When do you NOT use flaps landing?

[rv8ch]

Originally Posted by rv699jb

Using extremes makes it easier to see sometimes.

Imagine an airplane that lands at two hundred, versus one that lands at twenty. We have a twenty mile per hour crosswind. The two hundred m.p.h. plane goes forward 200 units for every 20 sideways, while the twenty m.p.h. plane goes 20 forward and twenty sideways.

So, the angle the plane crabs while flying to maintain a track over the runway is different. The twenty m.p.h. plane is in a 45 degree crab. The 200 m.p.h. plane less than ten degree crab. To land, we transition from a crab to a slip by using rudder to push the nose to align with the direction of runway, so the tires are parallel with the direction we need to be going to land.

The 200 airplane needs very little rudder imput to accomplish this. It is almost like the crosswind is non existent. The twenty m.p.h. plane takes a huge amount of rudder, and may not even have enough rudder imput to swing the nose that far!

If we could have a way to just change the 20 m.p.h. airplane into a 200 m.p.h. airplane when we need that for landings.

So, the point of this is two fold. One, the faster we can land, the less crab angle we have to overcome. If we are close to a speed where we are using full rudder and we get gusts on top of it, we might not have enough control to land. So, a no flap landing raises the stall speed slightly to allow us to touch down faster with less crab angle to remove with rudder!

This is the control our airplane has to make it closer to the 200 m.p.h. plane. Secondly, the faster we go, the more force a deflected control has for a given imput. If we can land faster (stall at higher speed), the rudder won't need as much deflection to align the nose to the direction of travel necessary to land as it would at a slower speed. We have more control reserve, so to speak, at higher landing speeds!

The rudder works on a lever arm back from the center of gravity of the plane. If you can make the plane land faster, less rudder imput is necessary for the force required to align the airplanes with the runway, and less change of angle is required too.

If you move the center of gravity forward, your rudder has more authority too, because you lengthen the lever arm (another discussion)!

Now, one last thing: remember, lift causes drag. After touchdown, the airplane still wants to weathervane towards the wind. Let's say we have a right crosswind. The plane wants to turn right. As we slow, the rudder runs out of enough force to keep the plane aligned with the runway. The plane is still light on the tires, so brakes don't work well either.

If only we could have some way to pull backwards on the left wing till we get a little slower and the tires have enough friction to grip! We do, but most pilots quit flying after touchdown. Roll the ailerons full stop towards the wind after touching down.

In this situation, the left aileron is down, causing lift and also drag. More drag on the left wing is free help to keep us aligned with the direction we want to go and not the way the cross wind wants us to weathervane and go! It is like giving the full left rudder we are holding just a little boost!

Just some thoughts I hadn't seen up to this point..

jimmyB
RV-6

Very interesting points, Jimmy. I've always read "climb into, dive away from" when it comes to how to hold the controls when on the ground. That matches your suggestion.

[David-aviator]

Originally Posted by lr172

A question for the experts. I fly my 6A from a field where most strong winds are 80-90* crosswinds from the South. There are a bunch of buildings and trees on the south side of the field that are about 100 yards away and for the whole length of the runway. I get a lot of unpleasant gusting, rotors, etc. When the winds are gusting >20-25, I get violent sinks of 5' or so while flaring. Due to this, I have dropped my SOP from 40 -> 30* of flaps.

I am wondering, will reducing flaps further help me to better manage these situations? It is a 4000' runway, so I have plenty of room to work with.

Thanks,

Larry

I had same experience at former home, Troy Airpark, one day with gusty cross wind. Sink at about 100' was very noticeable and with 40 could not control it, made go around several times. Finally tried it with 20 flaps and was able to fly through the sink and manage a landing.

[N941WR]

Originally Posted by kstone

Interesting discussion. I've had my (bought) -7A less than a year, but my experience is that flaps on my plane add very little lift, mainly just drag. When going from no flaps to full flaps, the plane does not required any trimming, which tells me there's little additional lift. I always use full flaps landing except in strong, gusty crosswinds, because the drag from the flaps combined with the flat CS prop are like putting on speed brakes during the flare and floating is negligible, even at the fairly high approach speeds I use.

The OP was asking about landing his RV-9, which is significantly different than your RV-7A. The -9 with its high lift / aspect ratio wing and follower flaps is significantly different than a -7(A).

As you read these replies, pay attention to the airplane listed in the signature sector the commentators.

With the -9, you want drag and must nail the approach speed (especially with a FP prop).

[rvbuilder2002]

Originally Posted by N941WR

The OP was asking about landing his RV-9, which is significantly different than your RV-7A. The -9 with its high lift / aspect ratio wing and follower flaps is significantly different than a -7(A).

As you read these replies, pay attention to the airplane listed in the signature sector the commentators.

With the -9, you want drag and must nail the approach speed (especially with a FP prop).

In the interest of clarity regarding details of the RV-9, it doesn't have follower (or fowler) flaps. It has slotted flaps.
Fowler flaps deploy on a track system (think Cessna) that moves the flaps aft for an increase in wing area before they actually start to deflect much.

I do agree with the rest though......

[6 Gun]

This has been a very good read and enjoyable.Here is my short take away from this learning. There are many types of pilots and many different ways of landing said airplane and a factor is how many people are watching , the more people the better chance of screwing up like at a fly-in I know that's in the back of your mind and no one said anything about it. The other main factor is every landing is different ! As guy who flew a champ for 33 years and all the Cessnas and high performance twins that came over the fence at 125 mph and Stearmans I can say an RV is one of the easy airplanes to land I have ever flown.My RV6 is very forgiving I have my trim set for cruise and never touch it unless its to adjust for different weight in cruise.One day I may build a new left elevator with no trim tab and use a spring system like the aileron .Now anybody that's having a problem landing cover up your airspeed and let the stick tell you how fast your landing no need to look at airspeed after the flaps are down on final.Pick a point on runway and try to land on it every time.Its like the old cropduster told me (you cant use runway behind you.)
Bob

[Pmerems]

Several posts here talk about coming over the fence below ## kts and anything below that it "Sinks like a rock (SLAR)".

What is missing from the general statement is if at idle power or not, solo or gross weight. CS or FP prop is also a factor in this statement.

My RV7A (CS prop) SLAR below a certain airspeed with full flaps at idle power but if I carry a little power I can land slower. I typically pull the power back to idle once over the numbers so I never let the speed drop below my "SLAR" speed until I am only a foot or two over the runway.

It would interesting to note the what SLAR speeds at idle the previous posters are experiencing.

[RVbySDI]

As Bill eluded to, there is a considerable difference between the performance of the 9 compared to the 6,7,8. Exceedingly so if it has a fixed pitched prop. The 9, whether little wheel on the tail or nose, does not 'drop like a rock' at idle. Slowing a fixed pitched prop 9 down takes quite a bit of planning and execution. I would say that slowing the plane down was the most difficult part of learning how to fly my 9A. Get the speeds right and it will land itself. Too fast, you will never land. Too slow, well, the only too slow is below stall. Get below stall and it does come down like every other bird, but then, who wants to get below stall before the wheels touchdown?

Live Long and Prosper!

[FLY6]

A).

As you read these replies, pay attention to the airplane listed in the signature sector the commentators

Not sure how to highlight the quote from a previous post but the above was said. I think it is nice when people put their aircraft type in their actual post. I have had times when I read a question, saw no aircraft type, looked at the signature and still did not know the aircraft type. I think it is a good habit to mention the aircraft type in the post so everybody knows what the real question is.

[N941WR]

Originally Posted by rvbuilder2002

In the interest of clarity regarding details of the RV-9, it doesn't have follower (or fowler) flaps. It has slotted flaps.
Fowler flaps deploy on a track system (think Cessna) that moves the flaps aft for an increase in wing area before they actually start to deflect much.

I do agree with the rest though......

Thank you for correcting me Scott! Much appreciated.

[RVbySDI]

Originally Posted by FLY6

A).

As you read these replies, pay attention to the airplane listed in the signature sector the commentators

Not sure how to highlight the quote from a previous post but the above was said. I think it is nice when people put their aircraft type in their actual post. I have had times when I read a question, saw no aircraft type, looked at the signature and still did not know the aircraft type. I think it is a good habit to mention the aircraft type in the post so everybody knows what the real question is.

thanks for the suggestion. I have made the change to my signature.

Also, as an FYI, there are a few ways to quote something. If you wish to quote the entire post just click on the word QUOTE at the bottom of that person's post. If you want to quote more than one post click on the quotation marks at the bottom of their post until the last person you wish to quote. Then on that last one click on the word QUOTE. IF you only want to quote part of what they said just delete the words out from between the QUOTE tags. Or, you can cut and paste words in a quote by copying them then clicking on the 'quote' button above your post in the toolbars. It is the button that looks like a little cartoon QUOTE bubble with words in it.