Learjet 35A

[737guy1 39]

I have noticed some performance paramaters that do not seem quite right.  I could be wrong, but thought I would mention them here incase it can lead to a positive change.

 

The turbine temp goes into red with the fan percent being just over 80.  How do we use the 95 percent or so that would be conceivable used for takeoff if the temp is off the marks on the gauge? 

 

I also read a general stat that said the Lear 35A needs just over 10,000ft of runway to takeoff at 5,000ft altitude and 25c outside air temperature.  I Tried this out at KDEN.  I went to 18,000lbs GW, throttles to 95 percent (well past redline on the temp gauge) and it took off in about half the 10,000ft distance needed.  I tried this again with the power only at 80 percent and got a more reasonable takeoff roll.  Could it just be over powered some in the sim? 

[Flying Penguin 44]

I think you've answered your own question to an extent.  If you can only keep temperatures in the green at 80%, and get near the stated take off roll by doing so, then that's probably your takeoff power setting right there....

 

I don't have figures to hand, but rapid over temperature at high power, low speed, low altitude is a pretty common theme on early Lears, remember they were ridiculously overpowered for what they were.  Both the decent sims of the LJ24 I've seen display similar characteristics in terms of reduced power take offs and being able to easily over speed/temp on take off, so the fact that the LJ35 does the same would seem reasonable.  As you get to cruise altitude you can start stretching the Lear's legs a bit more and over-temperature situations become less of an issue.

 

Not saying it isn't overpowered (you would need more hard data to prove that one way or another), but given the aircraft in question is a bit of a hot-rod, at least as far as bizjets go, it's not necessarily something I'd be concerned about as it would seem to be in the right ballpark.

[737guy1 39]

 

Cool video to watch one way or another.

 

From watching several videos I have never seen any of the pilots taking off with 80 percent on their fan gauge.  And the corresponding temp is never over the redline.  Of course I don't know the air temps they're flying in.  I would suppose that you would have a higher chance of overheating on takeoff on a hotter day vs colder.  I was redlining with outside air at 77 farenheit.

[Flying Penguin 44]

Yep, to be fair, I've looked at a few more vids and there may be a point.  They seem to be using about 90% thrust or thereabouts.

 

Would be interesting to understand if it varies between the -2B and the -2C engine variants, the ones in videos I could find data on had the -2C engines installed (which was a post-manufacture mod), this does increase the temperature limits somewhat.

[ryanbatc 12,819]

What's the cruise speed of this thing? And high speed cruise ?

[MartinRex007 390]

Same problem it seems that LHC Learjet 24 has?

[737guy1 39]

Same problem it seems that LHC Learjet 24 has?

 

Not nearly as pronounced as the Lionheart one. 

 

I'm not a real wold pilot.  I have never been in a real learjet so these are just my observations from viewing footage from inside these aircraft.  They are great performers. I just feel like its easy to get too carried away with the power.  The fuel consumption is high at take off thrust too.  I think it is probably just a limitation with FSX to get it completely right because fuel consumption seems accurate on the ground at idle and at cruise with a cruise power setting.

[MartinRex007 390]

That's good to know, I think in order to get the top end performance that a Learjet can do, the low end performance might suffer a bit, perhaps a limitation of FSX/P3D. Not being able to go much above 80% thrust on take off might be the compromise, I believe Bill over at LHC alluded to this, but don't quote me :wink:

[737guy1 39]

I've made some of my own adjusting to the .air file to bring it down to what I feel is more accurate.  But I think everyone probably has their own taste.

[CW46 101]

As a former Lear 35 pilot the N1 takeoff thrust setting would be in the 93.x to 95.x range and you would never exceed temp limits that low of a N1 unless the was a problem with the engine fuel computers.As I recall I think 862C was start limit, around max 830C for takeoff, we would use 795C for climb to be kind to your engines.BTW way N1 is the fan speed and is computed for takeoff thrust not the turbine speed.I was skimming thru the product manual and there are a few system misconceptions stated there.Flight plan cruise was 440 KTs about .78 mach depending on upper air temps, 430's to 460kt. Figure 1500lbs 1st hour fuel burn,1200 2nd,1100,1000 as she goes. 4+45 would be as far as we would go with it in good weather on the other end.Not to say your rear end would like it.

 

Lear's were good performers in the day, the 35 could stretch the range, longest flight I made was SFO to TEB non stop but that is not the norm.We were doing great until they dropped us down to FL230 west of New York and then your fuel flows go up.The Lear 25 was a rocket when you were light but was a pain to operate in congested airspace like New York to Florida. We would taxi out on one engine because of departure delays,fire up the other one and plead with ATC for higher as soon as possible after takeoff to conserve fuel.They need to go high for range and it will eat your lunch down low.I just be came aware of the Flysimware 35 model may have to get that painted in the old corporate colors.

[MartinRex007 390]

Gary, thanks for the insight and if you decide to buy her let us know what you think!

 

Cheers

Martin

[737guy1 39]

As a former Lear 35 pilot the N1 takeoff thrust setting would be in the 93.x to 95.x range and you would never exceed temp limits that low of a N1 unless the was a problem with the engine fuel computers.As I recall I think 862C was start limit, around max 830C for takeoff, we would use 795C for climb to be kind to your engines.BTW way N1 is the fan speed and is computed for takeoff thrust not the turbine speed.I was skimming thru the product manual and there are a few system misconceptions stated there.Flight plan cruise was 440 KTs about .78 mach depending on upper air temps, 430's to 460kt. Figure 1500lbs 1st hour fuel burn,1200 2nd,1100,1000 as she goes. 4+45 would be as far as we would go with it in good weather on the other end.Not to say your rear end would like it.

 

Lear's were good performers in the day, the 35 could stretch the range, longest flight I made was SFO to TEB non stop but that is not the norm.We were doing great until they dropped us down to FL230 west of New York and then your fuel flows go up.The Lear 25 was a rocket when you were light but was a pain to operate in congested airspace like New York to Florida. We would taxi out on one engine because of departure delays,fire up the other one and plead with ATC for higher as soon as possible after takeoff to conserve fuel.They need to go high for range and it will eat your lunch down low.I just be came aware of the Flysimware 35 model may have to get that painted in the old corporate colors.

So good to hear your imforation as a pilot of this aircraft!  I too would be very interested to hear of your impressions of this addon should you decide to purchase it.

[ryanbatc 12,819]

What's MMO on this thing?

 

Can someone please (please?) make some screenshots - I'd like to see how good this can look. The dev ones aren't that great

[737guy1 39]

My pics won't do much good. I can tell you that the exterior modeling is very real looking. Proportions are all dead on. The texturing is actually really pleasing in my opinion. The cockpit proportions really give you the feel of being in a tight Lear cockpit. I don't have a single complaint about the modeling or textures.

[CW46 101]

What's MMO on this thing?

 

Can someone please (please?) make some screenshots - I'd like to see how good this can look. The dev ones aren't that great

 

.82 mach