RJ vs. TP in AirlineSim

English Boards General
1

Hi everyone,

There are like millions of threads, blog posts and studies all over the Internet regarding this matter. Just do a simple Google search and see for yourself.

In short, there are two main differences between regional jets and turboprops:

  • RJ is faster

  • TP burns less fuel per hour

On short flights (~350nm or ~60 minutes), TP’s slower speed is hardly noticeable, while fuel burn is significantly lower than RJ’s. I had a look at the performance tool for the ATR72-500 and Embraer 170 in AirlineSim and found out that this is nicely simulated, as expected.

On longer flights, TP’s slower speed becomes obvious. Furthermore, TP will spend more time in the air meaning that it will also burn more fuel than an RJ. I had a look at the performance tool for the ATR72-500 and Embraer 170 again and found out that this, however, is not simulated at all. ATR was still more fuel efficient than E-jet in AS.

So, I have two questions now:

@ASTeam: Is this issue going to be fixed in the next performance system you talk about (or anytime sooner/later) ?

@OperatorsOfRJsInAS: Why the hell do you use aircraft that have considerably higher acquisition, fuel, maintenance, staff (…) costs? Am I missing something here?

2

I don’t know why others use RJs. But I know that by using them I:

  1. get more flights per day out of one plane (assuming flights are more than 60 minutes) hence it may be more economical to employ RJs

  2. can fly routes not almost imposible with a turboprop to/from smaller demand airports.

  3. exploit the fact that, as in real life, in AS passengers prefer jets to turboprops and the financial sense using turboprops is not their concern.

3

I think you are underestimate cruise consumption difference heavily. Quick search gave me figures of ~1300kg/hour of cruise flight for CR2

and ~600kg/hour for ATR42, which is more, than 100% difference. Cruise speed, on the other hand, differs between them only around 40%.

So to get better on fuel consumption you need to cruise RJ for at least 2-3 hours, which give you "target" route length above 2000km.

If you check ATR42 vs CR2 in AS on a route over 2kkm you’ll get the results you are expecting.

4

But that’s more than 1000nm, still way too unrealistic.

5

Sorry if I didn’t state things clearer, but the consumption figures I posted

should be for RL plane, not AS simulation. I fail to see how

those can be "unrealistic".

6

Right, I thought you were using AS’ figures. Can you post the link where you found them?

7

Squirrel explained how he calcuated using fuel flow figures he found after a bit of research. Look at his post again :wink:

8

Yes, but I asked for the source of fuel burn figures. ;)

Maybe he could also post fuel burn figures for larger TP and RJ.

9

It was plain google, nothing special.

ATR 42 figures taken from this PDF for cargo version.

CRJ consumption were taken as "common knowledge" (i.e. unproven)

from airliners forum, although You can get similar figures from this manual.

10

Alright, thanks.

But it still puzzles me because all of the discussions on the Internet would end with a conclusion that RJs burn less fuel after around 350nm.

Maybe these smaller aircraft are exceptions, or otherwise what’s the catch?? Surely all those people can’t be wrong!

11

It’s not a new thing when “common knowledge” or majority opinion proved to be wrong.

I’d like to point, as observer of many such discussion on airliners.net forum, that people

often confuse fuel burn, CASM and overall operational cost, which may lead to believe

in superior economy of RJ.

I think most of RJ advancement during last two decades was possible due to passenger

preferences, not planes economics differences.

12

I am using the AVRO RJ with my Canadian airline Polar Fox Express for only one reason:

The Avro can carry more passengers to a small (RWY length less than 1800m) airport than a Dash 8. All other airports are served by 737 and CRJ…

13

Don’t forget fuel burn isn’t the only factor involved in operating costs. Greater utilization has been mentioned previously, but in reality this is reflected in fixed hourly operating costs (crew, maintenance etc…) obviously the break even distance varies based on aircraft type. Also passenger preference must be considered, passengers may accept the TP on a shorter flight, but on longer flights there’s a clear discrepancy between the TPs and RJs.

This is also a good opportunity for me to mention the Dash 8-400 in the game has inaccurate performance figures which I’ve mentioned repeatedly (cruise speed is actually 660kmh!)

14

Dear CaptAPJT,

I’ve recently done some research on the Q400 series, as we are working on the new performance system. I found out that typically, the cruise speed of 414mph / 667 kph is NOT reached by airlines in service, as this velocity is reached at 17000ft. The Q400 usually operates around 25-27000ft, where cruise speed is traded for economy.

If you have any data differing from what we dug up, please get back to me via PM :) . We’d be thankful!

15

Thanks,

Unfortunately your wrong, I fly the Q400 :wink: You’ll find the aircrafts max IAS is 285 achieved at around FL180, above this the aircraft becomes limited by mach number (0.6 due to the propellers entering trans-sconic range if set to max in an emergency descent). In any case this still gives, from 170-250 a TAS of 350. Highspeed cruise is used in normal operation as the fuel saved hardly offsets the extra fixed costs associated with reduced speed (Intermediate speed cruise saves 20% in fuel but adds 10% more time). As for FL270, this is only available on the Q400 with the option of drop down oxygen, as this generates more costs in terms or weight, installation etc. its not an option selected by most airlines as withou the aircraft is certified to FL250 so the extra 2000’ gives almost no benefit.

1 Like
16

That helps a lot, thank you! :) Can you cite any source for the velocity-matrix?

17

It’s from the Operations manual for the Dash 8

18

I can also tell you the reason for the limit of 245 below 80 is due to the windshield! It’s common with the Dash8-100-300 and only bird strike tested to 245.