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Flaps on take-off

uk_figs

uk_figs

Well Known Member
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Just finished the AOPA article about the DC-9 no flap incident and wondered how many people flying the RV's use flaps on take-off as part of their normal procedure (not short field, grass etc). I do not as my 7 gets off the ground quickly and I remember the same discussion with my Pacer buddies about 15 deg flaps improving TO performance (some did some didn't).
Just wondering about the benefits in our machines.
 
I am not currently flying an RV, but I always used a couple of notches on takeoff, not because the runway was short, but primarily to reduce wear on tires and wheel bearings.
 
Take-off flaps

Larry Vetterman was visiting me a few years ago. I explained that I always use 15? of flaps on my short runway.

He made the comment, "Why on short fields only? I figure the quicker I'm off the ground, the less wear I'm putting on the tires."

Sounded good to me. I have used 15? of flap for every take-off since. Not a bad habit, I think.
A side advantage is that by developing the habit, I never "forget" to raise the flaps after a short field take-off.
 
At gross, from grass or funny fields I do as Mel does. Take off flaps as much as max elevator travels. "Forgetting" to retract that's another story :D
 
I use one notch on takeoff if i've got full tanks and a passenger. Otherwise I haven't bothered. Don't really need it, and when I forget them it's kinda embarassing... "Two, your flaps are still down..."
 
RVs stall slightly lower with ~half flap than clean. Given the high power-to-weight ratio, the extra drag of the flap I would suggest is insignificant.

So the ground roll will be lower, and (potential) initial climb angle greater. However, since RVs are such high performance, neither benefit is usually required...

I figure the quicker I'm off the ground, the less wear I'm putting on the tires
Click to expand...
I would reckon tyre wear is 90%+ caused by (often unnecessary?) braking / cornering, not a few feet extra ground roll. And I would think offset by the extra use / wear in the flap system. As also pointed out, it is pretty hard to overstress the flaps on departure if they were never used.

Whilst we do use them out of short strips, the main benefit to me is "rough surface" where the extra few knots spent in the air does mean less wear and tear on the U/C etc and occupants ;) Off long/hard runways, I tend to go flapless.

Compared to the DC-9 (and other) accidents, though, I would suggest it is only a small factor in RVs, and rarely of significance.
 
Never use flaps on our RV-6A except landing

I seem to recall that you have the manual flap system Mel. I would have also but the QB never came with them (and I did pursue it with Van's at the time - loved them on our Archer II). I never use flaps on Our RV-6A except on landing and then it is full flaps - I never use an intermediate setting.

Bob Axsom
 
interesting

I think it would be neat to start a questionnaire on this because I have been curious what people are doing too. It would be nice to know for those that do use them, what percent (1/4 or 50 %?) you use. Dave
 
I use 1/4 flaps as a minimum and use 1/2 flap if I really want to get it off the ground quick. I guess you never need the flaps for takeoff. It is just part of my pocedure and the air is much less punishing on the plane than beating down the runway at higher speeds than required. Just makes sure they are not reflexed as a minimum.
 
My testing has shown that 15° flap generates the shortest take-off roll.

And it makes sense. If you consider the design of differential ailerons, the "down" aileron on the RV is 15°. This typically generates the most ideal ratio of lift to drag. On the short wing RVs, the flap is the same chord as the aileron.

If you have electric flaps, my recommendation is to align the flaps with the "down" aileron. That will give you the shortest take-off roll.
 
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By the time I get the throttle fully in, I am airborne.........

So no flaps for me.

Unless I am doing formation with Nephew Alastair's Falco which takes ages to get airborne - then I use part power and 10 degrees flap...:rolleyes:
 
The "Flaperon Crowd" in the 12's tend to not use the flaps at all in many instances. Maybe I will decide that too, but I doubt it.
 
How Mike Seager taught me RV-7 take offs:

Soft surface: flaps equal to aileron fully deflected
Hard surface: no flaps

I suspect his plane has, by far, more takeoffs than any other RV around.

FWIW, I don't remember him simulating a hard surface, short field takeoff--for RV's is there such a thing?
 
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15 degrees at all times. keeps the nose lower and gives me something to do on take off. ever forget to put them up, never! HA HA

to flap or not to flap, that is the question. :)
 
alpinelakespilot2000 said:
FWIW, I don't remember him simulating a hard surface, short field takeoff--for RV's is there such a thing?
Click to expand...

Depends on what you call "short". Many consider my 1500', hard surface short.
Regardless, I clear the railroad by a better margin with 15? of flap.
 
Feel

I think the feel on takeoff is much nicer with flaps. Instead of having to sort of force the tail up it comes up naturally with very slight forward pressure.
 
alpinelakespilot2000 said:
How Mike Seager taught me RV-7 take offs:
Soft surface: flaps equal to aileron fully deflected
Hard surface: no flaps
Click to expand...
Works for us... Without flaps we're off in less than 500 feet. Gota love a CS prop on a 9.
On a different model, maybe a different answer.

alpinelakespilot2000 said:
short field takeoff--for RV's is there such a thing?
Click to expand...
I believe that there is... Cool morning, a bit if a breeze, 1/2 flaps, full power -> a long takeoff roll of about 150 feet :cool: That should be a RV short field takeoff :D
 
db8 said:
I think it would be neat to start a questionnaire on this because I have been curious what people are doing too. It would be nice to know for those that do use them, what percent (1/4 or 50 %?) you use. Dave
Click to expand...

As a matter of procedure I always use flaps for take off. On my RV-8A I use 50% for take off and full flaps for landing. Cessnas 1 notch or 20 degrees.
My reasoning is that the sooner that you become airborne, the better control you have over the aircraft. Runways are transition areas and impose more risk than taxi or inflight operations. Runway behind you is of no value, the sooner you can become airborne and clean up the airplane in a prudent fashion the better off you are.
Jim Wright
 
I always use about 10 degrees or so whenever I've got a passenger or otherwise loaded heavy with camping gear/baggage. I also used about 10 degrees in the RV-8 when doing formation takeoffs last summer when my retired USAF buddies were teaching me formation flying... it made the takeoffs feel more solid and aileron control more positive just after liftoff while being in such close proximity to the other RVs... which made me feel more comfortable too ;)
 
I confess that I almost never us flaps on takeoff except when there's a major Bubba in the right seat and I want altitude quickly. It's never been because the field was short. That said, I think I might start trying to get in the habit. Nothing wrong with doing it all the time and it grooves the habit of max performance. I also noticed that both the pilot who did my first flight and Van himself used partial flaps on takeoff. My first flight pilot matched the flaps to the fully deflected down aileron. They're both better pilots than me so why not emulate good models? The only time I can think of not to use flaps might be with loose gravel banging up the under side of thef flaps. Perhaps also formation takeoffs, but that is so far beyond my knowledge and abilities it's just wild speculation on my part. I'll try to modify my habits to improve them...

All Best

Jeremy Constant
 
Speed limits

I think the biggest draw back of using flaps on takeoff is not exceeding the max flap extension speed, which comes up pretty fast! For the -9/A that's only 90 mph. The more flaps you use the more "sink" you get during the retraction, something to keep in mind if there are obstructions or rising terrain.
Food for thought...
 
Flap use!

...I always use 15 deg. flaps on take off and full flaps for landing. This is my standard procedure and I only vary from this when forced to by people that are in front of me and don't understand what a traffic pattern is supposed to look like. On take off the roll is shorter, the climb is better, less wear on everything and should you need to abort the take off you are in the best possible configuration to use the least remaining runway and the lowest speeds possible. When landing I can't see leaving the airport once you are in the pattern by making some ridiculously huge pattern, or having to use power to get back to the runway and accomplish a landing. I look at every landing as if I had lost power, this way if it happens in the pattern, it's just another landing, no big deal! The speeds are reduced with full flap use, requiring less runway, shorter roll-out, less wear and tear on everything. If the runway is long, I land long and as close to my preferred turn off as possible. I have installed a flashing yellow warning light next to the flap switch that eliminates forgetting to retract them on take off as it is easy to forget sometimes when you are busy. This all makes the most sense to me, and is what I am most comfortable with. Allan...:D
 
flaps on every t/o

When the RV was done, I started out using flaps only on shortfield takeoff's.
My homebase has a 9000' RWY so I never used flaps there.

When I took off from short fields, a few times I forgot to raise the flaps after takeoff.
I didn't realize this until I did the "After T/O Checklist".
Fortunately, I didn't overspeed the flaps.

After forgetting this a couple of times, I started to use t/o flaps (full aileron deflection) on EVERY takeoff.

Since I'm now doing the SAME things during EVERY takeoff (300' AGL: flaps up, 500' AGL: set climb power) I never forget to raise the flaps.

The bonus is that if the engine quits right after t/o, the flaps are already 15* down so the time required to lower full flaps is reduced.

My 2 cents...
 
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rv9av8tr said:
I think the biggest draw back of using flaps on takeoff is not exceeding the max flap extension speed, which comes up pretty fast! For the -9/A that's only 90 mph. The more flaps you use the more "sink" you get during the retraction, something to keep in mind if there are obstructions or rising terrain.
Food for thought...
Click to expand...
And with a 9 that has a 300-400 foot takeoff roll and 1000+ fpm climb ...
I still fail to see under most circumstances why I would want to use flaps:confused:
 
MauiLvrs said:
And with a 9 that has a 300-400 foot takeoff roll and 1000+ fpm climb ...
I still fail to see under most circumstances why I would want to use flaps:confused:
Click to expand...

... The why question has been answered as to several advantages. Perhaps a more appropriate question would be, "Why Not"? ..Allan...:confused:
 
I never intentional used flaps for take off. However, I have to confess that one time during early days I forgot to retract flaps before taking off. After making departure turn I was puzzled why I was not gaining airspeed. It took me a few seconds to realize that flaps were still down. Flaps did not fell off and after another 1,000+ hrs they are still working.
 
Forgetful

I live on a 2600 ft. Grass Strip and should use flaps, but don't because seems like everytime I do I forget to take them off, call it a Senior Moment. I like the fact that some of you ALWAYS use flaps no matter which kind of runway and it becomes second nature thing to do. I will start ALWAYS using them. Would like to see a poll on this subject.....
 
Do you have a TW or NW?

I think another relevant question would be if the plane has a tail wheel, or a nose wheel...
 
thanks for the discussion points...

i am going to start using them in my -9 and grass strip and see if i like them. logic tells me they'll help get the tail up - and then the whole airplane up - sooner, plus there are those other advantages others mentioned already, so why not? in fact, i kind of wonder why it took this discussion for me to try it.
 
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