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All FLPHG stuff goes here
User avatar
By mlbco
#371808
My friends and I converted my Millennium hang glider to an electric powered ultralight using low cost RC components from Hobby King. The design uses removable twin motors (Turnigy Rotomax 150) and the Turnigy 250A speed controller. The batteries are 14S x 40 AH Li-Po and the props are Xoar 30x12".
Today was the first test flight of the system and everything worked well. We limited the climb power to 100A per motor to avoid any possible issues with overheating the motors and controllers. The max rate of climb was between 300-400 fpm at this current limit but could be much higher with increased current draw. I was able to cut power at 300 ft AGL and climb 1000' in a thermal which was great fun, but not a good day for measuring power consumption because of the turbulent nature of the air.


Here's a video of today's test flights:

[youtube]
[/youtube]

Steve
User avatar
By mrcc
#371811
NICE I like :thumbsup:

Where about do you store your batteries ? How much C of G adjustments did you need to do ?
User avatar
By mlbco
#371826
mrcc wrote:NICE I like :thumbsup:

Where about do you store your batteries ? How much C of G adjustments did you need to do ?
The batteries are in the white box behind the pilot's headrest. They are exactly balanced by the 2 motors on the front of the wing and no other CG adjustments are required.


Steve
User avatar
By dayhead
#371828
Do you have a way to jettison the battery pack? If not, can you eject?

I would want a way to get either the battery or myself outa there in a hurry.

Risk of fire may not be great, but it's definitely there. Just sayin'....
User avatar
By mlbco
#371830
dayhead wrote:Do you have a way to jettison the battery pack? If not, can you eject?

I would want a way to get either the battery or myself outa there in a hurry.

Risk of fire may not be great, but it's definitely there. Just sayin'....
There is no battery ejection capability on the aircraft. If they were ejected the aircraft would be difficult to fly with the large CG shift and then you'd probably need to rely on the parachute for safe recovery. There is a master cut off switch, a Kevlar battery box but not much more.

I understand your concern regarding a battery fire, but the electric automobile industry has shown that this issue is best handled with safety features in the pack itself, at least that seems to get the safety on par with gasoline storage. We don't have an auto-safe battery system either but we have some protection against mechanical damage and thermal runaway.


Steve
User avatar
By mlbco
#371831
Just to be clear, this is a one-off home made project, not a production retrofit for existing Millenniums or other hang gliders!

Steve
User avatar
By Takeo77
#371840
Steve,

That is completely cool, little disconcerting to hear RC airplane sounds come from something you can ride in!

:mosh: :popcorn:
User avatar
By Skyvine
#371852
Looking good, Steve!

Just curious, how much power-on climbing were you able to put on it before needing the generator recharge session?

Keep up the awesome developments!
User avatar
By mlbco
#371860
Skyvine wrote:Looking good, Steve!

Just curious, how much power-on climbing were you able to put on it before needing the generator recharge session?

Keep up the awesome developments!
Brian Porter and I flew a total of 23 minutes on 3 flights. One of those flights included thermalling with over 1000 ft altitude gain. 40% of the battery energy remained after the 3 flights. The charging we did in the field added only 10% of the total pack energy, and was not significant.

My estimates show one 3000 ft climb on a charge or 30 minutes of level flight cruise. We only carry 31 lbs of batteries.

Thanks,

Steve
By freeflight
#371867
mlbco wrote:
Skyvine wrote:Looking good, Steve!

Just curious, how much power-on climbing were you able to put on it before needing the generator recharge session?

Keep up the awesome developments!
Brian Porter and I flew a total of 23 minutes on 3 flights. One of those flights included thermalling with over 1000 ft altitude gain. 40% of the battery energy remained after the 3 flights. The charging we did in the field added only 10% of the total pack energy, and was not significant.

My estimates show one 3000 ft climb on a charge or 30 minutes of level flight cruise. We only carry 31 lbs of batteries.

Thanks,

Steve
Is the overall weight of this system comparable to the gas version? A little lighter maybe?
User avatar
By mlbco
#371869
The electric system weighs 40lbs, less than half the weight of the gas engine system I also use on this wing.

Steve
By freeflight
#371871
mlbco wrote:The electric system weighs 40lbs, less than half the weight of the gas engine system I also use on this wing.

Steve
Wow that's impressive!
User avatar
By Mr Pou
#371890
mlbco wrote:Just to be clear, this is a one-off home made project, not a production retrofit for existing Millenniums or other hang gliders!

Steve
Do you intend to go into production or sell the IP if this thing works out?
User avatar
By mlbco
#371894
Mr Pou wrote:Do you intend to go into production or sell the IP if this thing works out?
My friends and I owned Bright Star Gliders where we manufactured Swifts and Millenniums (class 2 rigid wing hang gliders) from 1992-2002 and we have no intention of getting back into the hang gliding business, there is no money in it!!

The electric motor set up is completely off the shelf and there is no IP so far as I'm concerned, that's why I'm happy to share any info I have on the web. From an engineering standpoint the project has already worked out, the aircraft meets the performance estimates and has survived the first flight tests. Now we can refine it a bit and just go fly.

One possible goal for the system is to foot launch it from our coastal ridge site on a windy day enough and use the motors to cross gaps in the ridge to make it to other parts of the coastline that are usually inaccessible. For example, crossing the Golden Gate Bridge from Fort Funston to Mt. Tam :)

Steve
User avatar
By red
#371896
Mr Pou wrote:
mlbco wrote:Just to be clear, this is a one-off home made project, not a production retrofit for existing Millenniums or other hang gliders!
Steve
Do you intend to go into production or sell the IP if this thing works out?
Mr Pou,

Got a Millenium?

With any "conventional" HG, with the pilot swinging freely below the wing, you can't apply power to the wing like that. It's been tried, and it causes a tuck, even in rather minor turbulence. During launch or landing, or when just flying low, any tuck can be extremely hazardous.

The thrust line (for a HG) needs to go through the pilot to be safe, such as the way that the Mosquito or Doodlebug harnesses are designed. An electric Mosquito or Doodlebug should be coming by here, almost any week now. :lol: I would want a folding prop, of course.

:mrgreen:
User avatar
By Mr Pou
#371897
red wrote:Mr Pou,

Got a Millenium?
Of course not, I'm just starting in the sport :lol:

But I did go to the bible to look it up and it appears to be an interesting recumbent type of a rig. As an engineer I like looking at the interesting things people do.
An electric Mosquito or Doodlebug should be coming by here, almost any week now.
So, you're buying one? They look interesting in concept, and if I lived in flatlands I'd probably look, but luckily there are a couple of decent hills nearby to fly.
User avatar
By BBJCaptain
#371938
Great work Steve :thumbsup:

Are the motors attached to the cage?

Keep up the great work :mrgreen:
User avatar
By mlbco
#371939
BBJCaptain wrote:Great work Steve :thumbsup:

Are the motors attached to the cage?

Keep up the great work :mrgreen:
The motors mount to the wing so that I can install my fairing without punching holes in it. We added reinforced nut plates inside the D-tubes so that the motors can be mounted with 4 small screws.

Thanks,

Steve
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