Discusion Thread: Raceair Skylite Build and sub-kit developments

[addicted2climbing]

Hello All,

All good points and I have explored all of them already. I have multiple widget designs I have tried in CAD. The one I showed was the one that looks most promising. Making it out 6061 ends up being much heavier than the orriginal. More than 2X. The hybrind one I showed above is only a few grams different.

Here is the problem I am trying to solve. Rivet Gun access is too tight and yes it may have worked for a long time, but i imagine its a pain in the ass to bend the flange enough to get the gun in when installing. Why not just fix the issue now if I can. Also I dont have the widget tooling and single source is an issue. Another is, the guy who has to tooling supplying the widgets makes more than I do selling widgets over the plans, and I am the one holding the bag for all the questions to builders. Unsure why Ed woudl have sold the tooling since its an odd thing to part out to someone else, but sadly that is what he did.

Here are the issues and a few other designs I had.




The above show why its worth it to raise the flange a bit. However if I do it in full CNC aluminum or welded they weigh too much in relation to the originals. I am trying to not add weight or make it as negligible as possible.

Here was my first CNC version: 17.25 Grams by comparison plastic original Zytel Verison is: 9 Grams so below is nearly double.




Simple easy to make all 6061 version: 13 Grams.
I don't like that the thin edge profile on the tube interface and feel it could vibrate and grind a groove in the spar tube over time. This reason is why I went to a hybrid design that had the soft flanged surface contacting the tube yet still had a metal connection with the tabs.


I suppose rubber press forming a tall flanged version in 5052-H32 or 6061-T4 or T0 is worth a try as well. I intended to 3D print a drill jig to drill the holes in the curved surface at the correct locations. Also a slide on jig to drill the spar tube holes in the correct location and it can be slid down one location and drilled one at a time.

In regards to 3D printing the widgets, they actually print fairly fast and I can set the printer to print many at a time overnight and in 2 days have one wing worth. I am using an Ender 5 and ender 5+ that I modified to print nylon. Anyone looking to print GF Nylon can PM me for the info.

Take care,

Marc

 

[TFF]

I was figuring more of a stamped 2024 with a flange that was also the rivet bracket.

I see the rivet gun issue if ribs are assembled as whole first. If the widget is riveted on the leading edge and or trailing edge first, it probably be fine. Counter to normal ribs first building, but it is built different anyway.

There is this type of gun too PRG-26A, PRP-26A HAND POP RIVET TOOL - Hanson Rivet Online Store

There are also thing like this that can help in some situations All Products

 

[addicted2climbing]

I was figuring more of a stamped 2024 with a flange that was also the rivet bracket.

I see the rivet gun issue if ribs are assembled as whole first. If the widget is riveted on the leading edge and or trailing edge first, it probably be fine. Counter to normal ribs first building, but it is built different anyway.

There is this type of gun too PRG-26A, PRP-26A HAND POP RIVET TOOL - Hanson Rivet Online Store

There are also thing like this that can help in some situations All Products

TFF The plans call for installing the ribs with the upper area not in place since the ladder truss tubes are in the way so they cant be slid on anyhow. When the time comes for final assembly I could totally just install each widget then install the other pieces and build the rib on the wing. Thanks for the idea.

I had also looked at in hand pullers as well since they are more compact, but I was trying to make Air work. I had never seen that cam wedge before... Kind of cool.

Either way lots of good advice form you...thanks..

 

[GeeZee]

it might be easier to use aluminum rivet backing washers instead of fabricating the oblong rivet backers shown in post 13. Amazon.com: Metal Magery Aluminum Backup POP Rivet Washers for 3/16" Diameter Rivets, Pack of 250 : Automotive

 

[Tiger Tim]

Does the spar flange for the widget need to be on the same side as the cap strips on the rib? Seems like you’d have a lot more room to work if they didn’t need to be.

 

[103]

Just buy a multi cavity tool and make 6,000 at a clip! Should be under $0.25 each.

 

[PacerPlus]

I dont usually comment in here but thot I might on this "attaching method". Although I am not a proponent of "round tube spars", I have done my share of work with them over the years................. As for forming these types of parts you show drawn, the lightest way to make them with the attaching flange will be forming the 90° with either the hydroform method or a simple "die press". I havent seen it mentioned in here before is the only reason I bring this/these methods up. Forming any 90° on a radius has it's issues. A couple methods to think about is forming 6061-T6 and/or 2024-T3. If you can make a simple forming set up, hand made or machine made, you can form 6061 easily at 500° F with no real loss of structural strength......... and 500° is where you want to form, much higher may have negative results. I have done small parts by simply using a "Sharpie" marker to gage the temp, it will begin to disappear at 500°......... crude but works fine............... on smaller parts. I guess you could use one of those digital thermometers as well. Larger parts you might want to use an oven to heat the parts and form on a heated former/die. ............ no quencing just air cool. The way I prefer is 2024 but requires someone with a heat treat furnace of some sort.......... machine shops, knife makers, gun shops, etc. Take your parts to 920° F and let soak for a few minutes, then water quench within a few seconds with room temp water. Your parts will then be condition "W" which is almost the same as "O". Catch is.......... you only have a short time to work them as the begin to harden up in 15 minutes or less and they do warp when quenched. The warp isnt an issue since you are going to hydroform or die form anyway. You can suspend this W state for 2 or3 days if placed in dry ice. When parts normalize/age they will be T4 which is almost identical to T3.

As far as fastening, I would try to design to only put a rivet in the neutral axis, or center, of the spar. You can use 3M 5200, or equivenent, when riveting to the spar to prevent the chafing and movement that might occur from flexing. Plus, being in the center usually helps with any clearance issues with the river puller.

Try it on some scraps, see what you think.

I appologize if this has already been covered.

FWIW

 

[wanttobuild]

I have the plans, and am still evaluating what I would like to fly during my golden years. I always "improve" or attempt to existing designs. I have plenty of time while I am working to daydream.
The solution is Carbon Fiber. The finish of the widget does not have to be class A. Small scale "mass"production would require some thought, but absolutely doable.
That was my solution when evaluating the design.
Yes I do go to Carbon before before any other material, because the material will **** near do anything.
PacerPlus has made a bunch of very valid points. He must be schooled up on AeroMechanics.

 

[addicted2climbing]

I have the plans, and am still evaluating what I would like to fly during my golden years. I always "improve" or attempt to existing designs. I have plenty of time while I am working to daydream.
The solution is Carbon Fiber. The finish of the widget does not have to be class A. Small scale "mass"production would require some thought, but absolutely doable.
That was my solution when evaluating the design.
Yes I do go to Carbon before before any other material, because the material will **** near do anything.
PacerPlus has made a bunch of very valid points. He must be schooled up on AeroMechanics.

I was trying to avoid any Carbon Fiber to Aluminum contact due to Galvanic Corrosion. Carbon Fiber is very Noble so the Aluminum takes the hit. I was worried enough to only use Glass reinforced Nylon for 3D printing and not Carbon Reinforced for the same reason. I am sure a barrier could be painted on the aluminum at the junction, but seeing that once the wing is covered it would be tough to inspect for any corrosion that it made sense to just nix a carbon composite widget off the list. However I could be wrong and possibly Pacer plus has insight on this.

 

[addicted2climbing]

This might end up being my solution. Unsure if it can do Zytel, but if not I can explore other materials. Funny the item he shows is nearly identical to the rear rib widget in size and shape. The 3d printed molds will allow me flexibility with multiple iterations of designs as well as multiple uses during the build in the long run. Once the Tormach is up and running I can make more permanent tooling if needed.

 

[cluttonfred]

Home injection molding, that's very cool, but I guess it just depends how many you think you will need and how much it would cost to get a small run done commercially.

 

[proppastie]

Here is a shot of the rear widget using the same scheme.

you can get rivets with minimum grip of 1/32......the plastic part can be made of 2024-T3 with the notched tab method.......Bay State Rivet Co......You can eliminate 3 parts and not have a plastic major structural item.

 

[proppastie]

The top fluted piece can not have a second bend without flutes on that bend too. Everything shown can be 2024-T3 no heat treat, or plastic. My ribs held 40 lb in test.
.025 2024-T3 shown

 

[Victor Bravo]

Look closely at the Kolb widget if you have not done so already. They use stamped aluminum widgets, I'm guessing you can buy them directly form Bryan Melborn at Kolb at a good price. On more option to consider, with its own pluses and minuses.

I'd sure like to know what's wrong with using three plain 90 degree bent tabs, instead of one problematic stamping. Your time/cost/hassle would go way way down and I doubt the weight would be higher than the widget.

 

[Victor Bravo]

 

[cluttonfred]

Better yet, why not just cut sections from stock sizes of aluminum angle?

1/2” x 1/2” x 1/16” angle weighs .070 lb/foot, that’s 1.32 grams for a 1/2” wide bracket, call it 4 grams for three, or 8 grams for six (or for three twice as thick).

I think you could get away with just two brackets at each end and avoid the chafing risk on the tube by leaving a gap so only the brackets, not the ribs, touch the spars.

 

[GeeZee]

You’d probably want to set up a small press to bend one leg of the tab to conform to the spar tube. What you end up with is……..two small widgets instead of one big widget that anyone can make. I like it!

 

[Victor Bravo]

As nice as that sounds, the economics strongly favor just plain little pieces of bent angle with two holes in each one. Yes there is a slight gap under the sides of the part that is resting against the spar tube, but since there are six of them on each joint, there is little possibility of these parts "rocking" on the tube and working the rivets loose. I suspect that the loads are very low as well.

A2C can simply supply a 3 foot long strip of bent angle with holes on each side of the angle. The builder snips off the individual 3/4 inch wide pieces (using the small marker notches that were thoughtfully put into the CNC router program), and smooths the edges with a sanding block after cutting. Then these pieces get cleco'ed and pop riveted onto the holes in the forward rib gusset (which is a flat un-bent little gusset with a few holes in it). After this is done, the rib can be placed against the forward and rear spar tubes and the holes in the little tabs become drill guides to drill through the tubes.

Or, if he wants to get fancy schmancy, he can have the holes already in the tube. I found a tube laser cutting shop within 30 miles of our home airport (near LAX airport) and they are now my preferred vendor for cutting tubes (used in my certified airplane product). Considering A2C's level of genius with SolidWorks and CAD/CAM design, he can easily make all of this so these parts can be cleco'ed right out of the box.

EDIT: A2C is more than clever enough to make some of the mounting tab rivets ALSO become the rivets attaching the rib gusset to the rib capstrips. So the weight is perhaps even a few grams less, and the builder was gonna have to pull (or squeeze) the rivets to attach the gusset anyway... so the time added is also very small.

 

[addicted2climbing]

Better yet, why not just cut sections from stock sizes of aluminum angle?

1/2” x 1/2” x 1/16” angle weighs .070 lb/foot, that’s 1.32 grams for a 1/2” wide bracket, call it 4 grams for three, or 8 grams for six (or for three twice as thick).

I think you could get away with just two brackets at each end and avoid the chafing risk on the tube by leaving a gap so only the brackets, not the ribs, touch the spars.

Using stock angle was my plan but I was trying to find .032" but woudl go .063" if needed. I also thought of leaving the gap as well to avoid chafing. On my jig I can add a small strip of plastic to build the offset in when the ribs are built. changing the front clip to just one connection point but on either side my be a good idea. Currently the front rivets are offset from the center of the tube and if I went with one location would it make sense to still offset from center a bit or just drill dead center?

 

[proppastie]

I will try my hand at building a traditional rib per plans.

I am somewhat confused here...... this is one of the aircraft you purchased the rights to.......If so there already is a set of plans with a rib drawing.....so this rib discussion is "new design"? .....Perhaps a post of the original rib drawing would be helpful here to add perspective.