Rendegade

Hey guys, just thought before I start adding more fins and things to my current ship, while the new one waits for me to pluck up some courage and throw so balsa at it, I thought a bit of a discussion about fins, would be worthwhile.

This includes ALL fins, not just canalisers.

I'm sure I'm not the only person to to be interested in this either.

My question relates more to sub fins this fine day. I guess the first place to start would be Nat Penton's planes, as they have a huge sub fin, (and corresponding dorsal fin) to give very effective side area, as I understand it.

Now I've also noticed that the japanese have been fiddling with sub fins, albeit smaller, and I'm starting to wonder whether they'd work well for me.


I have a long and low old girl with a canopy almost on the trailing edge of the wing, and I'm thinking of adding sub fins (I'm thinking about 2inches high and 4-5inches long) oon the belly pan forward of the canopy almost under the landing gear, set at 45° like a v tail, to increase my CP forward and give me a bit of side area.

Is this area below the CL going to help or hurt me? Is it going to do anything at all?

67685

Hi,

I am not sure if this is what you was thinking of, but it is for sure a whirlygig..

In the picture you can see my Bondary-layer-turbulator, inspired by a German WC F3A pilot ; G-Ulsamer. (present on his model at 2009 WC ).

I guess many of us have tried a turbulator in different applications , but for me, this position ( near the LE ) was new for me. Time to test this one.

In tried different type of turbulators in slightly different positions, and i finally came up with this one ( ref pictures). It is installed on my Integral; my 1-choice comp bird for the next years P-11.

It is a self adessive velcro ( hard side of it ). I found the velcro interesting by it`s construction, since it is high, but not completely sealed; letting the air pass throuh it and not in a semi-paralell direction acroos it. At the same time make a better whirly-effect to the bondary layer. That was at least the thought behind it.. Theory and real life can be different, so only one way to find out, besides; no effort or time spend if no result, easy to install / remove

Testing was done in calm / little wind performing P-09 + some P-11 manouvers, since i knew how the bird react in differents situations, thereby easier to compare the effects.

Hmm, i must admit i was suprised in a positive matter.. The bird started to change behaviour early in the test`s using different types of tapes, but the velcro was defenetly the best.

It got a nice "lock-on" feeling, like it was "gyro stabilized" so to speak.. In other words ; Stays in position, not so nervous and sensitive, soft, but still crisp at higher inputs.. More predictable stall with no noticed increased speed.. At the same time, no side-effect`s, as far i am able to see.. The effect is different than the thick TE, which to me feels more like an expo, but not the same stabilized "lock-on" feeling as the velcro.

What can i say; the German guy is defenetly into something here. So far, i will keep this one for sure, suits me and my liking,

Just my personal experience and taste.


Kjell Olav

vbortone

My Feedback: (2)

Subscribing.

Vicente "Vince" Bortone

Rendegade

Kjell, wow, I have to admit, that's not quite what I was after, but having said that, what you've done is definitley inspiring! how wide is the strip of velcro? I assume from the pictures it is 4-6mm?

BTW, a whirlygig is the same as a thingamabob,thingamagig and possibly a whatsit.

wattsup

My Feedback: (1)

Renegade & 67685, What you have concocted cannot be any worse than some of the other gimmicks we have all seen to help sell a pattern plane. I think you we agree with my ongoing statement of truth, You still gotta fly it! Regards___TNWalker

Rendegade

TN_walker, I think you're right.

I may just have to go out on a limb and add some crap to my plane.


btw, every time I see your user name, I think of T-bone Walker, one of the best blues men in history.

And this, at least here, is a stormy monday.

wattsup

My Feedback: (1)

Renegade, I also heard that if I take apply a strip of velcro to the antenna of my new Airtonics SD-10G Tx, "Magical
things will happen"! You are correct, T-Bone Walker was truly a great R&B artist. Regards____TNWalker

67685

Hi,

.. :-) ... translating words to Norwegian. Whirly - gig :-).

... yes, the statement " you still gotta fly it" is still valid, but we are all open for improvements to make it easier :-). No effort or time spend on this one, easy to try, no cost.

Some detaljs and pictures : The strip is 4.5mm wide to be excact. Start from root, all the way to the tip ( where the tip-radius start ). Distance from LE : Root: 37mm , Tip: 18mm ( both measurement in middle of tape widt ).

If any interest of type

Type : Tesa velcro p/n 55225-00000.
www.tesa-velcro.com



PS. The owner in the picture is really convinced! :-)

Rendegade

hehe, maybe I should just stick one of those bumper stickers that say "magic happens" to my transmitter, and I might be able to do the figure M in the p-11 properly!


hehehahaha


although, at this point I'm not adverse to selling my soul to fly better,

cheers

Willie Brown, aka Rendegade...

Hans Meij

Hi Kjell,

Good idea to try.
Googled a bit and found this article from Martin Hepperle.
http://www.mh-aerotools.de/airfoils/turbulat.htm
Have you experimented on position and height? The graphs do give some extra insight.

I see that you have a large Canalizer mounted. Lately I changed the canalizer on my Synergy from the standard 20cm of CPLR to about 30cm. The effect of a responsive rudder and easier control of rolls increase even further.

Regards,
Hans

JAS

My Feedback: (2)

All sorts of thingamajig's...

xcead

hmmm....what about this one ? ( useless if you ask me...)

serious power

Guys,
Great idea; this thread !.
I have not used a cannalizer as yet.
I am wondering ;If the cann,, increases rudder authority and a 'fat' rudder TE decreases sensitivity why some people do both ??.

Brian

mjfrederick

By sensitivity they mean the "touchiness" around neutral, authority is referring to the power at full deflection. For instance, the strake that Bryan Hebert developed for the Valiant (Jason's first picture) was done because he didn't feel the rudder had enough power for stall turns.

Jason Arnold

Has anyone ever done wind tunnel testing on a pattern ship? That's probably the only true way to confirm one way or another if a gadget actually works or not.

In a few years our planes may actually look like a Formula 1 car with all the aero thingys on them. Yuk!

Cheers
Jason.

serious power

Hi,
I choose to use those terms as they seemed to fit the best with the expressed benefits of both.
However the cann,, guys are claiming improved response around centre,less rudder for rolls etc.
I'm flying a Zeque and you just lean on the rud,, stick for rolls and knife edge as is.

Brian

67685

H Hans,



Hi Hans,

Thanks for the article, good detaljed reading about the subject. The turbulator has been used in many applications, well documented.

I have tried the turbulator in other positions on other planes in the past, but only this forward position on my Integral.
But i did try differents height`s. ( not velcro though ).Seems that about 1mm is enough ( relatively thin bondary layer in this area ). I tried a " friction type of tape", like the one used for step`s etc, 0.8 mm high, works good. The present velcro has a base at 1mm, and total height of 2.5mm.

The cann is 31cm wide, 9cm at root. I guess the size is ok, at least it works good. positioned -0.5` to -1.0` ( relative to datum-line). Besides of better knife-edge control, stall-turns are more predictable to perform.

Kjell Olav

JAS

My Feedback: (2)

I added the T on the Integral for 1 maneuver. It did require less rudder for rolling stuff, but I only did it for the KE loop. Didn't notice any change in stall turns.

Rendegade

that'd sound about right, I'd assume that the canaliser would have decresased effectiveness at keeping the airstream straight and over the tail at low airspeed.


Love that little nosealiser, but yeah, doubt it'd work.

guille2006

Very nice all;
You know, as aeronautical engineer I still did not found a good (but a REAL good) explanation of how does the T cann. works. I cannot figure out even...
I'd appreciate if anybody explains me (and all).
regarding to turbulators on the wing; we can also use tapes (of certain thickness) with the same result but less Parasite Drag. In Abbott's book and "summary of low speed airfoils" (several authors) there are many data regarding to this turbulators on laminar flow foils. We can use also Turbulent foils with kind of simmilare resullts...
Thanks, great thread!!!

PS: Should I give back my diploma?!?!? IT COSTED ME A LOT!!!!

apereira

Pattern planes really are on the edge of the perfect flying ship, so a wind tunnel will not do much as the maneuver transitions will be the most important factor and that can not be done in a cost effective way. And that's why even though full scale airplanes that are designed using a wind tunnel, need to have a test flight program designed to prove the design with real conditions and on maneuvers that can not be tested on the tunnel.

So, flying the pattern plane is the only way to fine tune a design. Anything that can be done aerodynamically to improve a design and make the airplane fly better and easier is the way to go. A very good friend of mine and flying buddy told me a while ago that expo and mixes was for bad pilots that could not do the correction in flight, of course he uses all that now and never said that again, of course that happened when he started to fly pattern.

Regards

Jeff Boyd 2

Then there is Silvestri's contribution to the World of thingamajigs . . . apart from looking like a 'toast rack', I am sure it has some benefits. I know, TNWalker . . "you still gotta fly it"

Also, the little shape added to the wing at the end of the aileron. Interesting gizmo, that one . . not sure if it's a fin or a whirlygig . . Hmmmm ??

Cheers, JB

rcpattern

My Feedback: (45)

Dave Lockhart has been running fences on his Prestige as well.

Arch

flyintexan

My Feedback: (1)

Jeff, my guess would be that its a whirlyfin.


Nat Penton's work goes back so many years. His simple solution comes from a simple understanding of center of lift, cg, and rotational airflow. Keeping the center of lift and cg near one another (in all axes) promotes more pure flying in all axes.

Small whirlyfingigs located some significant distance away from the cg can help certain issues, but if made large enough to have significant effect in one axis, will likely be a detriment in another.



-mark

mups53

My Feedback: (41)

Mark how recent is that photo? I like the idea that the thingamajigs are more effective near the CG. To me what youyr saying makes sense. Do you have any pictures of your Pentanthelon to post? I still think your plane is full of great innovations and looks to me like it flys on a rail. Thanks, Mike Mueller