Hey all. Tomorrow and Monday looking pretty breezy here. I am thinking of trying out the old Gamma 68 (Fwind1?), on my Levitator tomorrow. I have never used this foil before and am not sure where I'd position it. If the i76 is supposed to be in position "B" all the way back in the foil mast track, would I mount the Gamma in "A" position and all the way back in the foil mast track?

I had to check with my mate but most of use used the gamma in position C on our wizards (box not track). So I definitely would not use A.

As you have the track you could probably get away with B and push it all the way forward, but most of us used C beyond the learning stage.

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thedoor said..
I had to check with my mate but most of use used the gamma in position C on our wizards (box not track). So I definitely would not use A.

As you have the track you could probably get away with B and push it all the way forward, but most of us used C beyond the learning stage.

I was under the impression from Wyatt at Slingshot that smaller foils were positioned further back in the foil track. Did I misunderstand him? My i99 is a few an inch or so more forward of my i84 and from what I understand, the i76 would be further behind the i84.

I think you would be surprised that the Infinity 76/S42 and the Gamma 68/S42 have pretty much the same neutral points. Thus I would suggest mounting them in the same location. Please post your results, it would be nice to know the value of these "calculated numbers".


Disclaimer: These numbers are based on a 1930's rule of thumb for designing general aviation aircraft stabilizer size. The Reynolds numbers of these aircraft and today's foils operate at are very similar.

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excav8ter said..

thedoor said..
I had to check with my mate but most of use used the gamma in position C on our wizards (box not track). So I definitely would not use A.

As you have the track you could probably get away with B and push it all the way forward, but most of us used C beyond the learning stage.

I was under the impression from Wyatt at Slingshot that smaller foils were positioned further back in the foil track. Did I misunderstand him? My i99 is a few an inch or so more forward of my i84 and from what I understand, the i76 would be further behind the i84.

I believe this is correct if the smaller foil is faster. My point was just that most people needed to have the gamma in C position to get enough lift, whereas the 76 needed to be in B position, so Lake Effect is probably correct. Both of them (gamma in C, 76 in B) should be positioned about 3-5 inches further back than the 99. If you had the gamma in B you could move it further forward in the box to compensate.

Do you have the infinity 76? If your original premise is that the i76 in B needs to be all the way back in the box, then you will likely find that the gamma in C should be all the way back in the box. I have not tried either.

@ lake effect in that table is the gamma in B or C?

The table gives the neutral point referenced from the leading edge at the wing root of the G68 or I76. It doesn't take into consideration whether the foil mast is located in the b or c position on the fuselage. Its summer for us, go out and try them. Leave the analysis for the sub freezing winter days. However this is the input to the neutral point spreadsheet. You can see the I76 had a tail arm of 85.4 cm and the G68 has a tail arm of 78 cm, but the neutral point from the leading edge is the same.

I was able to try an Infinity 76 yesterday. VERY different feeling from my i84. I immediately noticed it's much more loose and definitely faster over all. I only made a few passes with it as the wind was so gusty and the lulls were really light. I had the i76 almost all the way back in the foil mast track. Probably should have been one inch forward for a little better early lift. Happy I got to try it, but will probably not buy one right away. I like the i84 too much right now.

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excav8ter said..
I was able to try an Infinity 76 yesterday. VERY different feeling from my i84. I immediately noticed it's much more loose and definitely faster over all. I only made a few passes with it as the wind was so gusty and the lulls were really light. I had the i76 almost all the way back in the foil mast track. Probably should have been one inch forward for a little better early lift. Happy I got to try it, but will probably not buy one right away. I like the i84 too much right now.

How much further back relative to the 84 would you put the 76? How much do you weigh?

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thedoor said..

excav8ter said..
I was able to try an Infinity 76 yesterday. VERY different feeling from my i84. I immediately noticed it's much more loose and definitely faster over all. I only made a few passes with it as the wind was so gusty and the lulls were really light. I had the i76 almost all the way back in the foil mast track. Probably should have been one inch forward for a little better early lift. Happy I got to try it, but will probably not buy one right away. I like the i84 too much right now.

How much further back relative to the 84 would you put the 76? How much do you weigh?

I put the foil mast 1 inch forward from the back of the foil track.
I weigh 222lbs. Wind conditions probably were not the best for trying it out, due to it being so gusty.