Making and Replacing a Brushless Motor Shaft - https://www.rcgroups.com/forums/showthread.php?1240725

Prop Savers - Fitting, Using, Testing, & Making Thera-Band Bands - https://www.rcgroups.com/forums/showthread.php?1419378

Jack

Ok will get the shaft cut.

Need to repair the wi g again it took a sudden dive shortly after launch and wouldn't pull up. I suspect the battery came loose

Think I need to build a new one... Having to many issues with this one now... Keeps flying towards ground on launch until you get i air then it's fine. I think there must be a crack somewhere I can't see and it's causing motor to tilt givj g down thrust.

It also will not do reversals cleanly. It always tries to roll out the same way. I've learned to counter it its so predictable. It also tries to roll out of inverted.

If anyone wants to know what it flies like with down thrust (and the motor installed like how the op has it as far up as it can) well wonder no further. It flies like crap that is if you manage to launch it and pull up before it hits the ground, its weird in the air feels. Unstable.


Disocered my motor mount allowed the motor to wiggle up down a few degrees. Its the dst 1200 motor. The mount holds the motor with 2 grub screws so it was good when i tightend Ed it up but after runnj g the motor it was able to move in the mount ehi h explains the sudden pitch down.

So it wouldn't fly until it had enough speed. Launch would sent it to the ground and full up wouldn't pull up until it had enough speed.


Also think I've found why it would like to roll out of loops and reversals. One of my elevons the hinge had given way from the end till about a quarter way back so I guess it was flapping under load.


Havnt been able to test yet as I had it in car yesterday when I was out but the hotglue melted on the firewall due to sun...

I've also decided to test a smaller 850mah battery to loose some weight since I'm getting great estimated 10 minutes maybe more with the 1000mah 3s

So ow that I'm figuring things out. Once the weather's better with low wind I. Gonna show the Kung-fu combat wing really shifting on the dst 1200. Motor on 3s.

Tried my 850mah batteries. Slightly lighter but lacking the punch the 1000's have. Expected as the 850's were my trex 250 heli batteries they got abused.


Still having issues doing loops. It always twists out. But I can do reversals fine...

Found tail heavy. Its about as far back as I can get the battery. Very twitchy on elevator. So I'm definatly in the right cg range.

Flies ok upside down.


I might have to make a new one with carbon spar. Wondering if its warping in flight under load and possible breaks I can't see

If you build a new one, build as designed.

Mine flew perfect in every way right from the start. My only change was a single vert stab and lighter electronic bits.

Originally Posted by goldguy

If you build a new one, build as designed.

Mine flew perfect in every way right from the start. My only change was a single vert stab and lighter electronic bits.

Mine flew great up until the motor fried and I put the dst motor on it. Fro. There its been problematic.

Thank you, Thomas, for the plans for Kungfu and all your other planes. So far i have built this one and the Trottel, which is waiting for the maiden. The next project will probably be the Jupiter duck and your Mauersegler.

My setup is:
- Turnigy CF2812 1200kV
- 3S 1000mAh 20C
- 7050 prop
- cheap 20A ESC
- FrSky D4RII

AUW is 255g, the 3S battery adds another 88g. I had 8 flights so far, all went without problems, except for the very first landing which was a bit hard and caused a slight damage, especially to the right wing tip. I added skewers to the wing tips, which are standing out about 1cm. I hope that the skewers will help the wing tips. I don't know how helpful they will be because there were no hard landings since then.

For these first flights i reduced the throttle range to 75% and the throws to 60%. Even so, and with very old lipos Kungfu flew great. It is a very responsive model. I'm looking forward to getting my new batteries and flying full throttle and with maximum throws next time. I also want to try a 7x 6 prop.

I used pallet strapping for the first time. It is incredible how stiff the wings got, almost like solid wood. I think i'll use this method a lot in the future.

The 1° down thrust turned out to be too little for me. I'll have to increase the inclination of the thrust line.

Concerning the error on the plans, i noticed that just the vertical symmetry line is tilted a bit to the left and one of the outer edge lines for the fuselage was wrong. The plane itself is drawn correctly. So there was no need to cut one half of the wing and to mirror it.

Thanks again Thomas for generously sharing your projects . And a big thanks to Modell Aviator for all the free download plans.

Hi, can someone say what the measurements are for control surface before i attempt the maiden. Thank you

Originally Posted by glenbees

Hi, can someone say what the measurements are for control surface before i attempt the maiden. Thank you

It is not very important. The CG has to be correct. To far back and it will fly terrible.

Okay, thank you.

Originally Posted by glenbees

Hi, can someone say what the measurements are for control surface before i attempt the maiden. Thank you

With a up and down deflection of about 45 degrees or so that will be a very twitchy and maneuverable plane. If you have that much deflection it is best if your TX has a high and low rates switch that you can manipulate in flight. Set the low rates to 50% and you'll only get half of the full deflection when you are on low rates. And for a maiden flight and most sports flying that is all the deflection you'll ever need.

For the maiden flight you want to be able to balance the plane setting level resting on your finger tips and the red line in this image or slightly forward of that line. It will be a little less maneuverable if it balances 1/4" to 1/2" in front of the line but it will make the maiden flight easier. That small black and white circle is the CG location.

After you get it flying you can move it back a little (to the line) and it will be a little more maneuverable.

The plans call for a CG location of 125-127mm back from the "motorsplant" (in German) and I'm not sure if that means in back of the firewall or what....

Good luck with it!

Jack

Originally Posted by jackerbes

...125-127mm back from the "motorsplant" (in German) and I'm not sure if that means...

Yes, Motorspant = firewall

Originally Posted by van3st

Yes, Motorspant = firewall

Thanks for the help with that! So 125-127mm back from the firewall would put the CG a 4.92" to 5" back from the face of the firewall.

Jack