wolfy
Gold Supporter
Does anyone know of a formula for calculating the column strength of 5/8 x 065 4130 tube?
I am wanting to use 5/8 x 065 for my control rods.
Thanks wolfy
I am wanting to use 5/8 x 065 for my control rods.
Thanks wolfy
I will have to measure them but they won't be long because of bell crank near the middle.how long will your controls rods be ?
compression don't play an important role in the control rods in my opinion , as a mater of fat the rotor want to get flat and you have to pull the stick ant the rods to increase the rotor backward angle.
when you put your stick right the it pulls down the right rod , ok, it pushes the left rod but it is marginal.
Thanks Jc I will look it up.When the tube working in compression is long, the Euler's formula should be used in which it is the modulus of elasticity E that is critical. The breaking stress is not critical.
Thats a fair idea John, as apposed to round the square section has the added rigidity. Not good for mast's but use full in that respect.I switched from round tube to square thin wall aluminum tube for my control rods. I think I'm using im using 1" x .065 square tube now. Seems to be working OK for me so far. My control rods are fairly long and it vibrates less than round. I also have added dampers too.
Thanks mate I should have that info after I start making them this weekend, I will let you know the lengths it will be interesting.if your rods are in 2 parts, they will be strong enough,
the worst enemy are the vibrations ...
if you give me your flight rrpm and the exact length of the half bars I can ask my mate to calculate the 2/rev vibes modes to verify they are not destructive
on my monoseater there are vibes but not in flight , they vibrate with on the ground when the engine is idle ... it is impressive...
once the tandem is in action I will get back my gyro in my garage and overhaul it and change the rod bars, build a lighter engine mount (it will make JC smile hahaha) etc
Excellent thanks mate looks perfect, I was advised I could use even smaller tubes (both diameter and wall) by some one very knowlegdable and that I trust but I just needed some re assurance as they just look small.Hi wolfy,
I did a simulation on fusion 360 simulation module applying a 1000N force ( 100 "kg" approx) to the top of the tube ( steel 4130 at your sizes), tube length 1.2 meter
the tube is constraint at the bottom in all axes (as it if was dug into concrete) .
doing so the displacement is only appearing at the top of the rod and is negligible (0.05 mm !) , on the picture the displacement is exagerated by the computer to make it possible for users to see it (otherwise it would be too small to be visible).
the computer states a safety factor of 15 up to elastic limit ( not up to rupture)
I hope I have correctly entered all parameters in the module but all of this seems OK.
stress distribution is even (see the second picture it is oranger everywhere)
400 N is the german command resistance requirements for the dulv (certifyin body in germany) when DTA certified his gyro dta
View attachment 1149080View attachment 1149081View attachment 1149082
that is how I made all my CNC equipment. Started small while still working on my degree in CNC R&D Machine Development.autodesk fusion360, they have added this module in 2016, they have purchased the system, it is really reliable, you can spot the weel areas and and fillets chanfrains, put more metal, remove some when it is not necessary ...
I think that the fre version does not permit the access to this module (to be checked)
I am using it to design and to generate the G code to drive my cnc ...
I am making a bigger cnc at the time ... an other game
Sorry, I am not familiar with English units.Thanks Jc I will look it up.
Do you think 5/8 x 065" will be strong enough for a medium weight single seater?
No Jc 15.9 mm is the outside diameter and about 12.7 mm for the inside diameter. 0.065" (about 1.6 mm) wall.Sorry, I am not familiar with English units.
Are you talking about a tube of 15.9 mm inside diameter (5/8 ") and 16.5 mm outside diameter (0.65") ?
The square tubing sacrifices a small amount of MOI for an increase of inplane stiffness. Well worth it in my opinion, I doubt I'll go back to round tubing. The simple compressive calculations don't account for the round tubings greater flex in real use vibrations. Both sections can do the job and the only compressive failure for any shape on a gyro control rod I'm aware of was with someone who bent the tubing itself for clearance to avoid splitting the control tube into 2 sections. It wasn't a catastrophic failure, they noticed the stick position had changed and found that the bent tubing had bent even more.Using square tubes for the push rods means you sacrifice some strength since the moment of inertia of the square tubes is smaller for the axes that go through the sides of the cross section compared to those passing through the corners. The best cross section for a compression column is a circle.