xieda 9958

Someone on RC Groups mentioned that they wanted to use the low cost Xieda 9958 RX board as a replacement for the Solo Pro and Bravo SX boards. Here’s a side by side comparison photo for your modding/brainstorming purposes.

I recently purchased a Turnigy 9x and am in the process of setting up my preferred throttle curves for it. So I figure I’d share.

From my understanding, being able to set your throttle curve is the benefit of setting up the initial profile as a “heli” instead of “acro”.

To get to the throttle curve section of the menu, hold down the menu button. Select Settings. Then select THR/CV.

Currently, I have two different throttle curves link to my [Aux 3] F.Mode switch.

Owners of the 9x will know that the F.Mode switch can be toggle between three settings: N, 1, 2 correlating to Norm, ID1, ID2 in the menu.

Initially, I have a normal, more linear throttle curve set for the N switch position:

But I found that I like to fly with the ID1 position. It has the following curve set:

I think I will make the ID1 settings my Normal in the future. My ID2 position currently has a rudder to elevator mix that I am experimenting with. Being able to quickly switch between different settings in mid flight allows you to do a A:B comparison and makes it easier to find the combination of settings that fits your flying style.

I’ll post more as I complete setting up and fine tuning the Turnigy 9x with the Xieda 9958.

Side note: You notice that the stock 9x firmware gives you the ability to adjust 5 different points on the curve. Similar to the Spektrum family of TX. This is one example of where the custom firmware like Er9x shines. They allow 9 points on the throttle curve. For those who need absolute control. Obviously overkill for a micro heli like the 9958…but it’s one example of the power the Turnigy 9x posses with a custom firmware flash to it.

Fabricated a carbon fiber main shaft for the 9958. Here’s the stock 9958 weight before and after the carbon fiber shaft upgrade.

The stock weight without the battery is above. The carbon fiber upgrade 9958 is the photo below.

The main motor has a lift of about 42g. So shaving a gram off the flight weight will allow the motor to essentially be 7% stronger. So it’s every gram counts with these micro helis!

Top photo is the 9958's stock weight. Bottom photo is with a CF main shaft.

Here’s a video with it flying. Unfortunately the battery was mostly gone by the time I thought of turning on the camera.

A project I have been putting off until tonight. Switched out the aluminum 9958 main shaft to a carbon fiber one to shave off some weight. Just sharing some dimensions in case someone else is thinking of making a carbon fiber main shaft for the Xieda 9958.

Comparision of main shaft between Xieda 9958, Bravo III, modded 9958 CF, Blade mSR

First I took a Bravo III carbon fiber main shaft and drilled a hole at the top (The bottom two holes works out well already). Then I measured 3mm from this hole and simply saw off and discarded the excess at the top. The hole location reflected the location of the top hole on the Blade mSR because I was gonna fit on the Blade mSR head onto my Xieda 9958. Here’s a close up of the Blade mSR main shaft in case anybody else there needs it.

Blade mSR Main Shaft hole location

Another angle of the Blade mSR main shaft

Here is a photo of the Xieda 9958 with Blade mSR head and flybar. As a bonus, if you look closely, you can see that the swashplate hub has a pivot ball like the mSR. I stole the upper hub out of the Trex 100s. I like the idea of the pivot ball and the link balls on is about 16.5mm. Much longer than the Xieda’s stock hub’s ~12.5mm. So more throw.

Xieda 9958 modded with Blade mSR head, blades, flybar

The result of these modifications is that the Xieda 9958 flies really well. In fact, the sliding tendencies the stock 9958 has during bank turns appear to be all but gone. Unfortunately, I made too many modifications at once, so I don’t know which of my changes is responsible for the improved, tighter turns. I will do a follow up post once I figure out if it’s the carbon fiber shaft, the Blade mSR Head, or Trex 100s upper swash hub that is responsible for the improved flight.