Looking for the first Field Engineering HP RPN model 15C


I had used the 15C with either hand without a desk, you can't do that with the 32SII. When will a field calculator be made? One loaded with conversions (my memory is lacking and the pamphlet in the pocket tears and fades), register memory, basic integrals and derivatives simply a semi-NON-programmable model. One with trig, ln, e, pi, i, factorial, the 32SII is semi-close but it's oriented vertically instead of horizontally - and is "tapered" seems the 15c shape was ideal, if not why continue to make a 12C. I can only assume mankind doesn't want to consider: "in the field engineering" What is the modulus of elasticity or thermal growth of whatever... or natural frequency, BTU's, horsepower, joules, blah, blah, blah...... I can only guess HP has had more than one email about it's good old 15C that just didn't have enough customers. What do these antiques retail for on eBay, $180 to $300 ? And they still don't know what 9.8x10E-6 is, so you have to memorize it along with 300 other tidbits, so can you say on the spot if it will hold or break, should you evacuate or stay? I don't know let me go back to the office and program it. Better yet let me use a colloquial equals sign to slow down repetition in the field.


The designs I have created for OpenRPN are all highly rugged but are constrained to fitting in a shirt pocket. I'm open to making an optional ultra rugged accessory kit (perhaps a more hefty protective boot for example). If you have suggestions or requests I'd love to hear them.

The stock enclosures will feature a rigid core containing all the electronics surrounded by a 0.125" thick black neoprene boot. It will be bordering on overkill for normal usage, but field workers will undoubtedly want more protection.

Either post to this thread or send me an e-mail.

Best Regards,



I'm very sorry, but eventually you are going to have to face reality. OpenRPN, like QonoS, is Vaporware . The difference is Hydrix had cash and managed to produce prototypes - something openRPN has not yet done.

Edited: 28 Dec 2005, 6:37 a.m.


Bad troll! No cookie!


The difference is Hydrix had cash and managed to produce prototypes -
something openRPN has not yet done.

There's another interesting difference between the two projects. OpenRPN seems thus far to be focusing on developing a cost-effective manufacturing plan (for relatively low volumes without needing a very large investment in tooling), and hasn't yet developed electronics or software.

The Quonos from Hydrix had working electronics and software, but no cost-effective manufacturing plan.

In my not-so-humble opinion, developing the electronics and software is EASY compared to the manufacturing issues. If OpenRPN can successfully tackle the latter, the rest will be a cakewalk.


Yes. Make it the exact same shape and size as the 12C or 15C. Put a large enter button in the middle like the 15C or 12C. Make the screen exactly like the 12C or 15C perhaps a few decimals longer (easier said than done), maintain all the basic primary button functions like on the 32SII, and majority of secondary functions but, Get rid of the programming ability (aside from complex mode ability), supplant the programming with a library of constants i.e. thermal capacity of sand, thermal growth of steel, stainless, aluminum, copper, glass, yield stresses of steel, stainless, aluminum, density of steel, water, aluminum, concrete, granite, polyethylene, conduction of wood, asbestos, brick, concrete, water, max solar radiation, heat of vaporization of water, of course I know all these things and then on a Tuesday or Thursday I forget one of them! You could display: k sand = 0.44 btu/hr-ft-F (alpha numeric library seems simple enough) Or and I never said this: provide the alphabet "on the keys" to allow us to type in our own. (No external methods please, no extra devices). In this way I'll only have to memorize applicable equations. And I'd say an 1/8 inch protective skin like an iPod would have been fine for the old 15C but, why talk of extraneous things like skin what happened to physical function, look at how your hand grips an object - why is it fact that a calculator laid out horizontally is better than vertical (and now watch everyone say, hum is that right?). The key is simplify. I don't just mean to mention construction, consider canvasing the engine testing world 26,000 rpm mil displacement or production line equipment monitoring decision making "constants" ... When do you apply MC/I or even simpler sigma = F/A or Thrust = PxA but, I can graph y=x**2 + 5 I've said enough, good luck with an on-the-spot engineering calculator.


Nostradamus wrote:

Get rid of the programming ability (aside from complex mode ability), supplant the programming with a library of constants

You must be kidding? There are numerous programs that can apply to 'in the field' work.

If you expect us to respond to your points, please format your statements. You jump around quite alot, and it places the burden on us to extract your intent.

Nixing programmability for more storage space is unecessary. How many megs of text do you anticipate you will need? Perhaps you would find a PDA w/ Excel more suitable. I have created some nice reference files on my PocketPC.



Perhaps "don't require programming for this laundry list of functions" is a compromise that would work? Or maybe "make the machine easy to use for the non-programmer" would be closer?

With today's memory capacities, I don't think you seriously have to trade off the capability of programming with, say, an extensive library of constants. But you could embed programmability to such a degree that the real utility of the machine would only be accessible through programming. I think that ought to be avoided, but I don't think programmability should be jettisoned.



I don't program in the field. What I need is a simple small calculator that is loaded with conversions and constants and functions - simply no need for programming - so why have it in a simple field tool.

Perhaps it should be titled a fast reference field calculator.


Got it. And if folks like you were the only customers, then I would expect OpenRPN to deliver a product more or less in line with your specifications. But I doubt they'll rip out the programmability just to exactly hit your tarets. But there are a couple of points that may not be obvious about that.

  1. Ripping out the programming probably won't reduce the price of whatever OpenRPN delivers, like it might if it were HP or TI doing the machine. A lot of the software engineering is probably going to be volunteer work.
  2. That also means the software will reflect the interests of the volunteers. (And they are all programmers!)
  3. You could benefit from someone else's programming, even if you didn't do any yourself. Perhaps the presentation of the constants would end up not being ideal for you, and a small amount of programming would make a difference.
  4. Programmibility shouldn't get in the way of operation of the calculator in normal, non-automated modes.

In an ideal world, your input on how you use a machine should have influence in a community focused project like OpenRPN. I wouldn't expect them to drop the programming, but your overall requirements sound like they could make a heck of a good "use case" in a system design effort. I think it would be useful for them to hear that you don't want a programmable. It should make them think how to ensure the regular operation of the machine doesn't get bogged down in bells and whistles. You should wander over there and put in your 2 cents.



@ Nostradamus:

Please take a look to this link.

Therein please take the post of Oct.14th to start with, giving you a comprehensive user interface proposal to look at. You'll see plenty of space reserved for CONSTants and CONVersions already as you requested. And you will have the comfort of a typewriter-style keyboard in this model. The keyboard was developed furtheron with the basic concept kept (follow the thread). If you see a need for more functions than incorporated there please tell me.

Besides, I agree with ECL: *some* formatting would be beneficial in your post. And I would keep the programming capabilities, too: you might come to like them later - and they don't limit you in the beginning.

Edited: 29 Dec 2005, 4:43 a.m.

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