Uncle Fuzzies take on Self Launchers

At 00:34 23 August 2013, Eric Greenwell wrote:
Andrew wrote, On 8/22/2013 9:10 AM:

Talking about motor gliders with extending masts and gas
engines: all the advantages seem (at least partially) offset by
corresponding disadvantages, either physical or psychological.
For
example, the major convenience of not needing a towplane is
partially offset by the usually-greater difficulty and risk of self
launching.

That is a curious statement. All the motorglider pilots I know
think
self-launching is easier than towing:

- you can taxi to the runway instead of pushing the glider there
- the steerable tail wheel means you go where you want to
instead of
being ballistic during the start of the takeoff roll, and even cross
winds are more easily handled
- no dropped or mishandled wings due to the wing runner,
because you
start with a wing tip on the ground, and raise it when you have
aerodynamic control
- it's easier to fly by yourself instead of following a towplane,
especially in turbulent conditions, and you get to go exactly
where you
want to

When it comes to cross-country flying, a large fraction
(99%?) of field landings are eliminated with a motor glider, but
the
"worry element" always remains (motors don't always start,
and a
field landing in a motor glider will be more difficult and risky).
Overall,
my experience is that I prefer my motor glider, however
the advantages are not as great as I had imagined.

If you haven't read my free "Guide to Self-launching Sailplanes"
(56
pages), now would be a good time:

https://sites.google.com/site/motorg...tions/download
-the-guide-1

There should be no more "worry element" than flying an
unpowered glider.
As fellow motorglider put it: "Plan A is to land in that
field/airport;
Plan B is the motor starts and I get to go back to soaring.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us"
to
email me)
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS,
Flarm
http://tinyurl.com/yb3xywl



Hi Eric,

thanks for your comments. I have read your Self-Launching
Guidebook many times, and it's invaluable. I'll add my brief
comments here towards the points in your message:

1. My experience with my steerable tailwheel is that its a great
help at low power settings, taxying out and getting aligned on the
runway, but once the tailwheel gets light on the grass, as it always
does with full power, I am back to rudder control of heading, and
it takes a LOT of rudder in a XW to provide as good a directional
control as the pull from a towrope. Maybe it would be better on
tarmac, I don't know. My MG manual quotes a demonstrated XW
of 11kts.

2. Compared to aerotows, the ease of the stick-and-rudder part of
self-launching is clearly little different, but self launching is more
difficult in that it requires the MG pilot to additionally perform
engine monitoring, management, shutdown. I also use a right-
turnout as soon as possible, to remain close to the airport while
low. Regarding launch risk, I suspect engine failure is more likely
in a MG, and faster reactions would be needed in the event of a
low-level power loss.

3. About the 'worry' of field landings. As you say, there are
completely logical procedures for staying safe in a MG if a field
landing becomes imminent. However I also think it would be very
easy to fail to get an extending-mast gas engine up and running,
and the unknown risks of any field landing always worry me. The
result, for me, is that my MG does not produce the worry-free XC
flying I had imagined it would.

Overall, I do prefer my MG to a pure glider, mostly because of the
freedom from scheduling or waiting for an aerotow. That's a pure
advantage that I get every flight, and is very enjoyable.

regards
andrew