Thanks for the info
so wow it would be about one 30kg fuel cell per motor. 120kg(264.555 lbs) of dead weight.
The 1kw fuel cell is 4kg you would need 17 of them at 68kg (149.914 lbs) bit of a difference but mounting them all… at the cost of a 75k luxury car.
You may as well make some really big wings and try flapping with your arms…
I wonder what motors the fuel cell drone used and its current draw as It has 8 motors… It doesn’t sound possible at this point.
Edit: it uses an “H2 fuel cell” that’s 800w and 1.6kg. i dont see it working. not with 8 motors.
I collected that data static but I have my amp meter mounted on the gooseneck bar so I can watch it during flight. I was surprised to see the same numbers during flight but it made me realize that our flight speed is too slow to see a difference between static and dynamic.
We took it up to 44 mph with snow skis but too busy watching for other tracks (as to not wipe-out) and measuring the speed with GPS. I imagine that would make a difference with amps but it wouldn’t be relevant.
Guys can you check something for me? My calcs wrong? Converting HES’ aerostak 250 and a 20L tank to Wh equal to a stack of 8 22000mAh 6s bonkas…
So more power, less weight… I mean if relationship is linear doubling flight time and cutting weight in half would make finding the pure hydrogen for fuel all worth it. No? These numbers are so absurd did I convert this right? I’m not an engineer.
Hi there.
Unfortunately it is not just the Wh’s (which is a measure of the ‘capacity’ of an energy system).
OpenPPG has high ‘power’ requrements (which is how much energy can be delivered per second).
Have a look around at all the good work from others, but to summarise:
You want (peak) power supply of about 4.3kW per motor. Even ‘cruising’ you want something like 2kW per motor (e.g. 2.4kw. You need 4x their most powerful unit, which weighs in at around 13kg (and uses lots of space). Then add a gas cylinder (umm, where?).
I’d also be feeling uneasy about strapping compressed hydrogen to my back when you could stumble on landing…
I think there’s nothing for it, but to wait more for battery tech.
Hi thanks for the reply! Didn’t notice the 4.3kW per motor stipulation. I just saw that the power output was averaging 300 amps. I missed DarkLinX5 and Dpack’s comment feb 6th. My bad.
The https://www.intelligent-energy.com units are actually pretty interesting if you were to use them as a hybrid system in tandem with batteries. You could seriously stretch cruise times by taking 4.8kw of load requirement off your batteries for about 8kg of fuel cell, but from what I can see, it would be extremely expensive (multiples of $10k).
Just to shut-down the concept of H fuel cells for ppg in-flight, and avoid others wasting their time!
I was busy getting excited about energy density (Wh/kg), and thinking about hybrid systems with batteries, etc etc.
Then I realised:
H at 300 bar is only 0.7 kWh/l (http://www.fcway.com/hydrogen_mainpage_eng.htm)
Level flight is over 6 kW.
i.e. 1 litre gas bottle gives you 6 minutes of level flight.
I think the volume needed to mount gas bottles, plus fuel cell, plus ‘peak power’ batteries makes this approach infeasible. Hydrogen fuel is great per kilo, but terrible per litre!
I found a very thorough analysis which comes to pretty much the same conclusion: for small craft, wait for batteries. https://repository.tudelft.nl/islandora/object/uuid:6e274095-9920-4d20-9e11-d5b76363e709/datastream/OBJ/download
