Earthstar Forums

Okay Rahul, I finally deciphered your email: KD72401 is a DC motor
controller, NG5 is a battery charger, right?

Another factor we have to consider is that to get full efficiency in an
eGull we will have to cowl the motor and use an efficient spinner. I was
talking to Mark about all this and he said that with the reduction of drag
possible due to not needing to cool a heat engine (up to 30% of the engine
output is wasted on this), the ability to pitch the prop to its most
efficient angle of attack (torque) and the ability to design a very high
efficiency engine cowling, will make a 50 hp motor on an eJT2 or eOdyssey
equal an 80-85 hp engine. To further increase cowling efficiency I have a
special spinner that has a long tapered "end" that reaches a couple of feet
behind the engine. This spinner does not make sense w/o a very good cowling
that leaves no gap behind the engine/motor but would make sense with a
eGull.

Decreased drag makes sense for cruise, but I'm not sure I agree (given my
level of understanding) in the low drag areas of pre-flight and flight
(takeoff and climb). It seems there a 50 hp motor will give the same
performance as a 65 hp engine. But our aircraft should be substantially
lighter even w/ the batteries.

This whole conversation is why, assuming batteries improve as fast as I
believe they will, I will not buy a 4 cycle engine to replace my current 85
hp 2-cycle. I'd rather wear this engine out and replace it with a battery
and motor combination that would give me 3 hours of flight plus reserve and
be chargeable by a standard FBO 220V system (which I'm sure almost FBOs have
and would make available upon request and planning). Spend three hours in
the air (say 6am to 9am), start recharging the battery, eat breakfast, prowl
around the airport, eat lunch, fly three more hours late in the afternoon
after the thunderstorms have died down. Land and camp/motel while the
batteries are charging overnight and you have a plan for a great multi-day
flight.

P.S. Add 1# for a electric powered air horn to warn birds in the the air
and animals/people on the ground of your presence, 1# for some sort of
device that measures the KWs of energy put into the batteries (so you can
pay the FBO), and 5# for a large diameter 220V extension cord. So much for
all the airplane haters who complain that airplanes are noisy. I can't wait
until my airplane whispers into a backcountry airstrip, say on the Middle
Fork of the Salmon (might need more than 3 hours of battery for that
flight).

-Alan

_____

Yes Alan, Great information. This eJT2, eOdyssey incarnation would be
closer to a Vajra-yana (sanskrit for thunderbolt or diamond vehicle)

got to rethink, so far the thought has been like - even half that
battery pack with a basic lighter kit is pretty good for a beginner to
get the license and acclimatize with half the range, then a couple of
upgrades a year later. This configuration is closer to a second plane
i had in mind and my wallet so far, in 2020ish with a boat's hull. For
now there are quite a few overdue commitments to plan in the next
couple ears.

-Rahul

Allan,
Ha-ha, on th airhorn! The real fact of the matter, if you've been around the e-Gull, as I was at Arlington the summer before last, it's not going to sneak up on birds. I was supprised to hear how much noise the prop makes, even without the exhaust chiming in. I suppose inside it's quiter because there is probably less transmitted vibration, but it's not stealth, like a Prius chugging around the corner on batteries only. By the way, the government is considering having the electric car mfgr's come up with noise makers, (I would have a recording and speakers of an exotic Ferrari or something).
The other point you make is about the big spinner and efficent cowling, such as on Mark's e-Gull. If you check out my photo's, I mounted a huge long spinner behind my cowled up 503. I can't say that I've noticed any significant airpeed increases, but it sure makes the plane look modern compared to clunky old school ultralights. And 50hp is the number I'm looking for also, as you have mentioned it will perform like an 85hp gas engine. That's what I want, and I starting my cookie jar savings!

kb

hehe, Kessss, it will -- with the direct drive, a neat prop like the
duc whirl or the elippse one day and that cruise speed. maybe at low
altitudes it'll be better to not honk at all at the birds at least.
wonder what the Audubon society would recommend for electrics

rc

Aha! The Audubon Society, I suppose they would want a noise maker that would sound like a very large bird!! Squawk! Squawk!!

kb

Well Kess, this would mean that you could go back to flying inverted without the worry of an engine out!
Fred

Yay!!