Cees,

I've been away to our local community college all day because I teach computer classes there and I see that you've continued the discussion.

You must have far better soldering technique than I do, but I'll try to improve. Regarding the stabilizer incidence, I was planning to start at zero/zero as is my usual approach, but at least with this adjustable stab, I can fine tune that before I permanently attach it. I'll be especially watching to see if a little bit of negative incidence is helpful or not. Getting input and advice on a site like this is a wonderful thing.

Greg

A lot of technical help is on this site. My rule of thumb, even on the swept wing Pnoenix', just make sure the nose drop's when you are balancing from the wing tip's. Fly it. I am not an expert here, but it always worked for me, knowng where the CG is, go from there.

Crank

Vince, I am not conVinced yet (LOL)

After reading the posts there is still one question left and Bob will help you with answerring.

What is in your explanation an incidence of – 0.3 degrees of the stab, situation a or b.
The picture is NOT scaled !!!!

For me a negative incidence is a and positive incidence is b.
So a negative incidence of -0.3 of the stab and a positive incidence of the wing of 0.3 degrees results in an decalage of 0 degrees.
(For me a positive trim of the stab results in a nose up ATTITUDE of the plane.)

When b is your negative incidence of -0,3 degrees (not scaled!!!!) then -0,3 degrees of stab and + 0,3 of the wing results in a decalage of 0,6 degrees.



Cees

Greg,

You see, while your are doing other things, I am still busy with preparing the first flight.
It all will be clear in the near future and you can start the first flight with original combat settings.
When you have questions about solder let me know.
Of course 0 - 0 (decalage 0 degrees) I think is the best start too. So it isn't as complicated but now we want to know it all.
O BTW what is a Phoenix, does it start allover again?


Cees

We are discussing negative incidence at the LE, right ? [sm=49_49.gif] Cees, attached is one of my Phoenix'. You have seen these before?

Crank

Cees,

You've got it backwards. Look at any good set of plans that shows incidence, you'll see negative is leading edge down.

The reason for the +.3 wing and -.3 on the stab is simple. A truly symmetrical wing will not fly at 0 degrees. It has to have a positive angle of attack before it will create lift. If you set a plane up 0 - 0 you will have to use up elevator trim to creat the positive angle of attack.


Bob

Bob,


It is no point for me, I only did want to know if you did fly the planes with 0 degrees decalage or with 0,6 degrees. What we call positive or negative does not matter I think.
For normally flying these differences are not noticeable so for Greg no problem he starts with 0 – 0 degrees so 0 degrees difference.
For us there is a difference in vision and this is mine.
A pattern plane with a 0 – 0 degrees adjustment so 0 degrees decalage does have his stability of the down wash. So effective during flight there will be a positive decalage.
Just my vision I count with.
When there is a lot of down wash we se sometimes a negative decalage in the design of the plane but during flight a positive decalage as result of downwash! so a stabile pitch action.
Modern pattern planes often do have stab and wing on nearly same level so more effect of the downwash and more symmetrical effect in normal and inverted flight.

Cees

Vince

Of course I do know the Phoenix , only the rule of thump I will never advice.
A first flight is never a situation of trial and error, so why take risks? Why adjust a stab on 0,3 degrees and accept deviations in calculated cg position?
My advice, if you want a fast check, mark the wingtips with the original CG position and you can use it to do a fast check by balancing the plane.
I have these points on the centre section (bottom) of the plane.
See picture,

Cees

Sorry everyone for being a puppy killer. I posted the incidence info to help those new to the Intruder set up their plane to get the best flight performance right from the beginning. I didn't know that it was going to hyjack the thread and turn it into a thread about aeronautical theory. Use my info as you see fit.

I love the Intruder and when set up right, it's one of the best planes in SPA.

Bob

No apology needed Bob... I am finding the discussion fascinating as well as informative. As far as getting "best" flight performance from the beginning.... I think would just be good luck.

I'm wondering if I can get this puppy into the air by next weekend. It's hard to make consistent progress when "work" gets in the way. BTW, my HAKKO 936 soldering station was delivered today, so I'm good there.

Greg

I've found that luck is something you fall back on when skill fails.

I have no luck so I depend on getting everything right on the work bench.

Bob

Bob,

I am Taurus and Orion related and that was why I did want a second opinion about negative and positive incidence of the stab. I do show a picture of the Orion, the stab adjustment is noted by Ed Kazmirski -3/16 inch, so negative For me a sign to double check values that are noted, also degrees!. You call this a positive incidence!!!!

Simple to make things clear.
Also stab angles in real airplanes are sometimes noted positive for a positive decalage of the plane so negative for you.

About the Intruder:

I do not know the “World Intruder?�, only did have question marks about the 3 degrees.
For me it is clear the original Kirkland Intruder was designed for 0 degrees decalage (picture 2) but also for retracts so all we find on plans is about the plane for “the man in the street� .

In picture 2 I did copy the stab in the symmetrical wing without changing the incidence!!

About “down wash� you will learn in the future just as most of you. It is all forgotten just as the profits of the diamant stab.

Cees

If a person is building from plans or kit it's much easier to set the incidence. With ARFs it's not.

The proper way to set up a plane is to first find the datum line. This is a line that runs down the side of an airplane from firewall to the tail. It may or may not align with the prop shaft. Depending on the design of the aircraft, this line will be above or below the thrust line of the engine. This line is the center of influence for the design. This is also the "plane flying level" line determined by the designer.

A true 0-0 aircraft has the engine prop shaft, wing and stab on this line. Move the wing below this line and the line now becomes the thrust line and the datum line moves down. Move the wing above the line and the line moves up. This line is only important to the designer. For our purposes, all we care about is finding a straight line on the aircraft that is parallel to this line. In many older designs such as the Taurus or a Kaos the top of the fuselage is a good representation of this line. On some newer planes such as Cranks Focus Sport, the canopy hatch opening on top of the fuselage is parallel with the datum line.

Once a datum line or parallel line has been determined all incidences will be set from that line. In modern pattern planes with adjustable wing incidence, the wing is set to +.3 degrees. That is, the leading edge of the wing is set .3 degrees higher than the trailing edge. After the wing is set, the common thought is to set the Stab at least -.5 degrees to the wing. This will be -.2 degrees to the datum (leading edge lower than the trailing edge). I usually try to set the stab -.6 degrees to the wing to cancel out the .3 degrees in the wing. This keeps the datum line "flying level". Due to the negative in the stab the engine must have a negative incidence to conteract the desire of the tail to fly low or drop. Why the engine needs -1 degree when the tail is only .3 is beyond me but experience shows that this is a good starting point.

These settings are only starting points. One cannot determine any variations or changes without flying the plane. The last seven planes I've built have all been set up the same way (including the Intruders) and needed only minor changes. Usually changes where to the engine incidence and CG. The one Intruder still flying has these settings and of all the Intruders I've flown (4 so far) it's the best flying Intruder. Sorry Crank, Mike's flies better than yours.

Later

Bob

Bob ,

Our both stories are complete.

Yours wit 0.3 degrees wing incidence and -0.3 degrees incidence for the stab resulting in a difference or decalage of 0.6 degrees.
When I may believe Vince you do fly the plane some nose heavy, or for at least do start flying this way. Result , your plane will fly level in normal flight but you have to push some down inverted I think.
Your values are all World Intruder related.

My story is general for the midwinger.
When flying a mid winger we normally can count with down wash for the decalage, which depends on the location of the stab related to the wing.
With this downwash we can try if it is possible to fly the plane with 0 – 0 incidence.
Flying this way the CG probably will be some more backwards when compare with yours (decalage 0.6 degrees).

The down wash will generate for me the effective needed difference in incidences between wing and stab (decalage) to have a stabile flight path. (This flight path does not have to be level, but in normal and inverted flight equal.)

For Greg,
I think we did show both opinions and back grounds now to fly the plane well adjusted the first flights. Good luck.

Cees

just make sure the nose drop's when you are balancing from the wing tip's.

My last post, the above is what I was talking about, the tip's. That is about all I know from an aeronautical engineering standpoint.

V

Excellent discussion by all. Thanks for all your input.

ChiefK

Cees

Stay in the classic pattern forum. They'll chew you up in the AMA pattern forum.

My last post applies to all pattern planes.

Bob

Greg,
You are welcome.

To double check the values and my own explanations I did take a look for a better example of the original Intruder drawings. I could not read the characters in the first examples.
Did find them and made a combined picture of what is noted about stab and wing incidence, both zero degrees.

Also did read the construction article of the original Intruder and for me it is clear, 0 – 0 degrees is the basic design requirement of the wing and stab and are not adjustable.

If the World Intruder does need 0.6 degrees decalage to perform, then we have to speak about a different (modern?) plane in my opinion.

First flights? Of course we are all interested, so maybe you want to let us know in the future what your experiences are.

Cees

Cees,

Your input was quite valuable, and your observations were right on. I had a Kirkland Intruder in the 70's, so I am aware that the WM Intruder is a significantly different airplane, but it IS SPA legal, and it will get me back in the air fairly quickly. Now... back to assembling the WM Intruder. I will post again after it becomes air-worthy and I have a few flights on it.

Greg

For anyone who has walked this path before me.... I don't want to use the "included" pushrod wires for the elevator and rudder. I want to use more traditional carbon fiber arrow shafts with wire ends for both of these control surfaces. I believe that I will need to remove the installed "flexible" wire pushrod guides, but they seem to be glued at each fuselage former. Are there any lessons learned for how to get these out with a minimum of damage to the fuselage? I'm also a little concerned about the WM approach to securing the wing to the fuselage. Has this approach using two 4mm screws bothered anyone else?

Greg

Ah, but you have missed an important, somewhat secret, point. If a model is set up trimmed for an initial zero-zero incidence between the wing and the horizontal stab and then balanced slightly tail heavy, the tail heaviness will provide enough positive incidence to the entire airframe for it to fly level both upright and inverted. Ever wonder how guys got their models to do that?


Ed Cregger

Greg - I put together one WM Intruder with pushrod's, an older model. Next one, had the tube's as you stated. I was hesitant, but at the advice of a couple of guy's, and checking out the install on their's, I went ahead and used that method. It is fine, no issue's. Just make sure all your link's, connector's, etc., are up to snuff. The last Intruder, I put JR 3421 SA's in the back, pullpull on the rudder. Again, no issue's, just move the battery pack around a little for CG. With pushrod's, I had to cut the tail cone out at the rear. Then, after assembling the pushrod, insert it thru this opening. There is an inspection hole on the bottom of the fuse back there, to facilitate this process.

I am sure it is not there for this method. All of these procedure's I did, you can find in an RCU thread I have posted, there are many. When inserting the pushrod from the rear, the metal pushrod's, will just spring out, and pop right into the exit hole's. There are many method's, lot of guy's that did these WM's Intruder's, gave me lot of advice, I just copied them all.
Wing bolt's used in all Intruder's I built. Picture's here of nylon wing mounting. Different Intruder's, all the same, you can see, I re-covered them all, glassed fuselage's first, etc. Eventually on all, I switched to the OS 61 SF's, and for the 2.4 receiver's, to 6V - 2150 mah pack's. Little overkill, better safe then sorry.

Vince

Ed, you write:

Ever wonder how guys got their models to do that?

To show Bob a picture of that exiting (FAI) pattern period.
As the Intruder, "warbird look", short nose and retracts.

Cees

Vince,

It looks like you used the original hold-down mount made up of two pieces of 1/8" ply glued together and replaced the 4mm tee-nuts with 1/4' tee-nuts for standard 1/4" nylon wing bolts. Is that correct? I note that there are no gussetts or other reinforcement provided for this hold-down mount - other than the thin ply fusleage doubler. Maybe reinforcement is not necessary. Has anyone seen or heard of a failure with this approach?

re: the pushrods issue, there's just too much drag reducing the free movement of these wires. I think they need to be replaced with traditional pushrods, but the pre-installed plastic guides are a significant obstruction to that kind of installation. I think it will be necessary to cut into the fuselage at each former to clip the glued in plastic guides. I was hoping someone had a better process that I hadn't thought of. I really would prefer to leave the fuselage intact.

Greg

Chief - Yes, the same plywood stayed in, just punch out the factory stuff, insert the 1/4-20 brass insert's, get some epoxy in there and other area's of the fuselage. There will be no binding with the tube's, I thought the same thing, and addicted to the "old way". Put two servo's in the rear, instead of tearing the plane apart. If I was going to do that, cut the bottom of the fuse, section's between each former, go in and clip. You can see how I had to insert the elevator pushrod on Intruder #1, from the back, it is a little tight back there.

Each plane I recovered, the fuselage, tail, has been glassed.

Vince