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03-07-2018, 02:35 PM
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Join Date: Jul 2007
Location: Litchfield Park, AZ
Posts: 1,019
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Quote:
Originally Posted by Saville
What we really need is a production-made steel curved stick that has the 2" or so set back built into it.
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Are you reading this Russ McCutcheon?
__________________
Carlos in Arizona
EAA Chapter 538 www.chapters.eaa.org/eaa538
Wittman Tailwind W8 N53CH (built & sold)
Pazmany PL-1 N2029 (bought & sold)
RV7 - N537TC (reserved & building)
Emp, Wings & Fuse done - working on FWF
"The air is an extremely dangerous, jealous and exacting mistress. Once under the spell most lovers are faithful to the end, which is not always old age." - Winston Churchill
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03-08-2018, 06:42 AM
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Join Date: Apr 2014
Location: Columbus OH-IO
Posts: 111
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Mark,
I would love to help with this or any of your other ideas to incorporate 3D printing. If you have the resources to create the CAD design within your business, we could help with the printing of the prototypes and final part. Shoot, even if you don't, we can help with the design here. We have the new HP Multi Jet Fusion 3D printer and we are able to print parts in production nylon pa12. This material and process will without a doubt be strong enough to handle the job. Also with this material, unlike other 3D print materials, will withstand time in the sun without any deterioration in properties. This is a durable and high temperature resistant nylon, just as when used in injection molding. I will post a link more info on the machine and process. Give me a call to discuss when you get the chance. 614-834-8659
http://aerosportmodeling.com/hp-jet-fusion-3d-printing/
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03-08-2018, 09:03 AM
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Join Date: Jun 2006
Location: 8I3
Posts: 3,564
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Quote:
Originally Posted by Saville
What we really need is a production-made steel curved stick that has the 2" or so set back built into it.
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Had the same issue on my rocket. Cut apart the front stick weldment, moved it back 2-1/2", TIG welded it back together. Done. No bent stick necessary.
__________________
Please don't PM me! Email only!
Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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03-08-2018, 10:48 AM
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Join Date: Apr 2012
Location: Collierville, TN (KFYE)
Posts: 1,433
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This is experimental aviation, right? Well, here's an experiment:
Yes, those are copper 45 degree elbows acquired in the plumbing aisle. Since those elbows are 1-1/8" ID and our sticks are 1" OD, I have used sections of scrap 6061 aluminum tube as bushings. It's actually from my first attempt at making the long elevator pushrod. That tube is conveniently 1" ID and 1-1/8" OD. Perfect for what I wanted. All riveted together with LP4 pop rivets (as also used on the elevator push rod).
Needless to say, it's pretty "industrial" looking and I will dress it up and re-attach my Infinity grip. I'm sure it's not what you'd want in an Extra 300, but I think it will be more than adequate for what we do in an RV.
OK, you may go ahead and start laughing! 
__________________
RV-8 #81077 Super Slow Build
Dynon Skyview HDX, Titan IOX-370, Dual P-Mags, AFP FM200A FI, Whirlwind 200RV CS Prop
First Flight 11/20/2016
www.marksrv8.com
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03-08-2018, 11:44 AM
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Join Date: Dec 2009
Location: Boulder, CO
Posts: 4,435
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How are you going to test that thing?
What limit loads and what load cases will you use to test it - and what test factors of safety?
Dave
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03-08-2018, 11:52 AM
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Join Date: Apr 2012
Location: Collierville, TN (KFYE)
Posts: 1,433
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I have no plan at this time to conduct scientific load testing nor do I think it's necessary for the plane I fly or the way I fly.
__________________
RV-8 #81077 Super Slow Build
Dynon Skyview HDX, Titan IOX-370, Dual P-Mags, AFP FM200A FI, Whirlwind 200RV CS Prop
First Flight 11/20/2016
www.marksrv8.com
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03-08-2018, 01:53 PM
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Join Date: Dec 2009
Location: Boulder, CO
Posts: 4,435
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Brave man. Very brave.
If you mount the stick on its side so it's horizontal and put your full weight on the new end, that would be a reasonable test. Then rotate 90 degrees and repeat.
Dave
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03-08-2018, 03:09 PM
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Join Date: Apr 2012
Location: Collierville, TN (KFYE)
Posts: 1,433
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Quote:
Originally Posted by David Paule
Brave man. Very brave.
If you mount the stick on its side so it's horizontal and put your full weight on the new end, that would be a reasonable test. Then rotate 90 degrees and repeat.
Dave
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I'm no engineer and can't get into a debate about things I really don't understand, but I'd ask that if a control stick has to be able to handle close to 200 lbs of pressure on the long end of the fulcrum, would that not translate into a significant amount more on the short end? This stick measures about 20 inches long. I don't have it handy to measure, but I'd guess 2/3 is on the long end of the fulcrum, roughly speaking. That means that the long end is about 13.5" and the short end is 6.5". 185 lbs (which is unfortunately what I weigh) would translate into a force of close to 385 lbs, right? Again, I'm not educated in this stuff and it's been a long time since high school physics. So, what I hear you saying is that unless you can apply 385 lbs of force to the aluminum elevator bell crank structure and the elevators themselves, that stick isn't strong enough? My humble opinion is that if I need to apply that amount of force to the controls, I'm already dead and in a smoking hole.
__________________
RV-8 #81077 Super Slow Build
Dynon Skyview HDX, Titan IOX-370, Dual P-Mags, AFP FM200A FI, Whirlwind 200RV CS Prop
First Flight 11/20/2016
www.marksrv8.com
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03-08-2018, 03:27 PM
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Join Date: May 2006
Location: Pocahontas MS
Posts: 3,884
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I suspect that you have the force levels/locations reversed. The farther out on the lever, the lower the force, and longer the throw required.
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03-08-2018, 06:42 PM
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Join Date: Apr 2012
Location: Collierville, TN (KFYE)
Posts: 1,433
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Quote:
Originally Posted by RV8JD
As a guide, let's look at 14 CFR ?23.397, "Limit Control Forces and Torques". It says the maximum loads on the flight control surfaces must never exceed what would resullt from the given pilot forces. It gives the maximum (limit load) pilot forces for a stick as 167 pounds for elevator input, and 67 pounds for aileron input.
Also, 14 CFR ?23.395, "Control System Loads", states that " ... Pilot forces used for design need not exceed the maximum force prescribed in ?23.397(b)." And that "Pilot forces used for design are assumed to act at the appropriate control grips or pads as they would in flight ..."
The control stick should be designed accordingly.
--> So David Paule's suggestion that the stick should support one's weight is not a bad approximation (as long as you are about 250 pounds)! 
(The 250 pounds is the Ultimate Load which is equal to the Limit Load of 167 pounds times the 1.5 Factor of Safety usually applied.)
(Yes, I know we are Experimental and the FAA design CFRs don't apply, but ignore them at your own risk!)
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I hear all of that, but under what reasonable scenario in the planes we fly will 185 or 250 lbs be required? I fly my plane with my fingers. If I'm applying 10 lbs to the stick, I'd be surprised, much less 185 lbs. You are right, this is experimental aviation, just as I said in my first post today, sentence #1. Many planes owned by builders on this site have been built with parts obtained from the famous "aviation aisle" at Lowes and Home Depot. Not exactly approved by the FAA there...let's not talk about experimental engines, props and all manner of other stuff that doesn't comply with the CFRs...that's why we're EAB, and I gladly accept any risks that arise from my many experimental modifications on this plane. It's what I love about doing this. I've owned 5 certified planes and they all were boring, boring, boring compared to this and part of it is that I have the ability to make this plane mine in my own way.
In re the stick, I will be cautious and in the very unlikely case that my crappy shade tree engineering fails, I'll slide my hand down 6 inches to what's left of the official, highly engineered and tested piece of 4130 steel tubing provided by Vans, and then land the plane!
__________________
RV-8 #81077 Super Slow Build
Dynon Skyview HDX, Titan IOX-370, Dual P-Mags, AFP FM200A FI, Whirlwind 200RV CS Prop
First Flight 11/20/2016
www.marksrv8.com
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