Delta wing and Canard vs 'Conventional'
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Delta wing and Canard vs 'Conventional'
I find it interesting that while all contemporary US fighters have stuck with
a conventional wing and horizontal stabilizer layout modern European aircraft have gone with the delta wing with canard.
Typhoon / Gripen / Rafale all use this layout and there seem to be great advantages in terms of maneuverability, weapons and fuel capacity.
Curious as to why there's such a philosophical difference in design, is it maneuver driven or is there any relationship to stealth requirements.
Is there something intrinsically 'unstealthy' about a canard / delta layout that US designers would steer away from , or is it a case of staying with what they are most comfortable ?
a conventional wing and horizontal stabilizer layout modern European aircraft have gone with the delta wing with canard.
Typhoon / Gripen / Rafale all use this layout and there seem to be great advantages in terms of maneuverability, weapons and fuel capacity.
Curious as to why there's such a philosophical difference in design, is it maneuver driven or is there any relationship to stealth requirements.
Is there something intrinsically 'unstealthy' about a canard / delta layout that US designers would steer away from , or is it a case of staying with what they are most comfortable ?
The canards are useful for improved manoeuvrability at high angles of attacks as they're not masked from clean airflow by the wing itself at such attitudes.
I don't see that a canard is necessarily unstealthy, it depends what you make it out of.
Delta wings were considered by some designers in the old days to be a bad idea. Maybe that opinion stuck amongst the American design community. There's pros and cons to any wing design, and there's no real killer reason to choose a delta or something else. But I guess if one chooses a delta wing, canards make a lot of sense too.
I don't see that a canard is necessarily unstealthy, it depends what you make it out of.
Delta wings were considered by some designers in the old days to be a bad idea. Maybe that opinion stuck amongst the American design community. There's pros and cons to any wing design, and there's no real killer reason to choose a delta or something else. But I guess if one chooses a delta wing, canards make a lot of sense too.
Last edited by msbbarratt; 4th Nov 2016 at 06:28.
I've always assumed that it is because the US has a half-generation or so lead in fly-by-wire, stability control and aerodynamics, which allows them to get the required performance without foreplanes (which are likely to add cost, complexity, weight, radar profile, and drag).
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Wasn't the Viggen an inherently stable aircraft despite its' early canard-style (albeit not all-moving) layout?
One of the criticisms levelled at earlier 'pure' delta aircraft (such as the Mirage III/5) was that they bled too much airspeed in tight turns. Not sure how well (if at all) this was overcome with the later Mirage 2000...
On the other hand, GD/LM claimed that the double-delta 'cranked arrow' layout of the research only F-16XL (or F-16E) made canards unnecessary. Always wondered about this claim!
I think the 'secret' to instability (and thus turning performance) is loading the c.g. as far aft as possible. The 'normal' F-16 is a good example of this in a conventional layout. Canards just provide an efficient way of controlling the pitch-up tendency.
One of the criticisms levelled at earlier 'pure' delta aircraft (such as the Mirage III/5) was that they bled too much airspeed in tight turns. Not sure how well (if at all) this was overcome with the later Mirage 2000...
On the other hand, GD/LM claimed that the double-delta 'cranked arrow' layout of the research only F-16XL (or F-16E) made canards unnecessary. Always wondered about this claim!
I think the 'secret' to instability (and thus turning performance) is loading the c.g. as far aft as possible. The 'normal' F-16 is a good example of this in a conventional layout. Canards just provide an efficient way of controlling the pitch-up tendency.
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I think a lot is to do with design fashions. Remember also the Russians used canard etc on the SU22 (IIRC) and Concordski etc. Swing wing was fashionable before that, AFVG, Fitter etc.
Before that tailless deltas, B58, FD2 etc.
So you might argue that the US are ahead of the game with stealth tail less coming in.
Before that tailless deltas, B58, FD2 etc.
So you might argue that the US are ahead of the game with stealth tail less coming in.
Pedant mode on: if moveable, they are foreplanes, not canards: pedant mode off: sorry peeps.
Edit: Ahh, see megan asked the same thing
Well, I can't answer for the makers or engineers, but I assure you that to the aircrew, they are foreplanes.
Incidentally, the canards on the Viggen are "flapped", for STOL performance. Watch one on YouTube.
Incidentally, the canards on the Viggen are "flapped", for STOL performance. Watch one on YouTube.
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Everything in Typhoon is 'modern' so all of the terms for the systems and components are 'modern' as well, just so you don't forget.
I have read some new (< 10 yrs old) publications that refer to these before-wing control surfaces as foreplanes, but I have read many other (more classical) aerodynamic reference documents that refer to them as canards. Some even refer to the wing-foreplane combination as a canard configuration... This appears to be a European creation - modern US reference literature has yet to catch up.
It's a bit like saying that fuel quantity must be measured in Kg.
I have read some new (< 10 yrs old) publications that refer to these before-wing control surfaces as foreplanes, but I have read many other (more classical) aerodynamic reference documents that refer to them as canards. Some even refer to the wing-foreplane combination as a canard configuration... This appears to be a European creation - modern US reference literature has yet to catch up.
It's a bit like saying that fuel quantity must be measured in Kg.
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Pedant mode on: if moveable, they are foreplanes, not canards: pedant mode off:
Am I right in thinking that at high AoA canards/foreplanes are much better than a conventional tail as the delta wing can obstruct airflow over the tail inducing some very nasty problems (thinking Javelin?)-or have I got that all wrong?
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I got told by a tame aerodynamics chap at work, that having foreplanes enabled far better maneuverability than a pure delta, and that as the foreplanes produce a lifting force rather than a downforce (as with a conventional tail); then you could get away with a smaller wing and still have good turning performance.
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Conventional delta wings can struggle with control saturation at high incidence. The flaperons run out of authority in pitch and roll. Foreplanes enable the flaperons to operate around their mid position so you don't run out of control authority at the extremes. They also help with trimming across the Mach range. Foreplane/deltas can also achieve performance targets with lower overall masses, helpful if you believe there's a correlation between mass and costs.
Having said that, PN might be closer to the truth i.e. fashion may have a lot to do with it. Quite a few years ago part way through Typhoon development, an aerodynamicist suggested that a foreplane delta probably wasn't the best concept based on the latest thinking. He mentioned a foreplane delta with a tail was the way to go. If you believe the SU30's odder manoeuvres are the future of air combat, he might be right.
EAP
Having said that, PN might be closer to the truth i.e. fashion may have a lot to do with it. Quite a few years ago part way through Typhoon development, an aerodynamicist suggested that a foreplane delta probably wasn't the best concept based on the latest thinking. He mentioned a foreplane delta with a tail was the way to go. If you believe the SU30's odder manoeuvres are the future of air combat, he might be right.
EAP
Last edited by EAP86; 5th Nov 2016 at 10:50. Reason: Corrected the Sukhoi designation. Thanks RP
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