Help Need With Spiining Load

[Phil Croucher]

Hi guys - we have this thing that is OK when loaded but spins like mad otherwise - aside from putting a mesh in at the front (there is one at the back), which I have already mentioned, does anyone else have any ideas?

 

 

cheers

 

Phil

[Bladestrike]

Tie a tree to it.

[407 Driver]

Fins ! You gotta have Fins...just like a Simplex or Isolaire seeder...or a Cessna 337 push/pull.

 

Please send me $500 for the Consulting fees

[Randy_G]

Fins ?? You mean like a 1950's, 60's Caddylac ???

Now you know why them things were so stable in the yaw axis.

 

Cheers

[Blackmac]

Two sixty MPH windsocks, one on each corner.

[Rotorhead]

In the past with similar loads I have had pretty good luck with making the lines on the leading end a bit longer. It may not take much, but could make a difference. But definitely, 407 Driver's fins will make all the difference in the world.

 

RH

[Outwest]

Rotorhead is on the right track. This whole spinning load problem was explained to me many years ago by a aerodynamic engineer. Of course most of it was greek, but the jist was that it all had to do with mass. What happens is that when it is empty and with forward speed the load swings aft. The mass shifts and then wants to swap ends. When that happens the mass shifts and it starts it all over again. 407's solution will work, but what will happen is that the fins will have to be of sufficient size and have sufficent arm to counter act the effect. Akin to a tail rotor, you don't solve the problem, you just work against it. Changing the cable lengths will solve it. Of course then it will not fly level when full, which may be unacceptable.

Cheers

[Rotorhead]

I first discovered this when flying snowmobiles around a drill camp. My old buddy, Darrel Adzich, told me that if the straps are longer on the ski mount than the ones on the aft bracket, it would fly into wind at about 45 Knots nicely (without having to remove the windshield). A few years later, I observed another pilot sling a sled in a level scenario and the windshield flew off within an eighth of a mile from departure, due to the spinning expected.

 

This same technique works well with lumber or drill steel too. You can use the same length of straps, just do a double choke on one end and that will change the effective length.

 

RH

[Phil Croucher]

Thanks for that!!

 

Phil

[Rotorhead]

... just do a double choke on one end ...

I re-read that this morning, and I should have said "do an extra choke on one end". Lumber and drill steel should always have at least two wraps when rigging the load with the straps.

 

RH