Electronic flight computers

[Chocks Wahey]

Has anyone ever used one of these gadgets and if so what do people think of them? I am toying with the idea of buying one and would like to know what others think and which models, if any are recommended.

[PPPPP]

I bought a Jeppeson Techstar on eBay for a much reduced price, but after the first few days of playing with it realised that the "whizz-wheel" is actually quicker and accurate enough given the approximate nature of forecast winds. I now use the Techstar merely to check my manual calcs if I come up with an unlikely-looking figure for drift etc. Mind you I am old enough to have used a slide-rule in anger, so that might have something to do with it!

[IO540]

I think that the rule of thumb (max drift is half the wind, for a ~100kt aircraft) is as good as anything which can be calculated with either a calculator or the silly circular slide rule.

This is because form 214 data isn't accurate enough, and few people can fly a heading accurate enough for long enough.

[murphy1901]

I've got a CX-2 Pathfinder and think it's great!


Faster than "the wheel" and very easy and intuative to use.

[Airbedane]

Use your brain instead. It's the best electronic calculator of them all, it keeps your eyes out of the cockpit and even better, it's free!

Calculate max drift from the formula:

max drift = (Wind speed in knots)/(airspeed in nautical miles per minute)

Apply it by using the (analogue) clock code:

Calculate the number of degrees off track the wind is, look at the same number of minutes on a clock face and use that as a factor of the full clock face to work out the amount of drift to apply.

i.e 30 degrees off=30 minutes=1/2 the clock face, so use half the max drift.

40 degrees off is 2/3 the clock face, so multiply the max drift by 2/3.

Full example:

wind 260deg/35 knots
TAS: 90 kts
Track required 305 deg.

Max drift =35/1.5*=70/3= 23 degrees approx. (*if the sum is difficult, multiply it up until it isn't)

305 - 260 = 45 deg = 45 mins=3/4 of the clockface.

23 x 3/4 = approx 17deg

therefore heading is: 305 - 17 = 288 deg. (my whiz-wheel gave 289 deg, which can't be bad!)

With practice it can be done quickly, even in flight, and the method will be as accurate as a light aircraft can be flown.

Note that the method does fall down for angles from 60 deg upwards (all give a factor of 1), but it'll never be more than 10% or so wrong, or just a few degrees in practice.

[Sassenach]

Whizz wheels don't run out of batteries or get knackered when you drop them. They are very reliable and give surprisingly accurate answers. Once you've got the hang of them, they can be just as fast (if not faster) to use as an electronic widget. They also require you to use your brain, and you'll find that your mental arithmetic will improve when you've been using one for a while.

Why throw technology at a very simple problem that can be solved using a couple of bits of twiddly plastic?

[IO540]

Why throw a piece of twiddly plastic at a problem whose input data is so inaccurate, and whose output data cannot be utilised to its apparent accuracy (never mind its actual accuracy), when doing "max drift is half the wind" in your head is almost instant, and (unlike fiddling with the slide rule) can be done in the air?

If the silly WW1 slide rule was removed from PPL training, the hours saved could be used to teach useful navigation.

[S-Works]

And of course don't forget we can open the whole debate again about how a map and stopwatch along with the mental arithmetic are better for navigation than a GPS and radio aids....... :p

Personally I use a CX-2, cheap cheerfull and easy to use and in the air I use the half wind rule.

The Whizzy wheel should be confined to a glass case in a musium somewhere along with the slide rule.

The brainiacs in industry were quick to drop the slide rule in favour of the computer realising how it improved things, perhaps we should also move into the 21st century as well instead of keeping flying in the dark ages.

:}

[FlyingForFun]

Personally, I like the whiz-wheel. Use it all the time when I'm planning a ded-reckoned flight on the ground.

I'd never dream of using it in the air - mental arithmetic is perfectly good enough. Also wouldn't use it on a flight where I'm planning on using nav-aids (e.g. any flight in planned IMC) because the navaid will show your drift anyway. Bearing this in mind, I haven't ever seen the need to try out one of the electronic ones - I can't see the need.

Just my personal opinion, though. This is an area where there are no right or wrong answers.

FFF
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[Boing_737]

Brain and whizz-wheel are loads faster and way more accurate when the batteries are dead on the GPS and the calculator.:8

[Sassenach]

IO540 - try using "max drift is half the wind" in a 200kt aeroplane and you'll find it isn't accurate enough. Airbedane's formula is a better one to use.

A slide rule can calculate correct to three decimal places, so there's no issue with its actual accuracy. You should be able to fly a heading correct to plus or minus a degree or so. If you use an appropriate wind-correction technique, it will negate the inaccuracy of the wind forecast. If you get it right, you'll arrive directly overhead your destination.

This reminds me of the old story -

(NAVIGATOR) "Navigator to Pilot - turn right one degree."
(PILOT) "Sod off!"
(NAVIGATOR) "Navigator to Pilot - turn left four degrees."
(PILOT) "Left four degrees, Roger."

...short pause...

(NAVIGATOR) "Navigator to Pilot - turn right five degrees."
(PILOT) "Right five degrees, Roger"

[IO540]

Sassenach

Actually, in a 200kt plane the wind drift matters a lot less than in a 100kt plane :O I think you meant it the other way round, 200kt wind?

Also very few people here, never mind general PPLs, are flying at 200kt. Only very few piston planes can do a genuine 200kt, and most of those are turbo and need to be at FL200+ to get the TAS gain.

If you can fly a heading to 1 degree ACCURACY, you are a) a robot and b) flying a PC sim. Not even an autopilot can fly a heading to 1 degree STABILITY except in dead still air.

As for accuracy, a slaved HSI doesn't read that accurately, and even the most perfectly calibrated liquid compass cannot be read that accurately.

The only way to do 1 degree is to fly along a GPS track.

You must be pulling my leg.