One of my original questions was since both these designs are over 12
years old (normal life span for a design) what changes would you like
to see in future designs? And when do you expect a new self launch
motor glider design to come on the market?


On Oct 28, 11:11 am, "bumper" wrote:
"Gary Evans" wrote in ...



A couple of DG800 advantages that bumper overlooked.

1) An engine that doesn't cost $17000 to replace.
2) An engine that can be worked on with out having
to remove it from the fuselage. While this may not
seem like something you will ever have to do you'll
want to keep a couple of big friends around for spark
plugs changes. I believe there were at least three
engines pulled for one problem or another at this years
ASA Parowan camp. They also had their own cart to haul
the engines around for repairs but I'm not sure if
thats a standard 26 option.
3) A superior engine management system (DEI) with manual
back up.

IMO the engine related issues sum up the big difference
between these two ships as performance both in glide
and under power are way similar. The 26 has a smoother
engine and the 800 has one, which is easier and cheaper
to maintain. They are both state of the art ships and
you won't be sorry for buying either.
DG has done a pretty fair comparison between the 26/800/Ventus
2cM that can be viewed here -
http://tinyurl.com/yz4shsGary,

I agree that performance wise they're essentially equal. On your other
points:

1) The 17K figure may seem a lot, however, the need to completely replace
one of these engines is quite rare. Replacing the Wankel's major engine
parts costs around $8K Euro. Those few cases were this was necessary were
most likely due to oil starvation and a Chernobyl type melt down. You do
need to keep oil in the tank and pay attention to engine temperatures.

Otherwise the Wankel, besides having small size which allows a narrow
fuselage, has excellent power density and vibration free smoothness. The
Wankel is also remarkably reliable and trouble free. The lack of vibration
means that stuff doesn't crack, break or fall off the motor and things
nearby - - a major positive attribute as compared to most 2-strokes.

I heard that two of the 26E engines pulled at Parowan where to replace
broken drive belts. This is an unusual occurrence, as the Wankel, with it's
multiple smaller power pulses per revolution, is gentle to the drive train
as compared to a 2-stroke. There was talk of a change in formulation used in
manufacturing the Gates Poly-Chain drive belts. AFAIK, the reason for this
breakage hasn't been 100% resolved/confirmed. I do know that some owners
have 150 hours and more with no drive belt issues. For the whole 26E fleet,
I'm aware of only the Parowan failures and one prior failure caused by a
bearing failure in one of the guide pulleys. Belt failures have occurred on
the 2-stroke powered ships as well, a backfire on start up will do the deed.

2) Yup, on my 26E the engine must be pulled to change plugs. There is a
factory mod that provides an access hole to allow plug service without
pulling the engine. It's retrofitable to my ship, but since I've never had
to service the plugs, I don't plan on adding this mod. Besides, the engine
package is easy enough to remove and can be done solo in about an hour
(maybe half that with good help). Remove 3 bolts, 3 wiring cable plugs, a
couple of Bowden cable connections (throttle and prop stop) and a fuel line.
A "cherry picker" engine hoist is needed if removing the engine solo. I've
only done this once in the 4 years and 23 engine hours I've had the ship,
but plan on doing it for the next annual just to look at things.

3) When shopping, I considered DG's DEI engine control a plus, but after
using the simple ILEC engine control, as used on the 26E and many other
self-launch gliders, I'm not so sure. To put away the prop on the 26E:

a- turn off ignition

b- when prop stops, engage manual prop-stop lever (this swings a rubber
stopper into the prop arc) and nose over slightly to windmill prop into stop
as viewed in rear view mirror.

c- push pylon switch down until prop just disappears from view in mirror
(this is the cool down position), at thermalling speeds, the additional drag
caused by the partially extended prop/radiator is minimal and still allows
reasonable climb performance.

d- In my ship, the cool down period takes 3 - 4 minutes. After observing a 2
C drop in engine coolant temp, push switch to retract prop fully.

Simple, reliable, almost no maintenance required . . . even a cave man
could do it. A DEI? Kind of like the automatic parking option on the new
Lexus - - why bother? (g)

I agree the most prominent mechanical difference between these two ships is
the power train. I do not agree that the DG's 2-stroke engine is easier and
cheaper to maintain. Given, replacing a 2-stroke engine is much less
expensive than replacing the Wankel. However, this needs to be tempered by
the fact that the Wankel will hardly need replacement if operated with
reasonable care and its on-going maintenance is usually less expensive.

After talking to Tom and Billy Stowers (High Country Soaring, and who have
worked on all manner of these ships), my impression is that the 2-stroke
maintenance issues they experience is an order of magnitude greater with
2-strokes than on the Wankel powered ships. This is also borne out by a
check of the relevant AD's. The ASH26E has but two airworthiness directives
(rotor cooling fan and muffler), both early-on teething problems that were
resolved years ago.

The many more subtle differences between the two ships are perhaps more
subjective. I talked with Larry Mansberger about the "beneath the skin"
differences between DG and Schleicher as I was not in a position to take a
chain saw and see for myself. Keeping in mind that this was several years
ago and the wing sections I saw were made prior to current DG factory
ownership, the innards of the Schleicher wing looked to be assembled with
the same care and attention to detail as the outer parts the customer
normally sees - - not so inside the DG wing.

Many of the DG's at Minden have gel-coat surface cracks on the wings,
commonly around the spoiler boxes. I haven't seen this on Schleichers,
though some earlier 26E's did show the wing spar profile after several
years - - later versions, my 2002 model included, have not done this - so
far. Subjectively, the 26E cockpit finish is nicer and ergonomics, even for
taller pilots, is excellent. The DG's pigeon-toed rudder pedals, when I was
trying it on, gave me foot cramps.

I've asked several DG800 series owners, on the Minden ramp, why they chose
the DG-800 series over the ASH26E. At the time, purchase cost was
essentially the same for either ship and probably is still close. By a large
margin the answer was availability, the delivery wait for the 26E then being
two years, more than double that for the DG at the time. For one DG owner,
the 800's two piece wing was a deciding factor (the 26E's one piece wing
means the trailer must be longer, at about 35").

All that said, owners of both these ships seem happy with their decisions,
and that's what really counts. My strong bias in favor of the ASH26E may
well be indicative of a underlying personality flaw (g), I have little
tolerance for things mechanical that could have, or should have, been done
better.

bumper