My aerodynamic experiment

[EAS]

Hmm, I plugged everything in. The Tallon 90s just blinked fast....that's supposed to mean low voltage cutt-off. My battery reads 22.7 volts...like it did when I tested each motor with a servo tester months ago. That is the recommended voltage for long-term storage. I never have charged it. I suppose with ALL hooked up it needs more? So I'll charge it in the morning and see if that does it.

Advice, opinions appreciated!

 

[EAS]

...turns out, it's a good thing it didn't power up. Says in the minimal Tallon literature in red letters, "warning, when using Futaba Transmitter, reverse the throttle. Proceed with Caution".

So I have program the Futaba....I guess with reverse servo in the throttle channel.

 

[EAS]

After a bit of transmitter programming, it powred up fine. One of the EDFs was backward... switched 2 wires. All the controls worked including the nose wheel. I had set the control surface servos to 70%. That was appropriate. They all need to be centered next.

I just barely hit the throttle to check the fan direction.... maybe 3 clicks and it wanted to get off my table with a pretty good lurch, even with a pair of heavy files chocking all wheels. One throttle click is the most you can use without anchoring it down. This surprised me. These pair of 70mm JP Hobby EDFs have a lot of power. Easy to move this 7Lb model....very easy.

I'll give myself a YAY on this.

 

[EAS]

Adjusting and trimming the linkage....today.

So I'm thinking this is a rookie mistake. I knew it when I did it, but.....the nose wheel was restricted to about 19-20 degrees each way. Good enough for the runway for sure, I think. On this model and its size, I made the backbone big enough to sink the servos down into, not much wider. The next bigger version will have a backbone twice as wide...but the nose wheel servo will be in front of this divider anyway.

So this is what the dremel is for.

This upright is not very structural. It only holds the (upper) pin for the foam nose section....and there's plenty of other structure around it

Now I've got 23 degree each way...total 46 degrees. It'll have to do.

None of the other servos required anything but moving the servo arm or sub-triming in the programming.

 

[EAS]

.

My first video, motor spin-up.

I was very pleased to see no vibration or torsional twisting. It's good and strong as I intended during design.

 

[EAS]

How are you controlling yaw? Rudder or differential thrust or none?

I've been asked about this (deviation in the motors causing yaw instability)...when I did my motor spin up, in the video (2 posts up) , I got NO indication of mismatch in motor RPMs. My short test up to 3/4 throttle is not conclusive, but it's a good sign. I was a bit surprised at the lack of any sort of deviation in both the motors...and wing stucture. All solid, smooth, no movement or vibration, like the motors weren't even on.

 

[L Edge]

Are you take video of your flight?

 

[EAS]

Are you take video of your flight?

After I build a wind tunnel and smoke my winglets....maybe, but it's a long way off. I may even build the 2nd version with the improvements I learned, sooner than later. I'm doing R&D. That's my priority.