motorgliders as towplanes

I'm struggling with a similar question, and it relates to rebuilds. I
guess different rebuilds cost very different amounts, and it seem that
a Pawnee rebuild is $35K and a little more. Could it be that a cheaper
to rebuild tow plane could be a better choice?

On Sun, 08 Mar 2009 14:29:37 -0700, brianDG303 wrote:

I'm struggling with a similar question, and it relates to rebuilds. I
guess different rebuilds cost very different amounts, and it seem that a
Pawnee rebuild is $35K and a little more. Could it be that a cheaper to
rebuild tow plane could be a better choice?

Seems to me that you need to total up several factors:
1) The cost of replacing/rebuilding the tow plane
2) The cost of insuring the replacement for the time you'll keep it
3) The total operating cost for the time you'll keep it, i.e. include
both overhauls/part replacement as well as fuel and oil.

Then calculate the total cost per annum of each course of action.


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

On Mar 8, 3:23*pm, Martin Gregorie
wrote:
On Sun, 08 Mar 2009 14:29:37 -0700, brianDG303 wrote:
I'm struggling with a similar question, and it relates to rebuilds. I
guess different rebuilds cost very different amounts, and it seem that a
Pawnee rebuild is $35K and a little more. Could it be that a cheaper to
rebuild tow plane could be a better choice?

Seems to me that you need to total up several factors:
1) The cost of replacing/rebuilding the tow plane
2) The cost of insuring the replacement for the time you'll keep it
3) The total operating cost for the time you'll keep it, i.e. include
* *both overhauls/part replacement as well as fuel and oil.

Then calculate the total cost per annum of each course of action.

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

SO let's make it an even dozen.

Some other things that apply to all choices (including the Pawnee...)

4) who will maintain the tow plane, what experience on type/model do
they have and how many others doing similar things are available to
learn/get help from?
5) Vendor/product risk - a risk factor for chance the vendor will go
out of business or there will be a nasty AD etc. (yes nastier than the
spar mounts on Pawnee, and yes this risk applies to Pawnees etc. as
well)
6) Parts risks/costs - for some models where the vendor is no longer
making them, what is the risk parts won't be available, will be hard
to find or will be expensive to fabricate if at all possible? (And yes
this risk applies to Pawnees etc. as well, but is reduced somewhat by
their wide use)
7) Operational limitations - find out how whatever you are looking at
tows on the days you need to, on the surfaces, at the temperatures and
density altitudes etc. (e.g. more than a few motor gliders have
cooling issues when it gets hot outside).
8) The expected TBO of the engine - I'd be pretty cautious about
assuming anything based on published TBOs - in general and especially
if the motorglider is towing. I'd go talk to real owners who have been
doing something similar. I have a lot less confidence in the engines
in some of these motorgliders doing as well there say compared to a
Lycoming in a Pawnee - but that is just my bias, unconfirmed by
reality either way. Bear in mind that with towing you may be putting a
lot more time on the engine than others so you'll be the canary in the
coal mine.
9) The utility at all of the motorglider as a XC glider/training
glider (you may just maintain it as a tow plane).
10) Insurance costs, pilot experience requirements and other issues. I
have no idea there, but I'd be calling my insurance agent early on in
the process (like now). Especially if some of the desire is to get
glider pilots with a motorglider endorsement towing - I cringe a bit
at that unless those folks have some power experience and/or a lot of
time in the motorglider.
11) Experimental category issues (if it's an experimental motorglider)
in the USA - I'd expect you would run into issues towing with
motorglider with an contest and exhibition certification.
12) You need to know that a tow release system is available or what
one involve/will cost to put through as a 337 only (if the FSDO would
do that?) and what issues that involves. One of the appeals of the tow
setup on many Pawnee's is the retractable tow rope. I'm guessing there
may not be space to install that in many motorgliders.

Anyhow just more brain food.

Darryl

On Mar 8, 1:03*pm, Brad wrote:
I know this has come up before in RAS. But thought I would bring up
the subject again.

For a club looking at long term projections, which at some point will
include either sticking a "new" engine on a Pawnee or getting rid of
it, does it make sense to start evaluating getting a 2 place
motorglider to serve as a tug and also as a touring/training tool?

Can a MG tug pull a loaded 2 place Blanik on a standard day at SL,
from a 1800' grass strip? Or perhaps such a tug could be used to tow
the members single place ships, and the heavier/ 2-place ships stow
behind the clubs remaining pawnee?

We are blessed with 3 towplanes in our club, there are upcoming
factors that will/are causing us to look at several different
scenarios and am wondering if tossing a MG into the mix might be one
such solution.

Brad

Brad,

Assuming we are talking about towing with MG in the US; can you get
insurance to do this?

Ray Lovinggood
Carrboro, NC, USA

On 8 Mar, 17:03, Brad wrote:

Can a MG tug pull a loaded 2 place Blanik on a standard day at SL,
from a 1800' grass strip?

Mendip GC in the UK tows two seaters very successfully witha Rotax
Falke. As Andreas Maurer writes, initial acceleration is a little low
(a little? I damn nearly wet myself as the upwind wall approached) but
the climb feels like anything else.

Ian

On Mar 8, 1:03*pm, Brad wrote:
Can a MG tug pull a loaded 2 place Blanik on a standard day at SL,
from a 1800' grass strip? Or perhaps such a tug could be used to tow
the members single place ships, and the heavier/ 2-place ships stow
behind the clubs remaining pawnee?
Brad

http://www.youtube.com/watch?v=5UYPyNgf4Q4

Lambada motorglider towing
UFM 13 Rotax 912 100hp

On Mar 9, 9:14*am, wrote:
On Mar 8, 1:03*pm, Brad wrote:

Can a MG tug pull a loaded 2 place Blanik on a standard day at SL,
from a 1800' grass strip? Or perhaps such a tug could be used to tow
the members single place ships, and the heavier/ 2-place ships stow
behind the clubs remaining pawnee?
Brad

http://www.youtube.com/watch?v=5UYPyNgf4Q4

Lambada motorglider towing
UFM 13 Rotax 912 100hp

I watched a Lambada tow an LS-3 from Boulder (elev 5300) on a hot day
and it looked about the same as the SSB 180HP Supercub. The LS-3
pilot reported the same. I can't speak to the maintainability of the
Lambada but keep in mind that the Pawnee isn't sterling in that
department either.

I have some experience of aerotowing behind motorgliders, most Motorfalkes
and Grob 109s. They are alright, but struggle a bit with two-seaters.
There have been times when I have beem towed so slowly (about 50knots is a
K13, two-up) that the glider felt as if it was on the point of stalling!
Remember that a glider has to produce more lift when climbing.

I believe that engine cooling is often a problem, and that M/Gs are less
tolerant to the glider getting out of position. At my club we are
expressly forbidden to low tow, or to carry out training exercises such as
'boxing the tow' when M/Gs are being used. Sorry but give me a 235hp
Pawnee (or a winch launch) anytime!

Derek C

At 15:30 09 March 2009, bildan wrote:
On Mar 9, 9:14=A0am, wrote:
On Mar 8, 1:03=A0pm, Brad wrote:

Can a MG tug pull a loaded 2 place Blanik on a standard day at SL,
from a 1800' grass strip? Or perhaps such a tug could be used to
tow
the members single place ships, and the heavier/ 2-place ships stow
behind the clubs remaining pawnee?
Brad

http://www.youtube.com/watch?v=3D5UYPyNgf4Q4

Lambada motorglider towing
UFM 13 Rotax 912 100hp

I watched a Lambada tow an LS-3 from Boulder (elev 5300) on a hot day
and it looked about the same as the SSB 180HP Supercub. The LS-3
pilot reported the same. I can't speak to the maintainability of the
Lambada but keep in mind that the Pawnee isn't sterling in that
department either.

I observed a 100HP Lambada equipped with 13m wings being used as a
towplane in the 2000 Worlds in South Africa. It seemed to perform
very well despite the moderate density altitude. They were launching
from an asphalt runway and the ground acceleration was slower than
most other towplanes, but once airborne no difference was notable.

The Lambada and similar modern motorgliders are very light (300kg) -
nearly half the weight of the older designs, such as the Grob 109 -
and perform very well.

I have flown a Grob 109 and it had enough trouble getting itself into
the air. The Lambada also handles a lot better than the older heavy
beasts and is a joy to fly.

Mike

On Mar 10, 9:56*am, Mike the Strike wrote:
I observed a 100HP Lambada equipped with 13m wings being used as a
towplane in the 2000 Worlds in South Africa. *It seemed to perform
very well despite the moderate density altitude. *They were launching
from an asphalt runway and the ground acceleration was slower than
most other towplanes, but once airborne no difference was notable.

The Lambada and similar modern motorgliders are very light (300kg) -
nearly half the weight of the older designs, such as the Grob 109 -
and perform very well.

I have flown a Grob 109 and it had enough trouble getting itself into
the air. *The Lambada also handles a lot better than the older heavy
beasts and is a joy to fly.

Mike

What the Lambada's towing performance at less than 1320 pounds gross
suggests to me is that the US Sport Light Aircraft regulations offer
the possibility of a formidable tug.

The Lambada's aerodynamics are great but 80 - 100 HP is inadequate for
heavy 2-seaters and ballasted singles. 135Hp or so combined with a
propeller optimized for max thrust below 60 knots would make a huge
difference. Aerodynamics doesn't count for much below takeoff speed -
there it's all weight, engine and propeller.