Friday Night Trivia Smart Minds Required

[ksa5223]

So,

1. Flight Computer, dH 10,000 (175IAS = 203TAS)

Air Specific Range is not Ground Specific Range so we should not deduct the headwind and should use the TAS

20usg x 2.72 = 54.4kg

54.4 divided by 203 = .27kg/nm


The answer is not given by the examiner, so I am confused.

Why did they mark me wrong?

[Jabawocky]

Mental maths only here.......I think its the 0.31......

Try asking someone who knows though!

J

[ForkTailedDrKiller]

An aircraft cruising at 10000ft density height in a 20 kt headwind has an indicated airspeed of 175 kts

I guess its a Bonanza, huh!

Dr

[OZBUSDRIVER]

ksa5223, I had to go back to make sure.

SPECIFIC AIR RANGE = FF/TAS kg/nm

So , as far as I can tell, your calcs are correct.

0.27kg/nm

Specific Ground Range takes into account W/V
using GS of 183kts gives and SGR of 0.2972kg/nm closer to 0.29 than 0.31.

What does your KDR say? Using your figures, I would take it up with your flight test ATO on the day and see what they say.

[Icarus53]

Question doesn't specify AVGAS or AVTUR. I assume the 2.72 factor you're using is USG to KG of AVGAS?

I can't remember all the numbers but using 3.8 USG/Ltr and 0.81 kg/Ltr (AVTUR) I get a conversion closer to 3, resulting in an answer closer to 0.31kg/nm.

Can't tell you how many KDRs I've had from answers that could not possibly have been wrong, but don't bother taking it up with them as I;ve never had a response. You'd like to think you get what you pay for!

[alexthepilot]

ye if it's an ATPL examination then im guessing the conversion will be different, and thus what he said above

[ksa5223]

ozbusdriver

thanks oz

yes it is a cpl level question and it's avgas.

I think i am correct and it may well be a database error as its an online marking website :-)

[Kenneth]

And therin lies the problem with the current system..... minnimal feedback (KDR) and your left guessing why you got it wrong (if in fact you did get it wrong).