Tip curling - luffing or arc and cell pressure

[evan]

On older kites you can fiddle with the bridle all you want, but there comes a point the cloth becomes too porous to maintain enough internal pressure to keep the tip open no matter what bridle tuning you try. The higher the aspect ratio of kite (thinner profile, less volume) the earlier this will be a problem.

So do a porosity test first if you have problems like this on an older kite before you try anything beyond simple speed system tuning. And up to you to decide if it is worth it to try to make the kite less porous with a new coating, but most of the time it won't be worth the hassle.
Up to you

[Herman]

I agree with all the points made. I mentioned the Aurora merely out of interest as it was demonstrating what I now regard to be a backstalling curl, but this only happens when you are brutal with the sheeting and it is not a problem. In fact I am very pleased with the way it flys and how airtight the ul cloth is even with magnetic blow offs that I may seal at a later date.

The real subject of the post is a 12m Speed3, which I acquired for secondhand very little money, which I just want to experiment with. It is so porous that it doesn’t need checking, I don’t even have to open the butthole to pack it down. I have no expectations of getting the kite back to any level of performance and I only use it with a bug. Oddly I have found it fun to fly like this, as it is a challenge to keep the tips open whilst the main middle of the kite still provides enough power to get around in a bug. It has also almost completely desensitised me from feeling any alarm or disconcertion when a tip starts acting up.

The objectective, for me, for the purchase and this thread, was to enhance my understanding and that has already been achieved thanks to the above helpful inputs. For completeness I have attached a screenshot regarding pmas, but I don’t think the Speed 3 has them as they don’t seem to be mentioned in the manual, but I will check.

Also for completeness I have attached a drawing that might explain why I also asked about changing the arc to reduce the angle “a” in the drawing to decrease the collapsing load on the cell. I am not surprised that this didn’t get any comment because it is unlikely to be worth the work to change the whole arc unless you are set up to rework prototypes etc.

I would like to believe that I can now recognise what is causing various different scenarios. Hopefully others have enjoyed this thread.

PS If I was set on getting the most performance out of the old Speed, opening up the vents strikes me as a good suggestion but that is not why I bought the kite. I might also have a play with silicone dissolved in white spirit but don’t regard it worth playing with toluene for pu solution.

[Herman]

PMA

[evan]

Speed 3 won't have PMA's, it is a recent invention introduced with the Soul 1. So they exist only on the Soul 1, Soul 2, Sonic 3 and VMG 2

[Herman]

Cell sideways tension affected by angle of attachment.

[Breze]

Speed 3 won't have PMA's, it is a recent invention introduced with the Soul 1. So they exist only on the Soul 1, Soul 2, Sonic 3 and VMG 2

FS started with the PMAs already on the Sonic2 2016

[jakemoore]

Speed 3 won't have PMA's, it is a recent invention introduced with the Soul 1. So they exist only on the Soul 1, Soul 2, Sonic 3 and VMG 2

The 3 gallery Speed 4 DLX 8 and 10 has then but not the speed 4 Lotus. It was not published but mentioned in some foil tuning posts on the forum. When Soul came we discovered what they were.

The PMA concept can be duplicated by tucking the top or bottom skin of the kite but really questionable if worth it on this old kite except for the purpose of learning. Foilholio did give us some knowledge even if difficult to understand some times.

[jakemoore]

If this kites future is a buggy engine:

Yeah, I like resurrecting the old stuff and some of the not so old stuff. Still like arcs best but I have such a blast on other stuff too. If you think my blades are funny you oughtta check out my 5 year old mastair 16 with the leading edge cut open like a blade

[Herman]

I think loco4viento is my kind of guy, as I also get a perverse sort of pleasure from getting fun out of something others would discard as crap - in my case it is probably part of a deep rooted personality disorder.

Putting a few darts in a rib and or canopy is not beyond my capabilities but I won’t be rushing to do it. (I have done this with sails in the past.) Once I have finished playing with the bridle and, maybe, a sealant coating, I have quite high expectations for performance gains from opening up the vents.

Although the Speeds cloth feels like limp tissue paper I also have an old open cell Pansh Legend with similar cloth which flys well enough for a bug and, generally, does not curl or tuck even when underpowered. In both cases the cloth feels totally devoid of coating, not a hint of crispyness and packing both is like handling a damp tissue.