[YEAGER007]

Awesome aircraft! Thank you!

I'd really love to see more of these secret Japanese aircraft.

All that is needed now are some high-res cockpit textures to match the rest of this very nice model!

B.T.W. Is there any way to keep the aircraft from bouncing up and down while taxing on the ground?

Keep up the good work! 8)

[shyrsio]

I think the bouncing is quite historical, maybe due to his "long legs" check this:
http://www.youtube.com/watch?v=LW_8gi10spM

Kodama, is there any chance to fix the torque direction for the final FM? i think it shouldn't spin the same direction as the propeller but the other way around.

[YEAGER007]

I see… Maybe the frequency of the suspension bouncing just needs to be a little bit slower then ... more like a slow wallow.

I also read that the small wheels on the fins actually retracted in flight with the other wheels.

I feel the current seating position (POV) is perfect. Any lower would seem unrealistic to me. It will also make it very difficult to lead your shots if it was any lower.
Maybe keep a version for us that don't want to use the 6dof mod, which uses the current seating height.

As far as the future flight model goes... Canard aircraft normally display very safe stall characteristics...
In fact, a canard aircraft can be made to be virtually stall-proof, because the front canard will tend to stall before the main wing.
This means a canard aircraft naturally keeps the main wing's angle of attack within safe limits. The nose will naturally drop, but control will still be there...
In theory this will also REDUCE the tendency of the aircraft to spin.

Canards do however require slightly longer take-off and landing distances. Approach and takeoff speeds are also usually higher in canard equipped aircraft.
During approach a canard usually displays a slightly nose down attitude when using flaps. This will also eliminate the need for a lot of flare on touchdown.

The canard also reduces air resistance because it creates positive lift unlike a conventional tailplane that produces downforce to pitch the nose up. This will in part explain the J7W1's 750km/h top speed, but of course the 2130 hp engine also helps.

Torque in CRUISE will be compensated for by the manufacturer through the use of tabs on the control surfaces to reduce any roll tendency in normal cruise.

[caldrail]

The canard also reduces air resistance because it creates positive lift unlike a conventional tailplane that produces downforce to pitch the nose up.

Conventional tailpanes don't work like that. Quite the reverse, they add a small measure of lift to keep the tail from dropping. But the main benefit is a 'steadying' effect, which is the entire point of adding one to your aeroplane.

[kodama]

I think the bouncing is quite historical, maybe due to his "long legs" check this:
http://www.youtube.com/watch?v=LW_8gi10spM

Kodama, is there any chance to fix the torque direction for the final FM? i think it shouldn't spin the same direction as the propeller but the other way around.

Of course, j7 will get correct flight model in future.
And please keep this in mind, I use p-63's FM in this version.
The bouncing is also caused by p-63's FM.

[YEAGER007]

Thank you, mr Kodama.

I'm just trying to give some positive input because I feel so enthusiastic about this project of yours! :)

The project is already looking awesome and I can see you have a very good eye for detail!

Keep up the good work! 8)

[Guest]

I think the bouncing is quite historical, maybe due to his "long legs" check this:
http://www.youtube.com/watch?v=LW_8gi10spM

Kodama, is there any chance to fix the torque direction for the final FM? i think it shouldn't spin the same direction as the propeller but the other way around.

Of course, j7 will get correct flight model in future.
And please keep this in mind, I use p-63's FM in this version.
The bouncing is also caused by p-63's FM.

Guys at SAS gave it a realistic FM.

[YEAGER007]

The canard also reduces air resistance because it creates positive lift unlike a conventional tailplane that produces downforce to pitch the nose up.

Conventional tailpanes don't work like that. Quite the reverse, they add a small measure of lift to keep the tail from dropping. But the main benefit is a 'steadying' effect, which is the entire point of adding one to your aeroplane.

As a matter of fact it works exactly like that when you pull back on the stick. We're talking about the tailplane in relation to the rest of the aircraft, not the ground. I’m obviously not suggesting that it constantly produces negative lift. Why would you think that?

A tailplane and its control surfaces are more than just a mere measure of stabilization; it is an airfoil that is capable of attaining both positive and negative lift thanks to the elevator. A rear horizontal tailplane is also not an absolute necessity for stability... There are many aircraft without rear horizontal tailplanes and many of them are very high performance aircraft.

The tail of an aircraft will also not just “drop” like a brick without a rear tailplane, because an aircraft is always balanced around the spar of its main wing. Aircraft are never designed to be “tail-heavy”. The tailplane is in actual fact not supposed to support the weight of the aircraft like the main wing. Its function is to provide control over the aircraft, not to keep the tail in the air. In fact, during cruise a tailplane shouldn’t provide lift, it should be as neutral as possible. This causes the least amount of induced drag.

When you pull back on the yoke the elevator is deflected up, causing the tailplane to act like an inverted wing, just like the wing on a F1 car is an inverted wing. There is no difference in basic concept between an elevator deflected upwards when you pull back on the yoke, and an F1 car’s rear wing. If you’re not convinced, just look at them in profile and notice the resemblance in the basic concept. Of course, unlike the car’s wing a tailplane is capable of both positive and negative lift.

When you pull back on the yoke, the elevator deflects up, creating negative lift on the tail. This negative lift does in fact, despite what you might believe, cause the tail to lower in relation the main wing (CoG). This puts the aircraft in a nose-up attitude, which increases the angle of attack on the main wing, resulting in an increase of lift on the main wing. When climbing, the negative lift created by the tailplane in relation to the main wing cancels out a certain percentage of the main wing's lift, increasing the total amount of induced drag and making the combination less efficient.

When you push the yoke down, the elevator deflects down, creating positive lift at the tail and raising the tail in relation to the main wings. This puts the nose in a downward attitude, decreasing the angle of attack on the main wings and reducing lift on the main wings. Again the tailplane works against the main wing, which decreases the combination’s aerodynamic efficiency.

Notice how maneuverable unlimited aerobatic aircraft are… When they pull up hard there is a HUGE amount of negative lift pulling the tail down in the opposite direction of the main wing’s lift, otherwise they would never be able to do the aerobatic maneuvers they are capable of.

In a canard design the canard produces positive lift during a climb in order to raise the nose, which added with the main wing's increased lift (due to the increased angle of attack) makes it more aerodynamically efficient.

Common sense, really. And one doesn’t need to be an aeronautical engineer to understand the concept either. 8)

[Guest]

Just like forward swept wings do the opposite to normal swept wings.

[caldrail]

The canard also reduces air resistance because it creates positive lift unlike a conventional tailplane that produces downforce to pitch the nose up.

Conventional tailpanes don't work like that. Quite the reverse, they add a small measure of lift to keep the tail from dropping. But the main benefit is a 'steadying' effect, which is the entire point of adding one to your aeroplane.

As a matter of fact it works exactly like that when you pull back on the stick. We're talking about the tailplane in relation to the rest of the aircraft, not the ground. I’m obviously not suggesting that it constantly produces negative lift. Why would you think that?

A tailplane and its control surfaces are more than just a mere measure of stabilization; it is an airfoil that is capable of attaining both positive and negative lift thanks to the elevator. A rear horizontal tailplane is also not an absolute necessity for stability... There are many aircraft without rear horizontal tailplanes and many of them are very high performance aircraft.

The tail of an aircraft will also not just “drop” like a brick without a rear tailplane, because an aircraft is always balanced around the spar of its main wing. Aircraft are never designed to be “tail-heavy”. The tailplane is in actual fact not supposed to support the weight of the aircraft like the main wing. Its function is to provide control over the aircraft, not to keep the tail in the air. In fact, during cruise a tailplane shouldn’t provide lift, it should be as neutral as possible. This causes the least amount of induced drag.

When you pull back on the yoke the elevator is deflected up, causing the tailplane to act like an inverted wing, just like the wing on a F1 car is an inverted wing. There is no difference in basic concept between an elevator deflected upwards when you pull back on the yoke, and an F1 car’s rear wing. If you’re not convinced, just look at them in profile and notice the resemblance in the basic concept. Of course, unlike the car’s wing a tailplane is capable of both positive and negative lift.

When you pull back on the yoke, the elevator deflects up, creating negative lift on the tail. This negative lift does in fact, despite what you might believe, cause the tail to lower in relation the main wing (CoG). This puts the aircraft in a nose-up attitude, which increases the angle of attack on the main wing, resulting in an increase of lift on the main wing. When climbing, the negative lift created by the tailplane in relation to the main wing cancels out a certain percentage of the main wing's lift, increasing the total amount of induced drag and making the combination less efficient.

When you push the yoke down, the elevator deflects down, creating positive lift at the tail and raising the tail in relation to the main wings. This puts the nose in a downward attitude, decreasing the angle of attack on the main wings and reducing lift on the main wings. Again the tailplane works against the main wing, which decreases the combination’s aerodynamic efficiency.

Notice how maneuverable unlimited aerobatic aircraft are… When they pull up hard there is a HUGE amount of negative lift pulling the tail down in the opposite direction of the main wing’s lift, otherwise they would never be able to do the aerobatic maneuvers they are capable of.

Oh dear. if your theory was right, the aeroplane would lose stability instantly and enter uncontrollable gyrations. It isn't about positive or negative lift - it's the airflow deflection that enables fore and aft control. Aircraft do indeed balance, but on the centre of gravity, not the wing spar, and without airflow past the rear surfaces, there would be nothing to support the weight of the rear fuselage, though strictly speaking it would depend on the design whether the aeroplane flipped forward or back. You're right, you don't need to be an aeronautical engineer, but the science is often misapplied. As it happens, I'm a lapsed pilot in real life and I do therefore have some experience in the matter, aerobatics as well.

[YEAGER007]

Oh dear. if your theory was right, the aeroplane would lose stability instantly and enter uncontrollable gyrations. It isn't about positive or negative lift - it's the airflow deflection that enables fore and aft control. Aircraft do indeed balance, but on the centre of gravity, not the wing spar, and without airflow past the rear surfaces, there would be nothing to support the weight of the rear fuselage, though strictly speaking it would depend on the design whether the aeroplane flipped forward or back. You're right, you don't need to be an aeronautical engineer, but the science is often misapplied. As it happens, I'm a lapsed pilot in real life and I do therefore have some experience in the matter, aerobatics as well.

LOL, I give up. I guess according to you the Shinden should lose stability instantly and enter uncontrollable gyrations. So should a Mirage III, Atlas Cheetah, Concorde, Tu144, Me163, B2, etc... :lol:
Sure, a conventional aircraft needs a tailplane because it was DESIGNED to use one. But you don’t need to design an aircraft with a rear horizontal tailplane at all. There are MANY aircraft without any rear horizontal tailplane and they don’t lose stability instantly as you claim.

Not about positive or negative lift you say? You may want to see it as merely wind being deflected, but that is a real kindergarten type of way to explain an airfoil, since a brick also deflects wind.

Here you go on about the rear of the aircraft's weight being supported by the tailplane again. Get this - The tail's weight is carried by the main wing, just as the nose and the rest of the entire aircraft's weight is carried by the main wing in a conventional aircraft.

You don't even know that in most aircraft the center of gravity is over the main wing spar. It is the strongest part of the wing, so it needs to carry the most weight of the aircraft and the aircraft's weight needs to be centered around it. The whole aircraft needs to be balanced around its wings.

Ps. You're not the only pilot in real life (I've been both a fixed and rotary wing pilot for over 14 years), so you don't impress me with being a LAPSED pilot. It 's actually a shame that even the most basics of the theory still elude you.

[caldrail]

Being a lapsed pilot is merely a matter of circumstance. Flying is expensive in Britain and like a great many other pilots flying on a budget I've had no choice but to give it up. Your attitude is a little disrespectful.

But - Regarding the matter of tailplane aerodynamics. I am quite amused by your assertion that my viewpoint is one of kindergarten level, since you clearly haven't looked closely at the issue. Let's look closer then.

What is "lift"? Basically it's the result of of an imbalance of air pressure on both sides of a surface moving through the air. That much is readily understood (the 'kindergarten' level). However, we need to realise that lift is a compound force. It arises from more than one effect.

The first effect is the result of air striking a surface. It stands to reason that air pressure will increase if a surface obstructs the airflow, even at a shallow angle, which we call Angle of Attack. Unfortunately, because the surface is obstructing the airflow, we also generate drag. According to conventional wisdom on aerodynamics, this effect provides around one third of the total lift generated, but notice that can only be true if the surface has an angle of attack. In a perfect minimum drag condition, there should ideally be zero lift from this source.

The second effect is one derived from the shape of the airflow. Because airflow across a surface reduces air pressure upon it, by making one side bulge slightly the air has further to travel and therefore must travel faster across it to meet at the trailing edge. We therefore get a region of reduced air pressure above the surface of a conventional wing. Approximately two thirds of lift from a wing can be generated from this source.

Lift is then a compound of higher pressure below, and reduced pressure above. The amount of lift varies according to various circumstances, such as forward velocity and angle of attack. The total is one thing. The value of lift from it's component sources varies according to conditions too.

That describes our main lifting surface, the wing. The tailplane is not there to lift the aeroplane (although I concede some designs, especially primitive edwardian aircraft, were effectively tandem winged aeroplanes) but to provide stability in the same way as the feathers of an arrow. In a perfect minimum drag condition, the tailplane should not need to generate any aerodynamic forces at all, though for practical reasons a very small amount is necessary to 'balance' the aeroplane in flight - the weight of the rear fuselage is always present.

If the angle of the fuselage diverges from that of foward travel, the tailplane presents a surface that the airflow will impact upon. There is no lift generated from the airfoil section - the taiklplane is ideally an aerodynamically neutral surface - but merely that caused by airflow impacting on the surface, and that condition is hopefully temporary because the effect is to return the fuselage to it's former attitude. It's a stability function, and the entire reason for the tailplane being there. In practice, there will likely be a very small component of this force generated all the time as the aeroplane is dragging its rear structure through the air against gravity. As already mentioned, this generates drag, and thus is an undesirable characteristic for performance reasons.

If we decide to impart a change of attitude from the controls, we move the elevator (or indeed, the entire tailplane on some aircraft) at an angle to the airflow. The air is deflected and the attitude of the aerplane changes, modified by forward velocity into a controllable manoever since the stabilising effect of the tailplane is still present. Slab tailplanes do not generate any appreciable lift from their airfoil section. How can they? The shape is neutral. But if fitted with elevators, does the modifying of the cross section by movement of the cobntrol surface actually form an airfoil that generates lift? Your proposition is based on that assumption. That is the cause of the misunderstanding.

The deflected elevator does not change the length of travel for airflow. By definition, it cannot generate reduced air pressure on the opposite surface. All we get is the first component of lift which is direct air pressure as the flow impacts against the obstructing control surface. The aeroplane responds by attempting to balance the forces generated by our control input, and so the manoever ensues.

What we have then is a force generated by increased pressure on a control surface. It is not 'lift' in either direction because it does not have all the component forces that define it.

That's my point of view. Take it or leave it.

Incidentially, there's no practical reason for requiring a wing to have its main spar on the center of gravity. Some aircraft have multiple wing spars. I'm pretty sure they don't have multiple centre of gravity's. The centre of gravity is a physical property - its where the total mass can be balanced - the structure does not need to conform to that.

If you wish to debate theoretical subjects on the forums then please show a little more courtesy, otherwise I'll have to consider your fourteen years as an active pilot in fixed and rotary wings as an extraordinary example of good fortune.

[YEAGER007]

Ok, I guess I might have come across as a bit harsh. But I must say that you have been making some obvious annotations simply for the sake of arguing.

Most light aircraft have one main spar (there are obviously smaller spars in the wing as well). When an aircraft has more than one "main spar" (if you still want to call it that), then it will obviously not have multiple centers of gravity; the center of gravity will be between them. I think it is pretty obvious and truly didn't think it even needed mentioning, but apparently you didn’t consider it to be obvious. When discussing these basic aerodynamic principles it is also absolutely absurd to hammer on about every little variation in design just in order to be argumentative. The center of gravity also shifts slightly as cargo and passengers are loaded on the aircraft, but let’s not fret about it shifting a few cm to this side or that side just for the sake of arguing. And let’s not get into every slight center of gravity variation for each aircraft on the planet, please.

The reason a tailplane is not curved at the top and flat underneath, is because the function of the tailplane and elevator combination is to create either positive or negative lift at the tail in order to control pitch. Bulging it at the top would produce constant positive lift at the tail, which will make constant up trimming necessary just to keep the nose level (getting worse as speed increases). It would also increase induced drag and make it difficult to pitch the nose up. There are exceptions to this - caused by certain aircraft designs, but let’s please not hammer on about that either.

Most of what you said previously I can agree with (pretty basic principles that didn’t need mentioning in the first place), but at least it supports what I've been saying all along. However, you still don't seem to understand that when the elevator is deflected it causes both the angle of attack and the camber of the combined tailplane and elevator surface to produce either a lift or down force, depending on the deflection of the elevator. When the elevators are lowered -> increasing the camber, it creates an upward force called lift at the tailplane. When the elevators are raised -> decreasing the camber, it produces a downward force (negative lift) at the tailplane.

How do you think flaps work? Notice how a wing with lowered flaps looks similar in profile to a tailplane with a lowered elevator. Flaps work on the same aerodynamic principle as lowered elevators... When the flaps are lowered they increase the camber of the wing, which increases lift (the same applies to the tailplane and lowered elevator combination). On the other hand, when the elevator is raised it acts similar to an inverted flap, causing negative lift at the tail. The same principle applies to all the control surfaces of an aircraft. If you don't agree with that then I don't see any further use in continuing this discussion. In fact, if you want to continue this discussion at all I suggest we do it through PM since I think we've gone off this threads intended topic enough as is.

Ps. Before you PM me, please read up a bit on how the elevator changes lift at the tailplane by altering its camber.

I thank you.

[Fireskull]

8)

Interesting.

[caldrail]

Ok, I guess I might have come across as a bit harsh. But I must say that you have been making some obvious annotations simply for the sake of arguing.

No, I've been making it clear that your explanation is poorly defined, and provided a better one. Positive and negative lift are only present if both components are present, otherwise all you have is a measure of positive and negative air air pressure, which is the actual case.

Most light aircraft have one main spar (there are obviously smaller spars in the wing as well). When an aircraft has more than one "main spar" (if you still want to call it that), then it will obviously not have multiple centers of gravity; the center of gravity will be between them.

No, that isn't obvious. It depends on the design. Furthermore, as you claim to be a practising pilot of some experience, you will know that the position of the centre of gravity is not fixed. It varies according to the load carried on any particular flight, and one of the essential responsibilities of an aircraftas captain (as defined by CAA regulations) is to ensure the CoG is within safe limits for that flight. It isn't physically possible to keep the main spar and the CoG in the same place.

I think it is pretty obvious and truly didn't think it even needed mentioning, but apparently you didn’t consider it to be obvious. When discussing these basic aerodynamic principles it is also absolutely absurd to hammer on about every little variation in design just in order to be argumentative. The center of gravity also shifts slightly as cargo and passengers are loaded on the aircraft, but let’s not fret about it shifting a few cm to this side or that side just for the sake of arguing. And let’s not get into every slight center of gravity variation for each aircraft on the planet, please.

You're damning yourself as a careless pilot and for that reason please stay the heck out of my airspce. You're a danger to yourself and everyone else.

The reason a tailplane is not curved at the top and flat underneath, is because the function of the tailplane and elevator combination is to create either positive or negative lift at the tail in order to control pitch.

No, the function of the tailplane is to maintain stability. The elevator is there to control pitch. It's no good trying to teach me to suck eggs.

However, you still don't seem to understand that when the elevator is deflected it causes both the angle of attack and the camber of the combined tailplane and elevator surface to produce either a lift or down force,

I understand it perfectly well. There is increased air pressure on the deflected side plus the vector effect. The idea that increased camber causes this positive and negative lift ignores the fact that such aerofoil sections are inefficient and derive most of their lifting effect from air impacting one side, not from the camber, which does not in itself functionally change the speed of airflow across it the convex surface and thus does not create reduced air pressure on that side, thus does not produce 'lift'.

How do you think flaps work?

Irrelevant to the point. Especially since the trim changes of lowering flaps are usually in opposition to the deflection of the surface.

Ps. Before you PM me, please read up a bit on how the elevator changes lift at the tailplane by altering its camber.

I have absolutely no intention of PM'ing you whatsoever. Further, I don't consider further reading is necessary - I was after all responsible for an aircraft design thirty years ago. Also I suggest you take a course of further education in physics, in which you'll discover that definitions of properties are very important and that the sloppy explanations you insist on are inaccurate.