Dope free build

My next project I fear is over my head complicated....a big Shoestring. Looks a bit too intimidating to me...and needs lots of unincluded extras I have no way of procuring! wrote:

What size is it i have the 42" model w/a Enya .29 that may or may not bee broken in , but it needs repair from yrs. of ... Built when i was 17-18 YO

Ya..it's the 42"er Eric.....

There's nothing complicated about a Shoestring. I don't know why your suggesting that it's any different then the model you just built. If anything, it would be easier. If it's a Goldberg kit, they practically fall together. A Brodak version is bit more complicated because for some reason Miller who draws the CAD has to fix everything until it's broke.

Ya its a Brodak!....and I don't have a wing jig !
..

You don't need a wing jig. I built mine right on my bench top. The wing is the easy part. The bellcrank is a pain in the rear and if I did another I would've chucked it. It's not that a suspended bellcrank isn't good, it's the fact that my huge hands and fingers don't fit into the little area. I had my daughter install it.

Besides, a wing jig can be built in a blink.

2 each 1"x2"x48" oak jig base
1"x2"x(roughly) 5.5" oak rib stations, as many as you have ribs.

1/4"x5" machine screw and nut (wing nuts are convenient, but not needed) for every four ribs, starting and ending outside of the first and last rib.

Drill press the jig base between your rib stations, such that you trap four rib stations between the machine screws.

Clamp the rib stations between the jig base plates.

Check out the Guillow's Typhoon with LJB wing. The wing was built on a cheesy jig as described. Once built, the wing can stay on the jig long enough to attach the fuselage and proof the incidences of wing/tail/engine thrust line pretty easily.

The best way is to take the two spars which I believe are bass and lay them on the print and mark each rib location. Mark the spars inboard, outboard, top and bottom. Pin the bottom spar to the plan. Stack the ribs on the bottom spar in the proper order and on the marks you just made. Apply the top spar to hold everything together insuring that your on all your register marks. Brodak provides what they call a building stick which is approx 3/8"x1/2". Brodak provides points I believe on the print to apply this stick which the tail ends of the ribs set onto. Rather than rely on the points they offer. Insure that the spars are square vertically to the table at the root rib and the tib rib which is done by sliding this stick fore and aft wherever is needed to insure the spars are square. This stick isn't going to be square to the root rib, it's going to be parallel to the trailing edge which is angled.


               Most importantly, don't skip the shear webbing on the spars. The print shows cross bridging which they only show going out a few bays from the center. 1/16" vertical grain sheeting from one spar to the other is just fine. Do this to the trailing edge as well. Otherwise you will have a very weak flexible wing that's also susceptible to bowing and warping.

Know what engine your going to use prior to gluing the doublers on. The kit is designed around the Brodak .25 and other engines will require modifying the fuse and doublers too fit.

Whats an LJB wing?

Ya...I havn't even opened the box...but I did follow an old build along thread. I was lost through most of it.

OhBee
LJB=Lil Jumping Bean.

https://www.coxengineforum.com/t14121-guillow-s-typhoon-900-series?highlight=Guillow+s+Typhoon+900+series

First page 2/3rds down. See the two beam jig. The jig can be used for fuselages by changing the size of the rib stations.

If you are building a wing with dihedral, set the rib stations at the appropriate angle instead of 90 deg from your build surface.

If you wanted to build wings in halves, and the join them, well, just flip the cut-apart wing plan upside down and start the other side.

I'll be using this jig for my upcoming Challenger.

Oh ya...I had a Bean! One of the last planes I built in the 60's . It got abandoned in a move long ago also. .....I should build another! So many planes.....not that much time left.

Ya Ken....i learned the pick your engine first on the last one...the rest of what you described I didn't understand. Not familiar with all the terms.....I'll just leave it in the box for someone with more experience. I'd never get it finished anyway.

Ken do you know if the Goldberg shoestring kit had the shear webbing off hand , Mine is upstairs and don't want to go see right now ! If not that's ok

The Goldberg kit doesn't need shear webs. It has solid leading and trailing edges.

So what's a shear web?

OhBee wrote:So what's a shear web?  

Here you go. They are as simple as rectangles glued to the front or rear of both top and bottom spars between ribs, to as thoroughly thought out as one long shearweb with the ribs cut open in the rib for the web to pass through and then turn vertical between the too and bottom of the ribs.

https://www.airfieldmodels.com/information_source/math_and_science_of_model_aircraft/rc_aircraft_design/shear_webs_in_model_aircraft_wings.htm#:~:text=Shear%20webs%20essentially%20turn%20a,to%20the%20point%20of%20failure.

Looks like an unnecessary bunch of fiddly work that will add a lot of weight. Maybe for some high speed aerobatic application. ... Doubt it would help much augering in.

The shear webbing has nothing to do with high speed there's a lot of load on a control line wing in both up and down positions. As I mentioned to Eric, his Goldberg kit doesn't require it.The leading edge on the Goldberg kit is a solid 1" piece.  Your Brodak kit requires the bracing and I mentioned it in my above post. Reason being is that the kit is laser cut and the wood is very light and has little integrity to it. In addition, to give the Brodak wing strength, they used bass spars. However, they're on the flat which offers little to no strength over conventional 1/4 x 1/4 spars. So that the wing can have strength you have to put the shear webs in or the wing will fold in flight. It's on the plan if you look at it. They suggest diagonal cross bracing such as what you would see on floor joists in a house. That's a lot of work for what the vertical grained pieces do in half the time.

No kit is crash proof .

Why would there be more "load" on a controline planes wing than an Rc planes wing....that can do far more aerobatics?

Ken Cook wrote:
                 No kit is crash proof .

Amen to that!

I can't comment on r/c wing loads because I don't fly r/c. What I said was that there's a lot of load on a control line plane wing. Due to the fact it's tethered is one factor and the other is the wood and construction practices used to keep the weight of the model down. All new kits are laser cut. The weight of the models are down considerably compared to models of 30 years ago due to wood selection.

I have mentioned this dozens of times on here. Die cut kits used the hardest heaviest wood possible. Why? because it cut better. The lighter wood was discarded. Most sheets for ribs and elevators, etc. were all heavy C-grain. New laser cut kits use a very lightweight A grain which I've seen fall apart just from engine vibrations. I have broken ribs just launching the plane from lightly squeezing the wing. Lasers will not cut heavy wood due to burning it up. They hardly fair well with 1/8" ply and most times and your Shoestring kit has this for example is the bellcrank platform. Rather than 1 piece of 1/8" they had to cut 2 pieces of 1/16" to glue together.

The strength of all of the old profile models of years ago was due to the solid leading and trailing edges. These are no longer offered in kits. The other reason is due to wings being doped and silked or silkspanned. Now it's iron on and it doesn't strengthen the wing like the old practices did.

You can forego the webbing, and hopefully your using iron on covering because it doubles as a trash bag to pick up the pieces off of the field easier.

You can forego the webbing, and hopefully your using iron on covering because it doubles as a trash bag to pick up the pieces off of the field easier. wrote:

So True ! Thanks Ken for the info .

OhBee wrote:Ya its a Brodak!....and I don't have a wing jig !
..

OhBee what i use is a piece of dry wall to build on it stays nice and flat and you can pin your wing or what ever part of the plane your working on. Wings come out straight.  In the picture under the S Satan you can see the piece of dry all,  I used it and drew out the wing for my ringmaster, i even cut slots for each of the wing ribs to slide down into, keeps them straight.  Here is the wing for the Sig Sky ray i'm almost done with it also came out very straight.