Thanks to Bob Noll’s videos and the help of Lance Van Nostrand I’ve learned some pretty good techniques for aligning stabs and wings to make sure everything is perfectly straight.

However, the one thing that always drives me crazy is getting the fuse perfectly perpendicular to the stab/wing. What makes this so hard for me is that normally the rudder post (or rudder if already mounted) has a taper. This means when I set my triangle behind the rudder to see if it’s straight it ends up close at the top and far away at the bottom (or visa versa). To try and make sure it’s square I step back and try to eyeball it but this ends up driving me bonkers, one eye open, two eyes open move to the left move to the right, all of this changes the way it looks. OK, now you know how anal I am .

Anyways, the other day I saw a picture of the rear of a plane here on RCU (Mike East’s to be exact), and a lightbulb went on! If you have a picture from exactly behind the plane you can use photo editing software to display a grid and tell very precisely if the wing and/or stab are perpendicular to the rudder. For that matter, the table doesn’t even have to be level.

Obviously this isn’t a replacement for a triangle and eyeballs, but I think it’s a useful tool.

Here’s an example of the Brio I’m building:

One thing that I didn't mention that's important is that, unlike the picture I posted, when you have the full resolution version of the picture you can zoom into extreme detail and line everything up in bigger than life detail.

Also, your picture won't initially be exactly straight so you’ll need to use the rotation abilities of your photo software to rotate until everything’s aligned correctly with the grid lines.

Keith B

So, was mine straight???

Also, how do you like the Brio compared to what you know about the Genesis? I gave it a long hard look and went with what was familiar to me..

Good. Just a little bit closer to using a transit type feature. FYI, using a transit is the most accurate method I have used yet for alignment. It allows real time adjustment. It also literally measures angular differences easily so the wing and stab relative angles (decalage?) may be adjusted precisely. It looks like you like to tinker, so this suggestion could be useful to you.
rgds,
MattK

GREAT idea Keith!!!

Matt, what is this transit method? Could you explain it?

Good idea Keith,

I like your ingenuity.

Being a follower of the "List", I have always enjoyed your, and others, insights to difficulties we all have in building and flying Pattern planes. I don't build anything, except ARF's, however it's surprising how many things carry over from kits to ARF construction.

Thanks for the idea,

Ken Thompson

Thanks for that information. It helps a lot!!

What about getting the horizontal stab square with the wing? The 'string' method that some kits/arfs use or measuring from the wing tip to the stab tip is a bit off. These methods seem to be a bit lacking for some reason... there must be a better way. When I do it, I end up 1/8 inch either way and never exact.

For example, the Excelleron 90 I am building. When I was done, the covering on the horizontal stab was not symmetrical so it looked crooked so I remeasured and still it did not look straight. But it seemed to measure out correctly.

I know that the covering is probably not straight or exact, but I was hoping that it would be a guide or something pretty close.

Any hints on that?

DS.

Hello CG,
I'm not sure I understand well what you say, but... here is my reply.

The wing tip - stab tip measurement is a good one and necessary to align the wing and stab together. Previously the wing must have been aligned with the fuse in the classic way: mount the wing in place and the measure LE from root to tip left wing and right wing, then the same for TE. Then, measure distance between wing tip and fuselage tail (i.e. where you hinge your rudder).
All these measures must be equals or must be "equalized" as close as possible (1mm tolerance is ok...). The the stab: make the above measurements and the stab is automaticalli aligned with wing and fuselage. It remains to check stab against wing for perfect aligment when seen from behind: here eye is really a precise tool! Also the Keith idea helps a lot to have a really fine tuning!

If you are still in doubt, CG take a look at this thread, where can be seen a professional builder (Mark from ZNLine!!!) making one of their planes. When I discovered it I did not sleep the night!!! All building stages are explained with pictures, wing and stab alignment included.

Here's the link:

http://www.rcuniverse.com/forum/m_53.../tm.htm#534573

Good reading!

Got it! Thanks. That is a long thread and I will read it part by part. Good stuff!

Thanks again.

DS.

Kieth and others,

I have used the Bob Noll methods and variations of it. Make your rudder post insert and have it dry fitted in the fuse. Hold in place with masking tape Use a Great Planes centering marker and make a scribe mark in the post insert. This is a great tool for marking aileron and elevator hing lines on tapering sufaces aslo.

Then use the Bob Noll method of squaring up the fuse to the table. Center line on table and a perpendicular line to that at the stab line area. Use a large square to get the fuse perpedicular to the table by lining it up on the scribe mark in the rudder post insert and the perpendicular line on the table. Doesnt matter if there is rake in the rudder post if the square is on the table lines. Make sure the fuse is held firmly to the table with bungy's and blocks. Now you are ready to set the stab. Remove the rudder post insert and set the stab in position, shimming to get it square in the fuse You now use the table as reference points to setting the stab. A pair of adjustable holders to keep the stab in place are needed here. Using a hiegth gage to reference the leading and trailing edge. Then use the Bob Noll measuring rods to set the stab square to the fuse.

Better yet.... just build one of Buddy Bramers laser alignment tables. (Like I even have time to build airplanes heh! heh!)

Some people set the wing first. I find setting the stab first easier to keep things square. Then set the wing paralell to the stab. It is easier to sight from the back to align the stab and wing. This is all info I have acumalated from others and some have different and varing methods depending on thier shop setup.

I will take some photos of this method and post them here along with some photo's of my home made tools that most anyone can make with general shop tools.

Wayne Galligan

I agree with Wayne and normally set the stab first.

The alignment process can be really difficult to describe. If you want a really good course on how to align a plane I highly recommend Bob Noll's video "Perfect Airframe Alignment". Even for those that already know how to go about aligning a plane this video is really helpful. Bob also sells some useful alignment gadgets if you don't want to build your own. In the photo I posted you can see one holding the left wing in place.

Keith Black

Stek, a Transit is a measurement device used mostly by architects and civil engineers. Both build things, buildings and roads respectively. Using a transit is not as difficult a skill to master. You can get one on eBAY for less that 100 bucks for a basic model.

MattK

Very creative. You get an A+++

Did you cut of the rudder?


Eric.

Dear CGRetired,
You might want to be sure you have the stab centered on the fuse. I had the exact optical illusion once and it drove me nuts too. Then I found my stab was placed about 1/4" off center. When you get the wing-stab distances equal, the stab is crooked.
--Lance

Guys,


is this perfect airframe alignment video available somewhere?

Thank you!

Yes the video is available:

Absolute-Accuracy Series
Perfect Airframe Alignment with Bob Noll
Produced by Robin's View Productions
PO BOX 68, Stockertown, PA 18083
Phone: 610-746-0160

He also has three other tapes available, which can be bought separately or as a bundle. Perfect Engine Mounting, Prefect Removable/Adjustable Stab and Perfect Foam Wing Construction.

I have all four and they are extremely informative.

Keith B

Eric, I'm not sure what your question about the rudder was.

Keith B

A lot of Brio buiders, (regular and master builders!) just cut off the rudder and threw them away. then they made new, much lighter, and mylar hinged versions.

Eric.

Eric, I wasn't aware of that. I did make a new rudder for my Impact, but I've heard nothing about people replacing the Brio rudder. For that matter I've heard very little about Brio building at all!

Did you get this info via a forum or elsewhere? I'd love to get access to any and all info available. I've seen the thread where you listed your Brio's weights, but that thread doesn't really get into detail on the building (problems and solutions). Outside of that I've not seen any other threads on the Brio.

I'm considering starting one myself.

Thanks,
Keith B

Hi Lance, thanks for the reply.. sorry it took so long to respond.

I already epoxied the stab to the fuse thinking it was square, which it does look. Two different people looked at it and they came to the same conclusion as I did that perhaps the covering was not on exactly straight so it looks crooked by the covering but is in fact square with the wing and fuse. All will show up I'm sure when I fly it in a couple weeks.

DS.