Two propellers in series will not be very efficient, although I suppose if you increase the pitch of the second it might help. Putting a 2 bladed prop into a tube turns it into a ducted fan of sorts.
Conceptually think of the bar as a series of springs and masses. As the mass hits the ground the spring above it compresses, and so on and so forth up the chain of springs and masses.
As you can see there's a series of compression and rarefaction waves set up in the system.
It looks like it...
"It used to be the case that large EPC contracts would be bid at cost or even below and the contractor would make his profit on the variations and additional work." One company I worked for had this down to an art form. Bid at almost zero profit, then encourage the customer to upgrade the design...
Every marginal kWh of electricity used is generated by fossil fuel. I was wrong above, coal is not in the absolute majority, but fossil fuels are, and continue to supply 60-70% of electricity.
"People can also choose to adopt electric vehicles since road transport is responsible for about 12% of greenhouse gas emissions worldwide"
Hmm, and since most electricity is produced by burning coal then there seems little likelihood that this stupid idea will make much difference.
Here's the...
Consider it as a 2dof spring mass system. m1 k1 m2 k2 ground all in series, with m1 subject to some dynamic force. The ratio m1 to m2 is important, and for good isolation should be as small as possible. Hence isolating at the base is more effective than isolating the whole platform.
I agree about the minimum age/experience needed.
We got heavily into SE 30 years or so ago, but rather than having dedicated SEs we all used the tools (with varying degrees of competence and enthusiasm). On the mechanical side we mostly didn't bother with interface requirements and the like...
In my opinion (that and $6 will get you a cup of coffee) SE is a great discipline...if you are an SME. Otherwise you end up being the keeper of checklists and documentation, death by spreadsheet.
"For years, successive premiers and energy ministers have talked about the potential of using the tides in the Bay of Fundy to create renewable energy, but there's been little to show for that talk other than bankrupt companies and busted devices."
Indeed, same story all around the world...
Yes, when they decommission the wind turbines in Australia, often built on prime farming land, they take the actual turbines away, but all the foundations and the rest of the mess gets left behind. I guess they take the copper. The usual method to avoid having to pay for cleanup is to sell the...
Back to the 15:1 truss.
Here's the member force diagram for a 45x3 pin jointed truss that looks vaguely like the original, with 100 load units applies vertically to each node along the top members, reacted by 400 at each end
ie ca 10:1 load magnification in the end bay, as you'd expect...
gamma (ratio of specific heats) of helium and nitrogen will be different. So unless you are doing an isothermal experiment then you'll need a more complex correction to get the performance with helium.
Preload doesn't affect the deflection if you (rightly) ignore buckling, it just adds a DC offset to the stresses. That is, yes it it is a real world consideration but an unnecessary complication for this question. Incidentally although a spoked wheel seems relevant, a real bicycle wheel works in...
And yet China's coal use for electricity production still increases at just the same rate as ever. Rarely have I seen such gullible wholesale swallowing of a piece of spin. Post 132 in this thread for those with the attention span of a goldfish.
True we didn't work to code, correlation is the main game, although I did used to have to sign an actual official report that said , in essence, vehicle model xyz has been tested in accordance with procedure abc and it passed.
We used to do a regression analysis on each iteration of the app when it was released. This would run through a standard suite of models and we'd then check the results remained the same. Or not. Problem is it's a non production task, so nobody has time to do it, so we just carry on with the old...
As this makes clear, the skid unit (tractor terminolgy) holding the turbine/gearbox/rotor system is the strength member, the cabin is just an alloy tube for holding passengers.
