bigbri

My Feedback: (287)

Ok when doing a nice slow flyby how much flaps do you guys use??? And why
Thanks
Brian

Jetkopter

My Feedback: (1)

Brian, if Dom is on your tail better forget about flaps and just go to full after burner. Its Funny you brought this up because Turocy just called me and asked how he can put 12 smoke nozzle on his motor. He also wanted to know if I had a sound bite of a crowd booing. oh well just ignore them. To answer your question if you want to go slow use full flaps and crow if you got it and carry some power in case the head wind dies. I just tested my new Tam smoke nozzle with the power box pump and its killer. Unless your going to build a bon fire and pour a gallon of smoke oil on it I don't think you got a chance this weekend.

wojtek

My Feedback: (73)

around 45 - 50 max on slow fly by ... less than that may actually give you more lift, but i like the braking drag flaps give you .. depends on the model. this requires doing the slow low pass with more throttle ... this is good as when you need to pull out, there is not as much worry as if when spooling from a lower RPM ... basically, "drag" the jet through the low slow pass ... don't dump the flaps till pulled well out, as pulling flaps back up at too low of a speed can cause either stall, loss of needed lift, or altitude ..

Also, be aware of the ground effect cushion . You can slow way down when really low, and you are flying on a ground effect cushion ... does not mean you can pull out of this without gaining a lot more speed however .


Voy

racer8297

My Feedback: (13)

Hey Brian,

Are you serious about that? You have a fever or something?

Seriously man, you gotta lay off the popcorn balls. I think they are going to your head!

Hi to you, Dom and Bob.

Jim
Farview RC Flyers

AndyAndrews

Full Flaps and speed brakes. This is because you need all of the additional lift you can get at the slow speeds.

Andy

AndyAndrews

less flaps DO NOT give you more lift. Flaps are a lift generating device. Not the opposite. The answer to the additional drag is more thrust.

wojtek

My Feedback: (73)

depends on the plane / wing ... On some airframes stall speed is significantly lower with flaps deployed . better lift at low speed. . ( not always the case when using FULL flaps ... ) its a balance between braking / lift ... take it a step further, and some aircraft have extending flaps ( like fowler ) this definitely gives more lift and actually increases surface area .

Voy

JackD

My Feedback: (4)

Andy, there is a curve. More flaps give you more lift to a point, then they produce less lift and more drag. Usually, the optimum is around TO flaps. THat is also why, when you have a deadstick, you go to TO flaps, to maximize your glide ratio

But at landing flaps, usually there is less lift. You want the induced drag, plus the flaps will make the center section of the wing stall first, keeping the wingtips flying and avoiding tip stalls.

The reason you want to go full flaps, full speedbrakes on a dirty flyby, is because you can get on the side of the curve where your airplane flies on the power (high alpha type of flying).

Erik R

My Feedback: (32)

Jack,

Respectfully,a clean wing flown at L/D max speed will always give you a better glide ratio than a wing with any amount of flap,or leading edge device deployed, at that respective L/D max speed.

Erik

AndyAndrews

[/quote]



But at landing flaps, usually there is less lift. You want the induced drag, plus the flaps will make the center section of the wing stall first, keeping the wingtips flying and avoiding tip stalls.

[/quote]

Right, that is why you want full flaps (per design of the particular wing type used) at slow speed dirty passes to prevent stalls. Obviously if you extend flaps past the point of this curve it's beyond the design parameters of that specific wing type. Why would anyone want to extend flaps beyond the design curve when the optimal point is at the center section (which is optimal lift at slow speed) you describe? When I said more flaps gives you more lift, what I meant is that full flaps correctly deployed at the levels designed for a the wing type give you the optimum amount of lift to prevent tip stalls. Not less flaps.

Andy

AndyAndrews

+1, I'm not going TO flaps on dead stick.. You are introducing more lift but there is always some extra drag coefficient upon deploying flaps and you don't want ANY more drag on a dead stick. You just want to make the runway at all costs.

AndyAndrews

Correct me if I am wrong but you just made the case for more flaps increasing lift not less. You want lower stall speeds with flaps deployed. Like you said Better lift at low speed, not less lift at slow speed which is exactly what we are talking about right? Plus the extra "braking/lift" you are talking about is compensated by extra thrust applied making the wing more stable (from tip stalls) at low speeds.

j.duncker

My Feedback: (2)

On an Avonds F 104 I found that using full flap as per the manual and slowing it down allowed a ferocious dutch roll to take place, however with 20 degrees of flap it could be flown at the same speed with no dutch roll.

Dustflyer

My Feedback: (13)

If you want to fly slow, you want maximum lift while generating minimum drag. That would be takeoff flaps. Take a look at an airliner the next time it takes off. You'll notice slats extended and a little bit of flaps. If the jet doesn't have slats, like a lot of corporate jets, RJ's, or -10 (little) DC-9's, you will see a little bit of of flap. A little flap gives lots more lift with very little additional drag. As you add flap, up to a point, you get more lift and also more drag, a desirable thing for landing. Beyond a certain point, you stop gaining additional lift and just add drag.

So to answer your question, you want takeoff flaps. I can't tell you what that is for your airplane. I would guess you are looking at 5-15 degrees of deflection, but that is just a guess.

bigbri

My Feedback: (287)

Great responses guys. Really interesting reading. Thank you! Keep it coming! Hey Don I only wish Dominic was behind me. The ******* is alway ahead of me.... Been trying to beat him for 25 years! Nope all I ever get to do is chase him lol.... But I still try. Hey Jim. I know slow flight for me is crazy! I must be on a popcorn ball high... Lol. Hope all is well out the in PA. Dom and I will be out to burn some Kero with you guys soon!

racer8297

My Feedback: (13)

Hey Brian,

The field is rolled and just waiting for you guys! 2 jet events this year, one in August and one in October! Can't wait!

Are you getting bored with your normal style of flying? You have always been a pleasure to watch!

Jim
Farview RC Flyers

Meesh

My Feedback: (135)

Hey Jim,

Brian is not ill. We are having a smoke out this weekend and he's trying to maximize the effect. I don't hink he can take another booing from the spectators.

We'll probably see you guys in October.

Take care
Bob

Jetkopter

My Feedback: (1)

Bob here is the poster child for stuck throttle 2013

Meesh

My Feedback: (135)

LMAO!

bigbri

My Feedback: (287)

I want to go slow to mess with Dominic's head!!!! He wont know what to make of it!.... Lol... Just let "Hollywood" Turocey know I am gunning for him this year at the smoke off! : ) I will not be boo'd this year!

Granpooba

My Feedback: (5)

Never got any lift from speed brakes ! But I am speaking real life and not models !

Definition of flaps are devices that give an increase angle of decent with no speed increase.

DWD " ATP "

AndyAndrews

The speed brakes aren't for lift. They are to create drag which helps the jet slow down..

Definition of flaps from Websters Dictionary:

"a hinged or pivoted and sometimes extensible portion of an airplane wing used to increase the lift and drag for making landings at reduced speeds"

Doug Cronkhite

My Feedback: (34)

I'll trust aerodynamics over Webster's to be correct here.

Flaps are devices designed to increase the angle of descent without increasing airspeed. At lower deflection levels they increase lift over a 'clean' wing, but at some point, you end up in a trade-off between lift and drag where lift stops increasing, while drag rises sharply. Some (most) of our models have enough thrust to overcome this drag rise, but for a really good slow flight regime, I've always found takeoff flaps to be optimal. If you have speed brakes too, that's all the better, because they'll allow you to run higher thrust levels, which gives you instant energy increase if you need to go around or climb out simply by closing them. No spool-up time or waiting for thrust.

AndyAndrews

All I know is that I can make my BVM F-86 come to a virtual crawl with full flaps and air brakes and gear down with straight and level flight. Maybe it would do better with TO flaps. I'll try it and see.

Dustflyer

My Feedback: (13)

All I know is that I can make my BVM F-86 come to a virtual crawl with full flaps and air brakes and gear down with straight and level flight. Maybe it would do better with TO flaps. I'll try it and see.
[/quote]

Full flaps may be giving you approximately the same lift as takeoff flaps only with more drag. Speed brakes and gear down add to the drag. The net result is you can fly slow but it requires a lot of thrust. Takeoff flaps clean would likely do the same thing only with a lot less power. What I would love to know is how much less. It may actually feel more comfortable to fly slow with everything hanging and the power pushed up. A slow flyby with takeoff flaps only might only take a little more than idle thrust. Since we fly these little buggers with sight and sound, it might look and feel a lot less solid with the airplane just whistling by. Then again, I've seen Dave Malchione do slow flybys with his KingCat that were spectacular. As I recall the gear was up and just a little flap hanging. It was going so slow you felt you could reach out and grab it, if you weren't looking at the flight line you'd never know it flew by. I know because he's snuck it past me many a time!