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Apr 13, 2013, 06:20 PM
I buy ikarus piccolo/Eco8 stuf
helifrek's Avatar
Thread OP

Need help calculating thrust and runtime for electric hang gliding

Hey guys,
I know I could use the E-calc but from where I am currently at, I cannot access it. Nor can I access some of the sites to get more detailed information on the motor, speed control and batteries. So if you guys don't mind, I could use a little help.
I am on my way to becoming a certified hang glider pilot and in the future I would like to get into foot launched powered hang gliding (strapping a motor to my butt so I can take off from flat land ) There are units out there for sale that are fuel powered and cost around $5,000 which is alot of money! I know alot of the powered paraglider guys are making their own electric powered harness' and I would like to do the same, although a hang glider is going to require slightly more power to be feasable. There is one hang glider pilot that I found using electric power but as far as I know he cannot take off from flat land, the electric only assists a little bit.
On to the motor/batt/esc setup....

Motor: Turnigy Rotomax 150cc
Batteries: 7S 5000mah wired together to make either a 14S 10,000mah or 20,000mah depending on weight.
Esc: I hear the Turnigy Dlux 250 is better than the 300A one HK has available.
Prop: the biggest I can find are 32x10

I would provide more information on each item but I cannot access hobbyking from this server.

So, what kind of thrust could I expect with this setup, what kind of runtime?

The glider plus my weight will weigh around 275-300lbs. minimum takeoff speed is basically as fast as you can run stall speed is very low although I don't know the exact number (maybe 10mph). I would need enough power to push me up to at least 1500-2000ft agl at least one time. Enough runtime to do that about 3 times would be great, or enough to climb to 4000-5000ft would work too. Takeoff would be at full throttle until a safe height of about 200-300ft is reached.
I hear the Gas powed units produce 110lbs of thrust or so, and I am told 100lbs is the absolute minimum thrust required. So, if I can get at least 110 that would be good as well as a runtime of maybe 15-20min. I have 15 years expierence in RC so building the rig will be easy. I don't want to start the project unless the numbers look promising because this thing isn't going to be cheap
Please feel free to give your suggestions and advice and ask questions about anything. Hang gliding is a pretty safe sport, Alot of people build their own powered harness' I just haven't seen many electric ones and I would like to develop something affordable and easy to build so more people can enjoy FLPH (foot launched powered hanggliding) and help to build the sport up some more. Thanks in advance for any help, I am open to suggestions and modifications. I would like to try and keep the budget around $1500 to $2000 max. build might start this winter if all goes well!

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Apr 13, 2013, 08:35 PM
Registered User
I don't know whether this will help in choosing the proper equipment.

It interested me that it seemed to meet the 50W per pound rule of thumb.

It requires about 5KW for level flight.

Technical data

Harness Weight: 8,5Kg (harness, internal aluminium framerescue system, back protector)

Engine Set Weight: 9,5Kg (engine, carbon frame, regulator, throttle control with cable, carbon composite casing)

Battery Pack Weight: 9Kg (size: 35cmx15cmx20cm, capacity: 25 A/h)
Propeller Set Weight: 1,5Kg (prop diameter 125cm, three carbon blades, head with folding mechanism)

Maximum controler current: 400A / 70V

Maximum engine power: 15kW

Maximum used engine power: 13,5kW

Maximum battery pack voltage: 63V

Maximum propellerRPM: 2350 RPM (three blade 125cm)

Maximum climb rate: 2,2m/sec (Gradient Avax XC3 26, take-off weight 110Kg)

Maximum static thrust 514N (52.5 lbs) at 13.5 kW output

Average level flight power: 4,8kW

Battery pack details: 25Ah Li-Pol, 14S 5P 20-30C, peak voltage 63V, charging time 45-60min

Average powered flight time: 20min (single charge)
Sep 30, 2013, 02:31 AM
Registered User


I already use the Turnigy Rotomax 150cc, with ESC JETI 200Amp, Lipo Nanotech 7S 5000mah x 4 makes 14S, prop from 30inch to 27inch, all but fail to meet more than 30 seconds of full thrust (+- 20kg of static thrust).
Perhaps its my mistake since one person from Denmark stated that maximum throttle only allowed for a few seconds for takeoff than reduced to below maximum for climbing. Still testing thou...
Keep up the good work
Sep 30, 2013, 07:49 AM
Lift is cheap - Drag sucks
Tom Harper's Avatar

Is your rig flex or rigid wing?

Assuming a flex wing, a first approximation of the problem (using typicals) is:

L/D ratio ~ 12

Weight 280 pounds

Drag ~ Weight / (L/D) = 23 lbs

From the APC prop data for a 27" dia 12" pitch prop:

25.6 pounds thrust at 32 MPH (Flex wing typical) requires:

6000 RPM with a shaft power of 4252 Watts ~ 5000 Watts input (80% efficiency)

At 7S that's 214 Amps or 214000mA to sustain level flight

Ampere Hours of battery = (Current X Desired time) / 60

Ah = (214 X 1 minute) / 60 = 3.6 Ah per minute of level flight

So a first approximation is that a good quality 7S 3600mah pack would give you 10 minutes of level flight


Last edited by Tom Harper; Sep 30, 2013 at 12:08 PM.
Sep 30, 2013, 11:17 PM
Registered User
Originally Posted by Tom Harper
At 7S that's 214 Amps or 214000mA to sustain level flight

Ampere Hours of battery = (Current X Desired time) / 60

Ah = (214 X 1 minute) / 60 = 3.6 Ah per minute of level flight

So a first approximation is that a good quality 7S 3600mah pack would give you 10 minutes of level flight

At 214 A and a 3.6AH battery, wouldn't that be 1 minute of flight?
Oct 01, 2013, 08:39 AM
Lift is cheap - Drag sucks
Tom Harper's Avatar
You are correct - I slipped a decimal point. I thought it looked too good.

So, it would require 7S 3.6Ah per minute of level flight.


Oct 01, 2013, 01:06 PM
Registered User
Before there were Trikes we foot launched. 1977. I used a 32' rigid flying wing with tip drag rudders and a McCullough 101 chain saw engine. The 125cc,12.5 hp engine could turn a 26" special made Grish Brothers paddle prop that produced 46 lbs static thrust at 6-7k rpm and 55lbs with a 28" Volmer Jensen prop. The thrust was enough to foot launch into a light breeze with about 100'/min climb. My highest flight was to 2800' with some convergence lift at the beach. The engine,mount,prop and 1 gal gas was 25-30lbs. The cost was around $300. Most of the kites used a "Soar master" that attached to the keel. It used a 10hp engine with a geared down large prop behind the pilots feet. It worked well. The larger prop produced about 100# thrust. Fuel consumption was about 1 gal/hour. I'm not sure because I could not stand the noise for 1 gal of gas. I looked for lift.
It is not a great idea to attempt a zero wind foot launch take off. Hang gliders can do 10mph landings but not 10 mph takeoffs. 10mph wind may support the glider and engine but not you too. You need very good control to run all out with the propellor thrust trying to push the glider faster than you can run. If you trip you pray the prop stays together and the engine doesn't come loose. Be conservative.
Last edited by Plantoflap; Oct 01, 2013 at 01:41 PM. Reason: Wrote 100'/sec climb, meant 100'/min
Mar 20, 2015, 07:58 AM
Registered User
Lets revive this one because it is happening as wqe speak on both sides of the planet.

Search e-help hang glider and you see the NZ guy and the Norwegians successfully climbing with electric power and lipos. The Norwegians are launching from the flat with a fairly inefficient beginner flexwing. The thrust to launch a competition flexwing will be less but it might need a different prop. Technique should be the same as with the available ic power packs though on these the motor weight is supported on skids at the start of the launch run. We will be running with the lipo weight. The Norwegians used a wheeled dolly on a ruinway I think...

10-15 mins of 300fpm climb per charge to enable an unassisted self launch rather than aerotow.
On a good day it is possible to climb out in a thermal from very low - like 300ft or so - and that should become the norm if you can switch the power on and off at will.
Quiet power could be used on conventional sites that are too small to offer a good chance of climbing away without strongish winds, and often meagre ridge lift is over crowded with paragliders these days.

Electric power enables the main power pack weight (lipos) to be on pilot C of G. Unlike ic power units which have a lot of weight near the prop - which then balances the pilot differently so the pilot position is unnaturally far forward when flying unpowered.

Lipo/ESC fire detaching pilot from airframe or disabling pilot. 7Ah of 14S strapped to the harness makes a sort of suicide bomb.

How do you control an ESC with a mouth or lever operated throttle and no R/C set?
Mar 20, 2015, 05:09 PM
Registered User
Fourdan's Avatar
Have a look here the Parawatt motor (french design, excellent outrunner, very robust and high efficiency)
Two Kv (star or delta via connectings the six ends)
Website in french (use google translator)
Mar 21, 2015, 09:04 AM
jackerbes's Avatar
How do you control an ESC with a mouth or lever operated throttle and no R/C set?..."

That is a no brainer, just use a servo tester as a throttle. The knob turns the PWM rate up and down and the motor responds accordingly. Here is my favorite one but you can find servo testers as cheap as 99 Cents on eBay.

Oct 13, 2015, 01:58 PM
Registered User
I spec'd out electric with multiple batteries in a 14s config, but found it to be as heavy as a gas unit. Run time was <20 min.
With gas, run time is about 1 hour per gallon (128 oz).
Here it is with a DLE-222 mounted. Prop not shown here (34x10)
Aug 06, 2018, 03:37 PM
I buy ikarus piccolo/Eco8 stuf
helifrek's Avatar
Thread OP
are any of you guys still around? I know this is an old topic. I am finally out of the Army, I am flying paramotors now (IC powered) I just finished building a 2Kw electric dirtbike (small kids bike but big enough for me) and I got the bug to try and build an electric paramotor rig.

I am eyeballing the revolt 160-pro motor. looks like it might have enough power for me. if I could shed some weight I could probably go with the slimmer version.

prices have come down enough to make this a reality! hoping I can make some progress on this!
Aug 07, 2018, 05:32 AM
An itch?. Scratch build.
eflightray's Avatar
Have a look in this forum --

RC Paragliders and Kites forum

Hopefully they will have the knowledge.

Or are you talking 'full size'.

Aug 07, 2018, 08:07 AM
I buy ikarus piccolo/Eco8 stuf
helifrek's Avatar
Thread OP
Talking full size!
Aug 07, 2018, 02:00 PM
An itch?. Scratch build.
eflightray's Avatar
e-LIFT hang glider electric propulsion system from electricsports. (7 min 31 sec)


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