Spin semi symmetrical blades?

[trillian]

Has anyone tried the semi symmetrical Spin blades on a flybarred heli?

I am curious how they perform for FAI type flying where most of
the flight is upright but there is some inverted, how they handle
rolls and loops etc.

They claim longer flight times are possible and I'm curious about this.

[robgt]

This was discussed recently on talkheli.

Semi-symetrical Blades

Cheers,
Rob

[Asid]

I have tried the semi on a flybarred machine. I did sports flying. This was on a 6HV. I got to 13 mins without doing anything but changing the gov. I have a buddy that got 18mins with the same blades on a fbl 6hv.

[trillian]

I have tried the semi on a flybarred machine. I did sports flying. This was on a 6HV. I got to 13 mins without doing anything but changing the gov. I have a buddy that got 18mins with the same blades on a fbl 6hv.

Interesting. What was your flight time before with typical symetrical carbon blades?

[Asid]

Interesting. What was your flight time before with typical symetrical carbon blades?

Changed 2 things:
Gov to 40% from 80% (kontronik end point calibrated)
615mm sym original blades changed to 620mm semi spins
5:30 orig flight times...12 (approx) new times

same flight style...mild 3d/sports

The kontronik accepted this low setting.

Add a pinion change into the equation for better results

[marky]

Yes, I have tried a set on my Raptor, had been using std BBT's up until then. I am very pleased with them, heli feels more stable and predictable. A little bit more pop on the way up and feels a bit more floaty on the way down if that makes any sense.

I am not a 3D merchant so they will be resigned to circuits and possibly loops and rolls.

[Stuart]

Sports flying and mild 3d will work to a degree but I wouldn't get too carried away with inverted having seen a set of spins the chord was some 1.5cm wider than std blades and lift I would be significantly less if inverted than stds. Though in the normal flight you'd get a serious increase in lift...

[Steve]

Presumably with semi-symetrical blades, you will be generating lift even at zero degrees pitch, so you will most likely have to reduce pitch ranges which will reduce drag and increase flight time and power available.

[trillian]

Presumably with semi-symetrical blades, you will be generating lift even at zero degrees pitch, so you will most likely have to reduce pitch ranges which will reduce drag and increase flight time and power available.

That seems to be the jist of their sales copy about them. Presumably you could reduce the positive pitch range
but maybe keep the negative pitch range the same and the theory being that if you're flying mostly
upright you're not paying the price in drag to have equal performance in both directions.

[Asid]

The semis are:
biased toward upright flight
Can be negatively affected by wind more
The blade is creating lift at less degrees (zero)
Reduced HS is used so longer flight times
More forward speed can be generated
Autos Hang time is longer (as they produce more lift)
Heres my thinking...remember my thinking to get the most out of the blades you can consider


Semi-symmetrical blades setup requirement is biased towards a non-linear pitch setup on the pitch

Symmetrical blades setup requirement is biased towards a linear pitch setup on the pitch.