Author Topic: Common build problem I have. (Read 4613 times)

Glenn (Gravitywell) Reach · « **on:** June 11, 2011, 12:24:44 PM »

When I am assembling a model, I zero the wing, stab and motor, then square everything. Then repeat till I'm happy. My trouble begins when I try to zero the flaps to the wing and stab. The flaps are generally in an elongated "V" shape that does not match the wing profile, nor the stab profile. What is the best way to zero it to the wing/stab? I don't have one of those fancy incedence meters unfortunately as they are simply too much money for me. Any suggestions are very much welcome.

W.D. Roland · « **Reply #1 on:** June 11, 2011, 01:08:24 PM »

'V' notch cut into one end of long piece of balsa. 3/4x 1/4 or something for the balsa stick.
Notch fits onto flap for entire chord of flap or most of it.
Notch must be symmetrical in the length c/l of balsa stick.

This stick slid onto flap should be parallel to stab or some reference(line) to fuselage c/l or something.
To double check flip stick over and split any difference.

Perry Rose · « **Reply #2 on:** June 11, 2011, 02:39:00 PM »

On profiles I drill a small hole through the fuselage on the chord line at the end of the flaps. On full fuselage planes I make a small dent in the fuselage side in the same location as the hole on the profiles. Make certain the bellcrank is neutral when leveling the flaps.

Paul Wood · « **Reply #3 on:** June 11, 2011, 06:59:51 PM »

Wrap a light weight rubber band around the wing and flap. You can eyeball the difference in the top and bottom displacement of the rubber band. Any misalignment is very apparent.

Paul

Brett Buck · « **Reply #4 on:** June 11, 2011, 07:11:58 PM »

Quote from: Glenn (Gravitywell) Reach on June 11, 2011, 12:24:44 PM

When I am assembling a model, I zero the wing, stab and motor, then square everything. Then repeat till I'm happy. My trouble begins when I try to zero the flaps to the wing and stab. The flaps are generally in an elongated "V" shape that does not match the wing profile, nor the stab profile. What is the best way to zero it to the wing/stab? I don't have one of those fancy incedence meters unfortunately as they are simply too much money for me. Any suggestions are very much welcome.

I just eyeball it by sighting from behind for the flaps, and from the side for the elevators. But mine are adjustable, so I know I can fix it later to some extent. If it's not adjustable, it really is, by bending the horns. If there is any doubt, make sure any error is on the side of having a little "down" elevator at neutral flap. Most of them end up that way anyway, after trimming.

Brett

Bill Allen · « **Reply #5 on:** June 11, 2011, 07:57:04 PM »

Glenn: I draw a centerline on a piece of mat board or on a piece of cardboard. I then trace the airfoil PLUS the flap silohette at the root as shown on the plans using the cardboard's center line to line up and match the centerline on plan's printed airfoil/flap drawing. When cut out of the cardboard/matboard the fit of the plan's silohette should be a close fit to the wing/flap with the centerline markings on the LE and the flap's TE matching those of the centerline on the cardboard piece. This is exactly what I did on my TWISTER project. Works perfect at almost NO cost. BILL ALLEN

Glenn (Gravitywell) Reach · « **Reply #6 on:** June 11, 2011, 11:03:21 PM »

WOW...what a bunch of great ideas! And to think....I never thought of one of them! LOL Thanks to everyone that has responded.

builditright · « **Reply #7 on:** June 12, 2011, 09:54:35 AM »

Maybe something like this might help

Jim Kraft · « **Reply #8 on:** June 12, 2011, 03:42:42 PM »

Thanks for that one Walter; That could be used for planes that have a fixed flap also, like the El diablo, and the All American. Those are the ones that need to be straight from the get go, and are pretty hard to get that way.

builditright · « **Reply #9 on:** June 12, 2011, 06:08:50 PM »

Quote from: Jim Kraft on June 12, 2011, 03:42:42 PM

Thanks for that one Walter; That could be used for planes that have a fixed flap also, like the El diablo, and the All American. Those are the ones that need to be straight from the get go, and are pretty hard to get that way.

I have been including them in my kits that have stationary flap type T.E.'s

Warren Wagner · « **Reply #10 on:** June 12, 2011, 07:43:24 PM »

Glenn,

If you have access to the drawing for the profile of the wing and flap, you can make a simple alignment
guide like this. In this case, the centering guide was made for the ARF Strega. It was made from
poster board type material, and it got the job done quite well. Just use care in drawing and cutting
out the airfoil pattern.

Cheers.

Warren Wagner

Warren Wagner · « **Reply #11 on:** June 12, 2011, 08:12:59 PM »

Glenn,

Another thought.....I don't know what stage your model is at, but here is a technique that I use for
perfect flap centering, but it has to be done early in the building stage.

In this photo, I wanted to keep the flap centered while setting up the pushrods. The jig is holding
the flap horn centered, based on visual alignment with the center line that is drawn on the side of the
fuselage (the centerline is something one should always do).

But, if you look closely, you'll see the head of a straight pin that was pushed through the fuselage
side, right on the centerline, and right where the trailing edge of the flap will be after its installation.
Simply push the pin through the fuselage side until it seats, and then cut off the length of the pin
that is inside the fuselage.

If you are real persnickety, you can remove the pin head before finishing and painting, or you can
leave it there, and always have a reference point for centering the flaps. Depending on how much
you love to sand, the head of the pin may be sanded off during that process.

Cheers,

Warren Wagner

Bill Little · « **Reply #12 on:** June 12, 2011, 09:15:35 PM »

I do draw a wing center line reference down the side of the fuselage so that I can wedge the flaps neutral when I go to set up the pushrods.

The methods shown here are great ideas!

Big Bear

Tim Wescott · « **Reply #13 on:** June 12, 2011, 09:58:42 PM »

Build an incidence meter. I've seen at least one build article for one, but I think it was years ago in FM. The principle is easy: make a bar with a fixed notch at one end and a sliding notch at the other, arranged so that the distance from the notches to the bar is equal no matter where the movable notch is slid. Then provide some means of measuring the deviation of the bar from level. For setting things up at 0-0, all you need is to know that the bar is level, which means that a cheap machinists level (or parts thereof) would be enough.

With enough scrounging, you could pick up a carpenter's level at a garage sale for a few bucks and extract it's spirit tube.

Steve Helmick · « **Reply #14 on:** June 14, 2011, 10:53:05 AM »

The KIM (Killer Incidence Meter) article was by Derek Moran, in Model Aviation...maybe 4 years ago?

If your plane has moveable flaps (and therefore a flap horn), the cutest method I've seen is to slide the appropriate size of brass, copper, or aluminum tubing from the LHS onto the legs of the flap horn and elevator horn to amplify the angular deviation and help determine adjustments needed before adding the flaps.

Steve

Glenn (Gravitywell) Reach · « **Reply #15 on:** June 14, 2011, 05:55:53 PM »

would anyone be able to send me a pdf or scan of that article? That sounds highly doable. All of these have been such good ideas....I always fumbled through by MKI eyeball.....and my vision is terrible!

Steve Helmick · « **Reply #16 on:** June 14, 2011, 11:16:57 PM »

Ask and ye shall receive! I hope to see you in August at "Perry Fire".

Steve

Bill Little · « **Reply #17 on:** June 15, 2011, 06:33:02 AM »

I have a good incidence meter, and use it. It works very well, but setting neutral on flaps can still be a challenge. I make sure everything is set before i seal up the fuselage and can still get to the pushrods.

Big Bear

Glenn (Gravitywell) Reach · « **Reply #18 on:** June 15, 2011, 05:39:23 PM »

Thank you very much Steve! I'm going to build me a couple of those....and make one of them mountable to the engine. Thanks, thanks, thanks.

ps....We better see you at Prairie Fire....heck, your one half of the flying contingent! LOL

Steve Helmick · « **Reply #19 on:** June 15, 2011, 08:05:06 PM »

Glenn...Rather than mounting an Incidence Meter to the engine, I'd suggest making it so's you can mount it to the engine bearers. I'm modifying a Robart IM to do that. Much less flex and thus more accuracy. It'll work on upright, inverted, or side-mounted installations.

"Perry Fire" costs at least $1000 for me, which makes it a problem. Free beer would cut that down quite a bit!

Steve

Glenn (Gravitywell) Reach · « **Reply #20 on:** June 15, 2011, 09:39:47 PM »

Thats an excellent idea Steve....I'll do just that. And as to the beer, well I don't drink, but I will certainly supply you with one or two. Whats your poison?

Steve Helmick · « **Reply #21 on:** June 15, 2011, 09:43:13 PM »

Any Canadian brew except Kokanee. That stuff is dry!

Steve

Glenn (Gravitywell) Reach · « **Reply #22 on:** June 15, 2011, 10:51:32 PM »

I'll see if I can get a concencous from my friends that like the brew and see whats best and wet! It'll be waiting for you!

john e. holliday · « **Reply #23 on:** June 16, 2011, 08:53:02 AM »

This last post reminds me of the old Swope Park Contests hosted by the Sky Devils of Kansas City MISSOURI. CD was Bill Wright. The guys from Colorado and the gang from Iowa would park next to each other. They were swapping their local beers. Seemed like more beer than planes.