I heard many times and again in the loudest jet thread that lear jets are very loud. I have heard one only once and I agree that they are extrememly loud. My question is are the loud lear jets only the older models, or are all lear jets loud, but just not as common these days.

We operate a couple of these rockets, all are Stage III and I've never really noticed that they are that noisy.
At least you don't notice it as a pax.

Rgds
OO-AOG

Yeah, all of em I've seen sound like a coyote in a garbage can with a stereo blasting inside. Really noisy!!!

All older 20 series LearJets use GE turbojet engines... certainly quite loud. The newer 30 series, the 55 use Garrett TFE-731s turbofans and the 45 and 60 use a new generation Pratt turbofan.

All the 20 series lears had CJ's on them, which is a straight turbo jet and very loud. You can still hear a 25 when they are 20 miles down range. Also, advancing the thrust levers = pushing you back in your seat. I love those old lears. The newer lears have mostly 731's which is a bypass fan and therefore much quieter and much more fuel efficient. The downside is they don't have as much "bang for your buck." They feel underpowered and sluggish by comparison and don't have the climb performance the 25 did.

From my perspective (3,000 hrs) of Lear time...
20 and 30 series Lears have the best technology that money could buy in 1958. The 20 series have the NOISEY turbojets and the 30s have the much quieter turbofans. That accounts for the differences in their external noise levels. The internal noise level is dependent upon cabin soundproofing and the type of windshield heat they have. However, they all (except for the 31s and a few of the late 35s) have bleedair windshield heat which is EXTREMELY NOISEY when it is used (nearly every flight starting about 45 minutes prior to descent - to keep the windshield from fogging after the airframe is cold soaked.) I've been in a few 35 freighters that were absolutely numbing when it came to noise levels, but the corporate 35s I've flown were for the most part very nice from a noise perspective. (From a comfort point of view, the biggest problem with them was heat stratification in the cabin - at night when it was cold-soaked the cabin/cockpit floor got extremely cold and your feet would go numb. Some operators installed electric heaters in the floor to combat the problem.) I've got to disagree a little bit with what Twotterwrench said about the sluggishness of the 30 series aircraft. It is true that they don't have the get up and go of the 20 series, but they are usually flown at weights up to 3000 pounds more. When flown at equal weights the differences are minimized. However, the 20s still have the advantage in the climb. That being said, I'll take a 30 over a 20 any day - I like not having to fly around with a "fuel emergency" in progress.  

It is amazing. A 25 can out whine a 747 on the role easily. You really notice it when you crawl under the lefthand motor to pull the GPU plug when it is running.

Lot of noise in that motor if you just let it go and don't hold it back..

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