Difference betweeen a Lear 31 and 31A?

[Palerider957]

Can anyone tell me what the major diffrences between the 31 and 31A are? What are the general impressions of the 31? What are real altitude, range, and profile numbes?

As always, thanks for your help.

 

[h25b]

Can anyone tell me what the major diffrences between the 31 and 31A are? What are the general impressions of the 31? What are real altitude, range, and profile numbes?

As always, thanks for your help.

The 31's that I have flown were basically 31A airframes with the old 35 avionics/systems in them. In other words, no glass, no fuel heaters, no digital nosewheel steering. They had the extended range aux. fuel tank however, but this just cuts down the already limited baggage area.

Not bad as long as you are flying pretty much all day trips, otherwise anything more than like 4 people with bags is out of the question. Not due to weight, but just cubic volume limitations.

 

[Lead Sled]

Actually, as I remember the major difference was that the 31 did not have a mach trim system and its Mmo was something like .75M. The 31A had the mach trim system and a higher Mmo. However, it's been a long time and my manuals are buried so hopefully someone can correct me if I am wrong.

I was never all that impressed with the 31 or 31A. Sure, they'll climb a bit higher than a 35, but basically if you want 31 performance out of a 35, just fly it at comparable weights. At least with the 35 you have the option of going out with 1,300 lbs (about an hour's worth) more fuel. The problem with 35s is that they're starting to get a little long in the tooth.

Both airplanes share the same miserable baggage issues - it's behind the bench seat. A 35 is a classic airplane and still has a lot of life, but I'd think long and hard about recommending one to the boss. As long as you don't need the range a Citation V would probably be a much more user friendly airplane today.

'Sled

 

[XTW]

Avatar

Great avatar Sled!

 

[h25b]

Actually, as I remember the major difference was that the 31 did not have a mach trim system and its Mmo was something like .75M. The 31A had the mach trim system and a higher Mmo. However, it's been a long time and my manuals are buried so hopefully someone can correct me if I am wrong.

You are correct on this. I have forgotten about that and it aside from the absence of digital nosewheel steering, it is one of the biggest pains in the rear of the straight 31's...

 

[Palerider957]

Thanks for everyones info.

 

[Lead Sled]

I got to play around in FlightSafety's very first 31 sim when we were there for a 35 recurrent. The instructor wasn't too kind when it came to the 31 - his thoughts were that Lear went way too far in their attempt to turn their 35 into a Citation. The 35 was a GREAT airplane to fly, but it also demanded that the pilots knew what they were doing. Their chief competition (then and probably now as well) was the Citation 500 series airplanes. The Citations fly ok, but almost every one describes them as turbojet-powered 182s for a reason - they're not very demanding.

Lear essentially put the Lear 28/29 Longhorn wing on a 35. Added those UGLY delta fins to be able to eliminate the dual yaw-damper requirement and to give it the stall characteristics of a Citation and while they were at it, they reduced the Mmo to eliminate the need for the mach trim system. In short, the eviserated a tiger and turned it into a kitten. Customers bought Lears to go fast and people didn't like the fact that the straight 31 had an Mmo of just .75M. It wasn't very long before Lear went back and reinstalled the mach trim system so thay they could raise the Mmo back up to where it is now. (FYI - the Mmo limit is due to the horizontal tail design, not the wing, and is shared by all 20 and 30 series Lears.)

I alway thought that it was strange that Lear put the delta fins on their airplanes as a bandaid fix so that they could enhance their stall recovery and yaw dampening qualties - similiar to what Beech had to do to the 1900. The Lear 45 was touted as a "Clean Sheet" design. If it truly is, why keep the bandaids? Why not design a proper tail for the new airframe? You can probably tell, I'm not a real fan of the current Lear line.

'Sled

 

[h25b]

I got to play around in FlightSafety's very first 31 sim when we were there for a 35 recurrent. The instructor wasn't too kind when it came to the 31 - his thoughts were that Lear went way too far in their attempt to turn their 35 into a Citation. The 35 was a GREAT airplane to fly, but it also demanded that the pilots knew what they were doing. Their chief competition (then and probably now as well) was the Citation 500 series airplanes. The Citations fly ok, but almost every one describes them as turbojet-powered 182s for a reason - they're not very demanding.

Lear essentially put the Lear 28/29 Longhorn wing on a 35. Added those UGLY delta fins to be able to eliminate the dual yaw-damper requirement and to give it the stall characteristics of a Citation and while they were at it, they reduced the Mmo to eliminate the need for the mach trim system. In short, the eviserated a tiger and turned it into a kitten. Customers bought Lears to go fast and people didn't like the fact that the straight 31 had an Mmo of just .75M. It wasn't very long before Lear went back and reinstalled the mach trim system so thay they could raise the Mmo back up to where it is now. (FYI - the Mmo limit is due to the horizontal tail design, not the wing, and is shared by all 20 and 30 series Lears.)

I alway thought that it was strange that Lear put the delta fins on their airplanes as a bandaid fix so that they could enhance their stall recovery and yaw dampening qualties - similiar to what Beech had to do to the 1900. The Lear 45 was touted as a "Clean Sheet" design. If it truly is, why keep the bandaids? Why not design a proper tail for the new airframe? You can probably tell, I'm not a real fan of the current Lear line.

'Sled

While I don't share any particular fondness for the Learjet 31a. All of these "bandaid fixes" that you mentioned do work. They did achieve the desired outcome and the 31A does what it was supposed to do.

As for the Delta fin, it fixes the main complaint I had with the 35. I hated fighting those dual yaw dampers and it is nice to have an airplane that is now so stable it no longer even really needs the dampers.

When speaking of the 31A they didn't take the tiger out of anything..

 

[Lead Sled]

While I don't share any particular fondness for the Learjet 31a. All of these "bandaid fixes" that you mentioned do work. They did achieve the desired outcome and the 31A does what it was supposed to do.

As for the Delta fin, it fixes the main complaint I had with the 35. I hated fighting those dual yaw dampers and it is nice to have an airplane that is now so stable it no longer even really needs the dampers.

When speaking of the 31A they didn't take the tiger out of anything..

The way they put the "tiger" back into the kitten was to limit its weight. In an airplane of that size, 1300 lbs is significant. The 35 is a real scooter if you limit its weight to 17,000 lbs.

I've got 3,000 hours in Lear 35s and I never had an issue with the dual yaw dampers. Perhaps it could be an issue for some operators, but we rode our airplane hard (for corporate) and never had a dispatch issue in 6,000 hours. That's good enough for me.

'Sled

 

[Gulfstream 200]

Sled I love that avatar!