Is it easy to porpoise it on landing?

[briansommers]

I'm trying to figure out if I have my joystick setup wrong or I'm not a good enough pilot.

Every time I come in to land and start my flair. I start to porpoise the plane.
I give it a bit up and then it goes waaaay up real fast then I let it settle and rinse and repeat until bam on the runway.

I did manage to get a total greaser one time yesterday. So far I've got only 3 landings on it and 2 out of the 3 are terrible.

I'm using fsuipc for my joystick curves/sensitivities.. should I not be using that or have it set to zero?

thanks.

[ilya1502]

Can you record a video?
Also, how do you try to recover, I mean, to stop porpoising?

[Piper_EEWL]

You should have your sensitivity set high and your bull zones set to zero or near zero. Here is a post by Scott that explains why.

Also when flaring do not try to pull the nose up. You should try to get the wheels just a couple of millimeters (or an inch ) above the ground and the just try to hold the plane there by slowly pulling back on the elevator. That will make the nose come up slowly as the speed bleeds of. Once you've slowed down to the stall speed the plane will just settle down on the runway. There's a couple of threads here about this on the forums. I'll try to find them and post the links here.

[Nick - A2A]

Brian - you may want to check this thread out if you haven't already. Some useful tips and comments on in-sim settings and landing the Comanche.

Cheers,
Nick

[Dogsbody55]

I won't mention controller calibration, as others already have. As to technique, porpoising on landing can often be caused by your landing speed being too high. I find the best way of landing the Comanche is to make final at 75 to 80mph. Begin your flare as the runway suddenly grows big in your windscreen and cut the throttle. Fix your eye on the far end of the runway and carefully hold the plane off. Depending on aircraft weight, touchdown should occur at about 60mph or even less. Maintain back pressure on the yoke after touchdown to keep weight off the nose wheel. Practice some circuits and you should make good landings. With practice, you should find that the more you reduce your controller inputs, the smoother you will fly in all situations.


Hope this helps,
Mike

[AKar]

Comanche is perhaps the hardest from the A2A GAs to land "perfectly". It is quite easy to land rather firmly almost to the desired spot, but a really nice smooth one doesn't come easily.

Many sim airplanes are seemingly modeled so that they feel "nice". In A2A airplanes, there apparently is a strong emphasis on reproducing the real airplane's traits, be them nice or not. That leads into some frustration every now and then.

-Esa

[William Hughes]

On final too fast - try it at 70 knots and make sure the flaps are all the way down. The A2A sim aircraft match the real ones really closely and the Comanche is well known as a challenging aircraft to make a smooth landing in. Especially if you have too much energy on final.

[ClipperLuna]

Nice to read some of these comments; I thought I might have been the only one finding the Comanche more challenging to land than the others. My solution was to come in at 90 mph (flaps 40), but pull the power back to idle earlier than I do the Cherokee or the Skylane.

Still, I can’t help but wonder why does it seem I’m coming in too fast in the Comanche when I bring it in at 90 mph and pull the power back at the same time I do in other airplanes? I did some calculations. The Cherokee POH gives us a normal approach speed of 76 mph flaps down, and that of the Comanche a speed of 90 mph, flaps down. The landing configuration stall speed of the Cherokee is 55 mph and that of the Comanche is 64 mph. These stall speeds are 72% and 71% of the landing speeds respectively, so the safety margin speed over the stall is roughly equivalent. So why does the Comanche seem to float more? More susceptible to ground effect? Does it not bleed its energy off as readily when you pull the power back to idle?

[William Hughes]

It has a different style of wing than a Cherokee. Different flight characteristics. The aircraft also performs quite differently under different loading conditions. Landing a 2900# loaded Comanche (mains, tips, four passengers) is very different from a 2300# Comanche (one person mains).

Stall speed dirty (full flaps, gear down) is 54 knots at max gross weight (generally 2,800 lbs). A single pilot aircraft with an hour of fuel remaining might weight as little as 2,000 lbs. Stall speed in this condition might be as low as 46 knots. Remember that the ratio of the square of the stall speed is proportional to the G factor in turns? Same thing with weight - it works out the same way if the weight goes down - stall speed goes down.

So a lightly loaded Comanche (2000#) would stall dirty at as low as 46 knots. Applying the old rule of 1.3 stall gives an approach speed of 60 knots. It is a fun flight to test this out for yourself in a lightly loaded aircraft, actually.

So if you come in at 70 knots (approach max gross) in a lightly loaded Comanche, when you level off, you need to bleed out 24 knots of speed before it settles onto the runway at 46 knots. You might be waiting for a long time with that big wide lightly loaded wing in ground effect on a cold day with no headwind...

If you come in at 60 knots, then you level off and bleed away 14 knots. Much less time spent watching the end of the runway swoosh toward you and much less likely that a gust of wind pops you back into the air.

So, irl, I keep in mind that if it is just me at the end of a long flight with an hours fuel remaining, then my final approach speed is actually 60 knots. If the airplane is heavy (I came around and landed right after takeoff with all my passengers) then my approach speed might be 70 knots plus a bit. You hardly ever land heavy. Short one hour sightseeing flights have two people and the mains only (2400# at landing, stall 50 knots, approach 65 knots). 90% of my flights are this category. I usually add 5 knots for gusts unless it is one of those glass smooth evenings or mornings.

Basically, people bringing up Comanche landing hassles are too fast, so they float down runways, bounce in the air, wheelbarrow it on, etc. Try calculating an approach speed based on the actual weight of the aircraft and notice how easy it is to stop and how pleasantly she settles onto the runway at the slower speeds.

[William Hughes]

More to the point 90 mph is about 77 knots and that is too fast (for full flaps) unless you have a lot of gusty wind and the Comanche is at maximum gross weight.

[Great Ozzie]

William, you have said you are a Comanche owner, so I hate even to chime in here... but what you have said is what I would expect.

ClipperLuna... Along the lines of where you where going with the percents - it is typical to talk in terms of "1.x" of Vso. For example, where there are no recommended speeds in the POH and no gusty conditions - 1.3Vso for normal approach, 1.2Vso for short-field (over the fence).

I would go with William's suggestion of 80mph on final. That's right between 1.2 & 1.3Vso - also 80mph is given as a book number for Short-field landing. Maybe some of the floatiness is due to the wing of the Comanche not being as draggy (more efficient) than that shorter, stubbier Cherokee wing. And max flaps for the Comanche is 27° as opposed to 40° for the Cherokee. So I'd expect more drag from that last position on the Cherokee. But then there's the Comanche cowling and retractable gear that I would think add more drag.

Looking at the Landing Distance data - for the same weight (2400lbs) there isn't a whole lot of difference between the two aircraft (100-150 feet or so?). If there is *a lot* of float with the Comanche, I'd attribute that to that to higher landing speeds. Airspeed control is so important.

Note what William said about weight. Vso is given for gross weight. Book numbers for gross are probably ok for the lesser weights (since you are going to do runway length calcs etc.). But smart airmanship is going to factor in how the weight will affect landing distance just as William is talking about.

-----------
[FAA's "On Landings Part II"]
For airplanes without a table of approach speeds as a function of reduced weight, a rule of thumb is to reduce the calibrated approach airspeed for the maximum weight of your aircraft by one-half of the percentage of the weight decrease. For example, if the airplane’s weight is 20 percent below maximum, you would decrease the approach-calibrated airspeed by one-half of that amount, or by 10 percent.

At anytime, if you happen to be carrying extra airspeed in the flare, the airplane will float; that is, it will glide from over your aim point, past the intended touchdown point, until that excess airspeed dissipates.
-----------

So we normally carry a bit of airspeed into the flare for as a safety buffer - how much based on weather conditions, runways conditions, loading, and what we are trying to accomplish. But people get carried away (adding too much), get sloppy, or plain don't care - and suffer the sort of problems William mentioned at the end of his post.

[DHenriques_]

I'm trying to figure out if I have my joystick setup wrong or I'm not a good enough pilot.

Every time I come in to land and start my flair. I start to porpoise the plane.
I give it a bit up and then it goes waaaay up real fast then I let it settle and rinse and repeat until bam on the runway.

I did manage to get a total greaser one time yesterday. So far I've got only 3 landings on it and 2 out of the 3 are terrible.

I'm using fsuipc for my joystick curves/sensitivities.. should I not be using that or have it set to zero?

thanks.

Below I pasted in a small tutorial for you. Perhaps there is something in it that might be of some assistance.
DH


“The Flare”
D. Henriques

I’ve received a few emails asking me about the flare. I thought I’d lay this out here for the general forum.

In dealing with what we like to refer to as “the flare”, let’s start off by saying that what I’m about to relate refers to light general aviation type aircraft. Landing techniques differ widely between different types of airplanes. For example, landing a military jet or a large airliner will present the pilot with a totally different scenario.
For most light GA type airplanes the following will do nicely.

Let’s assume for the sake of discussion that even before you begin your flare you have flown a decent stabilized approach that has put your aircraft over the threshold of the landing runway at an altitude of 50’AGL.
Note that we are dealing here with a normal landing. Short field and soft field landing differ slightly and are a subject for another time.

Let’s look at the objective and purpose of “the flare” .

The purpose of flaring the airplane is simply to TRANSITION IT from the approach where it is FLYING, to a touchdown on the runway. Naturally we don’t want to attempt landing any airplane while it has flying speed so what’s needed is a way to get rid of that flying speed. We do that by executing a “flare”.
Sounds easy enough but it does take a bit of technique to do it correctly.
The first thing we need is some kind of a landing reference; a “look” so to speak on how the airplane looks to us as it is positioned touching down.
We get that “look” before we take off as we line up. As we stop the airplane on the center line of the runway we simply look out the windshield forward and to the sides of the windshield. THAT LOOK is what we will see at the instant we touch down IN THIS AIRPLANE if a tail wheel airplane and if equipped with a nose wheel it will be that look PLUS a bit of nose high attitude that places the plane on the main gear with the nose wheel off the ground a few inches.
So here we are over the numbers at our final approach speed, flaps down if we have them and gear down if retractable; in other words configured for the touchdown.
Notice I said “at approach speed”. We can’t land at approach speed. We have to slow the airplane down, and it’s this “slowing down process” we call the flare.
There will be several things working on our airplane at one time as we do our flare. We will be losing airspeed and countering the loss of that airspeed with whatever back pressure AND WIND CORRECTION we need to keep the airplane about a foot off the runway.
It’s VERY IMPORTANT to know how this balance between the airplane wanting to land and us keeping it from landing works. Basically as the plane slows down to drag it develops a sink rate and starts to descend to the runway. Our job is to stop that sink rate and we do that by opposing the increasing drag that’s causing the sink rate with an increase in angle of attack on the wing (increasing lift). So gravity and drag are working to make the airplane touch down and we are opposing that by applying back pressure on the yoke. If we do all this exactly right we will are HOLDING the aircraft inches off the runway with constantly increasing back pressure until the decreasing airspeed causes the drag and gravity together to overcome our back pressure on the yoke. If we have done it all correctly and with perfect coordination, we have TRADED the back pressure we were applying for the sink rate thereby preventing the airplane from touching down until we have run out of back pressure. At that exact instant, with the yoke all the way back, the sink rate should produce touchdown of the wheels on the runway from the few inches where we were holding the airplane preventing it from landing………..and if done perfectly, this will occur just as the wing’s angle of attack reaches its maximum lift coefficient and passes over into stall at the 1g stall speed of our airplane.
It's noteworthy as well to take a short look at our visuals during the flare. Generally speaking NEVER fixate your visual cue on a specific area of the runway ahead of you. Keep your visual cue in motion scanning the runway ahead. Look at the far end and scan backwards toward the aircraft. In this way your depth perception will be aided as you land the airplane. Remember how the airplane LOOKED in the touchdown attitude. THAT is your LANDING ATTITUDE and placing the aircraft down in that attitude is the goal.
You should never be stagnant either visually or physically when flaring the airplane. Keep your control pressures moving and constant. Don't be tense and don't totally relax. Remember it's a tug of war between you and the airplane as to where the airplane will go and what it will do. YOU are in charge. Don't rush the landing. Take your time. If it looks bad, go around. There is never shame in going around.


So all a “flare” is………..is us keeping the airplane from landing until WE want it to land !
Takes practice, but once you get the hang of it you will understand how to land a light GA type airplane .
I hope this short tutorial helps the general forum.
Dudley Henriques

[DC3]

Here is my 'skilled' landing in the A2A Comanche.

There are two landings, the initial landing at the start of the tape with approach at 85 mph (74kts) and a second landing at 8:21 with approach at 75 mph (66kts). Stall speed is at 65 mph (57kts). Rule of thumb says 1.3 times dirty stall speed (flaps and gear out) which would be 86mph (75kts) but the aircraft is lightly loaded with only myself on board so I can comfortably approach at 75mph.

[youtube]http://www.youtube.com/watch?v=vmY5Twf7KVY[/youtube]

[AKar]

As I don't fly the simulator too often nowadays, it is easy to forget what were the good speeds again. I find it handy to write up a small Post-It listing up the stall speeds and approach speeds for different weights, say, 200 lbs/100 kgs apart. You can quickly calculate the stall speeds for different weights by noting the stall speed varies in square root of the gross weight, and calculate the approach speed by multiplying with 1.3 or whatever you use. Excel makes creating such "tables" a breeze.

-Esa

[ilya1502]

Rule of thumb says 1.3 times dirty stall speed

Please, don't forget you also have to apply the IAS-to-CAS correction to the stalling speed and then back to the result to get a reasonable approach speed. The proper procedure is as follows:

a) convert the indicated stalling speed to a calibrated speed, using the conversion information in the Pilot’s Operating Handbook;
b) multiply the calibrated speed by 1.3; and
c) convert this calibrated approach speed back to an indicated airspeed you can use in the cockpit.