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Stall speed and approaches

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UA-RESURRECTED

Does this mean I failed?
Joined
Nov 3, 2005
Posts
126
For light aircraft, is there any general rule about how far above stall-speed you should be on approach to land? This is assuming no wind/gusting conditions.

For example, the Cherokee probably stalls somewhere in the neighborhood 58MPH with partial flaps. (Yes MPH, this aircraft was built in 1965).

I want to experiment with making slower approaches to land, because I've been using 80MPH, and I still seem to float just a little too much and this generally results in poor landings. How slow can I get this aircraft on final approach, and still be safe???
 
UA-RESURRECTED said:
For light aircraft, is there any general rule about how far above stall-speed you should be on approach to land? This is assuming no wind/gusting conditions.

For example, the Cherokee probably stalls somewhere in the neighborhood 58MPH with partial flaps. (Yes MPH, this aircraft was built in 1965).

I want to experiment with making slower approaches to land, because I've been using 80MPH, and I still seem to float just a little too much and this generally results in poor landings. How slow can I get this aircraft on final approach, and still be safe???
General rule of thumb, assuming no manufacturer's information, is 1.3 Vs.

First thing I'd do is verify that you're working with IAS. Your 1965 Cherokee probably has the arcs and radials marked in CAS rather than IAS. With a 58 mph Vs, 1.3 Vs would be about 76 mph...not too far from your 80 mph target. Compare this with the airspeed calibration chart in the POH.

Second, are you using the stall speed for your weight, or the "max gross" stall speed? If you're substantially lighter than max gross, the working speeds would be lower than the "published" numbers. Remember...if you're 10% faster than you should be, your landing distance increases by 21%, and a lot of that will be "float".

Fly safe!

David
 
Which model? Those older manuals don't have much information. I have one for a Cherokee 180G and it recommends an approach speed of "about" 85 mph flaps up with a reduction of 3 mph for each notch of flaps, which would give you 76 MPH for a full flap landing at max gross weight.

And, as David said, that number is for max gross weight and can be lowered for lower weights. The formula for reducing speed for all load-based speeds that are given at max is

V1=V2 * Sq Root (W1/W2)

Where:
V1=Airspeed you are looking for
V2=Published airspeed for a given weight
W1=Weight for which airspeed is to be determined
W2=Gross weight for which airspeeds are published
 
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Try holding 1700rpm and using your pitch to maintain 80mph (70kts) and full flaps on final, assuming you are on glide slope. The POH is a good thing to go by, obviously. I would maintain 80 mph and pull the power to idle when you can glide the rest of the way.

And...don't try so hard. Relax and let the airplane fly. Get it down iin ground effect. It will do the rest by itself--it will come down when it's ready. Let me know how it works for you.
 
This would be a Cherokee 140, and as midlifeflyer said, the manual has very little information.

The manual claims the airplane should be trimmed to a speed of 85MPH with the flaps up during approach. This is kind of confusing because my instructor has been using 2 notches of flaps. We have never approached/landed in a clean configuration.

As far as using full-flaps on approach, I guess I could try it, but again, we've never done this.

Anyway, it looks like 80MPH is indeed the correct approach speed. Probably shouldn't be getting it much slower than that...
 
dude seriously ASK YOUR INSTRUCTOR!! thats his job. and if he hasnt done full flap landing with you before HES NOT DOING HIS JOB. you pay alot of money fot this and any info that he is holdong back is very unprofessional. GO ASK HIM!!
 
UA-RESURRECTED said:
For light aircraft, is there any general rule about how far above stall-speed you should be on approach to land? This is assuming no wind/gusting conditions.

For example, the Cherokee probably stalls somewhere in the neighborhood 58MPH with partial flaps. (Yes MPH, this aircraft was built in 1965).

I want to experiment with making slower approaches to land, because I've been using 80MPH, and I still seem to float just a little too much and this generally results in poor landings. How slow can I get this aircraft on final approach, and still be safe???
As others have stated, 1.3Vso is the defacto standard.

If you want to "experiment" with slower approaches, take the cherokee up to about 3000agl on a smooth day and simulate a landing approach. Descend from 3000 to 2000 using a reasonable descent rate and vary(lower) your speed on successive descents until you find the lowest speed you feel comfortable and in control. IIRC, a cherokee will give you plenty of stall warning, so you should there's nothing to worry about. Just keep on going slower and slower until the thing starts to feel mushy. Even at your new, lower approach speed, you're going to get a little float because of ground effect, but once you learn to get it slow on approach, you'll be amazed at how short you can land a cherokee.

:)

PS, after reviewing my original post, I'd like to add one thing. You're flying a light plane with no known handling deficiencies......Learn to fly it by feel, not by the numbers. You'll get plenty of time later, assuming you progress to swept wing jets, to fly "by the numbers". In the early days of aviation airplanes were intentionally designed to allow the pilot to feel the wind for the purpose of flying by feel.
 
UA-RESURRECTED said:

As far as using full-flaps on approach, I guess I could try it, but again, we've never done this.
I'm not a Cherokee expert, but this seems strange. I've done a landing or two and a lot of flight training (from both sides of the cockpit), the only time I didn't use full flaps was if there was a special circumstance (practice no flap landings, partial flaps in gusty winds, I forgot to put in the last notch, et cetera). This has been the case for every airplane I have ever flown (again I'm no Cherokee expert).

Here's another thought. Keep your speed up until short final. I'm guessing that the Cherokee 140 bleeds energy (airspeed) like every other Piper I have flown, quickly. Try pulling the power out a little sooner, so that if you are at 80 mph on final, you cross over the numbers at 75 mph (assuming you are using a runway with a 1000' aiming point, if you are aiming for the numbers back this point up 1000'). I used to fly a Mooney that tended to float if you carried any extra speed. The trick to good consistant landings in that airplane was to be on speed. Many people who flew the same airplane (including me for a while) would float way down the runway and blame it on the airplane saying that "it's hard to land". It's not that it was hard, it just was not forgiving to extra airspeed. The Cessna 172 lightly loaded (which describes most training missions) exhibits similar characteristics, but the Land-O-Matic landing gear is somewhat forgiving, so you can get away with less than good landings in a 172 where you can not in the Mooney (most Mooney drivers have seen the "Mooney bounce" at one time or another). I suspect that the Cherokee is more like the 172 than the Mooney and that "less than good" landings can be accomplished. Remember, airspeed control is critical, not that you have to be right on speed, but you don't want to carry too much speed, and if you are fast be patient and let the airplane land when it's ready (just above stall speed).

Good luck.
 
Not to sound rude, but if your having trouble landing its probable beacause you need to perfect your skills and not blame the airplane or procedures. It will land fine with that approach, eaven with a 90kias approach off an ILS. The flare is there to burn off that extra airspeed prior to touchdown. To answer your question. buy the airplane flying handbook from the FAA.
 

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