OK, here’s a picture of my 9m with 4 struts removed, not very colourful, black & grey kite, on a cloudy day, but typical coastal BC fall windy weather. The day was pretty windy, maybe 18 - 25 knots and about 17 deg. C.
The wingtip trailing-edge flutter ( red circled area in the photo ) on the 9m was pretty intense - maybe becasue this kite has the most hours on it and the canopy is a little stretched out. Unless the kite is sheeted in at or near full power, the Trailing Edge that extends beyond a line drawn from wingtip to the remaining outside strut is flapping ( both sides if the kite is at/near zenith ) or lower side near the edge of the wind window.
I haven’t ridden the 9m yet to say how much of a difference it makes. On land, obviously the kite is much lighter, so I expect this mod to help on the low end.
I may try something similar to my 7m, removing just three struts, the three that remain in this pic - depends on the weather, if it blows then my free time will be spent riding, no wind and I’m chopping up my old kites ...
If you want the full details on how to do this mod, then post a request here. If there is interest, I’ll do a write-up of what’s involved.
Have sewn a 15-inch fiberglass tube batten ( from a hobby shop, about 3/8-inch diameter, thin, light , stiff ) on the wingtips where that outer strut was located and all the flapping is happening - will see if this stops the flutter without adding as much weight as an inflatable strut.
Bingo - had the 9m out this afternoon for a quick session, well powered at first, then backing off a bit to just nicely powered, and not a flutter or flap from the trailing edge of the wingtips, Worked really well, this 3/7th mod of the 9m makes it drift nicely when riding downwind with the kite low, all around a more nimble kite. Kind of slants me to do a similar -4 strut mod to my 7m and add battens, see how much wind or calm we get in the next while ....