Admittedly, there are a few things that a slide rule can do well; for example, such as solving Ohm's Law problems. But for many problems in the aeronautical engineering discipline the slide rule is essentially useless. If you don't believe me try doing the Mach Number solution with your slide rule.
A slide rule to conquer the moon revisited


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06182013, 04:51 PM
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06182013, 05:50 PM
A slide rule is far better than a calculator for helping you draw straight lines however :)
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06182013, 08:20 PM
That's about all I've done with mine for the last twenty years! Use the slide, and you even have the equivalent of a beveled edge that won't suck ink back under the ruler. ▼
06212013, 10:15 AM
Quote:You won't find beveled edges on the loglog devices. Many of the older Mannheim slide rules not only have beveled edges but also include centimeter or inch scales on the edges.
06182013, 09:08 PM
Quote: I used to *love* to work that Mach number sample problem in some of the old HP manuals. I always thought it was the RPN equivalent of the aria from "Carmen" :)
Edited: 18 June 2013, 9:08 p.m. ▼
06182013, 10:57 PM
Quote: Me too! ▼
06182013, 11:08 PM
To all: Actually, a pencil, some patience, and an RPN mindset, along with a loglog sliderule, could solve this formula handily to a few decimal places. Note the "RPN Mindset". This is the greatest advantage the "HP Way" of calculation gives the operator. Sorely lacking in the "Algebraic/Textbook" world. My $0.02. John Stark PS: Looking forward with great anticipation to the "Prime". May finally give up my 45 and 80 for this beast.
06192013, 06:32 AM
Result with HP15C LE: 0,835724536 (in 1 minute, due to typing error, repeated in 30 seconds)
So error of slide rule is 2.67% with simplification and 9,27*10^4 w/o simplification, the time advantage for the HP15C is factor 7.5 Anyway, the slide rule seems to be accurate to three digits even for this lengthy formula. Otherwise, I think, the SR71 (note the pun) might have never flown.
06192013, 08:34 AM
There is something to be said for tackling this calculation with a language using a uniform operator precedence. Here it is rendered in LISP style prefix notation: (sqrt (* 5 ( (expt (+ (* ( (expt (+ 1 (* 0.2 (expt (/ 350 661.5) 2))) 3.5) 1) (expt ( 1 (* (* 6.875 (expt 10 6)) 25500)) 5.2656)) 1) 0.286) 1))) ;Value: 0.8357245351752515 Nick
Edited: 19 June 2013, 8:36 a.m.
06212013, 04:08 PM
Result on the wp34s, following the keystrokes sequence in the HP67 manual: 0.8357245351752513232390389024784470The last two digits should be 61, according to WA. Of course these so many digits don't make any sense, since the speed of sound at sea level in knots is given to only four significant digits (also, it's not known to more than the ten the HP67 can handle).
06302013, 05:57 PM
Hello all.
This also, is one of my favourite formulas to work through and demonstrate RPN efficiency. I'm wondering though, as in every manual, the coefficients and variables are already there but, it its generic form, which are the variables and which are the constant coefficients? Are the only variables 350 (CAS) and 25,500 (PALT)? Edited: 30 June 2013, 5:58 p.m.
06192013, 03:05 PM
In the current context, this old thread is interesting to read. http://www.hpmuseum.org/cgisys/cgiwrap/hpmuseum/archv013.cgi?read=43770 