Flaps and Lift argument

[Rifleman]

Right you are Hagar.....I'll call it a draw and let the dust settle as everyone else lets this soak in.......not everyone can understand the basic principles that birds use to fly..........Damn birds, don't even have an inkling of what scientific stuff they are dealing with.....they just fly !

[Iroquois]

I should add that anywhere from 15-20 degrees, flaps produce enough lift to counteract drag, causing the plane to rise up with less speed. Above 20 degrees, this counteracting effect is defeated. The flaps begin to function more like spoilers because they cause more drag than lift.

Sorry if this has already been said but I don't have the attention span to read all the posts. Anyway, It is commonly thought that a plane flys by producing higher pressure underneath the wing than on top. This is part of it but areodynamics works more on the basis of Newtons basic laws of motion. That being that every action has an equal and opposite reaction. This law is used to explane how wing shapes other than flat-bottom fly. Most airplanes, other than trainers use a semi-symetrical wing or a fully symetrical wing.

How flaps work is the air rushing past the underside of the wing is forced downward. This inturn, according to Newton's law, forces the entire wing upward. Once again, flaps are only useful at certain speeds before drag takes over. Once the certain speed is reached, flaps become useless except as spoilers.

[Rifleman]

Once again, flaps are only useful at certain speeds before drag takes over. Once the certain speed is reached, flaps become useless except as spoilers.

This is essentially correct, but flaps never spoil lift.....that occurs on the upper surface of the wing as the airflow becomes turbulent due to some intrusion into the airflow (spoilers) or the critical angle of attack being exceeded and flow separation occurs........this increase in high drag may overpower the ability of the wing to support its load, but the flaps are not "spoiling the lift".....the flaps, themself, are sort of "after the fact" of the wings ability to generate lift.......

[Hagar]

I should add that anywhere from 15-20 degrees, flaps produce enough lift to counteract drag, causing the plane to rise up with less speed. Above 20 degrees, this counteracting effect is defeated. The flaps begin to function more like spoilers because they cause more drag than lift.

According to the Cranfield College of Aeronautics who spend all their time studying this stuff it's more like 40 - 45 degrees. I'm not in a position to argue. http://www.rmcs.cranfield.ac.uk/aeroxtra/e348wingdespflap.htm

Once again, flaps are only useful at certain speeds before drag takes over. Once the certain speed is reached, flaps become useless except as spoilers.

As Rifleman points out, they would then be acting as airbrakes, not spoilers.

[packercolinl]

Now you've done it! I'm going to have to go and read all that stuff now

[Rifleman]

I should add that anywhere from 15-20 degrees, flaps produce enough lift to counteract drag, causing the plane to rise up with less speed.

Orenda,  not to be pickin, but lift and drag never counteract each other.......they are not opposing force on the basic chart.......they can have a combination effect, but never work in opposition........remember this chart ?...

The airplane in straight-and-level unaccelerated flight is acted on by four forces--lift, the upward acting force; weight, or gravity, the downward acting force; thrust, the forward acting force; and drag, the backward acting, or retarding force of wind resistance.


Lift opposes gravity.

Thrust opposes drag.

Drag and weight are forces inherent in anything lifted from the earth and moved through the air. Thrust and lift are artificially created forces used to overcome the forces of nature and enable an airplane to fly. The engine and propeller combination is designed to produce thrust to overcome drag. The wing is designed to produce lift to overcome the weight (or gravity).

In straight-and-level, unaccelerated flight, (Straight-and-level flight is coordinated flight at a constant altitude and heading) lift equals weight and thrust equals drag, though lift and weight will not equal thrust and drag. Any inequality between lift and weight will result in the airplane entering a climb or descent. Any inequality between thrust and drag while maintaining straight-and-level flight will result in acceleration or deceleration until the two forces become balanced.

[hikariken]

. The delta wing is particularly stable at low airspeeds & impossible to stall.
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I will just correct this point. A delta wing is the most intable type of wing at low speed!!!
If you need proof I wil tell you to look why the deltadaggers has been retired from the navy after only 7 month of operation. delta wing is the only one form of wing that permit mach1 and 2. so it is an obligation for concorde and now most of military aircraft. but those aircraft got high approch speed. the F4 phantomII was a very difficult plane at cat launch and for carrier approch. and today it is always difficult for delta wing pilot. at last concorde was the plan with the highert take off and landing speed

[Rifleman]

I'm not sure of what it is you are trying to say Hakariken, but it is possible to stall a delta............it only takes a much higher angle of attack in order to do so....power balance at low speeds is absolutely critical to prevent too much drag from overcoming airspeed and hence lift.........this is inherent in deltas, that they need a high angle of attack to enable the low speed regime of flight.......if has to do partly, with aspect ratio....a delta is usually very low, compared to a glider, which has a very high aspect ratio......(aspect ratio=wingspan to chord relationship)
As far as a delta being the only planform of wing to enable supersonic flight........look again.....from the very beginning, the Bell X-1 was a straight winged bird and it exceeded the sound barrier.........there have been many more since, which don't have a delta wing, although its much more preferable to utilize a swept wing over a straight wing......

[Craig.]

this could go on all night :)

[Hagar]

I will just correct this point. A delta wing is the most intable type of wing at low speed!!!
If you need proof I wil tell you to look why the deltadaggers has been retired from the navy after only 7 month of operation. delta wing is the only one form of wing that permit mach1 and 2. so it is an obligation for concorde and now most of military aircraft. but those aircraft got high approch speed. the F4 phantomII was a very difficult plane at cat launch and for carrier approch. and today it is always difficult for delta wing pilot. at last concorde was the plan with the highert take off and landing speed

I was referring to the classic delta wing used by the Vulcan & Concorde. The Vulcan was never supersonic. A true delta wing will not stall in the normal sense at low speed but mush without dropping a wing or losing a great deal of height. Having flown several delta-winged RC models I can confirm this. The F-4 Phantom II has separate horizontal tail surfaces & is not a conventional delta. I can't speak for the Delta Dagger as I have no knowledge of it or why it was unsuccessful.

[Iroquois]

[quote]
Orenda,

[Rifleman]

I can't speak for the Delta Dagger as I have no knowledge of it or why it was unsuccessful.

The Delta Dagger (F-102) was supposed to be a super-sonic interceptor, but was encumbered by high drag and not quite enough power (barely able to attain Mach 1) I was never aware of any (much less 7 months of operations) US Naval applications of this fighter.......when it was re-designed with the area rule of drag for fuselage cross section being applied, it came out as the F-106 Delta Dart and quickly became the formidable Mach 2 interceptor it was initally intended to be.......

[Rifleman]

[quote]

I worded it really badly. I ment gravity. I'm sure you guys aren't that stupid to not know what I ment.

[Lethal.Ambition]

WOW, you guys know so much

[Hagar]

Well AstroGeek, there's plenty here who know far more than me. I've been fascinated with flight since the age of 6 & been flying models of one type or another ever since. What with that & working in the aircraft industry for 40 years something is bound to stick. My memory is failing & I've forgotten more than I can remember now.

I should have learned by now to keep out of these technical discussions. When I see someone say something I know is wrong I just can't help myself.  ;)