Last updated on July/23/13:

May 25/2013:
Well over the last few weeks parts have been arriving and I have almost completed my build. This project was inspired by another fellow 9116 forum member - Laidback_racer (LBR). He has a version that is completed and is in the process of fine tuning it and it looks very promising.

A DDVP has been used on many other helis including the 450 heli but had never been done with the 9116.

Why would we want to do this with a 9116? Well that's because we really like our 9116 for it's ruggedness but don't necessarily like the electronics that comes with it. With regards to why go with a DDVP setup, we have tried running a non DDVP brushless tail motor setup and the tail blow outs. We (both myself and LBR) wanted much better control over the tail and did not want to go with a belt setup as this would be too complicated for this heli.

Here are the parts that I have used on this build.

9116 frame
BenMa E-1003 main blades
Walkera V200D01 metal swash & swashplate linkages
ZR Z101 head, hollow pipe & balance bar
HK 250GT metal flybar control arm
HK 250GT linkage rods
Turnigy 1440a servos
9x receiver
Trex 250 4800kv 2s brushless outrunner main motor with a Turnigy Plush 12a esc
C10 2100 kv brushless outrunner tail motor with a Turnigy Plush 6a esc
Tarot GY550 gyro (from my 450 project)
MKS DS480 - digital tail servo (from my 450 project)
HK 250 GT metail tail holder, tail grips, tail rotor, tail rotor control...Continue Reading

Last updated on May 25 2013:

I have ordered all of the parts needed to do a brushless motor setup on the 9116.

I have 2 brushless main motors on order – one of them is an inrunner and the other is an outrunner.

The inrunner dimensions are 20 mm in dia and 40 mm in length with a weight of 63 grams. The motor is a 4,800 kV motor that requires a 25A esc (but you can get away with a much smaller esc since this motor does not work very hard in the 9116). Power rating for 3S is 220W but I will be running it on 2S.

The outrunner dimensions are 26 mm in dia and 22 mm in length with a weight of 29 grams. The motor is a 4,800 kV motor that requires a 20A esc (I'm currently running this motor in my 9116 with a 12A esc). Power rating for 2S is 150W.

Just to give you an idea, the stock oem motor weighs about 32 grs and puts out about 38W. I anticipate that I will have to limit throttle to a max of 85% in order to keep the head speed down with an 8T pinion using the 9116 main gear.

I plan on testing the 2040 inrunner first because it should fit between the frame rails with just a small modification (i.e. widen the frame rails on each side by about 80 thousands of an inch). The main drawback for this motor is the weight but I will be adding additional weight behind the main vertical shaft (i.e. 2 ESC’s and a gyro) that should offset this weight.

For the tail motor I plan on using a 1230 brushless inrunner that weighs a few grams less than the current HB CP3 DD...Continue Reading

Today I did a test to see what the temperature my tail motor and main motor got to after I hovered in place for 4 1/2 minutes. I kept the heli in place in the same spot during the whole period.

I'm running a 9116 OEM main motor and a Honey Bee CP3 DD tail motor and rotor.

Here are the links to the Honey Bee parts that I used but I understand that they are slightly cheaper at Banggood.

http://www.rc711.com/shop/tail-motor...ath=166_22_156

http://www.rc711.com/shop/tail-blade...ath=166_22_156

The outdoor temperature was 55F (13C) and the tail motor temperature after hovering for 4 1/2 minutes was only 95F (35C) - it was just warm to the touch.

The main motor temperature was much warmer at 155F (68C).

With my watt meter the tail motor was drawing 8 watts at max rpm.

I ordered a head from the BenMa E-1003 which is a heli of similar size to the 9116 because it was reported that it was a good replacement head. The head cost $1.00 from Bangood and I purchased 3 of them for $2.34 - thats 78 cents each!

The install of the E-1003 head was very straight forward as I was able to use all of my 9116 parts (i.e. 9116 swash, flybar and links). The E-1003 has mixing arms that have a ratio that is approx 1.3-1.4:1 whereas the 9116 mixing arm ratio is 1:1.

The lower link angle is very similar to the 9116 lower link angle.

I'm very happy with how the head works and there was a noticeable difference in how quick the swash moved as compared to the 9116 head/flybar setup.

Here is the link to the video with the E-1003 head. In this video you can see that I had to back off on the forward stick because it was moving forward much faster than with the 9116 head. I believe that this is the to the E-1003 mixing arm ratio.

DH 9116 with BenMa E-1003 head (0 min 43 sec)

It may not be that obvious in the video but I took it outside and I was very happy with the results of the modification.

E-1003 head and 9116 flybar 2 (0 min 43 sec)

...Continue Reading

Since the V912 board was limiting the servo throw, I decided to install a 9x receiver as well as the V912 pcb on the 9116.

The 9x receiver is powered by a UBEC (provides a regulated voltage for the receiver) and the 1440 turnigy servos are plugged into the 9x receiver.

I only used the UBEC because I had purchased it for another project and had it lying around.

If I were to do it again, I would buy a small 6A esc like the one shown below.

https://www.hobbyking.com/hobbyking/s...idProduct=4318

This ESC (as well as most ESC's have a Battery Elimination Circuit aka BEC) can provide power for a receiver as well as the servos. The above ESC can provide 0.8A of regulated power which should be enough and it is almost half the weight at 6 gr instead of 11 gr.

The V912 pcb still controls the the tail motor, gyro and main motor.

Previously with the V912 pcb I had cranked my limits on the 9x Tx up to 125 % and I was not getting enough servo travel. Well, I'm happy to report that I no longer have a lack of servo travel. In fact I have too much servo travel and had to reduce the values down to the 80-90% range.

Here is a video of the servo travel that I now have.

9116 with both V912 and 9x receiver (0 min 21 sec)

Here is a video of the heli indoors.

9116 in flight with 2 receivers (0 min 27 sec)

...Continue Reading

I have been able to use my Turnigy 9x tx on all of my aircraft except I was not able to get it to work properly with the 9116. I could bind to the 9116 but there was a rudder issue where the tail motor was uncontrollable.

The WL Toys V912 pcb is very similar to the 9116 pcb and I read a post from the V912 forum where a user had successfully used the 9x transmitter to control the v912 heli. Laidback_Racer posted that we was able to get the V912 board running in his 9116 so I put the two pieces of information together and proceeded to order a V912 pcb.

I was able to bind the V912 board to the Turnigy 9x and the rudder control issue went away but now I had another problem.

BTW - to bind the 9x to the V912 I have to do the following:
1) power up heli
2) while holding the 9x bind button power up the 9x
3) turn off the 9x
4) turn the 9x back on and the V912 board is bound to the 9x

NOTE: You have to do this every time but it does not take very long and it works every time!

The problem encountered was that I was not able to get enough throw from the servos. I tried everything I could in order to increase the throw on the servos but I determined that the V912 pcb was limiting the servo throw to less than a 90 degree angle.

Here is a link to a video which shows the servo throw on two 9116 helis where one is running the 9116 pcb and the other is running a V912 pcb.

Dh 9116 with V912 pcb bound to 9x (0 min 55 sec)

As you can see, the servo throw on the V912 is limited and this will be addressed in my next post.

Here is a photo of a battery tray that was made from fairly thin gauge aluminum - it could have been thinner gauge but that's what I had.

As you can see, I used the two pcb mounting points to anchor the battery tray at the top and then I drilled 2 more holes to mount the lower part of the tray underneath the heli.

The battery tray has velcro glued to it so that the battery can be anchored to the tray.

In addition to the velcro on the battery and tray I have glued a velcro strap for additional security so that the battery will be firmly held in place.

With the battery mounted on the battery tray as shown, it allows you to protect the PCB by mounting it underneath the battery tray.

By having a battery mount like this, it gives you the added flexibility of positioning the battery so that your heli is balanced front to back.

I used to velcro mount my battery under the canopy and it put quite a bit of weight on the canopy. When I crashed it would take out the plastic canopy stems. After buying a few of these, I decided to make my own. I've stopped mounting my batteries underneath the canopy but here is an easy mod to make which will allow you to quickly remove the canopy.

Attached are some pictures of my canopy stems that I made. I used an old plastic canopy stem as a template and made an aluminum plate with 3 holes (2 for the original mounting screws and 1 for the canopy stem). For the canopy stem I took apart an old 9116 OEM tail rotor and used the shaft for the stem.

My name is Mike and I have 2 of these helis. Have had them since May 2012 and these were my very first 4ch helis. I bought 2 of them because I thought it would be cheaper than buying 1 with a bunch of spare parts. I was so nervous when I first powered the heli up that I had training gear on it and can't remember how many batteries I went through just powering it up but not enough to lift off.

I was so excited when I got the heli off the ground and was somewhat in control of the heli! I crashed this heli many times in my back lane and was surprised at the lack of damage.

I could not venture very far from my home because I had to recharge my battery but since I had 2 of them, I could get about 10 minutes of flying time. I had to come up with a solution to this problem and I purchased 10-800mah lipos and figured out a way to quickly change the batteries at a field. This did not work out very well but it did allow me to take the heli to a larger flying area.

With all my batteries charged, I was ready to go flying the next morning. I headed off to the field with both helis and my 10 batteries when the flying conditions were not so good but I was impatient.

I could not believe how much better this was vs just going up and down my back lane! I got the heli really moving and buried it into the ground. Picked it up, dusted her off, checked for damages and off I went again. This time I got the heli up fairly high and it quickly got very small in the sky. I...Continue Reading