Performance issues with 727

[WebbPA]

I recently installed Mike Stone's B-727-200 package and I noticed some strange performance issues.  I can easily climb to FL250 at 300 KIA/1800FPM but to get to FL300 I have to climb in steps and allow the airspeed to catch up.  At FL300 I can barely maintain 300 KIA.

Is this a design flaw in the model or is it the realistic behavior of an older jet?

[Nexus]

I don't know if it's 100% realistic since I have never flown a 727 in the real life. But from what I've read and understood, the 727 had a lethargic (don't know a better word

[OTTOL]

Jim, I can't speak from any actual experience or numbers, BUT from my flying experience, this sounds accurate. I DO know that the 72' can not fly that high. We do contract work for Miami Air and Planet quite frequently, and a certain flight comes to mind. We dropped a 727 aircrew in New Orleans at 2am, and both left the airport within 1 minute of each other, heading for Fort Lauderdale. We "straight climbed" to 370 and accelerated to .83m. Going across the gulf, we communicated with the crew on ARINC. They could only manage 290, BUT smoked by us at .88m and a higher true airspeed, due to the lower flight level.

[WebbPA]

According to Boeing a 727-200 cruises at 30,000 to 40,000 feet at 570 to 650 mph (not sure what that would be in KIA or GS at 30,000 or 40,000 - it's probably easier to take it up and look at the readout on the GPS than to try to figure it out).

The panel I'm using is a custom modification that has autothrottle and altitude selection so that's not a problem. I like the panel because it has 3 sets of engine gauges and I have a generic fuel gauge so I can use it with the longer range, higher performance MD-11.

I'm glad to see there is no flaw in the model.  I just have a 1960's aircraft that performs realistically.

[born_2_fly]

i also experience this with both the 727 and the A330 i have been trying to get up to 37000 on IFR and i get the stupid warnings form atc telling me to continue up 2 my flight level but i cant its carrys on reaching stall speed!

[JerryH]

Jim,

I also fly the Mike Stone B727 with the Charles Fox revisions for an aircraft gross weight of 185K. Fox revised both the aircraft.cfg and .air files.

I have done some climb testing of this bird, because when I file IFR I want to be sure about actually getting to the requested altitude. My criteria is to climb and accelerate to 300 KIAS while gradually reducing VS in order to maintain the correct airspeed. When the aircraft can no longer maintain the correct airspeed at a VS of 500 fpm, that is my measure of ceiling altitude. In the case of the B727, if airspeed reaches Mach 0.78 then constant Mach becomes the speed control.

My test for a takeoff weight of 185K will get the bird to 30,000 ft at 500 ft/min when airspeed begins to drop off. With only half of the fuel (takeoff weight of 152K), the B727 gets to 38,700 ft. At this higher altitude, airspeed control has switched to Mach 0.78 and Mach number is beginning to drop off.

This is my way of measuring cruise ceiling. We all do it a little differently. That's why I offered all the grimy details. Hope this is useful to you.

Cheers,
JerryH

[IanK]

Hi,
have a look in the Flight Manuals extracted here:

http://www.edwinn.com/flightsim/727_manuals/

Ian