[reluctantsparrow]

I do not know the exact details of this process, but aluminum can be "de-tempered" if needed (by precise heating and cooling). to allow for smooth bending, more than tempered aluminum would accept.

My information on the "dry ice" process came from Reynolds Aluminum in Seattle Wa....or maybe Kaiser....I talked with both outfits when determining the best way to bend the FlyBar....they strongly discouraged any bending of 6061....but then I discovered at least one HG manufacture who bends 6061 on a regular basis without going through the "bend at zero, ship on dry ice" process"....then Scott Campbell, pro bender....taught me the "radius of the die used is the key....and even though it does harden the tube...it is still plenty strong enough......just so you guys know where I picked up all this mumbo jumbo from....anyway....all that and I still did not know AU can be "de-tempered" to allow for easier bending.....still learning...thanks Red.

Thinking back,,,, older gliders never had L.E./crossbar plates. Junction plates were introduced to facilitate folding of the floating cross bars without binding up the sail at that junction...especially for double surface gliders with deep L.E. sail pockets.
L.E./crossbar plates were only introduced (if I remember right) to provide a separated junction so sails can be folded without removing that one bolt system that we always used...and without "bunching" up the sail when folded.
..we always just rotated a solid crossbar then popped one bolt through that junction (which was sleeved for strength)...and it worked just fine.
Does there have to be a plate out there? Hmmmmm...????
Here is an idea.....go back to the One bolt system but use a slightly longer junction bolt and slightly taller saddles to provide more separation between the L.E. and the Cross bar end....wouldn't take much....just enough to not bunch up the L.E. sail pocket when folded....then we have eliminated the crossbar plate completely along with the two extra bolts required.
Then pre-bend a smaller diameter Truncation Tube to slide inside the L.E. and drop in a pip pin.....
That is a pretty light weight tip solution to consider Frank.

[Frank Colver]

My tip joint is complicated by the necessity of folding the LE, the tip, and the cross spar. A plate will allow me to position the three pivot points so as to create the clearance for the three tubes to "nest" when folded. That's something I can easily change to optimise the foldability of the assembly. I'm not concerned about that as much as how I'm going to deal with the diag brace being in the same plane with the cross spar where it needs to get past. Of course there are ways to do this but one has to be careful not to create a "mickey Mouse" "rube Goldberg" type assembly here. Engineering usually supplies various choices in how to accomplish something. The real trick is to find the simplest solution. My current thoughts on this is to terminate the brace to fittings in each side of the cross spar, giving the effect of passing through the spar. I'm sure that other ideas will come up before I get to that point in the design (still way down the road). I've toyed with the idea of ending the cross spar at the LE where the cross brace connects there. That gives me concern about the bending load on the remaining LE section.

Jim, your idea about going back to the cross spar/LE single bolt and a nesting bent tip tube is also something to consider for reasons other than what you stated, as it also drops the cross spar below the plane of the diag brace. I may end up using a combination of different design ideas here. One thing I quickly discovered at the beach was that if nesting tubes have to be disconnected to pack or unpack the glider then the sand soon rears it's ugly head, by getting in the joint.

Now to the point: Please remember everyone, one reason for the design's short span is to lessen the effect of the spanwise weight. For every foot I bring the tips inward there is the corresponding reduction in the effect of the weight of the tip portion. The short span also makes the pilot's sideways weight shift more effective as a greater portion of the span. Another stated goal of the design is to reduce the sail cloth weight which will further reduce the spanwise weight since I'm trading span reduction for chord increase (keeping sail area about 300 sq ft). Then of course there is the goal of keeping the whole mess to under 40 lbs.

The other reason for the design's short span is for easier ground handling.

If successful, this glider will not be for getting from point A to distant point B it will be for getting from easy launch to easy landing with well damped pitch and quick roll ability along the way, traveling at a slow speed and low sink rate.

First step is started - building the flying model. Mike, at High Energy Sports, gave me some very light, 0 porosity, parachute cloth to use for my model's sail. It's a blinding bright orange - I won't lose this glider in tall weeds or get it run over by a lifeguard truck at Dockweiler.

Keep the comments coming folks,
Frank

[reluctantsparrow]

I already built a scale Model Frank....flies GREAT!

[Rick Masters]

  The Jesus bolt.
                                        
                                                                                        "Use my bolt, Frank, and pray."

[Bob Kuczewski]

I already built a scale Model Frank....flies GREAT!

The "Colver TruncTip" and the "Fennison Fly Bar" ... sounds like a great combination!!   

[Frank Colver]

The 1/5 scale Basic Trainer HG flying model is now under construction. It has a wing span of 65".

I have washout at the tips of 5 degrees. The rest of the reflex will come from deflexor cables to the sail TE. These are a huge advantage in flex wings. Whereas a rigid wing has a built in reflex that’s always there and always reducing the lift coefficient of the airfoil, the flex wing has almost no reflex at normal flying angles of attack and the deflexors produce reflex as the angle lowers in dives. Some is always needed to reduce pitch sensitivity for the pilot. I have the 5 degrees of twist for that and to also help delay tip stall. The center batten will have a permanent reflex set (the reason for the "Swallow Tail" like design, to get the center reflex further rearward).

After I do the tip braces I’ll start bending the cambered battens which will be from 1/8” aluminum rod. I wanted to use 3/32 dia but couldn’t find any.

Attaching the sail is going to be the most difficult task. I need to find some way to stick it to the battens. I haven’t experimented with any adhesives yet, so I don’t know what will stick to the coating.

Frank

1-5 scale model frame front view.JPG (338.01 KiB) Viewed 6295 times

1/5 scale model main frame complete.

1-5 scale model frame side view.JPG (322.49 KiB) Viewed 6295 times

[Red]

The 1/5 scale Basic Trainer HG flying model is now under construction. It has a wing span of 65". After I do the tip braces I’ll start bending the cambered battens which will be from 1/8” aluminum rod. I wanted to use 3/32 dia but couldn’t find any. Attaching the sail is going to be the most difficult task. I need to find some way to stick it to the battens. I haven’t experimented with any adhesives yet, so I don’t know what will stick to the coating.
Frank

Frank,

TIG aluminum welding rod comes in 1/16" size, and maybe smaller. You would want the straight stock in boxes or tubes, not from reels. Amazon has it, if there are no local sources.

I would suggest simply sewing the rib pockets to the sail, like a full-scale HG. Use the lightest stiff Nylon material for rib pockets, with a single line of straight stitch sewing on each side of the rib. Fabric shops will have thin Ripstop Nylon material, and extremely thin sewing threads. Cut the rib pockets from a sheet of material using an electric hot-knife (or sharpened 50W soldering iron). Make the cuts on a steel sheet with a metal straight-edge (ruler) to guide the hot knife.

HTH.

[Frank Colver]

Thanks Red.

The aluminum rod I will be using is 1/8" welding rod (alloy 4303). I purchased a box of it. They also had 1/16 but it was too flimsy.

Don't know if I want to attempt to sew batten pockets. Since I won't be removing the battens (model won't fold) it would be easier if I can tape them on after tacking them with adhesive.

Frank

[Rick Masters]

Lotta trouble to go to just to find out why hang gliders have wingtips.

[Frank Colver]

Keeps me out of the pool halls and beer joints.

F