FES in Contests

Now that 2014 is over, the time has come to restart the discussion (with the handicap commitee) regarding the handicap calculation for FES equipped gliders (and/or perhaps the handicap debate for sustainers in general).

Right now, as I see the current FES handicaps, it appears that the only factor influencing the current FES handicap is the increase in gross weight. See the Lak17bFES compared to the pure version below. The Lak17b actually has .01 higher handicap handicap than the Lak17bFES. If a any drag was considered, the handicaps would be (at least) equal. I contend an equal handicap is still not enough, but you get the idea.

Manufacturer Model Notes Span Weight Handicap

AB Sportine Aviacija LAK-17B 18 868 0.845
AB Sportine Aviacija LAK-17B FES 18 998 0.835

Additionally, nothing about FES systems is in the SSA Handicap Calculator for example: http://www.ssa.org/ContestHandicaps?show=blog&id=175

I believe that the current FES handicapping is obviously inaccurate. The FES system comes along with a significant amount of drag (2-4% according to FES study) which of course increases dramatically at higher speeds. The nose, the large gap in the nose between the "spinner and the fuselage" and the 18 inch folding propellers themselves are significant objects which clearly disturb the very high pressure airflow. If you don't think so, please, Ill buy you some parts to tape onto the nose of your glider at the next contest so you can prove it to me ;-).

I know the handicap folks are planning on taking a look at the FES handicap.. And I know its a hard job managing handicaps. That said handicaps are becoming more and more important as we are facing more handicap classes in our future. I propose that the FES handicap needs to reflect the significant drag penalty that these gliders are carrying. Clearly, the current handicap ignores the drag and only takes into account an increase in gross weight.

On the other hand, if the counterargument of sustainers having a tactical advantage comes up, I think that is worthwhile winter banter as well. I have no personal concern other than I think the current handicap is clearly wrong, apples to apples.

The argument that the FES handicap is "not important" because few FES gliders are in the US (North America) today is simply not valid. Numerous gliders have been ordered this winter. They are coming! FES is excellent (superior IMO) sustainer technology which is becoming available on more and more gliders. It is only a matter of time before FES becomes popular and the fact that the handicap is not correct is likely adversely effecting its adoption. FES is clearly superior to traditional boom sustainer systems from a practicality and simplicity perspective.

Here are a couple videos.
Video #1 shows the flying portion of a recent study on performance impacts of FES (2-4%): http://youtu.be/o0twY9cWOUg

Video #2 shows the FES system in action from 200m: http://youtu.be/OV1AjRVFSoI

Sincerely,

Sean
7T

The procedure for requesting a corrected handicap is spelled out in the US contest rules. It does not start "post your complaint on rec.aviation.soaring." Have you contacted the handicap committee?
John Cochrane

On Friday, October 31, 2014 10:21:27 PM UTC-5, John Cochrane wrote:
The procedure for requesting a corrected handicap is spelled out in the US contest rules. It does not start "post your complaint on rec.aviation.soaring." Have you contacted the handicap committee?
John Cochrane

The Handicap Committee has been contacted. Tim McAllister the SSA Handicap Committee, Chair has emailed me that "I will put this issue on the committee's agenda as we head into the winter months and begin to look at outstanding handicap issues." This issue (for me)being the handicap for the LAK 17b FES with both 18 and 15 meter wingspans.
I am waiting for my Flight Manual from the LAK factory which should have polars for both wingspans in it. In the mean time a look at the Idafleig report found here http://www.front-electric-sustainer....A%20FES_en.pdf
is very interesting. The report summery states "The results show a very small increase in aerodynamic drag due to the propeller blades in an
expectable order." However the comparison with and without the propeller blades shown in Figure 9 shows, what looks like to me, a noticeable decrease in the L/D ratios when tested with the propeller blades.*
I am looking forward to taking delivery of my LAK 17b FES this coming spring. I realize that the biggest competitive problem that I will have is not with the glider or the handicap number that the committee assigns, but with its pilot.

DK

I have. But I think a public discussion is also valuable in certain scenarios. There will be a lot of pressure in both directions.