Trim flap versus tip weight?

[Andrew Tinsley]

    Thinking of the lack of tip weight box on an Intrepid XL (a previous thread). I remember that 40 years back, some folk put an adjustable trim flap on the tip of the outboard wing. This was supposed to eliminate the need for tip weight.
     It sounded a good idea then (less all up weight!). However it does not seem to have caught on. What is the downside, speed dependency?

Regards,

Andrew. 

[Tim Wescott]

Gravity vector independency -- the roll will always be in one direction with respect to the plane, i.e. out when you're flying upright, but in when you're flying inverted.  Tip weight always works to make the outer tip drop toward the center of the earth, regardless of whether that's toward the wheels or toward the canopy.

I do see roll taps advocated if the plane has a different tilt upright than inverted, though I'm not nearly advanced enough to have actually needed such a measure.

[Andrew Tinsley]

   Why didn't I think of the obvious. Inverted would be interesting. Think I must be in need of brain surgery!

Regards,

Andrew

[W.D. Roland]

   Why didn't I think of the obvious. Inverted would be interesting. Think I must be in need of brain surgery!

Regards,

Andrew

HA!
I'm Next! (Brain surgery)

It's possible that a hinged tab with heavy counter balance would do the trick.

Just a thought, now where is that brain surgeon again?

David

[john e. holliday]

Seems to me that years ago when I was mucho younger, reading a construction article on a stunt/sport plane in which that was the cure the designer had.  It was a hinged tip flap hooked to a swing weight that was supposed to keep the wings level during maneuvers.  I don't beleived it caught as being not dependable.   

[Larry Fernandez]

How is an adjustable trim tab going to help, if the outboard wing is flying high both upright and inverted?

Larry, Buttafucco Stunt Team

[George]

Actually, I think most who add a trim tab are compensating for a wing warp.

George

[W.D. Roland]

Doc
You jogged another memory loose!

Hints and tips?
A page every month in American Aircraft Model(Was there a magazine of that name?)
The page used sketches for hints and tips.

What I remember is the tab was mounted on a frame like 2 miniature tail booms on a combat.
This let the counter weigh fit between tab LE and wing TE.
Would be sort of ugly on a stunt plane.

Does this sound familiar to anyone( memory test)

Anyway another quick sloppy sketch to show how the idea works in a version that might look better.
More weight= more effect, less=less

[Larry Fernandez]

Doc
You jogged another memory loose!

Hints and tips?
A page every month in American Aircraft Model(Was there a magazine of that name?)
The page used sketches for hints and tips.

What I remember is the tab was mounted on a frame like 2 miniature tail booms on a combat.
This let the counter weigh fit between tab LE and wing TE.
Would be sort of ugly on a stunt plane.

Does this sound familiar to anyone( memory test)

Anyway another quick sloppy sketch to show how the idea works in a version that might look better.
More weight= more effect, less=less

Again I ask, How is this going to correct a plane that flys outboard wing high, both upright and inverted?

Larry, buttafucco Stunt Team

[RandySmith]

Again I ask, How is this going to correct a plane that flys outboard wing high, both upright and inverted?

Larry, buttafucco Stunt Team

Very easy Larry..... Ya make the trim tab the exact weight of the outboard tip weight... Silly question 


Randy :-)

[Steve Fitton]

Doc
You jogged another memory loose!

Hints and tips?
A page every month in American Aircraft Model(Was there a magazine of that name?)
The page used sketches for hints and tips.

What I remember is the tab was mounted on a frame like 2 miniature tail booms on a combat.
This let the counter weigh fit between tab LE and wing TE.
Would be sort of ugly on a stunt plane.

Does this sound familiar to anyone( memory test)

Anyway another quick sloppy sketch to show how the idea works in a version that might look better.
More weight= more effect, less=less

Those look like external mass balances that would be used on an aircraft to control flutter issues, not wing up/down issues.  Howard Rush could probably post you a link to the requisite paper that explains their use in full size aircraft.  For me, I use tipweight and either a flap tweak or roll tab adjustment for roll trim.

[W.D. Roland]

Yep!
That is also how you mass balance to stop flutter. Works on Flying Stabs also.
Also used to reduce control stick forces.

On the trim tab, (not connected to controls) if out board wing is high in level 1G flight the weight moves the tab in direction of correction.
Same inverted.

During maneuvers and increased Gs the effect becomes stronger.

This type of tab is not to cure warped wings although it could replace tip weight.

Tab on outboard wing.

inboard tab would do opposite.

Also have to consider what the difference in pressure top/bottom would cause.

Lots of things need to be considered but this could be made to work for a outboard wing high in inverted and high in upright.
Or opposite on inboard.

This could work better than tip weight but possibly not. 
Someone would have to try it to see if it works in real world.


David

[Randy Powell]

Seems to me that part of the reason for tip weight is to balance the weight of the leadouts and lines.

[Tom Niebuhr]

Jim Vornholt flew the Charlie Mackey design "Carousel" to a Nats win. The "Carousel" had a outboard flap section with a small counter weight that was forward inside the wing.  I don't know how well it worked. I know that Jim refinished the airplane. I have heard that he is possibly building another "Carousel".

It would be interesting to have Jim's comments. Did he really use the counterweighted flap section, or did he disable it? Jack Sheeks and Jim see each other often, possibly they can comment here.

[W.D. Roland]

Seems to me that part of the reason for tip weight is to balance the weight of the leadouts and lines.

Thats what I plan on sticking with, At least until the understanding of Stunt airplane trim sorts itself in the dense Grey matter up top.

At this moment though I think that less tip weight and some small amount of effect from this type of tab would help my Chipmunk. But ..........maybe one day.

David

[Larry Fernandez]

Very easy Larry..... Ya make the trim tab the exact weight of the outboard tip weight... Silly question 


Randy :-)

Thanks Randy!!!!

Thats why you are a top 5 flyer and I suck !!!!!!!!!

Larry, Buttafucco Stunt Team

[Bill Little]

Jim Vornholt flew the Charlie Mackey design "Carousel" to a Nats win. The "Carousel" had a outboard flap section with a small counter weight that was forward inside the wing.  I don't know how well it worked. I know that Jim refinished the airplane. I have heard that he is possibly building another "Carousel".

It would be interesting to have Jim's comments. Did he really use the counterweighted flap section, or did he disable it? Jack Sheeks and Jim see each other often, possibly they can comment here.

Hi Tom,

Jim said he is actually refinishing/repairing the original Carousel.  Last time I spoke with him, he was painting it.  Said he would take it out one time and then retire it.   he has been a great help with the Airon.  If I can remember, I will ask him about the flap counter weight.

BTW: Jim said that the Airon came about after his first Junior NATS win (1960) because he had done a poor job of the finish on the Carousel.  He got with Bernie and came up with something that would look really different, and he put a better finish on it.  The Airon gave him his second NATS Junior win (1961).  Of course, he was only around 13 tears old then!  

Bill

[Tom Niebuhr]

Bill,
Looking forward to Jim's comments.

[John Ashford]

I have used a combination of tip weight box and adjustable trim tab on all my own planes and all my customer planes for the past eight years.  Both features accomplish different things and need to be worked in concert for the best results.  I frankly don't think it is an "either / or" issue.  You need both.

Later,  John