CRP-1 (or 5) v ARC-1 (or 2)

[MikeNE3]

Apologies if this topic has already been covered.

I am just starting to study for my PPL and was wondering whether anyone could tell me what the difference is between the CRP-1 and the AFE ARC-1.

Should I be looking to purchase the CRP-1 (or CRP-5) or the ARC-1 (or ARC-2)?

Cheers

[BackPacker]

For PPL, buy the cheapest flight computer you can get. They will all do the calculations required at the PPL level perfectly fine. Mine is the Jeppesen one made from cardboard and it's still serving me well four years after having gotten the license.

After your PPL, if you find you like (read: understand) the analog flight computer sufficiently well to keep on using it, and you use it regularly, you can always buy a metal one. But I also see a lot of pilots buy an electronic flight computer post-PPL, or use a flight computer that's integrated in their GPS, cellphone or PDA.

If you continue for a CPL/ATPL, well, by then you will know enough to make an informed choice between the four you mentioned.

[RTN11]

The differences aren't massive, they're more to do with layout than anything. The difference between CRP-1 and CRP-5 is the speeds you can calculate up to are much higher (i.e. for jets) and a couple of extra functions for commercial level.

I would try and pick the same computer as the instructor (if they use one) so then they can explain how to use it much easier than having to familiarise themselves with it first.

[Ultranomad]

I know some people here will disagree, but I personally believe the very best flight computer is your brain - at least if you are reasonably good with mental arithmetics and have some knowledge of trigonometry.

[BroomstickPilot]

CRP-1 & 5

Hi MikeNE3,

If you do not intend to 'go commercial/professional' then you definitely do not need a CRP-5, while this computer is essential for anybody doing CPL or ATPL.

The CRP-5 differs from the CRP-1 only in that it permits calculations involving Mach numbers etc, which are only of interest to those operating high performance aircraft at high altitude.

Using a CRP-5 for PPL work is a waste of money.

Regards,

Broomstick.

[worrab]

OK Anton_K - I'll ask. How do you account for wind/heading to PPL exam standard using mental arithmetic?

[Molesworth 1]

How do you account for wind/heading to PPL exam standard using mental arithmetic?

I doubt whether you could - although there are some clever rules of thumb out there.

Actual flying post-PPL is a different matter. If one doesn't have a GPS one tends to follow coast, railway lines and other ground features. VOR is also useful.

Mental arithmetic is really the only innate ability required in order to fly an aeroplane.

[Piper19]

If your teacher recommends a type stick with that. If he does not, get the cheapest. I've never used it after my PPL exams. I have the E6B algorithms on my laptop in a free software program, and also my Garmin GPS has these functions. As third backup I make my flight planning on a MS excell sheet, and all needed functions are preprogrammed. And in the end, I still do a lot of rough calculations by hand just because I can better see what is happening rather than just computer outputs.

I still have the CRP5 and it's the best I've seen, altough it just collects dust now.
NEVER buy the metal Jeppesen, that was my first one and the two metal disks were biting into each other. After a few months I was unable to rotate the disk by hand.

[Ultranomad]

Worrab, precisely this task on my PPL exam didn't take more than 20-30 seconds to do (in my head). Of course, I had four answers to choose from, so in actual operations it would take more to arrive at a (yet unknown) value - but not much more for the kind of precision you may need for a VFR flight, unless you are reeeally pushing some limits for your aircraft.

On second thoughts, for those who really need a flight computer or calculator, I'd wholeheartedly recommend the old Soviet aviator's sliderule, a.k.a. NL-10. It has lots more functions packed, and is an impressive conversation piece :-)

[BackPacker]

NL-10

The one picture I found on the internet suggests this is a linear sliderule instead of a circular. Nothing wrong with that of course for fuel/endurance/ETE calculations, but does it have a "wind side" as well?

Anyway, I'm still looking for a flight computer which includes the specific weight of Jet-A1, in addition to 100LL. Anyone?

[worrab]

Don't get me wrong, I'm not decrying mental arithmetic - far from it - but when faced with the requirement to produce a mathematically accurate PLOG without an electronic calculator or computer then slide rule or ARC look like good options.

[IO540]

How do you account for wind/heading to PPL exam standard using mental arithmetic?

If the PPL syllabus requires you to wear pink underpants then you have to do that. You can't do those calcs in your head because the CAA exam multiple choices are designed to pick out common errors in slide rule usage and some of the answers are very close together for that reason. It has no practical purpose because not even a robot (or a £20,000 autopilot) can fly a plane to that heading accuracy.

But practically, your drift is about half the wind, at c. 100kt. So, flying along in the average spamcan, if the crosswind component is about 20kt from the right, then you need to point about 10 degrees right.

How do you get the wind aloft? Form 214, or take the surface wind and add about 20/20.

At 150kt, the drift is about 1/3 of the wind.

These simple rules are about as accurate as the slide rule, given the typical errors on F214

[Ultranomad]

Originally Posted by BackPacker

NL-10
The one picture I found on the internet suggests this is a linear sliderule instead of a circular. Nothing wrong with that of course for fuel/endurance/ETE calculations, but does it have a "wind side" as well?

It does. It supports all the usual navigational problems, plus a few less common ones, plus some more for bombing, gunfire and photo reconaissance...

[Cusco]

Me thinks anton talketh through a hole in his ****

Assuming (not unreasonably) that the thread starter is doing his PPL in UK, the advice already given is kosher:-

CRP 1 for PPL only
CRP 5 for aspirations of greater commercial things.

(worth the extra for a wind arm IMHO)

Even then one could argue for starting with the CRP 1 and flogging it for the CRP 5 later.

Get the one your instructor recommends/uses.- It'll make teaching you easier.

You can leave the Russian stuff for bombing and gunfire for when you join the Russian military.

Cusco.

[Piper19]

haha, I've seen one like that russian one in a WW1 museum over here. My grandfather told me once they used the same thing in engineering school in times before electronic calculators were invented. In fact I once did learn to add, subtract, multiply and divide on the CRP5.