Trim Question on inside loops..

[Joe Yau]

I had this problem before many years ago with a different plane, and have forgotten how it was solved.   It is the Inside loop going tight about half way through.. especially in the wind or faster lap speed.  sort of looking like the lower case "e"  Just wondering what would cause this? and what would help reduce this effects.

Thanks in advance.

[Brett Buck]

I had this problem before many years ago with a different plane, and have forgotten how it was solved.   It is the Inside loop going tight about half way through.. especially in the wind or faster lap speed.  sort of looking like the lower case "e"  Just wondering what would cause this? and what would help reduce this effects.

Thanks in advance.

   Tail heavy.

    Brett

[Joe Yau]

   Tail heavy.

    Brett

But it's already towards the nose heavy side.  anything else?

[Brett Buck]

But it's already towards the nose heavy side.  anything else?

  If it is tightening up in maneuvers, it is tail-heavy, this is a classic symptom.

    If it is doing it strictly in the wind, you may be putting in too much bias.

     Brett

[Joe Yau]

  If it is tightening up in maneuvers, it is tail-heavy, this is a classic symptom.

    If it is doing it strictly in the wind, you may be putting in too much bias.

     Brett

Thanks Brett.  I'll try some more nose weight and see if that works. 

not sure what you're referring to on the biasing.

[Brett Buck]

Thanks Brett.  I'll try some more nose weight and see if that works. 

  If, after you get some change there, it starting becoming too heavy/comes out low on outside round loops, you probably want to start putting in small amounts of down elevator at neutral flap until it is the same, both ways.

     If it then feels to heavy or too light in the round loops, you can play off the nose weight VS the flap/elevator ratio. That one you have to decide for yourself. Adding noseweight and adding flap travel have similar effects on the conntrol pressure, but a *tiny* change in the flap/elevator ratio can have a very large effect.

not sure what you're referring to on the biasing.

    If you are biasing the maneuvers into the wind, you are doing it too far - i.e. the inside loops are being biased too far to the left. This is a classic technique to try to relieve control pressure from wind-up, but it is very easy to overdo it with current engines, and have the bottoms float up. Put the maneuver closer to dead downwind. You can use the same effect to overcome trim issues in a pinch, in your case, with the effect you describe, I would shift the inside loops to the right.

     Brett

[Ted Fancher]

Brett,

He hasn't told you what ship it is.  If it isn't flapped you might also want to check on any handle bias/where he holds in hand in level flight, etc. and, especially, find out what it does in outside loops which might be valuable re evaluating CG location vice trim/set-up issues.

Ted

[Joe Yau]

  If, after you get some change there, it starting becoming too heavy/comes out low on outside round loops, you probably want to start putting in small amounts of down elevator at neutral flap until it is the same, both ways.

The nose weight didn't seems to help the inside round other then made the control heavier on corners. I started with .6 oz, then 1 oz. I think it made the outside round more consistent but not insides.

     If it then feels to heavy or too light in the round loops, you can play off the nose weight VS the flap/elevator ratio. That one you have to decide for yourself. Adding noseweight and adding flap travel have similar effects on the conntrol pressure, but a *tiny* change in the flap/elevator ratio can have a very large effect.

The CG is close with the amount of flap deflections. I might try slightly less flaps and forward CG.

 

   If you are biasing the maneuvers into the wind, you are doing it too far - i.e. the inside loops are being biased too far to the left. This is a classic technique to try to relieve control pressure from wind-up, but it is very easy to overdo it with current engines, and have the bottoms float up. Put the maneuver closer to dead downwind. You can use the same effect to overcome trim issues in a pinch, in your case, with the effect you describe, I would shift the inside loops to the right.

     Brett

O.k. that makes sense, and I have encountered that a few times.  I'll try that next time. 

At the field today.. Chris Cox suggested I try moving the up line LO forward. (down line is in front, so they're closer together)   so I moved it about 1/8"forward..    and unexpectedly it did seems to helped.  It gave me more solid feel on the path from a little pass the top on down without going tight.  I will have to retest this next time out. as I was on my last battery.  and couldn't verified this on another flight.

[Joe Yau]

Brett,

He hasn't told you what ship it is.  If it isn't flapped you might also want to check on any handle bias/where he holds in hand in level flight, etc. and, especially, find out what it does in outside loops which might be valuable re evaluating CG location vice trim/set-up issues.

Ted

Hi Ted,  The plane is a Brodak Legacy. Electric (AXI 2826-12 on 5 cells)  with Active Timer etc.

[Ted Fancher]

Few more questions, Joe.
A. Airplane trim:
1. Are the wings level upright and inverted per Chris?
2. Do the inside loops on the figure eight maneuvers have the same problem?
3. Same quest re the insides of the four leaf clover.
4. Is the vertical climb in the clover reliably vertical or does it climbs slightly inverted (to your right) and need to be corrected back to vertical?
5. In level flight how much of the outboard wheel can you see in front of or behind the inboard wheel in level flight? (Be sure to check first that they are aligned with one another on the ground.)
6. Is the airplane easily controlled and "whip-able" in the glide?
7. How far apart are the leadouts at the wingtip and how far behind the CG is the midpoint of the leadouts when the ship is held balanced on your fingers at the wingtips?
8. Does the prop spin right hand rotation or left hand ("pusher")

B. Pilot trim.

1.Where do you hold your "flying" hand in level flight upright and inverted in the vertical axis; i.e. shoulder high? chest high? belt high? below the belt? (hint, ask Chris for an observer's perspective).
2. Do you generally make the inside and outside loops the same size in the figure eights and clover or are the insides usually smaller than the outsides?
3. When you check for neutral after hooking up your lines are the attachment points of the up and down lines directly above one another?
4. With the flaps and elevators in neutral during the pre-flight control check is the handle grip vertical or is it tilted forward in the "relaxed, handshake grip" some flyers (incorrectly IMHO) prefer?

Whew!  That'll teach you to ask, huh? 

Ted

[goozgog]

I'm really enjoying this exchange.

  I flew yesterday and I'm mentally applying
these checks to those flights.

Thanks gentlemen.

[Joe Yau]

Few more questions, Joe.
A. Airplane trim:
1. Are the wings level upright and inverted per Chris?
2. Do the inside loops on the figure eight maneuvers have the same problem?
3. Same quest re the insides of the four leaf clover.
4. Is the vertical climb in the clover reliably vertical or does it climbs slightly inverted (to your right) and need to be corrected back to vertical?
5. In level flight how much of the outboard wheel can you see in front of or behind the inboard wheel in level flight? (Be sure to check first that they are aligned with one another on the ground.)
6. Is the airplane easily controlled and "whip-able" in the glide?
7. How far apart are the leadouts at the wingtip and how far behind the CG is the midpoint of the leadouts when the ship is held balanced on your fingers at the wingtips?
8. Does the prop spin right hand rotation or left hand ("pusher")

B. Pilot trim.

1.Where do you hold your "flying" hand in level flight upright and inverted in the vertical axis; i.e. shoulder high? chest high? belt high? below the belt? (hint, ask Chris for an observer's perspective).
2. Do you generally make the inside and outside loops the same size in the figure eights and clover or are the insides usually smaller than the outsides?
3. When you check for neutral after hooking up your lines are the attachment points of the up and down lines directly above one another?
4. With the flaps and elevators in neutral during the pre-flight control check is the handle grip vertical or is it tilted forward in the "relaxed, handshake grip" some flyers (incorrectly IMHO) prefer?

Whew!  That'll teach you to ask, huh? 

Ted

 I'll try to answer the questions below (in blue).  and on some I'll need to recheck.

A. Airplane trim:
1. Are the wings level upright and inverted per Chris?  Yes, both ways
2. Do the inside loops on the figure eight maneuvers have the same problem?  sometimes not as bad
3. Same quest re the insides of the four leaf clover. Not as much on the first inside up top,  only on the forth at times.
4. Is the vertical climb in the clover reliably vertical or does it climbs slightly inverted (to your right) and need to be corrected back to vertical?  It locks on tracks vertically
5. In level flight how much of the outboard wheel can you see in front of or behind the inboard wheel in level flight? (Be sure to check first that they are aligned with one another on the ground.) Will have to check
6. Is the airplane easily controlled and "whip-able" in the glide?  Yes
7. How far apart are the leadouts at the wingtip   7/8"   and how far behind the CG is the midpoint of the leadouts when the ship is held balanced on your fingers at the wingtips?  1"
8. Does the prop spin right hand rotation or left hand ("pusher")  Right hand/Tractor (Igors 11x5C)

B. Pilot trim.

1.Where do you hold your "flying" hand in level flight upright and inverted in the vertical axis; i.e. shoulder high? chest high? belt high? below the belt? (hint, ask Chris for an observer's perspective).  Chest high
2. Do you generally make the inside and outside loops the same size in the figure eights   Yes. and clover or are the insides usually smaller than the outsides?   sometimes is manageable.  depends on weather conditions
3. When you check for neutral after hooking up your lines are the attachment points of the up and down lines directly above one another?   I assumed that's at the handle,  Yes.
4. With the flaps and elevators in neutral during the pre-flight control check is the handle grip vertical or is it tilted forward in the "relaxed, handshake grip" some flyers (incorrectly IMHO) prefer?  Vertical,  not relaxed grip.

[Ted Fancher]

 I'll try to answer the questions below (in blue).  and on some I'll need to recheck.

A. Airplane trim:
1. Are the wings level upright and inverted per Chris?  Yes, both ways
2. Do the inside loops on the figure eight maneuvers have the same problem?  sometimes not as bad
3. Same quest re the insides of the four leaf clover. Not as much on the first inside up top,  only on the forth at times.
4. Is the vertical climb in the clover reliably vertical or does it climbs slightly inverted (to your right) and need to be corrected back to vertical?  It locks on tracks vertically
5. In level flight how much of the outboard wheel can you see in front of or behind the inboard wheel in level flight? (Be sure to check first that they are aligned with one another on the ground.) Will have to check
6. Is the airplane easily controlled and "whip-able" in the glide?  Yes
7. How far apart are the leadouts at the wingtip   7/8"   and how far behind the CG is the midpoint of the leadouts when the ship is held balanced on your fingers at the wingtips?  1"
8. Does the prop spin right hand rotation or left hand ("pusher")  Right hand/Tractor (Igors 11x5C)

B. Pilot trim.

1.Where do you hold your "flying" hand in level flight upright and inverted in the vertical axis; i.e. shoulder high? chest high? belt high? below the belt? (hint, ask Chris for an observer's perspective).  Chest high
2. Do you generally make the inside and outside loops the same size in the figure eights   Yes. and clover or are the insides usually smaller than the outsides?   sometimes is manageable.  depends on weather conditions
3. When you check for neutral after hooking up your lines are the attachment points of the up and down lines directly above one another?   I assumed that's at the handle,  Yes.
4. With the flaps and elevators in neutral during the pre-flight control check is the handle grip vertical or is it tilted forward in the "relaxed, handshake grip" some flyers (incorrectly IMHO) prefer?  Vertical,  not relaxed grip.

Hmmm.  Sounds like you're getting pretty darn good coaching from somewhere...in the Pacific Northwest no less!; hard to believe (that's a joke!).

Your answers pretty much matched what I would have expected from someone with excellent observer assistance and pretty much eliminate my concerns about Brett having overlooked alternatives which might have been associated with factors for which I've assigned the terminology "Pilot" trim (i.e. the configuration of and manner of waving the handle which frequently is the cause of misshapen maneuvers). 

The only thing in your reponses I might question is the result of my lack of experience with Tesla Stunt.  The leadout locations you've provided seem very consistent with what I would recommend for an IC ship weighed with no fuel aboard...the general standard for comparison's sake over many years prior to the triple A battery revolution (pardon me, can't help myself!).  Understandably, I've heard and learned from fliers I respect highly that the norm for electric powered ships is to base such things as leadout rake based on the ready to fly condition...very logical since the little electrons you burn aren't very heavy thus the CG (and, thus, the optimal leadout rake) is more or less constant from beginning to end.

The net result of those two conflicting "standards" is that the competitive electrics are generally quoted with more forward CGs and greater leadout rake than comparable IC ships...consistent entirely with their CG/trim status for the entire flight; not requiring the "averaging" necessary when four to eight oz or so gradually disappear forward of the CG in an IC pattern. 

You should take nothing as gospel from me when discussing those few words above.  I would, however, suggest you talk it over with Chris or other e-powered experts to see if you might want to try a little (or possibly more) additional leadout rake.

Thanks for taking the time to respond.

Ted

[Joe Yau]

The only thing in your reponses I might question is the result of my lack of experience with Tesla Stunt.  The leadout locations you've provided seem very consistent with what I would recommend for an IC ship weighed with no fuel aboard...the general standard for comparison's sake over many years prior to the triple A battery revolution (pardon me, can't help myself!).  Understandably, I've heard and learned from fliers I respect highly that the norm for electric powered ships is to base such things as leadout rake based on the ready to fly condition...very logical since the little electrons you burn aren't very heavy thus the CG (and, thus, the optimal leadout rake) is more or less constant from beginning to end.

The net result of those two conflicting "standards" is that the competitive electrics are generally quoted with more forward CGs and greater leadout rake than comparable IC ships...consistent entirely with their CG/trim status for the entire flight; not requiring the "averaging" necessary when four to eight oz or so gradually disappear forward of the CG in an IC pattern. 

You should take nothing as gospel from me when discussing those few words above.  I would, however, suggest you talk it over with Chris or other e-powered experts to see if you might want to try a little (or possibly more) additional leadout rake.

I haven't tried running it ultra nose heavy with LO way back yet.. I guess I could try and see what happens.  Maybe that would help the inside loop issue as well?    But so far what Chris suggested seems to help, and that is to move the up line forward.. which is something I didn't try before as I thought you want to move it after if possible, especially for windy conditions.

[Ken Culbertson]

I have learned a bunch from this thread.  I have a similar problem with the third loop wanting to "e".  Not tail heavy.  Is there a discussion somewhere on flap size and flap/elevator ratio?  I think that I may have too small flaps for good rounds and too much difference in movement.  My flaps are 17% of the chord and the movement is 30 degrees flap to 45 elevator.  I have had a spotter watch the wings in the loops and there is no adverse yaw, wing dropping or evidence tip stall.  It just feels like the elevator is taking over in the 3rd loop.  One thing I have not checked that Ted pointed out is my arm position in the 3d loop.

What should I expect if I went to 20% flaps and/or made the movement equal?

[Ted Fancher]

I have learned a bunch from this thread.  I have a similar problem with the third loop wanting to "e".  Not tail heavy.  Is there a discussion somewhere on flap size and flap/elevator ratio?  I think that I may have too small flaps for good rounds and too much difference in movement.  My flaps are 17% of the chord and the movement is 30 degrees flap to 45 elevator.  I have had a spotter watch the wings in the loops and there is no adverse yaw, wing dropping or evidence tip stall.  It just feels like the elevator is taking over in the 3rd loop.  One thing I have not checked that Ted pointed out is my arm position in the 3d loop.

What should I expect if I went to 20% flaps and/or made the movement equal?

Real quick, Ken as I'm on my way to the gym...

We need more details as to your airplane type (if it's a well known kit/design) or, if not, general "important characteristics; i.e. weight, wing span and area, tail area, etc. to discuss the airplane specific questions you've asked.  A picture would help as well.

In the meantime...

When flying, your handle should be generally in front of you about chest level in level flight and, when flying maneuvers, tracing a smaller version of the maneuver your airplane is flying thus insuring your hand (and any control deflection you are inputting) is in the same relative position "to the airplane" throughout the maneuver.  Do NOT just put in a control input and keep your hand in the same location at a constant angle.  As another responder pointed out, when you give an up control with the airplane at level flight and just keep your handle locked in that position as the airplane climbs it will simultaneously be reducing the angular "input" relationship with you hand and thereby reducing the input to the controls them selves (I.e., if you input a 15 degree angle up control and hold the handle in that same location the airplane would only have to travel 15 degrees above level flight before its location with respect to you input is now zero degrees and its track will now be straight ahead at that angle momentarily and then, as it climbs above 15 degrees your fixed handle position will result in constantly increasing "down" control...the exact opposite of what you want.

That may sound a bit clumsy in the wording but the bottom line remains to follow the airplane through its tricks with smaller versions of the maneuver accomplished primarily by movement with the elbow up to 45 degrees or so and then with shoulder input as the maneuvers get "taller".  Don't give this last a lot of thought but what should logically happen as you do this is that the angular relationship between your hand/handle and your head will remain relatively constant as your head follows what your hand/handle are causing the plane to do.  This is how the best fliers end up with the "back bends" at the top of the vertical eight and the overheads.  If you watch closely the relationship between their hand/handle and their head/eyes will remain pretty consistent.

It would probably be a good idea to "dry fly" this approach a few times if what is described is significantly different from what you do now!

Ted

[Ken Culbertson]

Real quick, Ken as I'm on my way to the gym...

We need more details as to your airplane type (if it's a well known kit/design) or, if not, general "important characteristics; i.e. weight, wing span and area, tail area, etc. to discuss the airplane specific questions you've asked.  A picture would help as well.

In the meantime...

When flying, your handle should be generally in front of you about chest level in level flight and, when flying maneuvers, tracing a smaller version of the maneuver your airplane is flying thus insuring your hand (and any control deflection you are inputting) is in the same relative position "to the airplane" throughout the maneuver.  Do NOT just put in a control input and keep your hand in the same location at a constant angle.  As another responder pointed out, when you give an up control with the airplane at level flight and just keep your handle locked in that position as the airplane climbs it will simultaneously be reducing the angular "input" relationship with you hand and thereby reducing the input to the controls them selves (I.e., if you input a 15 degree angle up control and hold the handle in that same location the airplane would only have to travel 15 degrees above level flight before its location with respect to you input is now zero degrees and its track will now be straight ahead at that angle momentarily and then, as it climbs above 15 degrees your fixed handle position will result in constantly increasing "down" control...the exact opposite of what you want.

That may sound a bit clumsy in the wording but the bottom line remains to follow the airplane through its tricks with smaller versions of the maneuver accomplished primarily by movement with the elbow up to 45 degrees or so and then with shoulder input as the maneuvers get "taller".  Don't give this last a lot of thought but what should logically happen as you do this is that the angular relationship between your hand/handle and your head will remain relatively constant as your head follows what your hand/handle are causing the plane to do.  This is how the best fliers end up with the "back bends" at the top of the vertical eight and the overheads.  If you watch closely the relationship between their hand/handle and their head/eyes will remain pretty consistent.

It would probably be a good idea to "dry fly" this approach a few times if what is described is significantly different from what you do now!

Ted

I can't thank you enough for responding in the way you do.  I do fly pretty much as you describe.  One of your earlier posts on another thread got me thinking so I hid from those who would have me locked up and dry-flew the pattern.   I think I have found the problem.  It is not the plane - it is the pilot.  I learned most my "body English" from flying with Gieseke back in the late 70's.  I trace the pattern with my arm, eyes and just about anything else that will followe.  At 35 it is pretty easy to do that, at 71 it ain't so easy, especially when you are up over 45 and leaning backwards.  I lower myself about a foot when a bottom is called for so that my arm is parallel when I hit 5'.  I am anticipating the exit and not lowering myself on the third loop! Like a good puppy, the plane is simply going where I am pointing!  An otherwise 38 set of loops just became a 35 or worse. You don't fix that by trimming the plane you do it by scolding the pilot!

I have attached a pic of the plane I am using to get back in shape after a 35 year gap.  It is truly a test bed and once I get it flying as well as it can I will build the modernized full fuselage version.  I designed it back in 1963 so there is probably a lot wrong by today's standards.  18% 60" 660sq wing blunt LE high point at 4" (very similar to the Brodak Cardinal airfoil) 17% Flaps 2 to 3 Flap Elevator Ratio, 17" tail movement 9 1/2 nose.  CG at 2 3/4", 3-1/2 Morris controls, Leadouts center 1" behind C/G with 3/4" spacing  52oz dry, OS46LA 11-5 prop thinking of trying a 12-4.

Right now it flies better than I do but that will change if I can figure out how to do an overhead 8 without having to change foot position while looking straight up.  God did plan for the Human Body to have to do this at 71!  Only bad habit is some slight roll (both directions like it has too much tip weight) in corners.  I see it from the inside and it bother's me but those watching don't see it and comment on how smooth it turns for a profile.  I am adding a tab to the outboard flap to see if that makes a difference.

Ken



   

[Ted Fancher]

I can't thank you enough for responding in the way you do.  I do fly pretty much as you describe.  One of your earlier posts on another thread got me thinking so I hid from those who would have me locked up and dry-flew the pattern.   I think I have found the problem.  It is not the plane - it is the pilot.  I learned most my "body English" from flying with Gieseke back in the late 70's.  I trace the pattern with my arm, eyes and just about anything else that will followe.  At 35 it is pretty easy to do that, at 71 it ain't so easy, especially when you are up over 45 and leaning backwards.  I lower myself about a foot when a bottom is called for so that my arm is parallel when I hit 5'.  I am anticipating the exit and not lowering myself on the third loop! Like a good puppy, the plane is simply going where I am pointing!  An otherwise 38 set of loops just became a 35 or worse. You don't fix that by trimming the plane you do it by scolding the pilot!

I have attached a pic of the plane I am using to get back in shape after a 35 year gap.  It is truly a test bed and once I get it flying as well as it can I will build the modernized full fuselage version.  I designed it back in 1963 so there is probably a lot wrong by today's standards.  18% 60" 660sq wing blunt LE high point at 4" (very similar to the Brodak Cardinal airfoil) 17% Flaps 2 to 3 Flap Elevator Ratio, 17" tail movement 9 1/2 nose.  CG at 2 3/4", 3-1/2 Morris controls, Leadouts center 1" behind C/G with 3/4" spacing  52oz dry, OS46LA 11-5 prop thinking of trying a 12-4.

Right now it flies better than I do but that will change if I can figure out how to do an overhead 8 without having to change foot position while looking straight up.  God did plan for the Human Body to have to do this at 71!  Only bad habit is some slight roll (both directions like it has too much tip weight) in corners.  I see it from the inside and it bother's me but those watching don't see it and comment on how smooth it turns for a profile.  I am adding a tab to the outboard flap to see if that makes a difference.

Ken 

Hi Ken, thanks for the extensive response.

No. 1, I love your plane!  It's a very sound looking design. 

In a lot of ways it looks like I stole some of it when I designed the Imitation.  I particularly like the narrow chord flaps and think, given the very light wing loading at 52oz, the 2/3 flap/elevator ratio is probably a very good decision.  Plenty of lift available for the weight and the narrower chord and reduced deflection will both provide a crisper turn and do so with modest effort...both very good things for repetitive precision maneuvers.  Just eyeballing it the tail looks to be larger than was common back in the early '70s.  If the airplane flies and maneuvers stable-y with the CG location you've mentioned I would guess the area is in the vicinity of 20% or more of the wing??

From their appearance the hinges appear to be "pin" style rather than the flat, hinged nylon ones more commonly used.  Noticing them did make me want to ask if you've sealed the hinge lines.  Yes?  No?  If not and the gaps on flaps different--greater on the outboard wing, for instance, that could also be a source of the outboard roll in both insides and outsides.  As I'm sure you've read from me before, I'm a big believer in sealed hingelines ever since I got gob-smacked at lunch be Denny Adamisin decades ago when he casually mentioned he always did so!  Of course they should be sealed. 

At any rate, consider doing so if you haven't.

Can't tell if the there is any asymmetry in the wing but it sorta looks like equal span.  The amount of tip weight required for proper roll trim is influenced considerably by any asymmetry, as you know.  I would trust myself re the roll in maneuvers you mentioned and remove tip weight until there is none from your perspective or, as you've suggested and the weight isn't adjustable, adding a tab to the outboard flap to trim out the roll.

Gotta love having a legend like Bob for a flying partner.  If one is going to fudge off somebody might as well be a CLPA legend who also was a World Champion!  One thing you might want to think about, however, is that Bob, in his Fox .35 Championship years was flying a very light ship very slowly and, as was common in that era, utilized subtle but real pilot influence on the airplane through leading, whipping and adding, subtracting energy when appropriate.  Pilot skills and talents that are much less a part of flying stunt with today's comparative tractor pullers on strings.  You might want to consider less body input such as squatting on pullouts, etc. which are pretty much unnecessary and add non-essential movements on the pilot end of the handle.  Less is more nowadays.  Smaller, controlled inputs using as little motion beyond the forearm, wrist and fingers can easily provide the inputs required and, being smaller, are much more repeatable and less apt to make big mistakes than attempting to make the rapid fire inputs necessary for much of the pattern using larger motions.

I'm running off at the mouth and saying very little.  Don't suppose there's any chance you'll be in the San Francisco/Sacramento area the end of June is there?  Uncle Jimby Aron is putting on the annual "Chumley (his late beloved dog) Memorial Stunt Clinic" on the 23/24.  It's a fun weekend at a fine dedicated flying site near Woodland, Davis. Brett Buck, David Fitzgerald and I help Jim assist people in trimming both their airplanes and their patterns.

Unlikely I suppose but I'd love to see that red, white and blue thing of yours in the air.

Ted

[Ken Culbertson]

Hi Ken, thanks for the extensive response.

No. 1, I love your plane!  It's a very sound looking design. 

In a lot of ways it looks like I stole some of it when I designed the Imitation.  I particularly like the narrow chord flaps and think, given the very light wing loading at 52oz, the 2/3 flap/elevator ratio is probably a very good decision.  Plenty of lift available for the weight and the narrower chord and reduced deflection will both provide a crisper turn and do so with modest effort...both very good things for repetitive precision maneuvers.  Just eyeballing it the tail looks to be larger than was common back in the early '70s.  If the airplane flies and maneuvers stable-y with the CG location you've mentioned I would guess the area is in the vicinity of 20% or more of the wing??

From their appearance the hinges appear to be "pin" style rather than the flat, hinged nylon ones more commonly used.  Noticing them did make me want to ask if you've sealed the hinge lines.  Yes?  No?  If not and the gaps on flaps different--greater on the outboard wing, for instance, that could also be a source of the outboard roll in both insides and outsides.  As I'm sure you've read from me before, I'm a big believer in sealed hingelines ever since I got gob-smacked at lunch be Denny Adamisin decades ago when he casually mentioned he always did so!  Of course they should be sealed. 

At any rate, consider doing so if you haven't.

Can't tell if the there is any asymmetry in the wing but it sorta looks like equal span.  The amount of tip weight required for proper roll trim is influenced considerably by any asymmetry, as you know.  I would trust myself re the roll in maneuvers you mentioned and remove tip weight until there is none from your perspective or, as you've suggested and the weight isn't adjustable, adding a tab to the outboard flap to trim out the roll.

Gotta love having a legend like Bob for a flying partner.  If one is going to fudge off somebody might as well be a CLPA legend who also was a World Champion!  One thing you might want to think about, however, is that Bob, in his Fox .35 Championship years was flying a very light ship very slowly and, as was common in that era, utilized subtle but real pilot influence on the airplane through leading, whipping and adding, subtracting energy when appropriate.  Pilot skills and talents that are much less a part of flying stunt with today's comparative tractor pullers on strings.  You might want to consider less body input such as squatting on pullouts, etc. which are pretty much unnecessary and add non-essential movements on the pilot end of the handle.  Less is more nowadays.  Smaller, controlled inputs using as little motion beyond the forearm, wrist and fingers can easily provide the inputs required and, being smaller, are much more repeatable and less apt to make big mistakes than attempting to make the rapid fire inputs necessary for much of the pattern using larger motions.

I'm running off at the mouth and saying very little.  Don't suppose there's any chance you'll be in the San Francisco/Sacramento area the end of June is there?  Uncle Jimby Aron is putting on the annual "Chumley (his late beloved dog) Memorial Stunt Clinic" on the 23/24.  It's a fun weekend at a fine dedicated flying site near Woodland, Davis. Brett Buck, David Fitzgerald and I help Jim assist people in trimming both their airplanes and their patterns.

Unlikely I suppose but I'd love to see that red, white and blue thing of yours in the air.

Ted

Thanks for the kind words.  I had no idea what I was doing when I first designed it.  At 16 you just do what looks cool and you really don't know why it works, only that it does.
I think I stole a lot of it from the Ballerina and Olympic and from my uncle who flew B-25's in WWII.  It does have big tail feathers and a really long rear end for the 60's.  Needless to say at 40oz with a Fox 35 it would do square corners that were square, but it really was controlled free flight!  Remarkably it flew well in wind.

No one is too old to change and I think I am going to take your advice and start letting the plane do the work.  There aren't many of us left here in Dallas.  It was like Mecca in the late 70's with Gieseke, Rabe, Pilgrim, Ruthefford all likely to show up for even the smallest fun fly.  I am still blessed to be able to fly on occasion with Doug Moon.  Watching him fly Bob's Bear the way he does after having judged him as a kid, when a good day was one where he took the plane home, really gives me hope. 

I knew things had changed the first time I took that OS46 overhead and it had more line tension that I ever remember having in level flight before.  So it looks like I have to learn to fly all over again - sort of.

Ken

[Ken Culbertson]

Hi Ken, thanks for the extensive response.

Ted:

Quick follow up.  I took your advice this morning and tried my best to kill the Body English.    Dramatic difference but it is going to take a few more flights to get used to it.  The only thing I find difficult to give up is planting my feet apart.  I think I will keep that, less likely to fall down.  I use it to center a maneuver and define intersections.   I tried the "Brett Bart" stance and my intersections ended up in different zip codes.  I can see I was flying like it was a the 60's where you had to bargain, plead, threaten, burp and in some cases chase it down...and that was on a good day.  But there is more...I was accused and found guilty of putting my inside and outside loops about an 1/8th circle past down wind.  Guess you don't do that anymore either.  All and all, between you and Doug I put 50 points back on my pattern today.  Keep this up and I will be back to placing last in Expert before you know it!

Thanks for the advice  - Ken

FYI - you have an amazing eye for design - the tail is exactly 20%.

[Steve Helmick]

While I'm not certain that this applies, when I was first flying the ex-Haverly "Kiss!" (Fancherized Twister), it became obvious first flight that it was tail heavy, because it would only glide about 1/4 lap after engine shutdown. So I put an OS .46LA muffler on the Magnum XLS .36, replacing a tongue muffler, IIRC. Much better! Later, when i tried moving the LO's forward, things got worse, so apparently Mike had them too far forward for his rearward CG location. I put them back where Mike had them.

With it then at 47 oz., I started looking at the control ratios and realized that the flaps were not moving 1:1 with the elevators, but it was a simple fix to move the flap pushrod to get it to 1:1. When I started flying it after this change, it did severe "e" loops. I can't recall getting past the loops, because it really freaked me out.

Since, i've wondered if too much flap area would do the same, but I don't know. Seems to me like it would. It also could be that larger elevators might be an alternative to narrowing the flaps, so if you are reluctant to slice 1/2" off the TE of the flaps, then maybe you could tape 1/2"+ onto the elevators and see what happens?

I ended up going to 2.5" line spacing and gradually widening the spacing out to about 3.25" over a month or so, re-training the pilot. Not what I wanted, but acceptable. It's a common problem from 3" BC/short flap horn and resulting too fast controls. Wider handle spacing  **with suitably slow controls**  improves control input accuracy.  Steve

[Ken Culbertson]

While I'm not certain that this applies, when I was first flying the ex-Haverly "Kiss!" (Fancherized Twister), it became obvious first flight that it was tail heavy, because it would only glide about 1/4 lap after engine shutdown. So I put an OS .46LA muffler on the Magnum XLS .36, replacing a tongue muffler, IIRC. Much better! Later, when i tried moving the LO's forward, things got worse, so apparently Mike had them too far forward for his rearward CG location. I put them back where Mike had them.

With it then at 47 oz., I started looking at the control ratios and realized that the flaps were not moving 1:1 with the elevators, but it was a simple fix to move the flap pushrod to get it to 1:1. When I started flying it after this change, it did severe "e" loops. I can't recall getting past the loops, because it really freaked me out.

Since, i've wondered if too much flap area would do the same, but I don't know. Seems to me like it would. It also could be that larger elevators might be an alternative to narrowing the flaps, so if you are reluctant to slice 1/2" off the TE of the flaps, then maybe you could tape 1/2"+ onto the elevators and see what happens?

I ended up going to 2.5" line spacing and gradually widening the spacing out to about 3.25" over a month or so, re-training the pilot. Not what I wanted, but acceptable. It's a common problem from 3" BC/short flap horn and resulting too fast controls. Wider handle spacing  **with suitably slow controls**  improves control input accuracy.  Steve

I know that much of this is style and some, or maybe many, will disagree but I have never found large flaps or flap movement attractive.  I like a plane that rotates around the CG or as close as you can get.  Large flaps and/or large deflection tend to make the plane feel like it is rotating around the tail.  Too little and it feels like you are rotating around the nose.  I use flap chords that are about 1/2 shorter than most and an elevator chord that is on the large side of average for today's ships.  Where I differ from most is that I use a 2-3 Flap Elevator ratio and a full airfoil on the stab/elevator.  Nothing new here, it is just the combination that works for me.   

Ken

[Ted Fancher]

Ted:
"snip"

The only thing I find difficult to give up is planting my feet apart.  I think I will keep that, less likely to fall down.  I use it to center a maneuver and define intersections.   I tried the "Brett Bart" stance and my intersections ended up in different zip codes.

"snip"

  I can see I was flying like it was a the 60's where you had to bargain, plead, threaten, burp and in some cases chase it down...and that was on a good day. 

"snip"

But there is more...I was accused and found guilty of putting my inside and outside loops about an 1/8th circle past down wind.  Guess you don't do that anymore either.  All and all, between you and Doug I put 50 points back on my pattern today.  Keep this up and I will be back to placing last in Expert before you know it!

"snip"

FYI - you have an amazing eye for design - the tail is exactly 20%.

You're very welcome.  Glad some of this has been helpful.  Just have a few thoughts on the separated comments above.

RE spread feet while maneuvering.  Do NOT stop doing so.  Part of my preparation for each maneuver is feeling the air movement during the intervening laps and determining where I'm going to do the next maneuver. Half way through the second lap I will have made up my mind and start preparing for the maneuver.  Appx 1/4 to 1/8 of the circle prior to starting I will make a distinct step with my left foot to the point I anticipate will be the proper place halfway past the middle of the maneuver, follow that with a plant of my right foot and then wait for the airplane to enter an arc of the circle on which my stance is centered.  My feet then stay planted with the expectation that 1/2 of the maneuver will be on each side of directly in front of my body.  Doing so provides a "frame" within which to contain the maneuver as well as recognizing that directly in front of that stance should be the middle of the trick.  Again, the "tractor pull" nature of modern power trains is what makes this more or less foundation a valuable aid as we seldom have to engage in assisting the the airplane.

Whipping, etc.  Glad you've considered the difference of "then" versus "now" with respect to how much help we need to assist the mechanical half of our plane/pilot team.  Using our body parts to frame maneuvers is a big asset so we shouldn't throw it away to look like Dancing With the Stars contestants.  Brett Buck is the poster boy for this technique looking more than a bit like the Statue of Liberty with a nimble right arm/hand while driving his Infinite through near picture perfect tricks.

Biased into the wind loops.  I'll have to part company just a bit with Doug (who I expect is your local source of inputl).  I still feel it is of some value in modest to greater wind but, again, the distortion of the loops due to flying dead downwind is greatly mitigated with modern powertrains and taking proper advantage of the better pitch trimming capabilities provided by the larger/longer tails and further aft CGs they allow combined with the improved speed control of our modern motivators.  Much less tendency to wind up and open up consecutive loops.  In my case still doing so might well be the last remnant of calcified technique from my hay days!

Your tail end...um, that is...your airplane's tail end.  I was thinking about that today while watching Shareen shop.  Yeah, I was guessing it looked around 20% or so and had at first thought the CG location you quoted sounded a little on the overly aft side (24% or so IIRC).  Then I remembered the twin rudders on each tail tip and rethought my concerns.  As I recall it was your Texas Moon Brothers (with, perhaps, a jump start from Gene Schaffer) that started putting twin vertical fins back there and planning/discovering they made the tail more effective...most likely as a result of reducing vortexes off each tip.  Assuming your measurements were accurate (don't doubt it) the tail's size and CG location tend to verify the speculation.

Bottom line, I'm very pleased you've had positive results from your recent efforts.  I look forward to one day getting a chance to meet.

Ted

[Joe Yau]

While I'm not certain that this applies, when I was first flying the ex-Haverly "Kiss!" (Fancherized Twister), it became obvious first flight that it was tail heavy, because it would only glide about 1/4 lap after engine shutdown. So I put an OS .46LA muffler on the Magnum XLS .36, replacing a tongue muffler, IIRC. Much better! Later, when i tried moving the LO's forward, things got worse, so apparently Mike had them too far forward for his rearward CG location. I put them back where Mike had them.

With it then at 47 oz., I started looking at the control ratios and realized that the flaps were not moving 1:1 with the elevators, but it was a simple fix to move the flap pushrod to get it to 1:1. When I started flying it after this change, it did severe "e" loops. I can't recall getting past the loops, because it really freaked me out.

Since, i've wondered if too much flap area would do the same, but I don't know. Seems to me like it would. It also could be that larger elevators might be an alternative to narrowing the flaps, so if you are reluctant to slice 1/2" off the TE of the flaps, then maybe you could tape 1/2"+ onto the elevators and see what happens?

I ended up going to 2.5" line spacing and gradually widening the spacing out to about 3.25" over a month or so, re-training the pilot. Not what I wanted, but acceptable. It's a common problem from 3" BC/short flap horn and resulting too fast controls. Wider handle spacing  **with suitably slow controls**  improves control input accuracy.  Steve

Hi Steve,  I think that's it!  now I remember how I fixed the "e" issue way back..   The culprit was too much flaps..  which made it feel nose heavy, so I added tail weight.. then it flew better.  till I did a simple inside loop on a windy day.  That's when the inside loop went like an "e" . I tried biasing the handle etc to compensate it .. even though it was a little more under control, but it caused other issues.   The "e" issue didn't go away till I decreased the flaps deflections.  I set it close to a 2/3 ratio on the adjustment.. On the first test flight,  the plane feels way too tail heavy.  I ended up removing .5 oz off the tail.  then it flew better then ever. and I didn't notice much of the "e"  tendency on the inside loop.   I'll have to try that on the Legacy if the "e" tendency is not 100% all gone. It does make sense, as the Legacy is fairly light (61.5oz with batt)  and the flaps/elev ratio is near 1:1.  with CG .5"ahead vs IC 

[Ken Culbertson]

Hi Steve,  I think that's it!  now I remember how I fixed the "e" issue way back..   The culprit was too much flaps..  which made it feel nose heavy, so I added tail weight.. then it flew better.  till I did a simple inside loop on a windy day.  That's when the inside loop went like an "e" . I tried biasing the handle etc to compensate it .. even though it was a little more under control, but it caused other issues.   The "e" issue didn't go away till I decreased the flaps deflections.  I set it close to a 2/3 ratio on the adjustment.. On the first test flight,  the plane feels way too tail heavy.  I ended up removing .5 oz off the tail.  then it flew better then ever. and I didn't notice much of the "e"  tendency on the inside loop.   I'll have to try that on the Legacy if the "e" tendency is not 100% all gone. It does make sense, as the Legacy is fairly light (61.5oz with batt)  and the flaps/elev ratio is near 1:1.  with CG .5"ahead vs IC 

You will probably also notice that it corners easier, not necessarily better, just easier.  I even changed my ARF Nobler to 2-3 and it flies,  or I fly it, much better.

Ken

Ken

[Steve Helmick]

Hi Steve,  I think that's it!  now I remember how I fixed the "e" issue way back..   The culprit was too much flaps..  which made it feel nose heavy, so I added tail weight.. then it flew better.  till I did a simple inside loop on a windy day.  That's when the inside loop went like an "e" . I tried biasing the handle etc to compensate it .. even though it was a little more under control, but it caused other issues.   The "e" issue didn't go away till I decreased the flaps deflections.  I set it close to a 2/3 ratio on the adjustment.. On the first test flight,  the plane feels way too tail heavy.  I ended up removing .5 oz off the tail.  then it flew better then ever. and I didn't notice much of the "e"  tendency on the inside loop.   I'll have to try that on the Legacy if the "e" tendency is not 100% all gone. It does make sense, as the Legacy is fairly light (61.5oz with batt)  and the flaps/elev ratio is near 1:1.  with CG .5"ahead vs IC 

Joe, I'd suggest checking posts about PW and Howard's CG specs for E-power...seems to me like it was much more than .5" ahead of IC location. Actually, I think 7/8" was more like it. I'm curious about Paul's extra aft LO's, why that works, or if anybody else has come to use that trim. Maybe Chris or Arkady? I don't think Alan would, since he flies clockwise. GL & GF!    Steve

[Steve Helmick]

You will probably also notice that it corners easier, not necessarily better, just easier.  I even changed my ARF Nobler to 2-3 and it flies,  or I fly it, much better.

Ken

Reduced control loads, I'd expect. Howard may come along and use real engine ear terminology. Flaps are a majority of the control loads we feel in the handle. Probably real important in the wind, or if you are trying to fly slow lap times, since line tension powers up the control system. Just a retired machinist's gut instinct, of course. How much does your NoblARF weigh, and what power?  Steve

[Joe Yau]

You will probably also notice that it corners easier, not necessarily better, just easier.  I even changed my ARF Nobler to 2-3 and it flies,  or I fly it, much better.

Ken

Ken

Yes, the corner were tighter, it rotates around the CG during the turn. and could be flown tight or soft not like before just turns soft.  also the rounds are more predictable. 

[Joe Yau]

Joe, I'd suggest checking posts about PW and Howard's CG specs for E-power...seems to me like it was much more than .5" ahead of IC location. Actually, I think 7/8" was more like it. I'm curious about Paul's extra aft LO's, why that works, or if anybody else has come to use that trim. Maybe Chris or Arkady? I don't think Alan would, since he flies clockwise. GL & GF!    Steve

I've seen Paul's post on it, but he never did elaborate on it.   Chris, Alan and Ark use that trim. I have asked Chris what he notice by doing that..  he just said Paul saids it flys better.    I have briefly tried that trim on the Saturn that was converted from IC, and didn't like it. maybe I don't know what to expect.. I would think it should have more line tension?  If I run 70' lines.  maybe my lines are not long enough for the extreme after LO position?   with 1" ahead CG.. it puts the flaps in play more then Elev.  I would need to reduce the flap deflections.. wouldn't I?   or it is strictly a wind trim.. to minimize speed ups?   I have no idea..   

[Ted Fancher]

Joe, Steve and Ken,

The primary aerodynamic phenomenon you're experiencing is the "adverse pitching moment" created by cambering (or further cambering) an airfoil when the flaps are deflected.  In addition to increasing the control loads the pilot must overcome, deflecting flaps while maneuvering attempts to pitch the airfoil and, therefore the vehicle to which it is attached in the opposite direction from the pitch change desired.  This is why you've experienced the more rapid pitch change when reducing the flap movement (and/or area).  The effect is exacerbated the further forward the CG is from the Center of lift which, again, impacted your experiences with reducing the flap movement then finding the need to readjust the CG.

This is the reason I had positive comments about the narrow chord of the flaps on Ken's ship a number of posts back.  I firmly believe flaps should be no broader in chord than necessary to produce only a modest excess in lift to that required to perform the pattern in a championship fashion!  Also a very good reason, in my estimation, to have the CG no further forward than necessary to be stable in both level flight and when maneuvering accurately.

You can experience the phenomenon very dramatically in action by suffering the failure of the pushrod between the flaps and elevators in level flight and then trying to save the ship by giving up control thus deflecting only the flaps.  Do the test on an old ship if you are going to do it.

I don't know...but Howard and/or Paul probably do...but I'm guessing that if the CG were well aft of the center of lift of the mainplane the opposite result--a shallow climb--might result.  I don't believe this would be the case for any remotely conventional stunter, however.

If you've copies of the old Imitation article you can read about the experiments I performed with flaps (narrow chord per my preference) which could be operated at three different lengths depending on how many of the outer two segments of both sides were operative.  The results pretty much mirrored your discussion with the only exception being the CG was never so far aft that good patterns couldn't be flown.  The change in the rate of pitch change per unit of input was dramatic even though the adjustable sections were not a large percentage of the flap span.

Ted

[Target]

So, I understand that the pitching moment increases with increased camber, and that the tail has to compensate and then some for the added pitching from the cambered wing, to effect the desired pitch response.

Why does a combat wing with the elevator hinged at the TE of the wing then work in the standard directions??


Thanks and good morning from cloudy SoCal on this day of remembrance of our fallen service men and women.
And thanks so much to all those that have served and those who are currently serving, for your daily sacrifices.

R,
Target

[Joe Yau]

Joe, Steve and Ken,

The primary aerodynamic phenomenon you're experiencing is the "adverse pitching moment" created by cambering (or further cambering) an airfoil when the flaps are deflected.  In addition to increasing the control loads the pilot must overcome, deflecting flaps while maneuvering attempts to pitch the airfoil and, therefore the vehicle to which it is attached in the opposite direction from the pitch change desired.  This is why you've experienced the more rapid pitch change when reducing the flap movement (and/or area).  The effect is exacerbated the further forward the CG is from the Center of lift which, again, impacted your experiences with reducing the flap movement then finding the need to readjust the CG.

This is the reason I had positive comments about the narrow chord of the flaps on Ken's ship a number of posts back.  I firmly believe flaps should be no broader in chord than necessary to produce only a modest excess in lift to that required to perform the pattern in a championship fashion!  Also a very good reason, in my estimation, to have the CG no further forward than necessary to be stable in both level flight and when maneuvering accurately.

You can experience the phenomenon very dramatically in action by suffering the failure of the pushrod between the flaps and elevators in level flight and then trying to save the ship by giving up control thus deflecting only the flaps.  Do the test on an old ship if you are going to do it.

I don't know...but Howard and/or Paul probably do...but I'm guessing that if the CG were well aft of the center of lift of the mainplane the opposite result--a shallow climb--might result.  I don't believe this would be the case for any remotely conventional stunter, however.

If you've copies of the old Imitation article you can read about the experiments I performed with flaps (narrow chord per my preference) which could be operated at three different lengths depending on how many of the outer two segments of both sides were operative.  The results pretty much mirrored your discussion with the only exception being the CG was never so far aft that good patterns couldn't be flown.  The change in the rate of pitch change per unit of input was dramatic even though the adjustable sections were not a large percentage of the flap span.

Ted

Hi Ted,  Thanks for the reassuring..    It is one of the reason I fly the Primary Force (flapless/ In-line) every now & then..  basically to check some of what the PF does right against the trim on the PA (flapped) ship.

[Ted Fancher]

So, I understand that the pitching moment increases with increased camber, and that the tail has to compensate and then some for the added pitching from the cambered wing, to effect the desired pitch response.

Why does a combat wing with the elevator hinged at the TE of the wing then work in the standard directions??


Thanks and good morning from cloudy SoCal on this day of remembrance of our fallen service men and women.
And thanks so much to all those that have served and those who are currently serving, for your daily sacrifices.

R,
Target

An apparently obvious question, Target, for which, I expect you'll be a little embarrassed to have asked. 

It's because when you give up"elevator" to what in reality is a "flap" attached to the back of the wing it creates an "adverse pitching moment" which now, Oh my gosh!, is exactly what you want in order to make your combat ship pitch up to escape the aggressor (or vice versa)!  The popularity of doing so, however, was very short lived.

The inefficiency of using adverse pitching moment to pitch a combat ship is exactly why the whole period of doing so by combat fliers was, early on, eliminated when guys like Riley Wooten,etc. back in the late '50s early '60s started putting booms on the trailing edges of their wings to which they attached for real tails, albeit generally flying stabilizers (no fixed stab, only the flipper in most cases).

The inefficiency of using a "flap" for aggressive pitching on a combat ship was that, by definition, the aircraft to which it was attached was allowed to pitch in the direction that "reduced" the lift which the "wing" was capable of producing  thus restricting the performance of which it would be capable with the later "boom"d tail variants (similar to a "spoiler/speed-brake which you might recall seeing popping up periodically on the top of most jetliner wings periodically during flight and always during the landing rollout).  Sort of like trying to do an outside loops with a Piper Cub with its essentially flat bottomed Clark Y style airfoil!

Another well known example of a clever innovation of similar ooops aerodynamic value was in the world of Stunt...now CLPA.  The very bright and popular early star innovator in control line, Wild Bill Netzeband designed and published a very clever (he thought) and unique stunt ship called the Fierce Arrow which was an enlarged and "prittied up" version of his Half Fast (thanx, Steve Helmick) combat design (you can google for pix using Bill Netzeband model airplane designs).  This ship doubled down on the "trailing edge flipper" concept by utilizing a nearly full span flap as the sole "pitch" devise.  The design had an early spate of popularity due to its unique "Star Wars" sort of personna.  When its performance failed to prove competitive in any real sense it quickly became a popular blip in the progress of stunt design.  About the only place one was apt to show up was at VSC.  Versions there never failed to draw attention...but no trophies!

Sorry for running off at the mouth.

Ted

p.s.  a heartfelt ditto to your well stated paean to our armed forces.

[Steve Helmick]

Ted wrote:……..."prittied up" version of his Fierce Arrow combat design (


The Wild Bill combat design was called the "Half Fast". I never had a .35 sized one, but did have a 1/2A version, made from a Midwest kit when I was about 13. I had the same question as Mr. Target, and my devilish older brothers both assured me that "down elevator" would indeed make the model climb. You know how you just get "that feeling" when you think somebody is blowing smoke up your butt? I took it out in the yard and swung it around on 10' lines to find out they were full of chit and being asshats, whcih was pretty common.

In retrospect, line tension is a problem with both the FA and HF. Huge elevator chord, bad news. I recall well seing Don McClave's HF doing the RWO with quite slack lines. I'm still tempted by Mikey's Models "Delta Force". https://stunthanger.com/smf/mikey's-models/delta-force-plans/ It looks very cool, and would be a great sport flier with a .46 LA or ST G.51.     Steve

[Ted Fancher]

Ted wrote:……..."prittied up" version of his Fierce Arrow combat design (


The Wild Bill combat design was called the "Half Fast". I never had a .35 sized one, but did have a 1/2A version, made from a Midwest kit when I was about 13. I had the same question as Mr. Target, and my devilish older brothers both assured me that "down elevator" would indeed make the model climb. You know how you just get "that feeling" when you think somebody is blowing smoke up your butt? I took it out in the yard and swung it around on 10' lines to find out they were full of chit and being asshats, whcih was pretty common.

In retrospect, line tension is a problem with both the FA and HF. Huge elevator chord, bad news. I recall well seing Don McClave's HF doing the RWO with quite slack lines. I'm still tempted by Mikey's Models "Delta Force". https://stunthanger.com/smf/mikey's-models/delta-force-plans/ It looks very cool, and would be a great sport flier with a .46 LA or ST G.51.     Steve

Oooops.  Good catch, Steve.  You'da thunk if a guy has the time to blather as much as I do he'd find time to proof read, wouldn't you.

I never built or flew a Fierce Arrow but watched a number of them including one Bob Emmett built a lifetime ago and before I could/would have questioned Wild Bill's expertise.  The later one's at VSC for the most part displayed an unpleasant  willingness to try to stall in the bottom diving corners of things like the triangles and hourglasses.  I'm thinking that the almost full span flap/elevator/flipper left almost none of the span capable of maintaining a positive angle of attack and thus the failure to complete the corners smoothly.  Don't recall any of them actually crashing but do recall the builder/fliers saying the would purposely back off those corners to prevent such a thing.

Ted

p.s.  thanks for the link to the Delta Force.  I was totally unaware of the design.

[Target]

An apparently obvious question, Target, for which, I expect you'll be a little embarrassed to have asked. 

It's because when you give up"elevator" to what in reality is a "flap" attached to the back of the wing it creates an "adverse pitching moment" which now, Oh my gosh!, is exactly what you want in order to make your combat ship pitch up to escape the aggressor (or vice versa)!  The popularity of doing so, however, was very short lived.

Ted

p.s.  a heartfelt ditto to your well stated paean to our armed forces.

Ted-

Yes, Duh! And thank you for the explanation of the painfully obvious.

I have my GF over for the weekend, and I swear that my aero IQ goes down to half what it is normally when she is here. 


V/r,

Target

[Ted Fancher]

Ted-

Yes, Duh! And thank you for the explanation of the painfully obvious.

I have my GF over for the weekend, and I swear that my aero IQ goes down to half what it is normally when she is here. 


V/r,

Well....As long as there's a logical explanation!  You're welcome.

Target

[Target]

That's my story and I'm sticking to it.
She's at work tomorrow, but I'm on a rare day off, so I hope to recover some brain cells working in the shop on some planes.

I'm really bummed I can't make the annual Davis stunt tutorial that you and some other notables will be at in June; I have a longer work mission that I cannot financially miss out on.
Hopefully next year.

Happy Memorial Day.

R,
Target

[Ted Fancher]

That's my story and I'm sticking to it.
She's at work tomorrow, but I'm on a rare day off, so I hope to recover some brain cells working in the shop on some planes.

I'm really bummed I can't make the annual Davis stunt tutorial that you and some other notables will be at in June; I have a longer work mission that I cannot financially miss out on.
Hopefully next year.

Happy Memorial Day.

R,
Target

There are priorities in life, Target, and if we're wise we order them properly.  Hopefully you'll get a chance next year.

Just curious.  Where abouts in SoCal do you live and do you fly with some of the crowd down there on a regular basis?

Ted

[Target]

I fly with the codgers at Whittier Narrows on Fridays, so I am flying with the Knights there.

I'm a retread from way back (twice, as a teen and as a younger step-dad with .049's) but got into stunt and  U/C to hang out with one of my glider flying buddies, Don Repp.
I blame Don for getting me started in U/C. We made a trip to Slovakia to fly on the USA F3F team, it was a blast.
I'm having fun, and I assume that if the FAA cracks down on "Drones", that U/C will most likely be (I hope) bypassed by their regulations. More likely than the sailplane stuff I love to fly.

R,
Target

[Ken Culbertson]

I fly with the codgers at Whittier Narrows on Fridays, so I am flying with the Knights there.

I'm a retread from way back (twice, as a teen and as a younger step-dad with .049's) but got into stunt and  U/C to hang out with one of my glider flying buddies, Don Repp.
I blame Don for getting me started in U/C. We made a trip to Slovakia to fly on the USA F3F team, it was a blast.
I'm having fun, and I assume that if the FAA cracks down on "Drones", that U/C will most likely be (I hope) bypassed by their regulations. More likely than the sailplane stuff I love to fly.

R,
Target

What is it about Stunt and Soaring?  Seems like there are a lot of us.  Not much slope in Texas but we do have thermals, man do we have thermals.  Perfect combination.  Too windy for Stunt is about windy enough for sailplanes.

Ken

[Target]

Yes, they seem to be opposites, but both are so much fun.
Truth be told, I'm more drawn to themal soaring than slope, Ken.

I've taken note of the flap/elevator ratio reduction as a tuning aid. To keep this thread steered on topic. That and chord reduction in flaps as needed.
The great amount of flap movement has always amazed me in stunt planes. I use probably about 3-4 degrees in my sailplanes. It's very effective. Too much is bad, too draggy. But there's no prop pulling the plane though manuevers
Ken i also love DLG flying. I have 3 of them.

[Ted Fancher]

"Snip"

I've taken note of the flap/elevator ratio reduction as a tuning aid. To keep this thread steered on topic. That and chord reduction in flaps as needed.
The great amount of flap movement has always amazed me in stunt planes. I use probably about 3-4 degrees in my sailplanes. It's very effective. Too much is bad, too draggy. But there's no prop pulling the plane though maneuvers

"snip"

Yes, adjusting flap/elev ratios is a valid trim mechanism although, if flap chord is kept within a reasonable range...say 12 to 20% of chord or so...one to one is generally not a bad place to start.  With reference to sailplanes it's important to remember two things.  First, the wing loading of a stunt ship is generally somewhat higher than that of the sailplane and the aspect ratio a "lot" less than the sailplane...thus the increase in lift for a given rate of angle of attack change is much greater for the sailplane.  Second the increased "G" loading demanded of a stunt ship in maneuvering requires rapid and significant increases in lift from it's much less efficient lower aspect ratio wing.  Thus the demands for more energetic devices to supply that lift!

There is another aspect of flap deflection that is seldom discussed but very valuable especially with respect to modern stunt ship design, i.e. large/long tail areas and moment arms.  Strangely enough, that advantage is the adverse pitching moment the flaps produce!  Here's why.

Almost all of us started out in "big" stunt with un-flapped ships like Ringmasters, Yaks, Mustangs and Goldberg stunters.  All of these used CG locations well ahead of what we aim for now with our big/long tailed flapped ships.  CGs at or near 25% on those airplanes would have been thought of as way too tail heavy and the response to control inputs way too aggressive and, if the tail was not large enough, potentially unflyable.  Thus the usual CG location was well ahead of the nominal center of lift of the symmetrical airfoiled wing (~25% MAC).  This distance between the CG and CL produced a "force" to be overcome when attempting to maneuver and provided and large part of the "feel" we depend in part on to "judge" our inputs to produce a desired result. (i.e. we all know, the further forward you move the CG the greater the inputs (loads) necessary to achieve a desired result..and vice versa).

In other words, the forward CG provided feedback which informed the pilot as to what the airplane was doing and taught him what "feel" to expect when things are done right...or, alas,  wrong.

It is important, now, to note that without flaps there was no "adverse pitching moment" for the pilot to overcome or, for that matter, to provide additional "feel" to him/her.  (we're about to go full circle here).  Thus, it is very important that the CG be forward of the CL to provide that "feel" even if the tail is technically large enough to stabilize the ship with a CG co-located with the CL.

The flapped ship, on the other hand, allows us to take advantage of the larger tail area/arm to move the CG aft to...or even aft of...the CL and still remain stable AND simultaneously add the force required to deflect the flaps to the feel for the pilot...essentially replacing the feel lost by moving the CG aft on the unflapped airplane.

I realize there are a whole bunch of "words" trying to describe the above so let me illustrate the concept with a personal experience that embarrasses me a bit because it is how I came to think about and experiment with the concept.

The Doctor (Medic) design I published in Stunt News years back came well after I had developed a crush on the big area/arm/aft CG concept for my competition airplanes.  I simply decided it would be a good idea to do the same thing with the unflapped Doctor design just to show the old timers who designed all those Ringmaster and Ringmaster variants how much smarter I was now than they were then.  Very carefully insured the design would include at tail area 25% of the wing area and drew plans showing as much.

To make a long story shorter first flights quickly disabused me of the wisdom of the aft CG location.  Although the airplane was flyable, stunt patterns were not pretty and there was very little feedback to inputs...it was a case of move the handle and watch to see what happens and then "un"move it.  IOW, it felt tail heavy and jumpy and far from a good tool with which new fliers could hone their stunt skills.  the solution was simply to move the CG forward and regain the feel feedback from the CG being forward of the CL thus requiring greater elevator deflection and regaining the feel associated with doing so.

The real  bottom line to this exercise is realizing that modern big/long tailed stunt ships allowed pilots to utilize all the positive features of the aft CG--improved maneuverability particularly in bad conditions with proper feel feed back provided by the force necessary to deflect the flaps.  A real win win!

Ted

[Target]

Hmmm, Interesting, Ted!!


So, how did the Medic fly once the CG was moved forward? Did the CG need to be proportionally further forward to the increase in tail volume to get the feel back?? In other words, did you have a larger spread between CG and CL with the long tail moment and area than you would have with the shorter arm and smaller tail area?
I would think that the longer arm, and larger tail would still be a success, since I would think that it would provide more stability and also pitch damping for stopping rotation.


In sailplanes, more tail volume is great for low speed flight (thermalling, and on landing approach), but it is somewhat draggier. Less tail volume is fine when your sailplane is rocketing along at 100mph, you don't need a lot of authority, and less is less draggy in straight line flight. But you have to land eventually (Right?!).


I hear you on the AR, the sailplanes have it all there, but they need it. It would be interesting to see what G forces are generated in a stunt ship. Has someone measured? I bet they have. I would guess 10-15g's on a hard corner? I would guess that an F3F or F3B sailplane might see more than that.

The sailplanes that I am more skilled at flying (slope) actually frequently have HIGHER wing loadings than a lot of stunt planes, when I have them loaded up with ballast.
Thermal planes they are not, and while an empty one of these 3 meter span carbon fiber monstrosities weighs "only" about 70oz, we regularly double, or more than double that weight by adding brass, lead, or tungsten ballast to the wings on the CG. Max allowable surface loading is @ 25oz/sq ft. Max overall weight allowed is 5Kg.

It's always fun to throw a 170oz plane off of a cliff in 25+ mph gusting wind in front of a crowd of people. What could go wrong? At least there is already 25mph airspeed on the wing, and if pushed away from the cliff face safely, there is some instant altitude. Yay! Then you have a whole 30 seconds to build energy and speed and get off and back on the course or the clock starts without you, LOL.


Here is a video, worth a billion words- (It's 100 meters end to end, you can hear the "beep" when the cornerman sights my plane crossing the base lines).



The thing that I LOVE about stunt is that I have a lot to learn. That keeps it fresh for me.
Thanks for the explanations above!!


Kind Regards,

Target