'll fly longer, or it'll be lighter. Maybe all three. Certainly never saw 100LL get cheaper, better, and lighter!


Well, ten years ago the FES folks came out with with their Gen 1
batteries featuring 2.1 kWhr of capacity. Now we're up to Gen 2,
featuring a walloping 2.1 kWhr. See how much improvement there's been?
They did manage to take the metal filings out of the packs, so yeah I
guess they did get a little lighter.

Wonder if Nadler has ripped the batteries out of his 15 year old wings
and put in super cells to make an Antares Turbo? I'm guessing not.

So do people buying a self launcher only want to do a 1K' launch? The
guy in Connecticut thought he'd dip into the "excess capacity" somebody
was talking about, and squeak back to the airport at rooftop level.
Unfortunately he found himself below rooftop level in no time flat.

On Thursday, March 11, 2021 at 1:49:45 PM UTC+10, kinsell wrote:
On 3/6/21 1:13 PM, Kenn Sebesta wrote:

The genius of all this is that as battery tech improves the existing plane just gets better and better. When you're looking at your replacement pack 5-10 years down the road you'll automatically benefit from all the improvements and your new pack will either be cheaper, or it'll fly longer, or it'll be lighter. Maybe all three. Certainly never saw 100LL get cheaper, better, and lighter!


Well, ten years ago the FES folks came out with with their Gen 1
batteries featuring 2.1 kWhr of capacity. Now we're up to Gen 2,
featuring a walloping 2.1 kWhr. See how much improvement there's been?
They did manage to take the metal filings out of the packs, so yeah I
guess they did get a little lighter.

Wonder if Nadler has ripped the batteries out of his 15 year old wings
and put in super cells to make an Antares Turbo? I'm guessing not.

So do people buying a self launcher only want to do a 1K' launch? The
guy in Connecticut thought he'd dip into the "excess capacity" somebody
was talking about, and squeak back to the airport at rooftop level.
Unfortunately he found himself below rooftop level in no time flat.

They're onto GEN3 now:
The GEN3 53Ah / 5.5kWh packs have 32% more energy in a package 13% larger.
The GEN3 70Ah / 7.7kWh packs have 85% more energy in a package 25% larger.