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Aother DELTA wing airfoil question - 2/2/2013 1:08 AM   
Jaspur_x


 

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From: Friedens, PA, USA
Status: offline 		ok so my foamy delta didn`t turn out very well.
Long story short,I epoxied 3 pieces of 4" wide,1.2" thick foam together then cut the triangular shae of the delta. I  eoxied 1/16" balsa on the flatbottom airfoils side for some added strength and landing survival.
the airfoil got me buggered though, the epoxy ridges were more a contender than the bread knife I was using to cut the airfoil. after adding monokote I noticed that between my breadknife skills and the momokote iron, the airfoil rear of the peak of its height was all concave like an undercambered wing but the concavity was on the to of the wing.

What disasterout airfoil did I create? I know it will still fly somewhat like the flying pancake but how BAD will it fly is my Question?  I know I know, I should have just left the darn foam 1/2" thick and flat on both sides right?

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RE: Aother DELTA wing airfoil question - 2/2/2013 3:56 AM   
Andrew


 

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Status: offline 		Interestingly, an airfoil that shows some concavity about 2/3 of the way back from the leading edge and with an slightly upswept TE is called a reflex airfoil. Primary application is on flying wings and deltas. Who knows, you may have inadvertantly helped yourself out.

On the flat plate deltas I've built, I set both elevons up with a very small upward pitch - this tends to emulate a reflexed airfoil.

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RE: Aother DELTA wing airfoil question - 2/2/2013 4:36 AM   
combatpigg



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Status: offline 		For 1/2A scale, the delta needs to be really thin and light for it to be as fast as it can be.
I've never been able to visualize how to get this done with foam any easier or better than getting it done with balsa wood and possibly a tubular spar made from either FG or CF.



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RE: Aother DELTA wing airfoil question - 2/9/2013 11:54 PM   
Jaspur_x


 

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quote:

ORIGINAL: Andrew

Interestingly, an airfoil that shows some concavity about 2/3 of the way back from the leading edge and with an slightly upswept TE is called a reflex airfoil. Primary application is on flying wings and deltas. Who knows, you may have inadvertantly helped yourself out.

On the flat plate deltas I've built, I set both elevons up with a very small upward pitch - this tends to emulate a reflexed airfoil.


I`m hoping to find out tomorow if it will fly , or should I say if its possible for me to actually fly it lol

I know a part of the problem is that wil be I don`t have CP`s flying skills


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RE: Aother DELTA wing airfoil question - 2/10/2013 12:10 AM   
Andrew


 

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quote:

ORIGINAL: Jaspur_x

I know a part of the problem is that wil be I don`t have CP`s flying skills



Not many do - he flys some insane planes.


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RE: Aother DELTA wing airfoil question - 2/10/2013 1:07 AM   
combatpigg



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Status: offline 		Anybody can "build up to" flying fast if you do it in stages with planes that have a correct CG, conservative control surface throws and "user friendly" wing loadings.
If the plane isn't set up right there isn't any amount of skill that will fly it with relative ease.
I flew TD .049 planes with 5x3 props for many years thinking that was quite a thrill. Those plane probably maxxed out in the 70 mph range, but at the time they seemed like total rockets. Then years later the Norvel and VA .049-.061s raised the bar somewhat.
I tried Cox 5.5x4 pitch 1/2A props looking for more speed but didn't see much noticeable difference. Nothing dramatic, until I cut one down to about 4.25x4. That really made a difference.
Finally, APC came out with the 4.2x4 prop and that pole vaulted all of the hot 1/2A engines into the 100 mph [capable] range, but you need a very low drag airframe [think small, thin & light] for these props to work.
I don't think there are any commercially designed RC planes that meet this criteria...including a standard ACE RC GLH.


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RE: Aother DELTA wing airfoil question - 2/10/2013 11:42 PM   
Jaspur_x


 

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quote:

ORIGINAL: Andrew


quote:

ORIGINAL: Jaspur_x

I know a part of the problem is that wil be I don`t have CP`s flying skills



Not many do - he flys some insane planes.




Sanity isalways a matter of personal perspective lol  I really don`t have the reaction time skills to fly a plane as fast as CP but I can`t build 1 as good as he does either as he makes good points ,as usual.

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RE: Aother DELTA wing airfoil question - 2/11/2013 1:06 AM   
combatpigg



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We all have different reaction times. Mine never were as good as guys who play pro ball, for sure.
What you can do to help your reactions is to be relaxed.
People who are tense, nervous and allow things to take them by surprise aren't able to react quickly.
Be "mentally rehearsed" about all your hand movements while starting the engine and with every part of the flight.
Learn from things that go wrong. Things go wrong with me and everyone else.
If your plane is set up mechanically for mild control response you don't need "super powers" to fly fast planes.
If the controls are set up too aggressively [like 3D settings], then a high speed plane will tend to be hard to control and you will blame yourself for having "slow reactions".


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RE: Aother DELTA wing airfoil question - 2/11/2013 1:53 AM   
MJD



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Status: offline 		What I always say is that you should see the flight path in your mind before you get there. Imagine a built in HUD screen and on it in front of your eyes to follow is your big oval flight path, or your figure 8 pattern, or a 45 climb, half-loop then half-roll turnaround maneuver at each end*, or whatever feels natural to you. Your thumbs will follow if you already know where you want to go. If you are constantly improvising the flight path and fretting about "oh geez, now what? OMG this thing is fast, left or right, what do I do now??" you will be under too much stress and the airplane will feel wayyy faster than it really is.

When you get comfortable with the aircraft, then you can just do whatever you want as you fly.

I remember my first flight with a Magnum R, I had the throws way too high and it was twitchy and jumpy and was just a total be-yatch. Before recovering my composure and snapping on a gentler flight mode I botched a turnaround after flying wayyyyyy too far down range, and ended up disoriented and going the wrong way at full tilt. How I got it turned around again I am not sure, but all I remember is that I finally realized it was getting bigger again.. and that was a good thing so I just waited it out. Not sure why I forgot about the throttle either, panic I suppose. Just goes to support CP's theory that you don't really need one, I suppose.


* Some article in a M.A.N. in the bathroom magazine rack says it's called a reverse laydown humpty-bump or something like that. Easier to fly it than name it.

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RE: Aother DELTA wing airfoil question - 2/11/2013 2:14 AM   
Jaspur_x


 

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From: Friedens, PA, USA
Status: offline 		I usuallu fly in limited space and thats why my control surfacesand settings  lean toward the Clancy lazybee style designs even when I`m not flying a Clancy designed plane.
It doesnt help me out a whole lot as you`ve seen on my video,I need to get back into a slow flyer like a salplane to get the "rusty thumbs" condition to clear up lol

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RE: Aother DELTA wing airfoil question - 2/14/2013 12:47 AM   
Jaspur_x


 

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From: Friedens, PA, USA
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quote:

ORIGINAL: MJD

What I always say is that you should see the flight path in your mind before you get there. Imagine a built in HUD screen and on it in front of your eyes to follow is your big oval flight path, or your figure 8 pattern, or a 45 climb, half-loop then half-roll turnaround maneuver at each end*, or whatever feels natural to you. Your thumbs will follow if you already know where you want to go. If you are constantly improvising the flight path and fretting about "oh geez, now what? OMG this thing is fast, left or right, what do I do now??" you will be under too much stress and the airplane will feel wayyy faster than it really is.

When you get comfortable with the aircraft, then you can just do whatever you want as you fly.

I remember my first flight with a Magnum R, I had the throws way too high and it was twitchy and jumpy and was just a total be-yatch. Before recovering my composure and snapping on a gentler flight mode I botched a turnaround after flying wayyyyyy too far down range, and ended up disoriented and going the wrong way at full tilt. How I got it turned around again I am not sure, but all I remember is that I finally realized it was getting bigger again.. and that was a good thing so I just waited it out. Not sure why I forgot about the throttle either, panic I suppose. Just goes to support CP's theory that you don't really need one, I suppose.


* Some article in a M.A.N. in the bathroom magazine rack says it's called a reverse laydown humpty-bump or something like that. Easier to fly it than name it.


Soooo thats what I have always done wrong,I never planned out any flight path after the take off run away from the airplane eating trees. My usual 2 flight fields are @ my house 40 yards from my front door(take off point)  is the end of my front yard and 60 ft. tall and up  trees, x 40 yards to more trees and a road.
@ my dads house, 60 yards from take off point to very large trees x 600 yards but this location happens to have the long side in cross wind so I always take off aiming @ the short run into the trees if I can`t climb or turn 90degrees.
My littlest stick always was a favorite @ dads house but last time I tried flying there it was only a 20 second flight with my mock stick,which is a modified littlest stick design of course: 26" span based on an extended littlest stick wing plan, fuse is wider and taller top to bottom than littlest stick and a few inches longer overall. I run a really detuned black widdow on that.

My rusty thumbs can`t even keep up with my blade mcpx heli anymore but the msr is not beyond my skill level lol

I may have to regress all the way back to a powered sailplane like my COX ezbee GASP AND EEEGADS MAN !!!!!!


But getting back to deltas, are you getting the idea that after take off and attaining a suitable elevation agl I be needing to throttle back to "its just fast enough to keep on actually flying instead of falling from the sky" or it will become gravity fodder lol
And on the 010`s limited fuel supply, lets just say mine runs more like 4 -5 minutes than stock fuel tanked engines.  

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