Thread Tools
Sep 18, 2016, 04:03 AM
InceCreations
vincent123's Avatar
Got a bit of work done.

The EDF is indeed a huge hole in the wing structure, hope my concept is strong enough.

I have 2 main carbon spars (white colored), reaching from the root till the wing droops down.
Carbon spar thickness is 3mm, which I will route in my CNC machine.
I calculated the strength of one carbon spar and it would sustain 13G.

The other spars (dark brown) is a 2mm plywood routed outline, also going from root spar till mid of the plane. It's a 2mm width and 7mm height spar, I know it's not so strong (can sustain only 0.8G). But I believe this is ok, as long as the main carbon spars do their job, no ?

The EDF sits in a sadle of the second carbon spar.

As I always do, I will burry the EDF in the wing and plank it to a close.
For maintenance the EDF, I will be able to take out the read EDF outlet part, of course I need to cut the planking. The rear outlet is then loosened with the same bolts which fastens the EDF in the sadle.

By doing this, I have a clean planking and with some little cuts I 'll manage to get the EDF out, some little cosmetic repairs and ... done.
Last edited by vincent123; Sep 18, 2016 at 11:32 AM.
Sign up now
to remove ads between posts
Sep 18, 2016, 12:16 PM
InceCreations
vincent123's Avatar
all ribs ready
Sep 18, 2016, 12:58 PM
Registered User
iron eagle's Avatar
I think you need to come up with a way to extend the carbon a bit further out into the wing.
You could always make a mold for your carbon spars and lay them up using carbon tow and cloth.
Sep 18, 2016, 01:01 PM
InceCreations
vincent123's Avatar
Futher into the wing towards the tip you mean, why?
Sep 18, 2016, 05:52 PM
Registered User
iron eagle's Avatar
Because of the loads the outer portion of your wing will have to endure because of the tip fins serving as landing/takeoff skids.
Sep 19, 2016, 12:35 AM
InceCreations
vincent123's Avatar
Better to be sure, I'll make them a bit larger,
gonna use also carbon 4x4 for the main spars till the tip.
Sep 24, 2016, 05:02 AM
InceCreations
vincent123's Avatar
Main spar altered, looks superstrong !
Sep 24, 2016, 12:14 PM
Registered User
iron eagle's Avatar
Wow, that should work.
Sep 24, 2016, 12:27 PM
InceCreations
vincent123's Avatar
Quote:
Originally Posted by iron eagle
Wow, that should work.
Yeah, is a bit overkill, i know
Sep 24, 2016, 06:06 PM
Registered User
iron eagle's Avatar
You should have no problems with flutter.
Sep 28, 2016, 11:54 AM
InceCreations
vincent123's Avatar
Thinking about an RDS system, as Stuart suggested for the FZ5.
But is such a system as accurate as a standard horn-horn solution ?
And strength wise, should nt the servo be a tat stronger in order to have as much moment as with the standard solution?
Sep 28, 2016, 04:28 PM
Registered User
iron eagle's Avatar
These setups are used by the sailplane guys you should take a look at what they do with them. I am with you as far as the thoughts about using stronger servos, it does not look like you get the same type of mechanical advantage you get with a setup using horns. I like the idea of no exposed control linkage and have like the results I get from doing it that way.
Sep 28, 2016, 04:40 PM
less is more
Knoll53's Avatar
I would suggest that the geometric leverage is opposite with RDS as compared to standard servo arm and horn on elevon. that is, there is more power and finer control at maximum deflection with RDS, which is backwards from what I want.

Also, RDS is vulerable to jambing with any debris in the box at the elevon. I would never use one at the beach. the sand would surely jamb it.

You might consider building your own Horten style elevon linkage. I built this prototype from brass tubes. It has a rigid pushrod running down the wing.

If you really want to show off, you can control multiple elevons from one push rod with each elevon configured to deflect in it's own pattern. It DOES take a little geometry to calculate deflections.

Sep 29, 2016, 12:21 PM
InceCreations
vincent123's Avatar
Quote:
Originally Posted by Knoll53
I would suggest that the geometric leverage is opposite with RDS as compared to standard servo arm and horn on elevon. that is, there is more power and finer control at maximum deflection with RDS, which is backwards from what I want.

Also, RDS is vulerable to jambing with any debris in the box at the elevon. I would never use one at the beach. the sand would surely jamb it.

You might consider building your own Horten style elevon linkage. I built this prototype from brass tubes. It has a rigid pushrod running down the wing.

If you really want to show off, you can control multiple elevons from one push rod with each elevon configured to deflect in it's own pattern. It DOES take a little geometry to calculate deflections.

Correct, in the middle we want it to be exact and fine..

Wauw, that's a nice linkage solution !
Any details on paper or sketch how you made it ?

Classic horn setup looks sooo much easier
Sep 30, 2016, 10:22 AM
less is more
Knoll53's Avatar
If you go full screen on the video, you can make out the brass tubes. One fits inside of the other and there is a music wire pin drilled thru the tube connection with some carefully applied solder. this pin is at an angle and this angle is what set up the amount of movement and (inversely) the amount of power.

There is at least one more variable that I have forgotten at this point. I studied the available horten linkage in order to take a stab at this prototype. In this prototype, the pushrod really must travel a lot to get the big elevon deflections, which I think is a good thing.

This design is all about designing the pinned connection. It is a high stress condition and must be good materials. hard brass or better for my mock up. CNC milled alum. with a music wire pin might be the way to go.



Thread Tools