Dne nedelja, 23. september 2012 20:01:53 UTC+2 je oseba Eric Greenwell napisala:
On 9/23/2012 10:16 AM, John Cochrane wrote:

From an engineering standpoint, I don't really see why the electrics

don't also charge the battery. If you climb to 3000', in 20 minutes,

surely running the prop in generator mode for 20 minutes or so,

doubling your sink rate temporarily, should recharge the batteries?

This could make a 3000' capacity enough for self launch and

retrieve!.



I haven't heard a designer discuss this, but it is intriguing. My guess

is the cost and the complexity are great enough, it's a better tradeoff

to increase the battery size from a 3000' climb capacity to a 5000'

climb capacity, so you still have 3000' left after a self-launch. The

Silent and similar electric gliders have about that climb capacity; in

fact, I think they allow you to choose the climb capacity by buying

additional battery packs.



--

Eric Greenwell - Washington State, USA (change ".netto" to ".us" to

email me)

Vote is between sustainers, not including selflaunching systems! Sustainers have all very similar weight, and also pricing. The difference is in mainly in range, noise, operation, maintenance etc.

Just a few comments:
1.Manufacturers would like to produce what they will be able to sell, but is not obvious what pilots will choose. So that is the reason of this voting!
2.Using prop in regenerative way is not really efficient (maybe 5%) due to wrong airfoil curvature for this mode.
3.At Silent Electro (FES) is not possible to chose between two different packs, as this would change CG position and also total voltage of cells, and caused some additional problems. Silent can climb about 6500' with only 30kg of batteries which is more than enough. Adding more batteries would be just more costs and more weight.

Regards,

Luka Znidarsic, designer of FES system