New winglet design

[Baker]

Well it is a bit of an ugly duckling is'nt it.

Most of my ultralights were flying wings. One was very stable and one was very unstable. Once one learned to fly it the unstable one was more capable and in many ways safer. I had two ULs that were flying wings w a fwd mounted elevator. Most called them canards but they could only be considered such below trim speed as then the elevator then became a wing....producing considerable lift. They were very efficient. I could fly over 100 miles w less than 5 gallons of gas and climb 1400 fpm at 40mph. At a 60 degree banked turn I could still climb about 500fpm. That was a very fun maneuver. Crank it over ....point the wing at a point on the ground about 200' below and just revolve around it. I'm gett'in excited just think'in about it.

OMAC is for Old Man Airplane Company and they were working on a canard about the size of a Cessna Citation. Had a fairly large canard wing. But in commercial aviation I think the stability of the tail is required for flexibility in payload position ...CG. With a canard flying slowly it's pitch control surface is providing lift. That's why they are so efficient. With a tailed AC flying slowly the tail is creating tremendous drag. But flying fast the tail could be providing lift. Does anybody know or think that could/would happen? If so the tailed AC (it would seem) could be as efficient as a canard but then no AC flying fast can be efficient. But that seems to be so w airliners flying fast at high altitude.

Marin what I asked about was how high CAN they fly .....not how high they should fly w passengers ect. What if you just opened the throttles and observed at what altitude you could'nt go any higher at any angle of attack?


We were posting at the same time. Thanks very much John .....no not too much info at all. Very interesting stuff we UL pilots are totally unaware of for obvious reasons. So you use power to recover from a stall Hmmmmm. With ULs we just dive our way out ....w enough altitude or die if not. I've never died. Thanks John.

You still use pitch to recover from a stall....you have to...but at lower altitudes you have a vast amount of power and if you are not fully stalled(imminent stall) you can power out of it and that is usually the way it is taught al though that line of thinking is changing. There is an increased stall awareness(and training) due to Air France over the Atlantic and the Q400 in Buffalo...both events where the pilots lost control.

Eric, one of my sim instructors got the airplane(767-400 sim) to stall with the nose pointed straight at the ground!!! We were in the low 20s and he had to do some serious maneuvers to get it into that state...basically a split S. But there we were pointed straight at the ground with a windshield full of Earth and the wing was not flying. Do you know how hard it is to push the nose over in that case. Every fiber in your body says to raise the nose because the ground is rising up right in your face. Anyway, it was a wild ride. We recovered below 10000ft with the structural integrity of the airplane in question....it was a sim!!!

 

[markpierce]

For us coots, it is hard work to get airborne.

 

[Marin]

Eric-- From an aircraft manual I have.....

"One factor that most people overlook when talking about this subject is aircraft pressurisation.* Most civilian large aircraft won’t pressurize the cabin to more than 6 or 8,000 ft.* If the cabin pressure remains at, say 8,000 ft, as the the aircraft climbs, the pressure differential becomes greater and greater.* If the structure is not strong enough to whithstand these pressurs, it will catostrophically fail.* The 737 has a service celing of 41,000 ft.* Theoretically, the engines have plenty of power to create lift and climb higher, but due to the cabin pressure limitations, it it were to go much higher, the structure would catastrophically fail.* This is true for most larger narrow- and wide-bodied aircraft."

 

[FF]

"Theoretically, the engines have plenty of power to create lift and climb higher, but due to the cabin pressure limitations, it it were to go much higher, the structure would catastrophically fail.* This is true for most larger narrow- and wide-bodied aircraft.""

The various saftys will prevent the cabin from overpressure, and many ferry flights used to be done by accepting a higher cabin altitude by the crew.

No pax on board.

FF

 

[Baker]

The various saftys will prevent the cabin from overpressure, and many ferry flights used to be done by accepting a higher cabin altitude by the crew.

No pax on board.

FF

^^^^^^^^^^^^THIS^^^^^^^^^^^^^^^^

And FAA certification states a max cabin altitude of 8000ft at max certified service ceiling. That gives a differential pressure of about 8.5 PSI. I think the 737NGs pressure relief is at 9.1...if my memory serves me...which it generally doesn't!!!

 

[SomeSailor]

On our 787 the max is 9.4 psid, holding the cabin altitude at only 6000 feet at a max cruise of 43,000 feet.

Don't try that with an aluminum airplane.

 

[Nomad Willy]

Baker what a high strung stall sim.
That's a rush in a hang glider too.

What I want to know about the airplanes is how high will they fly given just the airframe and engines? All that other stuff aside. 60000'?

I went to 12500' in one of my ultralights and know it could have gone much higher but it's just too cold. A friend of mine went 21000' in an UL that had a ho-hum climb rate compared to mine but he set a world record. Obviously I could have broken it but he was in the business and needed the notoriety much more than I.

 

[Baker]

Baker what a high strung stall sim.
That's a rush in a hang glider too.

What I want to know about the airplanes is how high will they fly given just the airframe and engines? All that other stuff aside. 60000'?.

No telling...are you asking totally stripped down??? Again, no telling. The 767-200 is the hotrod of our fleet. But if I said a number it would be total speculation. An empty 762 with minimal fuel could likely make 50,000....dunno about 60...

 

[SomeSailor]

How high can they fly, or high will they fly. Two slightly different questions. One of the more challenging aspects of flying the 787 high was actually the ability to meet regulations. An aircraft flying at FL400 must be able to descend to FL250 within 2 and half minutes in an emergency. This was very problematic for the 787. The wing is so efficient, it was tough doing that without exceeding speeds.

Boeing (and Airbus for the A380) had to pursue exemptions to present rules to get the cruise altitude they have now. I suppose theoretically something up at FL450 would be possible if you could talk the computers into it.

 

[Baker]

Here ya go Eric. I was thinking about you and our conversation as I was flying to Cancun the other day. As you can see, there is a 30 knot window between the highspeed buffet and the low speed buffet. That sounds like a lot but that is only 15 knots wither side. We were within 1000ft of the computed max altitude with a true airspeed of 445 knots.

 

[Nomad Willy]

John,
Never flown that fast nor have I ever seen those two instruments on the left.

The 30 knot window is indeed very narrow. Probably like flying an UL 1.5 knots above stall. At times that was easily done and all the ULs I flew would promptly and easily recover from a stall anyway....in stable air.

You must be very dependent on stable conditions at that high altitude but surely there must be wind sheers up there.

Now that you've shared this stuff w me I may not fly again.

 

[FF]

Fear not!! Flying can still be exciting.

The Airbust folks have a new deal, Wing spar cracks in the cattle car 380.

Lots better than the tail falling off!

 

[Baker]

John,

Now that you've shared this stuff w me I may not fly again.

And a "Heavy" widebody is barely flying right after takeoff. When I was flying the 767-400, at Max Gross T.O. Weight(450,000lbs) after we got the gear and flaps up and at 250kts(speed limit below 10,000ft, the stall buffet margin on the speed tape was at about 240kts!!!!...in heavier aircraft(747-400) they have to get a waiver to go faster below 10000ft. Low altitude stalls are quite different from high altitude ones....