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Altitude/speed control on approach

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undoctor

Joined: 21 Oct 2008
Posts: 212
Location: Bethelhem, PA

Posted: Sun Feb 12, 2012 7:58 pm Post subject: Altitude/speed control on approach

Kolbers,

     

     A short time ago I posted a question about reversing power for speed     and pitch for rate of descent when in the pattern.  The resulting     discussion was about as vigorous as if I'd have asked if anyone ever     tried flying their Kolb with the wings upside down.  So I emailed a     friend who flies for an airline and below is his reply.  If you're     interested in what he had to say start at the bottom, as usual.

     

     Jim and I talked this morning and he asserted that to do so is     "counter-intuitive", which is the way I felt when I first employed     the technique.  Of course, when my FI and I entered the pattern we     were always at 1400' ASL since Queen City Airport is 400' ASL, so     there was seldom much variation from landing to landing, therefore I     never had to "grab a handful of throttle."  But flying the FF into     different airports I've found conventional speed/altitude     adjustments are sometimes required.  Flying into Blairstown, NJ can     be intimidating with a hill where you turn downwind to base!   I'd     be interested to know if anyone else has been taught this or has     tried it.  

     

     It's really cold here, now, but I did get some flying in about 3     weeks ago, which isn't bad for a NE winter.  Hope you all are     getting your required altitude fixes.

     

     POI of interest to some about Jim; he won the 2009 Iron Butt Rally,     logging 12,706 miles in 11 days on his BMW motorcycle.  (And I feel     pretty proud of 11,014 miles in 3 weeks from Lansdale, PA to the     Atigun Pass on the Haul Rd. in AK and back home on my BMW     K100LT!!)   If you're interested you can Google "Jim Owen Iron Butt     2009" and click on the Rally Routing Seminar with Jim Owen     link. Last Fall he had the misfortune of low-siding his Beemer on a     rainy oil slick in Ky in a 24 hr. rally.  His cycle wasn't banged up     too badly, but he personally went into the guard rail legs-first and     did a number on his right leg.  He had it pinned and screwed     together and has nothing to show for it now except the scars.

     

     Happy flying, all.

     

     Dave Kulp

     Bethlehem, PA

     FireFly 11DMK

     

     

     

     ------

Ducati SS

Joined: 15 Oct 2009
Posts: 93

Posted: Mon Feb 13, 2012 3:51 am Post subject: Re: Altitude/speed control on approach

The technique described is not really reversing anything, the airplane does not know if it is at 500 or 5000 ft. If you are flying along in a Cessna trimmed for hands off at 2000 rpm and 90mph and increase rpm to 2400 you will not go any faster, you will climb at 90mph. If you pull the power to idle ( again without touching the yoke ) you will descend at 90mph.With the same 2,000 rpm 90mph trim you can pull back on the yoke and climb but you will lose airspeed. The problem with using pitch to control alt. on final is the constant change in airspeed, not so good when you are all ready close to stall speed. Trimming for approach speed and using power to control decent keeps the airspeed stable. Of course bumpy air or changes in lift/drag ( such as lowering flaps) may very well require pitch changes. Hard to prove in a Firefly with no pitch trim and the resulting unintentional pitch changes.

undoctor

Joined: 21 Oct 2008
Posts: 212
Location: Bethelhem, PA

Posted: Tue Feb 14, 2012 11:49 am Post subject: Altitude/speed control on approach

Hi Ducati (so what's wrong with a Beemer?),



I was aware that what you wrote was the way an ac tended to act, but I 

wasn't aware that the relationship was so precise.  Whenever we flew out 

of Queen City we had a 1,900' ceiling, still flying in LVI's airspace.  

When we got far enough south on the way to the practice area and were 

beyond LVI's space he'd have me increase power, bring the yoke back in 

order to maintain a lower/climbing airspeed,  but never taught me that 

the speed would remain the same as what I'd trimmed the AC for as we 

climbed if I didn't change the plane's attitude.  In the pattern he'd 

have me change the flaps 3 times, which is probably normal, but each 

increase effects your pitch and speed, of course.



In my FF I kind of "trim" my arm on the stick if I go from 4800 RPMs and 

60 mph to 5300 RPMs and 70 mph, otherwise I find myself climbing quite 

rapidly, which a FF is good at.  Interesting to learn all these 

relationships so you don't have to think about what's going on, but it 

becomes a part of you.



Thanks for the responses.



Dave Kulp

Bethlehem, PA

FireFly 11DMK

On 2/13/2012 6:51 AM, Ducati SS wrote:

 	  Quote: 	
		   



 The technique described is not really reversing anything, the airplane does not know if it is at 500 or 5000 ft. If you are flying along in a Cessna trimmed for hands off at 2000 rpm and 90mph and increase rpm to 2400 you will not go any faster, you will climb at 90mph. If you pull the power to idle ( again without touching the yoke ) you will descend at 90mph.With the same 2,000 rpm 90mph trim you can pull back on the yoke and climb but you will lose airspeed. The problem with using pitch to control alt. on final is the constant change in airspeed, not so good when you are all ready close to stall speed. Trimming for approach speed and using power to control decent keeps the airspeed stable. Of course bumpy air or changes in lift/drag ( such as lowering flaps) may very well require pitch changes. Hard to prove in a Firefly with no pitch trim and the resulting unintentional pitch changes.





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=366182#366182

gotime242

Joined: 09 Jul 2010
Posts: 52
Location: West Palm Beach, FL

Posted: Wed Feb 15, 2012 3:18 pm Post subject: Re: Altitude/speed control on approach

Its all airplane relative. The whole "pitch for airspeed, power for altitude" works for some aircraft, but when you fly different things that changes. 



In a Learjet for example the engines are above the cg/mounted high on the fuselage (similar to many biz jets). If you are level and add a bunch of power, its going to 1) gain speed and 2) pitch the nose down due to engine location...which then gains you even more speed. How fast we go is whatever the thrust levers are set at.

Last edited by gotime242 on Sun Feb 19, 2012 6:48 am; edited 1 time in total

Frankd

Joined: 28 Mar 2008
Posts: 64

Posted: Thu Feb 16, 2012 9:00 pm Post subject: Re: Altitude/speed control on approach

Hi Guys,



I've been reading this post and it seems we've gone away from the original question.  When I was just learning to fly my Dad told me that the throttle controls altitude and the stick controls airspeed.  I did not believe him until I actually found it was true!!  (cessna 172) 

Now.. I believe this question is being asked about Kolbs.. and it is still true.  



If you are a low time pilot and have not had this experience in a plane like a cessna or Kolb then it is something that might make your flying better.  



To the original person who posed this question,  if you are flying in the pattern and you are trying to hold airspeed,  set your throttle at some RPM that causes a decent,  say 1700RPM,  and then control your approach airspeed by pushing forward on the stick or pulling back.  You will find that there is a certain attitude to the plane that equals , say 50MPH, that you get used to.  



If the plane is in a steady attitude (nose down, or level) and you increase or decrease throttle the aircraft should start to climb or decend.  If you are approaching the runway at 50 mph but seem to be decending too quickly, apply a little power to reduce the decent. (and reduce power a bit if you don't seem to be decending enough!)



Sounds weird,  but after you think about it, it makes sense. 



I don't disagreed at all about other types of aircraft, lear jets, etc.. I have flown in an L39 where more power=faster  but thats a different type of flying. 



To the guy learning in a KOLB or any trainer,  I spent a ton of time in a citabria with an instructor,  to learn how to mix power and attitude to get it just right.   Keep 55MPH down the final approach in a kolb and keep going until right near the ground and then ease off the power and flare at the same time. 



Good luck with your training. 



FrankD

MkIIIXtra 1014S



14Hrs into 40hr flyoff time. No bent legs yet!

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Thu Feb 16, 2012 9:20 pm Post subject: Altitude/speed control on approach

If the plane is in a steady attitude (nose down, or level) and you increase

or decrease throttle the aircraft should start to climb or decend.  If you

are approaching the runway at 50 mph but seem to be decending too quickly,

apply a little power to reduce the decent. (and reduce power a bit if you

don't seem to be decending enough!)



Sounds weird,  but after you think about it, it makes sense. 



FrankD

 

Works a little different with a high thrust line pusher than does a tractor

aircraft.  Probably going to use a lot more pitch adjustment than power

adjustment.  Reducing power loses altitude, as does increasing power because

the high thrust line tries to push the nose down.



I generally shoot my landings power off.  If I can make my touchdown point

power off, I can make it if I lose the engine.  Was a habit I got into way

back in the early two stroke days when engines quit quite often at idle and

low  power settings.



Hope I still have an airplane at Gantt IAP.  Haven't checked on it in a

while.



john h

mkIII

Titus, Alabama

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

byoungplumbing(at)gmail.c
Guest

Posted: Fri Feb 17, 2012 7:58 am Post subject: Altitude/speed control on approach

If the plane is in a steady attitude (nose down, or level) and you increase or decrease throttle the aircraft should start to climb or decend.  If you are approaching the runway at 50 mph but seem to be decending too quickly, apply a little power to reduce the decent. (and reduce power a bit if you don't seem to be decending enough!)



FrankD



 	  Quote: 	
		  >>>>>>>>>


	


this seems to be implied, but not stated,   that this is for a GOOD landing approach.  and I'll agree 100 %.      however on a cross country trip,,,  you can from straight and level flight add power, retrim, and maintain altitude with an increase in airspeed.    and conversely, if you are 10 miles from the airport and 4000 ft above the pattern altitude.  you can trade altitude for increased airspeed by retriming for a lower nose attitude,  and by leaving the power the same  you will increase speed.   so there are areas of flight that go outside the rules you stated,,,  but retriming is required to do so.  again  for a GOOD landing approach I agree 100 %. 



boyd young

pj.ladd(at)btinternet.com
Guest

Posted: Sat Feb 18, 2012 4:50 am Post subject: Altitude/speed control on approach

How fast we go is whatever the thrust levers are set at.>>



Really?. Nothing to do with attitude then.



Pat

gotime242

Joined: 09 Jul 2010
Posts: 52
Location: West Palm Beach, FL

Posted: Sat Feb 18, 2012 12:44 pm Post subject: Re: Altitude/speed control on approach

 	  pj.ladd(at)btinternet.com wrote: 	
		  How fast we go is whatever the thrust levers are set at.>>



Really?. Nothing to do with attitude then.



Pat 	




Obviously. It also has to do with a million other variables. All i was saying is that different airplanes fly differently. And that was just a simple statement about one of those airplanes.

russkinne(at)mac.com
Guest

Posted: Sat Feb 18, 2012 7:38 pm Post subject: Altitude/speed control on approach

Pat

Good comment. I think how WELL anyone flies depends almost totally on attitude.

Russ

do not archive



On Feb 18, 2012, at 7:49 AM, Pat Ladd wrote:



 	  Quote: 	
		   

 

 How fast we go is whatever the thrust levers are set at.>>

 

 Really?. Nothing to do with attitude then.

 

 Pat

gotime242

Joined: 09 Jul 2010
Posts: 52
Location: West Palm Beach, FL

Posted: Sat Feb 18, 2012 8:26 pm Post subject: Re: Altitude/speed control on approach

 	  russkinne(at)mac.com wrote: 	
		  Pat

Good comment. I think how WELL anyone flies depends almost totally on attitude.

Russ

do not archive



	




I think we are on different pages... not once did I say that attitude has no role in airspeed/altitude. 



Everything is based off of attitude (angle of attacks), power and a lot of other things, but its the relationship between all those items that needs to be figured out....and determines what that airplane is doing. As in all parts of flight its all trade offs. This includes if your power is zero.



Again, my statement was regarding a different type of flying, one where power takes a larger role.



If you're on an arrival (level, descending...whatever) and atc asks you to maintain 310kts, i guarantee you the first thing you are going do is either add power or reduce it...this will then change the attitude of the airplane accordingly while you maintain your altitude or rate of decent. If you are level in cruise and ATC asks you to maintain Mach .80 or greater....are you telling me your going to pitch down to do that?



Power changes = attitude changes....the question is what happens first or what your primary tool for those changes are based off of what type of flying you are doing. Many airplanes are attitude airplanes, but some are flown by power settings....adjust attitude accordingly.



If you are flying a Kolb, Weedhopper, Cub, Citabria, etc...then yes, fly the wing. 



If you think how "WELL" anyone flies is based off "almost totally attitude"...and not the larger picture of relationships in all aspects...then you are looking at the spectrum, which include all types of flying, through a pinhole.

Last edited by gotime242 on Sun Feb 19, 2012 6:27 pm; edited 4 times in total

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Sat Feb 18, 2012 8:56 pm Post subject: Altitude/speed control on approach

Try low and slow.  Maybe we will understand.



BTW:  Who are you?



john h

mkIII

Titus, Alabama

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

gotime242

Joined: 09 Jul 2010
Posts: 52
Location: West Palm Beach, FL

Posted: Sun Feb 19, 2012 6:46 am Post subject: Re: Altitude/speed control on approach

 	  John Hauck wrote: 	
		  Try low and slow.  Maybe we will understand.



BTW:  Who are you?



john h

mkIII

Titus, Alabama 	




I have, and yes...that's a different story. I am just someone that use to have a kolb and still browse the forum. I fly a LR60 for a living. The kolb was some of the most fun flying I have done, i have a Citabria now. 



Have fun / fly safe.

byoungplumbing(at)gmail.c
Guest

Posted: Sun Feb 19, 2012 7:28 am Post subject: Altitude/speed control on approach

If you are level in cruise and ATC asks you to maintain Mach .80 or greater....are you telling me your going to pitch down to do that?

yes and no...   

if you are at mach .6  in level flight,,,  and atc ask you to go .8 and maintain altitude.    you will have to increase power,  and the extra speed will cause you to develop more lift,   so you will have to lower the nose untill the extra lift generated by the extra speed is canceled out, then you can maintain altitude.

if you were at mach 2.6  and atc asked you to go to mach .8   you would have to reduce power, and increase angle of attack to maintain equal amounts of lift.



like wise if you are in a kolb at 50 mph..  you will have to have aprox.  11 deg, +- in your main wings inorder to stay straight and level.   at that configuration the lift provided by the aircraft wings will equal the weight of the plane.    if you increase to 70 mph,  you will only need  aprox 8 deg +-  to develop the same lift,   so yes  you you will have to drop the nose, lower the angle of attack in the wings,  reduce back pressure on the stick,  (depending on trim)...      if you dont change the attitude,   and change speed from 50 to 70.   you will develope much more lift,,   and you will be in a climb.  



boyd

gotime242

Joined: 09 Jul 2010
Posts: 52
Location: West Palm Beach, FL

Posted: Sun Feb 19, 2012 7:56 am Post subject: Re: Altitude/speed control on approach

 	  byoungplumbing(at)gmail.c wrote: 	
		  If you are level in cruise and ATC asks you to maintain Mach .80 or greater....are you telling me your going to pitch down to do that?

yes and no...   

if you are at mach .6  in level flight,,,  and atc ask you to go .8 and maintain altitude.    you will have to increase power,  and the extra speed will cause you to develop more lift,   so you will have to lower the nose untill the extra lift generated by the extra speed is canceled out, then you can maintain altitude.

if you were at mach 2.6  and atc asked you to go to mach .8   you would have to reduce power, and increase angle of attack to maintain equal amounts of lift.



like wise if you are in a kolb at 50 mph..  you will have to have aprox.  11 deg, +- in your main wings inorder to stay straight and level.   at that configuration the lift provided by the aircraft wings will equal the weight of the plane.    if you increase to 70 mph,  you will only need  aprox 8 deg +-  to develop the same lift,   so yes  you you will have to drop the nose, lower the angle of attack in the wings,  reduce back pressure on the stick,  (depending on trim)...      if you dont change the attitude,   and change speed from 50 to 70.   you will develope much more lift,,   and you will be in a climb.  



boyd 	




Please re-read above.



"Power changes = attitude changes....the question is what happens first or what your primary tool for those changes are based off of what type of flying you are doing. ...some are flown by power settings....adjust attitude accordingly."



So...to change speed you WILL 1ST change power, THEN a resulting attitude change happens. Attitude comes 2nd, thus you are using Power to change airspeed as a primary tool, and a resulting pitch change will occur. So you are NOT going to pitch for mach .80, THEN increase power to maintain that altitude. Thats all im saying. 



Attitude is a byproduct of power settings when doing that type of flying. The phrase "Pitch for airspeed, power for altitude" does not fit in some scenarios. It would be more like "Power for airspeed resulting in an alternate pitch setting at a specific altitude to maintain the same total lift with the resulting airspeed." Lol



We are all talking about the same thing.

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