Where do you use you calculator ?


I was impressed by the pictures of Geoff showing the use of his calculators in a Boeing 767.
So in which (un)usual places do you use you calculator(s)?

I use my trusty HP 48G + (or sometimes a HP 41 CV) to do some back-up calculations in the operating room. Most anesthesia machines can do their own calculations but sometimes it's easier or quicker to do it Yourself, and there comes the HP.

AW = Anesthesia Workstation, does the ventilation and cardiovascular calculations
HIS = Laptop connected to the Hospital Information System, gives us all patient data.
TCI = Target Controlled Infusion, delivers the main anesthetics to the patient. Automatically calculating the doses taking into account time, patient weight, and wanted concentration.

Ljad Belgium.


Cooooool! I know this is fishing for rpn porno, but since you say you actual sometimes use the 41CV, realy then there should exist a photo of it in this environment....


This is neat - I'd like to see more such uses.

You could also include the ratio of the value of the equipment with which the calculator is used to the value of the calculator! I don't know how much your anesthesiology equipment is worth, but I suspect the 767 wins on that account.

I suppose the 41s used in the Space SHuttle are the overall winner in this category - unless somebody uses one on a nuclear-powered aircraft carrier!


The simple answer is: everywhere. My trusty 50g doesn't leave my side.


at the telescope for coordinate conversions


Very nice responses!
Don't You have a photo showing the telescope and the calculator?

the ratio of the value of the equipment with which the calculator is used to the value of the calculator is also a very nice idea. The anesthesia workstation costs about 50.000 Dollars (which i didn't have to pay myself luckily!) So the ratio would be somewhere around 300 (not so high)

Ljad Belgium.




Howard, I would like to ask you more about it, but it may be off topic. Could you e-mail me? Thanks.


Another one here (my friend Antoine in DC-10 at 30000 ft running HP-41X on HP-48GX):


Thank you Hrast for kindly putting this picture here.

Since last summer, I have now flown the B757/B767 , on almost the same track as Geoff Quickfall ( see here ), but instead of flying hydroplanes earlier like you Geoff, I just flew over the seas on Aircraft Carrier jets.

... Geoff, I instantly recognized your B767 Cockpit ...

Besides of ASTRONAV, what do I use HP41X/Y/Z for ?

Very simply for 2 main computations :

1 - When you take off on a JET A/C, most often, your actual Payload, Fuel Onboard and therefore Take Off Weight / Zero Fuel Weight are somewhat different from the ones printed on your Operational Flight Plan ( JEPPESEN " JETPLAN " for example ). Not so long ago when I was flying DC10-30 Cargo, we had up to +/- 30 tons on Take Off Weight " last hour " change, with no possibility to receive an updated JETPLAN. Obviously, we corrected Fuel uploads accordingly, but - as regards fuelchecks airborne - we were left then with 2 OPTIONS.

* Either use our initial and uncorrected JETPLANS, and compare the variation of the fuel differences during the flight : we could very well start up after level off with actual fuel figures of + 8 tons when compared to printed figures. And then over the elapsing hours, this difference should modify slowly ... this was a first way of monitoring our fuel consumption.

** OR - my favorite solution thanks to HP41X/Y/Z made by HrastProgrammer - and through the correct use of some Aerodynamical Formulae, from our printed "not updated" JETPLAN printed data I could instantly and very accurately re-calculate our fuel figures pertaining to the exact conditions of our actual flight. Then, if I observed " + 6 tons " ( compared to a non-updated JETPLAN ) in our fuel figures, I could then instantly compare this figure to the much more realistic values recomputed from printed JETPLAN data thanks to my software. This is a safer approach as regards fuel monitoring since – especially in case of big differences in Actual Take Off Data vs Printed ones – you EXACTLY know EARLY IN THE FLIGHT where your fuel figures stand, instead of having to wait over hours like in the first case.

By the way, Geoff, if you already have HP41X/Y/Z , I will freely send you my own A/C Fuel Monitoring Software for your own use. And if you don’t ... then you know what next step is :-))

2 nd Computation : Back to ASTRONAV this time. I use HP41X/Y/Z for Celestial bodies identification.

As a recent real world example, from my B 757 Cockpit at position N 23°38'2 E 039°22'9 on Nov 24, 2007 at 16h23 UT, I observed an unidentified Star at an approximate Height of 8° and and approximate Azimut of 165°. Which was this Star ??? IDENT gives the following results : S.H.A. = 344.589 DMX R.A. = 1.00043 H.MS DEC. =-55.07582 D.MS . I could then easily identify this Star as the Beautiful ACHERNAR .... :-))


Thank you again Hrast for your such wonderful HP41X/Y/Z Software which for me runs perfectly on HP48GX.

Antoine ( from JEDDAH Saudi Arabia to-day ... )


2 nd Computation : Back to ASTRONAV this time. I use HP41X/Y/Z for Celestial bodies identification.

Alternatively, you could take Astronomy 101.

Dave (retired radio astronomer and astronomy/physics professor!)

PS actually, real astronomers are often the worst ones to ask "What star is that?" We spend most of our observing time at the telescope computer console (both radio and optical telescopes these days), pointing at some set of coordinates - not outside enjoying the actual sky!!


I... use my 50g for quick calculations at home and work (which is as a "Computer Technician." I'm the company IT guy, basically.)

I know it's overkill, but I wanted RPL instead of RPN, and 48s were going for too much money, and if I were getting a new calc, might as well get a 50g instead of a 48gII.


Sometimes I take it into the lavatory stall and use it to help me
memorize numeric squares while I'm doing my other business there.


I broke in my HP35s with some 'napkin calculations' while working on the SpaceShipTwo flight-test vehicle earlier this year (yes, as in Burt Rutan, X-Prize, etc). The HP35s rested on aft-fuselage panels while I crawled around on my knees making trim markings for the shop folk.

Currently, I'm conducting research at NASA Langley Research Center and pursuing a M.S. Eng in aerospace, where I'm using laser moire interferometry equipment (~$1M) to investigate strain levels in adhesively-bonded structural joints. I have lost my 35s (probably during our relocation), and am using a 49g and a 48g.

No can do on pictures in the first case. The NASA work will be published early in 08, so "more to come" as Carson would say.

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