Wingtip Weightloss Program

[racaldwell]

First fit up of lightened wingtip

Success. I had a goal of 50% weight reduction for the 14.7 lbs each stock wingtips. Now got one almost complete and it weighs in at 6.5 lbs. Other than a battery change, I can't think of anything else in the airframe where a 15 lb weight savings can be had. I wanted to learn something new so I am trying my luck with vacuum infusion. I am convinced. It is one slick way to make composite parts. I am also learning new ways to make mistakes. But I am hoping the 2nd wingtip will go smoothly. I used S-glass/vinyl ester resin for the skins and S-glass/epoxy for the rib facing & all the joint bonding. I also put in an embedded al. strip so the hinge rivets will have metal to hold onto instead of just fiberglass. After the 2nd tip is done, I can finally move on to the fuselage. These wings have been a really long journey.

[Bryan Cotton]

Awesome. I saw a lot of vacuum bagging at Sikorsky. We tried to do a simple vacuum bag setup for my younger son's hovercraft rudder but we failed.

[NWade]

Lookin' Good!

My buddies over at the HP-24 kit sailplane project discovered the joys of resin infusion under vacuum a few years ago, and swear by it. The real challenge they fought in the beginning was vacuum forces setting up an unintentional twist in thin parts (like long thin small-chord ailerons) - so that's something to watch for. But they've got a really good production setup these days.

Did you splash a mold off of the factory-supplied tips; or did you use some other method to come up with the tip-skin shape?

--Noel
Sonex #1339

[racaldwell]

Noel,

I made my molds around the Sonex tips. I wanted to make sheared elliptic tips but then I also want to finish my Xenos within this decade so decided I could come back to the tips after I get flying if I still feel expereimental. The vacuum pressure is intense. I learned that I needed to put some cushioning under the spiral wrap used as resin runners because the pressure made slight indentations in the mold surface. It wasn't a big deal for me as the molds are not production ones and probably won't make any more parts out of that one. The skins by themselves are rather floppy so if there is a twist in an individual skin, I didn't notice it. When I mate the two skins together with the four ribs and glass it all together inside the clamped together mold halves, then is becomes one solid part.

Rick Caldwell
Xenos 0057
Melbourne airport

[racaldwell]

Noel,

Thx for sending the link for the HP-24. Real interesting project they are doing. They have put in some major effort in getting to where they are today. Of course, I want one!

Rick
Xenos 0057

[NWade]

Noel,
Thx for sending the link for the HP-24. Real interesting project they are doing. They have put in some major effort in getting to where they are today. Of course, I want one!

Rick
Xenos 0057

Feel free to reach out to Bob K - he's a great guy! I'm sure he'd be happy to sell you an HP kit and even have you come over to California to help lay it up (they get together a few times a year with builders to do hands-on workshops over weekends, laying up the fuselage and wing skins and such). They've got 3 or 4 ships flying now, and at least 2 or 3 more in the finishing stages. One of my local pilot buddies has been flying the prototype for 4 years now and loves it! If you know sailplanes at all, its performance is slightly better than the famed LS-6; but with better rigging & flying qualities.

BTW, Bob might also have some tips on how to regulate the vacuum pressure so you don't leave indentations in your molds/parts from the spiral wrap.

Good luck with the Xenos build! Should be a real fun cruiser & part-time soarer when you're done with it. Definitely let us know if you build those elliptical tips - they'll look sharp I'm sure!

--Noel

[racaldwell]

I finished the 2nd wingtip and drilled to the hinges this past weekend. Of course the 2nd on came out better. Overall, I saved 15 lbs off the wing weight. That made it worth the cost & time. It is nice to be able to handle a tip with one hand. The hinges are a pain to get aligned when installing the tips. I need to file all the eyelets at a bevel to see if that helps. It's also a pain to have to disconnect the aileron to get access to the tip attach hinge pins.

Rick
Xenos 0057

[NWade]

Looks great, Rick! Hope they provide you with a lot of happy fun soaring time. :-)

--Noel

[epvans]

Do you have any pictures of the Xenos Utility Wing Tips. I would like to see how they are attached to the wing. Sonex says easy removal if you have a 40 foot hanger so I was curios to see how they attached to the wing

Thanks

[racaldwell]

They are attached with a piano hinge. Took some work to get them to slide in & out without too much trouble but now it is a few minute job.

Rick