New Props? New Motors? TBE on RTH

[PilotHal]

Hello;
I have a F550 with the stock motors and Graupner 8"x5's. I have landing legs, the Zenmuse H3-2D gimbal with a GoPro Hero3, and a 6600mAh Pulse flat pack. The performance is a bit lacking and I'm finding that I am getting a massive toilet bowl effect when the copter comes home to land.

It has been suggested that I:
a) Rotate the GPS mast so that it is inline with magnetic declination for my area (which I don't understand since this is a GPS system). This could be the reason for my TBE.
b) Recalibrate my compass since I did move the GPS antenna to the center of the craft.
c) Install larger props. Perhaps 10"x5's, since the F550 is a lot heavier now than stock.
d) Install larger motors.

I am looking for recommendations on the above items. Thanks!

 

[ProPilotWannaBe]

Hal, I would agree with a, b, and c.
A) the aligning the GPS isn't because of the GPS, but because of the heading sensor in that antenna. When flying forward/backward, the FC is maintaining that heading. So if the rotation is off a little, you don't fly in a straight line. So regardless or not of it being the cause of the TBE, it should be aligned for other operations.
B) the manual says to recalibrate for any changes... Just a good idea in general and easy and quick to do.
C) try the new DJI 1038 props. They are extremely robust and I know several that use those on the F550 fully loaded with Sony NEX and landing gear, etc.
D) All my friends that have the F550 with the GoPro and/or NEX are using the stock motors. So that shouldn't be your problem.

 

[PilotHal]

Cool. Thanks for the information.
I'm a fan of the Graupner props so I think I'm going to try the 10" ones and see if that makes a difference in the flight characteristics.
I'll also recalibrate and rotate the GPS antenna accordingly even if I don't understand why.
Thanks!

 

[ProPilotWannaBe]

LOL... I hear ya. I don't fully understand the reason/benefit for recalibration, so I'm just thankful that it's an easy process.
The antenna alignment I understand only because I design flight control systems.

 

[Phil550]

Hello;
I have a F550 with the stock motors and Graupner 8"x5's. I have landing legs, the Zenmuse H3-2D gimbal with a GoPro Hero3, and a 6600mAh Pulse flat pack. The performance is a bit lacking and I'm finding that I am getting a massive toilet bowl effect when the copter comes home to land.

It has been suggested that I:
a) Rotate the GPS mast so that it is inline with magnetic declination for my area (which I don't understand since this is a GPS system). This could be the reason for my TBE.
b) Recalibrate my compass since I did move the GPS antenna to the center of the craft.
c) Install larger props. Perhaps 10"x5's, since the F550 is a lot heavier now than stock.
d) Install larger motors.

I am looking for recommendations on the above items. Thanks!

If you have moved the GPS then I think you have to alter the GPS Mounting values within Naza Assistant to suit, as well as recalibrating it.
My 550 weighs 2.4kg and works fine with 10" Graupners and Turnigy 5000mah 3S lipos

 

[PilotHal]

LOL... I hear ya. I don't fully understand the reason/benefit for recalibration, so I'm just thankful that it's an easy process.
The antenna alignment I understand only because I design flight control systems.

Then why do you have to align the antenna? I mean it's a GPS system, isn't it? Please explain.

 

[PilotHal]

If you have moved the GPS then I think you have to alter the GPS Mounting values within Naza Assistant to suit, as well as recalibrating it.
My 550 weighs 2.4kg and works fine with 10" Graupners and Turnigy 5000mah 3S lipos

Yes. I did adjust the mounting values in the assistant software to match the new position of the antenna. I need to recalibrate.
I want to put on 10" Graupners. I am using the 6600mAh 4S Pulse flat packs with my F550. IS this a problem?

 

[ProPilotWannaBe]

Then why do you have to align the antenna? I mean it's a GPS system, isn't it? Please explain.

In the systems we design for full size aircraft, having the magnetic heading information helps improve performance. For example, even flying an ILS approach which has ground based signals, having correct heading helps improve that performance.
That being said, it can be overcome by the software design that is used, and I think that is what the new Naza firmware does. One of DJI's claims about the new Naza firmware is that it isn't as susceptible to magnetic variation of the area flow in.

 

[Phil550]

Yes. I did adjust the mounting values in the assistant software to match the new position of the antenna. I need to recalibrate.
I want to put on 10" Graupners. I am using the 6600mAh 4S Pulse flat packs with my F550. IS this a problem?

The general consensus is that you use 8" with 4S and 10" with 3S, but the best compromise is 9" Graupners with 4S. Do a search on the forum and you'll find loads of info on this.
The alignment of the antenna is all to do with magnetic declination which varies across the globe - http://magnetic-declination.com/

 

[PilotHal]

In the systems we design for full size aircraft, having the magnetic heading information helps improve performance. For example, even flying an ILS approach which has ground based signals, having correct heading helps improve that performance.
That being said, it can be overcome by the software design that is used, and I think that is what the new Naza firmware does. One of DJI's claims about the new Naza firmware is that it isn't as susceptible to magnetic variation of the area flow in.

Ok. I too am a GA pilot and have the Garmin G1000 in my aircraft. So I get what you are saying. Thanks! BTW: I fly a Wookong-M in my 550.

 

[PilotHal]

The general consensus is that you use 8" with 4S and 10" with 3S, but the best compromise is 9" Graupners with 4S. Do a search on the forum and you'll find loads of info on this.
The alignment of the antenna is all to do with magnetic declination which varies across the globe - http://magnetic-declination.com/

Yeah, I don't understand the logic of using 3S vs 4S packs. SO I guess I'll go with the Graupner 9" props just to be safe. Thanks!