Comment by Justin Stiltner on August 14, 2012 at 12:21pm

Your ESC is overheating because the BEC inside it is a linear bec and is putting out a lot of heat as it regulates the 11.1v down to 5v for your servos and autopilot.  If you want to cure this put in a seperate switching BEC at least when you are on the bench, or power your electronics from a seperate reciever pack.

Your elevons are going to have some weird movement because of the way you have your pushrods connected.  If both the servo arm and the control horn are parallel and the pushrod is perpendicular to them then the movement between the servo arm and the control surface will be a one to one ratio.  The part of the control horn that you attached your pushrod to is supposed to be cut off and uses as a plate on the other side of the control surface to reenforce the attachment between the horn and the surface.  It also needs to be turned around front to back.   The way you have your pushrods connected you will have more downward throw than upward throw, which could cause some weird control issues.  Also dont forget that your pushrods need to be able to push the surface down as well as pull it up.  Will your pushrods buckle when the servo tries to push?

It looks like you are well on your way to having a neat plane!  The construction of the airframe looks pretty nice, and you really took your time to fit all the components into the foam.

Good luck!

Comment by Kabir on August 14, 2012 at 7:05pm

Thanks for your help Justin. Will it be safe to fly with the on-board linear BEC in my JDrones ESC for now? I am not in a position to buy a separate switching-mode BEC and so I might build a normal linear out of parts that I have.

As for the pushrod/servo etc. ,thanks for making me aware of the problems. So far, I have noticed that the rods don't buckle, but are just flexible enough. The part that was supposed to be broken off is attached to the horn by a bit of flexible plastic which I noticed that absorb the servo vibration. The elevon throw 'seems' to be the same in both directions, but need to inspect.

Please advise!

Kabir

Comment by Martin on August 14, 2012 at 9:25pm

A linear regular regulator will still be just a linear regulator. You building one doesn't change that fact. You shouldn't use a linear regulator for currents over 200 mA. With your setup the current is probably much more than that. If you have NiMH or NiCD batteries then the cheapest option would be using them to power your servos directly from a 4 cell pack.

Servo vibration? If your servos are twitching then you have interference or bad servos. Servos don't vibrate.

Comment by Greg Fletcher on August 14, 2012 at 10:50pm

You need to look at the angle between the rotation point and the end of the arm. The one for the controlled should be parallel to the one for the servo. The angle for you controlled is way off. There should be no flexing of the control link at all. Every thing should move freely. Is your hinge point on the bottom or top of the wing surface? Control reliability is everything. With out it you will surely crash.

Comment by Kabir on August 14, 2012 at 11:38pm

http://www.hobbyking.com/hobbyking/store/__3735__HXT_UBEC_5_6v_outp... Will it be enough? Is it a switching mode one?

Comment by Kabir on August 14, 2012 at 11:40pm

@ Greg The hinge point is in the middle of the sheet used to make the elevon. Could you please explain you angle thing. Sorry for being nooby.

Comment by Hawhoo on August 15, 2012 at 12:58am

I fly a similar plane and esc but I have my ESC in the airflow. If you mount your esc more on top (in direct airflow you should be fine).

As far as your Control horns are concerned - This is something that you should really fix. The hole of the control horn needs to be exactly on top of your Hinge-line!

Here are a couple pictures:

http://www.google.com/imgres?hl=en&client=firefox-a&hs=v8t&...

http://www.google.com/imgres?hl=en&client=firefox-a&hs=v8t&...

http://www.google.com/imgres?hl=en&client=firefox-a&hs=v8t&...

or this here: (look for control horn installation)

http://www.rcgroups.com/forums/showthread.php?t=1245580

The Plate with the three holes in it that is just connected with a stub to your control horn should be cut of and is meant to be used as the bottom plate mounted on the opposite side of the control surface to stabilize your control horn. Check out the pictures!

Aloha and good luck the rest looks great!

Moderator Comment by Graham Dyer on August 15, 2012 at 1:10am

Swept flying wings need their CG very far forward compared to conventional aircraft, with your battery where it is AND the motor at the rear the CG is going to be way too far back.

Do you know how much current you are drawing? Also what is the weight of the plane?

Comment by Petrus Botha on August 15, 2012 at 1:35am

1. Your control horn setup looks wrong, see the diagram attached to correct it.

2. Why use plastic for the control rod when a piece of wire with bends wil suffice

3. What is the thickness of the ailerons?, they seem extremely thick and might provide a lot of additional drag

Comment by Melih Karakelle on August 15, 2012 at 4:11am

Hi Mohammed,

I guess you have to learn the aerodynamics before making your own frame.
Wing form looking weird and very thick. Your flat back ailerons will generate big vacuum (wing form too) .
Did you tested your plane without any electronics? It must be glide smoothly before motor flight.

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