64mm EDF Scratch Build

[Andre]

Fly Yes... Land No

So Saturday I got out with the EDF Plane and it flew!
Big toss at WOT and it went up... Backed the power off and did a few laps... Then I decided to try to bring it in and land...
Yeah keep the throttle up.

The nose dug into the snow and broke the fuselage off. No video. I double clutched the button. Boo.

Did a quick field repair but that did not last. So brought the plane home and did a full rebuild.

Repaired the wing and eliminated the under carriage fuselage.

Also swapped in a smaller receiver. If the weather is decent I'll get out on Sunday.

 

[Andre]

Sunday's flight

Sunday's flight was semi successful.

Still have some tuning to do but getting closer and closer.

 

[Andre]

Oh Yeah!

She flies and not to bad at that.

But only getting 3 minutes out of the 2650 4S.

I will have to try some 3S next for kicks since the plane did fly well at 50% power.

You more or less have to do a foot ball throw to get it going but I'd like to find a way to drop the weight.



Video coming shortly.

 

[Andre]

 

[Andre]

So next task is to test with a 3S and then to figure out how to up the efficiency and add lightness.

 

[Andre]

Reading up about the thrust tube specs.

So narrow exit = more speed
Wider = more thrust and also lowers the demand on the motor.

Before I redo the tube into an actually round design I'm going to cut open the current design and see how this works.

Have to admit this has been a great winter project.

Thanks Mike!

 

[PHugger]

Very disappointed that you missed the AfterHours Podcast again!



Best regards,
PCH

 

[Andre]

Very disappointed that you missed the AfterHours Podcast again!



Best regards,
PCH

I was on top of a mountain with limited WIFI



But rest assured Chris and I will team up shortly.

 

[Andre]

Actually when Chris asked me if I could join my Wife was very supportive despite the fact we were on a romantic get away together.

But as I mentioned the wifi connection was very poor and the audio would have been below par.

Kicking myself for not bring the EFX out last night. Would have been perfect conditions

 

[Andre]

A few mods

So removed 1" from the thrust tube.

I also redid the nose. Shorting it that by an inch as well.

No real weight savings but if the thrust is improved I'll move onto the next phase which is a rounded tube.

The challenge after that will be to come up with a fuselage which incorporates the fan.

 

[Andre]

Perfect on 4S

So today despite the cold temps and high winds I got out to fly the EDF Plane.

- We need to name this puppy.



The cut back thrust tube made the plane fly a lot better then previous.

I did try it on a 3S but it fell out of the sky.
So I have some repairs to do.

Video to be posted soon

 

[Andre]

 

[Andre]

2 more great flights in some serious winds on Sunday.



We are still working on the name.

Buzzing Bee was one suggestion so far.

The next phase of this project as I mentioned is to drop the motor down a touch more.

I really do like the flat belly makes for great landings so really all this will do will make the plane a touch more aerodynamic.

Just have to ensure I do not restrict the intake.



I'm also toying with the idea of reducing the wing span by modifying the centre section.

We shall see

 

[mesolost]

I have this idea in my head for an EDF mod I want to try when I get to that level. Take a servo and hook it to some restrictor fins on the output so you can run it wide open for slow speeds and choke it down for super-sonic flight. (scale wise that is =p ) Like the setup an F-16 has on it. Or even set it up as a vectored thrust system and mix in the rudder with it. What do you think?



The bits on the back are what I'm referring to. It's collapsible cone but I figure you could have fixed upper and lower flats and have the 2 sides setup as "control surfaces" and use em like the real jets do. Let me know what you think and if you try it I'd love some pics and flight characteristics so I know if it'll be a good design I can enhance upon later.

 

[mesolost]

Alrighty, talked to dad cuz he's the air force guy and it's called a divergent/convergent afterburner nozzle and the individual flaps that make it up are referred to as "turkey feathers." They work backwards from the pure EDF system and contract at idle to maintain back pressure and are automatically controlled by the throttle/after burner. ^_^ Whether you do it or not I'm gonna try it at some point. Put the throttle mix on a switch so I can leave it wide open for take off and have it auto close on WOT. If I use 2 servos, one for each side, then I'll mix in the rudder for vectored thrust on top of the "after burner" effect. =p

 

[Andre]

http://arxangelrc.blogspot.ca/2013/11/sky-angel-mini-t-45-50mm-edf-jet.html

 

[mesolost]

That's a LOT more elaborate than I had envisioned and if I had a 3D printer I'd definitely be doing it like that. But at the same time I'd like to do the turkey feather idea if I'm going 3D printed. I can see that taking 4 servos to control it though but it would be a hybrid vector thrust AND a flow restrictor for higher speeds. Would having the thrust nozzle contract actually work to increase the speed? Like going from O to o in size???

 

[Andre]

I'd just do 2 servos and put the setup on a switch open for thrust and closed down for speed > =

The real question is what kind of tail weight would that add.

The other option could be to have 2 ports and simply close one off for speed mode.

I'll have to draw that out.

 

[Andre]

Nuts.

Bearing let go.

 

[Andre]

So I've not dug into the motor yet but I admit I'm tempted to order 2 new ones and 2nd ESC...

Do a twin motor on 3S vs 4S so I dont have to worry about burning them out.

Thoughts????