Beautiful, robmoney! Now you've got to try the GWS direct drive tail motor (no offense Heli-harry but it works better than a dual tail motor and weighs less).
Nice work HH but that g-10 circuit board material is hell on tooling. Eats end mills and drill bits fast.
I made a fin out of styrene plastic sheet (Plastrut material at the LHS) and o-ringed it to the boom and the stock tail support rod. Weighs amost nothing and relies on the rod for strength. It's a lot uglier than HH's.
See:

Uh oh, it looks like I got my receiver in upside down. Maybe that's why it flies better backwards...
No, wait...

I like the Silver....

I think I may have to paint my fin.

The Gyro will make a big differance.

Just a quick question.

Does the dual tail motor actually improve the tail performance, or just the life of the tail motor?

Both

I first went to duals for motor life after burning out a tail motor.

But when I installed the dual motors I found that it really improved the tail response.

I have a HH Gyro and I would say that with A HH Gyro Dual tail motors are a must.

Have fun

Try the GWS direct drive motor--it's way lighter than the dual motor system and works much better. Just flew off a 1320 mAh pack to confirm it. Much better tail holding response than the dual motors (Eflite G90 gyro).
And you don't have to stull a bunch of lead up in the nose to balance it.

?????

Just move the battery forward

Thank you

Yes it does tear up normal bits quick, the bits I have are made to cut this so they hold up ok.

I almost went to a DD tail, but the duals were much simpler (parts available at the LHS etc.) with a HH gyro my tail holds great. I went to the fin as I found it helped when I flew outside.

I never really planned on selling these but after some prodding I made some up.

Though this may be the last batch I make of them.

Yup, mee too I went to dual motors after a stock motor went south. Looked at HH's nice photos of his beautiful mount and made one up to identical dimensions--took me about 2 hours in the machine shop, so I figure it's a hundred dollar part . Worked much better with my g90 but the system was noisy and heavy and still left something to be desired performance-wise (2 or 3 ratchets back and forth before the tail would settle down after hard rudder inputs) and you still always strike the darn rotor on the floor.
So I decided to try the direct drive system. It definitely flies much better and the prop is shorter so you don't strike the floor all the time. I can even operate off my short-pile carpet now. Also much quieter. Sounds like an angry mosquito is chasing your heli.
And I found the parts hanging on the rack at the LHS.
There is a downside though.
I tested all three systems for weight, and current draw at the same thrust (as close as I could hold it to about 50 grams--way more than you'll ever need in flight) in the lab today. They say a picture is worth a thousand words, so here's seven thousand words:

Looks like the order got mixed up so from left to right the above pix are Weight of Stock system, Weight of Dual system, Weight of DD system, Dual system draw at 55.7 g thrust, Dual system draw at 52.9 g thrust, DD system draw at 55.18 g thrust, Stock system at 52 g thrust.

I was surprised at how much current the DD motor drew. But remember, 50+ grams of thrust on the tailrotor--that would give you a piro rate like an eggbeater or something.

I just couldn't hold everything stable at a more realistic tail thust like 5 grams.

THe Fluke meter reads in milliamps, the scale is in grams to the nearest hundreth, and yes I zeroed the scale (tared) before I turned the motor on, so you aren't seeing the weight of the tail, just the thrust from the prop.

So you can in fact expect a somewhat shorter battery life from the DD system.
For me this is sort of a relief!

Actually mine flies so much better with this system (a 1320 mAh battery balances it perfectly) that I don't even notice the time.

Oh yeah newcomers may not know that Heli-Harry got me and my BCPP/Spektrum system flying in the first place. I couldn't fly it with the stock TX (_I_ was way too twitchy) and HH helped me get the Spektrum system set up in my BCPP. Thanks again HH! Aviators rule.

You spent more time testing this than I did conceiving it

I did a bunch of reading as I was first concerned about just keeping the motor from burning out.

I was going to use a Zener and a resistor (I still have the parts), but I did not like that solution. I thought about DD but what I read lead me away from that as it did not seem better than the duals. Brush-less tail, hmmmmm, I could not find a motor I liked, plus I did not want the expense as I knew I was going to the T-Rex. I settled on Dual motors, as they seemed the most bang for the buck.

But the system I really like the best thought is a shaft drive tail, that gets power from the main. My son has that on a Walkera.

So my next project (since my T-Rex is up and running) might be a heli with a shaft drive tail. I'm thinking brush-less on the main and a shaft driven tail.

Or just go to a NOTAR system (No TAil Rotor).

Have fun!

Interesting concept of dual motors. I'm no engineer but what effect does it have on power consumption? PLUS>>>in order for the tail to be held at a specfic position, there must be a given RPM on the tail rotor, be it one motor or two...the tail rotor has to operate at a given speed to maintain a position or positions as input from the transmitter dictates. If it works the way you say, it splits the power consumption between the two motors reducing milli amp draw to each motor in half as opposed to having one motor do all the work still operating at the same RPM. The tail rotor is the "load" in the amount of air it grabs and pushes (resistance to torque from the motor/motors). I guess my point is that if you connect two 500hp engines together...you still only get 500hp. Since motors are not batteries, you cannot put them in series and gain power. If you wire them in parallel, I believe that you are putting the same current and torque to each motor but the load factor is still a constant and power consumption will increase because of the second motor drawing. Check this on meter or scope and see what you get....I'd be interested to see the results. Not that it's not a bad idea in theory and I'm not flaming you or anything...just wondering.

Read the post by Jellyson, as he did the lab work on this (for the current draw).

If you Parallel the motors you actually have twice the available torque but since the load is the same the load per motor is halved.

I fly with the stock 800 milliamp batteries and have not noticed a difference in flight time.

Since were using a variable speed Tail motor and not a variable pitch Tail rotor (like in a T-Rex) you want the motor to speed up quick and slow down quick as well (no flywheel effect).

I think that the dual motors meet this requirement nicely.

In flight I found the dual motors hold the tail much better that the stock single motor I would conclude that this is due to the Increased available torque for the spin-up and the Increased drag for the spin-down.

Have fun.

Yup, the one condition that I didn't test but should have is the Dual tail motor with one failed. After all with two motors you have twice the chance of a failure on any given flight [&o]
I suspect the draw would go way up and might hurt the 3-in-1 (or blow the fuse).
But at least you should be able to choose your crash location.
I will test this when I have a chance--watch the thread.

Harry/Jellyson,

I left the 3 amp tail motor fuse in after installing dual tail motors, I guess this is o.k.???

What do you guys think?

I figure that your crash would be flyable in the event of 1 motor loss when runnig two motors, compared to running just one motor and it failing....

The dual motor system drew a bit over 1 amp at around 55 grams thrust. This is a pretty heavy load, so I don't think that the 3 amp fuse will blow in flight (until it should, i mean). I haven't yet tested the draw of the dual system with one failed, but I now doubt if it would exceed 3 amps. But it probably would blow a 2-amp fuse, as would the DD system.
The DD system draws somewhat over 2 amps at 55 grams thrust. I have no fuse installed, have flown the DD sytem at least 15 battery packs, mostly 1320 mAh, heavy gyro use, everything works copacetic.
The DD motor has much stronger magnets, so it slows down very quickly. The blade is 1/4 the weight of the stock blade, plus there is no gear or shaft/bearings, so it speeds up very quickly. Much better in this regard than the dual motor system.

What is your opinion on a 3 amp on dual motors?

Just want to really protect the 3in1!

See above...

Yes keep the 3 amp fuse

I have yet to blow a tail motor with the dual tail motor setup.

From what I have heard from others who have loast a tail motor in flight with a dual motor setup is that you will notice a reduction in tail authority but is is still flyable.

So unless it shorts out as it dies the fuse should hold.

You could proabably get away with a 4 or 4.5 amp fuse (at your own risk of course).

Might be worth the consideration of installing then.

I am pretty good against crashes anyway, so I would rather be at or under on a fuse instead of being to high and burning up the 3in1.....

We should really get together and just build a better micro heli with all of our knowledge now......

Seems like we have to improve everything on these Baldes.....

Jellyson

Am I reading your results right there is only about a 3 gram difference between the DD and the Duals in force but over double on the current draw.

I can under stand the difference in single to double motor, heating in the windings etc.

But for the DD motor that is substantial.

I'm kinda in that process now, I'd like to build a better blade sized heli one using some of the common but better parts, Super skids, brushless motor (I read on the forums somewhere that you can get a brushless motor and speed controller for under $50.00), dual motor tail, etc.

I have enough spare servos, radios, etc to start on it.

Harry

I will stick with the duals since it is done and is cheap... Seems like a give and take situation unless in hard 3D the DD just keeps up better...

I am not there yet!



Thanks again for the good info guys!