best self-launcher propulsion system?

I am curious what group members with experience with self-launchers
regard as the best propulsion system (currently) in terms of in-flight
restart reliability, maintenance, safety, and other operational
factors (e.g., vibration). Of course the electric Antares might win
on all counts except for range, but it is out of my price league.

thanks,

Key

Well, if the Euro keeps declining perhaps you
can afford an Antares (~1.27 today).
The range is more than you might expect,
as you don't need to climb as high before
shutdown as other machines, leaving bigger
reserve (subject to lift convenient to launch).
Good luck,
Best Regards, Dave "YO electric"

PS: My Antares has never failed to air-start
(unlike my previous machine). ~12 seconds
from gliding to power with no fuss.

On Jan 10, 5:21*pm, Dave Nadler wrote:
Well, if the Euro keeps declining perhaps you
can afford an Antares (~1.27 today).
The range is more than you might expect,
as you don't need to climb as high before
shutdown as other machines, leaving bigger
reserve (subject to lift convenient to launch).
Good luck,
Best Regards, Dave "YO electric"

PS: My Antares has never failed to air-start
(unlike my previous machine). ~12 seconds
from gliding to power with no fuss.

Don't need to climb as high?? because?
Engine stows quicker reducing time of drag exposure?
No need to keep the bay doors open for engine cooling reducing drag
exposure?

Please explain.

T

On Tuesday, January 10, 2012 9:09:57 PM UTC-5, T wrote:
Please explain.

Sure, many reasons:

BACKGROUND: All your planning flying any pylon-powered
toy must be around worst case: engine stuck out and not
running. Depending on the model, this can mean very
high sink rates, and badly degraded handling from
wake of pylon and radiator on tail.

The "motor out and not running" MOANR configuration
must be used to plan safety of take-off strip,
departure pattern, distance from airport, air-start
altitude and placement margins, etc.

Antares low-shutdown advantages:
- low sink rate and normal handling with MOANR
- only one control in cockpit to extend/retract
(unlike some which have VERY high workloads)
- normal handling under power makes it easy to
find and center first thermal
- no required cool-down cycle prior retraction
- ~10 second re-extension to power if I don't
climb after shutdown

All the above mean I can concentrate on finding
and centering the first thermal rather than
"engine management", with low stress. My average
shutdown is ~1000 feet, in locations where there
is lift near the launch and not too much traffic
(ie, Sterling, Hobbs, Uvalde). This leaves a very
substantial reserve for self-retrieve, though
this is certainly not a power XC cruiser.

Hope that helps !
Best Regards, Dave "YO electric"

PS: Someone needs to come up with a really good
and appropriately foul acronym for "motor out and
not running".
Boggs, you're on...

Hi Gang
I have had a DG800B and a Stemme S10VT for many years and currently
have a Phoenix so I have some experience with self launchers. I almost
purchased an Antares a couple of years ago but discovered a gotcha
that for me was a show stopper. And that gotcha? Lithium batteries
cannot exceed fairly modest temperatures before they have to be
shutdown meaning if I left an Antares in the hot midday sun in Nevada
for a couple of hours I might not even be able to reach 1,000 feet
before the electric system would automatically shut down. This might
be OK in cooler climates but not at Minden.
The vibration problems of the DG require almost constant monitoring
of the engine and its supports for wear and tear. The Wankel engine of
the 26 is apparently much less prone to vibration problems. Anything
using the Rotax engine is reliable. The Stemme had maintenance
problems but the Rotax 914 engine was reliable.
So if you want the highest performance single place self launcher I
would recommend the Ventus or the 26. For a 2 place self launcher the
Stemme is hard to beat with its much better ground handling compared
to a 25 although the performance of the 25 is a little better.
For a little old guy like me who has completed all the 6 hour XC
flights he ever wants to do in the DG800B and the Stemme you might
want to consider a touring motorgllider and there is one that clearly
stands above the rest and that is the Phoenix. It is the first that
allows the outer wing panels to be removed in less than a minute
reducing the wing span from 15 meters to 11 meters thereby allowing
the Phoenix to be parked in a regular hanger. In the short wing
configuration it is a superb LSA power plane and in the long wing
configuration it is a medium performance motorglider. It is registered
as a LSA glider even though in the short wing configuration it is
clearly a standard LSA power plane. The FAA had never considered this
a possibility and a registered aircraft cannot have 2 certifications.
That suits me.
Dave

On Wednesday, January 11, 2012 1:24:33 PM UTC-5, kd6veb wrote:
... I almost
purchased an Antares a couple of years ago but discovered a gotcha
that for me was a show stopper. And that gotcha? Lithium batteries
cannot exceed fairly modest temperatures before they have to be
shutdown meaning if I left an Antares in the hot midday sun in Nevada
for a couple of hours I might not even be able to reach 1,000 feet
before the electric system would automatically shut down. This might
be OK in cooler climates but not at Minden.

Huh ?

I regularly self-launch at Uvalde, Hobbs, etc.
Not exactly locations I need the Sorel boots.

Battery heating is the third power of current.
Thus, reducing from max power shortly after
take-off reduces heating enough that this has
never been an issue for me in actual operation
over many seasons (including multiple contests
at Hobbs and Uvalde, launching on HOT days with
full water ballast).

Hope that's clear !
Best Regards, Dave "YO electric"

PS: Someone needs to come up with a really good
and appropriately foul acronym for "motor out and
not running".
Boggs, you're on...

PUNT?
Pylon Up Not Turning

PULP
Pylon up Lost Power

PENIS
Pylon Extended No Ignition... ****

???
Boggs

Pylon Up Nothing Turning?

PENIS
Pylon Extended No Ignition... ****

???
Boggs

DINGDINGDING WE HAVE A WINNER!

A 2-stroke is a 2-stroke is a 2-stroke.

I own one outright, have a share in another, have looked closely at many
others and quizzed many other owners. If you're a fellow-member of the
self-launch owners club they'll talk honestly because they think you
won't rat on them - one day you'll have to sell one too. All of the
engines, as engines, are about equally reliable. The problem with all
of them is that a 2-stroke continually tries to vibrate everything
attached to it to death. Fuel line joiners, electrical wiring,
thermocouples, temperature transmitters, starters, flywheels,
alternators, magnetos, ignition boxes, fuel pumps, carburettors, drive
trains, radiator mountings, cooling hoses, EVERYTHING - including the
aircraft.

The reliability of the engine itself is not the problem. What brings
the system undone is the vibration induced failure of essential
accessories and other components. Straight, simple engine failures do
occur but a vibration induced failure somewhere else in the chain is
much more likely to leave you in trouble - and it will do so quite
often. Won't extend, won't start, won't retract, broken drive belt, are
all just as much engine failures as a broken crankshaft and much more
common.

I'm afraid that's the dirty, little secret all of us self-launcher
owners keep to ourselves.

Of course except for Schleicher's Wankel. Mind you, when the Wankel
does go you need to have a lot of money saved up. Your local A&P will
be even more reluctant touch it than he is with a 2-stroke so you'll
have to put it in a box and post it to Poppenhausen. That's why Rotax
and Solo still find a home.

Safety - They're all safe if you keep your hand and head out of the prop.

Maintenance - never take your eyes off the wiring, the fuel lines, the
brackets, the flanges, the hose clips, the staked bolts, etc.
Accessible - none of them are accessible within the normal range of
human limb mobility. DON'T buy one that needs to have its fuel lines
changed regularly!

Don't get me started on the engineering quality that demands stainless
braided, aircraft quality fuel lines - joined by NYLON barbed fittings!

And for a normal single-seater, anything less than about 45-50HP is a
sustainer, not a self-launcher, no matter what it says on the box.

GC

On 11/01/2012 11:48, key wrote:
I am curious what group members with experience with self-launchers
regard as the best propulsion system (currently) in terms of in-flight
restart reliability, maintenance, safety, and other operational
factors (e.g., vibration). Of course the electric Antares might win
on all counts except for range, but it is out of my price league.

thanks,

Key