Kryptonizers (movable SFGs)

[Glenn carter]

Moveable Side Force Generators! I have been developing moveable SFGs, they are approx half the size with less side effect, as much power and some extra functions. They are operated with independant servos and mixed first with rudder. In its most simple form eg.right rudder toes out the LE of the right SFG using free mix and not the left, reverse for left rudder. The next is a throttle mix that toes in both SFGs on low throttle for down line braking, this is also used on a landing switch as airbrakes. They give vastly improved knife edge stability, more progressive transitions on rolling manouvers ( knife edge loop stability grouse! ) all without the negative effects of fixed SFGs eg crosswind performance, in the air there the only input required is the air brake for landing, the rest is done thru mixing and there are some tips to the use of expo and the percentage one moves in relation to the other, but will go into that if anyone is interested
May the side Force be with you! Boomshanka

[Ollie]

Why doesn't Superman use kryptonizers? How does Superman reacelerate? Why don't planes use negative thrust rather than SFD's? Do plane's mount the thrust generators on gimbals? On and on?????????.

[Bill K.]

Moveable Side Force Generators! I have been developing moveable SFGs, they are approx half the size with less side effect, as much power and some extra functions. They are operated with independant servos and mixed first with rudder. In its most simple form eg.right rudder toes out the LE of the right SFG using free mix and not the left, reverse for left rudder. The next is a throttle mix that toes in both SFGs on low throttle for down line braking, this is also used on a landing switch as airbrakes. They give vastly improved knife edge stability, more progressive transitions on rolling manouvers ( knife edge loop stability grouse! ) all without the negative effects of fixed SFGs eg crosswind performance, in the air there the only input required is the air brake for landing, the rest is done thru mixing and there are some tips to the use of expo and the percentage one moves in relation to the other, but will go into that if anyone is interested
May the side Force be with you! Boomshanka

Sounds neat, but as we say in my primary hobby these days... without video, it didn't happen...!! ;) So lets see the video man. :)

[nmasters]

On flying wings we call those drag rudders :D

[MacYankee]

Interesting ideas. Would be neat to experiment with... :rolleyes:
Gordon

[Glenn carter]

On flying wings we call those drag rudders :D
Not like drag rudders at all. as soon as I figure how to att pic you will understand. Glenn

[nmasters]

Well, "drag rudder" just refers to any device that increases drag at or near the tip with the intention of producing a yawing moment.

When you use the "New Reply" or "Quote" button there is a section below the message input window labeled "Additional Options". The "Manage Attachments" button in additional options opens a fairly easy upload dialog. Just remember to hit the "Upload" button before you close that dialog or you won't upload anything.

--Norm

[yoyoML]

Heehee, you're two years late, buddy!

http://www.pixnet.net/photo/homeboywu/7181823

See the purple part trailing the SFG? They share the rudder servo through the horizontal cf rod. I used to call them siderons. That was Christmas 04 and it's still in flying condition today!

Why do you only mix the right SFG to right rudder? Why not both SFG all the time?

[Glenn carter]

Heehee, you're two years late, buddy!

http://www.pixnet.net/photo/homeboywu/7181823

See the purple part trailing the SFG? They share the rudder servo through the horizontal cf rod. I used to call them siderons. That was Christmas 04 and it's still in flying condition today!

Why do you only mix the right SFG to right rudder? Why not both SFG all the time?

You miss the point the secret to the the whole idea is the use of separate multi point mixes

[Azarr]

You miss the point the secret to the the whole idea is the use of separate multi point mixes

I'd like to hear more about your mix.

Azarr
www.ecubedrc.com

[yoyoML]

I'd like to hear more about your mix.

Azarr
www.ecubedrc.com

Me, too.

Besides using SFG as brakes, I can't see how it'd help otherwise?

[Glenn carter]

Me, too.

Besides using SFG as brakes, I can't see how it'd help otherwise?
I will make time to write the whole process and post it until then something to think about. imagine the model in knife edge, right rudder using multi piont mix and say 50% expo on rudder you use a steep curve on SFG that flattens so a small rudder deflection gives almost full defection of SFG TE towards fuz(about 8deg) for the right and (4deg )TE away from fuz for the left in rudder mode. now fly thru a knife edge loop, the right SFG is working harder than left giving extra side force and stability, this applies to rolls, circles and even laying off wind. Its very hard to explain in a few words I HOPE this gets you thinking. Glenn

[yoyoML]

I will make time to write the whole process and post it until then something to think about. imagine the model in knife edge, right rudder using multi piont mix and say 50% expo on rudder you use a steep curve on SFG that flattens so a small rudder deflection gives almost full defection of SFG TE towards fuz(about 8deg) for the right and (4deg )TE away from fuz for the left in rudder mode. now fly thru a knife edge loop, the right SFG is working harder than left giving extra side force and stability, this applies to rolls, circles and even laying off wind. Its very hard to explain in a few words I HOPE this gets you thinking. Glenn

Which kind of stability does the right SFG provide, during the knife edge loop you describe? Is it roll or yaw stability?

What kind of stability does it offer in a roll?

[Glenn carter]

Which kind of stability does the right SFG provide, during the knife edge loop you describe? Is it roll or yaw stability?

What kind of stability does it offer in a roll?
I guess the easiest way to describe the knife edge stability is pendulum stability a little like it being suspended by the wingtip. But there is more to it than that, in rolling rudder prduces the required side force for knife edge via fuz attitude, these require less fuz attitude for level flight hence smoother transitions during rolling manouvers at a slower and more constant speed, I think they will even give greater results on a F3A model, my current project. Glenn

[yoyoML]

I guess the easiest way to describe the knife edge stability is pendulum stability a little like it being suspended by the wingtip.

This pendulum stability doesn't exist. The reason is simple: the wing tip exerts no rolling torque at all. The force from the SFG passes right through CG (height-wise) so there's no moment arm. A pendulum returns to center because gravity exerts a restoring torque (around the hinge point) whenever the pendulum is not centered.

Think about hovering in 3D flying. You'd think that with all the plane's weight hanging below the pulling prop at top, a hover is stable. But in fact since the prop (thrust it generates) exerts no yawing or pitching torque, there's no stability from the thrust at all. Ask any 3D pilot if hovering is a hands-off lazy job!

But there is more to it than that, in rolling rudder prduces the required side force for knife edge via fuz attitude, these require less fuz attitude for level flight hence smoother transitions during rolling manouvers at a slower and more constant speed, I think they will even give greater results on a F3A model, my current project. Glenn

Indeed you'll need less yaw AoA for knife edges or during rolls, it may help at rolling. Beware of a hidden problem, though: as you add SFG's, you move the yaw neutral point forward and will likely reduce yaw stability. This reduced yaw stability may prevent the nose from following flight path after a hammerhead, or after any high yaw AoA maneuver.

For the same reason, during a normal banking turn, the plane won't eagerly turn (yaw) in the direction of the bank. You WILL HAVE TO add rudder to make a banking turn, which you may not need without SFG's. For example, the Tensor 4D I posted will not turn at all if I only rolled it. It simply flies straight banked to one side. You won't get anything as dramatic, because the Tensor's side area is almost as large as its wing area. Just don't be surprised, anyway.

[Glenn carter]

This pendulum stability doesn't exist. The reason is simple: the wing tip exerts no rolling torque at all. The force from the SFG passes right through CG (height-wise) so there's no moment arm. A pendulum returns to center because gravity exerts a restoring torque (around the hinge point) whenever the pendulum is not centered.

Think about hovering in 3D flying. You'd think that with all the plane's weight hanging below the pulling prop at top, a hover is stable. But in fact since the prop (thrust it generates) exerts no yawing or pitching torque, there's no stability from the thrust at all. Ask any 3D pilot if hovering is a hands-off lazy job!



Indeed you'll need less yaw AoA for knife edges or during rolls, it may help at rolling. Beware of a hidden problem, though: as you add SFG's, you move the yaw neutral point forward and will likely reduce yaw stability. This reduced yaw stability may prevent the nose from following flight path after a hammerhead, or after any high yaw AoA maneuver.

For the same reason, during a normal banking turn, the plane won't eagerly turn (yaw) in the direction of the bank. You WILL HAVE TO add rudder to make a banking turn, which you may not need without SFG's. For example, the Tensor 4D I posted will not turn at all if I only rolled it. It simply flies straight banked to one side. You won't get anything as dramatic, because the Tensor's side area is almost as large as its wing area. Just don't be surprised, anyway.
I am very familiar with the tensor and have a great deal of time on them, and know exactly what you are talking about. The model I fitted these to had been flying for over a year before they were fitted and its flight charecteristics well explorered. With most models in the case of a knife edge loop the last quarter is where the quirks arrise, these transfomed this model, there is a slight benifit with them fitted but turned off normal SFG but the stabilty is not there. As for stall turns there is no problem, as for spins, the entrys are better if anything. Dont forget on a closed throttle the toe in slightly giving increased yaw stability. Glenn

[yoyoML]

With most models in the case of a knife edge loop the last quarter is where the quirks arrise, these transfomed this model, there is a slight benifit with them fitted but turned off normal SFG but the stabilty is not there. As for stall turns there is no problem, as for spins, the entrys are better if anything. Dont forget on a closed throttle the toe in slightly giving increased yaw stability. Glenn

Ahh, I see. As I said the harder working top SFG gives no stability whatsoever, but indeed the last quarter of a K.E. loop should work better, for another reason.

Simply you need less yaw AoA to get the same amount of side lift. The original difficulty in a K.E. loop is that with high yaw AoA, half of the main wing is way ahead of the other half. The tendency to roll out is just the classical yaw-roll coupling: if you pulled/pushed even a little elevator the coupled roll would be huge due to the high yaw AoA. Now, reducing required yaw AoA does make the wing halves travel equally, reducing some coupling.

But then, this doesn't need SFG differential at all. In fact it'd be better if they were hard linked to the same deflection. One SFG working hard is worse than two SFG's working half as hard, right? Besides, the toe-out reduces yaw stability.

As for toe-in when throttle off. I think you'll need to consider very carefully if the stability is increased or not. Two forces (torques) oppose here. One is the lift from the SFG's. The other is the drag differential from the toe-in and a slight yaw AoA. If the former is larger then yaw is less stable than without SFG's. These depend on the placement of SFG's greatly so you'll have to measure and calculate.

Better spin entry was to be expected, due to the lower yaw stability plus the inner SFG drag.

I just think you aren't gaining too much from the cost/complexity/weight of one more servo. ;)

[Glenn carter]

Ahh, I see. As I said the harder working top SFG gives no stability whatsoever, but indeed the last quarter of a K.E. loop should work better, for another reason.

Simply you need less yaw AoA to get the same amount of side lift. The original difficulty in a K.E. loop is that with high yaw AoA, half of the main wing is way ahead of the other half. The tendency to roll out is just the classical yaw-roll coupling: if you pulled/pushed even a little elevator the coupled roll would be huge due to the high yaw AoA. Now, reducing required yaw AoA does make the wing halves travel equally, reducing some coupling.

But then, this doesn't need SFG differential at all. In fact it'd be better if they were hard linked to the same deflection. One SFG working hard is worse than two SFG's working half as hard, right? Besides, the toe-out reduces yaw stability.

As for toe-in when throttle off. I think you'll need to consider very carefully if the stability is increased or not. Two forces (torques) oppose here. One is the lift from the SFG's. The other is the drag differential from the toe-in and a slight yaw AoA. If the former is larger then yaw is less stable than without SFG's. These depend on the placement of SFG's greatly so you'll have to measure and calculate.

Better spin entry was to be expected, due to the lower yaw stability plus the inner SFG drag.

I just think you aren't gaining too much from the cost/complexity/weight of one more servo. ;)
A Ponder.... In your opinion what would be the result of performing the same KE loop with only the inboard SFG fitted?

[yoyoML]

A Ponder.... In your opinion what would be the result of performing the same KE loop with only the inboard SFG fitted?

The same as you now have, plus some yaw stability and a non-zero yaw equilibrium AoA.

Didn't give assymetrical things too much thought, though...