Following a request from Tim for a bigger (60" span) version of my MO-1, I though it might be worth a thread of its' own during the development stages.

Due to a dearth of decent 3 views of the type this will be another sport scale model and based entirely on my smaller design, which was based on a rubber power design.

I've scaled the original drawings, roughly doubled the number of wing ribs and am just starting to consider how I'd like it all to go together. I don't really feel that a one-piece model would be particularly practical (for many builders) at this size, so the first thing to decide is how the wings will mount.
On the 30" model, the wing is built as a single unit, that glues into the fuselage. However, that does require fairly precise building to get it to fit properly. A similar system could be used on the large model but, since it would have to be bolted in place, that means exposed wing bolts right where they are pretty darned obvious - on top of the c/s.
My current thinking is that plug on wing panels would be easier, and avoid the need for such precise building. This, however, introduces problems of its' own. Firstly, because of the lack of additional bracing, whatever I show is going to have to be fairly rigid. Secondly, for precisely the same reason, there has to be something actually holding the wings in place.
I've done a little searching (it only took one model oriented site to find what I was looking for) and am considering carbon tube within carbon tube - 10 mm tube joiners within 12 mm tubes mounted in wing and fuselage. That should hold the wings rigid enough, since since just one 1 metre length of each would mean they would extend at least 20% of the span of each panel, but they still need holding in place against the fuselage sides.

I'm open to suggestions at this point, especially from Tim since he'll be the one building it. It could be I'm just over thinking this one. Afterall, it isn't supposed to be aerobatic, so maybe smaller (cheaper) tubes would work. I'd just hate for someone to pull one loop too many and have the wings shear off.

Pete

Why not put the threaded wooden part in the wing and screw in from below? I use that on my Sylph sport plane. I hid the end of the bolt within the pilot, which would work since the MO-1 has an aft gunner's cockpit, correct?

Access to turn the bolt is from the bottom, through a paper tube. We've been flying the Sylph for about five years, and not had any issues with the bolt arrangement.

CD

Pete,
My only thoughts are that the wings are indeed removable and the simpler the better.
The aluminum / CF tube arrangement in the Pietenpol is holding up very well after 2 plus yrs.

Tim (jazzed and looking forward to the build )

CD,
Thanks. I had quickly considered bolting from below but discounted it. I may yet re-think that option.

Tim,
Yes, I figured you'd want to be able to dismantle the model. No doubt I'll come up with something workable.
Any idea what motor you'd like to use? I was considering showing the AXI 2814, like the Piet, so I suppose your Turnigy would fit much the same.

Pete

Pete,

The only reason I'd not suggest the larger nested CF tubes is the difficulty in procuring them for the avg builder. But, I can also see where that might be the best solution. Just don't use CF arrow shafts. BTDT with not good results

charlie

Charlie,
Granted that those are the two largest listed on the site I checked, but the site (J. Perkins) is one that supplies a good number of UK model shops. If they list it as in stock, I would expect most other distributors to as well.

Peter,
For the motor, I'm looking at the EMax 2820. It appears close enough to the Axi 2814. Lazertoyz is local so I don't have to pay shipping.
http://www.lazertoyz.com/shop/GTmotors.htm
As for the CF tubes, as long as you have it worked out by Apr 13th, we'll be in good shape.
This year's Weak Signals is Apr 13 -15. There are usually multiple vendors selling all sorts of CF, in all shapes and sizes.
http://www.toledoshow.com/
Speaking of Weak Signals, Charlie have you ever thought about attending? I know it's a bit of a hike from NM but could be worth your while. Besides Toledo in April is not to be missed.

Tim

Pete,
With a battery hatch on the top between the wings you could bolt/screw the wings to the fuse sides... Through the side and into the end rib...
Paul

Tim,
I'm pretty much set on the tube in tube set-up, so just find some 12 mm o.d tube (carbon or aluminium) and whatever size carbon tube fits inside it well. You'll need about a metre of each (or 3 feet) but the longest single length you'll need will be about 15 inches for each of the carbon joiners.

I did think about bolting the wings from inside the fuselage, but it isn't that wide and might give screwdriver access problems. One similar idea I was considering was a drilled dowel fitted to the wings, that passes through the fuselage sides and has a buggy style R-clip fitted to prevent the wings moving out on the tubes.
Another option is brass straps running through the fuselage, bolted to ply plates. Then you'd just slide the wings on and fit four screws/bolts to the bottom of the wings to retain them.

Pete

Tim,

I have thought about going to Toledo and WRAM (and Rheinbeck and others), but, I do have a day job so vacation time is just not available for such a venture.

charlie

Okay, wing fixing is decided; tube in tube joiners and four retaining screws. That keeps the area between the tube clear so that the battery can be accessed from above and sits pretty much directly below the balance point. Therefore, balance should remain acceptable no matter what pack you fit.

Wing ribs are all basically plotted and now just need tracing and nesting into wood size panels. Spars are another matter entirely. Because Charlie is limited to 24" lengths of bass, and I'm not keen on the possibility of too soft balsa spars, the spars may need a little thought if they are to be included in the parts.
I considered laminated ply spars, but the thickness issue would cause problems. Although the rear spar has a join in it anyway (because of a bend), I'd prefer the front spar to be a single piece. However, if you want them in the parts, it will have to have a join. I may show a one-piece item on the plan (for those cutting their own parts) but include the parts and braces, along with a note on the plan, for those who want ready cut spars. What are your opinions on the subject?

Pete