horns
10-06-2009, 08:12 PM
#4
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RE: horns
Ditto. Those are nice stiff structural members and nicely made, but as Ed said those materials have lousy properties as a bearing surface. If you were to use a nylon clevis in them, the CF laminates would abrade the pins to nothing under vibration and flight loads. I like those Sullivan steel horns with the nylon insert.
Good to ask - that is a critical area in which to experiment with alternate materials.
MJD
Good to ask - that is a critical area in which to experiment with alternate materials.
MJD
10-06-2009, 09:55 PM
#6
RE: horns
I beg to differ.
The carbon is very forgiving and have been in use for years on many speedy electrics which would shame most fuel planes on this forum.
Just make sure your laminate is at least .063 thick and the best part if there is some wear or initial play a wick of thin ca will close out any slop and toughen the wear surface.
I say use them and they look great!
On the next batch I might extend the tail a bit longer to gain better glue purchase.
The carbon is very forgiving and have been in use for years on many speedy electrics which would shame most fuel planes on this forum.
Just make sure your laminate is at least .063 thick and the best part if there is some wear or initial play a wick of thin ca will close out any slop and toughen the wear surface.
I say use them and they look great!
On the next batch I might extend the tail a bit longer to gain better glue purchase.
10-06-2009, 10:27 PM
#8
RE: horns
Good point CP. Buss and chatter yes, but flight loads and flutter?
As long as the epoxy is quality, I think that is the determining factor how well will hold up. I've never had to replace one - the last thing you want to do to a hollow molded painted in the mold plane.
As long as the epoxy is quality, I think that is the determining factor how well will hold up. I've never had to replace one - the last thing you want to do to a hollow molded painted in the mold plane.
10-06-2009, 10:36 PM
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RE: horns
most of the new jets including BVM models use G10 sheet cut into horn shapes, some add brass or aluminum bushing, or they use carbon sheet in the equivalant thickness, FWIW, a lil oil wouldnt hurt for lube on the pins, also the fastest DS saoring plane suse carbon as well for control horns, because the flutter tore the G10 to pieces....hmm flutter at well over 300mph it aint pretty at all, if yah come across some chip hyde horns they are the cats azz as well they have a micro ballbearing in the horn near zero slop as well
10-07-2009, 07:42 AM
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RE: horns
There is a big difference between a solid commercial laminate like G10/FR4 and a piece of ply with lightweight carbon (it's only 2 ounce stuff) on the outside surface. Structurally I have no doubts at all they are fine for the loads. However, with thin CF on the outside the bearing surface is narrow and under considerable point load at the edges. Bushed I would rate them fine. As is I am very dubious. And if these horns have a wooden core, be careful with the lube so you don't mush up the core and make things worse.
Even solid, there are differences between laminates, as in hand layups or cured under pressure and heat and sometimes partial vacuum as is often done industrially. I've had the opportunity to make some carbon/epoxy and glass/epoxy laminates before on an OEM vacuum laminating press, and with several tons of pressure on a 12"x24" sheet you get some pretty fine material in comparison. With a good tight layup and a cleanly drilled hole (high speed and a sharp cutter) I imagine they stay fine for a long time, perhaps as long as most aircraft do. But I don't think I'd use one without a bushing of some kind to improve the bearing surface anyway. G10 might be tough but glass/epoxy is also a nasty abrasive, essentially a 50/50 blend of sand and epoxy. Watching how fast it destroys HSS cutting tools can make you worry about these things.
MJD
Even solid, there are differences between laminates, as in hand layups or cured under pressure and heat and sometimes partial vacuum as is often done industrially. I've had the opportunity to make some carbon/epoxy and glass/epoxy laminates before on an OEM vacuum laminating press, and with several tons of pressure on a 12"x24" sheet you get some pretty fine material in comparison. With a good tight layup and a cleanly drilled hole (high speed and a sharp cutter) I imagine they stay fine for a long time, perhaps as long as most aircraft do. But I don't think I'd use one without a bushing of some kind to improve the bearing surface anyway. G10 might be tough but glass/epoxy is also a nasty abrasive, essentially a 50/50 blend of sand and epoxy. Watching how fast it destroys HSS cutting tools can make you worry about these things.
MJD
10-07-2009, 10:40 AM
#12
RE: horns
For a typical speed plane with concealed elevator horn, a steel wire torque rod that joins the 2 elevator halves is pretty standard with either a flat strip of steel or brass sheet silver soldered to the axle. The DuBro nylon clevises with the hard steel pins seem good enough to bury in a plane for the duration.
10-07-2009, 12:05 PM
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RE: horns
I was playing with the cnc and wanted to cut them to see how it will look to my surprize they came out very clean.
I am going to use this first ones on a little profile plane and will see how it holds up.
I will cut some from G-10 also and see how it does.
I am going to use this first ones on a little profile plane and will see how it holds up.
I will cut some from G-10 also and see how it does.
10-07-2009, 12:52 PM
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RE: horns
I cut them just before the glue sets and di not have any sparks. The bit burned up due to spindle speed.
next time I am going to go down to 15000 rpm. The cam sugested using 22K for CF
next time I am going to go down to 15000 rpm. The cam sugested using 22K for CF
10-07-2009, 03:05 PM
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RE: horns
ORIGINAL: haikt
I was playing with the cnc and wanted to cut them to see how it will look to my surprize they came out very clean.
I am going to use this first ones on a little profile plane and will see how it holds up.
I will cut some from G-10 also and see how it does.
I was playing with the cnc and wanted to cut them to see how it will look to my surprize they came out very clean.
I am going to use this first ones on a little profile plane and will see how it holds up.
I will cut some from G-10 also and see how it does.
MJD
10-07-2009, 07:56 PM
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RE: horns
MJD and all others I appreciate all your comments and opinions.
I have the same concern for the material. I am going to do some tests and will use one as is and one with inserted brass tube and we can compare the results.
I installed them on the profile plane today. they are in there for good.
CP I am using a saito 50 on a 12.75X3.25 prop.
Also wanted to know everyone’s idea on the servo install on the tail. I wanted to hide them in the fuze so made a laminated plate and bolted the servos on. the plate will be bolted on to the fuze with 2 hard points.
I have the same concern for the material. I am going to do some tests and will use one as is and one with inserted brass tube and we can compare the results.
I installed them on the profile plane today. they are in there for good.
CP I am using a saito 50 on a 12.75X3.25 prop.
Also wanted to know everyone’s idea on the servo install on the tail. I wanted to hide them in the fuze so made a laminated plate and bolted the servos on. the plate will be bolted on to the fuze with 2 hard points.
10-09-2009, 03:28 PM
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RE: horns
What holds the other side? or is it just glued into a slot in the tail? I would be concerned about side forces eventually loosening up the horn and it popping out.
I have a little electric and horns like that have been great, but with a bigger 3d plane, those things are going to get a lot force applied to them, even with perfect geometry.
I have a little electric and horns like that have been great, but with a bigger 3d plane, those things are going to get a lot force applied to them, even with perfect geometry.
