Are Flaps Over Rated?

[Erik]

I've got the stock 2 notches of flaps (25 and 50 degrees?) and I'm thinking about adding a notch between no flaps/first notch (10 degrees?) after reading this thread: http://www.supercub.org/phpbb2/viewtopic.php?t=2871&highlight=flap+notch

So far, Iamb not that impressed with what flaps have been doing for me. This is especially interesting since people talk about flaps like they are the best thing going in aviation. Now, mind you, I am a 200 hour pilot (40 hours in Super Cub), and I'm still experimenting with lots of things before coming to final conclusions. I've also gotten proficient enough so that I am landing on 600 ft bush strips, gravel bars, and ridge tops. That is the emphasis in my flying. These are my impressions so far:

1. Slips are wonderful maneuvers and can be used very effectively with no flaps to full flaps, at any height, to develop a good sink rate and not gain airspeed. Some people are afraid of slips or state they should not be combined with flaps, but I don't seem to agree with that so far.

2. PA-18's seem to float and have a shallow glide slope. When on final and trying to drop down without gaining airspeed (i.e. after clearing obstacles), it seems more difficult than when I was flying a Cessna 140. If I want a better sink rate, would it be better to use full flaps (i.e more drag than lift effect) or no flaps (i.e. less lift than with flaps so maybe a better sink rate) - and/or slip to adjust. I'm convinced "diving for the runway" is bad manners. I don't have a VSI, so it's a little bit of guess work right now on sink rates.

3. Flaps effect pitch, and I think this might have a poor effect on round-out in a flare. Would you use full flaps or 1/2 flaps in a tight landing spot?

4. Seems everyone says to start the take-off roll with 1/2 notch of flaps. Why is that? I have not been successful in forcing it to fly before it was ready (at the appropriate forward speed). So wouldn't it be better to leave the flaps off (stay clean) for as long as possible in a short take-off? Then maybe pull flaps to jump up into ground effect. For purely soft field stuff, it seems much more straight forward - simply leave full flap on.

Response from experienced STOL guys/gals appreciated!

Thanks, Erik

P.S. - this is not STOL, but why deploy flaps for slow flightseeing/cruising. They may allow for a slightly slower airspeed (say 45 instead of 40), but you will be in the 60 to 80 mph range for this type of flying and what good will flaps do at those airspeeds? Why not just trim for the airspeed and power to maintain the altitude. I started deploying flaps for this purpose because I noticed others doing it/talking about it. But then I thought "what's the point here with the flaps?"

 

[mvivion]

Erik,

One thing you seem to have missed: Flaps lower stall speed. Now, you may argue that, yes, but the J-3 has the same stall speed as the Super Cub, but that is primarily a function of weight, and stall speed as advertised is always tested at max legal weight (except by the Mountain Goat guys :lol: ).

So, in response to your comments/questions:

1. Slips are a great maneuver, but harder to manage, particularly in a tough spot (think terrain/trees/turbulence) than flaps. There is no prohibition that I'm aware of on using a slip AND flaps on the Cub, though there is in other aircraft. But, don't be stupid: try it at altitude first. You can develop an enthusiastic descent rate.

2. You are right: "diving to a runway" will cause severe float. Full flaps and a properly managed airspeed on the approach will resolve float issues. You shouldn't be doing any landings into actual short fields till you really have mastered managing airspeed and energy on approach at a major landing spot, as in airport.

3. Full Flaps. This gives you maximum drag, and you can work drag against power to manage your descent and touchdown point. Flaps also provide an added benefit by changing your attitude prior to landing. With flaps down, the airplane is more nose down, permitting you to see better. One of the things a lot of Cub guys don't like about the Husky is that you have to get the nose up on short final to slow down adequately. This requires a bit of a side slip right up to touch to enable you to see where you're about to land.

4. See my first note. Flaps lower stall speed. That is one of their two primary jobs. Why would you even think of trying to takeoff with a higher stall speed? Half flaps for takeoff. Set them prior to coming up with the power, or some folks prefer to pull them on just prior to liftoff. Either way works fine, but if you deploy flaps on the run, you really need to practice that extensively, cause a bobble here will slow you down appreciably. As far as soft field stuff, the first notch of flaps in the cub provides a lot of lift, and a significant reduction in stall speed. Full flaps mostly adds a lot of drag. For all takeoffs in Cubs, I use half flaps.

I see no particular point in adding another notch in your flap selector, but if it makes you happy, go for it.

Those are some of my thoughts. Hack em up, Boys and Girls....... 8)

MTV

 

[bearsnack]

I had an Aeronca Sedan for a while. The absence of flaps made me very proficient at slips. It also made me want an airplane with flaps.
To me a bushplane without flaps is operating at a much lower efficiency than possible.

 

[bob turner]

Flaps make for shorter ground rolls, all else being equal. In a lightplane, that's about all they do - but you should stabilize your approach with landing flaps set long before the flare. Try 50mph. full flaps, for starters.

Flaps are, in my opinion, the most over-used, under-understood things on a lightplane. Some think that they make you climb better (or faster) due to increased lift. When I say they don't, I get spirited arguments, but no math. When I pull out the math, eyes glaze over.

One vaunted aviation publication printed a letter - a Beechcraft departed a high/ hot airport with lots of weight. All aboard died. Letter-writer said that if they had just extended more flaps, they would have made it. Magazine never corrected that. Check with any aero engineer on that one.

 

[ag-pilot]

flaps

Eric, The notch of flaps most people file into a S-cub is used mostly to alleviate trimming when going from a medium cruise setting of say 2350 and 80mph to 2000-2100 and 60mph without re-trimming. That first {10-15 degree} notch also makes the plane way more stable in a turn. When spraying with a heavy super cub normal operation would be to pull up at the end of the run, make your down wind turn then pull the first notch of flaps to complete the turn letting them off when you are diving back into the field. That first notch of flaps would tighten you turn and releave some of the back pressure.

I also agree with Mike, Do yourself a favor and find some 3000+ hr. cub pilot to show you the ropes on off-airport operations. I feel that is the only thing that saved me from busting my A$$ for the first 1000 hrs or so.
Dave

 

[Christina Young]

I thought that the prohibition on using flaps and slips at the same time was only for Cessnas with the swept tail?

 

[Erik]

I agree flaps allow for a slower stall speed.

I agree stall speed increases with weight.

I flew 10 hours with Jay of Alaska Cub Training Specialists this summer (bush flying/mountain flying course - Christina and Steve have also flown with him). One of the best things I got from that experience is to trust ALL the maneuvers of the plane and to always fly the plane as needed at any given time. I contrast this with so many times when someone has told me I am wrong when it is they who are wrong/ignorant because they are set in their ways and inflexible in their flying habits (i.ae. "don't slip with flaps on", "don't bank so tight", "don't use wheel landings", "you have to fly a standard pattern" - even though its a bush landing site, etc...).

I like the idea of pulling 10 degrees of flaps for turns as a "re-trimming" method.

There are lots of long bush strips that would provide better practice sites than the airport. I only use airports to practice pattern and radio work.

Thanks, Erik

 

[Jr.CubBuilder]

This is an interesting thread to me because I'm not much farther along in experience than Erik, and I've been learning more about how my plane reacts with the flaps also.

MTV you have vastly more experience than me, however so did the test pilots that worked up the numbers for my flight manual half a century ago and they specifically indicate that once over about 5000' DA the use of flaps on takeoff results in a greater distance to clear the 50' obstacle due to drag. I believe you have a C170, so I'm curious to hear what you think about that issue, and I'm not intending any sarcasm here either.


[/quote]

 

[pzinck]

I dont know how short you can land a supercub without flaps.I will say that on the big cessnas there are lots of places i wouldnt land or even try without flaps.They sure as heck help me to reduce approach speed as well as cushion my plane with its reunion with the earth.I have seen some other guys land real short without flaps,but i was never real good at it.All the cubs i have owned have had factory flaps.An easy test is to go up and do slow flight and stalls with and without flaps.All of the birds i have flown fly much slower with flaps dirty.P.S. Erik some of these things you question are interesting discussions.

 

[CubCouper]

Erik,

There is a huge amount of knowledge and information on this site that you have no doubt discovered. A few years ago I was 450 hour pilot (nearly past that first magic 300-500 hour block that I was told was the most dangerous)I was a good pilot, my instructors told me so. I had 80 hours in my SuperCub and felt I really go anywhere-do anything in it that I could in a 182. A light (ok 15G20) crosswind that would have been a piece of cake in the 182 taught me how much I didn't know in about 7 seconds. Eight months I got my plane back with a new wing and a whole new respect for EVERY aspect of flying the cubs. Watch those ol' codgers and do what they do. Ask why. Get them to demonstrate. In a safe environment, try it both ways several times, then decide. I used to use flaps occasionally when I remembered. Now I'm mostly religious about treating every landing like a short-field, soft-field, emergency the flaps are carefully thought though and applied as necessary on each and every approach.

 

[ground loop]

Erik,
Try it all, don't just trust the experts. In your hands, with your airplane, things might work different (what works for a professional pilot, doesn't work with a neophyte like me. Also, changing the airplane has made me change technique).

It might be a good time for some guru to explain the theoretical differences between flap types (Fowler,etc.).

 

[bob turner]

15G20 is a challenge for any taildragger pilot. I challlenge myself with that sort of thing very close to home, so I can walk back to the hangar with the pieces ( I have spare everything except cabane vee). So far I have survived, but that is a whole lot of crosswind for any of us!

 

[Aviator]

..."don't slip with flaps on", "don't bank so tight", "don't use wheel landings", "you have to fly a standard pattern" - even though its a bush landing site, etc...

Erik,

Pilots before you (and me) paid for such do's and dont's, so don't discount them so quickly. They're yours to use for free. It's been said, rules exist for the guidance of the wise and the protection of fools. But there's more to it: they help turn low-time pilots into high-time pilots. Deviate from a rule if you see fit, but before you do, find out its cost. Fly safe !

 

[Fortysix12]

Flaps are not overrated.

 

[ground loop]

Flaps are so good that some guys buy wing that have them extended!

 

[bob turner]

I love flaps! I was one of the few guys who insisted on using flaps 40 for just about every landing in the 737. Boeing said "use max flaps consistent with conditions" or something like that. I think noise and maybe fuel were the drivers for a flaps 30 standard.

I note that Cessna, in their wisdom, restricted those beautiful slotted flaps to 30 degrees, and that the Husky flaps, while effective, could have been spectacular with a 40 or 50 degree position. The C-180 is actually more fun at flaps 40 than a Super Cub is at flaps 50!

That said, I still say that flaps are misunderstood widely in the light plane community, and grossly mis-used in the climbing phases of flight.

 

[sj]

That said, I still say that flaps are misunderstood widely in the light plane community, and grossly mis-used in the climbing phases of flight.

Bob, you are right on there. While they may shorten the ground roll somewhat, you will climb slower - albeit at a better angle (usually) and the tradeoff in my experience is equal in the end.

On the C-170, if you climb out with any flaps and don't pick up some speed, when you dump them you mush right back down to where you were (or so it feels).

One fine day, I flew 4CC out to the practice area and slipped and stalled and turned and stalled in every configuration I could think of. The belly tank is placarded against spins, or I would have played with them too, but instead just worked on incipient spins. With VG's, the full stall slips I was doing were perfectly docile with no suprise even when I uncordinated it back and forth regulary. I would NEVER do this to land, because you don't really want a 5000FPM rate of descent (exaggeration) to do a nice stabilized landing and since you are already essentially stalled, you would not have anything left to flare. I know of no restrictions on slipping cubs with flaps, but there are a lot of things I don't know... IF YOU ARE GOING TO DO ANY OF THESE THINGS, BE SURE TO TAKE AN INSTRUCTOR KNOWLEDGABLE WITH SPIN RECOVERIES WITH YOU, OR AT LEAST SOMEBODY WHO PLAYS ONE ON TV.

While it is technically true that you are flying a little slower with the flaps deployed, the biggest change is the angle of descent you can acheive with flaps that is hard (without a wild banshee slip) to get in a flapless plane. This enables you to clear obsticles, but still land in a relatively short space.

There are lots and lots of pilots out there whose understanding of why to use flaps is "because they are there".

sj

 

[ground loop]

Steve,
If you have the BLR kit, fully cross control and do level wing 180 degree and 360 degree turns with half and full flaps. It is a real hoot. The BLR guys told me to do it. At over 2000 lbs it will stall and fly right through the stall. It also gives you another way of appreciating what the flaps can do.

 

[sj]

Although I did not hear it from them, I definitley did that as part of my series. It is tough to get the thing to go squirlley on you.

Frankly I personally think the Micro VGs are even more stable than the BLR's that I have now, but that is just a lay person observance on the different planes I have flown, not any kind of technical facts. They both work great.

sj

 

[Tim]

I don't have flaps on my 2+2, I have spoilers. If I had it to do over again I'd have flaps. I just put VGs on and can get in with the average supercub with flaps ( not with you experts in AK.), but getting out is a different story. There are places around here I know I could get in, and I want to, but I'd have to take the wings off and truck it out. Flaps are not over rated. On our type airplane I think It makes a 100ft difference on ground roll.

 

[PA-18]

Hello Eric,

I think the point of your first notch in the slowed down mode of say 60mph is purely margin of saftey. All are different but in your plane just slow down from cruise to stay 65 and give it two turns of nose down and power as needed. This is a real good place to keep your supercub. They will fly slower than this but lots of variables start sliping in that you just need to experience for yourself in your plane. This will let you experience them from a safe place. I dont have much experience from high altitude places but I have flown mine on alot of windy hot days here on the Tx. coast and there are days it flys like a supercub and others the air is just bad. I have a BLR kit on mine since it was rebuilt and like the way it handles now better. I also believe the need for a notch of flaps is to increase wing area and get you more lift and keep you farther from the stall while you are banking and circling around. If its there you might as well use it for safteys sake. The next notch drag starts to outway the lift. The way I see it one notch for keeping you in the air slow and safe and the full notch for bringing you down out of it slow and safe. The extra notches you here guys file in are for people who must wring alot more out of them than I want to. Good Luck!!

 

[diggler]

Ixx

 

[bob turner]

Steve - on the subject of "best angle" - most POHs today will state somewhere that best angle is flaps up. The thing that is misleading is the short-field, close-in obstacle is usually best handled with flaps, since you get off the runway so much sooner. The loss in climb performance is not as significant when the obstacle is a 50' tree.

The Super Cub book does say that best angle is with full flaps. I tried that; it is exhilarating! The aircraft seems to go straight up! Airspeed said zero. Zero! An engine failure at that point would have taxed my ability.

The C-180 books (at least some of them) say to clear an obstacle use flaps up. However, they give a flaps 20 Vx of around 60 mph. I tried that too, and the deck angle is quite impressive! A climb at 70 clean is very impressive as well, and I think survivable if the engine seized.

Anyway, the equations indicate that if you can stay aloft with flaps zero at any given airspeed, then climb angle will be greater with lesser flaps. The only time increased flaps increases the climb angle is when speeds are less than those required for climb clean. My opinion, but based on conversations with some real heavies. The equations can be found in the NavWeps publication on aerodynamics.

 

[T.J.]

I'm a sick man. I again agree with Dig!
I need to go to some kind of counciling I guess. I reckon it is the Old Age thing.
Absolutely, one notch of flaps lets you fly slower with the tail higher.

 

[mvivion]

There are a lot of places where a bit of flaps, particularly in a heavily loaded airplane, provide a "leveling" effect, and help the plane actually fly a bit more elegantly, if not faster. A prime example is the Beaver with a big load on amphibious floats. Crank on a tad of flaps to level the airplane, and its a whole differnet airplane. The Wip 206 at 3800 pounds ditto. Nothing wrong with using the tools they gave you.

A note on Piper's version of best angle: I do think it probably is the best angle procedure (45 mph and full flaps), but as noted by another poster, the airplane will stall like instantly at that attitude if the engine coughs on you. So, take care of your motor, and don't use best angle unless you no joke really, really need it. As in trees in the TOP of the windshield.

I have very little experience at DA's of greater than 5,000 feet. That said, I've worked a LOT of heavy Cubs, in the restricted category, and at some warm temps, and I still feel that takeoff is best with half flaps. I ALWAYS get rid of the flaps, though, unless I'm looking at serious obstacles to get over. I do believe that at high DA, the plane will probably climb better with no flaps.

Piper did the testing though, so don't discount things too quickly, based on some knob like me suggesting this is the best way to do things.

Best angle for a helicopter is straight up, simply because forward speed is zero. The reason the Cub's best angle is full flaps and 45, I'm betting, is simply cause you aren't covering much ground whilst going up. You aren't going up at the same rate you could in a different configuration, but remember, best angle is most height for a given distance over the ground.

As with any of this stuff, get with an instructor, and practice, practice, etc, close to home prior to going into no joke short strips.

But, as several people pointed out, flaps are worth a lot.

The C-170 takes off much shorter with flaps, but climbs much better without flaps, in my opinion. That said, my airplane has an O-360 and a big prop, so none of the factory numbers really mean much. Its all up to the user to decide what works best, cause there are no "factory numbers".

MTV

 

[sj]

If I remember the little bit of aerodynamics we learned to be instructors, what Dig and MV are talking about is that when flaps are applied the center of lift moves backwards on the wing, more or less depending on the flaps.

I agree putting around with you 150HP guys with 35 degree fixed pitch props I have a knotch of flaps on all the time to keep the plane level...

Some people would say that flaps help you attain slow speed with a nose low attitidue (The 170 REALLY demonstrates this well in my opinion), and this is a nice side effect of allowing you to have a steeper angle of descent and maintain a lower airspeed.

If you are having trouble 3 pointing with big tundra tires because your mains are on before your tail, try a notch or two less flaps and see what happens.

sj

 

[cubdrvr]

I recently switched my flap control bracket from 3 notches to 2 notches. I've found it to be simpler and actually like the 1st notch ( 20-25 degrees?) better than the old one of 10 degrees for slow flying. It pitches the nose down for better forward visibility and I can run level around 50-55 mph at 2000rpm all while being very maneuverable. I've played with a steep descent rate AT ALTITUDE by holding the stick in my lap(full flaps, no power up to 1500 rpm).......I get pretty much a mushy descent with an occasional small break of the nose. I'd like to try this as a landing technique sometime by lowering the nose and adding power just prior to touchdown but, so far, haven't a big enuf pair to try it.......

FLAPS

 

[S2D]

I use 10 degrees flying around slow because it helps lift the tail up.

I use the flaps a lot cause I am too lazy to retrim when I change power settings.

 

[375handh]

Mike:

Best angle for a helicopter is straight up, simply because forward speed is zero.

I really appreciate your Super Cub comments and wisdom, but you are way off on the helicopter. Best angle of climb on the helicopter is above ETL (Effective Translational Lift), which is usually reached at about 15 to 20 knots (depending upon the size, blade area and RPM of the rotor system). At this point the rotor completely outruns the recirculation of old vortexes, and begins to work in relatively clean air, much more efficiently. The best angle of climb on a Schweizer 300CBi is 63 KIAS, for example.

Every helicopter has a height velocity diagram (also known as the Dead Man's Curve).

The purpose of the height velocity diagram is to determine the airspeeds and altitudes where the average pilot can safely execute an autorotation in the event of a power failure. In general, it is safe to be at zero forward speed within say five feet of the ground or at 500 feet AGL, but at say 200 feet you had better have some serious forward speed and skill or you will never get into autorotation if the engine coughs.

That said, there are lots of helicopter pilots that fly within the shaded area of the height velocity diagram, particularly everyone doing external load operations. And, of course, you can take a helicopter straight up if you have enough power. But in either case, if you lose an engine, you are going to crash, not autorotate to a landing. Just like cubdrvr, so far I "haven't a big enuf pair to try" operating inside the height velocity diagram.

375handh

 

[Fortysix12]

Does the pilot who works for -I think Alaska Airlines and owns a 180 hang at our sight. He was featured in a Bush flying segment on the Discovery Channel some time back. He routinly flies a 737 into and out of what I remember to a 3600 ft strip. Would like to hear what that professional bush pilot has to say.