FPV40 kfm-4 v2 build log

[T-Richard]

Inspired byt the recent clean fpv set-up flitetest video I decided to redo my fpv wing. I slapped together a Kfm-4 version of the fpv40 and was pleased with the results. However, a few things bothered me, First I just hotglued everything used minwax to paint it and kinda went quickly with everything. I was stunned by how well it flew regardless but after crashing it because my batteries flew out ( will definetly address this issue) I had a few things to do before it was ready again. The wing actually held up well. The camera however, did not. Either way time to rebuild.

Here are some ideas to improve the plane

- Gorrilla glue layers together without paper on the foam board
- Add central 6mm squar CF spar, less "floppy:
- increase wing area by going to the "xl Version"
- 2 layers in the center in order to increase thickness and further recess electronics in the wing also stronger elevons
- wire everything as per the epiosde of flitest
- use my simple osd and arkbird 433 for improved FPV experience
- use 2x 2200mah batterys a WDR fpv cam and 808 for recording (the wing needs plenty of nose weight and glided great with the previous set-up so this additional weight does not concern me
- bigger motor
-place vertical stabilizers inside (aesthetics in my opinion)
- metal gear servos
- tape lamination vs paint (Stronger and I beleive lighter as well)

I am about to get started and will post progress pictures

 

[T-Richard]

the 2 middle sections have been cut, glued, and, de-papered where they joim

The kf step are pu in, This time a 30 in central section is cut out and an additionnal 5 inch section is glued on either side to help keep the center section strong. I also dug in a central 6x6 square cf tube exactly at the CG. I also glued a leading edge cf rod of 1x3. It's a long process with having to wait for the glue to dry.. more to come,

Also the forum doesn't like my pictures... gotta make em lower res i guess

 

[Foam Addict]

Very nice, It's hard to find a good flying wing build log. I'm glad you're documenting your build!

 

[T-Richard]

spar placed and glued

Kf complete and CF rod placed on leading edge. I remove 3/4 inch of paper in the front and will sand it to a nice aerodynamic shape in latger steps

 

[T-Richard]

a Little lost.



CF spar in and Kf installed, only one last layer to go but waiting to mount electronics in before i make it.



the question is, I was planning on maing this heavy hauler long range ship but am now thinking of sticking to a single 2200, light cameras, standard range radio rx, and 200mw fat shark and keep all the long range stuff for my canadair seaplane for long range lake fpv... might better for photography/ scenery and keep this one light and fast for fun flying and ease of transport....

Anyways, will sleep on it. waiting on packing tape colours to come in but will mount servos later. That Cf 6m square spar makes this thing Rock solid. looking forward to fly it

 

[T-Richard]

Servo wires twisted and mounted and laminated the bottom and part of the top. Ran into problems getting the Arkbird system to work the throttle

Awaiting solutions before I wire FPV system and get ready to maiden

PM me if you know how to set up arkbird system

 

[T-Richard]

Finally progress. got my uhf and radio working well and will maiden the 40 inch wing later this week!



While I was waiting to figure everything out I made a small 30 inch fpv wing kfm-4 again for short range fpv fun. Same build techniques as the big one.

I maidened yesterday without FPv and WOW! This has to be my favorite, capable of unlimited vertical climb, 15+ minutes of agressive flying, very strong strong can be aerobatic, fast and has a great glide!

here it is



I am using the following;

Suppo 2208/14 1450 with an 8x4
simple series 18 amp esc
tg9 servos (should go for metal gear next time)
orange 6ch dsm 2
Boscam lightweight 200mw 5.8ghz vtx
Fatshark filter
Sony 600tvl fpv cam
2200mah 3cell

The design is based on Schraut5 delta or mini zephyr but I used foam board and kfm-4 vs insulation foamboard and kfm-2. I also have a nice spar in the middle and a leading edge strip of cf. the result is a stiff and lighweight airframe. Best I've made so far.

Videos this weekend if I can get my 808 working