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I think you've misunderstood what a "ground loop" is. It doesn't have anything to do with the fact that the ground goes through a round piece of metal. Also, the since the PDB is transmitting DC current, there is no EMF noise generated. HF or otherwise. Magnetic field yes, EMF noise no...

I have to think this would be pretty bad for your thrust efficiency.

Very interesting that you say that. Check this thread from just two days ago! http://www.helifreak.com/showthread.php?t=432742 These guys are doing this, have established businesses, and even buy insurance for it. The whole thing is very hush-hush. One guy sent me a PM, I won't post it...

So it is just about MoI? I thought there might be more going on, like the longer lever arms made the motors produce less angular rotation for a given control input. It would make their response "softer". That's a good and a bad thing. Good in calm winds, bad in turbulence. However, if all...

Yes, you could do that. If you mounted the motors such that the lower prop just clears the upper motor, you'd be near 40% overlap, and probably would have good efficiency. It's worth checking on a bench test though.

Same shape, totally different concept, however. I don't doubt the 10 times the flex thing however. It's easy to achieve, because the triangular bike frame probably approaches ZERO flex! So it's not hard to be 10 times more than zero. ;) Still, if the goal is just some flex, the same could be...

Ah, OK. I tested that too, and it doesn't seem to make a lot of difference. In fact, I think that is the data I presented in the graph. I did the 30mm spacer test after my good servo tester broke, so again, I didn't present that data. jes, I should link you to a few other really interesting...

I'm not quite following what you are saying. You want to overlap, but have all the motors exactly in the same plane? That would require you to have a drivetrain between all the rotors, to keep the phasing right so the blades don't collide. That then would require variable pitch so that you...

D/L is prop diameter over motor spacing. So for example, my D/L = 1.18 would mean a prop of 330mm and a motor spacing of 280mm. The theory says that somewhere around D/L of 1.2 to 1.3, you may actually achieve thrust efficiency greater than a single motor alone (by about 5%). But this is...

The only real downside I see is that... I understand that some stability is gained with longer arms. Is this true?

kloner, not overlapping just partially, not a full coaxial. There is theory that says that you can overlap up to 40% of the disk area without losing efficiency (which you do with a Coaxial), and I proved it out in testing. I allows you to shrink an octo to a more manageable size. Here's a...

Haha, for a second I thought the second picture was NSFW. ;) The ring idea is interesting. Probably much stiffer than using booms. Going with overlapping blades would shrink the ring down to a much more reasonable size. In fact, you could cut the whole thing out of CF I think. For sure, you...

One question I have, it how much vertical disk seperation is enough? I used 30mm in my test because that's what I had. Could we use less? I haven't seen any disk deflection, ever, on these things, but I can't say it doesn't happen in flight. Something else that might blow your mind: There...

I'm starting this thread in the interested of not further hyjacking this thread: http://www.multirotorforums.com/showthread.php?5825-Hamer-X4-Ultimate-Kopter-for-Filming-Industry Some other photos of my multicopter build are here, if you're interested...

No, this quote is complete BS. Nice fact checking by the journalists. Do any of them do their job anymore? I am having a real hard time getting my head around the laws, but best I can tell, is that it is currently "not legal", and the FAA specifically says it is "not allowed". However, there...

Cloner... you talk about seperation, you mean about between the Vtx and the control Rx? I have a problem with the addition of a telemetry link. So I'm running 900MHz telemetry, 2.4GHz control (with telemetry also!), and 5.8GHz video. So far I am not having any issues with all of this on a...

I tested with an 18% overlap, and showed a much lower amount of efficiency loss than coaxial. Theoretically, you can get up to a 40% overlap before you start to lose efficiency. In fact, the theory (using a whole lot of complicated math) shows that you could actually have *more* thrust with...

I just tested this on the weekend and confirmed the typical numbers of 20-30%. https://docs.google.com/spreadsheet/ccc?key=0AjWH4Q7IAU5YdFRfY2ZxWHdaYlp4cnZPT1pfVGRlLVE#gid=0 D/L 1.18 is a two motors with an 18% blade overlap, staggered by just over 1%. I basically proved out a theory that you...

I think it's about $200, $250? Something like that. Plus options. Telemetry, sonar altimeter, etc. I don't have sonar, can't get it working. The heli is too loud.

Actually, I'm not entirely sure what the headspeed is. I want it at 1800, but the governor sort of sucks. Yes, theoretically it can do missions, but nobody has done it with the heli yet. I'm sort of leading the testing and development of it at this point.