Mach Number

[bullfox]

I downloaded the freeware Saberliner and have been trying to maximize range. I notice that it accelerates to the mach number red line at about .8. I am guessing that I should throttle back to just below the maximum mach number for fuel efficiency. Is that correct?

[MkIV Hvd]

No you should throttle back to get there as soon as possible without over-speeding the airplane. I’m not familiar with Sabreliner performance, but best economy/max range would somewhat slower.

Cheers,
Rob

[DHenriques_]

I downloaded the freeware Saberliner and have been trying to maximize range. I notice that it accelerates to the mach number red line at about .8. I am guessing that I should throttle back to just below the maximum mach number for fuel efficiency. Is that correct?

Generally speaking when dealing with subsonic jets .85 is about it without getting into critical mach number and drag divergence mach numbers. The optimum cruise range for these aircraft will almost always be found either at .85 or slightly below around .78-.83.
Naturally there are always engine and aerodynamic considerations applicable to any specific airframe/engine combination.
If I remember right the wing on the Sabreliner was designed fairly close to the F100 numbers. If so I would say without reading the book that you are pretty safe around .85.
Dudley Henriques

[bullfox]

I'm getting a little more than 2000 nm at 30,000 feet cruise. Doing some research on line the max range is around 2100 nm but there are different numbers for range and fuel capacity. The ceiling is variously stated at 40 or 45,000 feet Should I expect max range at higher altitude? I had to cut the fuel flow scaler in the config file to get over 2,000 nm range.

[DHenriques_]

I'm getting a little more than 2000 nm at 30,000 feet cruise. Doing some research on line the max range is around 2100 nm but there are different numbers for range and fuel capacity. The ceiling is variously stated at 40 or 45,000 feet Should I expect max range at higher altitude? I had to cut the fuel flow scaler in the config file to get over 2,000 nm range.

Jets and numbers are finicky. Without the book if you go high and fast you can easily get into a "coffin corner" situation.
I'd spend a bit more time researching the numbers. I'd be guessing if I tried to nail something down without the book.
DH

[ratty]

I found a downloadable copy of the Sabreliner 65 manual here: https://vdocuments.net/sabreliner-65-fs ... ml?page=55, that might have the info you need. There are others available.

[AKar]

According to TCDS, the MMO of the Sabreliner is .765 for the early models, and .800 for later ones with JT12s. The maximum operating altitude is 45'000 ft. The model -65, the one with Garrett TFE731 turbofans, has its MMO at .825.

While I've got no clue whatsoever of the specifics of Sabreliner's preformance, usually the Mach numbers for maximum range in still air are more than .1 shy from MMO, unless 'low knots limited' due to high altitude. Out of memory, and perhaps being a way off here, the max range cruise Machs for A320ies, that flat out at M.82, are in the high .60ies or low .70ies, depending on the weight. Again, if I recall correctly, can't check out right now, but that's the usual ballpark.

-Esa

[bullfox]

OK, on a flight from Sedona, Arizona to Medford, Oegon at fl 35 with just about dead air I kept the mach number as close as I could keep it to mach 7.5 and I got the equivalent of 2800 nm range which is about what I want as I was hoping to be able to fly from Hawaii to the mainland and maybe around the world. I had to lower the fuel flow scaler about 25% in the config file to get that however. The sim has a speed hold switch for the autopilot but it doesn't seem to work right as it just wants to move the throttles to idle. The sim is pretty good but has a few quirks. I give it a bout a B grade. Not too bad, interesting to fly but with some minor problems. Not up to A2A standards.

[AKar]

The sim has a speed hold switch for the autopilot but it doesn't seem to work right as it just wants to move the throttles to idle.

I doubt such an early business jet has any kind of auto thrust. Speed and Mach holds in what comes to the autopilots are climb/descend modes with purpose of keeping the target value by adjusting the climb rate via pitch angle. Why the thrust levers go to idle, I've got no idea. Perhaps it is a descend only mode.

How exactly anything is modeled there, in particular after manual config file changes, I'd take with a good pinch of salt. There have been very few freeware projects with resources to create truly high-end study level simulations that, in fact, even majority of the payware companies tend not to get right in the details.

-Esa

[bullfox]

The Sabreliner is far from perfect. I would rate the quality of the sim as somewhat below what Carenado does. It really seems unfinished. for example some of the tool tips are backwards showing "off" when the switch is set to "on" and many of the usual tool tips are missing. The cockpit has some display artifacts. The codeing is not as stable as it should be. The developer had it as payware on the Orbx site for a while, then took it down to fix some problems, then put it back up. After it had been up as payware for a while MSFS came along and then the developer made all their P3D aircraft freeware and said they would no longer offer any support to any of their P3D products. But the Sabreliner mostly works, looks good externally, and has some interesting quirks to figure out...

I like it because it has all steam gauges. Most of the business jets and airliners nowadays in P3D have glass cockpits. So for a jet with steam gauges that can fly high and fast with relatively long range the price is right.

I don't mess with the A2A aircraft. I take them as an honest and excellent attempt to correctly model a real aircraft. But from most other developers I am willing to do what I can to get out of them what I want in they way of performance since many of them already have other problems.

[ratty]

I tried the Sabreliner and was initially enchanted with it for the same reason: old bizjet with steam gauges. It's a very good looking model and seemed to have promise. I was first turned off by the deck angle with flaps deployed - the nose attitude is way too high. I tinkered with the cfg but couldn't get a result I liked. The more I learned about it the more disappointed I became, which has been my experience with most of that company's models.

There's a reason that I'm pretty much "all A2A all the time".

[bullfox]

I will look at the deck angle and see what I can do. I have a problem with the white ring around some of the gauges sparkling and the same thing with the intersection of the upper and lower panel. Can not completely eliminate it. Also, while it comes with the GTN 750 I can not get it to install in the panel where the inoperative weather radar is. There's probably other problems I'm not knowledgeable to know about.

I had one other airplane from the same developer but it had significant problems also. For freeware the Sabreliner is not too bad.

[MkIV Hvd]

Much to my chagrin, I actually bought the Sabreliner, just before it became freeware. I agree that it's worse than a Carenado airplane, the LAST one of which I bought two years ago and flew for two minutes...I didn't know there was a lower quality level than Carenado...

I too, was hopeful because the exterior graphics are good and that era of business jets is my wheelhouse, but the interior graphics remind of an FS9/FSX transistion era airplane. I didn't notice a particularly high deck angle, but I basically only flew it for one circuit. IMO there should be an award, possibly including cash and media coverage, for flying that airplane around the world...

Cheers,
Rob

[GaryRR]

Much to my chagrin, I actually bought the Sabreliner, just before it became freeware. I agree that it's worse than a Carenado airplane, the LAST one of which I bought two years ago and flew for two minutes...I didn't know there was a lower quality level than Carenado...

I too, was hopeful because the exterior graphics are good and that era of business jets is my wheelhouse, but the interior graphics remind of an FS9/FSX transistion era airplane. I didn't notice a particularly high deck angle, but I basically only flew it for one circuit. IMO there should be an award, possibly including cash and media coverage, for flying that airplane around the world...

Cheers,
Rob

I got the Sabreliner for free. I prefer the Yannick Lavigne/Rob Banting Falcon 50 as freeware bizjet. Just keeps going and going.
Some Carenado editions are okay. In pistons.
PA-31
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Most of the rest are toys.