UStik

As to the TBX-1 wing, there's no picture of a plan view, but the small ribs have long tabs and the big ribs have small tabs. The upper part in the third picture could be a brace. Looks all like anhedral wing (opposite of dihedral) built upside down. The airfoil seems very conventional, likely a NACA 4-digit series with their blunt leading edge. There's no washout (neither washin) since all ribs on their tabs would be parallel to the building board.

Where's the plan view?

RFJ

Looking at the rib drawings, Tom is building the wing upside down using a conventional cambered wing section at root and tip and probably with the rib center lines a constant distance from the bench. Hard to tell without measuring but it may be slightly thicker percentage wise at the tip - another trick sometimes used to prevent "tip stalling" The two "egg crate" spars are also drawn upside down. Judging by the join angle of the spars, this wing will have anhedral.

Sooooo... Yes.

Ray

kingaltair

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I was kidding with you about the camera distorting the image. I've been into photography for over 25 years, (though not as fanatical as some are). I know very little about EXIF values; I guess I'm just not that interested in that aspect of it.

Both of Chuck's pictures look about the same to me.

Duane

kingaltair

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Patience...patience mein freund. To quote the "Wicked Witch of the West" in the movie The Wizard of Oz "...All in GOOD TIME my little UStik...all in GOOD TIME..."

I guess I might be able to answer my question by looking at the side view, but I don't have it in front of me.

UStik

We're both kidding, and it's these darn digital cameras that we have all this fuss. EXIF is the format of the data stored in each picture file, and the program (PTLens) looks there for the focal length used for the shot. It has distortion parameters for several cameras/lenses and can undistort pictures automagically.

Save the two T2 pictures to harddisk and view them alternating with the Windows preview program - you'll see the difference.

kingaltair

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Everyone;

I looked at the side view of the TBX-1 plan, and sure enough, the wing is semi-symmetrical with the thickest portion on top...the wing is built upside down. I forgot about side views when I was concerned earlier. I am hoping that with some discussion we will be able to fully understand the thought process behind this plane. I guess that means the wing was designed with anhedral.

Still would like to know the reason for this, and the flight characteristics that were desired.

Duane

pimmnz

Briefly, and in laymans terms, if the wing is on top of the fuselage it (the airplane) will roll with rudder application in the direction of the yaw. My guess is that in order to reduce this secondary effect Tom has added a bit of anhedral to try to cancel the effect, ie the anhedral tends to roll the airplane in opposition to the applied yaw. the total effect he was aiming for is that the model will yaw without any appreciable roll.
Evan.

Michaelj2k

What is the possibility that the tabs shown on each rib are actually a long support that is shaped to match the airfoil and attached to the building board and not part of the rib? When the wing and stab are under construction, the support which would be as long as the wing panel, is used to pin the rib down to hold it in place while the spars and other associated parts are being assembled. If you look at a picture of supports for ships in drydock, you will see what I mean. The supports are sized to match the shape of the ship's hull. http://en.wikipedia.org/wiki/Drydock

Another thing I see is the support is extended into the sheeted area of the ribs. Were the balsa skins pinned the building board supports then ribs, spars and associated parts added? This method would certainly insure proper wing alingment and automatically build in the required washout and anhedral.

I don't know of anyone using a technique like this.

kingaltair

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The way I see it, the tabs on each rib, and the extensions of both the main and minor spars are in contact with the building table as they come together in "eggcrate" fashion. Once together, the bottom sheeting is applied to hold everything together, then the wing halves are flipped over and the tabs removed. It is possible that the anhedral is already figured into the support tabs, (we'll have to see from the plan how it comes together), so that only the root ribs and spars require some sanding where they join. The bottom sheeting then holds everything in place while the top sheeting is applied.

One thing we know to do is to cut all the ribs and spars with the tabs as shown, and alignment should be correct. I assume Tom did all that figuring for us in the plan, so that only assembly is required. That's the hope at least.

I'll start working on the photos I took the other day to get them ready to put in the thread.

Duane

Free Bird

WEDJ did something similar when he built his Perigee last year. Without the supports, and because the way the grain of the sheeting ran, the wing would have had the dreaded wash-in that gave the Perigee it's snapping reputation. Maybe this was a "lesson learned" from past experience?

But if there are tabs on the ribs AND spars, a jig for each rib shouldn't be needed, only a flat building surface.

FB

kingaltair

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In my quoted post, I didn't mean to imply that anything but a flat building surface would be needed. It would be nice if Tom designed the support tabs on the spars and ribs so the anhedral component of the wing was already accounted for by the lengths of the support tabs. That way the wing could be built in one piece. The wing plan has an original and a reverse, and does state that the two are supposed to be cut along a certain line and joined to build the wing. I haven't gotten that far in the description of the plan.

Duane

Free Bird

Not to get off track with the TBX-1, I thought I'd post a few pics of my Perigee restoration. I got the model last November from you know where for a good price. My intent from the start was to strip it, glass it and paint as close as possible as Tom's model in the AMA museum. Thanks to Duane (kingaltair) for providing some pics and memories of Tom's model to use as guidance. First some before pics. As you can see, it was covered in film and not to well at that.

FB

Free Bird

Now here's a few after pics. It's glassed with 3/4 oz. cloth and WBPU, so far it has picked up very little weight. The wing is ready for clearcoat and the fuselage is ready for the trim scheme. All of the control surfaces will be dark blue on the underside as will the stab. As you can see, the bottom of the right elevator is already dark blue and the top of the left elevator is light blue. The ailerons are ready for the same treatment. So far I'm please with the transformation, it's starting to look like a Perigee! The paint isn't perfect, but then I do want it to look a little aged. If all goes well, it'll be ready to fly in 2 or 3 weeks. At least that's the goal so I can fly it at the Octoberfest. I'll post more pics when it's completed.

FB

kingaltair

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FB-

Way to go......it's a pretty paint scheme isn't it?

Thought I'd post three pictures to give you a feel for how the original plans looked by spreading them out on a table, (on my deck for extra light). Tom worked with relatively narrow, but sometimes long drawings that looked very much like scrolls when rolled up. These rolls were all located in a cabinet in his drawing room.

The condition of the fuselage sheets was readable, but dark and faded as you might expect from something this old. The fuselage and rib template sheets were darkest, and suffered the most in the copying process. As you can see, the wing sheets were in good shape...I wish they all looked like the wing sheets.

About the wing, (sheet 3, I think), there was another duplicate but reversed, (ie backward) sheet included, so both sides of the wing could be built at the same time. There is a note on the plan that tells you to cut and join the plan on "this line."

Not too much time to work on the plan pictures today.

Duane

Free Bird

Certainly is and it has good contrast between top and bottom. The more paint I get on it, the better I like the trim scheme.


To build both panels of the wing at the same time, one would need a pretty large building board.

FB

kingaltair

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I just has a 4'X8' table built for me like Kevin Clark's, (see the King Altair build). It's topped by a metal sheet so magnets can be used to hold parts in place. This was built with the Simla in mind, but it should make any building easier. My wife was getting tired of me building wings on the dining room table.

Duane

pimmnz

Found this gem while relaxing over a coffee...seems RCM&E thinks that Tom tried propo after all...
Evan.

kingaltair

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Who knows, but I think we have discovered from research on the Ed Kazmirski's Taurus thread that you can't believe everything you see in print just because it's there. I know for certain that Tom at least experimented with proportional radios because I remember seeing him personally with Ed Kazmirski flying the Taurus-2 for part of a flight. He may have flown other people's planes, and experimented, but I very much doubt he "flew proportional" for two years, then returned to reeds. Every time I saw him during the period where he was supposedly flying proportional he was using Bramco reeds.

That would be a good question for Mrs Brett. I'll try e-mailing her for some answers to our questions.

Duane

Free Bird

A few posts back there was speculation whether or not the TBX-1 has anhedral, while I do not know the answer, has anybody noticed that our premier USAF heavy lifter, the C-17 does have anhedral. Was Tom ahead of his time?

FB

kingaltair

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Yes....... I'd have to say that the TBX looks more like that cargo plane than anything else, (as opposed to a fighter like Brook's Crusader). I don't know when these types of cargo planes were designed, but if it was before 1965, it might have influenced the design.

One of the questions I'd love to ask Tom if here were here is exactly what plane was he patterning the TBX after, and why did he choose this design, (that looks a little like a cargo plane), instead of something that would be more likely to fly the pattern well. I hope that some day I'll be pleasantly surprised when I try to fly the pattern of maneuvers with it, but at first glance, it doesn't LOOK like it is the best design in the world for pattern flying.

That said, it is still a `tre cool design. My favorite feature is the wing sweep, with greater sweep on the L.E. with progressivly less sweep as you go toward the T.E. One note that Tom puts on the wing plan, (that I'll post soon), is that he figures the degree of sweep at three different points from front to back. I belive the figures are 33 degrees, 22-degrees, and 18-degrees on the T.E.

AndyKunz

That sure looks like the LE and TE are straight in those photos. Where do you get 3 different angles?

Andy

kingaltair

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From the plans. I was at work when I first talked about this. There are what I take to be four angles corresponding to the leading and trailing edges, and the angles formed by the main and minor spars.

Duane

pimmnz

He means the angle between the the spars and ribs is different between the front and back of the wing due to the taper, not that the L/E has 4 different sweep angles.
Evan.

kingaltair

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I am happy to report that Helen has been reading this thread and all your comments, (so we need to watch what we say). She has also answered a lot of our questions. Whenever possible I'd like to copy her own reply to me by e-mail which I think proves to be much more interesting reading. The scrapbook she refers to was a huge scrapbook that documented Tom's career in R/C and later, building a full-sized plane at home. It must be at least 3 inches think. I feel honored that she thinks enough of this thread to want to print it out, and include our little forum in her book........

Duane, I have been reading the thread since 4:30 (ed...it was almost 7PM when she sent this e-mail), and just printed it for the scrapbook..Very interesting. I feel I'm in the basement going through the process all over again. I truly enjoyed those days, partly because Tom was patiently waiting for me to be ready to take up full size flying. I'd go down there and keep him company lots of times, knitting or reading while he whistled away at the drawing board or cutting and assembling. He enjoyed every part of the process. The sparkle was taken out of my life when he passed away, for sure. This is letting me relive that part of our life again.

Dee Bee was the (proportional) system Don Brown flew in Europe on the FAI team. You could find it in the article from the 61 Nats, I think He was working on the newer version and got Tom interested, hence Cirrus. The outfit was sent back several times for malfunction and Tom lost interest in it......He preferred reeds. Maybe because he played the piano, strummed a uke and guitar.

The original Nimbus, the one flown at the 61 Nats was white with shocking pink silkspan on the wing. When we got home from the Nats, maybe late July or early August, Nimbus met its demise and he hurried to build a new wing and repair the fuselage. That is why the Nimbus II looked different, white with marroon trim.

So Tom did try proportional out, but the system was a very early design, and it was unreliable. Under the circumstances, it's not to see why he went back to reeds.

Thanks Helen

More to come............

Free Bird

Very nice Duane! I'm happy that Mrs. B. has been in touch AND following the thread! That scrapbook must be a treasure of info and pictures from the glory days.

Also, I'd like to thank Mrs. B. for the interest in the thread, allowing Duane to visit and take those wonderful pictures, and the colors of the Nimbus II! I for one truly appreciate it!

FB