Motorglider Tug

BTIZ wrote:
want to be doing that in a 100hp tug

Theoretically, with 100hp you can obtain 10m/s climb rate with a 750kg
glider (about 5 kts or 2000ft/min). It's all a question of
efficiency (both glider and tug)...

Cheers
-Gerhard
--
Gerhard Wesp o o Tel.: +41 (0) 43 5347636
Bachtobelstrasse 56 | http://www.cosy.sbg.ac.at/~gwesp/
CH-8045 Zuerich \_/ See homepage for email address!

BTIZ wrote:

650M in elevation is approximately 1800-2000ft?
take that up to 3000ft or more on a 45C day..

The 115hp version of the Dimona is turbo charged, so density altitude
isn't an issue.

now add some down draft
(sink) or rotor

This is a bad tug pilot who tugs through sink. And rotor... well, on the
downdraft side, you'll always go down with something less than a rocket,
I guess. On the updraft side, though...

Stefan

----------
Dans l'article GKDkd.92846$bk1.22713@fed1read05, "BTIZ"
a écrit :


Most motor gliders of the "Katana Extreme" variety do not have enough
"oomph" (HPower) to get a regular glider into the air. You may find that
some have done duty to tow ultralights aloft. Check out the USHGA web pages.

Most motorgliders (older types) do not have enough HP to get them selves
into the air on hot high days here in the mid-west. Although I do understand
that the DG808B does very well, but the Grob109 is very anemic. I've read
reports that the older DG400 was "doable" at a very poor climb rate.

BT

"Ray Lovinggood" wrote in message
...
Who is using a motorglider as a tug? Please send details!

Your location. Country. Field surface, length, elevation,
temperatures.

What type of tug?

What gliders towed?

Good, bad, and ugly of using the motorglider.

Who insures? Costello, here in America, will not insure
a motorglider for towing.

Thanks,
Ray Lovinggood
Carrboro, North Carolina, USA





My club uses since several years a Super Dimona with a 115 hp turbo charged
engine. We tow all gliders with it, including an ASH25 turbo (engine
unmounted) and a Nimbus 3 which is always ballasted, although sometimes only
lightly. Only when the waiting line becomes long, we also use our second
tug, a Rallye with 180 HP. Towing times are similar with both tugs, not cost
of course, hence the exceptionnal use of the Rallye, since the pilot anyway
pays the same for both.

Good things: nearly same performance as the Rallye for a lower cost. May be
used as a motorglider for itself when not towing, although this is very
rare. May be flown with just a glider licence, although not for towing.
No corrosion problems unlike the Rallye. Lower noise than most conventional
tow planes, this helped to buy it as there are public subventions for the
reductions of noise. Airbrakes, partial water cooling and closable air
cooling intakes help fast descent for minimizing tow time.

Bad things: the reliability of the engine is lower than expected. Maybe our
plane is an exception, but we had a lot of minor and major engine failures,
including a crack in the main engine body, which implied replacement of the
engine. Full power with maximum turbo pressure is limited to 5 minutes, this
doesn't hurt as most tows are shorter than that.

Runway 1000m, altitude 370 ft, temperature 20-35°C, reached 40°C in August
2003. Prevailing winds are crosswinds.

Robert,

If your club had to buy a towplane all over again,
would you still buy the motorglider, or would you get
another Rallye or other 'normal' airplane?

Thanks,
Ray Lovinggood

Bad things: the reliability of the engine is lower
than expected. Maybe our
plane is an exception, but we had a lot of minor and
major engine failures,
including a crack in the main engine body, which implied
replacement of the
engine. Full power with maximum turbo pressure is limited
to 5 minutes, this
doesn't hurt as most tows are shorter than that.

Runway 1000m, altitude 370 ft, temperature 20-35°C,
reached 40°C in August
2003. Prevailing winds are crosswinds.

Robert,

If your club had to buy a towplane all over again,
would you still buy the motorglider, or would you get
another Rallye or other 'normal' airplane?

Thanks,
Ray Lovinggood

Bad things: the reliability of the engine is lower
than expected. Maybe our
plane is an exception, but we had a lot of minor and
major engine failures,
including a crack in the main engine body, which implied
replacement of the
engine. Full power with maximum turbo pressure is limited
to 5 minutes, this
doesn't hurt as most tows are shorter than that.

Runway 1000m, altitude 370 ft, temperature 20-35°C,
reached 40°C in August
2003. Prevailing winds are crosswinds.

we don't tow through sink or rotor intentionally.. and for the local area we
know where to predict the rotor... but as for sink.. what goes up must come
down eventually.. and there is sink, to get back into the lift... can't
always fly on tow in thermal lift.. when the cores are narrow and strong..

BT

"Stefan" wrote in message
...
BTIZ wrote:

650M in elevation is approximately 1800-2000ft?
take that up to 3000ft or more on a 45C day..

The 115hp version of the Dimona is turbo charged, so density altitude
isn't an issue.

now add some down draft (sink) or rotor

This is a bad tug pilot who tugs through sink. And rotor... well, on the
downdraft side, you'll always go down with something less than a rocket, I
guess. On the updraft side, though...

Stefan

BTIZ wrote:

we don't tow through sink or rotor intentionally.. and for the local area we
know where to predict the rotor... but as for sink.. what goes up must come
down eventually.. and there is sink, to get back into the lift... can't
always fly on tow in thermal lift.. when the cores are narrow and strong..

.... then you pull the release knob.

Stefan

Robert,

If your club had to buy a towplane all over again,
would you still buy the motorglider, or would you get
another Rallye or other 'normal' airplane?

Thanks,
Ray Lovinggood

Bad things: the reliability of the engine is lower
than expected. Maybe our
plane is an exception, but we had a lot of minor and
major engine failures,
including a crack in the main engine body, which implied
replacement of the
engine. Full power with maximum turbo pressure is limited
to 5 minutes, this
doesn't hurt as most tows are shorter than that.

Runway 1000m, altitude 370 ft, temperature 20-35°C,
reached 40°C in August
2003. Prevailing winds are crosswinds.

... then you pull the release knob.

Stefan

tell that to a student learning to fly on tow..

----------
Dans l'article , Ray Lovinggood
a écrit :


Robert,

If your club had to buy a towplane all over again,
would you still buy the motorglider, or would you get
another Rallye or other 'normal' airplane?


I think it would be another motorglider. The case in some way already
happened, as during some time when the Rallye was grounded for corrosion and
the Dimona was unreliable/unavailable, the club hired another Dimona. This
is based on the assumption that most of the problems we had with the engine
are exceptionnal and would not happen with another one. One factor to be
considered is also what kind of fuel is used. The Dimona may use Avgas 100LL
as well as unleaded 95 automotive gas. The second one is recommended for
better reliablity, as the lead in the 100 LL alway causes more or less
contamination of the oil which is the same as the oil used for actuating the
variable pitch system, and we had problems probably due to that. But as we
need 100 LL for the Rallye and have only one tank, we are stuck to that as
long as the Rallye remains. The cost for splitting the tank was evaluated
and considered prohibitive regarding the expected life of the Rallye. If
some day it is replaced by another Dimona, we would be able to switch to
unleaded 95. Anyway another Rallye is probably out of question since
manufacturing of them stopped a long time ago, only old ones are available
and buying one of them is certainly buying a lot of problems. E.g. when the
Rallye was grounded for corrosion, several monthes were spent just waiting
for the answer of the manufacturer for the proper repair procedure without
which no work could be legally started.