Question about flat bottom wings. If the stab (flat) and the wing (flat bottom) are both resting on a flat surface, do they both have an angle of incidence of zero?

Should be. With this new plane I'm building the wing and stab were almost dead on and it took next to nothing to get them set.

No because the angle of incidence on a flat bottom wing is not parallel to the flat bottom unless you have a very, very sharp leading edge. Rather the incidence is measured as a line throught the T.E. and the center of the L.E. radius. This is illustrated in the example below. The bottom of the wing is set at zero and the red line which indicates the true angle of incidence can be seen to be at a degree or so positive.

Bulls eye levels are really nifty for getting the horizontal stabilizer flat. These are just round discs that have a bulls eye in the middle while looking down on it. Simply lay one or two (one on each side of the vertical stab) on the horizontal stab, get the bubble in the center of the bulls eye, and the tail is level. Use whatever you like to keep the plane secured in that position and you will have both hands free to work with the wing. Just keep the bulls eye levels on the tail to check from time to time to assure that the tail end did not move. These things are like two dollars each and your friendly home improvement store should have them.

Incorrect. When it happens, which is rare, it's a coincidence of the design. An extreme example to disprove your statement is a seaplane with a pod-mounted engine, like a Seamaster. It has a big angle from the prop to the stab.

Pkoury is also correct, tony0707. The OP describes a 0/0 relative incidence, both wing and stab are 2.5 positive to the ref or datum line (which is highly suspect to start with).

It's very unlikely the plane has been altered significantly from the plans. OP has described it as 'very well-built'.

Put some fuel in it and go fly !  [8D]

Hmmmm! Except in knife edge flight. Neither wing nor stab is doing much lifting in that attitude.

Not so certain about "no airplane flies at zero zero....." either. Certain wing types generate considerable lift at zero AoA. Same is true for different stab sections, other than symmetrical

Isn't "decalage" usually defined as the difference between the angle of attack of the wing and the stabilizer? It doesn't make any difference as to where or what the reference line is. Neither a wing nor a stab can have an incidence unless it is relative to some other plane.

Close. Originally, was the difference in angles for biplane wings.<a href="http://en.wikipedia.org/wiki/Decalage">

http://en.wikipedia.org/wiki/Decalage</a>

Grey beard a swoose is a tough build ,i have seen many that did not set them up the way you have.The result was them never getting off the water and if they did, it was for a few seconds. lol Very nice build Grey beard ! joe

Hi
I have built most of my planes for 20 years with : a zero incidence stab-zero incidence wing and zero incidence engine alignment per the very wonderfull trainner i had the very good fortune to know and love who was flying for 30 years before i met him
They perform great for me that waymy planes ALL fly on rails when trimming flights are completed
Now the engine is pulling the wing and stab thru the air all on the same demensional planewith less resistance (all pulling in the same direction )OR do follow the instructions on incidence on the plans (especially for bi-planes )
My elevator when trimmed after a flight is always level ( or an incidence adjustment is required )
If you are carring up trim in your elevator after you trim the plane for the first flightsyour wing has DOWN incidence in it
If you are carring down trim in your elevator after you trim the plane in flight your wing has UP incidence in it
The amount of up or down trim you are carring is the EXACT amount you need to SHIM the wing
Example- If you are carring 1/4 inch down elevator ( after you have trimmed the plane in flight ) that indicates your wing is at 1/4 inch positive incidenceyou need to SHIM the wings TE 1/4 inch for the wing to get back to zero incidence
Example twocarring 1/4 inch up elevator indicates you wing is carring 1/4 inch down incidenceyou need to SHIM the front of the wing UP 1/4 inch for the wing to get back to zero incidence
In both cases above after the proper SHIMING is done the stab - elevator and wing will all be flying level ( elevator will have no up or down trim any longer ) when plane is retrimmed on its next flight
Having the elevator carry no up or down -but be NEUTRALwhen you trim is were you want to be
As a rule all incidence settings wing and fuse squaring should be done in the shop prior to the first flight
The first flight will tell you a lot about how close you are to perfection Or if an ajustment is required for flying surfaces to trim out as they should
As a general rule I think it often takes 5-10 flights on a given new plane to work out the BUGS of a given new aircraft
You need to trim out get the landing gear to work (sometimes )get engine to run as it shouldrecord the way a given plane flys and responds to controls and manuversnote CG location type servos and RX in plane prop size engine RPM ETC-
With 20 plus planes flying i keep an index card for each plane with notes that explain any ODD STUFF i need to know about each plane and any maintenance that was performed or needs to be performed ( all spec's related to flying are recorded )
Not remembering what was done or needs to be done could be COSTLY
Sometimes with a lot of planes it is YEARS before i get back to flying a given plane but no problem -all I need to know is on the index card in black and white (do write up the index card in PENCIL so changes can be easily made to your recorded info if this will work for you )
Notes for each plane keeps me knowing what each plane requires and what i can expect from its performance even if years of having the plane hang on the wall have passed when i decide i would like to fly it again
After returning from a day at the field-i will sit and make detailed notes as to all the events of my days flying
I find this to be the best possible way for me to determine all kinds of ways to improve a planes performance and realize what maintenance should be performed to improve the plane i am flying so i can move foward with the planes performance
Any and all issues are noted so they can be adressed before the next day out
HAPPY LANDINGS !
Regards Tony

Tony that's how I was taught.

Gary

I'm not totally convinced that winding up with a neutral elevator trim is the goal for all planes. For some designs, it's helpful to wind up with a little down which makes the plane pitch down at high speed and go a little nose up at slower speed, making it fly straighter at a broader speed range. If the decalage is set for a neutral elevator at any given speed, that self-adjusting effect is lost.

CHAD, would this qualify as a flat enough, sharp enough leading edge??
Just screwing with ya. It isn't often on a clark-Y that I would have a LE that sharp and flat. Mater of fact, without the rounded LE is this a true Clark-Y? Never mind, that is another can of worms of a question.
The Swoose is an easy build if you have the original build article from 89 and I do. Nick shows the wing jig he uses on a gull wing and it is great. Wish I had thought of it when I was building a Corsair!!!!!!!! One jig builds both wings and it is a normal one piece wing halves, makes any gull wing easy and the Swoose even more so.

Decalage is a French word that means displacement of two temperatures or measurements; also absence of concordance between two things.

Hence, it can be used in both cases, where two angles diverge.

I would like to add to the above discussion that stabs fly within the downwash produced by the wing (not for canard layouts); therefore, they normally have negative AOA (producing negative lift that compensates for wing's pitch moment), even when the incidence angle is set as neutral.

What he's tryin' to say is the tail pushes down and the wing pushes up.   

That's about as close as you can get to flat bottomed Gray Beard! The Swoose has to be one of the most classic of r/c designs. A real challenge for the builder but the finished product will be most satisfying I'm sure. Best of luck with it.

People keep telling me it is a classic and a tough build? Everyone seems to love the Swoose, yet I have never even seen one at a float fly or any other events, ever. The build is no different then any other plans/scratch build so far. Maybe when I get to the floats it will become hard?
I'm open to any input or knowledge of this plane, I have never seen one. That is one of the reason I'm building them. Mine is glow power and the one I'm building for my buddy is electric, should be fun getting them both set up and flown. Can't wait for maiden day. Don't know if I should maiden from water or land first?

Land is easier to pick up pieces from in my experience.

I guess then that it is a credit to designer Nick Ziroli that the airplane appears very complex but really is not. I think it would fantastic blown up to about 120 inches!

I have seen some video's of a big one but it just taxied around. It's just a box fuse. The wing could be hard if you didn't know about the jig Nick showed in the original build article in 89.
Maybe someday I will build a big one but first I would like to see how these two fly. I have heard about an issue with the skirts giving the plane too much side area. That can be fixed with a scroll saw though.
I have found it a straight forward build so far. I may run into trouble with the floats?
It was first seen in the 1946 MAN and Nick re-designed it for RC and made it bigger in 89 so you now have ailerons.

I have seen 3 or 4 of them on water in my travels and like i said if not set up right they are a pain in the ars.Two of the ones i seen took off to early and tip stalled back into the water after a couple try's on getting them broke loose from the water. One was tail heavy the other looked like incidence ishues . I seen one that was fiberglassed and painted and it flew like a brick with gull wings. There was one that was built very light and covered in silkspan ,it was built by a old free flight man and it flew great with no problems at all. joe

Mine is fully sheeted and glassed then painted, that is #1, #2 is built to the plans but I'm sure the aft section will be lightened even more then I have built it because it will be covered with, Probably SolarTex then the fellow is going with electric power. #1 will be kind of easier to CG because I'm using an SK .80 with a Bisson Pitts muffler. The Ziroil Build does state his came out way tail heavy, that's why I choose such a heavy power plant. I also have some sub-C battery packs. The build is still straight forward though, nothing hard about it at all.