At 08:40 AM 2/10/2010, you wrote:
Or try a 172 with 200-210hp engine conversion.
More expensive but 4 seats for utility as private transport.Or
simply a 182 or Citabria/Scout.
In Szeged we had Dynamic ultralights as well - seemed OK.
The Question I asked "why" a motorglider was not really answered, if
it MUST be a motorglider then OK, but there are lots of better tug options.
Tom
-
Some more random thoughts from a private exchange :
Those prices are ASKING prices. Likely you could do a fair bit better
right now. You really want one with an "on condition" engine that is
over TBO and an airframe with no corrosion.
Don't need any fancy instruments either. You'd remove them and the
passenger seat when not required.
A very experienced LAME I know hates Pawnees for being high
maintenance and thinks C150s are really tough aircraft. A 6000 hour
C150 isn't high time. Unlike the Blanik the C150 has a fatigue life
in the 20,000 hours plus range according to another LAME.
How many hours a year do the tugs fly?
---
I doubt that glider towing will stand the $250,000 +cost of new GA
airframes and I can't actually think of too many that would be good
towplanes (too much fancy equipment, furnishings etc).
Eddie Madden is using a 100HP Eurofox at Tocumwal and it tows. Another option?
Towing gliders is probably a honourable old age for old semi retired
airframes that are fully depreciated. Like aerial fire fighting in
the USA. They use old aircraft, not new ones. The trick is to find
the old types that have fewest structural problems. I realise that
the C150 and C172 weren't designed for fatigue lives. They were
designed to the old CAR 3 not FAR 23 standard. However, with multiple
tens of thousands of airframes flying for 65 years with minimal
structural failures (I've heard, none) when flown within the envelope
(the C150 and C172 are descended from the C120 and 140 of the 1945
-1950 era) you'd have to say that was good enough. I can't give you
the reference but even though these aircraft weren't fatigue
justified I have heard that this has been looked at by engineers
since and the numbers were such that the aircraft were considered to
be unlikely ever to reach those hours. Dave Thurston has some
opinions on this in his books.
BTW all single engined Cessnas were allegedly designed and stressed
for glider towing, including the C150 (source an old Soaring
magazine) - what were they thinking? Maybe in Alaska, on a cold day,
with a small light glider. Most 100HP C150's have enough trouble
climbing on their own. Otherwise quite delightful aircraft.
There's also the option of an LSA . Somebody is doing a Super Cub
clone with 180HP Lycoming. Meets the LSA 120 Knot straight and level
limit with a cockpit placard that says "reduce power in order not to
exceed 120 knots in level flight".
A long wing option BD-4 kit with O-360 and minimal equipment is
another option. About the same weight as a C150-180. Very useful as
a power plane when not towing. Homebuilt experimental lets you fit
good things like two electronic ignitions. Had a look at the
potential shrapnel on a impulse coupling magneto? I did and bought a
second LSE ignition.
Is towing any worse for an airframe than circuit bashing with
students? The tug pilots usually get pretty good at doing good landings.
So how many hours a year do the tugs fly?
-----
I got a reply from an ASC member on that:
Due to the few hours left on one, the club have been heavily
favouring one over the other, so one does 200+ and the other does
between 50-100.
Well you do need a launch means. One tug is acceptable if you have a
good LAME on call to keep it flying and/or a casual replacement that
you can hire quickly. Otherwise you become a social club with some
interesting capital equipment in the shed.
At say 300 hours a year flying a 5000 or 6000 hour airframe that will
go to at least 15000 hours should last 30+ years. I think we should
leave the provision of launch means then to those who may need them
then, if indeed anyone needs them at all.
As for tyres, hoses, upholstery, you don't need upholstery in a tug
(it ought to look like a WW2 aircraft inside) and the hoses are
calender life limited anyway and tyres, wheels, brake pads along with
engines and propellers are "wear out" items which routinely need
replacing anyway. Get a good old airframe, inspect and repair as
necessary during the larger engine conversion and it would be a
little precious to start worrying about structural failures on such
well proven airframes as the C150/C172. As Jim said you can get 180HP
172s also. The earlier ones were lighter and do make good tugs. I've
had a couple of launches behind one which had no paint and the rego
was in black electrical tape. Went well as did the 195HP Cessna Hawk
XP with the Contintental O-360 6 cylinder engine.
I do have some reservations about the lightly built ultralights for
long term durability in towing service and they are likely to cost
around twice what you can put a refurbished C150-180 in service for.
Which sort of shows that maybe the club really only needs one tug
afterall. But there are too many glider pilots who don't accept
that ASC is a much smaller club than it used to be.
Well it would be disappointing to think that 30 years of concentrated
effort and thought by the GFA and ASC towards that goal wouldn't pay off.
Mike
Borgelt Instruments - manufacturers of quality soaring instruments since 1978
phone Int'l + 61 746 355784
fax Int'l + 61 746 358796
cellphone Int'l + 61 428 355784
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