Electric Winch Project [Archive]

Dan Marotta

September 2nd 18, 04:15 PM

Didn't the German winch require being hooked up to the electrical grid?Â*
It seems the one currently under discussion would be self contained and
portable (on the back of a truck).

On 9/2/2018 7:48 AM, wrote:
> On Sunday, September 2, 2018 at 7:43:29 AM UTC-5, gotovkotzepkoi wrote:
>> Germans have had an electric winch for a long time. Nothing now. Don't
>> hold your breath for one built in the US. Won't happen. Charge with an
>> internal combustion engine? What's the point? Why not just use a piston
>> engine for the winch then?
>>
>>
>>
>>
>> --
>> gotovkotzepkoi
> Dear goto, I listened to Bill Daniels' presentation on his new electric winch at Reno and was highly impressed with the innovative and technically convincing design and features. As a German trained engineer and someone who has done thousands of winch launches of gliders and who was trained on a winch my hopes are high that this project is successful. The Bill Daniels winch allows for electric, diesel or gas powered versions, btw. Educate yourself before spewing off under a not-funny pseudonym!
> Herb

--
Dan, 5J

marco

September 2nd 18, 04:26 PM

The German winch can be found here: http://www.startwinde.de/
I know one club in the Netherlands using it. I only heared good comments. They have a battery pack on board and feedercables in the airfield, below the grass.

Martin Gregorie[_6_]

September 2nd 18, 06:57 PM

On Sun, 02 Sep 2018 09:15:40 -0600, Dan Marotta wrote:

> Didn't the German winch require being hooked up to the electrical grid?
> It seems the one currently under discussion would be self contained and
> portable (on the back of a truck).
>
All the electric winch designs I know about (and I assume the new US
design is similar) require three things: a power supply, a large electric
motor and a battery bank to act as a buffer between the first two items.

The German Electrowinde winch needs a 12-20 kw mains supply to feed a
220kw motor via its battery buffer, so the batteries aren't just for
decoration.

It seems to me that the winch motor and battery bank capacity will be
much the same whether the winch is configured as a towable trailer, on a
truck chassis or built into a permanent building: they all need the same
three part power train and it really doesn't matter whether the power
source is the mains, a COTS 12-12kw trailer generator parked alongside or
a truck with all three items installed on it.

A major issue for a mains-powered electric winch, in the UK anyway, is
the cost of cabling the airfield. We looked at it some years back: there
are four places were we put our winch - normally on one end of 04/22 and
less often on one end of 16/34 (obviously this is wind dependent), so
we'd need to wire up all four points on the field with buried cables, and
the winch points for 34 and 22 are both around 1km from the club house
and hence the nearest mains supply. Wiring our airfield would be quite
expensive. Consequently, we've gone with a Skylaunch running on LPG
(cheap and environmentally benign fuel). And we already had the tractor
used to move it between garage and the day's winchpoint.

> What's the point? Why not just use a piston engine for the winch then?
>
Because a (much) smaller engine driving a generator to keep the battery
bank topped up is probably more economical to run than a socking great V8
being running intermittently at high power, particularly when you include
the cost of wear and tear from temperature-cycling the big engine.

--
Martin | martin at
Gregorie | gregorie dot org

Chris Rowland[_2_]

September 2nd 18, 09:37 PM

At 17:57 02 September 2018, Martin Gregorie wrote:
>On Sun, 02 Sep 2018 09:15:40 -0600, Dan Marotta wrote:
>
>> Didn't the German winch require being hooked up to the electrical grid?
>> It seems the one currently under discussion would be self contained and
>> portable (on the back of a truck).
>>
>All the electric winch designs I know about (and I assume the new US
>design is similar) require three things: a power supply, a large electric

>motor and a battery bank to act as a buffer between the first two items.
>
>The German Electrowinde winch needs a 12-20 kw mains supply to feed a
>220kw motor via its battery buffer, so the batteries aren't just for
>decoration.
>
>It seems to me that the winch motor and battery bank capacity will be
>much the same whether the winch is configured as a towable trailer, on a
>truck chassis or built into a permanent building: they all need the same
>three part power train and it really doesn't matter whether the power
>source is the mains, a COTS 12-12kw trailer generator parked alongside or

>a truck with all three items installed on it.
>
>A major issue for a mains-powered electric winch, in the UK anyway, is
>the cost of cabling the airfield. We looked at it some years back: there
>are four places were we put our winch - normally on one end of 04/22 and
>less often on one end of 16/34 (obviously this is wind dependent), so
>we'd need to wire up all four points on the field with buried cables, and

>the winch points for 34 and 22 are both around 1km from the club house
>and hence the nearest mains supply. Wiring our airfield would be quite
>expensive. Consequently, we've gone with a Skylaunch running on LPG
>(cheap and environmentally benign fuel). And we already had the tractor
>used to move it between garage and the day's winchpoint.
>
>> What's the point? Why not just use a piston engine for the winch then?
>>
>Because a (much) smaller engine driving a generator to keep the battery
>bank topped up is probably more economical to run than a socking great V8

>being running intermittently at high power, particularly when you include

>the cost of wear and tear from temperature-cycling the big engine.
>
>
>--
>Martin | martin at
>Gregorie | gregorie dot org

I hear there's an electric winch at the gliding club at Unterwossen in
Germany. AIUI it is very fixed - in a concrete bunker. The site is in a
valley on the edge of the Alps so launching is always in the same
direction.

I've wondered if the best way to launch is by gravity, a weight falling
into a mine shaft and attached to the glider by a cable. If you have a
supply of water then the weight is by filling a tank. At the end of the
launch you dump the water, pull the much lighter tank back up, then refill
it. Given enough room you could have a circular airfield round the mine
shaft. The only energy that you need to supply is to retrieve the tank and
cable.

A few things to sort out but it's a start.

Chris

September 2nd 18, 09:58 PM

On Sunday, September 2, 2018 at 5:43:29 AM UTC-7, gotovkotzepkoi wrote:
> Germans have had an electric winch for a long time. Nothing now. Don't
> hold your breath for one built in the US. Won't happen. Charge with an
> internal combustion engine? What's the point? Why not just use a piston
> engine for the winch then?
>
>
>
>
> --
> gotovkotzepkoi

It is why all locomotives are diesel-electric: you get full torque at zero RPM, no transmission is required, and line tension and acceleration are easily controlled. Of course, the engine can be much smaller as the winch time is a small percentage of clock time.

Tom

Skypilot

September 2nd 18, 10:08 PM

I find all this stuff sexy, in Australia we all live in a bit of a fantasy of energy, we export our LPG, Coal and Oil like it’s going out of fashion and the “green” movements of our parties ensure that subsidies and grants are available to clubs and organisations for being green. My home club of Kingaroy would be a perfect site to go for a huge grant for four elec whinches 2xmain and 2x retrieve. The runway area is 2000m x100m of grass right next to a bitumen runway, there is power available within 200m of both winch sites. The only problem is the fact that it’s a certified runway with probably 1-2 private movements per hour, so the local Shire council are unlikely to approve winching. It’s a pity as there is a coal mine 20km away and there is a planned coal mine next to the airstrip and we have elections soon. If there was ever a time to pitch an alternative to burning smelly dinosaur bones and reducing the noise foot print for our solar powered sport now is it:)

I guess the panacea is to have an electric winch next to a battery bank powered by solar panels. In Australia this is feesable given the space and sunshine, BUT here is the crux - it’s battery technology.

The future will have elec self launch gliders, elec tow planes, elec winches and all of this will be powered by a battery system that is dual use. The batteries will be in runway edges, house bricks and other structural items not just a battery.

You will wake up in your house that is a storage facility hooked to the grid, most of the time you will be a next exporter of energy.

Jump in your electric car and drive up to the field.

Unplug your elec self launch Libelle and plug your car in, your hangar will have a storage battery bank in the wall bricks.

Tow your glider out to the runway with your elec golf cart and launch into the wild blue yonder with your retractable self launch system with prop goverening.

Once airborne you will go find a big fat thermal and redeploy your self launch prop mast and reverse the prop to recharge your batteries thereby extending your range.

The next type of comps will be range comps that will allow much greater distances and speeds, perhaps one day we will see solar panels on wings that can feed power to the battery system built into the composite fibres.

Fly until sunset and head to the clubhouse for a beer.

I just don’t understand why so many on here are negative to people trying to improve things, because let’s face it if we don’t improve things our sport is dead.

Justin

;975440']On Sun, 02 Sep 2018 09:15:40 -0600, Dan Marotta wrote:

Didn't the German winch require being hooked up to the electrical grid?
It seems the one currently under discussion would be self contained and
portable (on the back of a truck).

All the electric winch designs I know about (and I assume the new US
design is similar) require three things: a power supply, a large electric
motor and a battery bank to act as a buffer between the first two items.

The German Electrowinde winch needs a 12-20 kw mains supply to feed a
220kw motor via its battery buffer, so the batteries aren't just for
decoration.

It seems to me that the winch motor and battery bank capacity will be
much the same whether the winch is configured as a towable trailer, on a
truck chassis or built into a permanent building: they all need the same
three part power train and it really doesn't matter whether the power
source is the mains, a COTS 12-12kw trailer generator parked alongside or
a truck with all three items installed on it.

A major issue for a mains-powered electric winch, in the UK anyway, is
the cost of cabling the airfield. We looked at it some years back: there
are four places were we put our winch - normally on one end of 04/22 and
less often on one end of 16/34 (obviously this is wind dependent), so
we'd need to wire up all four points on the field with buried cables, and
the winch points for 34 and 22 are both around 1km from the club house
and hence the nearest mains supply. Wiring our airfield would be quite
expensive. Consequently, we've gone with a Skylaunch running on LPG
(cheap and environmentally benign fuel). And we already had the tractor
used to move it between garage and the day's winchpoint.

What's the point? Why not just use a piston engine for the winch then?

Because a (much) smaller engine driving a generator to keep the battery
bank topped up is probably more economical to run than a socking great V8
being running intermittently at high power, particularly when you include
the cost of wear and tear from temperature-cycling the big engine.

--
Martin | martin at
Gregorie | gregorie dot org

September 2nd 18, 10:20 PM

On Sunday, September 2, 2018 at 8:43:29 AM UTC-4, gotovkotzepkoi wrote:
> Germans have had an electric winch for a long time. Nothing now. Don't
> hold your breath for one built in the US. Won't happen. Charge with an
> internal combustion engine? What's the point? Why not just use a piston
> engine for the winch then?
>
>
>
>
> --
> gotovkotzepkoi

Hi Goto,

oh my god! Let's not do something new! Lets not leave the beaten path!
That's exactly how we ended up with planes still powered by '30s technology - no progress there for decades.
As Herb said, Bill's design and development is a huge step forward and it should be supported by the US-soaring community because it will make a difference in the future!

Uli
'AS'

September 2nd 18, 10:32 PM

On Sunday, September 2, 2018 at 11:15:43 AM UTC-4, Dan Marotta wrote:
> Didn't the German winch require being hooked up to the electrical grid?Â*
> It seems the one currently under discussion would be self contained and
> portable (on the back of a truck).
>

> Dan, 5J

Hi Dan,

the Elektostart winch in Germany has 50 starter batteries on board which supplied the bulk of the current during the launch. Since the electric infrastructure is so much more densely developed in Europe, it is never too far to the next power tie-in. A relatively low Amp connection is all that's needed to recharge the batteries between launches. Some clubs operating this winch trenched a cable to either end of their field and just plug it in.
The early Elektrostart winches had some issues with the software for the controller, which - if I remember correctly - was an industrial VFD. There were some instances reported where the controller couldn't cope with line tension oscillations but that is all worked out now.
As much as I like the winch I built for my club - powered by one kick-a$$ Ford 460 BB - electric drive is the way of the future!

Uli
'AS'

Dan Marotta

September 2nd 18, 10:35 PM

....and haul/pump the water.

On 9/2/2018 2:37 PM, Chris Rowland wrote:
> At 17:57 02 September 2018, Martin Gregorie wrote:
>> On Sun, 02 Sep 2018 09:15:40 -0600, Dan Marotta wrote:
>>
>>> Didn't the German winch require being hooked up to the electrical grid?
>>> It seems the one currently under discussion would be self contained and
>>> portable (on the back of a truck).
>>>
>> All the electric winch designs I know about (and I assume the new US
>> design is similar) require three things: a power supply, a large electric
>> motor and a battery bank to act as a buffer between the first two items.
>>
>> The German Electrowinde winch needs a 12-20 kw mains supply to feed a
>> 220kw motor via its battery buffer, so the batteries aren't just for
>> decoration.
>>
>> It seems to me that the winch motor and battery bank capacity will be
>> much the same whether the winch is configured as a towable trailer, on a
>> truck chassis or built into a permanent building: they all need the same
>> three part power train and it really doesn't matter whether the power
>> source is the mains, a COTS 12-12kw trailer generator parked alongside or
>> a truck with all three items installed on it.
>>
>> A major issue for a mains-powered electric winch, in the UK anyway, is
>> the cost of cabling the airfield. We looked at it some years back: there
>> are four places were we put our winch - normally on one end of 04/22 and
>> less often on one end of 16/34 (obviously this is wind dependent), so
>> we'd need to wire up all four points on the field with buried cables, and
>> the winch points for 34 and 22 are both around 1km from the club house
>> and hence the nearest mains supply. Wiring our airfield would be quite
>> expensive. Consequently, we've gone with a Skylaunch running on LPG
>> (cheap and environmentally benign fuel). And we already had the tractor
>> used to move it between garage and the day's winchpoint.
>>
>>> What's the point? Why not just use a piston engine for the winch then?
>>>
>> Because a (much) smaller engine driving a generator to keep the battery
>> bank topped up is probably more economical to run than a socking great V8
>> being running intermittently at high power, particularly when you include
>> the cost of wear and tear from temperature-cycling the big engine.
>>
>>
>> --
>> Martin | martin at
>> Gregorie | gregorie dot org
> I hear there's an electric winch at the gliding club at Unterwossen in
> Germany. AIUI it is very fixed - in a concrete bunker. The site is in a
> valley on the edge of the Alps so launching is always in the same
> direction.
>
> I've wondered if the best way to launch is by gravity, a weight falling
> into a mine shaft and attached to the glider by a cable. If you have a
> supply of water then the weight is by filling a tank. At the end of the
> launch you dump the water, pull the much lighter tank back up, then refill
> it. Given enough room you could have a circular airfield round the mine
> shaft. The only energy that you need to supply is to retrieve the tank and
> cable.
>
> A few things to sort out but it's a start.
>
> Chris
>
>

--
Dan, 5J

Dan Marotta

September 2nd 18, 10:45 PM

I agree, Uli.

When Black Forest bought a small block Chevy winch from the Air Force
Academy.Â* I and a couple of others removed the engine and installed a
big block Chevy (454 cu. in.).Â* It was pretty healthy!

On 9/2/2018 3:32 PM, AS wrote:
> On Sunday, September 2, 2018 at 11:15:43 AM UTC-4, Dan Marotta wrote:
>> Didn't the German winch require being hooked up to the electrical grid?
>> It seems the one currently under discussion would be self contained and
>> portable (on the back of a truck).
>>
>> Dan, 5J
> Hi Dan,
>
> the Elektostart winch in Germany has 50 starter batteries on board which supplied the bulk of the current during the launch. Since the electric infrastructure is so much more densely developed in Europe, it is never too far to the next power tie-in. A relatively low Amp connection is all that's needed to recharge the batteries between launches. Some clubs operating this winch trenched a cable to either end of their field and just plug it in.
> The early Elektrostart winches had some issues with the software for the controller, which - if I remember correctly - was an industrial VFD. There were some instances reported where the controller couldn't cope with line tension oscillations but that is all worked out now.
> As much as I like the winch I built for my club - powered by one kick-a$$ Ford 460 BB - electric drive is the way of the future!
>
> Uli
> 'AS'

--
Dan, 5J

Bob Youngblood

September 2nd 18, 11:19 PM

On Sunday, September 2, 2018 at 8:43:29 AM UTC-4, gotovkotzepkoi wrote:
> Germans have had an electric winch for a long time. Nothing now. Don't
> hold your breath for one built in the US. Won't happen. Charge with an
> internal combustion engine? What's the point? Why not just use a piston
> engine for the winch then?
>
>
>
>
> --
> gotovkotzepkoi

I can tell you that the current starting load for a 430 hp electric motor is substantial. Don't know if they are using a soft start or something equal it takes a lot of power to start a 430 hp electric motor. The amp requirements are huge, interesting concept, huge electric requirements. Bob

Bob Youngblood

September 2nd 18, 11:22 PM

On Sunday, September 2, 2018 at 6:19:12 PM UTC-4, Bob Youngblood wrote:
> On Sunday, September 2, 2018 at 8:43:29 AM UTC-4, gotovkotzepkoi wrote:
> > Germans have had an electric winch for a long time. Nothing now. Don't
> > hold your breath for one built in the US. Won't happen. Charge with an
> > internal combustion engine? What's the point? Why not just use a piston
> > engine for the winch then?
> >
> >
> >
> >
> > --
> > gotovkotzepkoi
>
> I can tell you that the current starting load for a 430 hp electric motor is substantial. Don't know if they are using a soft start or something equal it takes a lot of power to start a 430 hp electric motor. The amp requirements are huge, interesting concept, huge electric requirements. Bob

Bob Youngblood

September 2nd 18, 11:23 PM

Martin Gregorie[_6_]

September 2nd 18, 11:31 PM

On Sun, 02 Sep 2018 20:37:24 +0000, Chris Rowland wrote:

> I've wondered if the best way to launch is by gravity, a weight falling
> into a mine shaft and attached to the glider by a cable. If you have a
> supply of water then the weight is by filling a tank. At the end of the
> launch you dump the water, pull the much lighter tank back up, then
> refill it. Given enough room you could have a circular airfield round
> the mine shaft. The only energy that you need to supply is to retrieve
> the tank and cable.
>
> A few things to sort out but it's a start
>
I like it!

Just get M C Escher to design the airfield and Bob's Your Uncle!

--
Martin | martin at
Gregorie | gregorie dot org

September 3rd 18, 12:05 AM

> > I can tell you that the current starting load for a 430 hp electric motor is substantial. Don't know if they are using a soft start or something equal it takes a lot of power to start a 430 hp electric motor. The amp requirements are huge, interesting concept, huge electric requirements. Bob
>
> I think it would take almost 1 mg to start a 430 hp electric motor DOL. Huge power requirement.

Bob - they are all using frequency controllers! These are not your on-off industrial motors used to power a belt conveyor or hammer-mill! Think electric cars ...
Uli
'AS'

[email protected]

September 3rd 18, 01:44 AM

> Just get M C Escher to design the airfield and Bob's Your Uncle!

I love it!

September 3rd 18, 01:58 AM

On Sunday, September 2, 2018 at 8:43:10 PM UTC-4, Skypilot wrote:
> I find all this stuff sexy, in Australia we all live in a bit of a
> fantasy of energy, we export our LPG, Coal and Oil like it’s going
> out of fashion and the “green” movements of our parties
> ensure that subsidies and grants are available to clubs and
> organisations for being green. My home club of Kingaroy would be a
> perfect site to go for a huge grant for four elec whinches 2xmain and 2x
> retrieve. The runway area is 2000m x100m of grass right next to a
> bitumen runway, there is power available within 200m of both winch
> sites. The only problem is the fact that it’s a certified runway
> with probably 1-2 private movements per hour, so the local Shire council
> are unlikely to approve winching. It’s a pity as there is a coal
> mine 20km away and there is a planned coal mine next to the airstrip and
> we have elections soon. If there was ever a time to pitch an alternative
> to burning smelly dinosaur bones and reducing the noise foot print for
> our solar powered sport now is it:)
>
> I guess the panacea is to have an electric winch next to a battery bank
> powered by solar panels. In Australia this is feesable given the space
> and sunshine, BUT here is the crux - it’s battery technology.
>
> The future will have elec self launch gliders, elec tow planes, elec
> winches and all of this will be powered by a battery system that is dual
> use. The batteries will be in runway edges, house bricks and other
> structural items not just a battery.
>
> You will wake up in your house that is a storage facility hooked to the
> grid, most of the time you will be a next exporter of energy.
>
> Jump in your electric car and drive up to the field.
>
> Unplug your elec self launch Libelle and plug your car in, your hangar
> will have a storage battery bank in the wall bricks.
>
> Tow your glider out to the runway with your elec golf cart and launch
> into the wild blue yonder with your retractable self launch system with
> prop goverening.
>
> Once airborne you will go find a big fat thermal and redeploy your self
> launch prop mast and reverse the prop to recharge your batteries thereby
> extending your range.
>
> The next type of comps will be range comps that will allow much greater
> distances and speeds, perhaps one day we will see solar panels on wings
> that can feed power to the battery system built into the composite
> fibres.
>
> Fly until sunset and head to the clubhouse for a beer.
>
> I just don’t understand why so many on here are negative to people
> trying to improve things, because let’s face it if we don’t
> improve things our sport is dead.
>
> Justin
> --
> Skypilot

Amen to that, Justin! You hit the nail squarely on the head!

Uli
'AS'

September 3rd 18, 02:29 AM

You bunch of electric sissies! I want a glider with a huge freakin pulse jet strapped to it burning heavy crude or coal tar, throwing fire out the back for half a mile, sounding like Gabriel has jacked his trumpet into an amplifier powered by relativistic jets from a supermassive black hole.

Bob Youngblood

September 3rd 18, 02:47 AM

On Sunday, September 2, 2018 at 7:05:28 PM UTC-4, AS wrote:
> > > I can tell you that the current starting load for a 430 hp electric motor is substantial. Don't know if they are using a soft start or something equal it takes a lot of power to start a 430 hp electric motor. The amp requirements are huge, interesting concept, huge electric requirements. Bob
> >
> > I think it would take almost 1 mg to start a 430 hp electric motor DOL. Huge power requirement.
>
> Bob - they are all using frequency controllers! These are not your on-off industrial motors used to power a belt conveyor or hammer-mill! Think electric cars ...
> Uli
> 'AS'

Even with a VFD the electrical requirement is huge. Bob

joesimmers[_2_]

September 3rd 18, 02:32 PM

Some very nice High Quality work you guys are doing
on this project! Look forward to seeing finished working winch.

Dan Marotta

September 3rd 18, 03:37 PM

That was a pretty interesting bit of science fiction.Â* And the
proceeding was not meant as criticism, only that most of the mentioned
technology is so far into the future that most, if not all of us will
never see it.

My one criticism is not acknowledging that it takes power to make power
(currently) and using a propeller to drive a motor/generator in flight
will create a LOT of drag which translates directly into sink rate.Â*
There's no free lunch yet, except in California.

On 9/2/2018 3:08 PM, Skypilot wrote:
> I find all this stuff sexy, in Australia we all live in a bit of a
> fantasy of energy, we export our LPG, Coal and Oil like it’s going
> out of fashion and the “green” movements of our parties
> ensure that subsidies and grants are available to clubs and
> organisations for being green. My home club of Kingaroy would be a
> perfect site to go for a huge grant for four elec whinches 2xmain and 2x
> retrieve. The runway area is 2000m x100m of grass right next to a
> bitumen runway, there is power available within 200m of both winch
> sites. The only problem is the fact that it’s a certified runway
> with probably 1-2 private movements per hour, so the local Shire council
> are unlikely to approve winching. It’s a pity as there is a coal
> mine 20km away and there is a planned coal mine next to the airstrip and
> we have elections soon. If there was ever a time to pitch an alternative
> to burning smelly dinosaur bones and reducing the noise foot print for
> our solar powered sport now is it:)
>
> I guess the panacea is to have an electric winch next to a battery bank
> powered by solar panels. In Australia this is feesable given the space
> and sunshine, BUT here is the crux - it’s battery technology.
>
> The future will have elec self launch gliders, elec tow planes, elec
> winches and all of this will be powered by a battery system that is dual
> use. The batteries will be in runway edges, house bricks and other
> structural items not just a battery.
>
> You will wake up in your house that is a storage facility hooked to the
> grid, most of the time you will be a next exporter of energy.
>
> Jump in your electric car and drive up to the field.
>
> Unplug your elec self launch Libelle and plug your car in, your hangar
> will have a storage battery bank in the wall bricks.
>
> Tow your glider out to the runway with your elec golf cart and launch
> into the wild blue yonder with your retractable self launch system with
> prop goverening.
>
> Once airborne you will go find a big fat thermal and redeploy your self
> launch prop mast and reverse the prop to recharge your batteries thereby
> extending your range.
>
> The next type of comps will be range comps that will allow much greater
> distances and speeds, perhaps one day we will see solar panels on wings
> that can feed power to the battery system built into the composite
> fibres.
>
> Fly until sunset and head to the clubhouse for a beer.
>
> I just don’t understand why so many on here are negative to people
> trying to improve things, because let’s face it if we don’t
> improve things our sport is dead.
>
> Justin
>
>
>
>
> 'Martin Gregorie[_6_ Wrote:
>> ;975440']On Sun, 02 Sep 2018 09:15:40 -0600, Dan Marotta wrote:
>> -
>> Didn't the German winch require being hooked up to the electrical grid?
>> It seems the one currently under discussion would be self contained and
>> portable (on the back of a truck).
>> -
>> All the electric winch designs I know about (and I assume the new US
>> design is similar) require three things: a power supply, a large
>> electric
>> motor and a battery bank to act as a buffer between the first two items.
>>
>>
>> The German Electrowinde winch needs a 12-20 kw mains supply to feed a
>> 220kw motor via its battery buffer, so the batteries aren't just for
>> decoration.
>>
>> It seems to me that the winch motor and battery bank capacity will be
>> much the same whether the winch is configured as a towable trailer, on a
>>
>> truck chassis or built into a permanent building: they all need the same
>>
>> three part power train and it really doesn't matter whether the power
>> source is the mains, a COTS 12-12kw trailer generator parked alongside
>> or
>> a truck with all three items installed on it.
>>
>> A major issue for a mains-powered electric winch, in the UK anyway, is
>> the cost of cabling the airfield. We looked at it some years back: there
>>
>> are four places were we put our winch - normally on one end of 04/22 and
>>
>> less often on one end of 16/34 (obviously this is wind dependent), so
>> we'd need to wire up all four points on the field with buried cables,
>> and
>> the winch points for 34 and 22 are both around 1km from the club house
>> and hence the nearest mains supply. Wiring our airfield would be quite
>> expensive. Consequently, we've gone with a Skylaunch running on LPG
>> (cheap and environmentally benign fuel). And we already had the tractor
>> used to move it between garage and the day's winchpoint.
>> -
>> What's the point? Why not just use a piston engine for the winch then?
>> -
>> Because a (much) smaller engine driving a generator to keep the battery
>> bank topped up is probably more economical to run than a socking great
>> V8
>> being running intermittently at high power, particularly when you
>> include
>> the cost of wear and tear from temperature-cycling the big engine.
>>
>>
>> --
>> Martin | martin at
>> Gregorie | gregorie dot org
>
>
>

--
Dan, 5J

Chris Rowland[_2_]

September 3rd 18, 07:13 PM

At 21:35 02 September 2018, Dan Marotta wrote:
>....and haul/pump the water.
>
It comes in rivers and streams, pumped up for free by the sun.
Just open a sluice.

Gliders are fusion powered, this extends that to the launch.

Chris

Chris Rowland[_2_]

September 3rd 18, 07:15 PM

Chris Rowland[_2_]

September 3rd 18, 07:43 PM

At 01:47 03 September 2018, Bob Youngblood wrote:
>On Sunday, September 2, 2018 at 7:05:28 PM UTC-4, AS wrote:
>> > > I can tell you that the current starting load for a 430 hp
electric
>=
>motor is substantial. Don't know if they are using a soft start or
>somethin=
>g equal it takes a lot of power to start a 430 hp electric motor. The amp
>r=
>equirements are huge, interesting concept, huge electric requirements.
Bob
>> >=20
>> > I think it would take almost 1 mg to start a 430 hp electric motor
>DOL.=
> Huge power requirement.
>>=20
>> Bob - they are all using frequency controllers! These are not your
>on-off=
> industrial motors used to power a belt conveyor or hammer-mill! Think
>elec=
>tric cars ...
>> Uli
>> 'AS'
>
>Even with a VFD the electrical requirement is huge. Bob
>
There are a lot of high power electrical systems around, trains for
example. Underground trains in particular.

Chris

Charlie M. (UH & 002 owner/pilot)

September 3rd 18, 08:10 PM

Many posts to reply to, I pick yours since new.......

Bad enough for a glider operation to shar an airport with powered craft whether the field has US Federal funding or not.
Then add in digging stuff up to run power lines to either run an electric winch or charge batteries at some decent rate.

I "believe" our private owned, public use, federally funded airfield has most income from the glider operation. This does not mean we can do whatever.

Income is......
Towplane gas use.
At least one hanger.
Tie downs.
TO/landings.
Etc.

I have flown there for OVER 40 years. Look up Steve Bennis, I believe he started the airport, is in the Soaring Hall of Fame, etc. He gave me my pvt and cml glider checkrides.

Digging up the field is still likely a hassle with the current owner to run power lines.

If you can do it, great, pat on the back.

Skypilot

September 3rd 18, 10:06 PM

Hi Dan, all understood, all of the technology is here now other than the small high capacitance cheap batteries. We have Tesla’s, GP15’s, self launch Libelle’s and in my and your country lots of sunshine. In fact one of our club legends who has been gliding for 65 years drove his new Tesla to the club the other day from 220km away. It took two days to recharge on the club mains power :)
I totally agree about the power and am the biggest supporter of nuclear power but we shall leave that for another day. The prop drag is only related to the torque attached to it, RATS have been around for ages, a goverener in the prop hub will load up the elec motor and via reverese current charge the battery, cleverer people than me will guess but it will probably have to be a 4kt thermal or so. It will all come down to the batteries and the various authorities allowing it to take place. You will probably still have a power bill to pay for the grid to allow society to function.

[QUOTE=Dan Marotta;975487]That was a pretty interesting bit of science fiction.Â* And the
proceeding was not meant as criticism, only that most of the mentioned
technology is so far into the future that most, if not all of us will
never see it.

My one criticism is not acknowledging that it takes power to make power
(currently) and using a propeller to drive a motor/generator in flight
will create a LOT of drag which translates directly into sink rate.Â*
There's no free lunch yet, except in California.

On 9/2/2018 3:08 PM, Skypilot wrote:[color=blue][i]
I find all this stuff sexy, in Australia we all live in a bit of a
fantasy of energy, we export our LPG, Coal and Oil like it’s going
out of fashion and the “green” movements of our parties
ensure that subsidies and grants are available to clubs and
organisations for being green. My home club of Kingaroy would be a
perfect site to go for a huge grant for four elec whinches 2xmain and 2x
retrieve. The runway area is 2000m x100m of grass right next to a
bitumen runway, there is power available within 200m of both winch
sites. The only problem is the fact that it’s a certified runway
with probably 1-2 private movements per hour, so the local Shire council
are unlikely to approve winching. It’s a pity as there is a coal
mine 20km away and there is a planned coal mine next to the airstrip and
we have elections soon. If there was ever a time to pitch an alternative
to burning smelly dinosaur bones and reducing the noise foot print for
our solar powered sport now is it:)

I guess the panacea is to have an electric winch next to a battery bank
powered by solar panels. In Australia this is feesable given the space
and sunshine, BUT here is the crux - it’s battery technology.

The future will have elec self launch gliders, elec tow planes, elec
winches and all of this will be powered by a battery system that is dual
use. The batteries will be in runway edges, house bricks and other
structural items not just a battery.

You will wake up in your house that is a storage facility hooked to the
grid, most of the time you will be a next exporter of energy.

Jump in your electric car and drive up to the field.

Unplug your elec self launch Libelle and plug your car in, your hangar
will have a storage battery bank in the wall bricks.

Tow your glider out to the runway with your elec golf cart and launch
into the wild blue yonder with your retractable self launch system with
prop goverening.

Once airborne you will go find a big fat thermal and redeploy your self
launch prop mast and reverse the prop to recharge your batteries thereby
extending your range.

The next type of comps will be range comps that will allow much greater
distances and speeds, perhaps one day we will see solar panels on wings
that can feed power to the battery system built into the composite
fibres.

Fly until sunset and head to the clubhouse for a beer.

I just don’t understand why so many on here are negative to people
trying to improve things, because let’s face it if we don’t
improve things our sport is dead.

Justin

[email protected]

September 3rd 18, 10:30 PM

I suspect the challenges associated with digging and maintaining the 1km deep holes at each end of the runway might get in the way of an otherwise excellent idea! You could of course make them shallower with some pulley's but I think that would interfere with the aesthetic simplicity of the idea.

Mark.

On Monday, September 3, 2018 at 6:45:05 AM UTC+10, Chris Rowland wrote:
>
> I've wondered if the best way to launch is by gravity, a weight falling
> into a mine shaft and attached to the glider by a cable. If you have a
> supply of water then the weight is by filling a tank. At the end of the
> launch you dump the water, pull the much lighter tank back up, then refill
> it. Given enough room you could have a circular airfield round the mine
> shaft. The only energy that you need to supply is to retrieve the tank and
> cable.
>
> A few things to sort out but it's a start.
>
> Chris

September 4th 18, 01:56 AM

On Sunday, September 2, 2018 at 9:29:48 PM UTC-4, WB wrote:
> You bunch of electric sissies! I want a glider with a huge freakin pulse jet strapped to it burning heavy crude or coal tar, throwing fire out the back for half a mile, sounding like Gabriel has jacked his trumpet into an amplifier powered by relativistic jets from a supermassive black hole.

Wow - that sound dark and apocalyptic! ;-)

Uli
'AS'

Dan Marotta

September 4th 18, 03:00 PM

I like the way you think! :-D

Dan

On 9/3/2018 3:06 PM, Skypilot wrote:
> Hi Dan, all understood, all of the technology is here now other than the
> small high capacitance cheap batteries. We have Tesla’s,
> GP15’s, self launch Libelle’s and in my and your country
> lots of sunshine. In fact one of our club legends who has been gliding
> for 65 years drove his new Tesla to the club the other day from 220km
> away. It took two days to recharge on the club mains power :)
> I totally agree about the power and am the biggest supporter of nuclear
> power but we shall leave that for another day. The prop drag is only
> related to the torque attached to it, RATS have been around for ages, a
> goverener in the prop hub will load up the elec motor and via reverese
> current charge the battery, cleverer people than me will guess but it
> will probably have to be a 4kt thermal or so. It will all come down to
> the batteries and the various authorities allowing it to take place. You
> will probably still have a power bill to pay for the grid to allow
> society to function.
>
> Dan Marotta;975487 Wrote:
>> That was a pretty interesting bit of science fiction.Ã‚* And the
>> proceeding was not meant as criticism, only that most of the mentioned
>> technology is so far into the future that most, if not all of us will
>> never see it.
>>
>> My one criticism is not acknowledging that it takes power to make power
>> (currently) and using a propeller to drive a motor/generator in flight
>> will create a LOT of drag which translates directly into sink rate.Ã‚*
>> There's no free lunch yet, except in California.
>>
>> On 9/2/2018 3:08 PM, Skypilot wrote:[color=blue][i]
>> I find all this stuff sexy, in Australia we all live in a bit of a
>> fantasy of energy, we export our LPG, Coal and Oil like it’s
>> going
>> out of fashion and the “green” movements of our parties
>> ensure that subsidies and grants are available to clubs and
>> organisations for being green. My home club of Kingaroy would be a
>> perfect site to go for a huge grant for four elec whinches 2xmain and
>> 2x
>> retrieve. The runway area is 2000m x100m of grass right next to a
>> bitumen runway, there is power available within 200m of both winch
>> sites. The only problem is the fact that it’s a certified runway
>> with probably 1-2 private movements per hour, so the local Shire
>> council
>> are unlikely to approve winching. It’s a pity as there is a coal
>> mine 20km away and there is a planned coal mine next to the airstrip
>> and
>> we have elections soon. If there was ever a time to pitch an
>> alternative
>> to burning smelly dinosaur bones and reducing the noise foot print for
>> our solar powered sport now is it:)
>>
>> I guess the panacea is to have an electric winch next to a battery bank
>> powered by solar panels. In Australia this is feesable given the space
>> and sunshine, BUT here is the crux - it’s battery technology.
>>
>> The future will have elec self launch gliders, elec tow planes, elec
>> winches and all of this will be powered by a battery system that is
>> dual
>> use. The batteries will be in runway edges, house bricks and other
>> structural items not just a battery.
>>
>> You will wake up in your house that is a storage facility hooked to the
>> grid, most of the time you will be a next exporter of energy.
>>
>> Jump in your electric car and drive up to the field.
>>
>> Unplug your elec self launch Libelle and plug your car in, your hangar
>> will have a storage battery bank in the wall bricks.
>>
>> Tow your glider out to the runway with your elec golf cart and launch
>> into the wild blue yonder with your retractable self launch system with
>> prop goverening.
>>
>> Once airborne you will go find a big fat thermal and redeploy your self
>> launch prop mast and reverse the prop to recharge your batteries
>> thereby
>> extending your range.
>>
>> The next type of comps will be range comps that will allow much greater
>> distances and speeds, perhaps one day we will see solar panels on wings
>> that can feed power to the battery system built into the composite
>> fibres.
>>
>> Fly until sunset and head to the clubhouse for a beer.
>>
>> I just don’t understand why so many on here are negative to
>> people
>> trying to improve things, because let’s face it if we don’t
>> improve things our sport is dead.
>>
>> Justin
>
>
>

--
Dan, 5J

kirk.stant

September 4th 18, 05:46 PM

On Sunday, September 2, 2018 at 8:29:48 PM UTC-5, WB wrote:
> You bunch of electric sissies! I want a glider with a huge freakin pulse jet strapped to it burning heavy crude or coal tar, throwing fire out the back for half a mile, sounding like Gabriel has jacked his trumpet into an amplifier powered by relativistic jets from a supermassive black hole.

Better still, Project Pluto...

66

JS[_5_]

September 4th 18, 06:30 PM

On Tuesday, September 4, 2018 at 9:46:56 AM UTC-7, kirk.stant wrote:
> On Sunday, September 2, 2018 at 8:29:48 PM UTC-5, WB wrote:
> > You bunch of electric sissies! I want a glider with a huge freakin pulse jet strapped to it burning heavy crude or coal tar, throwing fire out the back for half a mile, sounding like Gabriel has jacked his trumpet into an amplifier powered by relativistic jets from a supermassive black hole.
>
> Better still, Project Pluto...
>
> 66

The Diesel-Electric idea seems great.
It would be nice to run a winch where the noise of a big block V-8 doesn't drown out the singing of the rope.
Hardly science-fiction, as D-E engines brought an end to the steam age of trains in the 1960s.
Wishing the best results to all designing new stuff!
Jim

Chris Rowland[_2_]

September 4th 18, 06:56 PM

At 16:46 04 September 2018, kirk.stant wrote:
>On Sunday, September 2, 2018 at 8:29:48 PM UTC-5, WB wrote:
>> You bunch of electric sissies! I want a glider with a huge freakin
pulse
>=
>jet strapped to it burning heavy crude or coal tar, throwing fire out the
>b=
>ack for half a mile, sounding like Gabriel has jacked his trumpet into an
>a=
>mplifier powered by relativistic jets from a supermassive black hole.
>
>Better still, Project Pluto...
>
>66
>
There's always the Yak 110, two Yak55s bolted together with a jet engine.

https://www.youtube.com/watch?v=nWtOQ2nxDtE

Chris

[email protected]

September 6th 18, 02:12 AM

On Sunday, September 2, 2018 at 4:19:12 PM UTC-6, Bob Youngblood wrote:
> On Sunday, September 2, 2018 at 8:43:29 AM UTC-4, gotovkotzepkoi wrote:
> > Germans have had an electric winch for a long time. Nothing now. Don't
> > hold your breath for one built in the US. Won't happen. Charge with an
> > internal combustion engine? What's the point? Why not just use a piston
> > engine for the winch then?
> >
> >
> >
> >
> > --
> > gotovkotzepkoi
>

> I can tell you that the current starting load for a 430 hp electric motor is substantial. Don't know if they are using a soft start or something equal it takes a lot of power to start a 430 hp electric motor. The amp requirements are huge, interesting concept, huge electric requirements. Bob
-------------------

Bob, you are confused by old-school, garden variety synchronous AC induction motors which do require a lights dimming surge of power to get them up to synchronization with a fixed power line frequency. They're inefficient so they're largely been replaced by better technology. The tech is changing so fast it's hard to keep up.

The variable frequency motor (PMSM) used in the winch does not require such a surge to start. RPM is a function of frequency and torque is a function of current. The current it draws is proportional to the torque output required.

Variable frequency AC is provided by a "traction inverter" or VFD which very efficiently converts battery DC to 0 to ~1,000 Hz 3-phase AC. The motor starts gently at 0 Hz and smoothly revs up as the frequency is increased.

The battery is kept charged by a relative small power source which need only supply the average power demand over many launches. As designed, the winch will have far more than needed from a PTO driven generator but almost any source of electricity would do - even a 2,000 Sq Ft solar cell array would work handily.

Battery cost is already so low there is a minimal impact on the cost of the winch. We have quotes for a bigger than needed battery for less than $2,000 and prices are dropping very fast.

September 7th 18, 12:34 AM

I know battery powered winches benefiting from the automotive boom in motors and batteries is our future. But there's nothing like a big block engine roaring through a pair of open bog headers to get the hair standing up on your arms. Everyone within half a mile knows that the gods of combustion have arrived, and they are angry. The high pitched scream of a electric motor running on an inverter, just ain't the same.

Kudos to Bill for taking point on this, just remember the guys on point get shot at a lot.

SF

September 7th 18, 12:46 AM

On Thursday, September 6, 2018 at 7:34:36 PM UTC-4, SF wrote:
> I know battery powered winches benefiting from the automotive boom in motors and batteries is our future. But there's nothing like a big block engine roaring through a pair of open bog headers to get the hair standing up on your arms. Everyone within half a mile knows that the gods of combustion have arrived, and they are angry. The high pitched scream of a electric motor running on an inverter, just ain't the same.
>
> Kudos to Bill for taking point on this, just remember the guys on point get shot at a lot.
>
> SF

Scott is talking about this one:
https://www.youtube.com/watch?v=YePIJKs5me0
Make sure to have the volume cranked up.... :-)

Uli
'AS'

Charlie Quebec

September 9th 18, 03:13 AM

It is much easier to measure and control the line tension with an electric motor, eliminating the rocket launch a single seater can get when the winch driver has been
launching the training two seater all day. On my first flight in a Hornet on the winch, the acceleration was so great I could not prevent the glider from rotating immediately
with full forward stick, 5 terrifying seconds....

[email protected]

September 9th 18, 10:57 PM

On Saturday, September 8, 2018 at 8:13:44 PM UTC-6, Charlie Quebec wrote:
> It is much easier to measure and control the line tension with an electric motor, eliminating the rocket launch a single seater can get when the winch driver has been
> launching the training two seater all day. On my first flight in a Hornet on the winch, the acceleration was so great I could not prevent the glider from rotating immediately
> with full forward stick, 5 terrifying seconds....

Charlie, I just added a PDF "Project Overview" document to the web page which goes to some length explaining the control system. As in the OP, the page can be seen at www.hdelectriclaunch.com

[email protected]

September 10th 18, 09:35 AM

I saw make electric winches and put huge wind turbines next to them to recharge the batteries. The rule is simple, if you can land through the blades the launch is free.

[email protected]

September 10th 18, 11:23 AM

On Monday, September 10, 2018 at 2:35:03 AM UTC-6, wrote:
> I saw make electric winches and put huge wind turbines next to them to recharge the batteries. The rule is simple, if you can land through the blades the launch is free.

Free? How much did the winch cost? And did the wind turbine sprout from a magic bean?

[email protected]

September 10th 18, 11:51 AM

On Monday, September 10, 2018 at 12:23:26 PM UTC+2, wrote:
> On Monday, September 10, 2018 at 2:35:03 AM UTC-6, wrote:
> > I say make electric winches and put huge wind turbines next to them to recharge the batteries. The rule is simple, if you can land through the blades the launch is free.
>
> Free? How much did the winch cost? And did the wind turbine sprout from a magic bean?

It is considered good practice to read all sentences in a post before responding.

Martin Gregorie[_6_]

September 10th 18, 01:21 PM

On Mon, 10 Sep 2018 01:35:01 -0700, flybd5 wrote:

> I saw make electric winches and put huge wind turbines next to them to
> recharge the batteries.
>
Actually, the turbine would be fairly small.

A winch launch takes about 35 seconds from first movement until release
and about the maximum launch rate achievable with a two drum winch is 20
an hour , so the winch duty cycle is 20% at the most. If we assume the
winch burns a continuous 300kW during a launch (yes, that's probably a
large overestimate), then the average draw over an hour is 60kW - well
within the capability of a diesel trailer generator or a 22m diameter
three-blade wind turbine.

If the winch averages half power over the whole launch and the launch
rate is a more typical 10 an hour, the average power requirement drops to
15kW or a 9m diameter three-blade turbine.

> The rule is simple, if you can land through the blades the launch
> is free.
>
.... but an glider bigger than about 5m span would not fit through the
blades of a suitable turbine, even if it was stationary.

[1] Several years ago a bunch of us made periodic attempts to see how
high a launch rate was possible with a two drum diesel winch (Supacat).
We could hit 20 launches an hour, but never managed to exceed it, and
apart from the winch driver and launch marshal, we needed a full-time
driver in the cable retrieval truck, and another two people to collect
gliders as they landed, put them back on the dual launch queues, and keep
the launch queues moved up to the launch point. It didn't need much to
drop the rate either - an instructor who briefed when he and his student
reached the front of the queue, rather than one or two launches earlier
would do it.

--
Martin | martin at
Gregorie | gregorie dot org

[email protected]

September 10th 18, 03:57 PM

On Monday, September 10, 2018 at 6:21:06 AM UTC-6, Martin Gregorie wrote:
> On Mon, 10 Sep 2018 01:35:01 -0700, flybd5 wrote:
>
> > I saw make electric winches and put huge wind turbines next to them to
> > recharge the batteries.
> >
> Actually, the turbine would be fairly small.
>
> A winch launch takes about 35 seconds from first movement until release
> and about the maximum launch rate achievable with a two drum winch is 20
> an hour , so the winch duty cycle is 20% at the most. If we assume the
> winch burns a continuous 300kW during a launch (yes, that's probably a
> large overestimate), then the average draw over an hour is 60kW - well
> within the capability of a diesel trailer generator or a 22m diameter
> three-blade wind turbine.
>
> If the winch averages half power over the whole launch and the launch
> rate is a more typical 10 an hour, the average power requirement drops to
> 15kW or a 9m diameter three-blade turbine.
>
> > The rule is simple, if you can land through the blades the launch
> > is free.
> >
> ... but an glider bigger than about 5m span would not fit through the
> blades of a suitable turbine, even if it was stationary.
>
> [1] Several years ago a bunch of us made periodic attempts to see how
> high a launch rate was possible with a two drum diesel winch (Supacat).
> We could hit 20 launches an hour, but never managed to exceed it, and
> apart from the winch driver and launch marshal, we needed a full-time
> driver in the cable retrieval truck, and another two people to collect
> gliders as they landed, put them back on the dual launch queues, and keep
> the launch queues moved up to the launch point. It didn't need much to
> drop the rate either - an instructor who briefed when he and his student
> reached the front of the queue, rather than one or two launches earlier
> would do it.
>
>
> --
> Martin | martin at
> Gregorie | gregorie dot org

The numbers are simpler if one uses 1 - 2 kWh per launch (depends on glider weight and height of release) so 20 launches an hour would need a continuous 20 - 40 kW supply to maintain a steady-state battery charge. With a battery buffer, this supply can be very unsteady. The max power demand is not as important as long as the battery can deliver it.

40 kW is well within the range of various renewable sources. The incredible drop in solar panel prices make that a reasonable possibility. I estimate it would take about 2,500 sq. ft of them (~$25,000). One can imagine an accordion package which could be spread out on the ground near the winch.

While on the subject of dropping prices, Battery costs are dropping so fast that one can imagine a pack large enough for a whole day's winching. Recharging overnight from grid power simplifies the whole idea of an electric winch. Further imagine the winch mounted on an electric truck using the truck's enormous battery pack.

[email protected]

September 10th 18, 06:59 PM

Thanks, Dan. The guiding idea was simplicity but simplicity is a slippery thing. High levels of functionality often demand complexity. Einstein got it right when he said a thing should be as simple as possible - but no simpler.

On Monday, September 10, 2018 at 11:28:42 AM UTC-6, Dan Marotta wrote:
> I read your PDF on construction and operation of the winch.Â* And, though
> I'm an electrical and systems engineer, I'm really fascinated with the
> mechanical stuff and the design.Â* I thought it was very well done.
>
> On 9/10/2018 8:57 AM, wrote:
> > On Monday, September 10, 2018 at 6:21:06 AM UTC-6, Martin Gregorie wrote:
> >> On Mon, 10 Sep 2018 01:35:01 -0700, flybd5 wrote:
> >>
> >>> I saw make electric winches and put huge wind turbines next to them to
> >>> recharge the batteries.
> >>>
> >> Actually, the turbine would be fairly small.
> >>
> >> A winch launch takes about 35 seconds from first movement until release
> >> and about the maximum launch rate achievable with a two drum winch is 20
> >> an hour , so the winch duty cycle is 20% at the most. If we assume the
> >> winch burns a continuous 300kW during a launch (yes, that's probably a
> >> large overestimate), then the average draw over an hour is 60kW - well
> >> within the capability of a diesel trailer generator or a 22m diameter
> >> three-blade wind turbine.
> >>
> >> If the winch averages half power over the whole launch and the launch
> >> rate is a more typical 10 an hour, the average power requirement drops to
> >> 15kW or a 9m diameter three-blade turbine.
> >>
> >>> The rule is simple, if you can land through the blades the launch
> >>> is free.
> >>>
> >> ... but an glider bigger than about 5m span would not fit through the
> >> blades of a suitable turbine, even if it was stationary.
> >>
> >> [1] Several years ago a bunch of us made periodic attempts to see how
> >> high a launch rate was possible with a two drum diesel winch (Supacat)..
> >> We could hit 20 launches an hour, but never managed to exceed it, and
> >> apart from the winch driver and launch marshal, we needed a full-time
> >> driver in the cable retrieval truck, and another two people to collect
> >> gliders as they landed, put them back on the dual launch queues, and keep
> >> the launch queues moved up to the launch point. It didn't need much to
> >> drop the rate either - an instructor who briefed when he and his student
> >> reached the front of the queue, rather than one or two launches earlier
> >> would do it.
> >>
> >>
> >> --
> >> Martin | martin at
> >> Gregorie | gregorie dot org
> > The numbers are simpler if one uses 1 - 2 kWh per launch (depends on glider weight and height of release) so 20 launches an hour would need a continuous 20 - 40 kW supply to maintain a steady-state battery charge. With a battery buffer, this supply can be very unsteady. The max power demand is not as important as long as the battery can deliver it.
> >
> > 40 kW is well within the range of various renewable sources. The incredible drop in solar panel prices make that a reasonable possibility. I estimate it would take about 2,500 sq. ft of them (~$25,000). One can imagine an accordion package which could be spread out on the ground near the winch.
> >
> > While on the subject of dropping prices, Battery costs are dropping so fast that one can imagine a pack large enough for a whole day's winching. Recharging overnight from grid power simplifies the whole idea of an electric winch. Further imagine the winch mounted on an electric truck using the truck's enormous battery pack.
>
> --
> Dan, 5J