rotor diameter

[scottessex]

I am rebuilding my Bensen/KB3 I will be droping the keel and possibly adding a tall tail. I have the opportunity to pick up a set of 25 ft dragon wings from a friend, for a reasonable price. I originally had 23 ft rotorhawks.

Will the 25 footers be too big for a light weight gyro? and if so why? what is going to be the difference, besides they will spin slower. Or am I all confused and just need to buy a new set of 23's from Ernie? :confused:

[rehler]

The concern I would have is the longer blades hitting the ground in back, which will require a taller mast.

This can be serious, as one pilot was killed years ago when he added longer blades which hit the groung at lift off and flipped the gyro over.

[scottessex]

I can make the mast taller, or cut the blades shorter!

[Udi]

Scott,

In addition to the ground clearance problem that Ken has mentioned, you don't want the blades to be too lightly loaded. There are a few problems with blades that are too lightly loaded.

First - they may turn too slowly. This is bad because they would have less inertia and will slow down and flap more quickly.

Second - You will suffer more when flying in unstable air. Flying in gusty winds and thermals may be uncomfortable and even dangerous with a very low disc loading.

Calculate your disc loading by dividing your gross weight by the disc area (Pi-r-squared). A disc loading of less than 1.0 lb/sq-ft is too light. For a comfortable flight in unstable air you want a disc loading of more than 1.2 lb/sq-ft.

Hope this helps.

Udi

[joeheli]

This is a good topic. I was plannig to buy 24' rotorblades I think I will buy rotor hawks. I weight 210 pounds, I have a stock Bensen with pre-rotator the only thing I modify is I install a 8.50 gallon KB's seat tank and it has Mac on it . If I order The 24' will that be a good choise ?. We are talking about 6 more inches on each blades :confused: About the weight factor, aircommand use 24' and 25' on there gyros and I think that scott gyro and mines, weights the same as a aircommand.

[Chuck Irby]

Jose, Scott's all-up weight is real close to 500 pounds, therefore he needs 23 foot blades. Have you weighed your machine? Why would you not want DW's?

[joeheli]

There are to Expecive to ship it to PR! I ask Ernie and he toll me that 23' cost $1450.00. The shipping is $250.00. Then when it gets here I have to pay the State tax (6.6%) $95.70 Total $1795.00. The only way I coud buy it is if some one sales me a use one. I will LOVE to get DW's but is to much.

[joeheli]

Or if Ernie can get me a better price!

[Chuck Irby]

Jose, why would the Rotor Hawks be less? I would be willing to pay more for the DW's, personally. BTW, Screw could sell you his used pair of 23's, then get himself the 24's that he really needs, that is if Scott doesn't get them.

[joeheli]

23' Rotor Hawk cost $995.00 with hub include. plus $170.00 of shipping. 6.6% state tax $65.67 with the gran total of $1230.67

[joeheli]

Chuck I check with the last owner of my gyro and told me that my gyro weight is 250 pound with out the pre rotator and with out mufflers.

[Chuck Irby]

Jose, don't trust what someone told you. Get a pair of bathroom scales, weigh the three wheels that touch the ground, add them up and you'll have it pretty close. Then we can determine what length blades you need.