Andor, since you no longer offer the 18m tips for the 20E, it would seem
there is no reason to keep the junction between the inner and outer wing
panels out toward the tip. Have you considered moving the junction
further inboard so the glider will fit in a shorter trailer?


Andor Holtsmark wrote:
At 21:54 03 June 2006, Eric Greenwell wrote:
I'm wondering how you know the designers' view - did
the designers tell
you directly?

-I happen to be employed as an engineer at a small
company named Lange Flugzeugbau. I did not work there
when the decision was made to go electric, but in my
view it was a correct decision. Please note that what
I write here are my personal opinions, which should
not in any way be mistaken with the official view of
Lange Flugzeugbau.

In any case, I don't think it's the self-launcher that

sets the requirements, but really the customer. As
you know, there are
many pilots that prefer the gasoline engine self-launcher
because it is
much lighter and has a much greater range.

-Self launching is a task. An aircraft is a system
optimized for one or more tasks. Self launching is
a way to get airborne and reach thermaling altitude
easily and with a minimum of hazzle. The 20E performs
this task beautifully. How often do you need 3000 m
climb altitude to enter your first thermal? In my experience,
500-800 m should be enough. This should in most cases
leave you with quite a bit of energy to get home with,
or at least to the nearest airfield.. or if you really
have messed things up, to a landable area. It should
here be noted that if you happen to be high, then an
electrical propulsion system is superior to an internal
combustion based one, since the engine is unaffected
by altitude, and the propeller only is minimally affected.


Now.. If you plan to regularily turn on the engine
and shake for 2-3 hours, then you should buy a Cessna.
The self sustainer concept (in general) was meant as
a way to get home that one day in the year when the
thermals end and you have only flown 800 out of the
planned 1000 km. It was not meant for regular use.



They have already designed this - the 18 meter model!

-The 18m wingtips for the 20E have been removed from
the options list due to lack of costumer interrest.
The 18T will, as previously mentioned utilize a stinky
engine

It sounds like some pilots would accept the shorter
range in exchange
for the simplicity and reliability of an electric system,
just as some
pilots have accepted the shorter range of the 20E.

-I would not base my whole sales strategy on that estimate.

With a motor and a battery back one-third the size
of the 20E, it would
cheaper;

-Motor and battery pack 1/3 the size of the 20E would
yield a very short range, but have a dissapointingly
small effect on the end price of the product. For the
batteries; we have a very good deal with the manufactures.
For the engine; material cost is not the driving factor.
An engine 1/3 the size of the EA42 will not have 1/3
the price. What is also forgotten here, is that the
propulsion system consists of a lot more than just
batteries and engine. All the other systems, like charger,
power electronics and main computer would not be effected
at all by the 1/3 effect.

I am curious: how did the factory decide the market
was too
small? World wide pilot survey? Focus group? Wild guess?

-Tons of experience, logic and deduction I presume


Andor