To full flaps or not to full flaps!

This forum has been developed to discuss flight instruction/University and College programs.

Moderators: sky's the limit, sepia, Sulako, Right Seat Captain, lilfssister, North Shore

photofly
Top Poster
Top Poster
Posts: 9401
Joined: Tue Jan 18, 2011 4:47 pm
Location: Arrogant beyond mind-numbing

Re: To full flaps or not to full flaps!

Post by photofly »

"There's your problem, full flap reduces the rudder's effectiveness on that plane."
Perhaps he was thinking that at touchdown, your airspeed is minimized with full flap, therefore the rudder effectiveness is diminished. (Although on a 172 there's hardly an difference in touchdown speed between 20 degrees of flap and full flap, is there?)
---------- ADS -----------
 
Pronouns: he/him
User avatar
Beefitarian
Top Poster
Top Poster
Posts: 6552
Joined: Wed Dec 01, 2010 10:53 am
Location: A couple of meters away from others.

Post by Beefitarian »

Around 10 knots I think. Maybe this could help us figure out the relation of the flaps to the rudder.
ScurvyDog wrote:All this changes with the barn doors they put on single cessna's!
Like I said though, I've only drove tricycles why would I use my feet until I was slamming on the brakes?
---------- ADS -----------
 
iflyforpie
Top Poster
Top Poster
Posts: 8112
Joined: Tue Apr 15, 2008 12:25 pm
Location: Winterfell...

Re: To full flaps or not to full flaps!

Post by iflyforpie »

I've never had any problems with rudder authority with full flaps on Cessna 172s. With 40 degrees of flap you can crank in 45 degrees of bank and hold the nose straight if you push one of those 'foot rests' to fhe floor. :wink:

In a small Cessna, full flap every landing. If the wind is howling and I am coming in on a three degree (ugh), I'll put in 20 until short final and then put them all on, just so I am not revving the living daylights out of the engine to stay on slope. Otherwise, I will just come in more steeply.
---------- ADS -----------
 
Geez did I say that....? Or just think it....?
User avatar
Beefitarian
Top Poster
Top Poster
Posts: 6552
Joined: Wed Dec 01, 2010 10:53 am
Location: A couple of meters away from others.

Post by Beefitarian »

I did stop using flap for a while after that and my cross wind landings were better.
---------- ADS -----------
 
nightbird
Rank 4
Rank 4
Posts: 202
Joined: Tue Jan 20, 2009 4:47 pm

Re:

Post by nightbird »

Beefitarian wrote:"There's your problem, full flap reduces the rudder's effectiveness on that plane."
When you add full flaps some of the airflow that goes to the tail is deflected (high wing), hence the effectiveness reduction in the rudder. Try doing a forward-slip without flaps and full flaps and you will notice some difference. Now when it comes to landing it will only affect if you have to use full rudder.
---------- ADS -----------
 
User avatar
Beefitarian
Top Poster
Top Poster
Posts: 6552
Joined: Wed Dec 01, 2010 10:53 am
Location: A couple of meters away from others.

Re: Re:

Post by Beefitarian »

nightbird wrote:
Beefitarian wrote:"There's your problem, full flap reduces the rudder's effectiveness on that plane."
When you add full flaps some of the airflow that goes to the tail is deflected (high wing), hence the effectiveness reduction in the rudder. Try doing a forward-slip without flaps and full flaps and you will notice some difference. Now when it comes to landing it will only affect if you have to use full rudder.
I did and that is pretty much how I remember it.
---------- ADS -----------
 
fish4life
Rank 10
Rank 10
Posts: 2007
Joined: Sun Jun 27, 2010 6:32 am

Re: To full flaps or not to full flaps!

Post by fish4life »

keep in mind once the aircraft start to get a bit larger if you don't use full flap you run a greater risk of tail strikes... Hell we have a older 150 with the swept tail (no rear window) and if you flare too much without flaps you'll tail strike
---------- ADS -----------
 
User avatar
Beefitarian
Top Poster
Top Poster
Posts: 6552
Joined: Wed Dec 01, 2010 10:53 am
Location: A couple of meters away from others.

Post by Beefitarian »

I've never done it but I noticed during the walk around someone's dragging the eyebolt or whatever's on the back of lots of 172s I've flown.
---------- ADS -----------
 
User avatar
burhead1
Rank 7
Rank 7
Posts: 603
Joined: Mon Jun 01, 2009 4:30 pm
Location: kinda north
Contact:

Re:

Post by burhead1 »

Beefitarian wrote:I've never done it but I noticed during the walk around someone's dragging the eyebolt or whatever's on the back of lots of 172s I've flown.
Shhh it was Me :)
---------- ADS -----------
 
User avatar
Beefitarian
Top Poster
Top Poster
Posts: 6552
Joined: Wed Dec 01, 2010 10:53 am
Location: A couple of meters away from others.

Post by Beefitarian »

It's ok bur, that's why they use an eyebolt or that little aluminum angle bracket to protect the tail.
---------- ADS -----------
 
Big Pistons Forever
Top Poster
Top Poster
Posts: 5468
Joined: Wed Feb 18, 2004 7:17 pm
Location: West Coast

Re: To full flaps or not to full flaps!

Post by Big Pistons Forever »

I hate "one size fits all pronouncements" of the right way to do something, like "always land with full flap". The amount of flap I use is appropriate to the aircraft and the conditions. Little airplanes with big flaps, like the single Cessna's all seem to do better with less flap in strong crosswinds. Little airplanes with small flaps like Grummans do better with full flaps under all conditions. Heavier aircraft like the Pa31, work fine with full flaps, although 400 series Cessna's can be a bit easier to handle with less than full flaps, if you have a long runway. Transport catagory aircraft are landed with the flap specified in the AFM for the runway length.
---------- ADS -----------
 
User avatar
skybaron
Rank 4
Rank 4
Posts: 242
Joined: Fri Feb 20, 2004 2:46 pm
Location: Hotel De Glace

Re: To full flaps or not to full flaps!

Post by skybaron »

Cat Driver wrote:
I've never used full flap with the beav.


You have never used full flaps on a Beaver?

Do you fly one for a living?

Try using full flap in high winds with a STOL wing and you will think harder the next time you pump them all the way down.
Using full flaps in a Beaver in high winds would be poor judgment making for sure, but the airplane was designed and approved for the flap range available, therefore it is safe to use full flap if needed.

From the DHC-2 AFM:

"Full Flap is only required for emergency landing in very restricted areas".

Then:

Minimum run landings may be necessary under EXDRAORDINARY circumstances.

"pilots familiar with the aircraft and experienced in short landing technique may perform minimum run landings by using full flap & reducing airspeed on the final approach to 65-68mph & maintaining that speed to the point of flare out"

+1 on one size doesn't fit all.
---------- ADS -----------
 
User avatar
Cat Driver
Top Poster
Top Poster
Posts: 18921
Joined: Sun Feb 15, 2004 8:31 pm

Re: To full flaps or not to full flaps!

Post by Cat Driver »

From the DHC-2 AFM:

"Full Flap is only required for emergency landing in very restricted areas".

Then:

Minimum run landings may be necessary under EXDRAORDINARY circumstances.

"pilots familiar with the aircraft and experienced in short landing technique may perform minimum run landings by using full flap & reducing airspeed on the final approach to 65-68mph & maintaining that speed to the point of flare out"

+1 on one size doesn't fit all.

I am not sure what you mean by :

" +1 on one size doesn't fit all. "

The AFM clearly outlines the operating limitations therefore a pilot must be proficient in full flap landings...correct?

In other words a proficient pilot is one who can operate the airplane throughout it's complete flight envelope when and if needed.
---------- ADS -----------
 
The hardest thing about flying is knowing when to say no


After over a half a century of flying no one ever died because of my decision not to fly.
DHCdriver
Rank 4
Rank 4
Posts: 277
Joined: Wed Mar 10, 2010 2:56 pm

Re: To full flaps or not to full flaps!

Post by DHCdriver »

Cat Driver wrote:
From the DHC-2 AFM:

"Full Flap is only required for emergency landing in very restricted areas".

Then:

Minimum run landings may be necessary under EXDRAORDINARY circumstances.

"pilots familiar with the aircraft and experienced in short landing technique may perform minimum run landings by using full flap & reducing airspeed on the final approach to 65-68mph & maintaining that speed to the point of flare out"

+1 on one size doesn't fit all.

I am not sure what you mean by :

" +1 on one size doesn't fit all. "

The AFM clearly outlines the operating limitations therefore a pilot must be proficient in full flap landings...correct?

In other words a proficient pilot is one who can operate the airplane throughout it's complete flight envelope when and if needed.
:P I agree 100% Cat.
---------- ADS -----------
 
ScurvyDog
Rank 2
Rank 2
Posts: 88
Joined: Thu Apr 08, 2004 8:26 am

Re: To full flaps or not to full flaps!

Post by ScurvyDog »

I thought the question was about a PA31. It's really cool how the threads on Avcanada degrade to an arguement about flaps on a beaver!
---------- ADS -----------
 
DHCdriver
Rank 4
Rank 4
Posts: 277
Joined: Wed Mar 10, 2010 2:56 pm

Re: To full flaps or not to full flaps!

Post by DHCdriver »

O.K. enough with the beav and back to the Ho people. :goodman:
---------- ADS -----------
 
User avatar
skybaron
Rank 4
Rank 4
Posts: 242
Joined: Fri Feb 20, 2004 2:46 pm
Location: Hotel De Glace

Re: To full flaps or not to full flaps!

Post by skybaron »

Cat Driver wrote: I am not sure what you mean by :

" +1 on one size doesn't fit all. "

The AFM clearly outlines the operating limitations therefore a pilot must be proficient in full flap landings...correct?

In other words a proficient pilot is one who can operate the airplane throughout it's complete flight envelope when and if needed.
Sigh.
I quoted the AFM to bring to your attention that a full flap landing with the DHC2 is not something normally carried out while approaching to land. Should one have experience, and be comfortable with a full flap landing? Of course! Without question.

Would I elect to use full flap on the -2 for every landing? Hell no. Too aggressive of a pitch down attitude, descent rate, and finally coupled with (most important IMHO) the time its going to take for me to raise those barn doors to takeoff setting on a balked approach / overshoot scenario. In the end, I'm guessing because of these reasons and many more, DHC decided to have a "landing flap" setting (one notch before full flapper).

Hence "one size doesn't fit all".
---------- ADS -----------
 
Hedley
Top Poster
Top Poster
Posts: 10430
Joined: Thu May 27, 2004 6:40 am
Location: CYSH
Contact:

Re: To full flaps or not to full flaps!

Post by Hedley »

When it comes to full flap discussions, I'm surprised no one has mentioned the C150 with it's 40 flap and the later C152 with 30 flap.

Many years ago, on the odd rare occasion, I would demonstrate 60 degrees of flaps on a buck fifty. Yes, 60, no typo. Fly a circuit but don't descend on final. Maintain 500 feet until the runway numbers disappear under the nose.

Apply 40 flap, nose down, and push open both doors all the way. Seriously. Cessnas do one thing well, and that's descend. Each door might be roughly equivalent to another 10 degrees of flaps. Or not. I dunno. Anyways, with 40 flap and both doors pushed open, you can pretty well hold a vertical downline above the runway numbers and the speed won't climb much with all that junk hung out in the breeze. As you enter the flare, close both doors and land.

I think it's safe to mention, now that he's retired, that a Transport Canada Inspector taught me about 60 degrees of flaps on a buck fifty, all those decades ago :wink:



This video has absolutely nothing to do with flaps or even aviation for that matter, but I kind of like the acoustic guitar playing at the beginning.
---------- ADS -----------
 
fish4life
Rank 10
Rank 10
Posts: 2007
Joined: Sun Jun 27, 2010 6:32 am

Re: To full flaps or not to full flaps!

Post by fish4life »

The same 150 I was talking about earlier that will almost have you strike the tail if you don't use flaps was one of the early ones equipped with 40 flap... That setting is for the most part too much flap for day to day flying, if I remember correctly it was about 2100rpm to maintain 500fpm decent and 65-70kts
---------- ADS -----------
 
ScurvyDog
Rank 2
Rank 2
Posts: 88
Joined: Thu Apr 08, 2004 8:26 am

Re: To full flaps or not to full flaps!

Post by ScurvyDog »

I heard when flying the Wright Flyer, all landings are done flap less. Any one know what flaps to use the Spruce Goose?
---------- ADS -----------
 
Post Reply

Return to “Flight Training”