[drmax]

Hello. My runway has a slight raise in it at about 900 ft. I lift off, solo at 60, come off the ground a bit, then settle back down a bit due to the hump, which is a little "unsettling". This is with 10 degrees. Going the other way is about 1200 feet before the raise, and is non issue. I don't want this to happen on a windy crosswind day, especially with passenger. I have not experimented with 20 degrees flaps as of yet. I'm 160 lyc fixed pitch metal.
Surfaceasphaltt. Your advice please. DM

 

[jmbrwn]

I would suggest trying 15 degrees of flaps first and see how that works. I use this off our 2400' grass strip with a 150hp Lyc fixed pitch, and seems to work well. I have no data to back it up, but 20 degrees seems like more drag than lift...my opinion only.

 

[blueflyer]

maybe try short field t/o procedure to get airborne before the "bump" in the runway.

 

[N941WR]

Two options, the first is don't climb after you lift off. Fly it in ground effect, and inch off the ground, until 65, then rotate and accelerate to your desired climb speed. That won't take very long or take up more room.

As for the flap setting, I lower the aileron and drop to flaps to match them. That gives you 15* +/- which works out to about 1/2 flaps in the -9.

 

[turbo]

try lifting off at 65. this may give you more ummph so you dont settle back down. follow the hump in ground effect.

 

[Mel]

As has been stated above, 15° is optimum for max lift and min drag. I've done experiments with all flap settings and 15° works out best.

The aileron "down" travel is set to 15° for this reason. It also makes it convenient to set the flaps if you have electric. Just align the flaps with the "down" aileron and you're set to go.

I actually use 13°, but that's because my manual flaps have 13, 26, and 39° notches.

 

[Sam Buchanan]

As has been stated above, 15? is optimum for max lift and min drag. I've done experiments with all flap settings and 15? works out best.

The aileron "down" travel is set to 15? for this reason. It also makes it convenient to set the flaps if you have electric. Just align the flaps with the "down" aileron and you're set to go.

I actually use 13?, but that's because my manual flaps have 13, 26, and 39? notches.

This is the proper way to set your flaps, it will help you pop off the ground a little quicker. But be advised it will also retard acceleration once you leave the ground. As soon as you are a few feet above the ground begin retracting the flaps so the plane can accelerate promptly.

 

[N941WR]

This is the proper way to set your flaps, it will help you pop off the ground a little quicker. But be advised it will also retard acceleration once you leave the ground. As soon as you are a few feet above the ground begin retracting the flaps so the plane can accelerate promptly.

I disagree with this.

Don't be in a hurry to retract the flaps. Let the plane accelerate with the flaps down so you don't settle back on the ground. Once you have established a positive climb rate, well above the flaps up stall speed, then the flaps should be retracted and either Vx or Vy established, depending on the conditions/needs.

 

[Sam Buchanan]

This is the proper way to set your flaps, it will help you pop off the ground a little quicker. But be advised it will also retard acceleration once you leave the ground. As soon as you are a few feet above the ground begin retracting the flaps so the plane can accelerate promptly.

I disagree with this.

Don't be in a hurry to retract the flaps. Let the plane accelerate with the flaps down so you don't settle back on the ground. Once you have established a positive climb rate, well above the flaps up stall speed, then the flaps should be retracted and either Vx or Vy established, depending on the conditions/needs.

Bill, I don't think we disagree.

My RV-6 (and I suspect most RV's) will establish a positive climb rate above stall speed a few feet above the ground.

 

[N941WR]

Bill, I don't think we disagree.

My RV-6 (and I suspect most RV's) will establish a positive climb rate above stall speed a few feet above the ground.

Yep, I agree. Even when I had the small (135 hp) engine in my -9, it would jump off the ground and rotate to a positve rate of climb very quickly. With the 180+ HP engine, it just does it faster.

 

[Ironflight]

Unless I am operating from a VERY short or soft field, where it is a real question if I will get out or not (and for an RV, that is way less than 1,00'), I just leave the flaps up. I know this is counter to a lot of folks thoughts, but the RV performance is so good, and you'll be off the ground so quickly, that the task of messing with the flaps close to the ground - while not accelerating above the VERY LOW "flap deployed" speed is, for me a distraction I don't want. Sure, there are special cases where i might do it - but these aren't Boeings whose wings unfold to generate enough lift to fly.

I don't really have a problem that many folks use flaps for take-off...I just don't like to be having to mess with stuff at that point when I can simply just fly the airplane. On normal runways, the extra half-second I get off earlier with the flaps doesn't mean that much.

 

[drmax]

my elect. flaps

The builder told be they are set for 10, 20 and 30 degrees, holding the switch 1 second to get each notch. I'll hold her down a bit longer, but like trying to hold down a bull fixing to get branded! I will NOT use 20, so you folks need not worry. Thx for being with me on this. DM

 

[Sam Buchanan]

Unless I am operating from a VERY short or soft field, where it is a real question if I will get out or not (and for an RV, that is way less than 1,00'), I just leave the flaps up. I know this is counter to a lot of folks thoughts, but the RV performance is so good, and you'll be off the ground so quickly, that the task of messing with the flaps close to the ground - while not accelerating above the VERY LOW "flap deployed" speed is, for me a distraction I don't want. Sure, there are special cases where i might do it - but these aren't Boeings whose wings unfold to generate enough lift to fly.

I don't really have a problem that many folks use flaps for take-off...I just don't like to be having to mess with stuff at that point when I can simply just fly the airplane. On normal runways, the extra half-second I get off earlier with the flaps doesn't mean that much.

Agreed. The original post was asking how to achieve a maximum performance takeoff and that is how the thread got off on using flaps.

There are only two short grass strips in my area where I use flaps for takeoff and then only if hot and/or heavy. Any other time is just isn't worth the effort.

 

[Wayne Gillispie]

Ditto...

Two options, the first is don't climb after you lift off. Fly it in ground effect, and inch off the ground, until 65, then rotate and accelerate to your desired climb speed. That won't take very long or take up more room.

As for the flap setting, I lower the aileron and drop to flaps to match them. That gives you 15* +/- which works out to about 1/2 flaps in the -9.

I would get a good Vx climb going until 100' or more AGL, then retract flaps incrementally. If you get close to flap limiting speeds, pull the nose up more.

In my -10 at gross on 2100' asphalt(Cedar Key) no flaps needed as I am off by 1000'-1500' depending on temps. In his -9 at gross, fixed pitch, 160 hp...I'd use flaps. We CS prop drivers sometimes think all RV's accelerate like ours and they just won't do it.

 

[170 driver]

My RV 9 gets off well before 900 ft,,,it's a 150 hp FP,,,Vans specs say 300 ft with 160 hp...I can't imagine being close to the ground at 900 ft with any flap setting. I rarely use flaps for takeoff at all.

 

[JDRhodes]

Unless I am operating from a VERY short or soft field, where it is a real question if I will get out or not (and for an RV, that is way less than 1,00'), I just leave the flaps up. I know this is counter to a lot of folks thoughts, but the RV performance is so good, and you'll be off the ground so quickly, that the task of messing with the flaps close to the ground - while not accelerating above the VERY LOW "flap deployed" speed is, for me a distraction I don't want. Sure, there are special cases where i might do it - but these aren't Boeings whose wings unfold to generate enough lift to fly.

I don't really have a problem that many folks use flaps for take-off...I just don't like to be having to mess with stuff at that point when I can simply just fly the airplane. On normal runways, the extra half-second I get off earlier with the flaps doesn't mean that much.

I've always used take off flaps in the RV-9, but don't in the -7. The progressive fowler-style flaps on the -9 seem to provide a little more benefit than the flat planks on the less sofisticated RV's

Regardless of length, I like the idea of getting the airplane off the relatively rough grass as soon as possible. I'd rather be flying, and accelerating, in ground effect than rolling another 50 feet in the grass.

I'll clean up at 100+ feet with a good climb rate established. Just watch the flap speeds at < 90 mph

 

[Jeff R]

Given a -xA, I would be hesitant to hold the nose down at all on takeoff. You don't want to be flipping over at full power! I always pull the stick back on takeoff, and am off within 400 feet, if that, with an IO-320.

 

[Mel]

As my first instructor always told me.....

Given a -xA, I would be hesitant to hold the nose down at all on takeoff. You don't want to be flipping over at full power! I always pull the stick back on takeoff, and am off within 400 feet, if that, with an IO-320.

"That nose wheel is for taxiing only, not for take-off or landing!"

 

[drmax]

My RV 9 gets off well before 900 ft,,,it's a 150 hp FP,,,Vans specs say 300 ft with 160 hp...I can't imagine being close to the ground at 900 ft with any flap setting. I rarely use flaps for takeoff at all.

what is your MPH at lift off, then? Also, your prop type? I don't understand why I'm not getting your results, if you have a metal prop like mine. I'm in Indiana and low densisty altitude, as of late. Thx, DM

 

[N941WR]

Given a -xA, I would be hesitant to hold the nose down at all on takeoff. You don't want to be flipping over at full power! I always pull the stick back on takeoff, and am off within 400 feet, if that, with an IO-320.

These suggestions for a -9(A). What works best in a short wing RV or an RV-10 or 12 might be different.
The proper soft field technique is to have 10 to 15 deployed, hold the stick all the way back, do not stop at the end of the runway. Remember, this is a soft field and you could sink in. As the plane starts to accelerate, give it some forward stick to keep the nose just an inch off the ground. This means you have to give it progressively more forward stick as you accelerate. When the plane lifts off, lower the nose some more to fly in ground effect as the plane gains more speed. Even with a FP prop, the plane will push you in the back of the seat once you are off the ground. After say 65 kts/ 70 MPH start your climb and establish your Vx or Vy speeds, depending on any obstructions on the field, as you retract the flaps.
If your nose is too high, you will make a longer than necessary takeoff roll. Too low and your front wheel will still be in the weeds.

BTW, the few times I have flow an ?A? model, I use the same technique even if on pavement.

Landings are another thing. Full flaps 65 to 70 MPH, depending on my load. Just before touchdown, I add very small amount of power to arrest the sink rate and just kiss the mains on. As soon as the mains are on, I pull the power off while working the stick aft. I let the nose drop on its own, again while holding the stick aft. The stick remains aft until shutdown.

 

[drmax]

These suggestions for a -9(A). What works best in a short wing RV or an RV-10 or 12 might be different.
The proper soft field technique is to have 10 to 15 deployed, hold the stick all the way back, do not stop at the end of the runway. Remember, this is a soft field and you could sink in. As the plane starts to accelerate, give it some forward stick to keep the nose just an inch off the ground. This means you have to give it progressively more forward stick as you accelerate. When the plane lifts off, lower the nose some more to fly in ground effect as the plane gains more speed. Even with a FP prop, the plane will push you in the back of the seat once you are off the ground. After say 65 kts/ 70 MPH start your climb and establish your Vx or Vy speeds, depending on any obstructions on the field, as you retract the flaps.
If your nose is too high, you will make a longer than necessary takeoff roll. Too low and your front wheel will still be in the weeds.

BTW, the few times I have flow an ?A? model, I use the same technique even if on pavement.

Landings are another thing. Full flaps 65 to 70 MPH, depending on my load. Just before touchdown, I add very small amount of power to arrest the sink rate and just kiss the mains on. As soon as the mains are on, I pull the power off while working the stick aft. I let the nose drop on its own, again while holding the stick aft. The stick remains aft until shutdown.

I believe it's simply my inexperience. I'll work on my technique a bit, uh and a longer runway. Thank you folks. Oh, and yes to the who said, "not keep it on the ground after 60 ish". That doesn't feel quite right. She wants to fly. I just am not gonna see 300 feet off the ground. Seems a bit unreal.

 

[170 driver]

I have a Catto prop,,,turns about 2150 or so on takeoff,,,here is the first takeoff video and I accelerated slowly,,,not a short field takeoff.

http://www.youtube.com/watch?v=GTseLYrE4aQ

 

[drmax]

I have a Catto prop,,,turns about 2150 or so on takeoff,,,here is the first takeoff video and I accelerated slowly,,,not a short field takeoff.

http://www.youtube.com/watch?v=GTseLYrE4aQ

COOL....where's the vid on the landing....
Uh, perhaps the catco is getting it for you. Maybe being a tail dragger?
Dunno. Guess I'll have a look at my rpm's saturday, before flight.

 

[170 driver]

Don't know ,,,but it gets off quick. No landing video's and probably a good thing,,,took me a good many flights to figure out how to land it without bouncing it.,,,the 180 hp RV4 chase plane fouled a plug and had to go back,I guess he was holding it back too much to not overtake me so video is short. My empty weight is 1050 and it was 3/4 full of fuel both tanks that day, after lift off the rpms come up different amounts depending on the climb angle and speed,,,and in level flight it will turn 2750 flat out at altitude with the wheel pants on, speeds are right about Van's posted numbers.

 

[drmax]

Don't know ,,,but it gets off quick. No landing video's and probably a good thing,,,took me a good many flights to figure out how to land it without bouncing it.,,,the 180 hp RV4 chase plane fouled a plug and had to go back,I guess he was holding it back too much to not overtake me so video is short. My empty weight is 1050 and it was 3/4 full of fuel both tanks that day, after lift off the rpms come up different amounts depending on the climb angle and speed,,,and in level flight it will turn 2750 flat out at altitude with the wheel pants on, speeds are right about Van's posted numbers.

mine is 1158 empty. i imagine your cato is giving you the get up and go.
take care

 

[airguy]

You guys give me energy to keep pounding rivets - I rarely use 10 degrees on my 172, I can't even understand needing it on an RV with that high power-to-weight ratio!

 

[MauiLvrs]

... I can't even understand needing it on an RV with that high power-to-weight ratio!

You don't generally need it ... some people use them anyway...

 

[N941WR]

You guys give me energy to keep pounding rivets - I rarely use 10 degrees on my 172, I can't even understand needing it on an RV with that high power-to-weight ratio!

Remember, he is asking about flying off of a grass strip, not pavement.

 

[Sunriver Ken]

Horsepower and Long Wings....love it

During a recent X-country from central-Oregon to Phoenix I stopped for fuel at Ely, NV elevation about 6,000. Temps were in the mid-80F and density altitude (per Dynon) was about 9,500. After topping off, the line-guy asked what I was going to do until the temperatures cooled down. He said none of the C's and P's were taking off due to D.A. I told him I was taking off ASAP. He gave me the WTF look.

Anyway, takeoff was a bit longer than normal but still way less than 2,500 feet. You have to love the long wings on the 9 and the 180 HP with a constant speed. Uneventful climb to 13.5 (cool air) and nice flight into Phoenix/ Glendale.

Thanks Van

 

[Neal@F14]

I rarely use 10 degrees on my 172, I can't even understand needing it on an RV with that high power-to-weight ratio!

Normally solo you never need to... but in my O-320, fixed pitch with extreme cruise pitch wood prop RV-6, on a soft field with two aboard and enough fuel to be very near full gross on a hot afternoon, setting the flaps for takeoff makes all the difference in the world.

For anybody that's been to Cedar Mills (3T0) on Lake Texoma, taking off to the east... ya know that bump about 1/3 the way down the runway? It launched me into the air well before the plane was ready to fly and we came right back down onto the mains with a scary bounce but I was able to arrest the bouncing and wheel-land the thing long enough so I could finish my takeoff roll (as the lake and that tree at the end of the runway were coming up a little too quickly for comfort). Oh how I was wishing for a 360 engine or a CS prop that day.
The next time we were there under similar circumstances (hot day, two aboard, not as much fuel that time) I used 15 deg flaps and was off the ground smoothly into ground effect before reaching that bump in the runway.