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Old 01-16-2013, 10:56 PM   #276
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I think once a persone gets used to building planes they sorta do the picture thing
if they already have started doing things they think make the plane be more than the plan doe's ?
At least that's what it seems like on my end of the bench anyhow !
George
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Old 01-16-2013, 11:50 PM   #277
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You have to be careful with that. It's easy to try to second-guess the designer and make changes of your own, that more often than not make the plane worse, not better.

For example, we had a customer who thought that adding D-tube balsa sheeting between the leading edge and the spar would "improve" the plane. What he didn't realize is that for a number of reasons we had determined that the plane would be better without D-tube sheeting, and we had included special design features to make it unnecessary. In particular, we had measured the covering sag between the ribs, and made "corrections" to several places on each individual rib to lift the covering between the ribs up to the intended airfoil shape. When this customer added D-tube sheeting, the result was significantly distorted airfoil shapes all along the entire wing. The plane still flew well, but not as well as the stock airplane, and it also had some subtle handling quirks.

We have had a number of customers ask us about mods BEFORE actually doing them. In some cases they decided not to do the mods, in others they proceeded with them, but from a position of knowledge, and the results tended to come out better because of this.
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Old 01-17-2013, 02:13 AM   #278
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Default Second half wing build

I'm ready to build the second half of my wing. I'm taking my time and enjoying the kit. Thanks for everyone's imput and help. FishHawk.
ps I'm sure I'll have more questions. :
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Old 01-17-2013, 04:59 PM   #279
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Questions and ideas are the best way to redout the good from the bad and keeps things moving forward instead of back .
Got to go work on the G.L. for a while .
George
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Old 01-18-2013, 03:54 PM   #280
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Default Trailing Edge stock

The trailing edge stock notches on the right wing are way off. I have re cut the notches to the proper position. Yes, I used the shear webs for alignment, and I could have glued the rib in place with the rear portion out of alignment but I chose not too. FishHawk
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Old 01-18-2013, 06:02 PM   #281
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Did you measure the distance between the cuts manually? It's always been the plans that are off for me. The parts have been correct. I don't remember the exact distance, but each cut was the same distance apart on all pieces.


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Old 01-18-2013, 11:24 PM   #282
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FishHawk
It sounds strange that the parts are amiss in a kit plane guy , I have hade only two kits of any that were off as far as the parts were cut and one was from china -one from an old company that were on thier way out of buisness at time of production
and someone dumped a bunch unrelated parts in the box and shipped it to the LHS
and I hapened to be the lucky nut to buy it ?
George
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Old 01-19-2013, 04:00 AM   #283
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The rib notches are EXACTLY where they are supposed to be. DO NOT recut the trailing edge notches!

The problem is the plans. We have been fighting this since we first put the plane in production, and it absolutely refuses to go away.

The $10,000 digital printer at the company that prints our plans for us has a calibration problem. We have worked with them, done special training with their employees, given them a piece of trailing edge to use as a calibration standard, all to no avail. Things might get better for a little while, but with things like employee turnover, work schedules, etc., pretty soon the problem is back again.

And yes, we have looked for other places to get our plans printed; no luck so far.

The fact is that the vast majority of a print shop's customer base does not use their product as a template to build something from.

So, what you should do (as I have explained many times in many places) is make your ribs parallel to the lines on the plan, but let the trailing edge notches and the laser-cut shear webs determine their location.
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Old 01-19-2013, 01:02 PM   #284
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Default Too late

Well I'm too late !! I re -adujsted only a couple of ribs, so I'll probably be ok.
The only one that probably matters is the S rib. I hope this will work out ok.
There should be a note with the plans explaining this. You can do it with your printer at home and not have to reprint the plans. Just include a sheet with the problems . If I didn't have the internet the model would be wrong.
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Old 01-19-2013, 03:44 PM   #285
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Default Used shear webs to align ribs.

I used the shear webs to align my ribs and the aft portion of the ribs did not align with the notches of the trailing edge stock! The notches are off by .062.
When I built the left hand wing the notches were off slightly and it was not a problem like it is on the right hand wing. So, when I use the shear web to align the I re cut the notches to align with the shear web.
I will now check the shear web alignment with the notches and decide how to proceed.
I will try and take some photos to illustrate the problem.i am a retired aerospace machinist and used to working with accurate blueprints.
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Old 01-19-2013, 08:12 PM   #286
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FishHawk,

I'm not sure if I am seeing what you are so, here are some pictures from my latest progress. I have just finished up on the base right wing. It still needs finish sanding and the spoiler work, but that's done later after the wings are joined together. I have two closeups of the end of the wings with the other side exactly on the lines. As you can see the end of the wing ends up longer than the plans. I built to the parts and not the plans per Don's instructions. I used the plans as a reference just to keep the ribs straight. The ribs were spaced by using the training edge cuts and the shear webs.

I forgot to order the 3 piece wing kit, so I am creating my own based on the existing parts and some from my previous kit.

Steve


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Old 01-19-2013, 10:52 PM   #287
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FH, regardless of how they were printed, NO set of paper plans will EVER be perfectly accurate, simply because paper expands and contracts with humidity change, and not by the same amount that wood does, which itself changes by different amounts depending on whether it's with or across the grain (across the grain is quite a bit more than with the grain).

However, the main source of the problem is our printer. I had a discussion with Joe today on this subject. We're planning to get very hard-nosed with them and see if we can get them to clean up their act, as well as putting a note in the kit (something we should have done years ago but never seemed to get around to; I've seen similar notes in other companies' kits, so we're not alone on this problem), and looking for another company to print our plans for us.

On the 3-meter we have a different type of trailing edge that does not use notches, but we still have laser-cut shear webs, so the problem will still be there.

However, I doubt that any of that will completely eliminate the problem. The only real solution is what we have in our Roadkill Series kits, where the kit parts interlock and align themselves, and you don't need a set of plans to build on.
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Old 01-20-2013, 02:30 PM   #288
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Default Rib alignment

Steve, that's the alignment that I got on the left handed wing which wasn't a problem . The right handed wing is more out of alignment than that . I'll try to get some photos of the problem. Thanks FishHawk.
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Old 01-21-2013, 10:44 PM   #289
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Default Alignment photo

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Old 01-21-2013, 10:45 PM   #290
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Default This is what I am having trouble with.

As you can see the rib is out of alignment . The Shear web is not aligned with the notches of the trailing edge. FishHawk
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Old 01-21-2013, 10:53 PM   #291
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The Shear Web doesn't align with the trailing edge
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Old 01-21-2013, 11:03 PM   #292
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Of course it doesn't. It's basic trigonometry. The shear web is at a greater sweep angle than the trailing edge, therefore the spaces between the slots in the shear web have to be greater.

If the shear web slots and the notches in the trailing edge lined up perfectly when side-by side like in your photo, they would NOT line up when the wing was assembled!
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Old 01-22-2013, 12:50 AM   #293
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Default Why is the leading edge off.

Ok , then why are the leading edge slots off ? FishHawk
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Old 01-22-2013, 01:01 AM   #294
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Not sure what you're referring to, got a pic?
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Old 01-22-2013, 01:17 AM   #295
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Originally Posted by FishHawk View Post
Ok , then why are the leading edge slots off ? FishHawk
I am not understanding something. The leading edge is a dowel without any slots. One thing that I almost got mixed up were the shear webs. There are three on each 1/2 of wing. Each is different and you must get the right one in the right place.

I have not started on my left wing yet. I'll go and layout my pieces to get started and take some pictures. Maybe that would help??

Steve

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Old 01-22-2013, 01:32 AM   #296
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Default My mistake typo

The trailing edge notches not the leading edge. Explain the Tri for me . I'll take a try . Wouldn't the trailing edge notch be the point where the both legs of the triangle meet?
Here is the problem . If I use the shear web to align the ribs to the plan the rear section of the rib not in alignment with the notches of the trailing edge.
I can take a photo of that to show you what I mean if this is not clear.
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Old 01-22-2013, 01:46 AM   #297
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It might help everyone understand al of this if I add a little history.

Waayyyy back in about 1995, I designed and built the machine that notches the trailing edges, originally for the 1.5 meter HLG Chrysalis. It's very robust and consistent, has been doing its job since then with essentially zero maintenance. It cuts the longer piece for the HLG's inboard trailing edge, then a small gap, then the notches for the HLG's outboard trailing edge (which is shorter than the T.E. for the 2-meter).

For the 2-meter, we use the HLG's inboard trailing edges for the 2-meter's inboard and outboard panels.

The machine is extremely durable and maintenance free. However, getting the individual cutters in position and also adjusted to cut the correct notch width is extremely difficult and tedious. Once we had them set, we did not want to have to alter them. EVER.

With that in mind, all the rest of the wing is designed to match those trailing edges. There is a slight error in the trailing edge notching compared to the original nominal dimensions, so when we laid out the wing, we measured some actual trailing edges, and drew the rest of the parts to fit the actual dimensions of the notched trailing edge stock. That includes the shear webs.

The notched trailing edges do include notches for the A, B, J, K1, K2 and L ribs. However, these ribs get balsa sheeting over them, which requires removing enough material from their top and bottom edges to allow for the sheeting thickness. This causes the tail ends of those ribs to get shorter by about the same amount as the depth of the trailing edge notches. Those ribs come approximately to the trailing edge, but do not project into the notches. Their fore-and-aft location is set by where they sit on the lower main spar caps.

This is why Step 2 of the wing instructions does NOT use those ribs. They go in during Step 3, after the relationship between the spars and the trailing edge is already established, using other ribs that DO project into the trailing edge notches.
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Old 01-22-2013, 01:56 AM   #298
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There is an angle in the top view between the main spars and the trailing edges, they are NOT parallel to each other. The angle on the inboard panels is pretty small, and not a big factor, although it was included in the design effort. However, on the outboard panels, the angle between the main spars and the trailing edge is about 8.3 degrees. That is not inconsequential. The cosign of the angle is 0.9896, so 1/COS is 1.0105.

That means that the distances between the slots in the shear webs need to be about 1% greater than the corresponding distances between the slots in the trailing edge. Over a distance of 20", that accumulates to a total difference of almost a quarter of an inch.

Since the ribs intersect the shear webs at an angle, the width of the slots in the shear webs also has to be adjusted for this.

Note also, that since the trailing edges on the outboard panels are swept, but not at the same angle as the main spars, the relationship between them is not a right triangle, which further complicates the relationship.
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Old 01-22-2013, 02:00 AM   #299
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I just built the inboard half of one wing and had no trouble with alignment of the ribs or shear webs. That the plans are off in magnification a little threw me at first, but the various posts about that cleared things up. Except for a few fixable screw ups on my part (my first build in several years), everything seems good.

I will say, there are a lot of pieces to the wing and since I'm using tightbond, it's going really slowly.
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Old 01-22-2013, 02:16 AM   #300
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Default Thank you again

Don, thanks for clearing this up. Your explaination helps me understand the difficulities that a designer has in making a functional model.
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