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emir_82

Well-Known Member
Joined
Jun 25, 2014
Messages
54
Location
Rosario
Hi everyone,

I made this thread to compile the electric drive projects of this forum users.

My current project is a retrofitable electric self launching system for sailplanes.

instagram.com/grasshoppersystem

In the near future i'll starting to manufacture our own motors too.

Regards
 

Bille Floyd

Well-Known Member
Joined
Sep 26, 2019
Messages
242
My first post here :

I fly a rigid-wing , carbon hang glider , with spoilers
for turning and a flap for glide control ; it weighs
100Lb, and i foot launch it with two fake legs and
a 8kt breeze.

This coming year i want to get rid of the pilot down
tubes and control wires ; fit it all in a pod that's
centered in the wing with a 15Kw E-motor, with
a pusher prop that folds , (and a wheel) or two.

I get 17:1 L/d claimed, (15:1 actual) , now ; podded
up i should match a sgs 1-26, at a 45mph best glide
speed. I "Want" 3 good climbs out of the battery
to catch a thermal, kill the motor and fold the prop
and soar away.

Bille

This is me at Torrey pines , San Diego :
 

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emir_82

Well-Known Member
Joined
Jun 25, 2014
Messages
54
Location
Rosario
Bille,

Nice project!
If you still have 15:1 glide ratio at 45mph and assuming 320lbs of total weight you will need a little less than 4kW of electric power (that includes the efficiency loss of battery, controller, motor and propeller) to maintain level flight, so with 10kw you will get a decent climb.
15kW motor will be overkill, but is better to have spare power just in case the maths didn't help at first and the weight difference is very low. Price not so much.

The battery pack will be a little more difficult to design to keep weight low and range high.

Did you start picking the parts yet?

Regards
 

Bille Floyd

Well-Known Member
Joined
Sep 26, 2019
Messages
242
The Exxtacy Hg is old ; but built like a Tank !
Fully cantilevered wing , (no wires or struts needed)
in this carbon honeycomb D-tube , with carbon ribs.
It's a tandem HG good for 160Kg , (358Lb) payload.

I weigh 205 of that 358Lb it's good for ; so i
can add 153Lb of weight and still stay inside
the placard limitations , with a VNE of 58mph.
The wing is already 100Lb ; so i can use all the
153, (for power & pod), that it's weight limitation is
good for, and stay legal under 254 Lb. The more
weight i put on her ; the higher the, "Speed" i get
my best L/D at .

When i put the pilot in the pod , and get rid
of the control-frame & wires ; i fully expect
that 15:1 or 17:1 L/D, to go up to near 20 to 22:1 L/D.

I want 15Kw power because i plan to do most
my flying at King Mt Idaho ; mountain peaks are
12K' ASL , and take-off is at 5,500' ASL. Seriously
i think i might NEED a variable pitch prop , to
clear a 12K' ASL Mt , with some reasonable degree
of success ; even 15Kw power ?? !

BTW - Not a lot of options for reliable, and well made
electric motors , (not like gas engines) ; but i hope
something fits my needs a year from now because
that is how long it will take me to build and test-fly
the pod i wanna use. I'm OK at mold making, and
general composite lamination's. I am not an engineer
but can copy and shape stuff , rather well.

Bille
 

emir_82

Well-Known Member
Joined
Jun 25, 2014
Messages
54
Location
Rosario
Bille,

Electric motors does not loose power with altitude because don't need oxygen.
The propeller does lose some power but is not much a problem.
If you are using it only to climb you can set the pitch of the blade for that mission, there is no need of variable pitch.
I dont know if there is a folding and variable pitch propeller in the market. Featherig and variable pitch propeller is more easy to find.
I'll recommend a fixed pitch foldable propeller because they are less expensive and there is a lot of project around with those.

The electric motors are reliable even the Chinese (some brands). The weakest link is the controller.

How many ft you want to climb in total with the motor?
 

Bille Floyd

Well-Known Member
Joined
Sep 26, 2019
Messages
242
I keep forgetting about how E-motors don't loose power
like the gas engines do , at altitude.

I would say on a good day ; a 500 to 800ft gain , would be
enough to hook into a good thermal. Having power while
searching for a thermal ; that would be a major bonus !

Your right about the folding prop ; for my needs , it's
the way to go.

Has anyone here , ever dealt with this company :

https://www.geigerengineering.de/avionik/produkte

Bille
 

John.Roo

Well-Known Member
Joined
Oct 8, 2013
Messages
402
Location
Letohrad / Czech Republic
I also beleive that electric propulsion makes sense in electric gliders, motorgliders and hang gliders :)


Of course I can start to explain why are the long wings better and how they help to decrease energy necessary for horizontal flight etc... But I am tired to repeat all advantages of high "glider like" wings again and again so... OK, if somebody prefer "airplane" instead of "motorglider" please feel free to use the short winglets and enjoy electric "Red Bull racer" :)

 

emir_82

Well-Known Member
Joined
Jun 25, 2014
Messages
54
Location
Rosario
which brands? what controller do you recommend?
I can't recommend it, because they are Chinese and you never know what happens in their quality check. But I have a freerchobby and works... You may need to rewind it if you burn it because they tend to have less copper than needed.

You will hear a lot of bad things about Kelly controllers. But FES system has more than 200 sailplanes flying with that brand. If you oversize it, you may not have much problems. You may need to learn how to order by the electric RPM that is not the same as the motor rpm.

Regards
 

John.Roo

Well-Known Member
Joined
Oct 8, 2013
Messages
402
Location
Letohrad / Czech Republic
Generally I had not so bad experience with Kelly Controllers.
We did first electric flights with his controller.

But according to my personal experience I recommend you to take whole system (motor, controller, battery, chargers etc.) from one producer (of course if possible). It far not that easy to connect together systems from different producers.... especialy when you need more than 10 kW of power. Another problem is cooling - RC models are flying few minutes. For safe TakeOff you need max. power for few minutes + than you need to climb to safe altitude = also much more power than for horizontal flight.

I am flying with MGM components.
My friend has good experience with Geiger engineering (mentionned already).
Problem of both suppliers is higher price, but if you count all problems and "burned" motors and controllers during testing is maybe not that bad...
I still have some Kelly controllers at home :)

What max. power are you looking for?

Best regards!
Martin
 

proppastie

Well-Known Member
Log Member
Joined
Feb 19, 2012
Messages
4,560
Location
NJ
What max. power are you looking for
first off there is very much I do not understand about E motors....My aircraft is designed around 3w-200 model aircraft engine and stock model propeller currently ground tested with a 32" x 10" at rpm 6000 for takeoff power. 20 hp (reported ?) .....It is a powered launch micro-lift glider with the same platform as the Carbon Dragon. So I am learning about 15 kw and 6000 rpm......as an option if/when I am not satisfied with the 3w-200. Link to the build log below.
 

proppastie

Well-Known Member
Log Member
Joined
Feb 19, 2012
Messages
4,560
Location
NJ
CR FLIGHT electric drive
Still in development so we will have to wait a while....the 100 lb option looks nice, but if it is for quad copter (25 lb per motor ?) I would not be interested.
 
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