Swept Wing Jets

Lears are not that bad at all. Granted more challenging to fly than a strait wing Citation, or maybe any Citation for that matter I am not sure. Strait wing Citations are very stable, very forgiving in their flying characteristics. Older Lear models like the 20/30 series require attention ALL of the time. They seem to be on the verge of a dutch roll all of the time, even the 55. Losing both yaw dampers would seriously suck. The tip tanks make crosswind landings interesting. Lears are built to, and are fat, dumb and happy to fly fast. Even at 200KIAS down low it feels like you're going slow. They are the closest thing to a military fighter that you can come to in the bizjet world. Especially the 20 series. The wing isn't all that swept, but the size of it, is what makes a Lear challenging as it is happiest when flying very fast.
 
Bandit_Driver said:
Fully stall most commercial transport aircraft and it will not end well. I imagine F-15 and T-38 react differently since they have so much freaking thrust available. They are so generous with the thrust to weight ratio in transport category aircraft. Without doing the math I'd wager it is probably 0.25-0.50:1
Click to expand...

Of course a transport category aircraft can't do that, but that wasn't the point -- the point was that not ALL swept wing aircraft, by definition, have unsavory or dangerous stall characteristics. It completely depends on the aircraft.

FWIW, that's about the same thrust:weight in the T-38, which is nearly a 13,000# airplane with 6,000# of thrust in afterburner.
 
Patrick said:
No kidding!! Arguably those were some of the best minds to ever grace engineering (1950's and 60's aerospace in general), however, both before and after.

As to the Lear, the 20/30 series can be a bit interesting to land if you have fuel in the tips (which you certainly want to try to avoid), but they really don't have much sweep. You do have to somewhat piss them off to get them to Dutch roll. However, they do have a very tiny wing, thus with high wind loading. If you fly the Lear and respect it's limitations, it's a very enjoyable jet to fly.

The later Lears, with evolutions of the Longhorn wing (starting with the 55, then the 31, and continuing with the 40/45 and 60) are significantly more docile.
Click to expand...

Actually started with the 28/29. It's not a real Learjet unless it has tip tanks. Longhorn wing is for wussies.
 
Hacker15e said:
Of course a transport category aircraft can't do that, but that wasn't the point -- the point was that not ALL swept wing aircraft, by definition, have unsavory or dangerous stall characteristics. It completely depends on the aircraft.

FWIW, that's about the same thrust:weight in the T-38, which is nearly a 13,000# airplane with 6,000# of thrust in afterburner.
Click to expand...

0.50:1 is a bit optimistic for transport jets with any load. 767-300ER weighs 412,000# at MTOW, with a max blast of ~120,000#. Even the venerable 757-200 has ~80,000# for a jet that weighs 255,500#.

The increase in inertia is enough to cause problems in larger jets, too.
 
dasleben said:
The increase in inertia is enough to cause problems in larger jets, too.
Click to expand...

Definitely, but again that wasn't the point of my post....we were talking about Lears, IIRC, which are closer in weight and performance characteristics to a fighter than a 767. :)
 
Inverted said:
Lears are not that bad at all. Granted more challenging to fly than a strait wing Citation, or maybe any Citation for that matter I am not sure. Strait wing Citations are very stable, very forgiving in their flying characteristics. Older Lear models like the 20/30 series require attention ALL of the time. They seem to be on the verge of a dutch roll all of the time, even the 55. Losing both yaw dampers would seriously suck. The tip tanks make crosswind landings interesting. Lears are built to, and are fat, dumb and happy to fly fast. Even at 200KIAS down low it feels like you're going slow. They are the closest thing to a military fighter that you can come to in the bizjet world. Especially the 20 series. The wing isn't all that swept, but the size of it, is what makes a Lear challenging as it is happiest when flying very fast.
Click to expand...

More hangar tales not even close to the truth. I used to disengage they Y/D way out and never had any issues. 20/30 Learjet's handled crosswinds great. Again, never any issues landing them in severe crosswinds on either a dry or wet/snowy runway.
 
Hacker15e said:
Definitely, but again that wasn't the point of my post....we were talking about Lears, IIRC, which are closer in weight and performance characteristics to a fighter than a 767. :)
Click to expand...

One of the runs I used to fly was in a Learjet 23. One of the legs was from DSM to OMA. This leg only had around a 100 lbs of checks onboard. The aircraft had a BOW of just over 6000 lbs and I had 2500 lbs of gas for a TOGW of 8600 lbs. With each engine put out 2850 lbs of thrust, it would really get up and go.
 
Hacker15e said:
Definitely, but again that wasn't the point of my post....we were talking about Lears, IIRC, which are closer in weight and performance characteristics to a fighter than a 767. :)
Click to expand...

True, true. I have gotten to fly the 767-200ER empty, though. 110,000# thrust with the -300ER wing, at about 260,000#. That VSI pegs at 6000fpm on a normal takeoff.
 
A-300F4-622R said:
More hangar tales not even close to the truth. I used to disengage they Y/D way out and never had any issues. 20/30 Learjet's handled crosswinds great. Again, never any issues landing them in severe crosswinds on either a dry or wet/snowy runway.
Click to expand...

No hanger tales there buddy. The 35 we fly will Dutch roll if you look at the instrument panel funny.
 
seagull said:
Key is proper training. First, will say that the Lear does not much sweep, not the effects of the sweep are less than some other issues. As for higher sweep, it is important to really understand the dynamics. Now, you can "get away" with pretty much the same techniques as other aircraft 99.9% of the time, but if you find yourself in that last little corner-point, those same habits that seemed so reliable will kill you -- fast.
Click to expand...

Exactly. Not that I've ever found myself in that corner.

But yeah, basically it comes down to don't stall it.
 
Remember that the 40/45, (and soon 70/75 and 85) are actually Bombardier and have very little in common with the legacy Learjets other than the shape of the windshield. They are an entirely different airplane... all together!
 
I will readily admit I am out of my league on this one but...

Doesn't it stand to reason that a thorough knowledge of aerodynamics associated with the particular wing/airframe is warrant enough to be able to fly it? Of course I am making some assumptions when I say that

(IE. OP has jet time, etc...)

While it is clear that swept wing jets behave very differently in particular regimes than straight wing airplanes I think the commonalities with regard to swept wing airplanes is that the speeds for low speed regimes are typically higher.

I'm not sure anyone would have the cajones to intentionally stall a transport category jet so I'm not sure why there would be a disparity between swept/straight wing airplanes?
 
rwgb1984 said:
I'm not sure anyone would have the cajones to intentionally stall a transport category jet so I'm not sure why there would be a disparity between swept/straight wing airplanes?
Click to expand...

I'd sure like to play around with it in the sim.
 
You must log in or register to reply here.
Back
Top