Simviation Forums

Hey everybody.

Rafiki,

There are no simple answers to your question. Let me try to explain what I mean by that.

The best way to increase the ceiling altitude from 30,000 to 45,000 is to redesign the aircraft with a much longer wing span, lower gross weight and a substantial increase in the thrust of the engines.

We can fake this by changing some numbers in the aircraft.cfg file, but there will usually be unintended consequences. Under the category of (flight_tuning), put in a value for cruise_lift_scalar of 2.0 or higher. In the category of (TurbineEngineData), double the value for static_thrust. These are just starting points.

Now, fly the CRJ and see how much the ceiling and speed have improved. After that, try an approach and landing at your favorite airport. Chances are that the above changes will cause a nose-down attitude during approach and possibly a higher setting for idle thrust. In other words, we've improved one problem area and messed up another phase of flight. In short, that is the risk of "tweaking" the flight dynamics. I know; I've messed them up more than once.

Back to the original problem. My search for CRJ-200 specs tells me that the ceiling altitude is 41,000 feet and the high-speed cruise is Mach 0.81. I'm sure the ceiling spec is for the aircraft at a low-fuel condition. If you're trying to fly to a very high altitude after a max gross weight takeoff, it just might not be possible.

Let me know if I've interpreted your question correctly, and sorry if the above sounds like a lecture. All of us want to make our favorite aircraft fly "right". I'm just trying to point out that it usually isn't as easy as tweaking a few numbers.

Regards,
JerryH

Thanks for the info,  With a higher lift scalar, will i not float above the runway on landing?  My main goal was to make a CRJ-200 a nice private jet that is fast, high flying, and of course easy to fly.

I appreciate the help!!
Thanks,
         Rafiki

Rafiki,

You've got the right idea. When the lift of the wing is increased, approach and landing will be difficult at best. Of course, you could next decrease wing incidence angle to help the landing. Then your high altitude cruise would be nose up and wouldn't look right.

I just read your last post again. Since you're looking for a private jet, you could start by throwing out all the passengers. Go to the (weight_and_balance) section and make sure the empty weight is correct (sometimes it consists of empty aircraft PLUS pax and crew, etc). Then, zero out all "station_load.x=" statements except for a small crew and your entourage.

You could also reduce the fuel capacity and plan on shorter trips. Just a thought.

Good luck with your customized CRJ.

Regards,
JerryH

Thanks for your help.

The .air file can be edited using a program such as "AirEd" to raise the overspeed alarm threshold.