FlyingWings Venturi FPV Evo II

[Coyote]

Which motor did you go with Neil ? Was it the Scorpion SII 1100Kv with a 9x7.5 ?

[iPeel]

Which motor did you go with Neil ? Was it the Scorpion SII 1100Kv with a 9x7.5 ?

Yes, but the motor is 1190Kv not 1100. The APC 9x7.5 is a good match and 100A ESC should hopefully take the abuse, I run a 120A JP EnerG Pro and even then I run a northbridge heat sink on it.

http://www.scorpionsystem.com/catalog/aeroplane/motors_1/s-30_v2/SII-3026-1190KV/

[Coyote]

Thanks Neil :)

In your videos it looks like it peaks out at 80 amps, is that about right ?

[iPeel]

Yeah, I think I've seen about 85A on this prop.

[Brucey]

More like you average 80amps!

[Coyote]

Hehehe

"Are you speeding up Neil ? " .........

"Err ........... no......... honestly I'm not :) "

[Coyote]

Crazy isn't it. Scorpion wanted £116 for the SII 3026 1190kv shipped from China to me. Bit steep really but Scorpion are good motors.

Had a quick look around. Same SII 3026 1190kv motor from Robotbirds  here in the UK for £60 first class recorded. Nearly half the price of the actual manufacturers lol.

[Coyote]

I was wondering after watching your maiden the the 13km trip Neil why you swapped from 9x9 to 9x7.5 prop ?

On the maiden the 9x9 was giving you 100 kph for 10 - 15 amps where with the 9x7.5 you were pulling 20 amps just to scrape a 70 kph cruise.

Surely the 9x9 is a lot more efficient for cruising even though its thirsty at max throttle. 

[Coyote]

Mine is all ready for a maiden today !

Neil went with the North Bridge cooling approach for the ESC, I went for a more boy racer approach of a ram air intake :)

The ESC is situated a bit further forward than I hoped but cut the foam out directly above :



Designed a quick and dirty ram air scoop :



Grafted the two together :




And ended up with this :

[Brucey]

Ha, that intake is huge! I used to use half a highlighter pen lid. Hope the air has somewhere to go, the exhaust should be twice the size of the in.

Did you make the wings removable in the end?

[Coyote]

Size matters ! :) :)

Yeah the rear is cut away for the exhaust so should be fine there.

Once the wing arrived unfortunately the height the spars are installed meant I couldn't do it, if they were a fair bit higher I could have, but then you have the spars running through the center of the airframe.

[Brucey]

It's not the size, it's what you do with it!

Ah shame, well it's a manageable size, fits across the back seats ok.

Good luck with the maiden

[Coyote]

Cheers. The maiden was uneventful really. Flew straight off and very minimal trimming required. It was a little twitchy on pitch but flew nice :)

[Brucey]

Good news.

It's amazing how little throw it need on pitch.

[Coyote]

No its not that Brucey.

How I mean is in level flight the nose keeps bobbing up and down as it flies forward. It never sits level and still.

What I initially did which I was going to try tomorrow was more nose weight. At first it seemed logical but now I'm not so sure.

When you mentioned how little throws you needed I realised mines the opposite. I moved my control horns out a hole for tomorrow. Now if it's too nose heavy then that would explain the lack of control authority. Which then would suggest taking weight away from the nose as opposed to adding some.

This still leaves me confused on the nose bobbing. I can't see how making it more tail heavy would stop the bobbing. It would change the reflex though which could be the cause I guess. :shrug: