The Ranger, an easily built high wing LSA runabout

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Vigilant1

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  1. Bond carbon fibre rods directly to the plywood along the thickest part of the wing. This will be the spar cap.
So what one ends up with is a wing with the main spar at the thickest part of the wing, two light-weight closing-off spars front and back, and ribs made entirely of foam (the wing surface bonds directly to the foam, so no need for strips to be bonded to each rib). The wing should be incredibly stiff, and by correctly calculating the number of CF rods, one could build it to any G rating.
Duncan,
What serves as the spar web ( transferring the loads between the top cap and the bottom cap)? If I'm picturing this right, you'd have just the foam ribs and an indirect path through the closures at LE and TE.
It is the spar web (which joins the top spar cap, which is normally in compression, to the bottom spar cap, which is normally in tension) that gives the spar stiffness. Without this, you've just got very flexible top and bottom caps.
Also, the only thing to keep them from buckling (under compression) is 1mm ply to hold them straight. Maybe that's enough, I don't know.
 
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Pops

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Maybe I'm missing something, but what is to stop the epoxy from glueing the clecos in place ? So is the clecos used for glueing pressure ?
 

erkki67

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Fritz, what are the nominal sizes of the plywood sheets you are using and the quality and thicknesses.

Second, what is the travel of the shock-absorber the numbers in N to absorb?

rgds Erkki
 

FritzW

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Maybe I'm missing something, but what is to stop the epoxy from glueing the clecos in place ? So is the clecos used for glueing pressure ?
I've tried candle wax (paraffin), Carnauba car wax and Boelube. They all work fine but car wax was probably the best because it's easy to work into the cleco. You have to squeeze the cleco, stick the tip in the wax then work the cleco back and forth a little to work the wax into the little fingers. Let it dry and wipe off the excess. I've tried it with T-88 and Titebond III and haven't had one stick.

On the splice they'll provide the clamping pressure. On places like gluing the seat rails to the ply they'd mostly be for alignment. I'd still use 1/2" AC nails or clamps between them.
 

FritzW

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Fritz, what are the nominal sizes of the plywood sheets you are using and the quality and thicknesses.

Second, what is the travel of the shock-absorber the numbers in N to absorb?

rgds Erkki
Most of the ply is 1/8" AC ply (0/90 shear of 200 psi). There will be a little 1/16" AC for things like the LE skin on the overhead "wing" section.

Because of the tire deflection on 600-6 tires (or any big tires) there isn't any need for shocks. The tire deflection will provide more than enough "shock strut" travel. Hence the rigid gear on a VP-1. ...even smaller tires would work because of the lighter weight ie... rigid gear on the MiniMax and HiMax.

I think bungies or die springs on a Ranger would just add weight and complexity.
 

Pops

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I've tried candle wax (paraffin), Carnauba car wax and Boelube. They all work fine but car wax was probably the best because it's easy to work into the cleco. You have to squeeze the cleco, stick the tip in the wax then work the cleco back and forth a little to work the wax into the little fingers. Let it dry and wipe off the excess. I've tried it with T-88 and Titebond III and haven't had one stick.

On the splice they'll provide the clamping pressure. On places like gluing the seat rails to the ply they'd mostly be for alignment. I'd still use 1/2" AC nails or clamps between them.
Thanks , I must have missed it. Yes, the wax will do. I'll remember that one. I could have used it in the past.
 

rtfm

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Duncan,
What serves as the spar web ( transferring the loads between the top cap and the bottom cap)? If I'm picturing this right, you'd have just the foam ribs and an indirect path through the closures at LE and TE.
It is the spar web (which joins the top spar cap, which is normally in compression, to the bottom spar cap, which is normally in tension) that gives the spar stiffness. Without this, you've just got very flexible top and bottom caps.
Also, the only thing to keep them from buckling (under compression) is 1mm ply to hold them straight. Maybe that's enough, I don't know.
Hi,
Well, here's what the SD-1 guys have on their website:
the half wing uses GA 37U-A315 airfoil. It consists of composite main spars with carbon caps on which are glued ribs made of extruded polystyrene. It is covered with 1 mm plywood. <snip> The weight of painted wing half is 12 kg (27 lbs)
Actually, there is no "indirect" path in what I'm proposing. Each closure is constructed from 20mm x 20mm Hoop Pine with a decent shear web (exactly how the Aeromax wing is constructed). In addition, I will have the CF rods bonded directly to the plywood skin. The Aeromax wing has this structure covered only with fabric. My proposed wing has the added rigidity of a full plywood skin. I don't see any flexibility there at all.

So, in essence, it is an Aeromax/Airbike/MiniMax wing with foam ribs and a plywood skin. And the CF spar caps.
Aeromax_Wings.png
 

poormansairforce

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I think we are getting confused by where you are proposing to glue the CF? On the main spar or in space at the thickest point without a shear web to support the CF which will take the loads first being the strongest member?
 

Victor Bravo

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Sorry to stick my nose back into this discussion after I said I would not, but I'm completely confused about this latest detail. The AeroMax, and the SD-1, and most all of the renderings of the Ranger/CE concept I have seen, do have traditional load-bearing spars with a shear web and spar caps. But Duncan previously indicated that he's thinking of "cap and web shaped pieces" that are not load-bearing traditional spars, and that these are being referred to as "closures". Duncan, can you describe the parts in your proposed wing concept that will take the primary G loads? Why are your caps and webs not a "real" load bearing spar? Whether the ribs are wood, foam, or composite is a separate issue from the spar.

I'm also suggesting with 100% sincerity and high hopes that you stay focused on using the AeroMax wings you have. Investigating (or working on) a different way of building the wings is a grave error at this stage, for several reasons. The existing Ranger concept was apparently laid out from the get-go using the Ison (Max series) wing. You have a set of those wings sitting there. So there is every reasosn to continue with that wing and use your limited time and money to build the fuselage that already fits those wings.
 

Vigilant1

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FWIW, here's a picture of an open SD-1 wing under construction. It has a spar with a conventional web, carbon spar caps. In such a configuration, the direct load path between the top and bottom spar (provided by the spar web) is critical to providing the vertical stiffness to the spar.
Maybe it would be possible to accomplish the same thing by loading the skin in shear and transferring the cap loads (from caps glued to the skins near the middle of the wing) to the closures/webs at the front and back of each rib, but if doing that I wouldn't think 1mm ply would be a suitable skin.

 
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rtfm

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Hi guys,
First, the wing construction I mentioned is a thought experiment, more than anything else. I am not actually proposing building my wing this way. I already have a wing. I was just theorising and imagining. Don't you guys day-dream? There is a world of difference between serious design/buying materials/physically building something, and (as I said) sitting in a bus and whiling away an unproductive hour. VB - lighten up mate. I don't really need your caution. Yes, I have had a number of false starts, and have had to postpone my latest project (Aeromax) due to the high cost of the next sub-kit, and yes, I fully intend to use the Aeromax wings I have already built.

Don't you guys ever chase the imagination down uncharted territory? As soon as my CNC router arrives, I'll be cutting wood for the Ranger. But till then, I'll be dreaming up new and (sometimes impractical) ways of doing things. I thought my musings might be interesting. Apparently not everyone shares that view. I'll refrain from sharing further thought experiments in future I think...
 

Dillpickle

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Hi guys,
First, the wing construction I mentioned is a thought experiment, more than anything.... I'll refrain from sharing further thought experiments in future I think...
Duncan--I get it completely. I've spent my life dealing with the "SQUIRREL!" moments of ADHD. And while I've found it VERY annoying to the more pedantic engineering types who are trained to follow a line of thought to a conclusion, I have seen those little sparks of genius change entire design goals. Keep sharing man. You may have the next AHA! moment in aviation, and it may take one of the more practical engineering types who can appropriately follow the idea to its natural conclusion.

Recently in a small airplane factory where I help out and hangar rat, a very successful airplane designer, with more than four designs and hundreds of.airplanes sold, was struggling with a bit of faulty tooling. He was focused on WHY it was defective, and had spent several hours trying to determine that. In 15 minutes, I told him that I had a fix for the symptom--not a reason as to WHY the tool wouldn't work, but a work around. It bothered him. Hell, it bugs ME. But my solution is still being used. Different minds bring different cures. Keep sharing. I speak your language.

Your idea gave ME an idea. Not a Ranger specific idea, but a general thought. I think Jim Marske's sailplane spars are pretty cool. Pultruded Carbon rods layed up in a mold with a
composite web. Problems are the molds are long and messy. but...what if the mold was your light ply that became Part of the structure? Squirrel!
 

Victor Bravo

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You've gotten my intentions all wrong rtfm. I guess I should apologize for making an assumption that your comments (on building a different wing) were related to the Ranger. I made that assumption because those comments were posted in this thread (instead of a non-aircraft-specific "idea" thread), and it was seemingly relevant to the subject of wings for the Ranger.

I have no issue with discussing new ideas and chasing fantasies down into uncharted territory. It seems that actually discussing the possible pros and cons of pursuing those fantasies is causing us a problem however.

rtfm please do not refrain from discussing your thought experiments. I'll refrain from causing these problems on my end. Best of luck with your Ranger project.
 
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