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 10 Crash & Burn (Read 10042 times)
Ziggy
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Crash & Burn
Apr 27th, 2006 at 3:18pm
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Guys, I’ve crashed and burned on my 727 flights enough times to suggest I need a little help. First of all a little background. Everything I know about flying, I’ve learned from FS 2002, FS 9, CS and this forum (no real world experience other than as a jumpmaster). I have no problems with any of the default aircraft or my add-on fleet which includes CS’s Herc and 707. The 727 is another story. No problems with take-offs or in-flight operations, just VFR landings. I’ve had my best success by setting my flaps at 5% while maintaining an air speed of 160-180 kts at touchdown or 15% flap with an air speed of 150-160 kts. The latter seems more realistic, but it requires using considerable thrust during descent to prevent stalling. Any suggestions or comments would be appreciated. Thanks guys--- Ziggy Embarrassed
  
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Manny
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Re: Crash & Burn
Reply #1 - May 3rd, 2006 at 10:40pm
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160-180 kts is too fast. even for a fully loaded 747.

Here is the deal. You would need almost all your flaps in for landing.

I am a real world pilot..but of the General Aviation kind. So take what I am going to say here with a pinch of salt.

My understanding about the jets is, That a Jet engine takes time to spool. So if you come in to land with low power setting (you can land that that way), its not safe, cause, for some reason you want to go around, you push the throttles the engine will not spool in time, so you would cointine sinking and probably touch the runwy. Sp the trick is.. to come in with reasonable power (60% N1? n2?). This would then increase the speed, which you don't want either (you will run out of runway) so you add a lot of drag. (Lots of flaps). This way. You come in with reasonable power and lots of drag and hence slow speed. If you have to go around, its easier (quciker) to remove flaps (drag) while you have the engine already spooled up.

Yes.. this 727, once you stall, you cannot recover (don't know if it real) and hence the crash and burn. IMO, thats the best part of this 727. I love it.  Cheesy

With full flaps, try to maintain 130 kts and (don't go below 120 kts) and land.

Manny
  
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Ziggy
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Re: Crash & Burn
Reply #2 - May 5th, 2006 at 9:38pm
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Manny, many thanks for taking the time to answer my query. I'm a little paranoid about stalling, hence the reluctance to lowering my air speed. Certainly what you say makes sense so I will give it a try. So far I can only dream of landing this bird with an air speed below 150 knts. Incidentally, most of my flights are short, therefore, I frequently find myself landing with 97% of my fuel still on board. It occurred to me that I just might be too heavy? I have since adjusted my fuel load and am a lot more successful in eliminating the "crash & burn" scenario, but my landings are still what one might describe as "hot" (150-160 knts). Thanks again-- Ziggy
  
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Ziggy
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Re: Crash & Burn
Reply #3 - May 5th, 2006 at 10:28pm
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Manny, as an addendum to my last post, I just shot 3 landings with full flaps at 125-130 knots. Not a hint of a stall. I wouldn't call them quite textbook yet, but I'll get there. Many thanks my friend. Have a good flight--- Ziggy Grin Grin Grin
  
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Manny
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Re: Crash & Burn
Reply #4 - May 6th, 2006 at 2:04pm
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Ziggy,

Its good you are doing fine. Yeah. That full flaps with 60% power is very stable even at 120 kts. Its a lot more stable than no flaps, 150 knts and low power settings.

I have a feeling this 727 is more realistically modeled than other aircrafts. The others seem to be a little too easy and a little too stable to be real I suspect.

Thats what I  like about this 727. Its challenging like flying for real. Sometimes landing even a GA aircrafts on  gusty/windy day (other than Cessna 172) like tailwheel (citabria and decathlon) makes it real hard.  Why should these big guys be so easy to land... when they are in stall conditions?

BTW.. At AVSIM, there is a fantastic freeware scenary for St. Marteen Juliana airport.  and then you have this new Kai Tak (the old Hong Kong airport I have been landing this 727 at these two places. Its a riot.

Cool

Manny
  
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Ziggy
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Re: Crash & Burn
Reply #5 - May 6th, 2006 at 7:42pm
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Manny, I'll take your word on the realism bit. I have no real world basis for comparison. I do know that the 727 is the most/only challenging "bird" to land in my inventory. Now that I'm getting my air speed and flaps playing nicely together, I've still have to get the hang of sustaining runway alignment while making my final descent. The aircraft has a tendency to oscillate. I'm probably over-correcting? I'll give your AVSIM airport recommendations a try albeit a little off the beaten track from my normal flight paths. Thanks again for your help--- Ziggy  Smiley Smiley Smiley
  
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majord
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Re: Crash & Burn
Reply #6 - Jun 18th, 2006 at 11:36am
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Ziggy, it sounds like you're not planning your approach properly.  do youself a favour and have a good read of the operations manual, and print out the pages withhe following charts:  

take off speeds v1 r  and 2,

Vref  speeds

min manouvering speeds


Ill forget the v1,2,r speeds for the moment since they're for takeoffs.  you're interested in the vref chart, which is your landing reference speed, and min manouvering speed charts which show the MINIMUM  speeds for each flap setting including 0

thie Vref  table lists flap settings, and landing weights, to give you the perfect Vref speed. which you add 5 knots too (vref+5) or up to 20 knots to if you have for example a 15kt headwind.

to work out your landing weight you'll have to calculate, or take note of how mcuh fuel you've used in your trip. so do that first OR write down several vref speeds and work it out as you come up for approach.

now ill assume you're doing an ILS approach.. heres what you should be doing. PLease reference the NORMAL LANDING diagram at the end of the operations manual.

you need to come in at a level altitude, and at around 200kts, with no flaps ( this will vary as per the min manouvering speeds chart.. reference it but for most landing weights you'll see its around 200kts). the altitude you level at for your landing circuirt is listed on charts for aerodromes but if you're not using one, lets just say 2000ft. As you decelerate below 200  to come onto your landing circuirt, or even if its  long straight in approach,  you need to extend flaps as per that chart. as you can see in the landing diagram you're basiclaly selecting flaps as speed decreases to the min manouvering speeds.. by the time you're ready to intercept the glideslope (from underneath!)  you should be down to flaps 25  and be holding your vman+10  speed stable. now if you're coming in STRAIGHT, you can select flaps 30 and stabise on VREF+5,  if you're turning base and onto final, stay on flaps 25 vref+10 (for a flaps 25 setting!)  to make it easier and more stable to turn.

so as you turn onto final , further slow to Vref+5 , and if you choose to use them, select flaps 30 (DO NOT USE 40, ITS NOT NEEDED AND GIVES SLOPPY ROLL RESPONSE , it is completely blocked out on real 727s now anyway for noise abatment and can't be used) , and slow to vref+5 for flaps 30  which may be 130-140kts, now begin decending on the glidepath. either as per vor/dme altitudes , or just plain ILS.

As soon as you start decending,  CONTINUE paying attn to stablising your speed.. this is the most important part to a sucessfull landing. you want to get it right on vref+5 whilst maintaining a constant  glideslope... if your  ILS needle is showing you a bit high, then as you start to decend more, GENTLY ease off the power to compensate and stop your speed running away.. this will help prevent the oscillations you speak off.

if you're heading a bit low.. the same applies only increase power.. its critical you smoothly increase power a tiny amount as you decrease change your decent. and 'balance' it, i.e if the speed starts dropping to 134 133 , dont slam the throttles up or you'll overshoot..  

Remeber.. whenever you start inadvertently slowing on approach, whilst keeping the same decent rate, your angle of attack increases.. increasing drag, further trying to slow you..   increasing speed lessens the angle of attack lessening the drag, so it results in a total overshoot of your vref, and you having to 'dive' for the runway in order to keep the decent. BAD

Your approach when stable should have you showing about 1deg pitch up.. not nosed down.  aim for this to be the case the whole time. if it's not and your nosing down , you've calculated something wrong . slow, or increase  your Vref so as to maintain a fairly level nose.

as you get down to the 20ft mart. and not a moment before.   gently flare only 1 or 2 degrees and watch your vert speed, making sure if its heading for 0 too quickly to relaxe the pull back.

practice all  this and you'll be on your way.. I personally still make the odd bounced landing or float along,  as the flare is just so difficult in this thing IMO, you either  flare too late and impact the runway slightly, or float from pulling back too far.

goodluck zig!
  
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Ziggy
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Re: Crash & Burn
Reply #7 - Jun 22nd, 2006 at 8:08pm
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Majord, many thanks for taking the time to answer my query. The technical manuals have thus far eluded my ability to comprehend to the point of achieving much practical application. Too bad you weren’t the author as you definitely have a talent for translating Greek into very comprehensive terms. I shall follow your advice and take another look at CS’s flight manual. Perhaps it will make more sense to me on my next go at it? You’ve been a big help. Thanks again--- Ziggy
  
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Joeflyer
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Re: Crash & Burn
Reply #8 - Jun 26th, 2006 at 2:46pm
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Very good explanation Majord Smiley It is difficult to make a "greased" landing in the actual B727, so the sim aircraft is quite realisitc in that respect. I think I have made only 2 landings that weren't thumpers Grin
  

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vtxvtx
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Re: Crash & Burn
Reply #9 - Nov 11th, 2006 at 12:34am
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Ziggy wrote on Apr 27th, 2006 at 3:18pm:
Guys, I’ve crashed and burned on my 727 flights enough times to suggest I need a little help. First of all a little background. Everything I know about flying, I’ve learned from FS 2002, FS 9, CS and this forum (no real world experience other than as a jumpmaster). I have no problems with any of the default aircraft or my add-on fleet which includes CS’s Herc and 707. The 727 is another story. No problems with take-offs or in-flight operations, just VFR landings. I’ve had my best success by setting my flaps at 5% while maintaining an air speed of 160-180 kts at touchdown or 15% flap with an air speed of 150-160 kts. The latter seems more realistic, but it requires using considerable thrust during descent to prevent stalling. Any suggestions or comments would be appreciated. Thanks guys--- Ziggy Embarrassed

ZIGGY..THIS INFO IS FROM SOME ONE WHO HAS FLOWN THE 727 100 AND 200.30 DEG. OF FLAPS FOR LANDING..40 VERY RARLEY USED IN REAL WORLD DUE TO THE INCREASED ENGINE POWER NEEDED AND RESULTING NOISE AND EXTRA FUEL CONSUMPTION FROM THAT POWER SETTING DUE TO DRAG..IN THE 727 100 120 TO 125 K DEPENDING ON CONDITIONS WITH 30 DEG OF FLAPS AND 1 TO 3 DEG NOSE UP APPROACH AND AN N1 OF ANYWHERE FROM 60 TO 80 PERCENT DEPENDING ON THE ENGINE YOU ARE USING....THE 727 200 30 DEG OF FLAPS 1 TO 3DEG  NOSE UP AND 59 TO 65 N1 WILL BE NEEDED TO HOLD THAT SPEED AND GLIDE SLOPE AND ONLY SMALL ADJUSTMENTS SHOULD BE MADE IN THE N1 PERCENT... HE TOLD ME THAT IN REAL WORLD THE CAP WOULD SOMETIME SET ENGINE 1 AND 3  N1 AND POWER BACK OR INCRESE POWER IN NUMBER 2 ENGINE TO HOLD GLIDE SLOPE... CAUTION NEEDED FOR FLAIROUT NOT TO EXCEED 5 AND MAX 6 DEGREES NOSE UP ON LANDING AS YOUR TAIL SKID IS GETTING VERY CLOSE TO HITTING GROUND.  7 DEG AND OVER AT LEAST IN THE 727  200 AIRCRAFT YOU HAVE HIT THE TAIL SKID AND WILL BE CALLED TO THE CAP SIM OFFICE TO EXPLAIN YOURSELF..LOL J/K  IF YOU CAN HOLD 5 DEG ON TOUCHDOWN YOU HAVE DONE WELL... THE SPEEDS THAT CAPSIM PLANES FLY (AS STATED ABOVE) ON  LANDING ACCORDING TO THIS REAL WORLD PILOT IS THE SAME AS THE REAL WORLD MANUEL WHICH IS IMPRESSIVE ..THE REASON THE 727 CAN BE SLOWED SO MUCH ON APPROACH IS THAT THE WING FLAP ON THE 727 JUST DONT DEPLOY THEY EXTEND OUT (FOWARD) AND BACK INCREASING THE AREA OF THE WING    .THE CAP SIM 727S ARE ONLY FOR THE SERIOUS SIMMER AND AS WE ALL KNOW WILL PROVIDE A  DIFFERENT CHALLENGE EVERYTIME  UNDERLINE EVERYTIME YOU SHOOT AN APPROACH AND LAND....REMEMBER SET N1 ..MAKE SMALL ADJUSTMENTS FLY THE PLANE TO THE GROUND JUST LIKE THE FULL SCALE AIRCRAFT ...,AND AS A REALWORLD SINGLE ENGINE PILOT MYSELF REMEMBER THIS IMPORTANT FACT *A GOOD LANDING TAKES PLACE ON THE APPROACH * FLY A GOOD APPROACH AND YOUR LANDING WILL BE FINE FROM A CESSNA 150 TO THE SPACE SHUTTLE* ACCORDING TO MY 727 PILOT FRIEND  CAP SIM AIRCRAFT IS VERY ACCURATE AND VERY IMPRESSED. I HOPE THIS HELPED OUT ANYONE WHO IS INTRESTED.HAPPY FLYNG..
  
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nmaggie
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Re: Crash & Burn
Reply #10 - Jun 8th, 2007 at 3:11am
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All above good advice. Also, don't forget that the REAL culprit for a stall is critically high angle of attack.  Airspeed is really a proxy for AOA, more or less.  Don't forget to also consider:

-Bank angle (= higher angle of attack as the nose is pitched up trying to maintain altitude and/or tighten turn radius.  Also, increased G loads increase stall speed.)

-Sink rate (= higher angle of attack as the relative wind shifts from the leading edge of the wing more towards the underside of the wing.)

Be especially careful of your bank angle & sink rate while turning from base to final.  Don't get too agressive trying to line up on the runway & PAPI.

I'm a CS 727 "newbie," but I like Ops Manual Appendix 1 Vref's & minimum maneuvering speeds.  I use that as a flap schedule more or less, I like to end up around 140 kts with flaps 30 deg on final.  Floats a little though, & I'm still horsing the throttles a bit to keep glidepath as I'm learning the "feel.."

[Real-world general aviation pilot & CFI; "day job" as engineer "flying" heavy jet engineering sims]

  
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vtxvtx
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Re: Crash & Burn
Reply #11 - Jul 10th, 2007 at 11:55pm
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nmaggie wrote on Jun 8th, 2007 at 3:11am:
All above good advice. Also, don't forget that the REAL culprit for a stall is critically high angle of attack.  Airspeed is really a proxy for AOA, more or less.  Don't forget to also consider:

-Bank angle (= higher angle of attack as the nose is pitched up trying to maintain altitude and/or tighten turn radius.  Also, increased G loads increase stall speed.)

-Sink rate (= higher angle of attack as the relative wind shifts from the leading edge of the wing more towards the underside of the wing.)

Be especially careful of your bank angle & sink rate while turning from base to final.  Don't get too agressive trying to line up on the runway & PAPI.

I'm a CS 727 "newbie," but I like Ops Manual Appendix 1 Vref's & minimum maneuvering speeds.  I use that as a flap schedule more or less, I like to end up around 140 kts with flaps 30 deg on final.  Floats a little though, & I'm still horsing the throttles a bit to keep glidepath as I'm learning the "feel.."

[Real-world general aviation pilot & CFI; "day job" as engineer "flying" heavy jet engineering sims]

u will float...140 just a bit to fast for the 727 200 adv...130 135 depending on conditions
  
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