Solar powered paraglider

[Mario,South Africa]

Hello everyone. Anybody who knows if the following is possible?
I am a Paraglider Pilot (Glorified parachute) and I am busy with my
Paramotor license. (A Paramotor is a paraglider with a small engine+prop
(0.8m - 1.3m) carried on the pilot's back which gives 40-50Kg force with a
12-20KW engine. The whole thing weights about 20-25Kg). My idea is to
replace the internal combustion engine with a electric one of similar weight
and power. Now If you don't know anything about paramotors - I only need
12+Kw (and 40 or so Kg of push) for a minute or so during take off. In
normal flight 4-8Kg of force is enough to keep me in the air ! Because of
this the internal combustion engine is build very light with no proper
cooling (does not need to anyway). I have found a suitable engine within
minutes on google (15KW max for a few minutes 7KW continuous at 36v (48v)
and only weights 10Kg !) Also the propeller can be made bigger to increase
efficiency (a 1.5m - 1.8m max which will give approx. 6Kg - 8Kg force per
Kw) I intend on using a super cap for the 30 seconds or so of extra take off
power (they are plenty within the weight limit which stores enough for the
short time) . The only thing I don't have is a light, flexible solar panel
aprox. 3x9m to work into the upper surface of the glider/wing. I thought the
power can be carried thru the control lines to the engine/cap. It must be
around 12% to 15% efficient to give me the 2.5Kw or so I need for the
electric motor which in turn will convert 90% or so to mechanical energy
(turning motion for the prop). Any ideas?

 

[Mario,South Africa]

Huh buddy, first thanks for bothering to answer. Secondly if I manage to
get under a cloud I won't bother about solar anyway That's the beauty
about the system. The 2 energy sources (wind and solar) complement each
other perfectly when used like described. Cloud above means thermal
underneath (most of the time) - so no worry there. Here in South Africa's
semidesert region where I (un)fortunately reside, clouds are scarce, to say
the least, that's why I am thinking solar (more then plenty) I have found
all the 'ingredients' on the Internet to build a hopefully flyable thing -
apart of the solar generator part. I've found that too (flexible and enough
power believe it or not) the problem is weight ! I can 'absorb' 10-15 Kg on
the top side of the wing, but the flexible solar cells I've found are more
like 85Kg ! ! !
Here is the one link
http://www.siliconsolar.com/shop/catalog/Flexible-Solar-Panel-10-Watt-p-54.html
if this (weight) can be somehow sorted out then I don't see any other
problems to build my 'Dream-Machine'. I have also come across a French site
which builds Electric paramotors using Nicd/Ni-mh batt.(good for about 15min
power)
By the way I am a qualified electronic technician and paraglider pilot
so I have a good Idea what I am talking about. Please help me with a link or
something to a lighter flexible solar panel.
Greetings from South Africa,
Mario

 

[SJC]

Huh buddy, first thanks for bothering to answer. Secondly if I manage to
get under a cloud I won't bother about solar anyway That's the beauty
about the system. The 2 energy sources (wind and solar) complement each
other perfectly when used like described. Cloud above means thermal
underneath (most of the time) - so no worry there. Here in South Africa's
semidesert region where I (un)fortunately reside, clouds are scarce, to say
the least, that's why I am thinking solar (more then plenty) I have found
all the 'ingredients' on the Internet to build a hopefully flyable thing -
apart of the solar generator part. I've found that too (flexible and enough
power believe it or not) the problem is weight ! I can 'absorb' 10-15 Kg on
the top side of the wing, but the flexible solar cells I've found are more
like 85Kg ! ! !
Here is the one link
http://www.siliconsolar.com/shop/catalog/Flexible-Solar-Panel-10-Watt-p-54.html
if this (weight) can be somehow sorted out then I don't see any other
problems to build my 'Dream-Machine'. I have also come across a French site
which builds Electric paramotors using Nicd/Ni-mh batt.(good for about 15min
power)
By the way I am a qualified electronic technician and paraglider pilot
so I have a good Idea what I am talking about. Please help me with a link or
something to a lighter flexible solar panel.
Greetings from South Africa,
Mario

These people specialize in flexible thin film, along with other companies.
http://www.globalsolar.com/
The power output is less than silicon wafer type and the cost is quite high,
but they are flexible and can be light if you can do without the heavy backing
on the panels for mounting and prolonged weatherproofing.
But if you only have say 10 square meters of area, you could only get maybe
500 watts. Not enough to power your 10kw motor. So now you have batteries
and the solar is just to prolong flight.
Batteries could be 30 pounds per kilowatt hour, so you might need 150 pounds
of batteries for 1/2 hour of flight and the solar would only extend that for a bit.
If you can handle 150 pounds of batteries, it might be better to go with batteries
alone rather than an expensive solar array, that can only assist just a bit.

 

[SJC]

Maybe a little ducted fan brushless dc motor like the model jet planes
use on a glider? I used to see that little BD5 Silver Bullet jet at air
shows... it seemed to really get around on a 75 pound thrust turbine.
How much thrust would you need to climg in a glider?

Well..weight, thrust, lift and drag..the fundamentals. I recalculated
that he might get by with just 40 pounds of NiMH for maybe 1500
watt hours. If that would give him 20 minutes of flying and 10 minutes
of recharge time from a generator and battery bank, then he is in business.

 

[Mario,South Africa]

Thanks for the replies everyone. As I've mentioned before, the
technology to make this viable - is here already. No brake thru is
necessary. To summarize: I need about 500Newton (50Kg push) to take off (100
feet ground clearance/height as asked by the authority). I know this is a
lot but is only for take off ! ( To reach 100 feet with that kind of power I
need around 30 sec.) I am not sucking this out of my thumb. I have practical
examples. Thousands of paramotor pilots do just that but with a internal
combustion engine. After take off the power usage goes down - ways down. For
level flight the throttle is only depressed for 10% - 15% . On many a
occasion if the idling is set a bit high, the pilot must 'kill' the engine
otherwise he won't be able to land As tested on a petrol engine by our local
club, a static trust of 50 Newton will suffice in most circumstances for
level flight ! Also there is a ratio between the prop size, revs and trust
generated. I am not going into technicalities, - trust me, no problems
there. The only remaining nag is solar panel weight. Panel size and current
transportation has all been worked out and passed with 'flying colors'.
There are flexible panels as you read this (a bit expensive thou but not
'unobtainable') their weight is a big problem thou. I need at least 100W/Kg
of solar panel ! Ful-Stop. All what I got with today technology is 40W/Kg !
If build with such heavy panels the canopy will be 10x heavier than normal.
Now that should not be a physical problem to hand carry around but when it
comes to flying that canopy will be so fast no human been can use it in a
foot launched device. (Unless I can run at 70+ Kmh) Also the speed will pose
a huge problem when landing ! Even with a stall flare it will still be
moving at 50 or so Kmh. Trust me - is not practical. The electric motor
outputs almost 1000W/Kg, the Supercap is again close to that (for the short
time needed for take off). The solar panels - well best I've found are less
then 40W/Kg :-(

Maybe a little ducted fan brushless dc motor like the model jet planes
use on a glider? I used to see that little BD5 Silver Bullet jet at air
shows... it seemed to really get around on a 75 pound thrust turbine.
How much thrust would you need to climg in a glider?

Well..weight, thrust, lift and drag..the fundamentals. I recalculated
that he might get by with just 40 pounds of NiMH for maybe 1500
watt hours. If that would give him 20 minutes of flying and 10 minutes
of recharge time from a generator and battery bank, then he is in business.

 

[George Ghio]

You might find this of interest:

<http://www.solarparaglider.com/>

 

[SJC]

Thanks for the replies everyone. As I've mentioned before, the
technology to make this viable - is here already. No brake thru is
necessary. To summarize: I need about 500Newton (50Kg push) to take off (100
feet ground clearance/height as asked by the authority). I know this is a
lot but is only for take off ! ( To reach 100 feet with that kind of power I
need around 30 sec.) I am not sucking this out of my thumb. I have practical
examples. Thousands of paramotor pilots do just that but with a internal
combustion engine. After take off the power usage goes down - ways down. For
level flight the throttle is only depressed for 10% - 15% . On many a
occasion if the idling is set a bit high, the pilot must 'kill' the engine
otherwise he won't be able to land As tested on a petrol engine by our local
club, a static trust of 50 Newton will suffice in most circumstances for
level flight ! Also there is a ratio between the prop size, revs and trust
generated. I am not going into technicalities, - trust me, no problems
there. The only remaining nag is solar panel weight. Panel size and current
transportation has all been worked out and passed with 'flying colors'.
There are flexible panels as you read this (a bit expensive thou but not
'unobtainable') their weight is a big problem thou. I need at least 100W/Kg
of solar panel ! Ful-Stop. All what I got with today technology is 40W/Kg !
If build with such heavy panels the canopy will be 10x heavier than normal.
Now that should not be a physical problem to hand carry around but when it
comes to flying that canopy will be so fast no human been can use it in a
foot launched device. (Unless I can run at 70+ Kmh) Also the speed will pose
a huge problem when landing ! Even with a stall flare it will still be
moving at 50 or so Kmh. Trust me - is not practical. The electric motor
outputs almost 1000W/Kg, the Supercap is again close to that (for the short
time needed for take off). The solar panels - well best I've found are less
then 40W/Kg :-(

I think the electric motor is more controllable than a gasoline engine,
this would be a good thing to have. I good brushless permanent magnet
3 phase would provide good power to weight.
I still think a good NiMH battery bank quick charged from a larger
battery bank in the back in a truck would be more practical. Solar panels,
even if you can get CIGS with just a kapton substrate, would be too heavy
and very expensive. 1 kwh might cost more than $20k and the changes to
the characteristics of the wing would be significant.

 

[Bob W]

There are flexible panels as you read this (a bit expensive thou but not
'unobtainable') their weight is a big problem thou.

If I were you, I'd test just *how* flexible these are before buying a
full set. Being able to be rolled up and unrolled from time to time is
a lot different than the constant flexing that (I imagine) they would
be subjected to in your proposed application.

 

[Anthony Matonak]

... After take off the power usage goes down - ways down. For
level flight the throttle is only depressed for 10% - 15% .

Perhaps you could explore an electric hybrid setup in place
of solar PV. Get a gas motor that produces only 10% or so
of the takeoff thrust, just enough to cruise. It'll be much
smaller and lighter than the normal engine. Add an electric
motor and lithium batteries to provide that 30 seconds or
so of power for the takeoff. Use one of those fancy torque
converters like Toyota uses in the Prius.

Then again, you might want to do a websearch on the term
"Solar Paraglider".

http://www.solarparaglider.com/

Anthony

 

[Al]

There are flexible panels as you read this (a bit expensive thou but not
'unobtainable') their weight is a big problem thou. I need at least
100W/Kg of solar panel ! Ful-Stop. All what I got with today technology is
40W/Kg ! If build with such heavy panels the canopy will be 10x heavier
than normal.

Hand-in- hand with these estimates are your maximum insolation levels. The
output from any array (assuming optimum array angle at all times) will be :
(insolation amount per square meter) * (panel efficiency).

A reasonable "guesstimate" for S.A. on a good sunny day would be ~1000w /
m^2 (or perhaps a bit more), and you won't get any better than ~10% with
flexible systems. You want to be able to provide 7kW continuous, therefore
you need

7kW = (~ 1000w/m^2) * (10%) * 70 m^2.

Ignoring the weight, would this area be too big? More info available from :
http://www.pv.unsw.edu.au/links/related/

Good luck with your project.

Al

 

[Mario,South Africa]

Thanks for the links buddy.
It looks like i have to use a 'oversized' glider. Now there are plenty out
there (used for tandem flying with total take off weight between ~130Kg min
and 230Kg max all up !) A 'oversized' glider has 2 big advantages ( lower
minimal sink rate - therefore needs less power to stay up 50+% less and
offers a bigger area for solar cells almost 40 m square usable area versus
25 ! ) The down site is - less forward speed - therefore less
maneuverability in somewhat less stability because the wing load is less.
Also they are not so easy to inflate ! but all that is easy manageable with
a bit more ground training. (Tandem pilots are doing it day in and out after
all). And I don't need 7KW to fly ! ! ! With a 1.5m properly designed prop
500rpm should suffice to keep me up in a 45m square glider. With a bit of
math's it turns out that 3-3.5KW is all it takes ! Anything more than that
and I will go up or I can use to recharge the Supercap (It will be empty
just after take off). I need about 10 -12 KW for 40 or so seconds to take
off (100 feet ground clearance) after that . . . If there is no wind I can
take off with the sun behind me to maximize the angle to the top of the
canopy (it will be close to 90deg if I take off around noon ! ) If the solar
panel gives 5 KW and the supercap another 5 for a min or so then I am in
business ! ! !
Greetings from South Africa,
Mario

 

[[email protected]]

Reading all the replies I got another crazy idea for you...... How about
using roll up type solar panels and hang it as your tail rather then
installing it on your wings or canopy whatever you call it. Use the battery
power for 30 seconds to get off from the ground, once up in air inflate the
roll up panels attached to you and it hangs like a tail to you in right
position, It is no biggie to design a lil mechanisum to keep it in upside
position. Before landing just roll em up again as you don't need any power
in landing. Its kinda same idea what they use in space craft. Once up in
space ...they inflate their solar wings and get all the power.

 

[Bill Cotton]

Reading all the replies I got another crazy idea for you...... How about
using roll up type solar panels and hang it as your tail rather then
installing it on your wings or canopy whatever you call it. Use the
battery power for 30 seconds to get off from the ground, once up in air
inflate the roll up panels attached to you and it hangs like a tail to you
in right position, It is no biggie to design a lil mechanisum to keep it
in upside position. Before landing just roll em up again as you don't need
any power in landing. Its kinda same idea what they use in space craft.
Once up in space ...they inflate their solar wings and get all the power.


news:[email protected]...

Interesting, I bought a folding solar panel, five watts for my bicycle.
http://www.billcotton.com/quest_on_bicycle.htm One thought was to let it lay
on my rear rack and pack and extend in the breeze. Several problems, one is
my body shadow when riding into the sun, another would be attaching each
time I unpack.

 

[ThinMan]

Interesting, I bought a folding solar panel, five watts for my bicycle.
http://www.billcotton.com/quest_on_bicycle.htm One thought was to let it lay
on my rear rack and pack and extend in the breeze. Several problems, one is
my body shadow when riding into the sun, another would be attaching each
time I unpack.

This guy is in your neck of the woods. It looks ery promising...if you
can get your hands on it!
http://www.scienceinafrica.co.za/2004/november/energy.htm
and
http://peswiki.com/index.php/Directory:Vivian_Alberts_thin_film_solar#Ab
out