Fuel Reqs and TAS

[CaptPete]

Hello all, a few more questions. Thanks for your help so far!

A large turbojet aircraft in a commercial air service ona 2hour and 30minute VFR flight butns 2500lb/hour for cruise and hold, and 3600ib/hour in the climb. What is the minimum day VFR fuel requirement if the aircraft took 20mins to climb to flight planned altitude.
a)7850lbs
b)8465lbs
c)10,800lbs
d)12,150lbs

Anser is b, i got 9116.7 Anyone willing to verify?

Oh and one more, i promise!

The following information relates to a turbojet aircraft cruisng at FL300:
IAS: 267kts Indicated OAT -28C
Instrument and position error: +8kts Temperature rise: 20C
Compressibility error: -13kts
a)456kts
b) 477kts
c) 427kts
d) 433kts

Answer is A. I got this one right by chance i think. Anyone have a walk through?

Thanks again for the help!
Pete.

[trey kule]

Let me see. A large turbojet. Commercial Service. A 20 minute climb.....VFR?????

[CaptPete]

That threw me off a little bit too. But that's what the questions says. Ref is #99, page 4-29 of the aerocourse atpl workbook. I got 9116.7 which is 651.7lbs over the correct answer. Not sure what I'm doing wrong.

[mellow_pilot]

Wild guess? You're calculating for 45min reserve instead of 30?

[CaptPete]

Nah, had the right fuel reserve going. Though it would have helped if i took off the 20mins required for climb from the total trip time . Still only got me to 8283.2lbs, but at least it's closer to the correct answer. Any takes on the TAS question?

Pete

[trey kule]

Now I am feeling pretty sheepish about considering this a troll.

I did a quick calculation and got 7866# but I am not certain what the VFR reserve requirement for a commercial air service turbo jet is. I used thirty minutes, which is an IFR minimum based on fuel to an alternate..If it is 45 mins I would get the answer you said is correct.

[CaptPete]

hehe me a troll, nah, just trying to get some help for an upcoming written

7850lbs is straight up getting there, climb and 30mins day vfr reserve. we know night vfr reserve is 45mins. RAC 3.13.1 says nothing about holding fuel for vfr. then again neither does RAC 3.13.2 for IFR flight. I was taught in IFR to count for 10mins for a hold and 10mins for an approach when calculating fuel requirements. But even if doing so, i get 8283lbs. Something obvious isn't clicking maybe i missed something in the CAR. It's kind of sad i can't answer this kind of question at this stage.

Pete.

[trey kule]

Why would you carry additional fuel for a hold and an approach if you are flying VFR? This would fall under the category, of wind, route and all considerations, or as contingency. The information just stated the fuel burns for these types of situations which may be a red herring. My calculation was based on 2+30+30 reserve plus 366# additional for the climb portion. Maybe to somple.

The whole VFR thing boggles me as I dont know the answer. Never occured to me to take a 2 1/2 trip VFR in a turbojet. You might find some fuel requirements in the 700 series with regard to commercial turbojet heavies.

I am truely curious as to how the correct answer is calculated. Be sure to post it.

[CaptPete]

Why would you carry additional fuel for a hold and an approach if you are flying VFR?

you wouldn't. just trying out different combos to get me to 8465lbs. And a little further reading into the CARs and it's 45mins VFR reserves for a commercial ops. Oye. That still gives 8491.6 and not 8465, but alright.

[trey kule]

I get the same answer. Keep working on it.

[Foxtrot]

Help on your TAS question....

ICET

Works something like this....

You convert your indicated to calibrated

Then, use compressibility to get E (I think it's called elastic or something)

And from there, you use the rest of the info to get TAS

[CaptPete]

sweet, thanks!