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Outdoor Free Flight Forum => Catapult Launched Gliders => Topic started by: Sailaway on August 27, 2018, 05:15:09 PM



Title: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: Sailaway on August 27, 2018, 05:15:09 PM
Sorry for the very novice question. But how does one adjust incidence in the CLG with Tumbling Pigeon DT? I see clearly in the DT where the  latter boom pops up. Same as in TLG. I cannot grasp the concept after seeing so many plans here as how the tail incidence is finely adjusted. Appears the 2-56 screw tapped at the TE of the wing will only move the TE of the wing up as the boom is fixed ?? What am I missing here? Thanks in advance and as always for helping me understand this as I am for the right reasons moving to the Tumbling Pigeon DT, mainly to build light.

Cheers.


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: danberry on August 27, 2018, 08:12:42 PM
Up or down. That's what it does.


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: Sailaway on August 27, 2018, 09:34:03 PM
but how sir? the 2-56 nylon screw is at the wing Trailing Edge and what appears to me is that the front end of the carbon boom is fixed. So the TE of the wing moves up or down and not the elevator? I am missing something or not reading the plans right? Help me understand a bit further please


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: flydean1 on August 27, 2018, 10:02:37 PM
Lets see now...If you can move the wing TE up and down, why ever would you want to move the elevator.  Most TLG/CLG gliders don't have one separate from the stabilizer.  You're changing the relative angle of the wing relative to the stab.  It works really well, and lasts a long time.


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: danberry on August 27, 2018, 11:09:20 PM
Yes the wing moves up or down as necessary.   Tiny adjustments have big consequences on a CLG. 1/8 turn on a 2-56 is a big adjustment here. If you run out room needing to lower the TE ….. make some room.
These things fly at less than 1/2 degree decalage. Give or take a foot.


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: danberry on August 27, 2018, 11:10:34 PM
If we knew where you were, we could likely point you to help.


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: Tapio Linkosalo on August 27, 2018, 11:53:49 PM
These things fly at less than 1/2 degree decalage. Give or take a foot.

Decalage is the word. Difference in angle between wing and tail. When you adjust the model (e.g. by changing the tailplane), what you essentially do is adjust the decalage. Hence it does not really matter if you adjust the wing or tail angle, the outcome is the same. Move wing trailing edge down does the same as moving the tailplane trailing edge up. And vice versa.
 


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: Sailaway on August 28, 2018, 12:07:03 PM
Thank you all. This is a new concept for me. But thanks for confirming that the Carbon rod boom is stationary and the entire TE of the wing moves up, however small ( 0.5 degrees or there about) that gives the same effect as up elevator. Just one thinks we have the needed knowledge, then it is great to change the paradigm. Will try out building now.
Cheers and thanks again.


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: ram on August 28, 2018, 02:49:06 PM
the entire TE of the wing moves up, however small ( 0.5 degrees or there about) that gives the same effect as up elevator.

It's the opposite effect.


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: flydean1 on August 28, 2018, 02:57:26 PM
Note reply from Ram. 

Also from DanBerry.  If we knew your location, we might get you to someone who can save you a lot of frustration.


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: mike on August 28, 2018, 03:04:56 PM
I'm confused here.  Please explain 'tumbling pigeon DT'.  I've never heard the term.  I'm familiar with the tip up wing DT often seen on TLGs - mine's in the picture below.  If it had an adjustment screw, it would be screwed through where my fingers are with protruding end resting on the main fuselage.  If screwed further through its threaded hole in the 'wing' part of the fuselage, it would serve to jack the hinge apart, increasing the wing incidence relative to the tail.


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: ram on August 28, 2018, 03:26:25 PM
I'm confused here.  Please explain 'tumbling pigeon DT'.  I've never heard the term.  I'm familiar with the tip up wing DT often seen on TLGs - mine's in the picture below.  If it had an adjustment screw, it would be screwed through where my fingers are with protruding end resting on the main fuselage.  If screwed further through its threaded hole in the 'wing' part of the fuselage, it would serve to jack the hinge apart, increasing the wing incidence relative to the tail.


Wing pivots at the front vs the back causing the "tumbling pigeon" action.  There are plans here:

https://www.amaglider.com/?p=view&a=stans-stuff_2016-2017

Rey


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: NormF on August 28, 2018, 03:40:15 PM
The “tumbling pigeon” effect is a result of the rear of the wing raising instead of the front (as in your photo). The glider tumbles down and does not stabilize or parachute down as in a tip up tail system. An example can be seen in Stan’s catalog. https://amaglider.com/?p=view&a=stans-stuff_2016-2017

Norm

Rey types faster!


I'm confused here.  Please explain 'tumbling pigeon DT'.  I've never heard the term.  I'm familiar with the tip up wing DT often seen on TLGs - mine's in the picture below.  If it had an adjustment screw, it would be screwed through where my fingers are with protruding end resting on the main fuselage.  If screwed further through its threaded hole in the 'wing' part of the fuselage, it would serve to jack the hinge apart, increasing the wing incidence relative to the tail.



Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: mike on August 28, 2018, 03:48:29 PM
Thanks guys, hi Norm!  Twice beats not at all!
Fully understand now - thanks.
 


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: danberry on August 28, 2018, 07:39:03 PM
Note reply from Ram. 

Also from DanBerry.  If we knew your location, we might get you to someone who can save you a lot of frustration.


Literally EVERYONE that I know who flies Free Flight is willing to offer help to anyone.

First-person help is the best.


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: Sailaway on August 28, 2018, 08:40:03 PM
Hi Dan,I am in western New Jersey almost Phillipsburg, bridge across Easton, Pa. Would love to hook up with FF flyers.  But thanks to all of yu at this site for all the support.
Cheers,


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: danberry on August 28, 2018, 09:14:26 PM
I am wracking my feeble brain thinking of someone closer than NYC.
Coming up blank so far. Bob Sifleet move away from Pennsylvania. I think.
The field at Wawayanda gets used but that isn't real close to you.


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: flydean1 on August 28, 2018, 10:01:38 PM
Maybe someone from DC Maxecuters is around there.  I think they have a website.  Mostly FAC activity but many have expertise in duration Free Flight (Always Capitalize).


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: Tapio Linkosalo on August 28, 2018, 11:50:37 PM
entire TE of the wing moves up, however small ( 0.5 degrees or there about) that gives the same effect as up elevator.

"ram" already pointed out that it is "the opposite effect", but let me explain that in more detail. What we discuss here is the angular difference between wing and tail. Also called as decalage. Hence, moving the TE of wing down has the same effect as up elevator.


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: Sailaway on August 29, 2018, 10:58:59 AM
Thanks Tapio. Understood, So as you see my crude drawing, there is enough room to get the TE down for 0.5 degree or thereabouts "Decalage"  effective "up-elevator).

Dan, i will contact Wayanda club in  NY. great guys i had met up many years ago.


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: Tmat on August 29, 2018, 02:19:11 PM
You can get more decalage ("up elevator") by sanding the bottom of the wing mount to give more movement down. If required of course.

Tmat


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: USch on August 29, 2018, 02:31:08 PM
Appears the 2-56 screw tapped at the TE of the wing will only move the TE of the wing up as the boom is fixed ??

I think you got it completely wrong. The wing has to be firmly glued to the green wiggler in your design. The 2-56 screw can be screwed in or out to push on the tail boom and changes the decalage. If you screw "in" (clockwise) you push the tailboom a little down, same as reducing the decalage. Screw "out" (anticlockwise) you increase decalage.

But thinking it again there is something in your design which sounds wrong. The tailboom cannot be fixed as you write, otherwise how could the Dt work. The tailboom has to move in repspect to the wing the get a decalage of about 30-45° for DT'ing. On your design wing, tailboom and tailplane would move together around the alluminum rivet, leaving the relative position of wing and tailplane unchanged.

Urs

PS: might be total B...S... what I wrote  ???



Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: mike on August 29, 2018, 03:21:55 PM
Urs, the green part, and the wing joined to it, pivot around the rivet to raise the TE of the wing - the model then tumbles down. there's no stable descent like a conventional DT.  It puts the wing into a negative angle stall.


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: USch on August 29, 2018, 05:51:35 PM
Sorry for that !!!
It was clearly a matter of hitting first the keyboard and then switching on the few remaining grey cells  ;D ;D ;D

Urs


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: danberry on August 29, 2018, 06:42:47 PM
Thanks Tapio. Understood, So as you see my crude drawing, there is enough room to get the TE down for 0.5 degree or thereabouts "Decalage"  effective "up-elevator).

Dan, i will contact Wayanda club in  NY. great guys i had met up many years ago.

Are you a member of NFFS?


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: Rewinged on August 29, 2018, 08:18:18 PM
A little late, but in case more pictures help...  This is of a well-trimmed glider, and you can see that there is plenty of room left for adjustment. Since I don't like constructing DT systems, I build the wing and tails but buy the largely completed fuselage from Stan Buddenbohm.


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: Sailaway on August 30, 2018, 10:35:17 AM
Those pictures makes the concept real clear to me. Thanks for taking the trouble. I did order the glider from Stan to learn. I figure a 0.5 or degree  down TE should be about a  32nd on a 3.5 inch chord. So there is enough place to make the whole TE go down as needed. In the photo it appears your left side of the tail is way higher. Is that for the turn or avoid the thumb strike? Or a dihedral on tail? 

Again thanks to all of you. Dan, yes  I just joined the NFFS.


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: danberry on August 30, 2018, 10:44:23 AM
Good deal on joining NFFS.

Stab tilt induces glide turn. It will turn toward the high side of the stab.
The story on how this got figured out is a good one.


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: flydean1 on August 30, 2018, 12:11:32 PM
The story on how this got figured out is a good one.

Well Dan, let us in on it. ??? ???


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: mike on August 30, 2018, 12:17:50 PM
....Stab tilt induces glide turn. It will turn toward the high side of the stab. ....

Birds showed us this one.  Tilting your tail gives a sideways force to cause yaw.


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: Rewinged on August 30, 2018, 01:14:25 PM
Glad the pictures were useful!

Yes, the stab tilt is to help the glide turn.  A contest CLG is typically adjusted with a tiny bit of rudder for the climb, and stab tilt for the glide turn.  (L rudder for a flyer who holds the launch stick in their left hand and the glider in their right.  Just bend the rudder near the fuselage a tiny bit, not higher up on the fin.)

With a rearward CG, (and associated minimum decalage as is present in most free flight planes), the stabilizer will be lifting. With a tilted stabilizer, part of that lift force will be sideways, inducing a turn.

The dihedral in my stab is to help avoid the stab strikng my thunb or finger that were holding the glider.  I was told it wouldn't help, but It does seem to help me.


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: Sailaway on August 30, 2018, 08:42:19 PM
i hurriedly put together a sort of pigeon DT glider to understand the concept. I get it now. Drove to the field to get get a few pulls. On my fourth pull, got a stab strike on me left hand. That was the end time to go home.
So what is your secret to estimate the dihedral on the tail? Can any flat stab be converted to Dihedral. Would i be wrong in saying left side dihedral more than the other to make it turn left after transition ? I think, I will need it too, unless there's a way to adjust( longer?) hold button and the  front hook design?

Just thinking out load, that would it not be great to have V-tail design in such case? Get rid of the rudder ( lighten the tail) and reduce the possibility of stab strike tremendously. However, never seen a CLG with a V-tail design yet.  Just thinking.


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: Rossclements on September 24, 2018, 11:31:50 AM
These guys only use v tails with great success: https://www.youtube.com/watch?v=FNuYjOAwV_E

They have how to's with dimensions and all on their main channel page too.


Title: Re: Adjusting Incidence on a Tumblng Pigeon DT CLG
Post by: danberry on September 25, 2018, 12:08:36 AM
The story on how this got figured out is a good one.

Well Dan, let us in on it. ??? ???


Frank Parmenter had built a new gas plane, finished it on a Friday night. He noticed that the stab was glued on with a tilt but didn't fool with straightening it. Flew the plane on Saturday. It flew with a beautiful glide turn. He was unable to live with the tilted stab and fixed it overnight. On Sunday he had lost the turn. The only change was the stab tilt. The engineer mind took over and here we are.