3D-Delta, 3d epp KF delta jet, *VIDEO* *PLANS* - Page 3 - RC Groups
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Jul 06, 2010, 07:42 AM
RIP Azarr - "Old age is not for sissies"
Azarr's Avatar
I'd think that knife edge would be difficult without a major increase in fuselage side area. Either that or lots of power. The Extreme Flight Outlaw is a delta that will knife edge with ease and has very little side area, but tons of power.

Hope I'm wrong Looking forward to plans, just finished another Yak and nothing on the building table at the moment.

Azarr
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Jul 06, 2010, 12:11 PM
Winging it >
leadfeather's Avatar
Actually there is plenty of fuse side area for knife edge; doesn't require a lot of power to fly on knife edge. The only issue I have is that the jet wants to roll out of knife edge. Increasing the fin span helped make it easier to hold knife edge. Further increases in fin span would probably continue to make it hold knife edge better.
Jul 06, 2010, 12:49 PM
When pigs fly rc
rcrich's Avatar
LF
What did you use to hide the carbon fiber rod in the wing surface or is it painted white like the foam? Did you use 6 or 9mm epp? Thanks Rich
Jul 06, 2010, 01:08 PM
RIP Azarr - "Old age is not for sissies"
Azarr's Avatar
Quote:
Originally Posted by leadfeather
Actually there is plenty of fuse side area for knife edge; doesn't require a lot of power to fly on knife edge. The only issue I have is that the jet wants to roll out of knife edge. Increasing the fin span helped make it easier to hold knife edge. Further increases in fin span would probably continue to make it hold knife edge better.
Can't you just mix it out? Not that knife is a deal breaker, it looks like it flies great anyway, knife would just be an added bonus.

Azarr
Jul 06, 2010, 03:49 PM
Winging it >
leadfeather's Avatar
Quote:
Originally Posted by Azarr
Can't you just mix it out? Not that knife is a deal breaker, it looks like it flies great anyway, knife would just be an added bonus.

Azarr
I'm not sure how I would mix this out?? It will roll back to either upright or inverted level flight depending on what side it tilts slightly to during knife edge.

I think knife edge is attainable:

1) electronic solution, gyro on the roll axis.

2) aerodynamic solution, keep making the tail fin span large until the roll becomes "neutral enough" to allow fairly easy knife edge with out rolling out on it's own.
Jul 06, 2010, 04:20 PM
Sopwith Camel's Cousin
Quote:
Originally Posted by leadfeather
I'm not sure how I would mix this out?? It will roll back to either upright or inverted level flight depending on what side it tilts slightly to during knife edge.
...
Wing sweep is supposed to act as effective dihedral
(only there are 2 stable angles: upright and inverted,
instead of just upright),
so all that wing sweep in the delta is probably making it want to roll out of knife edge.
In addition to your possible solutions, you could also try
adding more leading edge sweep to the vertical section,
so it will act like effective dihedral when in knife edge.

-Your friendly neighborhood amateur armchair aerodynamics wannabe
Jul 06, 2010, 05:18 PM
RIP Azarr - "Old age is not for sissies"
Azarr's Avatar
Quote:
Originally Posted by leadfeather
I'm not sure how I would mix this out?? It will roll back to either upright or inverted level flight depending on what side it tilts slightly to during knife edge.
Pmix with rudder as master and aileron as slave, mixed in both directions. One of my Yak's rolls right and pulls to the top in knife edge in both directions. I have a mix with Master = Rudder, slave = aileron and slave = elevator. + in one direction, - in the other.

The aerodynamic solution would be the best, of course, but I actually liked the way it looked without the added area on the bottom. (and, less confusing for my old eyes)

Gyros: I have a couple of cheap GWS gyros I played with for a while on a round thing with equal area (two circles in a cruciform arrangement) for both the fuselage and wing and they worked well.

Azarr
Jul 06, 2010, 06:18 PM
Winging it >
leadfeather's Avatar
"The aerodynamic solution would be the best, of course, but I actually liked the way it looked without the added area on the bottom. (and, less confusing for my old eyes)"

I agree on the looks thing. I had a VFO for a little while; orientation made flying a bit more of a challenge.
Last edited by leadfeather; Jul 08, 2010 at 12:53 PM.
Jul 06, 2010, 07:49 PM
Sopwith Camel's Cousin
Quote:
Originally Posted by leadfeather
The aerodynamic solution would be the best, of course, but I actually liked the way it looked without the added area on the bottom. (and, less confusing for my old eyes)

I agree on the looks thing. I had a VFO for a little while; orientation made flying a bit more of a challenge.
Too bad there is not clear EPP (or some other foam). That would solve the need for "invisible" surface area.
The best I can think of: either clear PET plastic sheet from say bottles (kind of heavy), or
a CF rod border outline and clear plastic (like Mylar?) film stretched across it
(sort of like an IFO or Vapor wing).
Or use black EPP to add the area? Hopefully less confusing and perhaps black EPP may blend better into the background (rendering it less visible).
The latter reminds me of a RC helicopter beginner's book's warning: do not use black rotor blades, they will be hard to see when spinning.
Jul 08, 2010, 12:56 PM
Winging it >
leadfeather's Avatar
I think I'm not going to get to concerned about the knife edge for now. This jet is very fun and highly maneuverable.

I am thinking about throwing a bigger motor on and seeing how it does when pushing the speed limit.
Jul 08, 2010, 01:00 PM
When pigs fly rc
rcrich's Avatar
I agree, knife edge is not needed. From the video she looks like alot of fun. Good luck with the bigger powerplant.
Jul 08, 2010, 06:25 PM
Winging it >
leadfeather's Avatar
Quote:
Originally Posted by rcrich
I agree, knife edge is not needed. From the video she looks like alot of fun. Good luck with the bigger powerplant.
This is the power system I plan to try; works very well on my Stryker. Good power for the price.

motor 2409-12T
prop TGS 7x6E
esc HKSS 25/30
battery Rhino 1050 20C
Jul 08, 2010, 06:43 PM
Registered User
Dan, have you considered adding two smaller verts on the control surface of the elevons? Worked here anyhow... I didn't use for knife edge, but I did for more total plane stability. It might help in your situation too. That's a big honkin motor. They ought to do a prettier wind for the pics don't you think?
Jul 09, 2010, 06:42 AM
Winging it >
leadfeather's Avatar
Quote:
Originally Posted by tymbrewolf
Dan, have you considered adding two smaller verts on the control surface of the elevons? Worked here anyhow... I didn't use for knife edge, but I did for more total plane stability. It might help in your situation too. That's a big honkin motor. They ought to do a prettier wind for the pics don't you think?
T-wolf what do you think the small verts would do for this 3D Delta? I have tons of vertical surface already.

The 2409 12T is very powerful, even with the "less than pretty wind" the factory does. I wonder how much power could be squeezed out of this motor with a good rewind? Expected speed range should be zero (hover) to ballistic. This plane doesn't really need this much power but I thought it might be fun to try it out.
Jul 09, 2010, 07:06 AM
Registered User
I was just thinking that if you added verts on towards the ends of the elevons that it might add anti roll stablility other than at the center and act like leverage. I would think there would be sweet spot size to help with roll out but without dampening the aileron action. Remember, I fly and build by TLAR, not by any empirical knowledge of bubbles, turbulence etc...


Dan, look at boxhead's delkan thread. He uses to little wedges on the elvons with no center vert. Completely stable for non 3d very sporty flying. That is where I got the idea.

And finally, my thought to your knife edge issue is the same with the long nose pointy delta as they may slip a little in a turn. Now that you reduced the nose of your fuse for more control, you are getting a little slip on the nose which causes a slight barrel roll causing your knife edge roll out. While it would change the whole look and probably the potential speed of your already cool plane, do you think that chopping of the first three or four inches of the nose and reattaching the motor there wouldn't help with 3d stuff? Then again, all planes are compromises. I would keep the lines and go for speed too. You have plenty of great 3d stuff to play with. Just some thoughts from the bench. I would say from the cheap seats, but I have actually had some fun with my own designs. Still, I only get to play the last two minutes if we are 40 points ahead at the big boy games.
Last edited by tymbrewolf; Jul 09, 2010 at 07:39 AM. Reason: added last thoughts


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