The laboratory has been buzzin' again

[runesb]

When you strech to a 1000 or so, a motor will be to heavy and harder to make the cg when mount it on the tail g.box.
Make a 1.2m bomm and add just the tsil gear you will see that a few grams do a lot with your cg

[nightflyr]

Originally Posted by R_Lefebvre

Ok, so, many of the typical reasons to go with a DD tail. Then why not just put the motor right at the back as well? Are you planning aerobatics with this thing? Making the tail true direct-drive really simplifies things.

The tail assembly is a designed upgrade for 550/600 class birds and hopefully 700 class frame sets.
While also trying to improve on stretching capabilities by avoiding using the stock plastic parts if possible.

This setup is purely for AP, don't believe anyone would attempt aerobatics while carrying camera equipment and swinging 1000 mm ASYM blades.

The designed purpose for the separate tail drive is to compensate for the extremely low HS.

Keep in mind there are not many 1000 class birds flying , so this is for all intent experimental to gain better control, performance and integrity with what is available at present.

[R_Lefebvre]

Originally Posted by runesb

When you strech to a 1000 or so, a motor will be to heavy and harder to make the cg when mount it on the tail g.box.
Make a 1.2m bomm and add just the tsil gear you will see that a few grams do a lot with your cg

If this is for AP as indicated, the CG should not be a problem. Putting the motor on the end of the tail might allow you to move the main batteries off of the boom, and put them back up front which is a much better way to go.

The tail assembly is a designed upgrade for 550/600 class birds and hopefully 700 class frame sets.
While also trying to improve on stretching capabilities by avoiding using the stock plastic parts if possible.

This setup is purely for AP, don't believe anyone would attempt aerobatics while carrying camera equipment and swinging 1000 mm ASYM blades.

The designed purpose for the separate tail drive is to compensate for the extremely low HS.

Keep in mind there are not many 1000 class birds flying , so this is for all intent experimental to gain better control, performance and integrity with what is available at present.

Ok, most of the same reasons I'm trying to do a DD tail as well. But I also want to get rid of all the nasty powertrain bits.

Now, where you have a massive advantage over my approach, is in motor selection. You can take advantage of a small gear reduction ratio, allowing for a higher KV motor. I can't. That's one thing that really sucks about the DD tail, is powering it is tricky.

Currently, I use 2x 4S packs for the main motor (8S), and a 2S pack for the avionics. HV servos direct with no BEC. There's no motor in existence that will spin ~7000 RPM on 8S. And trying to run on 2S would require massive amps to get the power the tail sometimes requires. So I'm kind of stuck. I have two options:

-Change to 3S with a BEC on the avionics, and use 3S on the tail motor which is a little better. About 600 KV motor will do the job.

-Stick with 2S on the avionics, and run the tail motor on 4S by tapping off the first of the main battery packs. This would be OK, except the fact that now one of the 4S packs will always drain faster than the other, which can cause a lot of problems.

Any other ideas?

[R_Lefebvre]

I wonder if this would work to run on 8S:

http://www.hobbyking.com/hobbyking/s...ner_Motor.html

350KV on 8S should give 11760 RPM, correct? But that's at no load. It'll be a little lower with more load? How much might it drop typically?

Then I can run this ESC:

http://www.hobbyking.com/hobbyking/s...ler_OPTO_.html

This has AFW, so you can run it at reduced speed without it blowing up. Run it at 60% governor setting would get me 7000 rpm? Or maybe 70%? Should be totally fine, since I'm already running the main motor at 70% on a Hobbywing ESC and it's totally fine.

Maybe this is the answer. Only thing that sucks is that ESC is $108.

The other thing is that this motor is really only rated for 5S. But I think that the mag wire insulation isn't likely to actually break down at 33V. I think they only really rate them like this because on high Voltage, the potential to draw too much power is there. But if you manage that properly...?

It's rated for 1190 watts, but I don't expect it would ever go over 1000W, and typically would be at 100W.

One of my goals it to eventually get to the point where I have a DD tail, and a single belt reduction drive for the main rotor. No noisy gears or flappy tail belts anywhere in the system.

[nightflyr]

I can not speak for anyone else..

But, I'm running 4 6S 5000 packs for a total of 12S 10,000mA powering the main drive motor along with a 2S 5000mA powering the electronics.

Add to that a solid motor/camera mount holding a Contour, along with a second mount with a GoPro all mounted to the extreme forward position as you can see below.



And I'm still a bit tail heavy...
The hope is to run the smallest motor/ESC combo possible on the tail drive.

At present, I can just barely hold tail control at 760 HS running 180mm tail blades, if Ibreach say 950 HS tail control is much better, but I'm not too thrilled running tail blades that large.

My logic says I should be able to achieve what I need by using a 450 class motor on 3S ( hopefully )

Your specific requirements for what your attempting will be a trial and error process much like mine.

In the end, it all turns out to be an exercise in experimentation and hopefully a working solution.

[R_Lefebvre]

Wow, I can't believe that doesn't balance already. But, you could still move that other battery forward even more.

Anyway, was just wondering what your plans are as it's an unusual arrangement.