CRP5 Questions
 

- Working out true altitude is not a problem, and more useful I think- but this has me confused.....any help would be appreciated.
(You are given pressure alt. or true alt. a QNH and SAT)

CRP5 IS SHORT FOR CRAP 5. JUST DONE THE JAA EXAMS MYSELF ANSWERS ARE NOT VERY ACCURATE WHEN USING THE '5' SO WE WERE TOLD TO JUST TO USE ISA DEVIATION MULTIPLYED BY 120.
FOR TRUE ALT CALCS TRY USING ISA DEVIATION MULTIPLY BY 4 {CONSTANT) THEN MULTIPLY BY HEIGHT IN THOUSANDS.
E.G -5 MULTIPLY BY 4 MULTIPLY BY 12(12000)
GIVES A MUCH MORE ACCURATE ANSWER AND ALL OUR CHAPS ARE PASSING NAV SO GIVE IT A GO.

CRP5
 

if anyone has a secondhand(in good nick) crp5 computer that they would like to sell at a good price, please email me...
cheers

Ummm, the bosses here don't like these kind of posts unfortunately.

But anyway, I've sent you an e-mail regarding this :D

Have fun training.

CRP5 What the *!*! is all that about
 

Help me out guys/gals

This is my first post. I am a PPL student. 30 odd hours, just really embarking upon Navigation.

Did your instructors really explain the Nav computer to you?? Mine has not, and frankly I am finding it highly confusing!

Does anyone have any hints and tips to get me on the right track? How did you become accomplished with your CRP5?

Thanks

h'mm i must admit i didn't completely understand the beast until i met gen nav in the ATPL's. And worked my way through the monkey see, monkey do chapters in the oxford notes

Which bit do you have problems with?

Is it the wind triangles or the slide rule bit on the other side?

MJ

No, my instructors didn't go out of their way to explain how to use the nav computer. But I found it relatively straight forwards just by following the instructions in the booklet that came with it. The AFE/J. Pratt PPL syllabus books have further instructions on the basics in them.

The main thing seems to be practise. The more you use it, the better you get at using it. The other thing that still takes me a while is doing the rough calculations that give you an idea of the scale of the answer that you are expecting.

I guess it seems anachronistic in this day of 'real' <img src="wink.gif" border="0"> computers to have to use a ciruclar slide rule, but as others will point out, the batteries can never fail in a CRP-5. But on the other hand, a real computer will tell you the answer without having to pre-calculate a rough answer!

I assume you are having trouble with the slide rule bit and not the wind calcultions. If you are having trouble with the wind calculations, make sure you understand the theory behind what you are trying to acheive and then just practise, practise, practise.

[ 07 January 2002: Message edited by: tacpot ]</p>

[quote]...a real computer will tell you the answer without having to pre-calculate a rough answer! <hr></blockquote>

Not true! Electronic computing devices are not infallible. Apart from failures of the device there is also the 'garbage in - garbage out' problem.

Unless you have some idea of what the answer should be, how will you know when the electronic brain gets it wrong? And it will get it wrong.

As for using a circular slide rule, only practice will enable the user to become adept. I find some problems can be solved quicker using a whiz wheel than a calculator.

If one type of whiz wheel is awkward, try using a different type eg from the 'slide' type to a 'CR' circular type. The CR5 from Jeppessen is my favourite.

[ 08 January 2002: Message edited by: Tinstaafl ]</p>

Backon

If you have any specific queries feel free to email me. It is hard to teach the whole thing remotely by internet! I am a ground instructor, formerly of General Nav for the now dormant SFT. Alternatively if you're near Bournemouth anytime soon I am happy to teach you the rapid and accurate use of this wonderful and powerful calculating device, in exchange for a couple of pints.

And Tacpot, if you're well-taught then you should have a rough answer in your head already! :)

I was taught how to use the !!!!ty-Five by Mr. Send Clowns, and confirm that it ayn't hard to use once you've been shown how properly.

Hot Tip alluded to already: take an educated guess as to the answer BEFORE you pick up yer CRP-5, that way you'll know immediately if final answer you get is bollocks or not.

[ 08 January 2002: Message edited by: Blackshirt ]</p>

I seem to remember that reading the Trevor Thom book on Navigation or Flight Planning, I forget which, was what finally got me to understand it.

I'd dig the books out to find out exactly which book it was (and it wasnn't some other book completely!) but my bookshelf is half way across the world at the moment, so apologies if I'm wrong and there's nothing helpful in Thom!

FFF
---------

Backontrack,

Basically, there are 4 types of operation that the CRP5 does for you.

1. Multiplication and Division and Conversions, just like any slide rule. I agree, for these, you are probably better off with an electronic calculator.

2. Distance, Speed and Time (and fuel-flow calculations). You can do these with a calculator, but it's actually quicker with a CRP5, once you get good at it. With a question like "You are doing 220 knots groundspeed, so how long will it take you to cover 57 nautical miles?", if you use a calculator, you get the answer in hours. You then need to multiply it by 60. By the time you've done that, you could have already had the answer on the CRP5, in terms of minutes, which is what you want, not hours. On the other hand, if the question is "Your groundspeed is 320 knots, so how far will you travel in 13 minutes?", then you need to divide, not multiply, by 60. With a calculator, decisions as to which way round to do the calculation, and slight loss of speed. No such problem with the CRP5. With that big black triangle on the inner scale, you work in base 60. It gives you the answer in the form you need it.

3 TAS and Altitude Calculations. To calculate these by numerical methods on an electronic calculator requires specialist formulae, which are too complicated for everyday use - especially TAS from FL and temp, and Compressibility correction. The CRP5 solves them simply and accurately.

4 Wind Calculations - the relationship between Heading, Track, Drift, TAS, and Groundspeed. These are vector problems and would be too complicated on a normal programmable scientific calculator. You have been able to get specialist aviation calculators with the formulae already programmed for years, but these have never really caught on because the presentation on the CRP5 wind face, as well as solving the numerical problem, gives you an instant intuitive picture as to whether the wind is giving you mainly head/tailwind component or mainly crosswind, and a visual picture of whether it's head or tail and which direction the drift is in.

Three other observations:

Firstly, if your instructor hasn't explained it to you, he's not doing his job properly. Ask him. You may find he doesn't know it himself.

Secondly, the little book that comes with the CRP5 is excellent! You can use it to teach yourself very easily, if you want to.

Finally, the Oxford/Pooley CRP5 Computer Based Training (CBT) CDROM will be available in February. You can get it from Pooley's. It is so clear in its explanation. In the meantime, if you want to, you can get the CRP1 CBT CDROM. It's pretty similar to the CRP5, but without the same number of facilities.

All the best,

Paul

[ 08 January 2002: Message edited by: Paul Hickley, Gen Nav Spec, Oxford ]

[ 08 January 2002: Message edited by: Paul Hickley, Gen Nav Spec, Oxford ]

[ 08 January 2002: Message edited by: Paul Hickley, Gen Nav Spec, Oxford ]</p>

I was under the impression we are not allowed to use calculators in the JAR Eaxma (PPL/ATPL)

Is this correct???

My instructor explained a little bit, but i got most of my info from the handbook that you get with it and also from the Jeremy Pratt Nav book!!

You can take your CRP-5 or simillar into any exam in any subject. You can also take a non programmable calculator too.

Only way to master the whizz wheel is to use it every day. U have too be damn fast in the atpl nav exam cos time is tight.

AS paul said the wee book is escellent

Well that just rips it!!!!! <img src="mad.gif" border="0"> <img src="mad.gif" border="0"> <img src="mad.gif" border="0">


My flying school told me i wasnt allowed a calculator for the nav exam!! I had to do all my working out on my wizz wheel!

Still passed though!

:) <img src="wink.gif" border="0"> <img src="cool.gif" border="0"> :)

The Trevor Thom Navigation book explains the CRP in great detail and is very understandable.
Also as Paul says, the little book which comes with the CRP-5 is also worth working through.
Also as previously stated in another post the Oxford General Nav ATPL notes go through the CRP-5 in great detail but its probably overkill to buy these if you are 30 hours into PPL.
Good luck

Paul may correct me if I'm wrong, but no electronic calculator is permitted in any of the PPL exams. The CAA has always been concerned by the slack control of exam sittings shown by some small flying schools/clubs, so maybe that is why some have been allowed. Non-programmable electronic calculators (not electronic flight computers!) are however permitted in all CPL/ATPL exams.

Thanks to everyone for their replies. It helps knowing your no the only ones struggling sometinmes.

I shall attack the Nav book and give it another go.......just hit a brick wall I think.

cheers

Backontrack,

Some Instructors teach the "wind up" method of using the whizzwheel and some teach the "wind down" method; if you intend to progress to CPL/ATPL, start using the appropriate method from the outset. I was taught one for the PPL and had great difficulty getting to grips with the other for the ATPLs.

[ 08 January 2002: Message edited by: Tee ]</p>

Tee,

Couldn't agree more!!!!!!!

'Wind up' is suitable only for PPLs, because they won't have to wind find or work out track from heading. But if you're going to be a professional you must use 'wind down'. It's the only way that's compatible with 'heading from track', 'track from heading', and 'wind-finding'. PPLs only have to do the first. However, if you want to pass these pesky JAA ATPL exams you have to be able to do all three. You have to do it 'wind down'.

Sorry about all the bold face. I don't shout in my lessons - well, not often, anyway. But the point is important.

All the best,

Paul

[ 08 January 2002: Message edited by: Paul Hickley, Gen Nav Spec, Oxford ]</p>