Recent content by jaydigs

Well I reviewed about 5 different equations and kept getting 1 of 2 answers. Then it hit me, some equations were using rad/sec and others were using Hz (Duh!) That explains why I got around 70, and around 11, I was off by a factor of 2Pi. I ended up getting a critical speed of 4.3 m/s. Does...

I wonder how accurate it is to consider a flagpole as a cantilevered beam? It sort of sounds reasonable because it is fixed on on end and at 90deg to the ground, but, it isn't leaning out from a structure, and in a perfect world the only load is compressive, from it's own weight, unlike the...

Thanks for the link....that's a great site btw!

I'm analyzing a flag pole for wind loads and wanted to see what the critical wind speed was for vortex shedding. I'm using Vc = fd/s where f=natural freq, d=diameter of pole, and s=Strouhal number. I'm assuming the pole could be modeled as a cantilevered beam with fixed end? Also, I've found...

Thanks JAE!

I'm a little out of my area here, but, I'm the "hey you engineer" guy so I've been tasked to analyze the loads on a vertical flag pole. What I've done is taken the power from a stream of air ( P = .5 x rho x A x V^3) and then used the average wind speed x 10 to get the force. I'm assuming this...

I don't know why this didn't occur to me earlier, it's so simple. Thanks for the tip and I appreciate the .pdf.

I've been tasked to design an oscillator for a fan unit and I must confess this is really not my forte. I have the bar linkage worked out but I need help selecting a linear actuator. Basic requirements are to rotate a head that weights approximately 200lbs. I'm guessing the speed of the...

Thanks for the links guys. I can't read the publications without buying them but what I've gleaned from excerpts has been very helpful. Thanks again!

I was wondering if anyone had a link to some studies or data showing how effective Zinc plating is for fasteners relative to other platings or say stainless steel? In my experience I've found that Zn doesn't hold up particularly well when exposed year round to the elements but I'd like some...

Good deal, thanks for your help.

Thanks for the quick reply CoryPad. You think lower strength than the Grade 8? Grade 8 is our company standard although it's overkill. Maybe a Grade 2 or 5? Our fasteners are Zinc plated but I was concerned about the imperfections or abrasions that could remove the Zn and invite corrosion as...

I was wondering if anyone could recommend a spray coating I could use to protect Grade 8 carbon steel fasteners that will be installed in an indoor swimming pool? I'm aware of the issues surrounding chloramines and their effects on typical stainless steels, but the Duplex and 6%Mo alloys are...

Adding the static and dynamic components makes sense, but how does a fan generate static pressure? I keep wanting to think of static pressure as just the air pressure when nothing is moving, ie..atmospheric pressure. The rotation of the blades generating pressure makes sense, but that would...

This may be a trivial question to those in the industry, but, can anyone help me understand the concept of static pressure in terms of fan design and operation. From some works I've read they make it seem like something present in the environment (ie atmospheric press), and some describe it...