Much as I really love my 727, it keeps catching me out :-[ especially at difficult approaches like Toncontin etc...

With a close to full load, but very light on fuel, should the 727 be able to hold speed at level flight, with full flaps and wheels down?

I find that unless I hold a constant descent, even at full throttle, the speed just keeps bleeding off.

What am I doing wrong?  It seems the drag is massive!

Thanks

Any ideas guys?

Hi dougal.

The 727 is a plane that you need to watch carefully. Especially on approach! That said, I don't have any real problems with power on approach. I think the idea is to hold an airspeed of about 140-160 KIAS (LOU will set us right on that ;)). I try to maintain 140KIAS in landing configuration of Flaps 30^o during approach. There is a placard on the forward panel above the landing gear lever that states FLAP SETTING 40^o MAY BE USED IN AN EMERGENCY, so I rarely use 40^o flaps on approach and landing.

Hope this helps.

Mark

Did you try the great 727 modifications from the forum guys around concerning the actual performance of the 727?
I must say that I was sceptical first but now I'm a big fan of them and drive my 727-100 and -200 with those fixes.
The thinking behind those fixes is to make the plane behave just like mentioned in the performance charts and, aside from Lou's great tips, those are a real help then.

As both things are freely available, they are more than a tip.  :)

Below a certain speed you will enter the vicious circle of high drag leading to even higher drag, I think.
Since you are writing about some high throttle setting, you might pitch up when you see that you are descending to fast. This pitch will (first) lower the descend rate but then will significantly raise the drag value because of the now higher angle of the nose, so you are slowing down some more, leading to a higher descend rate which you then counteract by pitching even more up, and so on. Thrust is limited, drag can raise to enormous values though.
Especially with those mentioned free modifications of the 727 performance, you will find yourself being able to hold a steady pitch for "flying on the runway" and also getting the control over the descend rate by just the throttle setting, leading to a nice and "clear" descend.

Hi dougal,

Mark is correct - you need to keep a sharp eye on the 727.  :o

Small wing, big sweep and underpowered, that's why the 727 was nicknamed "The Pig."

At max landing weight do not get behind the power curve. When the pilots started checking out in the 727 from a straight wing piston there were some problems with high sink rates and low power settings.

First, the jet engine if allowed to spin down to idle, will take some time to spin up compared to the piston engine. This was really true in the early jet engines. It had been improved a bit in the newer, bigger fan engines.  Once the pilots learned to keep the jet engine spun up these crashes started to go away.

Second, the sweep of the 727 wing and all the monkey motion (aeronautical term  :P) of the slats and flaps caused pretty high drag compared to the straight, cleaner wing plane. Being a bit slow on approach in the 727 with high sink rate is a real trap since a last minute flare will just produce a different angle of attack at impact. Of course flying too fast on approach will lead to going off the far end of the runway. So being on the proper speed for the weight and keeping the jet engine spun up leads to more success on landing. Most airlines used a 1,000 AFE (above field elevation) foot check to insure the plane was configured for landing. (Gear down and locked, flaps set for landing.) Another check at 500 feet was used to see if the plane was in the slot for landing. The non flying pilot would call: 500 feet, on speed, sink 800 - or what ever the numbers actually were. If you were not on speed and/or sink was more than 1,000 fpm, a go around was mandatory! This was a big help in not being embarrassed by a hard landing, or worse!

I don't remember the exact "bug" speed for the weight (there was a placard which listed these speeds in the plane), but as an example, at a landing weight of 125,000# and flaps 30 I use 130 kts on final. A reminder, for every extra knot of speed it takes 50 more feet of landing distance. Also, standard procedure was to start the flare before power reduction during landing. This was especially important in cross wind landings - flare first, then kick out the crab, then maybe reduce power!  ;)

Flaps 40 was never used at TWA and was in fact blocked out on the flap handle. In an emergency, you could set flaps 40 using the alternate flap procedure. Flaps 40 was pretty high drag, and very noisy.

The biggest thing I can pass on to any student pilot is to NOT rush the approach. A stable approach usually leads to a good landing. A go around is better than trying to salvage a bad approach - plus you get extra flight time! ;D

Lou

Many thanks guys

I really, REALLY love the CS727.  Although I've had it since release, I've only recently got right back into it.

It is, without doubt, still one one the greatest airliner addons for FSX.  Well done Captain Sim!!  You were WAY ahead of the field on this one.

I'm assuming you guys are referring to this mod: http://www.captainsim.org/yabb2/YaBB.pl?num=1296889437

I'll try it.  All I've been doing so far, is slowly, slowly decreasing the two drag entries in the aircraft.cfg file, but I know that's not the way to go.

Another BIIIG mistake I've been making is the use of full flaps!

The more I fly this baby, the greater my respect for Lou and all those other skilled guys (and brave!!).  I guess more mordern aircraft pilots must have it real easy in some respects?

For me, by a big mile, the best airport to practice approaches (in any addon aircraft) is the payware addon version of Toncontin (MHTG).  It's just sooooo darn hard to get right.

Anyone know if 727s actually operated from there?

Once again... BIG thanks guys.  I appreciate the detailed info greatly.

Thank's Lou

As always, your explanations are much more clear than I can do.

If I let the 727 (much more so on the 727-200) get as slow as 130 knots, I seem to be at a huge risk of "losing it". That is why I aim for 140 knots.

It could be worth going to Avsim file library and searching for 727perf.zip (by Matt Zagoren) as the information in it is very helpful.

Mark

Yes, that's the right thread for the -200 mod, there's one for the -100 too. Mark is referring to the documents then. Matt Zagoren has collected and done some very interesting packs there.

I think MHTG is a great experience but for a pure practise of approach attitudes and power settings I would chose a medium sized field with a standard ILS (3 degree glideslope) and a straight in procedure to follow.
You can get a feel for the plane, together with memorizing the optics of this right speed/right setting/right setup approach there without getting distracted.
If you fly it manually and watch the deviation via the flight director, this practise will soon enable some feeling for plane on the approach. Touch&Go practise therefore builds the basis of all further things.

You can find me at Avalon (YMAV) with almost every plane I own from time to time because if you don't fly the same plane all the time, you soon lose this feeling for it, at least I do.  :-[
I you use the addon scenery there, you can also enable the photographers, which gives you some pressure to show the folks some nice approach.  :D

I was only pointing out some documents that could provide more helpful information. Although I have tried Michael2's mods for the -100 and the -200, I don't use them. I'm sticking to the Captain Sim settings (except for the increase of engine thrust I added to the -200). I'm happy enough with them like that.

Mark

CoolP wrote on Feb 26^th, 2011 at 10:33am:

I think MHTG is a great experience but for a pure practise of approach attitudes and power settings I would chose a medium sized field with a standard ILS (3 degree glideslope) and a straight in procedure to follow.

Yes indeed, you're quite right.  Always been a trait of mine though i'm affraid - trying to run before before I can walk :o

Will go practice some more with std approaches (it's just sooooo much fun!)

On a different theme...  I recently purchased the saitek multi-panel and switch panels.  While being very dissapointed with the units themselves for payware aircraft, I have got SOME good results with the CS727.

I can now opperate the autopilot from the the VC without the worry of keep loosing the 'popup' windows.

Mark, you pointing towards those docs stay a great tip for not only the 727.
I was just trying to say that the values given in those docs can only be matched when you use that "little" mod from Michael2.

I'm actually really glad to see that CS has such an open policy for posting user made modifications. So everybody can decide whether to use them or not.
I've found the 727 to be fun in the standard setup coming out of the box, but this flight tuning brought even more of it and also rendered those mentioned docs to be more helpful, meaning accurate when used for the CS 727.

This plane stays one of my favourites when e. g. flying to South America and even worldwide, when going for some "Heavylift" operations. A real classic and a lot of fun with that mod and the Civa INS in the cockpit.
When the 707 Cargo arrives, she might get replaced at some locations though.

dougal wrote on Feb 25^th, 2011 at 8:39pm:

Many thanks guys I really, REALLY love the CS727.  Although I've had it since release, I've only recently got right back into it. It is, without doubt, still one one the greatest airliner addons for FSX.  Well done Captain Sim!!  You were WAY ahead of the field on this one. I'm assuming you guys are referring to this mod: http://www.captainsim.org/yabb2/YaBB.pl?num=1296889437 I'll try it.  All I've been doing so far, is slowly, slowly decreasing the two drag entries in the aircraft.cfg file, but I know that's not the way to go. Another BIIIG mistake I've been making is the use of full flaps! The more I fly this baby, the greater my respect for Lou and all those other skilled guys (and brave!!).  I guess more mordern aircraft pilots must have it real easy in some respects? For me, by a big mile, the best airport to practice approaches (in any addon aircraft) is the payware addon version of Toncontin (MHTG).  It's just sooooo darn hard to get right. Anyone know if 727s actually operated from there? Once again... BIG thanks guys.  I appreciate the detailed info greatly.

dougal, I totally agree with you that the CS727 is the most awesome airliner for FSX!!!   Especially if you, like me, are in love with the real 727 and it's contemporaries.  I love the older, analog instruments.

I have not tried the mods for the -100 or -200 yet.  I did have issues getting the -200 to climb like it ought to, so I did make the static thrust change that Markoz posted.  That certainly did the trick for me.  

I'm not yet brave enough to try Toncontin yet, but my approaches and landings are starting to look really good, so I might try it soon.  

Well the Boeing 727 is renowned for being one of teh best short-field jetliners in the medium-range class. The wings, especially when full flaps are deployed, have leadign edge slats that really kill speed, as designed, mnow, full flpas aren't deployed until final, or short final usually, you approach at slats 15, then crosswind goes to 20, then 25, and finally flaps 30, you shouldn't be doing too much flying with full flaps, this like you said kills your speed. PLus, once you slow down this much, with this much weight and drag, it can take a while for the plane to regain thrust, and momentum.

Here's a fun fact: On the first flight of the Boeing 727 (also was the -100 the center engine surged on takeoff, then recovered. The first flight was shortened because the leading edge slats were stuck in the deployed position.

My advice and technique:

Download the flight model mod and follow the read me.  Next, remember in general that you pitch for speed and adjust power for altitude.  On approach, this is especially true when maintaining glideslope and approach speeds.  What you are experiencing is an increase in induced drag, which is the second type of drag that is produced whenever an aircraft is producing lift.  Induced drag increases when speed decreases.  Try and use the power to maintain the glideslope and pitch the nose for your airspeed.  I also try to maintain 220 kts around 10-12 miles out and gradually slow to around 140 knots while extending slats, flaps, and gear, and I reach the wind compensated vref speed around 100 feet above the runway.

Tight schedule there, audiohavoc, staying at 220 kts till only 10nm out.
I'm mostly catching the LOC at 180/flaps 5 and get down to 160kts/flaps 15 when going for the GS capture and following.
When it starts to point down, flaps 25 and the gear are deployed and when within 5nm to the airport, I'm looking for the final config (flaps 30) and speed.

The freely available docs describe this procedure when approaching with a coupled ILS and the "high" speed of 160 kts until 5nm out gives you enough motion to stay within the ATC's planning at busy airports as they mostly get upset when slowing down too soon.
As said, I think that 220 until 10nm out is very, very fast and the LOC capture (which should have happened well before this point) won't be that much fun for the old AP installation on the 727.

But I'm no Pro here, so correct me if I'm wrong. I'm just roughly following those mentioned docs and would fly higher speeds only with special planes (Concorde) or with the very heavy ones (747 loaded or so, not the 727 though).

CoolP wrote on Mar 12^th, 2011 at 5:25pm:

Tight schedule there, audiohavoc, staying at 220 kts till only 10nm out. I'm mostly catching the LOC at 180/flaps 5 and get down to 160kts/flaps 15 when going for the GS capture and following. When it starts to point down, flaps 25 and the gear are deployed and when within 5nm to the airport, I'm looking for the final config (flaps 30) and speed. The freely available docs describe this procedure when approaching with a coupled ILS and the "high" speed of 160 kts until 5nm out gives you enough motion to stay within the ATC's planning at busy airports as they mostly get upset when slowing down too soon. As said, I think that 220 until 10nm out is very, very fast and the LOC capture (which should have happened well before this point) won't be that much fun for the old AP installation on the 727. But I'm no Pro here, so correct me if I'm wrong. I'm just roughly following those mentioned docs and would fly higher speeds only with special planes (Concorde) or with the very heavy ones (747 loaded or so, not the 727 though).

220 is fast, I should have put 190-200.  It is a challenge though to practice some fast approaches, and the 727 generates a lot of drag with the gear out and flaps 30, and this can make fast approaches easier to handle than some of the more aerodynamic aircraft.

I fully agree on the drag ability of all the stuff on the 727. But despite the fact that she's able to slow down fast, this "jumping through the settings" would enable quite some hurry on the approach in my eyes.
As one should proceed calm and with enough time to react on possible errors, the slightly slower but more stable technique with the plane getting configured with enough time in between seems more promising to me.

I just thought about how I got "my" approach speeds, and please don't see my comments as critique on yours (which now also include the "190" setting).
I think that ATC talks you down to around 190 knots when they expect you to intercept the LOC. I heard those speeds most of the time when flying online and also remember hearing them on various cockpit videos.
Exceptions would be (at least online) a special/very heavy plane, but even the non-flap Concorde goes for 210-190 there (tends more to 210 though) and all the heavy stuff (or the bad slow-flyers, which would could be a 707 for example) seemed to aim for a max. of 190 then, mostly 180, to enable a smooth and stable LOC capture, being a very vital part on every precise approach.

They stay out at a min. of 160 knots then, until 5nm or so, for the ATC reasons given in the last post. So there's a range of 190 down to 160 for all approach related things in vicinity of being "final", while you slow down to your very special ref speed when being below 5nm out.

I've picked an example picture from the nice 727 docs from Matt Zagoren to show that the pre-landing config gets set soon while the speeds drop down real fast, especially when trying to catch one of those guidance signals (LOG and GS later).
http://img833.imageshack.us/img833/7497/ilsapp.jpg

So you can see a constant set-check-set-check cycle there, allowing to abort the thing when necessary and without getting in some sort of rush. I prefer it like this, I have to admit.
Maybe the real Captains around can offer their view on this too.

There will be exceptions around the planet of course, where this or that happens in another way as the somehow standard ones. ATC clearances might be one of them and I saw some EDDF controllers allowing the approach with no speed limits at all to enable some very fast descent before but also running the risk of getting the new pilots into the mentioned rush later.
In the rw (where this technique seems to come from), only Pros are flying, but in the sim, new pilots are more common. I'm often enough one of them.  :-/

For us 727 flyers, the rather slow reacting AP is another factor to consider. Overshooting the LOC is more likely to happen when you're above 180 knots I think.

I posted this issue in a different thread, too, that approach in the 727 is extremely difficult, and I'm not sure if its the model or the related issues with the pitch control and yoke oscillations.  When I try to fly an approach at under 160, it dives like brick.   If I pitch for 160 and then try to find the right power to hold it, it is difficult to fly.  I've tried hand flying it, and that's tricky too, because the initial increase in power tends to first decrease vertical speed and then increase.   I'm a real world pilot, so I know how to fly, but this thing can be tricky on approach.

Its been suggested to me elsewhere that you should fly the approaches much faster (as noted above as well), but that shouldn't be the only solution, as trying to shoot an ILS at 200 when others are doing 180 or less is going to make you unpopular with ATC.  

ddo2 wrote on Mar 14^th, 2011 at 2:21pm:

I posted this issue in a different thread, too, that approach in the 727 is extremely difficult, and I'm not sure if its the model or the related issues with the pitch control and yoke oscillations.  When I try to fly an approach at under 160, it dives like brick.   If I pitch for 160 and then try to find the right power to hold it, it is difficult to fly.  I've tried hand flying it, and that's tricky too, because the initial increase in power tends to first decrease vertical speed and then increase.   I'm a real world pilot, so I know how to fly, but this thing can be tricky on approach. Its been suggested to me elsewhere that you should fly the approaches much faster (as noted above as well), but that shouldn't be the only solution, as trying to shoot an ILS at 200 when others are doing 180 or less is going to make you unpopular with ATC.

That's pretty weird.  Even before I solved the wildly oscillating yoke problem with Acceleration, I could still fly fine ILS or visual approaches at 150-160 knots at flaps 15 or 25, no problem.  Are you using flaps?

Yup, I'm using flaps.    But, it still has a tendency to nose dive on approach.  I've tried pitching up with more power, pitching down with more power (the usual approach to a slow flight problems of being too slow and going down too quickly), and every other combo thereof.  

Sounds strange to me too (meaning that I haven't experienced your mentioned problems yet, ddo2). Before and after the flight model mod the 727 was a good handflyer and worked well on the precision approaches.
I recently did some touch&go training in the way I described earlier in this thread and everything worked fine, following the speeds in the additional docs (which are a great source together with using the FDE mod).

Can you try again or post your payload layout maybe?
I often had a fully loaded cargo -200 in the air (all containers are in), and around 45% of fuel, giving me around 69 tons to handle.
My MAC was in the operational range then and I was able to really follow the docs for landing her. Compared to handflying the 707, the 727 is a real charming planing while her older sister requires some work on the yokes.
From what I know, this matches the character of those two planes. 727 = fun, 707 = work.

Here's a quote from the fine docs regarding the 727 nose down tendency on the approach.

Quote:

BEFORE LANDING/APPROACH The speeds recommended for each flap setting allow considerable margin above stall for normal maneuvering and place the airplane in the most desirable attitude during final approach (about 3° to 4° nose-up).  Flap extension on the 727 pitches the airplane nose-down, especially when going from 15° to 40° of flaps.  The use of Ref +10 throughout final approach to touchdown will normally provide the most stable flight and desired airspeed.  When gusty surface winds are affecting the airspeed needle, add the airspeed needle bounce to the Reference speed; e.g., if needle is bouncing plus or minus 10 knots and Reference speed for existing gross weight is 120 knots, fly 130 knots as adjusted approach speed.  Total airspeed correction shall not exceed 20 knots. BEFORE LANDING BEFORE DECELERATING FROM: START LOWERING FLAPS TO: 200 kts 2° 190 kts 5° 160 kts 15° 150 kts 25° 140 kts 30°/40° Add 10 knots to above if aircraft is above 152,000 lbs; add 20 knots if aircraft is above 176,000 lbs.

I fly the approach in the 727 at landing weight of 130,000# or so & flaps 30 degrees at 125 to 130 KTS.

No problem at this speed - EVER!

Trying to land this plane at 160 or 180 KTS is way too fast! You would land on the nose wheel.

How would you stop without burning up the brakes or running off the end of the runway?

Lou

Since Lou has quite some real world background there, which makes it easier for him to determine the speeds, I once again recommend the fine docs for the 727 for all the other guys (including me) to get some hints on the speeds and settings.
See this nice diagram and also the table for the Reference Speeds here for example, perfectly matching Lou's experience and also fitting nicely to the 727 in the sim.
http://img228.imageshack.us/img228/2668/ref200.jpg


Lou, I'm wondering if, apart from speed tables and calculations, the 727 could be flown "AoA" of some kind.
So If I know the normal pitch attitude of the plane at final, I could adjust the power to fit that pitch (and descend rate) and would automatically be on the correct speed for landing at that weight without ever watching the Airspeed Indicator or knowing about the weight.
Am I right from theory there or is this something which doesn't work at all?

I should clarify my post-- when I say 150-160 kts when I am flying approach, I mean the earlier stages before capturing the ils and glideslope.  Once I am dialed in on the localizer, I slow down a bit, then slow down some more to 130-135 when on the glideslope.  

ddo2 wrote on Mar 14^th, 2011 at 2:21pm:

I posted this issue in a different thread, too, that approach in the 727 is extremely difficult, and I'm not sure if its the model or the related issues with the pitch control and yoke oscillations.  When I try to fly an approach at under 160, it dives like brick.   If I pitch for 160 and then try to find the right power to hold it, it is difficult to fly.  I've tried hand flying it, and that's tricky too, because the initial increase in power tends to first decrease vertical speed and then increase.   I'm a real world pilot, so I know how to fly, but this thing can be tricky on approach. Its been suggested to me elsewhere that you should fly the approaches much faster (as noted above as well), but that shouldn't be the only solution, as trying to shoot an ILS at 200 when others are doing 180 or less is going to make you unpopular with ATC.

What is your gross weight when this situation occurs?

CoolP,

Even though the 727 had an AOA probe, our planes did not display AOA to the pilot. The AOA information was sent to the stall computer and generated stall warning to the pilot. We did have a slow/fast pointer in the ADI that was part of the stall computer, but it was just used as a check to see how the speed for the flap setting looked.

The 727 at around 130,000# and at 130KTS ( just a bit fast ) would have about a three degree nose up attitude while on glide slope.
The highest pitch angle - in level flight -  was 10 degrees nose up, with flaps 5 degrees at 180 or so KTS. We tried not to fly around too much at this high deck angle since it was not easy to see traffic.

Having never flown with AOA I can't say what would happen exactly, but it stands to reason that at a certain weight and power setting you could fly a pitch angle and do pretty well flying the plane. This was a procedure we had in case we lost our airspeed indicators or loss of the radome.

Lou

Quote:

This was a procedure we had in case we lost our airspeed indicators or loss of the radome.

That situation came to my mind when looking for a reason to go via Pitch and descend rate only.
Thanks for the explanations, Lou.

Based on the comments above, I went back and reset my weights in the 100.  I set 59 passengers and about 5 cargo boxes.   Weight was about 16500 in passengers/cargo.  Then loaded 20% fuel in all three tanks and did some loops around KDCA.  MUCH better.  (Didn't bring the total weights and don't have them in front of me, but you get the idea.)  Now I need to test it in flight where the AP has been on, so I can see if part of it is the yoke oscillations.  But, was able to fly a stable approach at 140ish and do a couple T&Gs and a full stop.  

Thanks all!