RC Keith CNC Hot Wire build log

[bracesport]

Hi Nate - so what is your recommendation for a CG point on this wing - I cut down a DTFB DLG wing to 1.0m (chord is 170mm, tip is about 110mm, and there is about 35mm offset to the tip) - Oh, it still has the DLG dihedral too - it is my first time with a wing and I have it balanced @25% and this required quite a lot of reflex to get it to launch?

any tips or insights welcomed!

Plank 2.0 is ready for maiden. Honestly the hardest part here at the end was trying to figure out how to program elevons in my x-lite as i hadn't used the version of opentx it has. Final weight and stats are in the second pic below. May be some time before i can get good wind and an opportunity to get maiden done.

 

[thenated0g]

I have been watching your stuff on youtube, but i forgot to comment. Nice looking wing.
I use this cg calculator and i usually set it to 20-22%. I mostly use the pw51 airfoil and its recommended is 22 and has never been wrong with that.

If you do adjust it to 22 or 20 be ready to need less stick movements. If it was controllable at 25 i would just down to 22 (remove 1/2 of the reflex or all of it and start over)

I input those numbers you gave me, take a look, not sure if this matches correctly your wing, you can adjust it.
http://wingcgcalc.bruder.com.br/?un...e4=0&panelspan5=0&chord5=0&sweep5=0&angle5=0&

 

[bracesport]

Thanks Nate - Ok, great! review the CG forward. I will make sure I have some rate options for toning down the throws and dial up the expo!

Looking at the data, I will be moving the CG back a tad to achieve 22% (my 25% figure is just the actual measurement @25% of the root).

 

[thenated0g]

i would say for 99% of all my wings/planks i have ever built i just leave that app at the default, i think its 20%. If i know a particular airfoil should have something different than ill change it. IE peter wick stuff (pw51 and pw1211) ill change it to 22, everything else i dont touch it. and its always been great.

 

[bracesport]

I reckon that if I plug on 20% it will be close to the CG I have!

 

[thenated0g]

Cut out v1 (cardboard test) of my "arms" i am designing for the Bow hanger. I am copying the setup from the windyhill cnc setup which is essentially 2 parts. The top part is a hanger for the rigid top part of the bow to hang and slide on as the towers move apart. The bottom part is a rigid location for a brass eye that holds the hot wire in its location and also allows it to slide as the towers move.

Another issue this is dealing with is that the neutral/home location of my old towers was a couple inches off the table so i had to elevate my foam. This arm design gets it down very close to the table.

***oh yeah the other major issue i was dealing with on this design was that at the extreme angles the bow will get on this configuration i needed to get the pivot points much farther away from the towers so the bow and towers dont interfere with each other.