Might try researching Urethane. It comes in all kinds of hardness levels from hard to really soft. I even found a website that sells urethane springs.
http://www.centuryspring.com/products/urethane.php
With a 7 inch OD and 6.9 ID one could probably smash it into a ball and have it return to...
Tunalever, I think what Sibeen is saying is that if a firm is making $140/hour and paying a person $100 per hour they will be loosing money rapidly. An income of $40/hour off one person sounds good until you take in to account taxes, benefits, overhead, etc. and realize that it is costing...
... "Technology University have shown that the typical helical spring lock washer exhibits a spring rate after flattening which is approximately 70% more effective than a flat washer of the same thickness". ...
So how effective is a "helical spring lock washer" that is 70% more effective then...
I wouldn't call the spitfire slow and lumbering. Maybe slow compared to modern fighters (F-18, F-22).
I don't think having an engine that last only 1 hour would be usefull. Even if you rebuild it after each flight. You then have 3 guys flying planes and 30 guys rebuilding/replacing engines...
You might start with a motor and vary unbalanced weight and frequency (change RPM using speed controller) until you get a vibration that will wake you up. Its probably easier just to cheat (like Tmoose suggested) but maybe you can make it better...
Then you have the "ideal" frequency and...
MathCAD is the best software since Pro/E!!!
I did all my homework in college using MathCAD. It's like a word document that does math and is very easy to input equations, make graphs, solve complexe equations, track units, and etc. All you have to do is type and a document appears complete...
Probably enough technical info so I'm going to not be technical.
I remember when I first heard that firction was independant of contact area, I couldn't believe it. I grew up around cars and I know that bigger tires = more traction.
Then I came to the realization (or I made it up to help...
Have you tried adding a little lubricant??
Has made a world of difference for me when trying to press fit parts. Water may even work and won't leave any oily/greasy residue. A soap also works good, I used to use windex to get wake boarding boots on and the water kind of rinses away the windex...
