I would like to introduce the DIYD community to my project, the T1000. This is a tandem rotor helicopter based on T-Rex 450 parts, with custom 425mm asymmetrical blades. The initial goal for the project (in 2011) was to have a fpv platform that could fly for over 1/2 hour. I now think we can now achieve a 1+hr flight time with a 1kg payload. This is similar to the twin-rex, and indeed utilizes their TH2 for the moment for servo mixing. Our project differs in many ways from the twin-rex though. First of all, we are using a large diameter thin walled carbon timing shaft through a square carbon torque tube. We also use custom designed 2mm carbon nacell plates, along with our in-house manufactured asymmetrical 425mm blades. The third requirement for us getting 1+hr flight times with this platform is the 18650b battery. Though this drawing only indicates a 45 cell pack, I plan on using a 69 cell, or 3s23p custom Li pack. The orientation of the battery pack, and the landing gear have yet to be determined.
Please post any questions or comments (I will not be offended by negative comments, please be honest)
Comments
Hey Sean, how's the progress coming on this project? I hope it is going well, could you keep us updated....
Simplicity? Yes, absolutely in favor of multirotors. At least, for fixed pitch electric ones.
Security? Eh... I dunno. Maybe in the smaller sizes. Probably not in the larger sizes. Lots of people having trouble making large electric multirotors that are reliable.
Costs? Nope, not at all. I can build a really nice helicopter for less than the price of a nice multirotor.
Accessbility? This goes back to simplicity. Yes, anybody can build and learn to fly a multirotor. Helicotpers are definitely harder to get into.
Well Euan, you may be voluntarily missing this point for the sake of other as important ones : simplicity, security, costs, accessibility, ....These are some of the reasons why I would not venture into the heli world.
Lol - I watched your vid Rob...I knew you'd say that :-)
That was a good vid btw - you should do another, or even a series on the pros and cons (including the sums) on each layout? As a "big disc" X8 flyer, it was good to see that it's not all about masses of lift in a small package and damn the efficiency (which was my design goal, admittedly).
Euan: You are. You and everybody else. ;)
Why do I get the feeling I'm missing a trick by not looking at variable pitch single rotors? :-)
So I see that there is some talk here and there about what it would take to get Arducopter to handle this sort of control scheme. Rob, have you gotten anywhere on it? Or would you care to take a stab at the high level details of how you might go about it?
Yep.
The answer to any rotary aero question is: "It depends".
That's why I try to avoid making overly broad statements. There are not many hard and fast rules. At the end of the day it's all about "What have you done for me lately?"
We can theorize all day long. But all that really matters is what sort of performance your machine can deliver.
That is true, but then again in a fixed pitch system the propeller hover RPM will usually not be the same as optimal motor RPM/load. Brushless motors usually have a narrow window where they reach maximum efficiency.
@John, it's not quite that simple though. You have to consider that a fixed pitch propeller (of given size and disk loading) will be more efficient in a hover than a variable pitch propeller. Most of the blades that we use are in variable pitch are simple straight, fixed profile "slab" things. It is possible to make them more efficient, but they can only ever be efficient in exactly one flight profile, and the more specialized they are, the less efficient they are in other flight conditions.
Also, fixed pitch propellers by nature, always hover at their optimum hover RPM. Variable pitch must always hover at an RPM below their maximum efficiency point.
So it is possible for a smaller fixed pitch propeller to have comparable efficiency to a larger variable pitch system.
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