FES climb rate question.

kinsell wrote on 10/12/2020 11:40 AM:
On 10/12/20 8:46 AM, kinsell wrote:
On 10/8/20 6:54 PM, 2G wrote:
On Thursday, October 8, 2020 at 1:14:30 PM UTC-7, Mana wrote:
You'll get at least 2m/s dry. But like PF says, better to take a tow to 400m and use the
FES straight and level until you find a thermal. It's much more efficient in level flight
than climbing.

On the Shark, based on a test flight I think that you will get less than 2m/s as it is a
heavier glider than Matthew's Diana 2 :-).

*From the FES manual:
5.3.4.1 Rate of climb
The* maximum rate* of climb* is* available* only* for* a* few minutes* with* fully* charged
battery packs. As battery voltage is reduced, the maximum achievable climb rate is lower.
The average rate of climb depends mostly on the type of sailplane and its take-off weight.
Maximum attainable altitude gain that in standard atmosphere conditions depends on the
type* of* sailplane,* its* weight* and aerodynamic* qualities.* To achieve the maximum
altitude* gain, use about* 15kW* of* power. Do* not* use* full* power* as* the efficiency
of* the system* is* lower. Usually, 80-85* km/h is* best for the* climb with positive flap
setting (the same setting as used while thermaling). Here are rough numbers:
•1600 m (5200 ft) for UL sailplanes at 300kg take-off weight, i.e. Silent 2 Electro
•1400* m (4500* ft)* for* the* 18m* class* sailplanes* at* 400kg take-off weight* (without
water ballast), i.e.LAK17A FES
•1200* m* (3900* ft) for* the* 18m* class* sailplanes* at* 450kg take-off weight* (without
water ballast); LAK17B FES, Ventus 2cxa FES, Discus 2c FES, HPH 304ES

Sounds like a very marginal self-launch system and is really just a decent self-retrieve
(turbo) setup.

Tom


These gliders are sustainers only.

Looks like the Silent 2 is rated for self-launch.

As is the miniLak FES, also a 13.5M glider. It works well for them because they are lighter
than the 18M gliders.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1