Landing stall speeds

[rturbett]

I feel good about my pattern work....but need help on the landings.  

I was given this advice:  Be on speed when crossing the threshold, 1.2 Vso for your given weight

But in looking up the stall speed in the POH for my 1980 m20 J, this was all I found:

 

Landing weight of 2740      There were no other pages that address different weights.  Any thoughts. or solid sources of information that can be trusted?

Thanks,

Rob

 

 

[ArtVandelay]

Vnew=Vold*sqrt(WTnew/WTold)

So 55 knots stall speed at 2740 becomes 50+ at 2300.

I use 1.3 which gives a landing speed of 65.

[Fly Boomer]

45 minutes ago, rturbett said:

I feel good about my pattern work....but need help on the landings.  

I was given this advice:  Be on speed when crossing the threshold, 1.2 Vso for your given weight

But in looking up the stall speed in the POH for my 1980 m20 J, this was all I found:

 

Landing weight of 2740      There were no other pages that address different weights.  Any thoughts. or solid sources of information that can be trusted?

Do a couple of approach-to-landing stalls and you will know Vso on that day.  Multiply by 1.3 or 1.2 and you have the most accurate answer you can get.

[201er]

Get an angle of attack indicator and take out the guess work.

[Shadrach]

11 hours ago, rturbett said:

I feel good about my pattern work....but need help on the landings.  

I was given this advice:  Be on speed when crossing the threshold, 1.2 Vso for your given weight

But in looking up the stall speed in the POH for my 1980 m20 J, this was all I found:

 

Landing weight of 2740      There were no other pages that address different weights.  Any thoughts. or solid sources of information that can be trusted?

Thanks,

Rob

 

 

Figure out the stall speed envelope and then you can interpolate based on estimated weight. 
For me landing weight can vary between 1950lbs (pilot, 1 hr of reserves, oil) and 2740lbs (MGW).

At MGW stall is 55KIAS. That means 1.3Vso (72KIAS) on final slowing to 1.2Vso (66KIAS) crossing the fence.

At 1950lbs stall is calculated as follows:

(1950/2740)Sqrt * 55 = 46KIAS 

46KIAS * 1.3 = 60KIAS on final slowing to 55KIAS across the fence.

This gives a VFR approach speed spectrum of 60 to 72KIAS and a threshold speed spectrum of 55-66KIAS. Fairly easy to interpolate the numbers in between.
 

The truth is many just fly too fast for any legal weight. There is rarely a need to cross the threshold above 70KIAS, yet many do as a matter of practice.

[carusoam]

Newer POHs contain more data…

including stall speed charts that include various weights…

Best glide speed is also a function of weight…

If you study a newer POH with the added data charts…

you might see a 10 Kt difference between heavy and light weights….

 

For the best logic in selecting the landing speed….  
 

There is a Mooney CFII around here that publishes an excellent package of info simplified into a basic chart….

I keep that as a handy reference for what speed to fly on final…

 

It is a real course on energy management, and safety management, when you have a 2k’ runway, surrounded by trees, and strong winds at altitude… and one windsock a half mile away….

+1 for the AOAi

But where is the fun in that… it presents you with that how much excess energy am I carrying now, in a single needle, or colored light stack.  No complex summations, or digging through a flight back for a chart…

Be sure to know how your AOAi is calibrated… based on a single configuration, or two?

PP thoughts only, not a CFI…

Best regards,

-a-

 

[ArtVandelay]

At MGW stall is 55KIAS. That means 1.3Vso (72KIAS) on final slowing to 1.2Vso (66KIAS) crossing the fence.

The truth is many just fly too fast for any legal weight. There is rarely a need to cross the threshold above 70KIAS, yet many do as a matter of practice.

OP, I would verify your airspeed indicator is accurate by landing on a calm day and comparing it with the GPS speed.

These speeds may not feel right depending on your experience, trainers can and are flown much faster. I had a CFI yelling at me about going to stall on final at 1.3Vso.

[Pinecone]

13 hours ago, Shadrach said:

The truth is many just fly too fast for any legal weight. There is rarely a need to cross the threshold above 70KIAS, yet many do as a matter of practice.

Some of us have much higher gross weights.  At 3200 pounds, it would be 71 across the fence (77 on final).

[Shadrach]

39 minutes ago, Pinecone said:

Some of us have much higher gross weights.  At 3200 pounds, it would be 71 across the fence (77 on final).

We were discussing the 2740 birds but sure, the heavier birds need more speed to maintain the same margins. Plenty of evidence that the heavier Mooneys are being frequently flown too fast on approach as well. 

Indeed under some conditions, I would likely add more speed margin to a 3200 lb Encore or a 2900lb J model as for all of their fine attributes, at max gross, they have the lowest power to weight ratios of the breed. 

[Vance Harral]

If we're going to be good nerds about 1.2 or 1.3 times Vs0, remember that this rule of thumb is based on calibrated airspeed, not indicated airspeed.

In the average Mooney, indicated vs. calibrated airspeed error in the landing configuration are pretty close, so it doesn't make a lot of difference.

It's more interesting to have this conversation about other airplanes, particularly the venerable Cessna 172.  Vs0 at gross weight in a 1978 172N is 41 KIAS.  But if you look at the airspeed calibration tables, 41 KIAS in the landing configuration is 48 KCAS, a difference of almost 20 percent.  48 * 1.3 gives you a rule-of-thumb approach speed of 62 KCAS, which converts back to 60 KIAS, per the airspeed calibration table.  That's smack dab in the middle of the 55-65 KIAS speed recommended for a normal landing in the 172N POH.  If you don't understand that, you might instead compute 41 * 1.3 = 53 KIAS, and either claim the 172 POH was written by a bunch of lawyers who added unnecessary fudge factor for liability reasons, or that the 1.3x rule is bogus.  But that would be bad analysis.  You can certainly make a nice, short-field landing in a 172 at 53 KIAS approach speed; but there's not much stall margin left at that speed if you're really at gross weight.

[skydvrboy]

Maybe you're having difficulty with your landings because you are too concerned about your airspeed indicator.  Sure, check it on each leg, but once you get 50-100 feet above the ground, just look outside the plane and fly it.  Slowly add back pressure to round out just above the runway and then hold it there as long as possible.  It will land when it's ready at whatever speed is right for the given weight.  On the flip side, you can almost guarantee a bad landing if you are checking your airspeed while over the runway.

[N201MKTurbo]

Also remember that the stall speed will be lower in ground effects. It's kind of hard to look out the window to make a good touchdown and look at the airspeed indicator at the same time, but if you are trying to hold it off for a full stall landing (which I do), you will probably find that it settles to the runway at lower than 55 KTS.

I check the airspeed on final, but after I'm over the runway I just look out the window. There is nothing inside that will make your landing any better.

[donkaye]

5 hours ago, skydvrboy said:

Maybe you're having difficulty with your landings because you are too concerned about your airspeed indicator.  Sure, check it on each leg, but once you get 50-100 feet above the ground, just look outside the plane and fly it.  Slowly add back pressure to round out just above the runway and then hold it there as long as possible.  It will land when it's ready at whatever speed is right for the given weight.  On the flip side, you can almost guarantee a bad landing if you are checking your airspeed while over the runway.

Approximately 475 students x 50 landings on average = 23,750 landings with students over 32 years.  Then about 2,000 landings in 4,523 hours in my airplane. Total landings made = 25,750  to a good approximation.  Then one landing video made.  (https://donkaye.com/landing-video}  No arrogance intended, only that I've done so many landings and experienced many ways they can go wrong, that I've learned over 56 years of flying my preferred way to land and teach landings.

50-100 feet is too high to take your eyes off the airspeed indicator.  Assuming I'm reading the next highlighted in red sentence correctly, this implies "dropping" into ground effect and holding the plane off until it is ready to land.  While this techniques may give a good landing, it will also extend the landing many hundreds of feet, since the holdoff is occurring in ground effect.

The best landings are made when attention is paid to BOTH airspeed AND slope.   When practical (no obstructions), the slope should be 3° for a comfortable descent rate and an airspeed of 1.3 VSo for the aircraft weight should be maintained.  The slope and airspeed should be maintained to about 10 feet agl, where in smooth no wind conditions power should be smoothly withdrawn to idle and the flare should be begun at such rate that the nose of the plane transitions from a 3° nose down attitude to the landing attitude of about 8° where the wheels are "rolled" on with the stall warning horn going off.  As the aircraft descends from 10 feet at a decreasing rate of descent, at least 2 stripes on a centerline runway should always be in view--all the way to touchdown.  The nose of the airplane should NEVER be so high as to obstruct the runway.  The "art" of the landing is practicing the rate of flare to dissipate ALMOST all, but not ALL, the energy at touchdown.  This allows for a controlled touchdown with minimum runway used.  

[N201MKTurbo]

Huh, I can usually make the second turnoff at CHD. That is shorter than most 172s. I guess you just have to get a feel for it.

But then again, to do that, I flare about 50 feet short of the runway. And touch down on the numbers.

[skydvrboy]

50 minutes ago, donkaye said:

Assuming I'm reading the next highlighted in red sentence correctly, this implies "dropping" into ground effect and holding the plane off until it is ready to land.  

I think you misinterpreted what I was saying, and reading it, I can see I didn't explain well enough.  It would be dumb to drop it into ground effect and hold it off the runway, that negates all the work you did maintaining your airspeed on final.  What I meant was, as you look out the window, just maintain power setting and airspeed until it's time to flair.  As you said, that's when you slowly take the power out while you round out and flair.  My point was that as long as you don't change airspeed or pitch attitude, your airspeed and rate of descent aren't going to change, so you don't need to keep looking at it all the time.  Many of my best landings were after my instructor covered up my airspeed indicator.  I wouldn't advocate doing that with a new student (and if the OP is struggling with landings, this certainly won't help), but all students should be able to land without their airspeed indicator before the end of their training.

I also didn't list what airspeed I'm shooting for on final, which might have added to the confusion, and yes, correct speed is important.  I've simplified it and use 80 mph when heavy, 75 mph medium, and 70 mph when light, so I'm not coming in with a lot of extra speed and just letting it float until touchdown.  As you said, that would eat up a lot of runway and I like to be off by taxiway B (1,900') since that's where my hangar is located.

 

[midlifeflyer]

I think a session with a CFI doing landings with the airspeed indicator covered will do wonders.

[Schllc]

I read these questions and answers regularly, but I don’t really understand how it could be applied in any consistent fashion at my home base. I am consistently held between 4 and 6k until I am within 5 miles.  If this wasn’t challenging enough, I am alternately stuck behind 150’s or big iron, with a smattering of 360’s and short approaches. 
anyone who has flown an ovation or acclaim know if you have to drop 5k in three miles you are going to get low, or slow, but not both. 
short of pulling to complete idle, not even speed brakes, flaps and gear can get me to 70knots sometimes.  
Below 100’ in vfr there is a lot of “feel” happening, and I have gotten to where I can choose which wheel touches first so I’m pretty dialed in. But I still can probably count time times on one hand that atc directions would permit the “perfect” approach as described above.  
how is this done with all of their meddling, do you just go around until they let you do it?

[PaulM]

If you are being held at 5-6K above pattern until 5 miles by ATC perhaps you can ask to fly the IFR approach.    Can you list your home airport, there might be history at a specific location.   Approach control's job is to hand off traffic to tower at either around pattern height, or on a listed approach and they are usually 2000' AGL at 5 miles. 

The only time I seem to usually get slam dunked IFR are at remote rural airports where you are talking to Center, or a distant approach controller and they assume you can come down like a Jet.   I just set my TOD to 500'/min and request the start of my descent.  I have never had a problem in a C or D on being ready for about a 90kt downwind or base.. to end up on a 75kt final.    If it is a class B/C that needs me to keep the speed up I can land with 1/2 flaps, and do final at 90kt..

[Schllc]

Downwind and base?  What I mean is APF is so busy I seldom get a pattern, but I do get minimum speeds.  
of course I can deny these and do laps for 30 min til, another window opens. 
I can manage it because I know my plane and I don’t bounce or take the whole runway, but it takes the whole bag of tricks and typically, there is little “standard” about landing here.  
summer is a little easier when the snow birds leave but that season gets shorter every year. 
oh… they usually handoff under 3 but the situation is already unfolding with me at 180 knots 3 miles away. 

[McMooney]

really does sound like you guys make this more complicated than it needs to be,

70/80 ish  until runway is made then just hold it off, landing will be short and sweet.

higher than about 80ish you're gonna eat a lot of runway but still just hold it off.  

note if  the plane really doesn't want to land, CHECK YOUR GEAR

[ArtVandelay]

really does sound like you guys make this more complicated than it needs to be,
70/80 ish  until runway is made then just hold it off, landing will be short and sweet.
higher than about 80ish you're gonna eat a lot of runway but still just hold it off.  
note if  the plane really doesn't want to land, CHECK YOUR GEAR

80ish?! I hope that’s mph.

That’s part of the problem, modern models use knots, old vintage ones use mph, can’t just memorize a number.

[McMooney]

44 minutes ago, ArtVandelay said:

80ish?! I hope that’s mph.

That’s part of the problem, modern models use knots, old vintage ones use mph, can’t just memorize a number.

on a normal runway just hold her off, patience is key, she'll land perfectly fine,  the problem happens when we get anxious and start  trying to force the issue.

so using this technique, my girl normally lands and is off the runway without using brakes in like 1500ish. 

treat her like it's a Diamond da40 and Not a Cessna 172 and you'll be fine

[Hank]

16 minutes ago, McMooney said:

treat her like it's a Diamond da40 and Not a Cessna 172 and you'll be fine

Thanks. I treat mine like a Mooney:  roll wings level at 85 mph on final, slowing to 75 mph minus 5 mph for every 300 lb below gross for that landing.

And no, these numbers won't work for a long body. But they're fantastic for my little C.

[PaulM]

20 hours ago, Schllc said:

180 knots 3 miles away. 

That seems a bit much.  If they are treating you like a jet, ask for piston single speeds.  Those 172's aren't doing 120kts in the pattern.   I was just down in Marco, and Ft Myers approach had me in a 500'/min descent @ 160 kts. I had no problem slowing down around 3000', and had the gear down by 2000' with a 90kt straight in to Marco.  I haven't landed at Naples for many years, but I remember a regular 90kt downwind to base to final.  Perhaps it was a slow evening.   At a class D I will be at 90kts in a downwind or base position.   That allows plenty of time to slow to 75 on final.  I've had downwind extended for 5 miles, I've done 360's but other than class B's "keep it up until 2 mile final"  it is reasonable.    

[William Munney]

Landing any airplane is a result of a stabilized approach….meaning airspeed and vertical descent rate.  By 500’ (1000’ in large airplanes) your airspeed should be stabile at the approach speed for your landing weight and you should be on a 3 degree slope (obstacles permitting).  Varying airspeed and/ or descent rates changes the landing picture and leads to your experimenting with every landing.  Consistent control over airspeed and approach slope reduces variables and results in consistent landings.  There is no substitute for a stabilized approach.

Gusty winds?  Add 1/2 the steady state HW and all the gusts up to 15 knots.