funkydrummermike

Hello,

I pucked this wing up at an auction and the seller didn't have any information for me. I am trying to find out who the manufacturer of this kit/arf is. It's a .40 size, I am quessing. Wingspan is 39.5". I'd like to know who the manufacturer is so maye I could get their recommendations for CG and control throws. I am sure I could figure it out on my own, but I thought it would be easier to have their information because I would like to get more then one take-off with it. Anyways, let me know what it is if you can.

Thanks,
Mike

mk1spitfire

maybe a laser arrow???????????

soarrich

My Feedback: (98)

Somebody went to the JCSF auction.

I think the other guy is right, it also came with a stupid tiger color scheme.

Hey it's a delta, go 1/3 of the span out the 30% for the CG, use as much elevator as you can get, start with 1/4" ailerons with some expo.

This is what it looked like before it was stripped. I haven't flown mine yet, it had RF off my carb linkage and got set aside.

MJD

My Feedback: (1)

I have a Laser Arrow partly built and it doesn't look like that.

Is that an ST-X .45 on the front of that?

MJD

airraptor

My Feedback: (66)

when you set it up i believe you need some up trim preset into the delta. maybe like 3-5 degrees

soarrich

My Feedback: (98)

.40 I think. I got it for almost nothing because it didn't run, it had a little piece of metal by the alinement noch in the cylinder top. 1500 grit wet/dry and a piece of glass, 10 seconds of work fixed it. I was getting RF of the metal to metal carb linkage, a ball link will fix it, then I fly it.

tIANci

Anyone noticed almost all deltas need up trim ... anyone knows why?

soarrich

My Feedback: (98)

All pure flying wings need reflex or sweep, up trim provides reflex.

Mike Connor

My Feedback: (5)

Mine don't need up trim, if they are balanced correctly.

mk1spitfire

Is a flying wing different from a true Delta.?

Flying wings need some reflex to hold the attitude

mk1spitfire

laser arrow

soarrich

My Feedback: (98)

Yep, that was the other color scheme I was offered.

soarrich

My Feedback: (98)

Or:

Is a Delta different from a true flying wing?

A delta is a true flying wing, with a straight trailing edge, and a highly swept highpoint of the airfoil, but i don't think there is enough sweep to eliminate the need for reflex.

soarrich

My Feedback: (98)

Then they fly inverted with out holding in down? I bet not. If your delta is a symmetrical section and doesn't need up trim, I would say that is because all the drag producing stuff is setting on the top of the wing pulling the nose up with drag.

mk1spitfire

My Weston uk Tigershark Delta has no aerofoil, its a flat section.

BaldEagel

It must have been something you ate. [:'(]

Mike

Mike Connor

My Feedback: (5)

The delta is symmetrical and mine is I set up so I need a very slight back pressure at speed to hold altitude. When inverted it needs very slight forward pressure to maintain altitude. So I guess what you are saying is true but the elevon deflection needed for level flight is not obvious when looking at it, when the CG is correct.

soarrich

My Feedback: (98)

Yes, dealts can fly without airfoils. There's many ways to make lift, a delta can use an airfoil, or vortex generated lift.
Here's some of mine:
First is the Vortex.
Second is a Diamond Dust.
Third is the Laser Arrow.
Forth to sixth is my NACA delta.
Seventh thru ninth is my Shully Delta.

The Vortex uses an airfoil to make lift upto about 15* AoA, then vortex generated lift.
The DD uses vortex lift and it's motor to make lift.
The Arrow is the same as the Vortex, just on a smaller scale.
The NACA delta makes lift with vortex genterated lift and 67,000 rpm 3x3 prop, 275 watts of power.
The Shully Delta makes it's lift with vortex generated lift. If you look closely you'll see it's really got a flat bottom airfoil UPSIDE DOWN.

MJD

My Feedback: (1)

If the airfoil is generating lift, then there is a pitching moment, and there must be a stabilizing force to counteract the pitching moment. It might not be visually obvious, it's just that at high speeds the required lift coefficient is low, so the angle of attack is very low and thus the elevon deflection very small. But it is there, and it is needed, unless the airfoil has reflex in order to generate that force without deviation from the airfoil profile via control surface deflection, or a twist is incorporated into the wing - same deal different wrapping paper. If it is trimmed for level flight at speed with no stick pressure, no way is it trimmed for inverted level flight at the same time.

MJD

funkydrummermike

Cool, thanks for the info. It's always interestign how a post morphs into a different thread.

ha ha ha ... yeah I pucked it up. I bought it with covering but was hungry after the auction and that's what it looked like when I was done spewing it out. yes, I did get it at the JCSF auction. One hole in the head is never enough.

Mike

Mike Connor

My Feedback: (5)

On a symmetrical delta your should be able to move the CG so a centered elevon would be level flight. When this is achieved then rolling it inverted should produce the same results, level flight.

MJD

My Feedback: (1)

Really? Okay, I'll buy that.. but it sounds like a pretty critical CG position. Isn't the CG getting nervously close to the NP in that trim config?

MJD

funkydrummermike

A wing generates lift by creating a pressure differential. A symmetrical airfoil, by its very nature, does not generate pressure differential at zero angle of attack. If a symmetrical wing were to fly at zero angle of attack, it would not generate lift and eventually fall to the ground, regardless of forward speed. Gravity is constantly pulling the plane down; lift must be generated to counteract that force. The only way a symmetrical wing can maintain level flight is by increasing the angle of attack. By changing the angle of attack, you are effectively changing the airfoil. By changing the airfoil through angle of attack, the "symmetrical" airfoil is now creating a pressure differential, otherwise known as lift. If the control surfaces were trimmed for true zero input, so that they are parallel with the datum line, the wing would have zero angle of attack and the plane would not be able to maintain level flight. Therefore maintaining level flight with the plane right side up will require up elevator and down elevator to maintain level flight while inverted. Or what MJD said.

Mike Connor

My Feedback: (5)

With a forward CG it would require a lot of up elevator to maintain level flight. When inverted it would also require a lot of down (actually up) elevator to maintain level flight. Forgetting stability issues, you could move the the CG far enough back so opposite controls would be required for level flight. There would have to be a balance point where a nutral elevon would produce level flight and a symmetrical airfoil would not know the difference if it was inverted.

Mike Connor

My Feedback: (5)

The slightly aft CG location would give it the angle of attack needed for level flight regardless if it was up side down or not.