Flying without a vertical stabilizer

[Piotrsko]

All airfoils require some sort of angle of attack device to generate lift, symmetric ones need couple degrees more possibly because the flat bottom that increases pressure is changed into a streamlined surface with a negative lift coefficient. Paper napkin engineering, could be wrong. Been so long since I built a wing with washout, I had to think about what it was. Washout should only affect tip stalls which can cause terminal death dive into the dirt, typically the stalled wing tip impacting first. On reflex, if the wing is making lift, the reflex is causing some drag. On a swept wing, that drag is typically behind the CG even if it has full trailing edge surfaces. Same as a straight wing, only less stabilizing effect because it's not as far from the CG. CANARDS are a whole different animal because the lifting surfaces aren't anywhere near the CG.

 

[L Edge]

All airfoils require some sort of angle of attack device to generate lift, symmetric ones need couple degrees more possibly because the flat bottom that increases pressure is changed into a streamlined surface with a negative lift coefficient. Paper napkin engineering, could be wrong. Been so long since I built a wing with washout, I had to think about what it was. Washout should only affect tip stalls which can cause terminal death dive into the dirt, typically the stalled wing tip impacting first. On reflex, if the wing is making lift, the reflex is causing some drag. On a swept wing, that drag is typically behind the CG even if it has full trailing edge surfaces. Same as a straight wing, only less stabilizing effect because it's not as far from the CG. CANARDS are a whole different animal because the lifting surfaces aren't anywhere near the CG.

I tend to do my experimental stuff from summation of forces(3 axis) gives stability in flight.
Got the EZ Pack (has only throttle and differential thrust) where 1/2 throttle gives level flight where you move the cg to0 match throttle, more thrust makes it climb, and less thrust gives it a glide slope.
So i decided to do a B2 Spirit.
Ended up putting 1 1/2 degrees of reflex behind prop flow and now my summation of forces gives stability.

Here is a video to prove it flies. After adding and adjusting the reflex(same battery) it works, and its too bad the battery crapped out for glide slope ain't too bad with thrust off. I also added another trick to it to make it work for summation of forces equal zero.

 

[L Edge]

Gut says inward is nose up effect, outward is down or zero even if they are plumb to the wing. I can see up being useful, down, not so much but could be a trim effect. Yeah it's primarily for hopefulley making drag aft of the CG,

Need picture, having a dyslexia moment.

Go to this site for update.

Trying 2 ideas for Rudderless NYGAD plane

Both @telnar1236 and myself are working on different concepts to design a rudderless plane that needs no gyro or flight controller. My first idea is an offshoot of my X-47B and the second is a radical approach that I put together. Working from the unknown, why waste time designing a plane. So...

forum.flitetest.com

 

[telnar1236]

All airfoils require some sort of angle of attack device to generate lift, symmetric ones need couple degrees more possibly because the flat bottom that increases pressure is changed into a streamlined surface with a negative lift coefficient. Paper napkin engineering, could be wrong. Been so long since I built a wing with washout, I had to think about what it was. Washout should only affect tip stalls which can cause terminal death dive into the dirt, typically the stalled wing tip impacting first. On reflex, if the wing is making lift, the reflex is causing some drag. On a swept wing, that drag is typically behind the CG even if it has full trailing edge surfaces. Same as a straight wing, only less stabilizing effect because it's not as far from the CG. CANARDS are a whole different animal because the lifting surfaces aren't anywhere near the CG.

Makes sense. Not sure about how much reflex would help on a straight wing with yaw stability since it's how much the restoring moment changes with sideslip angle that determines stability, but for swept wings that seems reasonable.

 

[telnar1236]

Good news and bad news. The bad news is that the plane does not fly in its current state and that I didn't get video. The good news is that none of the problems are related to it being a tailless design finally and that it's intact enough to repair and fix the issues. L Edge was completely right about the EDF nozzle design. While it glides well, as soon as power is applied it wants to pitch up hard. I was able to just about trim it by having the elevator deflected fully down, but so much as touching it made the plane cobra. However, the spoilers worked ok and there were a couple times I was able to get brief roll control until the plane did a backflip. Moving forwards, I plan to change the nozzle so that it is more conventional and add a bit of nose weight to move the CG forward and then I think it will fly

 

[Piotrsko]

Reflex on straight wing works, otherwise you wouldn't have plank flying wings, it's just inefficient but then the planks main advantage is ease of build.. as I said before, sometimes planks fly sideways.
Why wouldn't you want to add down thrust like a prop powered plane? Nozzle placement below the center of mass makes it nose up

 

[badpilot27]

Makes sense. Not sure about how much reflex would help on a straight wing with yaw stability since it's how much the restoring moment changes with sideslip angle that determines stability, but for swept wings that seems reasonable.

I think you should keep looking at large amounts of wing twist to get the prandtl bell shaped lift distribution to manipulate thrust at the wing tips to achieve lateral stability. I know its pretty hard to do at low aspect ratios but I think it is possible. only big problem is that your elevons should make up only 30% of the span of the wing so that it effectively manipulates the induced thrust at the wing tips. having a larger elevon would result in the same problems that the hortens faced on their flying wings where the large elevon would cause it to still have adverse yaw despite the induced thrust generated at the wing tips.

 

[L Edge]

The other interesting point that I would like to make is the problems dealing with a single EDF are different that a design of 2 EDF's. It is more complicated(Dark Star had one set to get it to fly(has fixed rudder) as well as being unresolved without rudder(NYGAD version) as of now.

 

[telnar1236]

I think you should keep looking at large amounts of wing twist to get the prandtl bell shaped lift distribution to manipulate thrust at the wing tips to achieve lateral stability. I know its pretty hard to do at low aspect ratios but I think it is possible. only big problem is that your elevons should make up only 30% of the span of the wing so that it effectively manipulates the induced thrust at the wing tips. having a larger elevon would result in the same problems that the hortens faced on their flying wings where the large elevon would cause it to still have adverse yaw despite the induced thrust generated at the wing tips.

I have experimented with wing twist up to 10 degrees, and simply put on this planform, the wing twist is not sufficient to create induced thrust and counter adverse yaw while maintaining fighter-like roll rate and pitch control. Reducing the size of the elevons would help reduce adverse yaw, like you say, but would not result in a fast-responding fun-to-fly plane.

 

[telnar1236]

On to the next version! Again! Unfortunately, the revised ducting meant the plane didn't really have enough thrust, and it was still tail heavy. I ended up taping a rock from the field to the nose to achieve CG after a few unsuccessful launches, but by then the wings were kind of floppy and losing their shape. I did get a couple of long flights in a straight line or gentle curve (not caught on video unfortunately) but I think the spoilers were too small, especially when paired with extra play introduced by repeated crashes so while I did have roll control, I didn't have much of it and could not counter even light gusts of wind fast enough to keep the plane in the air for long. With the floppy wings, the plane had dihedral once flying instead of the intended anhedral, so it probably had improved lateral stability but much worse directional stability relative to what it should have had.

 

[Mr Man]

On to the next version! Again! Unfortunately, the revised ducting meant the plane didn't really have enough thrust, and it was still tail heavy. I ended up taping a rock from the field to the nose to achieve CG after a few unsuccessful launches, but by then the wings were kind of floppy and losing their shape. I did get a couple of long flights in a straight line or gentle curve (not caught on video unfortunately) but I think the spoilers were too small, especially when paired with extra play introduced by repeated crashes so while I did have roll control, I didn't have much of it and could not counter even light gusts of wind fast enough to keep the plane in the air for long. With the floppy wings, the plane had dihedral once flying instead of the intended anhedral, so it probably had improved lateral stability but much worse directional stability relative to what it should have had.

Why don’t you try thrust vectoring instead of rudders?

 

[telnar1236]

Why don’t you try thrust vectoring instead of rudders?

Thrust vectoring only works so long as you have thrust. I want this thing to be able to glide. The control surfaces aren't really rudders. They're spoilers, to control roll, kind of like what you see on many supersonic fighters like the F-111 or mirage F1. They're not as good as ailerons at subsonic speeds, but they should work and do what I want.

I just need to get better at designing and building them (and maybe mix in elevons again). I sized them by gut feeling and made them pretty small out of fear of over controlling the plane, but looking at these pictures, I made them far too small. Despite running into so many problems, I'm actually pretty happy with the concept I have and think that it's mostly a matter of minor tweaks to get it flying at that this point.

 

[Mr Man]

👍

 

[L Edge]

On to the next version! Again! Unfortunately, the revised ducting meant the plane didn't really have enough thrust, and it was still tail heavy. I ended up taping a rock from the field to the nose to achieve CG after a few unsuccessful launches, but by then the wings were kind of floppy and losing their shape. I did get a couple of long flights in a straight line or gentle curve (not caught on video unfortunately) but I think the spoilers were too small, especially when paired with extra play introduced by repeated crashes so while I did have roll control, I didn't have much of it and could not counter even light gusts of wind fast enough to keep the plane in the air for long. With the floppy wings, the plane had dihedral once flying instead of the intended anhedral, so it probably had improved lateral stability but much worse directional stability relative to what it should have had.

Maybe you should name this plane "Rock On"

 

[telnar1236]

Maybe you should name this plane "Rock On"

That's an amazing idea

 

[Mr Man]

Thrust vectoring only works so long as you have thrust. I want this thing to be able to glide. The control surfaces aren't really rudders. They're spoilers, to control roll, kind of like what you see on many supersonic fighters like the F-111 or mirage F1. They're not as good as ailerons at subsonic speeds, but they should work and do what I want.
View attachment 246512
View attachment 246513
I just need to get better at designing and building them (and maybe mix in elevons again). I sized them by gut feeling and made them pretty small out of fear of over controlling the plane, but looking at these pictures, I made them far too small. Despite running into so many problems, I'm actually pretty happy with the concept I have and think that it's mostly a matter of minor tweaks to get it flying at that this point.

So this is a spoiler alert?

😅😂🤣

 

[Flying Cherokee]

So this is a spoiler alert?

😅😂🤣

Ha Ha Ha....
(just kidding)

 

[telnar1236]

A spoiler alert indeed