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Anker
83 Posts |
 Posted - 06/06/2003 : 11:50:54 AM
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If you build the Mark Drela/Phil Barnes Aegea wing and mate it with a Tery Luckenbach fuse you should reinforce the tube extension at the back of the pylon. Fritz Bien managed to break his fuse at this point and mine has stress cracks. I recommend cutting a piece of mylar so it wraps around the tube and up the sides of the pylon.
Anker |
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Jack Hyde
8 Posts |
Posted - 12/03/2003 : 8:26:57 PM
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I managed to pull out the part of the pylon which the nut for the wing mounting bolt is attached to when I was launching last month. The wings floated down from 400' and were unscratched. The fuse came down like a javelin. The boom broke at the rear of the pylon and just forward of the tail. It was all pretty easy to repair and doesn't even look bad. I pinned the piece that broke out with 1/2' long 1/8" dia steel pins epoxied in place. It has lots of flights on it since the fix . No problems so far. Pretty tough plane.
Jack Hyde
Red Bluff,CA |
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Jeff_Newcum
7 Posts |
Posted - 12/04/2003 : 09:34:04 AM
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Some of the CRRC members started building their Mantises last night.
Fritz provided the guidence, conversation, and wood. We just brought beer, pizza, and pretty fuses.
We started out creating the spine for the control rods that will be inserted in the boom and finally CA'd in place.
First we used 10 pieces of 0.97"X3.2"X1/16" blasa, 32" in length, laid side by side and CA'd (endgrain ran vertical). The butt gluing was done against a yardstick to guarantee alignment.
Next we added two balsa strips across the soft balsa to the center on both sides and CA'd. The stripper was set at .156" on the 3/32" piece of wood
We then added the teflon control rod sheath. Masking tape was added every 3" or 4" then, it was CA'd to the balsa strip
And here is the completed piece.
Fritz also was working on his v-tail mount.
Here is the removeable tail setup.
And here are the drawings for the tail setup by Fritz Bien
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Edited by - Jeff_Newcum on 01/07/2004 11:47:21 PM |
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Anker
83 Posts |
Posted - 12/07/2003 : 7:31:30 PM
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Jack,
Something I wasn't aware of until the same thing happened to me wwas that the hold-down block must butt against the bottom of the wing. If you leave a gap the stresses on the holddown block will be the som of the bolt pull and the winch line pull. If they mate the stress is only the winch line pull!
Anker |
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jgleigh
2 Posts |
Posted - 12/09/2003 : 1:01:49 PM
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| Is the spine in the boom structurally necessary (to stiffen or strengthen it), or is it just there to carry the pushrod sheaths? |
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Jeff_Newcum
7 Posts |
Posted - 12/09/2003 : 1:15:52 PM
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I remember Fritz saying that it was for additional strength in the boom. Though, I've never seen a boom fail, I do think it's a slick method and there is no significant weight penalty. It seems that this method also minimizes the play in the control rod.
Additonally the stick is inserted into the boom with the boom seams on the horizontal plane.
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Phil Barnes
100 Posts |
Posted - 12/09/2003 : 1:30:02 PM
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I am going to E mail Terry Luchenbach about the balsa spine question. I was originally going to post that the spine was only to suport the pushrod tubes but then I noticed that the balsa spine is on Terry's plan sheet and it specifies vertical grain balsa. You wouldn't bother with vertical grain balsa unless it was there for structural reasons. I still suspect that the boom would be fine without the balsa spine and that the balsa only makes it a bit stiffer. Let's see if Terry can enlighten us.
Phil |
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Phil Barnes
100 Posts |
Posted - 12/09/2003 : 8:21:45 PM
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The following response is from Terry Luchenbach in reference to the balsa spine question:
>I have not tested the stiffness with and without the spine. I think >it would be fine without it, but I'm sure it adds a little >stiffness and maybe better crash resistance.
I expect that Terry will be joining the group soon.
Phil |
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Fritz
19 Posts |
Posted - 12/13/2003 : 5:41:28 PM
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My thoughts on this: Since you want to glue down the sheathing anyway, and you're adding a piece of 1/16" balsa to do so, the vertical grain provides stiffness that grain along the boom does not. The stiffness is therefore free.
Furthermore, vertical grain is easily made, and doesn't get chewed up if you slide it in and out to test proper fit. or in case you forgot to put something in, in the first place.
-Fritz |
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kiesling
45 Posts |
Posted - 12/17/2003 : 7:56:27 PM
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As Fritz says, the stiffness is for free so you may as well use it.
However, the boom is plenty strong and stiff without the shear
web.
The vertical grain is important for the buckling resistance
of the pushrods. If the grain ran horizontally there would
be a risk of the balsa splitting and providing little/no resistance
to buckling.
It is a bad feeling when you go to pull out of the zoom dive and
nothing happens because your pushrods have buckled . . .
Tom |
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Jeff_Newcum
7 Posts |
Posted - 01/08/2004 : 10:20:43 AM
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I recieved Phil's beautiful Aegea wing and Tail for Christmas.
I started building up the tail last night at Fritz's.
First I cut a piece of basswood for the center spacer for the tail. Then I drilled two more holes on top for the mounting 6-32 mounting bolts. I then counter sank them and taped the tails near the bonding area to avoid excess glue on the tail.
Here is the buiding detail from Fritz:
"The first hole is drilled to align the hole in the stab as provided by
Phil. The block was slightly larger than need be, to be trimmed later to
match the stab shape. We got it too close :-).
The hold-down holes were 3/4" in front of this hole and the second 1.5"
behind the first hold-down hole. Measurements are done in that order so
that the 1.5" spacing is the governing dimension, and not the precise
position of the centering pin with respect to the hold-down pins.
Before you paint your tail, or glue on the ply pieces, you want to put a
layer of Kevlar/glass about 1" wide both top and bottom of the joint. That
will secure the joint and prepare you for the next step, which is to glue
the block to the fuse."
I then mixed up some 15 minute epoxy and applied it to both surfaces and slowly mounted the tails on the joiner. I used the TLAR method for alignment on the tail. Once the glue was set I removed the tape.
Here is the tail so far.
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Edited by - Jeff_Newcum on 01/08/2004 10:43:51 AM |
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jon stone
12 Posts |
Posted - 02/21/2004 : 2:47:16 PM
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| Where are all the pictures in this thread? All links seem to be broken. |
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Jeff_Newcum
7 Posts |
Posted - 03/04/2004 : 10:02:53 AM
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Back to building....
I was back at Fritz's last night. He helped me with the pylon build.
First, I needed to cut a piece of maple to fit the width from side to side. The inside width was measured and scribed on the wood. Prior to cutting I found the center of the piece and drilled a hole from top to bottom with a 5/16 bit. Once completed I cut the piece on the bandsaw and test fit in the pylon. I sanded the top corners of the block till the top was flush with the top of the pylon. I then pressed the blind nut into the bottom of the block. Once it was in I applied some thin ca around the blind nut and repressed in the vise. The edges of the blind nut were then ground down to be flush with the block.
Top of block
Bottom of block - blind nut is not ground flush yet
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paul
13 Posts |
Posted - 03/04/2004 : 6:17:30 PM
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| Not sure of Terry's intent, however....The end grain balsa is free to expand and contract as the fuselage bends and soaks up little load. The failure modes of the tube in bending are pure torsion or buckling. The end grain balsa provids more stiffness in the vertical direction to support the tube agaisnt buckling than longitudinal grain would. Lastly I like tom's thought on the potential for failure of the longitudinal grain balsa and then having the pushrods hangin in the breeze. |
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paul
13 Posts |
Posted - 03/04/2004 : 6:19:09 PM
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| Sorry, should have said the failure modes are pure tension (not torsion) and buckling. |
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gldrgidr
22 Posts |
Posted - 09/28/2005 : 12:00:07 AM
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| I have a Luchenbach fuse and would like to see Jeff's Photos. Anyone know what happened to them? |
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flyeslhost
158 Posts |
Posted - 09/28/2005 : 04:40:16 AM
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quote:
Originally posted by gldrgidr
I have a Luchenbach fuse and would like to see Jeff's Photos. Anyone know what happened to them?
Yes, Jeff use to have his own website, which later was taken by CRRC. At this forums you can upload your picture here or reference them from another location (website). He chose to reference the pictures, now the site is gone, so are the pictures.
People are encourage to upload their pictures here, so there is a permanent record of their contributions.
Jeff, if by any chance you read this and you have the pics archived, send them we could upload them, or if you have the time, update your posts.
Thanks
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Jeff_Newcum
7 Posts |
Posted - 07/28/2009 : 3:11:49 PM
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| Sorry about hot linking to the site. I know this info is a bit dated but, I'll look through my images and try to update this post. |
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aeajr
477 Posts |
Posted - 08/11/2009 : 08:39:44 AM
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Did you find the pictures? I am sure there are owners out there that would find them useful.
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Best regards,
Ed Anderson
Long Island Silent Flyers
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Topic |
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Building the Aegea glider
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