I was able to get 5 flights in today mostly in loiter and it's pretty rock solid. I am curious what it will do with a little wind. 

Here are my params for a Trex 550 stretched to a 700 running 1500 RPMs. 

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looks great!!! 

Id like the 3d files please.

Hi Sean,

Thank you for the param file you had shared last time. It works great with the pixhawk. I had to make very little changes in it to get my 550L dominator flying. I could complete a waypoint mission as well.

But the problem is with the battery. It hardly gives me 4-5 min of mission time. My headspeed is 1400. I want to go on longer missions. I tried to put up 2 x 6s x 5200mah x 25c batteries with Talon 90. But it reduced my flying time to 3 min. I guess the weight of the battery is too high compared to what it can offer.

I had earlier read up Rob Lefebvre's comment that 550 is an inefficient machine unless it is stretched to a 600 or 700. I plan to stretch my 550L dominator to a 700 like you to get 30-40min of flying time. I plan to order the following parts:

Tail boom - 700L size

Torque tube - 700L size (with extra bearing)

Rudder control rod - 700 size

Tail boom supporting braces - 600 size (700 size braces have M4 bolts - not suitable for me)

Tail blades - 105mm

Main blades - align 700mm or 720mm

My questions are:

  1. Do I have to change the rotor head completely for the 700 blades to fit properly? Or is it enough if I just order the main blade holder (would it fit on the stock main rotor head)?
  2. Do I have to elevate the vehicle by changing the landing skid so that the tail blades do not hit the ground?
  3. My motor is BL-730MX (850KV). I am not sure if this stock motor can take the load of the 700 or 720mm blades. Do I need to change the motor too, like you did?
  4. What batteries do you use to get this 35min flight time? Thunderpower 70c ?

Can you please help me out with these questions? Thank you for your time.

- Regards


Rish,  Are you sure about your head speed.  1400 with stock 520 or 550 blades is very low.  You should be able to get close to 10 minutes with a 5 amp pack and stock blades at 1800 ish headspeed. 


David R. Boulanger

Hi David Boulanger,

I had checked up your modification too :) . But I was keen on trying to stretch it to a 700.

I fly with the 550 size blade. I do not practically have any extra payload other than a crossbar and the mounting for the pixhawk. But I suspect that my batteries are not up to it. With new batteries of the same specs I had mentioned in my previous reply, I used to get about 12-15 min on a 550E (flybarred) with 520 size blades at 1400 rpm. But with this dominator (550L) I am not able to replicate that. My battery weighs 800gm.

I programmed Talon 90 for 1400 rpm and measured the rotor HS with the optical rpm measuring tool. http://www.helipal.com/magic-mirror-rotor-head-speed-tachometer.html . I don't have any reason to suspect either of them.

The ambient temperature here is about 40-45 deg centigrade at this time of the year. So, I guess battery performance is effected. Even the motor heats up pretty quick.

- Regards

Hi Sean, I know this is an old post but any chance you could share your 3D printed files for the pixhawk mount and GPS?

Thanks Kyle

Hey Sean, could you share your 3d printer files for the pixhawk mount and GPS mount with me as well. My email address is rkeith3472@gmail.com

Thanks Robert

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