Scratch building wing ribs

[Twmaster]

I have a model I have wanted to build for a long time. The problem is that it is available in plan form only. I can cut simple stuff like fuse formers and such but making 40 identical wing ribs is going to be about impossible for me and I really want to learn how to build from scratch.

Anybody? Bueller?

[RCKen]

Twmaster,
If you have a scroll saw or band saw, cutting identical parts like that is fairly easy. Start with the correct thickness of wood for each part. Then stack as many layers of wood that will fit through the saw at one time. Make copies of the part from your plans, use a scanner or copy machine, and apply it to the top piece of wood. 3M 77 adhesive spray is great for attaching the plan, you can even use a light coat of adhesive spray between layers of wood to keep them together. Now cut the shape of the part out of the stack of wood. Now you have many identical parts. This will really cut down the amount of parts you need to cut.

Hope this helps

Ken

[50+AirYears]

Trace the wing rib(s) onto some 1/8" basswod or ply, cut out and and to finished size, and cut the spar openings to approximate size. Drill a couple small holes for pins to hold the pattern in place on the balsa wood. Cut around the pattern with a sharp #11 blade. Might take a bit of time if you have a lot of ribs. Stack sand and trim the spar openings to fit.

[Turbojoe]

My scratch builds haven't required 40 ribs so I just cut them a couple at a time. I use counter top laminate for templates. I use a glue stick to apply the cutout from the plan. Then I cut the template out on the band saw or scroll saw. The template will last forever. I can cut right up against it for perfect parts every time. I usually don't even have to sand afterward. Having the bullet proof templates means I can cut out a "kit" just about any time I want.

Here's a shot of just a few of the ones I made for my Eastwind Models Gemini twin.


Joe

[50+AirYears]

I've been thinking of making up a set of ribs for a plane I got out of a book. A 1958 Flying Models. N3N biplane. That was the Stearman PT-17 as built by the Naval Aircraft Factory. So old, the plans show a Morton M-5 radial engine and mention a Bonner Varicomp single channel escapement. Problem is, they want 88 basic ribs and a number of specials. But, the magazine printed the plans at 1/4 size and had full size patterns.

[Twmaster]

Thanks for the tips fellows! I might just start the project I had in mind for this sometime soon.

I have an old Wards tabletop jigsaw too! :D

[beaubird]

I recently completed the Hobby Lobby Miss Stik (GREAT airplane, by the way), and noticed that it doesn't use ribs at all. You just bend balsa over the spar and attach it to the leading edge (dowel, in this case), and to the trailing edge. Seeking to avoid cutting ribs, I have designed a sort of electric Sweet Stik (42 in wingspan) and used the same technique, though in this case I developed a semisymetical wing, rather than flat bottomed (as Miss Stik). Seems to work just fine, though I haven't flown this new design yet. Just thought you might like to hear yet another way to avoid cutting all those ribs. I can forward a pic if anyone is interested.
beaubird

[Twmaster]

Thanks for the tip Beaubird. The Miss Stik is a terrific plane and Tom Hunt's (the designer) way of building ribless wings is pretty cool too. Sadly the plane I have in mind to build won't likely lend it's self to that sort of construction.

I need to learn how to do wing ribs from scratch sooner or later so I may as well get busy! :)

[beaubird]

Hi Mike - Yeah, I know the ribless design probably wouldn't work for some projects. I probably have cut out a thousand ribs, give or take, and the previous responses pretty well summarize the various ways I have tried it - had nothing new to add to that. Well - makes a good winter project, anyway.
Beaubird

[starcad]

I'll add something. Why not just draw the rib in CAD and then upload it to a laser cutter. Takes a few days but the results are anything short of fantastic.

[Twmaster]

I'll add something. Why not just draw the rib in CAD and then upload it to a laser cutter. Takes a few days but the results are anything short of fantastic.

Kinda defeats the idea of scratch building a model doesn't it?

[50+AirYears]

Great, if you have CAD available.

For a real load of fun with rib building, try the wing for the Goldberg Valkerie. A 1938 FF design, frequently duplicated for RC ot competition. Something like a 10' span, 1200 or 1400 sq in area, elliptical winged streamlined beauty. Something like 38 or 48 individual pairs of underchambered ribs built up from sticks on jigs, just like the ribs on the older wood full sized airplanes. Something like 12 to 15 individual pieces of wood on each rib. Designed WAY before CA glue. And the locations of certain pieces determine whether or not the ribs line up on the built-up spar assemblies.
People have admitted to taking a short cut and just cutting the ribs out of sheet balsa, but that seems like cheating, doesn't it?

[Twmaster]

Holy banana goo!

That would take a slow building schmoe like me a year to just cut ribs!

[50+AirYears]

First article I saw about building one, 3 people took over a month just to build the wing. Apparently, the spars are built the same way as the ribs. A masochist's delight. But a beautiful plane.

[Twmaster]

Masochist. That's an apt label! :)

I love the looks of many of the old timer models. Those graceful polyhedral wings and sexy eliptical outter wing panels are the bee's knees IMHO. Must build one someday.

[Commander_Drake]

I don't have a band saw. I cut all my ribs by with an xacto using See-Temp template material. If they are all the same size you can pin them all together, put some short temporary square stock in the notches and sand the whole group as a block. Then they are all identical. I have even done this with gently tapered wings.

[eflight-ray]

There is always the foam core alternative to balsa ribs. I must admit that I prefer chopping balsa myself, but I have built a few models now using white polystyrene foam, (and blue foam).
Have even hot wired a basic core and then sanded a Spitfire wing out of it. Well I tend to be lazy, and the thought of trying to create all those different shaped balsa ribs was too much.
Foam cores also do not have to be clad in balsa etc, mine have been covered in various ways including, brown paper and pva, glass cloth and epoxy, glass cloth and acylic varnish, (my current method, can't stand the epoxy fumes).
They may not be quite as light as an open balsa build, but worth considering.

[Twmaster]

Thanks for the input about foam cores. The model under consideration for built does not lend it's self to foam wings as it in 1:1 scale is a fabric covered homebuilt. To me it seems making the wings out of foam would be more work than balsa.

[eflight-ray]

?? Your building a 1:1 scale, (full size?), fabric covered homebuilt and your using balsa?.
I assume your still talking about an R/C model, but a BIG one. If I'm still right, then I would build big ribs from strip wood, something like 1/4 square spruce, (not balsa), in a jig as per some of the homebuilts, and some of the very large models.
Sounds like one hell of a project, good luck.

[Jan Jurek]

Hi
Just to dig into the "DARK AGES" Anybody have some experiencence with Dinajet pulse engine? I have just received as a gift brand new engine with set of spark plugs and igniter coil, but no start at all. Keeping all the rules of the game like level of fuel (80 Oct. gasoline)1/2 inch below the center line of the engine etc. and nothing. (even leaning the nozzel with a small cooper 0.1 wires (3 for the starters) to lean it out.Iam in Mexico City 8700 feet. I remeber flying here with old Jestar-8 and having some bad hot starts on the aeroplane back than in Mx. City. Any chance it can be the reason why this beast dont want to start???? Sure could use some help on this one.

Jan Jurek

[50+AirYears]

Dynajet engines were fun to start. They were very sensitive to fuel level for one thing. And you should have some hearing protection as well. They are LOUD!
Are you using a bicycle pump to provide the air pulses to start? You may get some great excersize.
If you get onto the AMA (Academy of Model Aeronautics) website (www.modelaircraft.org (http://www.modelaircraft.org)), and search for the North Coast Control Liners (NCCL)club, from Cleveland, Ohio in the chartered club site links for the State of Ohio, l think you will find a contact who can put you in touch with a local gentleman who flies Dynajet speed control line planes in competition. He has a starting system on a wagon that uses a pair of SCUBA tanks for an air supply.

[Kapn Kaos]

I recently built a kit with an eliptical wing that was missing most of the ribs. I cut rectangular blanks from sheet stock, trimmed them to length and notched them to fit on the spars. Then it was an easy task to use a block sander to get the right rib profiles. I used a lot of "TLAR" technology.......That looks about right!

[nakelp86]

There is always the foam core alternative to balsa ribs. I must admit that I prefer chopping balsa myself, but I have built a few models now using white polystyrene foam, (and blue foam).
Have even hot wired a basic core and then sanded a Spitfire wing out of it. Well I tend to be lazy, and the thought of trying to create all those different shaped balsa ribs was too much.
Foam cores also do not have to be clad in balsa etc, mine have been covered in various ways including, brown paper and pva, glass cloth and epoxy, glass cloth and acylic varnish, (my current method, can't stand the epoxy fumes).
They may not be quite as light as an open balsa build, but worth considering.
Want to cut some blue foam wings (60" wing of 2 30" pannels).
looking for some inexpensive and reliable way to make a foam cutter and the templates. Any info greatly appreciated :-))

[Bob E.]

Go to Model Airplane News------- "How to build a wing jig".

SCRATCH BUILDERS NEED THIS HANDY TOOL!!!!

Good Luck

Bob Ewing

[ablaker2]

Hi. Blake here. First I would like to know what tools you have to work with. That will determine the starting point for scratch building ribs or anythings else.
From a tool list I can give you some pointers that will help make it a little easier. But I warn you...a good job requires a lot of patience and tenacity.
With out modern tooling it is one of the hardest jobs of building to cut identical parts.
Let me know if I can help.
Blake

[Twmaster]

I have a very old scroll saw (or perhaps it is a large jig saw) plenty of clamps, power sanders and such.

[Bob E.]

Go to www.modelairplanenews.com (http://www.modelairplanenews.com) click on SITE FEATURES, click on ARTICLES, Click on HOW TO ARTICLES, click on BUILD A RIB JIG.

Not much needed to build jig, and only Exacto knife to cut ribs. Works well.

A 40 rib stack is hard to keep perfectly plumb under the saw. If not perfectly held you will not be happy with the results.

Cut my first ribs in 1942. Just go slow and remember the job is to please you, NO ONE ELSE!!

Bob E.

[ablaker2]

It is always nice to get the best economy from a sheet of Balsa but it is not usualy the best way to get a number of ribs cut correctly.
I would begin by cutting rectangles a littlle oversize then the ribs. Pin these rectangles on top of each other with as many as will bit under the jig saw foot, include a 1/8 pattern Using a block sander laid flat on the table. square the top and bottom edges of the pile. If this is an airplane that you will make more than one of,,,I would suggest that you make a single rib pattern from 1/8 inch tempered masonite. You must use great care making the pattern for it will determine how well the ribs turn out.
Pin the ribs to the pattern and using an xacto saw cut the slots for the spars first while the parts are still square (there are some small jigs you can make that will make this easier)
Once your slots are cut, cut a rough out line of through the stack being careful not to touch the pattern
Once your stack is cut. Fabricate a Drill press or drill press holder to hold a hand drill Purchase or make a sanding drum that you can add a 1/8 metal circle to. This should go on the bottom of the sanding drum
Set stack up on the drill press table and use the metal wheel on the bottom of the drum to act as a guide let the 1/8 pattern run against the metal wheel. the result will be almost perfect sanded ribs ready to use, this is only a good idea when making multiple ribs of the same size.
For a tapered wing cut you pattern from the heavy card stock and stack a set of 2 oor 4 ribs (a pattern is needed for each different rib)
then carefully rough cut each set and sand the sets together. I would still make rectangles first and cut my slots for the spars before shaping.

Blake
ablaker2@sbcglobal.net

[gfdengine204]

Having never cut ribs yet, I may be way off base, but.....

I understand the need to make sure they stay perfectly aligned while cutting with a saw.....what it you used the rectangle technique (having a stack of rectangles slightly larger than the rib), and drilling 2 or 3 (or however many seem appropriate) holes in the ribs for dowel rods. Place the dowels in the ribs to hold them together, then cut the pattern. After you are done, you remove the dowel, and also have some vent holes for when you are covering with heat-shrink covering.

Just a thought......

[pd1]

Hi Kev, Your method will work, but you will be doing a lot of extra work.

Here's a simpler way.

Tapered wing. draw the top view and space the ribs.
Number the ribs and measure the lengths. You can size the ribs to fit these measurements with a lot of photoshop type programs.

Print the ribs full size.
Pin the rib drawings over two sheets of balsa.
Rough cut the balsa ribs and sand to final shape with a block and 180 grit paper.

First picture pinning the rib patterns to the balsa.
Second metal jig I made for cutting spars.
Third cutting spar slots with razor saw.
Fourth rib with spar cutout.
Fifth out of sequence
Six spar fit.
Seven and eight, rib layout, no glue

I can make a set of ribs for a wing in less than 1 hour this way.

If the wing is constant chord, stack about 6 to 8 ribs and cut and sand.
Here's some pictures of cutting ribs.

[Papaw14]

Want to cut some blue foam wings (60" wing of 2 30" pannels).
looking for some inexpensive and reliable way to make a foam cutter and the templates. Any info greatly appreciated

I built several hot wire cutters out of a 12 volt battery charger and a lamp brightness control. I used the dimmer switch on the 110 volt of the charger and regulate the temperature with it. The dimmer has never burned out and I also use just about any small bright wire.