Recap

Thanks for the connection Bob. Times sure have changed, uh?
Ed

 

Bob- You are so right. When I had to do Airplane Design in college and then my first job at Douglas Aircraft in Missiles and Space, all my calculations were done on a slide rule. Our group felt lucky when we finally got one Friden Calculator for all of us to use. Then the Bendix G-15. By calculating your own numbers, or in your case drawing full size, one got a since of feel for a design. As more computers came into existence, and I went up in rank, if you asked an "old" engineer what would happen if I changed a parameter 5%, he could give a pretty accurate reply on the spot......a new young engineer out of college would have to go back to a computer to give an answer.

 

I have been a software analyst for the last year and a half since I left the car bizz.

A couple of weeks ago I got pissed off at our development department and wrote them the following e-mail because they kept offering crap excuses about why they could not or would not do a crucial programming task that we needed.........basically it said.......

"Over 50 years ago when something really, really, mattered, a person with a piece of paper, a pencil, and a slide rule was able to figure out how to send a 5,000 pound bucket of instant sunshine 9,000 KM thru space against the rotation of the earth's orbit and have it land within a 200 metre CEP of the center of the Kremlin........and you are telling me that you cannot program _ _ _ when you are dealing with the oldest software company out there (our competitor) and we have been pulling data from their site for 25 years ???"

It quietly got done 2 days later.

 

Bob, you sound like my Dad, (Bristol Aeroplane Co. Brabazon-Concorde), carried his slide rule till the day he died...always told me it was quicker than my electronic gadgets..

 

^^^^^ 1000%

The computer has taken away intuitive engineering sense developed through exposure to physical testing and hands-on product development.

 

Sounds like the gathering of friends my Dad would have over when I was a kid, didn't matter if it was Aero engineers, or by that time Cosworth, Ford, Lotus or others from F1, I could sit there for hours and listen to them "fix the mechanical world" .
Funny thing is my dad was the least "practical" guy you ever met. I would take him hours to get the lawn mower started.
On of the funniest stories I tell about him, was when I was a kid my allowance was based on mowing the lawns. We had this huge mower that used to belong to parks and recreations dept. So one winter Dad strips it down to give it a full overhaul, well spring is rolling around , grass is getting tall and I'm out of cash. Mum and Dad are away for the day, so I rebuild the mower (I was maybe 12-13) and cut the lawns (about 3 acres), clean everything up and put it away. All good right ? Wrong.. Dad comes home and rips me a new one, what did I think I was doing, did I know how dangerous I had been etc etc...lesson learned for sure.
Only many many years later while having a pint with old fella did the truth come out, he wasn't so mad about me cutting the grass, it was the fact that he had been trying to put the thing back together for nearly 2 months and couldn't get it right.. and his 12 year old kid just went ahead and put it together like lego...LOL

If he was hanging a picture and couldn't get it straight he would design and new hammer and nail...

 

Bob- Pickett for me, too, in college. AF had HP40s and HP90s by the time I was a senior captain, but most flight planning was done with a whiz wheel (circular slide rule) for quite a while. The HPs were used to convert coordinates to offset range and bearings for the analog computers in F-111As and F-111Es and to convert UTMs to lat/long.

Engineering is different now, but it is amazing how quickly solutions come out of the latest tools. Unfortunately now it usually takes one person to run the model and another, bigger picture guy, to interpret the results and tell whether they make sense. Everything was by engineering rules of thumb in the olden days, developed through decades of experience. Not so much today.

 

When I was in chemistry, we were not allowed to use calculators even though the first HP's were out. Later, I was ready for circular whiz wheels in the F4 and on my Breitling.
It also really gives one a feel for logarithmic relationships.

 

I'm a principal in a small gas turbine engineering firm. We only employ engineers with 20 or more years of experience (and actually most of them have closer to 30, truth be told). That sounds cruel, but our guys know turbines inside and out. We seldom go down "dead ends", or have to do more than one or two iterations to get the design of any component right. All of our guys have "been there and done that" more than times than you can count. And yes, we have to pay a lot more for that experience, but it's far less expensive than putting a youngster on the clock and letting them try to figure out the problem and him taking three or four tries to get it right, and then take the risk of turning that into hardware that may or may not work.

Good engineers, as noted above get what I call a "feel for the numbers" and they can "see and feel" what is right and wrong, long before the computer spits out it's results. Lot's of times we'll look at a design aero problem and some guys can "visualize" what the flow is going to do, long before the CFD analysis spits out the plots. They've done it enough and seen it all before, and they know if the Mach number is here and the flow distribution is such, it's going to take this distance to mix out, and unless you do such and such you are going to have a problem.

You could run hundreds of CFD runs or do tons of finite element structural analysis and eventually plow through the problem and get it right, or you can get someone who knows what it will take to get it right, do one or two iterations and be done with it, and close the books on it. There is a fundamental difference in this approach. That is, the engineer isn't using the high powered CFD and finite element structural analysis as a basic too. He uses some spreadsheet analysis, his experience and his eye, to accomplish what the basic design needs to do, does some additional analysis and some quick hand calcs, and then models it up, safe in the knowledge that the average stress or average Mach numbers are where he expects them to be, and he can then fine tune the design with the high powered tools.

You simply can't imagine how much easier it is to do it that way, and it's far less expensive since you aren't doing countless iterations before you finally get it right. Less experienced and a lot of younger engineers haven't been taught to think this way, and want to do everything "on the computer", and doing it that way they never get that "feel for the numbers" and never get to that higher plane of understanding.