Tails and foreplanes are airfoils and can generate lift as wings do.
They can generate lift.... but like the torque generated by the tail rotor on a helicopter they don't really effect lift because any lift force lifting one end forces down the other end of the aircraft... the lift force that far from the cg creates a rotational effect around the cg... that is its purpose... rather than a keeping the aircraft in the air lift effect you seem to think it does.
In a plane with AoA 2deg. with tails at neutral position re. the fuselage, both wings and tails are generating lift.
In a statically unstable plane the canards or tail surfaces will be generating up or downward force to keep the nose pointing the way it is pointing.
If the canards and tails are in neutral then any lift they do generate in level flight will be needed to keep the nose level.
The neutral position also minimises drag and RCS in that position.
In fact the lift generated by the tails is crucial to calculate turning rates because on modern planes they do not need to be deflected negatively for the plane to turn (pitch up the nose with a banking angle) since they are unstable, and they add a sizeable amount of the total lift.
The lift or downwards force the tail generates in its neutral position is determined by the instability of the aircraft and which direction the nose naturally wants to go.
An unstable design might be great for instantaneous turn rates but the effect that even in level flight the tail surface or canard is bobbing up and down with tiny corrections to keep the nose pointing forward.
The best description of a flight control system for an unstable aircraft is like sitting on the front of a car holding the steering wheels of a bicycle facing backwards... dozens of tiny corrections a second are needed to keep that bike rolling in a straight line backwards in front of the car.
Not a good example of drag or lift.
Not if it is produced at the CoG, if it is produced after or behind, it needs to be compensated or it will make the plane lose longitudinal control.
Are you saying a horizontal tail or a canard on their own being one side of the cg or the other cannot control the aircraft longitudinally...
The wing generates the lift at the cg or near it... it keeps the aircraft in the air. The Canard or the tail surface or both or TVC engine nozzles use an up or downwards directional force to keep the nose of the aircraft pointing where you want it to point... if you took away the canards and the tail surfaces and replaced them with the engine nozzles that move you can still control the aircraft longitudinally... the aircraft flys around its cg no matter where it has moved to, and its primary control surface... in this example the engine nozzles.
Lift or downwards force is for controlling where the nose points.... the same as with canards and tail surfaces...
If you deflect the engine nozzles downwards in an Su-35 on takeoff the downward thrust will lift the rear of the aircraft but if you don't have canards also lifting the nose then the aircraft would rotate around the cg and the nose would drop into the ground... but by your view the upward angling of the engine nozzles creates lift at the rear which is a good thing isn't it... extra lift at takeoff?
A Harrier has four engine nozzles either side of the cg so the rear downward nozzles don't raise the rear and push the nose down because there are two more nozzles in front of the cg also pushing up which balances the rotation of the rear engines so the rotation around the cg is balanced and cancelled out but the lift from all four nozzles lifts the aircraft into the air and when angled backwards impart forward speed so the wings do generate some lift to offload the engines from having to carry the entire weight of the aircraft.
See above, they are airfoils and they create drag and lift by the same mechanisms the wings do.
You can't call it lift... because it is used to create a downward force as much as it is used to create an upward force... whether you want the nose to point up or down the purpose of the canard or tail surface is to achieve that... they are tiny and create a tiny fraction of the force the wing does... certainly not enough to hold the aircraft in the air.
With traditional stable planes it is either canards or tail, and without them you simply crash.
TVC could maintain control if needed... and the Mirage 2000 is a good example of an aircraft with a wing and no canards or tail surfaces and no thrust vector control jet engine either...
Not really. If at a given point of the flight envelope with a certain AoA you have 100 points of lift produced by the wings and you use the canards to trim, which produce 20 points, you have 120 points of total lift available.
There is no way a canard would generate that much lift in comparison to the main wing... that is just silly.
The main wing holds the aircraft in the air... the canards and tail surfaces merely point the nose... or the arse.
Look at the ailerons on a wing... that is closer to the effect of canards in terms of directing airflow for manouvering...
Not really. If at a given point of the flight envelope with a certain AoA you have 100 points of lift produced by the wings and you use the canards to trim, which produce 20 points, you have 120 points of total lift available. If you instead use the tails to trim, creating 20 points of downforce, you have 80 points of total lift available.
No, because the tail surface does not generate the lift needed for flight... the tail generates the force needed to shift the angle of attack which increases the main wing angle which means the main wing now generates 500 lift because the 20 points of down force from the tail lifted the nose to a new more efficient angle.
An aircraft does not fly by adding the lift from the wings and lift from the control surface... the lift from the wings keeps the aircraft in the air... the force generated by the tail or canard or directed engine nozzle manouvers the aircraft and can be used to increase lift by increasing the angle of attack, but once the change as been made the control surface... canard or tail or nozzle should be able to return to neutral to maintain the new angle unless there is a problem like you are flying too slow to maintain that nose attitude so you need to continue to use your canard or tail or nozzle to maintain perhaps a nose up attitude...
The point is that the effect of teh canard or tail or nozzle on the main wing will have much more effect on the lift and drag caused by the main wing or lifting fuselage than the tiny lift and increased drag the tail or canard have created to use that turning force to change the wing angle. Moving the nozzles does not cause drag increases to the same degree.
Obviously you will need either to reduce altitude or to increase AoA or to increase speed, but you will not be able to sustain level flight in the same conditions as the plane with canards. I recommend you to look for this on the many good sites about aerodynamics that you can find on the web, since I don't seem to be able to convince you.
Perhaps you need to look at the B-2 and the Mirage 2000... neither of which have canards or horizontal tail surfaces or thrust vector control engines... they do have ailerons, which they use like tailerons obviously because they have no choice, but the B-2 is considered to be a pretty clean and efficient aerodynamic shape isn't it? How can that be true when all flight controls generate a downward draggy anti lift force using the airflow from the main wing and only source of lift?
It depends. Zero airspeed full AB at sea level is not the same as corner speed cruise throttle at high altitude. You would need to crunch some numbers there.
When crunching those numbers don't forget to allow for stall effects in hard turns.... TVC nozzles don't stall BTW but severely deflected tail and canard surfaces can, and also allow for the momentum arm from the nozzle to the cg will always be greater than the distance from the canards an the cg and the tail surfaces and the cg.
I am all for TVC, I am only saying on a plane that needs to pitch up the nose, it is better to generate lift in front of the CoG than downforce behind.
The canard is normally located in front of the wing which is the cg.... the tail surface is generally further back on the aircraft so the momentum arm will be longer... the engine nozzles will be even further back with the longest arm...
When raising the nose... why do you think pushing the back down is any different from lifting the front... the result is the same... wing gets new higher angle of attack and more lift so you climb faster, fuselage body lift directed down at a greater angle equals even more lift and jet engines conventional or TVC are now pointing down angling the aircraft also up into the air through the cg line of thrust.
Do you think aircraft with tails temporarily descend on takeoff because the negative lift from the tail reduces lift and the aircraft is pushed into the runway... while aircraft with canards are thrown upwards with the sudden lift bonus of a super lifting canard?
When you run do you lift your feet up in the air in a jumping motion to run, or do you hammer your feet down into the ground to push your body into the air?
BTW before you reply I would add that the information I have seen is that of the fastest olympic sprinters the fastest ones are the ones that slam their feet downwards into the ground the hardest... quite counter-intuitive in my opinion, but facts are facts.
Wings could also be kept low drag at neutral position, only the plane would not fly then
Do you think the razor thin wings of the MiG-31 are high drag high lift wings ideal for high speed flight?
Modern wings can have leading edge slats that bend down and trailing edge flaps that form a highly curved high lift wing for takeoff and landing, while flatten and retract to a thin low drag aerofoil for high speed flight at high altitude...
The wings will be optimised for the intended optimum flight speed of the aircraft.
There is no sense in putting MiG-31 wings on an An-2, just like wings of the aerofoil used on the An-2 would make no sense on the MiG-41.
control surfaces contribute to the total lift generation.
The ones on the wing do, and other high lift devices that could be present...
Of course deflections need to be much smaller than the values you were giving above, above 15 deg almost any airfoil is going to stall.
I hope not... landing flaps are generally 20-25 degrees on most aircraft.
Angles of movement for tail and canard surfaces are usually rather more than 15 degrees... they are not tank gun barrels.
Every loss of lift through the downforce needs to be compensated by higher AoA which creates more drag.
Are you suggesting a canard works by allowing an aircraft in stable level flight to climb by being deflected upwards to increase the total lift so the aircraft climbs?
I would suggest the canard is temporarily deflected upwards or downwards which causes the nose to start moving in that relevant direction... but if you keep the canard at that deflected angle the nose will just continue to move and you will end up doing loops.
In level flight to start to climb you deflect the canards for half a second to turn the nose up say 30 degrees, but you have to then return the canard to neutral or the nose will just keep turning up and you will end up doing a loop.
The half a second you deflect the canard to raise the nose for a 30 or 40 degree climb it does generate a net lifting force, but for half a second and then it is returned to normal and the increased angle of attack of the main wing to 30-40 degrees is what makes the aircraft climb and lose a little speed because increased lift comes with increased drag... a bit more throttle for more power to maintain speed and you start to climb.
With tail surfaces it is exactly the same except a half second push down at the rear of the aircraft to lift the nose 30-40 degrees and then back to neutral to stop raising the nose... half a second of down force at the rear of the aircraft and you think this is important?
I think you favour aerodynamics that is pro european and therefore fascinated by canards.
I don't hate canards, but as shown by the Su-57 there are better options...
It was designed for manoeuvrability.
Without surface controls you cannot trim the plane and react to changes in CoG /CoL, there is no way around it. Even a flying wing needs surfaces to substitute tails.
Ailerons on conventional wings can do the job if the TVC fails, but the TVC does the job much better than tailerons or canards... lighter weight less drag no RCS.
Real data actually shows that you can reduce drag and generate more lift by using the TVC for trimming purposes:
And it becomes more important for long range high speed cruising aircraft... the right trim is very important in terms of natural drag.
A bit like a smooth golf ball vs a dimpled ball.
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... I have been wrong about plenty of things in the past and I am discussing this not to be right but to compare my view with others to find the truth...
, but on the other hand there wouldn't be such concern with the LEVCON's.
