Sponson down force

[David Bryant]

thanks Gill.

So add a few degrees bend in-ward to the turn-fin?

I'm probably gonna leave spoilers off and test first. I'd rather keep sponson top-surface flat or neutral.

Dave

 

[gil sonsino]

David I would try a new turnfin from David Preusse or Mike Hughes but if you can bend yours its ok.IHonestly I don't think the spolilers will hurt your performance..For the sponsons just follow instructions but with a little toe in .Gill

 

[Ray Sametz]

In the early 80's the Prather Piranha's rigger was built with spoilers in the rear of sponsons...I had one that was a pain in the heck with left turns

Actually I'm building a brand-new Piranha kit as I speak. Gonna use new Picco 45R. I'm begginning to wonder whether to even use the stainless sheet "spoilers" on the sponsons and, instead, just use negative strut angle to neutralize instead? Would think the spoilers are mostly adding drag (and some weight).

Dave, post a pic of Piranha sponsons.

 

[Albert Araujo]

Get rid of that nice round sweep at the top surface. Make the back of the sponson no more than 45 degrees and use a sharp break on top. what you have now is an airfoil that is creating lift.

Albert

 

[David Bryant]

In the early 80's the Prather Piranha's rigger was built with spoilers in the rear of sponsons...I had one that was a pain in the heck with left turns

Actually I'm building a brand-new Piranha kit as I speak. Gonna use new Picco 45R. I'm begginning to wonder whether to even use the stainless sheet "spoilers" on the sponsons and, instead, just use negative strut angle to neutralize instead? Would think the spoilers are mostly adding drag (and some weight).

Dave, post a pic of Piranha sponsons.

I will take some images tommorrow, then post.

 

[David Bryant]

Here are a series of images documenting the Prather Piranha front-right sponson. I tried to capture all pertinent angles. (of course these sponson's are raw and un-finished, the inside edge is not covered)

 

[David Bryant]

A few more Prather Piranha right-front sponson images