$1 billion BMS Ooops...

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.

Yep. There is a decision altitude below which the engine is no option anymore.

Le mercredi 10 mars 2021 Ã* 10:38:28 UTC+1, a écritÂ*:
On Wednesday, 10 March 2021 at 02:01:56 UTC, jfitch wrote:
JJ
A marginal final glide in a motor glider (FES perhaps excepted) is a final glide in a glider in my mind.

When considering outlanding options and engines, consider flying west
from Taos, NM:


Dan
5J

On 3/10/21 6:08 AM, Tango Whisky wrote:
Yep. There is a decision altitude below which the engine is no option anymore.

Le mercredi 10 mars 2021 Ã* 10:38:28 UTC+1, a écritÂ*:
On Wednesday, 10 March 2021 at 02:01:56 UTC, jfitch wrote:
JJ
A marginal final glide in a motor glider (FES perhaps excepted) is a final glide in a glider in my mind.

Someone said:

"Electric self-launchers seem particularly
well-suited to partnerships, with their easier use of the motor."

The contrary may be the case for electric gliders with removable batteries. At our airfield the electricity supply will not be adequate for the potential recharging requirements of more electric gliders. At the moment the only FES gliders at the club are individually owned, and the owners take the batteries home to charge them. The batteries of a syndicate owned glider would have to be charged on site - which will become a problem.

On a completely different point, I have been flying an ICE self-launcher for 14 years. I like to take off with sufficient fuel on board for a relight and a self-retrieve. I have rarely needed it, but if I didn't I would need to make road retrieve arrangements before cross country flights. I won't change to an electric glider until it has that sort of endurance - which is unlikely in my gliding lifetime.

Incidentally, twice in the 14 years I have landed in a field (safely, I am happy to say). The first time I initiated the start sequence at 1,000 foot on downwind, and the engine failed to start. The second time, I was on a marginal final glide, I took a clear decision to continue below a safe engine start height in the knowledge that there were safe fields on the way to the airfield, and when the final glide became too marginal I landed in a field without considering deploying the engine. Happily, I have never had to start the engine other than over a safe place to land.

On Thursday, March 11, 2021 at 10:42:32 AM UTC+10, waremark wrote:
Someone said:

"Electric self-launchers seem particularly
well-suited to partnerships, with their easier use of the motor."

The contrary may be the case for electric gliders with removable batteries. At our airfield the electricity supply will not be adequate for the potential recharging requirements of more electric gliders. At the moment the only FES gliders at the club are individually owned, and the owners take the batteries home to charge them. The batteries of a syndicate owned glider would have to be charged on site - which will become a problem.

On a completely different point, I have been flying an ICE self-launcher for 14 years. I like to take off with sufficient fuel on board for a relight and a self-retrieve. I have rarely needed it, but if I didn't I would need to make road retrieve arrangements before cross country flights. I won't change to an electric glider until it has that sort of endurance - which is unlikely in my gliding lifetime.

Incidentally, twice in the 14 years I have landed in a field (safely, I am happy to say). The first time I initiated the start sequence at 1,000 foot on downwind, and the engine failed to start. The second time, I was on a marginal final glide, I took a clear decision to continue below a safe engine start height in the knowledge that there were safe fields on the way to the airfield, and when the final glide became too marginal I landed in a field without considering deploying the engine. Happily, I have never had to start the engine other than over a safe place to land.

Is your airfield off-grid? How constrained is the capacity of your club's electricity connection that you wouldn't be able to handle charging gliders there? The FES chargers are 1200W, the Antares is similar. They seem to only charge at full current briefly and then start dropping down rapidly as the batteries approach full charge. Even with a single phase connection you should be fine for 12 gliders at max current simultaneously. I even charge my FES batteries off an inverter in my van (which has 2x135Ah Lithiums + 300W solar + 1000W inverter).

On Thursday, 11 March 2021 at 01:33:34 UTC, Matthew Scutter wrote:
On Thursday, March 11, 2021 at 10:42:32 AM UTC+10, waremark wrote:
Someone said:

"Electric self-launchers seem particularly
well-suited to partnerships, with their easier use of the motor."

The contrary may be the case for electric gliders with removable batteries. At our airfield the electricity supply will not be adequate for the potential recharging requirements of more electric gliders. At the moment the only FES gliders at the club are individually owned, and the owners take the batteries home to charge them. The batteries of a syndicate owned glider would have to be charged on site - which will become a problem.

On a completely different point, I have been flying an ICE self-launcher for 14 years. I like to take off with sufficient fuel on board for a relight and a self-retrieve. I have rarely needed it, but if I didn't I would need to make road retrieve arrangements before cross country flights. I won't change to an electric glider until it has that sort of endurance - which is unlikely in my gliding lifetime.

Incidentally, twice in the 14 years I have landed in a field (safely, I am happy to say). The first time I initiated the start sequence at 1,000 foot on downwind, and the engine failed to start. The second time, I was on a marginal final glide, I took a clear decision to continue below a safe engine start height in the knowledge that there were safe fields on the way to the airfield, and when the final glide became too marginal I landed in a field without considering deploying the engine. Happily, I have never had to start the engine other than over a safe place to land.
Is your airfield off-grid? How constrained is the capacity of your club's electricity connection that you wouldn't be able to handle charging gliders there? The FES chargers are 1200W, the Antares is similar. They seem to only charge at full current briefly and then start dropping down rapidly as the batteries approach full charge. Even with a single phase connection you should be fine for 12 gliders at max current simultaneously. I even charge my FES batteries off an inverter in my van (which has 2x135Ah Lithiums + 300W solar + 1000W inverter).

On grid - but of course we have a lot of draw for other purposes before people start charging gliders.

waremark wrote on 3/10/2021 4:42 PM:
On a completely different point, I have been flying an ICE self-launcher for 14 years. I like to take off with sufficient fuel on board for a relight and a self-retrieve.

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

--
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

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?