To Pawnee or not to Pawnee...that is the question...

On Oct 20, 9:45 am, "Bill Daniels" bildan@comcast-dot-net wrote:
I don't think any tow plane ever pays for itself once all 'hidden' costs are
considered. Operating an old rag and tube airplane of any kind is fraught
with 'nickel & dime' costs that add up. The last time I took a hard look, a
Pawnee runs about $150 USD/hour. With rapidly escalating costs of fuel and
insurance, it will probably be $200/hour by next summer. You don't operate
small airplanes to make money, you do it because you either need to or want
to. Tugs are cost centers not profit centers.

I think any club interested in lowering operating costs should be
investigating winches.

Bill Daniels

I forgot to add my "turbine tow would require winch launch
authorization" punch line. ;-) Thanks, Frank.

If somebody made a twin-turbine-taildragger tug, you could get the tow
pilots to PAY for that time (building time for th airlines...).
Turbine Beech-18 gets logged as Complex-Multi-Taildragger-Turbine-High
Performance time...worth $200.00 per hour for training to be a line
pilot. Yeah, I'd go back to the club and put up with the politics for
that!

Since AUTO fuel will quickly be over $4.00 per gallon (it already has
"traded" above that in Beverly Hills), the winches aren't going to be
a hell of a lot better -- if we must insist on suckering, er I mean
recruiting teenagers into our dying sport. (Flame away, guys...I'm
trying to get my kids interested -- _I_ have a hard time competing
with video games, even when I shut the power off).

I suspect we'll soon be back to hilltops and bungee cords... Quick,
we must assemble a protest march to SAVE TORREY PINES (Gliderport)!!!!

-Pete
#309
(I just donned my flame retardant suit).

P.S.: For the record, I agree with Bill -- EVERY "club" should have a
winch. And I think winch launches COULD compete with video games.

On Oct 20, 11:10 am, 309 wrote:
On Oct 20, 9:45 am, "Bill Daniels" bildan@comcast-dot-net wrote:

I don't think any tow plane ever pays for itself once all 'hidden' costs are
considered. Operating an old rag and tube airplane of any kind is fraught
with 'nickel & dime' costs that add up. The last time I took a hard look, a
Pawnee runs about $150 USD/hour. With rapidly escalating costs of fuel and
insurance, it will probably be $200/hour by next summer. You don't operate
small airplanes to make money, you do it because you either need to or want
to. Tugs are cost centers not profit centers.

I think any club interested in lowering operating costs should be
investigating winches.

Bill Daniels

I forgot to add my "turbine tow would require winch launch
authorization" punch line. ;-) Thanks, Frank.

If somebody made a twin-turbine-taildragger tug, you could get the tow
pilots to PAY for that time (building time for th airlines...).
Turbine Beech-18 gets logged as Complex-Multi-Taildragger-Turbine-High
Performance time...worth $200.00 per hour for training to be a line
pilot. Yeah, I'd go back to the club and put up with the politics for
that!

Since AUTO fuel will quickly be over $4.00 per gallon (it already has
"traded" above that in Beverly Hills), the winches aren't going to be
a hell of a lot better -- if we must insist on suckering, er I mean
recruiting teenagers into our dying sport. (Flame away, guys...I'm
trying to get my kids interested -- _I_ have a hard time competing
with video games, even when I shut the power off).

I suspect we'll soon be back to hilltops and bungee cords... Quick,
we must assemble a protest march to SAVE TORREY PINES (Gliderport)!!!!

-Pete
#309
(I just donned my flame retardant suit).

P.S.: For the record, I agree with Bill -- EVERY "club" should have a
winch. And I think winch launches COULD compete with video games.

Actually, a winch launch to 2000agl uses very little fuel. Getting to
the gliderport will use far more.

Frank

Frank Whiteley wrote:

Actually, a winch launch to 2000agl uses very little fuel. Getting to
the gliderport will use far more.

Solar cells charging batteries all week for the electric winch, and ride
your bike to the airport. Save the gas for the retrieves :-)



Shawn

shawn wrote:
Frank Whiteley wrote:

Actually, a winch launch to 2000agl uses very little fuel. Getting to
the gliderport will use far more.

Solar cells charging batteries all week for the electric winch, and ride
your bike to the airport. Save the gas for the retrieves :-)

Nice idea, but the price of solar cells had better drop lots.
Either that of a big win at Vegas is necessary.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

Not could - DO!

We winch only - in vintage rag and tube mostly and we seem to be able to attract
teenagers with our equally old winch.

309 wrote:
On Oct 20, 9:45 am, "Bill Daniels" bildan@comcast-dot-net wrote:
I don't think any tow plane ever pays for itself once all 'hidden' costs are
considered. Operating an old rag and tube airplane of any kind is fraught
with 'nickel & dime' costs that add up. The last time I took a hard look, a
Pawnee runs about $150 USD/hour. With rapidly escalating costs of fuel and
insurance, it will probably be $200/hour by next summer. You don't operate
small airplanes to make money, you do it because you either need to or want
to. Tugs are cost centers not profit centers.

I think any club interested in lowering operating costs should be
investigating winches.

Bill Daniels

I forgot to add my "turbine tow would require winch launch
authorization" punch line. ;-) Thanks, Frank.

If somebody made a twin-turbine-taildragger tug, you could get the tow
pilots to PAY for that time (building time for th airlines...).
Turbine Beech-18 gets logged as Complex-Multi-Taildragger-Turbine-High
Performance time...worth $200.00 per hour for training to be a line
pilot. Yeah, I'd go back to the club and put up with the politics for
that!

Since AUTO fuel will quickly be over $4.00 per gallon (it already has
"traded" above that in Beverly Hills), the winches aren't going to be
a hell of a lot better -- if we must insist on suckering, er I mean
recruiting teenagers into our dying sport. (Flame away, guys...I'm
trying to get my kids interested -- _I_ have a hard time competing
with video games, even when I shut the power off).

I suspect we'll soon be back to hilltops and bungee cords... Quick,
we must assemble a protest march to SAVE TORREY PINES (Gliderport)!!!!

-Pete
#309
(I just donned my flame retardant suit).

P.S.: For the record, I agree with Bill -- EVERY "club" should have a
winch. And I think winch launches COULD compete with video games.

"309" wrote in message
ups.com...
On Oct 20, 9:45 am, "Bill Daniels" bildan@comcast-dot-net wrote:
I don't think any tow plane ever pays for itself once all 'hidden' costs
are
considered. Operating an old rag and tube airplane of any kind is
fraught
with 'nickel & dime' costs that add up. The last time I took a hard
look, a
Pawnee runs about $150 USD/hour. With rapidly escalating costs of fuel
and
insurance, it will probably be $200/hour by next summer. You don't
operate
small airplanes to make money, you do it because you either need to or
want
to. Tugs are cost centers not profit centers.

I think any club interested in lowering operating costs should be
investigating winches.

Bill Daniels

I forgot to add my "turbine tow would require winch launch
authorization" punch line. ;-) Thanks, Frank.

If somebody made a twin-turbine-taildragger tug, you could get the tow
pilots to PAY for that time (building time for th airlines...).
Turbine Beech-18 gets logged as Complex-Multi-Taildragger-Turbine-High
Performance time...worth $200.00 per hour for training to be a line
pilot. Yeah, I'd go back to the club and put up with the politics for
that!

Since AUTO fuel will quickly be over $4.00 per gallon (it already has
"traded" above that in Beverly Hills), the winches aren't going to be
a hell of a lot better -- if we must insist on suckering, er I mean
recruiting teenagers into our dying sport. (Flame away, guys...I'm
trying to get my kids interested -- _I_ have a hard time competing
with video games, even when I shut the power off).

I suspect we'll soon be back to hilltops and bungee cords... Quick,
we must assemble a protest march to SAVE TORREY PINES (Gliderport)!!!!

-Pete
#309
(I just donned my flame retardant suit).

P.S.: For the record, I agree with Bill -- EVERY "club" should have a
winch. And I think winch launches COULD compete with video games.


As frank pointed out, winches comsume very, very little energy. Roughly
1kW/Hr or a liter of diesel which could easily be biodiesel. An electric
winch, if it could be powered from the grid, would comsume less than 10
cents worth of power per launch.

Bill Daniels

On 21 Oct, 01:03, "Bill Daniels" bildan@comcast-dot-net wrote:

As frank pointed out, winches comsume very, very little energy. Roughly
1kW/Hr or a liter of diesel which could easily be biodiesel. An electric
winch, if it could be powered from the grid, would comsume less than 10
cents worth of power per launch.

I'm bored, so thought I'd play with some numbers ...

I've launched ASH-25's to 1,600' on the wire. At 750kg that's a PE
gain of 750kg x 10 N/kg x 500m = 3.75MJ. There's also a PE gain in
half a ton of wire rope going up 250m: 500kg x 10 N/kg x 250m =
1.25MJ. KE is small in comparison, so that's a nice round 5MJ per
launch.

That's 1.4kWh, but allowing for 85% efficiency in the electric motor
you'd need 1.6kWh. Typical domestic prices here are around 12.5p /
kWh, so that's a nice cheap 20p/launch.

The downside is that you need that energy awful fast. 5MJ over 50
seconds is 100 kW (probably what 200bhp diesel winches get to wire
after transmission losses). That gives two problems.

First of all, you need a very hefty supply. On 415V 3-phase AC, and
assuming a 0.85 power factor, that's a line current of 100 kW /
[sqrt(3) x 415 x 0.85] = 163A. That's definitely non-trivial.

Secondly, you wouldn't get the electricity on a domestic tariff.
Industrial contracts take account of peak power as well as energy
used: the club would need a 100kW supply infrastructure despite only
using, on average, a tiny fraction of that capacity. The power company
will want to recoup the cost of the supply, and that will push the
price up considerably.

The logical alternative would be to use a local energy storage
facility: a great big Li-ion battery bank in the winch would help a
lot. With a 20% service factor (one launch every five minutes) the
average power requirement would come down to 20kW. Still too much for
a standard domestic supply, but a 40A 3-phase supply is pretty
standard. The downside there is that the batteries and associated
supply kit would be horribly expensive.

I believe Tost used to offer a (mobile?) electric winch, and I'd be
interested to know what the power supply arrangements were. As far as
I can see they don't do winches of any sort any more.

I'm sure electric winches could work very well, but I think they'd do
best as fixed installations. Are any in use?

Ian

Ian

Check out this site for one answer to your question.

http://www.beepworld.de/members28/onkelmaggus/

Click on the English page.

Bob

Ian wrote:
On 21 Oct, 01:03, "Bill Daniels" bildan@comcast-dot-net wrote:

As frank pointed out, winches comsume very, very little energy. Roughly
1kW/Hr or a liter of diesel which could easily be biodiesel. An electric
winch, if it could be powered from the grid, would comsume less than 10
cents worth of power per launch.

I'm bored, so thought I'd play with some numbers ...

I've launched ASH-25's to 1,600' on the wire. At 750kg that's a PE
gain of 750kg x 10 N/kg x 500m = 3.75MJ. There's also a PE gain in
half a ton of wire rope going up 250m: 500kg x 10 N/kg x 250m =
1.25MJ. KE is small in comparison, so that's a nice round 5MJ per
launch.

That's 1.4kWh, but allowing for 85% efficiency in the electric motor
you'd need 1.6kWh. Typical domestic prices here are around 12.5p /
kWh, so that's a nice cheap 20p/launch.

The downside is that you need that energy awful fast. 5MJ over 50
seconds is 100 kW (probably what 200bhp diesel winches get to wire
after transmission losses). That gives two problems.

First of all, you need a very hefty supply. On 415V 3-phase AC, and
assuming a 0.85 power factor, that's a line current of 100 kW /
[sqrt(3) x 415 x 0.85] = 163A. That's definitely non-trivial.

Secondly, you wouldn't get the electricity on a domestic tariff.
Industrial contracts take account of peak power as well as energy
used: the club would need a 100kW supply infrastructure despite only
using, on average, a tiny fraction of that capacity. The power company
will want to recoup the cost of the supply, and that will push the
price up considerably.

The logical alternative would be to use a local energy storage
facility: a great big Li-ion battery bank in the winch would help a
lot. With a 20% service factor (one launch every five minutes) the
average power requirement would come down to 20kW. Still too much for
a standard domestic supply, but a 40A 3-phase supply is pretty
standard. The downside there is that the batteries and associated
supply kit would be horribly expensive.

I believe Tost used to offer a (mobile?) electric winch, and I'd be
interested to know what the power supply arrangements were. As far as
I can see they don't do winches of any sort any more.

I'm sure electric winches could work very well, but I think they'd do
best as fixed installations. Are any in use?

The German-made ESW-2B Electrostartwinde has a peak output of 220 Kw and
consists largely of a big bank of heavy duty truck-type lead-acid
batteries to buffer the power supply. It claims all day service from a
12-20 Kw power supply.

My club looked into it and came up with a similar launch cost to your
calculation. The killer was the cost of wiring up the various winch
stations on our (triangular) field. 22/04 accounts for virtually all
launches, 34/16 is used with strong N/S winds and 09/27 is used about
twice a year when wind and ground conditions require it. A lower cost
approach would involve using a diesel trailer generator set. With a
generator we could only wire 22/04 and 34 (the winch point for 34 is on
the cable run to the 22 winch station). If other winch stations were
used the winch would be run from the generator.

With the buffering batteries I think a fairly modest generator could do
the job. New 20 kw diesel trailer sets sell at around $14,000 and I see
that eBay has a 10 Kw unit with a "Buy it Now' price set at $1000. OK,
its a bit small, but the price indicates what's available.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |