Hey everyone, Here is something cool that I have been working on that I think you may enjoy.
So, I had been pondering how to make an inexpensive variable prop. I was thinking about using a heli head from a hk450 or perhaps a tail rotor. I eventually saw a post here, on diydrones, where a guy was using a tail rotor from a HK500 (can't find post). I got inspired and found a HK600 tail rotor has the same shaft diameter as the turnigy G10 I use on the techpod. this is what I have come up with.
I measured 15 degree max forward pitch and 12 degree reverse pitch. at 15 degrees forward pitch it drew 40 amps from a 3 cell lipo and puts out just under 5 lbs thrust.
I got the blades here and the tail rotor assembly here. I removed one side of the tail rotor plates and replaced both the shaft in the tail rotor and the shaft in the motor with one long 5 mm shaft. I had to notch it a few times for the set screws.I then made a plate to help support the rotor plate so I could then brace it with some 4-40 all thread rod and nyloc nutsI also made a custom motor mount for the techpod.
After the motor was secured, I cut out a mount for the pitch servo. Then I cut a hole in the foam so I could attach the servo mount to the techpods rear fuselage brace. I grabbed a bell crank from the local hobby shop and mounted it to the rear brace as well.
I have the techpod mostly assembled and should have the batteries for it later today. I hope to be able to start test flying over the weekend. If everything works out well, I plane on offering this as an mod kit for the techpod.
Check out this and the latest techpod news at Hobbyuav.com
Comments
I've done some tests with reversible SimonK ESCs on standard motors and modified props on my multicopters for 3D flying. I'd say, you can do that and it would be simpler and more effective.
@Wayne There sure is nothing wrong with experimenting. but I doubt it will be easy to gain an advantage over other means like a fishnet or simple belly landing which usually is very short-field anyway.
Someone said: "Why think, when you can do the experiment". I love that kind of philosophy. Many inventions have emanated from experiments that proved preconceived ideas wrong.
But my preconceived, know-it-all, grumpy-old-fart thinking is that you will gain very little to the cost of added weight, less effective prop and the lower KISS factor.
Bjorn's law (which I just invented ) says that failure risk increases with the complexity of the mechanism by this formula: (# of parts * # of screws* # of joints)^2
But, for heavens sake, don't listen to me. Do the experiment. Most important: you will learn from it. Also, it will be interesting and fun and you may even prove me wrong. :D
I want so see this thing in action with a full reverse upon landing!
@Bjorn,
Q: What is the problem you want to solve with this solution?
A: well, I am looking to improve performance and reduce landing area needs. The techpod is a slick airplane and being able to hit the breaks could come in handy when flying out of a small area could be very useful.
@brian,
cool design but its only a 8 inch prop
http://www.hobbypartz.com/88e-a28m-bjxt032-evp-combo.html
Cool :D
What is the problem you want to solve with this solution?
FWIW, I have replaced the shaft on one motor with carbon fibre tube. Worked out fine for what I was doing.
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