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#21
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To Pawnee or not to Pawnee...that is the question...
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. |
#22
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To Pawnee or not to Pawnee...that is the question...
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 |
#23
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To Pawnee or not to Pawnee...that is the question...
"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 |
#24
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To Pawnee or not to Pawnee...that is the question...
Bill Daniels wrote:
I don't think any tow plane ever pays for itself once all 'hidden' costs are considered. A club which wants to survive *must* charge tows at full cost. At my club, the tow plane *does* pay for itself. Which means that tows aren't exactly cheap. |
#25
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To Pawnee or not to Pawnee...that is the question...
"John Smith" wrote in message ... Bill Daniels wrote: I don't think any tow plane ever pays for itself once all 'hidden' costs are considered. A club which wants to survive *must* charge tows at full cost. At my club, the tow plane *does* pay for itself. Which means that tows aren't exactly cheap. "Not exactly cheap" tows leads to an activity called "assembly practice". This is where a pilot drives to the gliderport, assembles his glider but then decides the conditions aren't worth the cost of a tow so he de-rigs without flying. When you see "assembly practice" or pilots driving to the gliderport without flying, it's a sign your aero tow operation is verging on an economic death spiral. You'll reach a point where tow costs are so high that you can't do enough tows to pay the fixed overhead which, in turn, requires still further increases in tow costs. At $5 - $10 for a winch launch, you'll never see "assembly practice". At $15/launch, a winch can not only support itself, it can support that tug and some nice glub gliders. Even if you will never take a winch launch, get one anyway just for the revenue stream. Bill Daniels |
#26
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To Pawnee or not to Pawnee...that is the question...
Frank Whiteley wrote:
Not positive, but I don't think multiple glider tows are allowed under the SSA insurance plan. The SSA insurance plan isn't the only one available. Double tows to the mountains are pretty routinely used at Williams Soaring Center in California... Marc |
#27
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A club which wants to survive *must* charge tows at full cost. At my club, the tow plane *does* pay for itself. Which means that tows aren't exactly cheap.[/quote] How much? and, what is the breakdown, for instance, 2000' agl, + per minute or + per 100' ? does the tow charge cover all the a/c costs, like insurance, maintenance, replacement after time etc? curios bagger |
#28
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To Pawnee or not to Pawnee...that is the question...
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 |
#29
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To Pawnee or not to Pawnee...that is the question...
On 16 Oct, 13:54, Martin Gregorie wrote:
Dan G wrote: Why is it only old Pawnee vs. new Husky? Are there not used efficient 180hp tugs available in the US? I was up at Milfield with my Libelle a week ago, where they run three tow planes: 150 Pawnee, 180 Supercub, 235 Pawnee. I couldn't see much difference between the Supercub and the 235 Pawnee but the 150 Pawnee had a much slower climb rate than either of the others: more like my club's 160hp Rallye. It's actually a 160hp Pawnee - it was uprated a few years back. Although there have been 150bhp - 180bhp conversion in the US, 160bhp (it's a helicopter engine) was as far as the CAA would allow without a complete new set of stress calculations. When the wee Pawnee arrived it had a four blade prop and a good silencer: amazingly silent but couldn't pull the skin off a rice pudding. I remember circling overhead in weak wave for some time before landing once, waiting for it to get a Bocian off. Three circuits of the airfield, got to 350', gave up. Ian |
#30
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To Pawnee or not to Pawnee...that is the question...
Bill Daniels schrieb:
"Not exactly cheap" tows leads to an activity called "assembly practice". I've never seen this. The glider pilots I know want to fly, that's why they are glider pilots, after all. When you see "assembly practice" or pilots driving to the gliderport without flying, it's a sign your aero tow operation is verging on an economic death spiral. If you operate tow planes that don't pay for themselves, then your aero tow operation is certainly verging on an economic death spiral. At $5 - $10 for a winch launch, you'll never see "assembly practice". Unfortunately, there are airfields from wich you can't reach thermals from the winch. Or, if you reach them, you do so only three ours later than with aerotow, which makes big flights impossible. I *know* there are pilots lucky enough to operate from airfileds where you reach your first thermal reliably from the winch at 10 a.m. I just don't happen to operate from such a field. |
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