Ideas for a Carbon Fiber Wing Spar, Please?

[Saddlebum]

Hi Guys;

I'm building a Senior Telemaster to use as a Club Trainer and have gotten to the wing spars. Not the spar inside the wing, but the external spars that many high wing monoplanes have that reinforce the wing to the fuselage

I'm looking for a spar that is strong and very easy to attach and release.

The setup in the kit is a wooden spar with hooks on the ends that are set into the wood and wrapped with thread in epoxy. I'm not thrilled with the strength of that.

What I was thinking of was perhaps a thick carbon fiber tube with a Dubro "Rod End" screwed and epoxy'ed into the end?

Weight is no issue but strength and ease of attachment is.

What have you done in a similar situation?

Thanks... The Bum

[JackM]

Hey Bum,

Do you mean wing struts If so it might be worth using balsa so if crashed they don't tear up the whole plane. If you want something stronger maybe spruce?

Jack

[gramps2161]

Bum a member on a build thread came up with a great way attaching the spars to the fuse and wing he used CA hinges came out great. the spars where removeable with 2 screws. I will find the thread for you later and post it.
John

[Saddlebum]

Originally Posted by gramps2161

Bum a member on a build thread came up with a great way attaching the spars to the fuse and wing he used CA hinges came out great. the spars where removeable with 2 screws. I will find the thread for you later and post it.
John

Thanks John, I appreciate it.

Are you guys flying? We had 43" of snow in four weeks and need to have the road into our field plowed!

...The Bum

[gramps2161]

All right bum did some digging and found the thread Kmot did for his build this link will take you to the page he started his struts on and start at post 81. Bum this is not with the CA hinges, but I think you might be able to still use it or at least give you a new idea as to a better way of mounting them
http://www.wattflyer.com/forums/show...t=51660&page=4

Bum we have about 3 feet of snow on the ground I won't be able to get to our club till late spring if this keeps up. We have to drive a dirt road that is close to a 1/2 mile and most of that is down hill I don't think the folks at the gravel pit plow this. To bad there is no other way for us to get down to the field to fly.
Me I have been flying off the ponds,but even these have to much snow on them.

[Saddlebum]

Originally Posted by gramps2161

All right bum did some digging and found the thread Kmot did for his build this link will take you to the page he started his struts on and start at post 81. Bum this is not with the CA hinges, but I think you might be able to still use it or at least give you a new idea as to a better way of mounting them
http://www.wattflyer.com/forums/show...t=51660&page=4

Bum we have about 3 feet of snow on the ground I won't be able to get to our club till late spring if this keeps up. We have to drive a dirt road that is close to a 1/2 mile and most of that is down hill I don't think the folks at the gravel pit plow this. To bad there is no other way for us to get down to the field to fly.
Me I have been flying off the ponds,but even these have to much snow on them.

Thanks John.

I read it through and the Pilatus boys seemed to like the E-Flite Beaver CA hinge solution. I had a Beaver and liked that solution. Leaving the struts on the wings was very convenient.

The only drawback I see is the strut has to be built perfectly as there is no adjustment like there would be if a clevis was incorporated into the system. Not that a perfect build isn't possible, it just makes it a bit more fussy.

What I am leaning toward right now is a CA hinge attachment at the wing and a DuBro strut rod with clevis at the fuselage. We'll see.

I'm still fiddling with my homemade tongue/slot/bolt system for the wing but should have that all sorted out by week end. Once that is done, it's on to the strut solution!

Thanks sent... The Bum

[Bill G]

I've used variations of this removable/adjustable aluminum tube setup on the PBY below. The added strut strength is really needed on the PBY, as the center wing mount is small.

[Saddlebum]

Originally Posted by Bill G

I've used variations of this removable/adjustable aluminum tube setup on the PBY below. The added strut strength is really needed on the PBY, as the center wing mount is small.

WOW! Now THAT is a nice setup. Strong, attractive and adjustable.

I found the streamlined tubes at Tower Hobby but can't find EZ links. Do they have another name?

Also, how can you CA a brass clevis into an aluminum tube? Is there something else in the tube?

Thanks for posting... The Bum

[Bill G]

Originally Posted by Saddlebum

WOW! Now THAT is a nice setup. Strong, attractive and adjustable.

I found the streamlined tubes at Tower Hobby but can't find EZ links. Do they have another name?

Also, how can you CA a brass clevis into an aluminum tube? Is there something else in the tube?

Thanks for posting... The Bum

The threaded rod that comes with the clevis is simply CA glued or epoxied into the aluminum tube, with the threaded end sticking out. It helps to nick the rod with cutters before gluing it in place, so that it does not spin and break the glue joint. The clevis is then threaded onto the rod. The idea is to leave a few extra threads for fine adjustment. If you find the need to thread the clevis down further after gluing everything together, then you can simply file away a bit of the aluminum tube end where the rod is glued into it.

The nylon locking clips are a Dubro part that everyone seems to carry. They come in different sizes however, so choose what size you need for the wire that you will use. I think they come in .032", .047", .060", and .072". The Dubro site shows them all.
Here's the .072 part:
http://shop.dubro.com/products/produ...5.0.0.0?pp=10&

There are lots of parts that can be used for the fuse attachment clevis. I don't think mine is a Dubro part, but here are some that would work. I just look for something with a tab that can be glued into the fuse. You can always use round tubing to make bushings to change the wire diameter to fit the clevis.
http://shop.dubro.com/products/produ...4.0.0.0?pp=10&
http://shop.dubro.com/products/produ...0.0.0.0?pp=10&

[Saddlebum]

Originally Posted by Bill G

The threaded rod that comes with the clevis is simply CA glued or epoxied into the aluminum tube, with the threaded end sticking out. It helps to nick the rod with cutters before gluing it in place, so that it does not spin and break the glue joint. The clevis is then threaded onto the rod. The idea is to leave a few extra threads for fine adjustment. If you find the need to thread the clevis down further after gluing everything together, then you can simply file away a bit of the aluminum tube end where the rod is glued into it.

The nylon locking clips are a Dubro part that everyone seems to carry. They come in different sizes however, so choose what size you need for the wire that you will use. I think they come in .032", .047", .060", and .072". The Dubro site shows them all.
Here's the .072 part:
http://shop.dubro.com/products/produ...5.0.0.0?pp=10&

There are lots of parts that can be used for the fuse attachment clevis. I don't think mine is a Dubro part, but here are some that would work. I just look for something with a tab that can be glued into the fuse. You can always use round tubing to make bushings to change the wire diameter to fit the clevis.
http://shop.dubro.com/products/produ...4.0.0.0?pp=10&
http://shop.dubro.com/products/produ...0.0.0.0?pp=10&

Silly me. I went on the DuBro website and searched for "EZ link" and got nothing, so thought it was something esoteric. If I have searched for "E/Z Link", I would have found that very common locking device we all have. Some search engines are very literal apparently!

OK, I understand how it all goes together now.

Thanks Bill, your helpfulness and thoroughness has made it clear to me (and probably a few hundred others) how to build a cool looking and rugged detachable strut.

...The Bum