Why aren't modern transport aircraft canards?

[Morne]

So I was thinking about the two newest transport aircraft, namely the A-380 and 787. Both utilize composites a great deal. Yet both still have conventional wing and tail configurations rather than a canard. If all the canard flyer claims of greater efficiency (both surfaces lift as opposed to a conventional tail pushing down) are true then why aren't new transport category aircraft designed as canard birds?

 

[Velocity173]

That's because canard aircraft aren't as efficient as a comparable conventional design. Just look up canard aeronautics or canard efficiency online and you'll see the disadvantages of a canard design.

My Velocity has better performance than a SR-20 only because it has a smaller wetted area. The disadvantage of being less pitch stable kinda offsets the speed advantage.

You can bet a canard would have won Reno long ago if they were more efficient than a conventional design.

 

[ClimbnSink]

Never forget about momentum. Amend the public expects their jetliners to look a certain way. Not saying canards are more efficient, just that the deck is stacked against such a visible change. If I ran an airline and my competitors went to a more efficient canard fleet I'd run ads comparing them to John Denver's last ride.

 

[poadeleted21]

Never forget about momentum. Amend the public expects their jetliners to look a certain way. Not saying canards are more efficient, just that the deck is stacked against such a visible change. If I ran an airline and my competitors went to a more efficient canard fleet I'd run ads comparing them to John Denver's last ride.

There's a hint of truth to that. I know people who dreaded riding in those terrifying tiny little Dash 8s that Horizon Air uses. I've had more than one person tell me about riding in one after asking "Have you ever flown in a small plane before?"

 

[stratobee]

Plus adding flaps to a canard is problematic. And without flaps an A380 size canard would need Cape Canaveral style runways to land at.

 

[Silvaire]

Just look at how many jet ways they smash into without canards and try to imagine how many they would smash into if they had them.

Truth is: there's no slam dunk with canards like some might have you believe. If there were we'd see a lot more of them than we do. There's not much of anything that hasn't been tried in aviation and canards aren't anything new, been around a long time.

 

[JimNtexas]

Boeing seriously considered making the Sonic Cruiser:

The Cruiser was very fast, but got poor gas milage. Had Boeing made some they probably would have wound up like the Convair 880/990, which was essentially a transport version of the B-58. Fast, but too expensive.

 

[Henning]

However, a hybrid using a canard in conjunction with a standard wing and tail proves out very efficient and handles quite nicely. If you ever get a chance to fly a Katmai 182, you'll be quite impressed.

 

[Rex Kramer]

Don't forget they have to fit into the flow of contemporary airport design. Jetbridges, cargo loading/unloading, etc...

 

[Henning]

Don't forget they have to fit into the flow of contemporary airport design. Jetbridges, cargo loading/unloading, etc...

True, but accommodations are pretty easily made, look at the A-380, almost none of the prior infrastructure would work with it, lots of modifications were needed, but if the numbers crunch right, it happens.

 

[kkoran]

Boeing seriously considered making the Sonic Cruiser:

The Cruiser was very fast, but got poor gas milage. Had Boeing made some they probably would have wound up like the Convair 880/990, which was essentially a transport version of the B-58. Fast, but too expensive.

Other than having four under-wing, pod-mounted engines and being built by Convair, how was the 880/990 essentially a transport version of the B-58?

 

[Skip Miller]

(both surfaces lift as opposed to a conventional tail pushing down)

This aviation canard (hah!) is not true. Yes it probably is true at light weights but when an airline is full of pax, luggage, and fuel (moving the cg aft) it may not be true... in which case the supposed advantage of the canard design isn't.

-Skip

 

[roncachamp]

The Cruiser was very fast, but got poor gas milage. Had Boeing made some they probably would have wound up like the Convair 880/990, which was essentially a transport version of the B-58. Fast, but too expensive.

I don't see much similarity between the Convair 880/990 and the B-58.

 

[SixPapaCharlie]

Never forget about momentum. Amend the public expects their jetliners to look a certain way. Not saying canards are more efficient, just that the deck is stacked against such a visible change. If I ran an airline and my competitors went to a more efficient canard fleet I'd run ads comparing them to John Denver's last ride.

This is sadly true. Not sure on the physics of canards but I had a friend that designed seats for commercial airliners. He said the reversed seats like in the bulkhead section of the 737 increased survivability in a plane crash significantly. I asked why not install all the seats backward. He said "people won't like it because it would seem unusual".

 

[N801BH]

There's a hint of truth to that. I know people who dreaded riding in those terrifying tiny little Dash 8s that Horizon Air uses. I've had more than one person tell me about riding in one after asking "Have you ever flown in a small plane before?"

Funny you mention that.... Just yesterday I went flying and as I taxied by the commercial ramp /terminal there was a Dash 8, and Q 400 and a Delta RJ parked side by side.. The Q was by far alot bigger then both and the Dash 8 was a little bigger then the RJ.... My guess is the general public hate props and love to see jet engines.....

It is all about perception.......

 

[JGoodish]

Never forget about momentum. Amend the public expects their jetliners to look a certain way. Not saying canards are more efficient, just that the deck is stacked against such a visible change. If I ran an airline and my competitors went to a more efficient canard fleet I'd run ads comparing them to John Denver's last ride.

That's fine, so I'll run my airline more efficiently and make more money than you do. Your commercials won't keep people away if I can offer them a better deal without becoming insolvent. Only fools cater to incorrect perception.


JKG

 

[kyleb]

Even Burt Rutan will tell you that the canard platform is less than ideal. The interactions between the airflow reduce the efficiency of the main wing. The other compromises - difficulty of installing high lift devices, excess stall margin required on the main wing, etc. cause runway length problems.

 

[Velocity173]

Compare the specs on a Velocity XL FG to an SR-22. You'll see they have almost the exact same performance but yet the Cirrus does it with a bigger cabin and slower min speed. The high wing loading on the canard creates unwanted induced drag and the airflow from it hits the main wing.

Now there are some efficient canards (Klaus Savier) out there but it's due to other mods than the canard. You're not going to see too many canards out running a tractor design of comparable HP. Of course the XB-70 was fast but I think it had more to due with the 6 engines and 174,000 lb of thrust than the canard.

 

[Velocity173]

Boeing seriously considered making the Sonic Cruiser:

The Cruiser was very fast, but got poor gas milage. Had Boeing made some they probably would have wound up like the Convair 880/990, which was essentially a transport version of the B-58. Fast, but too expensive.

This is sadly true. Not sure on the physics of canards but I had a friend that designed seats for commercial airliners. He said the reversed seats like in the bulkhead section of the 737 increased survivability in a plane crash significantly. I asked why not install all the seats backward. He said "people won't like it because it would seem unusual".

I think passenger comfort might have something to do with it as well. I've read people are more prone to air sickness seated facing aft. Not sure about the science involved in that though. Personally I've sat facing to the rear on a C-2 flying out to the Stennis and I was fine. Lack of windows was the only problem.

I know both the White Lightning and the Wheeler Express had aft facing seats for more shoulder room. Makes for an excellent use of space but I've never read any reports as far as passenger comfort with that configuration. Better crashworthiness or comfort????

 

[jonnyjetprop]

Don't canards have issues with icing too? It's the change in the aerodynamics when the airfoil is contaminated.

 

[X3 Skier]

This is sadly true. Not sure on the physics of canards but I had a friend that designed seats for commercial airliners. He said the reversed seats like in the bulkhead section of the 737 increased survivability in a plane crash significantly. I asked why not install all the seats backward. He said "people won't like it because it would seem unusual".

The USAF used to run a shuttle service between Wright-Patt and Andrews back in the 60's using T-29/C-131's with rear facing seats.

Cheers

 

[akpilot907]

It all comes down to.... $$$$$ if you haven't looked at the world economy recently, it's not so hot!

 

[Dr. O]

Canards quit flying when iced.
They get squirrelly in the rain.
Rutan even had an article where he showed the wife how his bird lost speed when it ran through a rain shower and gained it back once the canard dried.
A pure canard does not have enough positives to overcome the negatives.
A three surface planform does a lot better but even a small bit of rime ice can still be significant.

 

[Sac Arrow]

My understanding is that in theory, a canard is more efficient in that both surfaces are positively loaded, vs. the need for the main wing on a normal airplane to overcome some tail downforce. However, in order to ensure that the canard will stall before the main wing, it's necessary to oversize the main wing proportionately to the canard, which creates offsetting drag.

I suppose in a high performance fighter jet with vertical acceleration capability, stalling the main wing isn't quite as big of a deal because you can fly out of a nose high attitude stall, but typical GA and transport aircraft don't have that luxury.

I would imagine a best case canard stall is similar to a tail stall in a conventional aircraft - loss of pitch control until you get enough airspeed back.

 

[JohnAJohnson]

The USAF used to run a shuttle service between Wright-Patt and Andrews back in the 60's using T-29/T-131's with rear facing seats.

Cheers

The C-5 upper deck airline seats all face aft, and any time airline seats were installed in C-141s, they faced aft. I'd imagine this is true for C-17s too. Never seemed to be a problem with excessive pukage in these planes that I can remember.

 

[Capt. Geoffrey Thorpe]

Many people would consider it to be an odd duck.

 

[JimNtexas]

Other than having four under-wing, pod-mounted engines and being built by Convair, how was the 880/990 essentially a transport version of the B-58?

It was the only other airplane I know of with four J-79's. It was the fast civilian airliner ever made , excluding the Concorde.