Customer asks a good prop question with implications…..

Hi Dave,

Quick question about the APC props. I note that for multi-rotor the sizes seem to be with 4.5 pitch. Is there a reason why I should not use say, 9×6 with 9x6R for multi rotor craft?

Thanks
David

Answer:
Hovering props or props that produce best thrust in static air tend to be pitched about 1/2 of diameter or less. As you add more pitch, they can fly faster, but have less bite in static air. They can actually be stalled and have less lifting force until the prop gets to moving forward. This is also why props which are the same otherwise make more noise with lots of pitch. Initially they are stalled or partially stalled. So, if you need more prop than a 9-4 to apply the power to the air you have available in your system, you go to 10-4, not a 9-6. Certainly a 9-7 would be such a bad choice as to be worthless.

All this is considering the model is essentially hovering all the time. Even forward flight isn’t quite as forward as an airplane. Other types of flying and machines can have other considerations that make higher pitch (relative to diameter) correct but this is unlikely in all multi-rotors except maybe a racer.

What we call these props is 1/2 square. Meaning pitch is about 1/2 the diameter. A pattern aircraft or war bird might use a 3/4 square (like a 10-7 or 11-8) or even a square prop (like 12-12) because hovering is not a required and speed is more desirable. These setups are poor on hole shot, but once they get moving they really go.

Dave
Hi Dave,

Quick question about the APC props. I note that for multi-rotor the sizes seem to be with 4.5 pitch. Is there a reason why I should not use say, 9×6 with 9x6R for multi rotor craft?

Thanks
David

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Excellent Joe Nall 2013 Video

Check out this fantastic workmanship. In this video you’ll find every reason why you need to get yourself to Triple Tree at least once. Don’t miss out.

Notes from the author of the video:
The Joe Nall Fly-In, which is hosted by the very generous Pat Hartness at his estate in Woodruff South Carolina is possibly the largest radio controlled model aircraft event found anywhere on the planet. And as a model aviation enthusiast I am captivated by the thousands of beautiful aircraft and have great admiration for the piloting skill of those who travel to the event from all over the world.

But for me it is the event itself which keeps drawing me back and each time I drive through the magnificent front gates at Triple Tree Aerodrome I soon forget about the twelve hour journey it took to get there. You see, for seven days in May each year, the Joe Nall Fly-In is our little slice of heaven on earth that we call home. A magical place where people of vastly different ages, religions, occupations, and wealth come together for a common cause and to forget about the stresses of life.

I could have easily filled my slideshow with pretty photos of model airplanes but in doing so I would have done a great disservice to those who have never experienced Joe Nall. Hopefully you will be inspired by my video and perhaps you could join our family next year.

Stan
Buy “You Raise Me Up” on

Comments from Dave:
OK, you all know me, I can’t help myself. I have to put up resistance to the Objectors to Liberty wherever they reside. The fact that you or I couldn’t offer to pay this film maker even $1 to get those aerial shots for us is an Objection to Liberty. What’s wrong with Liberty I ask you? As a society, we need to identify these people who want to control and hamstring us as what they are. There are forces at this very moment attempting to prevent the very video you just enjoyed along with other activities in our hobby. Let us reject their ideology of control and force wherever we see it. Let us reject the Objectors to Liberty. If successful, at the very least, we’ll have more great video’s of our country’s best events!!!!

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Curtiss-Wright VZ-7

Curtiss-Wright VZ-7Any time you think what you seen in your world experience is new, you should probably sit back and think again. Few things are new. Most things are just repeated visits to old idea’s. Sometimes the technology has changed making something simpler or better.

The VZ-7 flew from 1958 to 1960, however it failed to meet with Army standards and was returned to the the company. Apparently you can see this machine at the the Fort Rucker United States Army Aviation Museum.

I wonder when the description “Quad-Copter” was coined?

Wiki page on: Curtiss-Wright VZ-7

Another blog artical with more information on this subject: Strange Vehicles: Curtiss-Wright VZ-7

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RadicalCast #002

Cast topics, What’s going on at the shop – Multi Rotor Aircraft, Understanding voltage ratings of servos/ignition systems and “Nominal” voltage specifications.  How to tame those bouncy landings and we begin a series about understanding electric power motor systems, important concepts are covered. 

Show notes: KK Multicopter boards.

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Stinger Quad Copter Test Flying Today

Did a flight test on the soon to be released Stinger Quad Copter.  However, I failed to properly secure a set screw, losing a motor on a Quad copter is a problem.   After airing it off (landed in a puddle) I’ll wait for it to dry completly and remount the motor.  More flying Wednesday.

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