FJS B727 power settings

[brucek 38]

I retract flaps and accelerate to 250 KIAS, then engage the AP with IAS-Hold. I get around 2,000 fpm in the climb up at red-line on the thrust, but above 10,000 feet the performance of the engines begins to drop off (as expected) and ROC falls eventually to around 1,000 (or less) fpm. I know that payload and fuel is a factor, but is 2,000 fpm at 250 KIAS usually unachievable with the 727 at higher altitudes? Increasing thrust usually results in the proverbial fire alarm in engines #1 and 3.

 

Thanks, Bruce.

[JRBarrett 3,120]

I retract flaps and accelerate to 250 KIAS, then engage the AP with IAS-Hold. I get around 2,000 fpm in the climb up at red-line on the thrust, but above 10,000 feet the performance of the engines begins to drop off (as expected) and ROC falls eventually to around 1,000 (or less) fpm. I know that payload and fuel is a factor, but is 2,000 fpm at 250 KIAS usually unachievable with the 727 at higher altitudes? Increasing thrust usually results in the proverbial fire alarm in engines #1 and 3.

 

Thanks, Bruce.

At altitudes above 10,000 feet, the wing of the 727 is designed to be most efficient, and generate the maximum lift, at a speed of approx 300 knots IAS.

 

Assuming that you have already set your final cruise altitude (eg: 33,000 feet) in the altitude selector, when reaching 10,000 feet in the climb, pitch down to allow the aircraft to accelerate. (Maintain engine thrust as high as possible, while insuring that N1 and EGT remain below the red line).

 

When you pitch down to accelerate, your rate of climb will drop off, but this is entirely normal. Once reaching 300 knots IAS, engage the autopilot in IAS HOLD mode. Now, the autopilot will automatically control pitch to maintain 300 knots.

 

The aircraft will start climbing once again once speed is stabilized at 300 knots. The actual rate of climb you get will depend on engine thrust, and is also dependent on total aircraft weight and the outside air temperature. All other things being equal, you will get the maximum rate of climb when lightly loaded, when the OAT is cold.

 

You may not be able to maintain a 2000 FPM climb in summer, when air temps may be quite warm, even at higher altitudes. Whatever rate of climb you get, is what you get. The important thing is to keep your airspeed at 300 knots IAS with pitch, and keep engine thrust below red line.

 

When climbing in IAS HOLD mode, your rate of climb will be directly controlled by engine thrust. To increase climb rate, increase thrust. (Staying below red line). To decrease climb rate, decrease thrust.

 

When the Mach indicator reaches approximately Mach 0.78, (which will happen around FL270), switch the autopilot to MACH HOLD mode.

 

Never, under any circumstances, attempt to climb in VERT SPEED mode above 10,000 feet. Doing so is extremely dangerous, and could easily result in a stall at higher altitudes.

 

Switching to VERT SPEED is acceptable if you want to smoothly decrease rate of climb as you are about to capture your cruise altitude, but in all other situations climb only in IAS HOLD or MACH HOLD.

[brucek 38]

Thanks Jim, being used to flying a C172 in RL, with a very different wing to the B727 I now realize that I am too slow at 250 KIAS and maybe even "behind the curve". An aircraft with a wing and sweep-back like the B72 is a whole different animal, even compared to other jet aircraft.

 

It's amazing how Boeing engineered the B72 to be fast and slippery, with no apparent focus on fuel consumption and wing efficiency throughout the envelope, as aircraft today are designed to do. It's a real "thoroughbred"....

 

Thanks again, Bruce.

[JRBarrett 3,120]

Thanks Jim, being used to flying a C172 in RL, with a very different wing to the B727 I now realize that I am too slow at 250 KIAS and maybe even "behind the curve". An aircraft with a wing and sweep-back like the B72 is a whole different animal, even compared to other jet aircraft.

 

It's amazing how Boeing engineered the B72 to be fast and slippery, with no apparent focus on fuel consumption and wing efficiency throughout the envelope, as aircraft today are designed to do. It's a real "thoroughbred"....

 

Thanks again, Bruce.

You're welcome. Yes, climbing at 250 knots would put the aircraft on the low side of the optimal lift/drag curve.

 

The 727 had a "wing for all seasons". Highly efficient in cruise, but capable of supporting surprisingly low approach speeds (for a large aircraft) with its many lift augmentation devices: both slats and Kreuger flaps on the leading edge, and massive fowler flaps.

 

The amazing thing to me is that the engineers who designed the wing were working primarily with graphs, slide rules and wind tunnel models - it predated digital computer modeling by quite a few years.

[brucek 38]

Wasn't the B727 the second commercial jet aircraft that Boeing designed, after the 707 (which I always thought had no leading edge devices and a much simpler training flap system)? It's amazing that the engineers figured out how to put all those lift augmentation devices onto the wing. I used to fly on the 722's a lot when I lived in Australia in the 1980's, on the MEL-SYD-MEL route for business, but never really appreciated these birds for what they were....

 

I would love a simulated version of the RE model with JT8D-217C engines...

[BrianG 12]

 

 

Wasn't the B727 the second commercial jet aircraft that Boeing designed, after the 707 (which I always thought had no leading edge devices and a much simpler training flap system)?

The 707 did have leading edge devices but because the 727 lacked wing mounted engines, the entire leading edge length could be fitted with leading edge lift devices, thus giving it an advantage over the 707 in lift capability. Plus, it had a triple slotted flap system to further enhance lift along the trailing edge (with no engine interference) again running the entire length of the wing. Very ingenious considering the lineage. The 200 version could haul as many passengers as the 707-300 intercontinental,  but of course get into much smaller airports. I think a lot of people forget the significance of the 727 in terms of how it changed and revolutionized modern jet travel.

My recollection of the 727 wing design may be inaccurate so please correct  me if I'm wrong.

[JRBarrett 3,120]

The 707 did have leading edge devices but because the 727 lacked wing mounted engines, the entire leading edge length could be fitted with leading edge lift devices, thus giving it an advantage over the 707 in lift capability. Plus, it had a triple slotted flap system to further enhance lift along the trailing edge (with no engine interference) again running the entire length of the wing. Very ingenious considering the lineage. The 200 version could haul as many passengers as the 707-300 intercontinental, but of course get into much smaller airports. I think a lot of people forget the significance of the 727 in terms of how it changed and revolutionized modern jet travel.

My recollection of the 727 wing design may be inaccurate so please correct me if I'm wrong.

Your recollection is spot on. The design goal for the 72 was to be able to serve smaller airports, with relatively short runways, and the engineers succeeded brilliantly. The flaps are far more complex than those of the 707, yet the design was extremely rugged and reliable. My very first flight on a jet airliner was on a Continental 727-200 in 1973, and every succeeding airline flight up until the late 1980s was on a 727. The aircraft was a workhorse for multiple airlines.

 

In any case, FJS has done an outstanding job with the X-Plane version of this aircraft. It is my all-time favorite for XP!

[BrianG 12]

In any case, FJS has done an outstanding job with the X-Plane version of this aircraft. It is my all-time favorite for XP!

 

The 727 is my all time favorite AC. I had many 727 RL flights back in the day. 

Being I don't have x-plane, I only have the CS 727 for FSX. With many mods I'm reasonably happy with it but the FJS version sounds even better. Might have to get X plane if for no other reason. Seems to be a very favorable response to this version.

[Swe_Richard 1,175]

[quote name="JRBarrett" post="3454110" timestamp="1468813539"

In any case, FJS has done an outstanding job with the X-Plane version of this aircraft. It is my all-time favorite for XP!

 

I could not agree more! This has become my favourite aircraft for XP. It is absolutely brilliant. And really beautiful as well.

[wigerup 1]

I have a wish from you. Can you explain the function of the Autopilot and Flight Director in B727-200 adv, and also with conjuction wit x-fmc like in FJS B727 v2.

Would be so glad if yoy can help with this.

Kind Regards

Bjorn