Finally I got my T-Rex 600 in the air.

Equipped with: APM 2.5  - Radio 915 Mhz

GPS uBlox - Sonar-EZ0  -  AttoPilot

RC:  Spectrum DX8

 

I managed to fit the APM 2.5 and the DX8 receiver into one box, keeps the wiring down and adds weight to the box which is better for vibration dampening.

The box is supported by 4 ear plugs acting as great vibrations damper. It works very well, you can’t feel any vibes.

I run 2 BEC’s on a 2200 3S LiPo, one powering the servos, and the second the avionics.

A switch for the avionics and a connector acting as a switch for the ESC makes it easy to get ready for takeoff.  Everything is done; you don’t have to fiddle around, just flick the switch, and let the APM get ready, then push that connecter in, and go.

The Heli is powered by 5000 12S LiPo (2 6S in series), which will give me about 15min+ in the air. I provided for a second set 5000 12S LiPo’s to be connected in parallel to the standard battery pack by a connecter, this will give me a capacity of 10000 12S.

Don’t be afraid to connect LiPo’s parallel; if you do it right there is no harm to you and the LiPo’s.

See link’s    LiPo parallel charging  1      LiPo parallel charging  2

This setup might give me about 25min in the air, and if I fit the Heli with asymmetrical rotor blades,

I might get 45min airtime.  

I think this Heli wil be a great platform for FPV flying, which I will look into in the very near future, after gathering more experience with this setup.

The first flights proofed already very stable in Stab and AltHold, and I was 15min+ nonstop in the air. The average current draw is just 15Amp.

 

My RX setup with Spectrum TX8 is surely unusual; I fly the Heli in Airplane mode.

Flying with an autopilot you don’t need swash mixing or the link between throttle and collective.  You have a flat throttle curve anyway.

I linked the Knob to Aux1 which is my throttle and the throttle curve from the Airplane is my pitch curve. The rest is pretty much the same as you have it in Heli mode.

The pros of this are:

  • In AltHold you can take the collective stick slowly way back until the Heli starts descending, without cutting in to the descending part of the throttle curve and interfering with the motor speed.
  • You can adjust the rotor speed during flight (compensate for voltage drop).
  • You can’t accidentally kick the stick forward and start the motor on the ground.
  • If 1 of the 3 pitch servos gets stuck, you have much more a change to land the heli undamaged, just leave the collective and adjust the motor speed slowly so the heli will descend.

 

It works and flies very well for me.

You could control the throttle with the Knop in Heli mode as well, but you have to sacrifice 1 RC channel, because in Heli mode the pitch and throttle are always linked.

I’ll keep you up to date with my experiences and further developments.

Views: 5731

Comment by Vadzim Chareuka on January 2, 2013 at 7:33am

I have a GPS receiver is not installed as far away as you and have no problem with the quality of the signal! 0,6 HDOP

Comment by Vadzim Chareuka on January 2, 2013 at 7:36am

And I put a tail on the biggest obstacle for the entire electronics! This place is the furthest from the RC-rx.

tail -  video TX-1200mhz 1W

Comment by Vadzim Chareuka on January 2, 2013 at 8:06am

Comment by Rob_Lefebvre on January 2, 2013 at 8:17am

Looking good Manfred.

I really should do a write up on my helis.  I just upgraded my 450 with some more Tarot parts.  It's looking pretty good.

What are the details on your landing gear?

That's one thing I want to figure out yet, is some sort of float system.  I end up flying over water sometime, and I would like to have floatation.  I have seen the inflatable floats for helis, but I don't want something inflatable like that, because I think they'd rupture on a water crash-landing.  I'd like to come up with some kind of rigid floats, but still lightweight.  I was thinking of making them out of foam, with a fiberglass skin.  

I also have my GPS under the main blade system with no issues.

Comment by Josh Potter on January 2, 2013 at 11:01am

Excellent write up.  Question, why did you opt for throttle curves instead of governor mode?

Comment by Manfred Dickgiesser on January 2, 2013 at 12:07pm

@Majid

This are just my estimates of about 45min+ if you use a similar setup; 10000 12S LiPo and asymmetrical rotor blades.

@Vadizim

Looking great your helis

About the GPS location: There where issues with the old MediaTek, but the uBlox might have no problems under the rotor.

@Robert

My “floats” surely don’t float; just keeps the heli more stable and higher on the ground.

I used this Pool Noodles.

I looked around for decent floats, but could not find anything except those inflatable ones, and I had no passion yet to build a rigid one.

@Josh

I use at the moment only the pitch curve and my throttle is the Knob. I had bad experiences with governor mode, causing too much vibrations and tail wag.

Comment by captaingeek on January 2, 2013 at 1:34pm

very nice work!! clean job.

Comment by AVS on January 2, 2013 at 3:06pm

Wow, that is tidy. The entire wiring system is perfect!

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