CRJ 700 Mach hold doesn't work

[xclavex]

Well, I am a pretty well rounded amateur FSX pilot and I know my way around the basics such as takeoff, auto pilot, ILS landings, etc. That said, I cannot for the life of me figure out how to engage the MACH hold setting for the CRJ 700 bombardier plane! I click the MACH button, as logic would indicate that would be the button to enable the MACH hold, but all it does is put a little "MACH" message in green on my little speed/alt/heading indicator screen to the lower left in cockpit view. When I try to raise the speed, it raises only in knots and not in MACH. What am I doing wrong? I don't normally fly this plane (I'm used to the Boeings) and can't use the MACH setting. This is a considerable problem for higher altitude flights. Any help would be appreciated.

[wdscobie]

there is no autothrottle on the real CRJ.

pilots control airspeed using the thrust levers during cruise, descent and landing.


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[cianpars]

I've jsut started flying the CRJ and coudn't work out how to set the rate of climb on the autopilot either.

IAN

[xclavex]

I've jsut started flying the CRJ and coudn't work out how to set the rate of climb on the autopilot either.

IAN

The rate of climb is controlled with the vertical speed slider on the upper right.

[xclavex]

there is no autothrottle on the real CRJ.

pilots control airspeed using the thrust levers during cruise, descent and landing.


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But why is there a "mach" button when it doesn't even do anything then?

[cianpars]

Thanks, I'll look for that next time I fire FSX up.

IAN

[wdscobie]

But why is there a "mach" button when it doesn't even do anything then?

because MS/Aces created a plane mode that looks like, and kinda' acts like a CRJ-700. little about the simulated cockpit function and performance is like real-world.

here is a link to a photo a a real CRJ-700 cockpit. note there is no 'mach' button -

http://www.airliners.net/photo/Unite...nal/0863676/L/

the real-world CRJ-700 has a engine control system that controls/manages thrust for takeoff and climb (FADEC - http://en.wikipedia.org/wiki/FADEC ).

there is no 'speed control' like FS models. as my first post stated the CRJs have no autothrottle (note real world panel picture). in the real CRJ climb speed is managed by the autopilot changing the aircraft's pitch. this is what the 'speed' button does on the real-world panel picture. again, this 'speed control' only works during climb. for cruise, descent and landing the pilot must use the throttles to control speed.


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[freddy]

Mach hold ... FSX default CRJ-700 ... I believe that may be one of the (many) things fixed by Alexander Barthel's "crj_700_gauge_fixes.zip" file available from the AVSIM (www.avsim.com) file libraries. It's in the Gauges section. (I don't think that file is here in the Flightsim.com libraries.)

I can't recall specifically if it actually does fix the mach hold (I'm at work now and don't have access to the release notes, and work's file server prevents me from downloading it to check), but I do recall something about mach getting a mention in the release notes. Nonetheless, for the changes and fixes it gives you, the file is worth installing anyway. The "crj_700_gauge_fixes.zip" package fixes numerous bugs in the gauges of the default Bombardier CRJ-700 and adds some new features including a min/max speed bar in ASI, wind vector to PFD, track line in MFD, added VORs and Airports in MFD map mode, new mouse click spots in PFD and MFD, etc.

Whilst there, you may also consider grabbing Alexander's excellent "learjet_45_enhancements.zip" for the default Learjet which adds map mode to the EICAS display with terrain display, track line, display of approaches, airports, VORs, NDBs and waypoints. This file also adds min/max speed bar, wind vector, VOR2 and radio altitude in the PFD as well as the throttle lever position display in EICAS.

And finally, Alexander's "b737_gauge_fixes.zip" file for the default B737. This package fixes numerous bugs in the gauges and adds some new features such as engine throttle lever position display in EICAS, fixes for various problems with bearing pointers, many other bug fixes in the MFD and PFD, activated LE flap indications and more.

[granath]

I plan to look at those links to fixes for the default jet gauges. Sounds good. I have an additional issue.

The CRJ700 Flight Notes say that typical cruise speed is 0.77 mach. I started the cruise portion of my flight at 21,000 and 250 kts using autopilot with the Speed Hold switch engaged. The PFD displayed SPD in the upper left corner and M0.54 at the top of the speed tape (which I think shows my speed in mach notation).

I clicked the IAS/MACH Setting switch and MACH replaced SPD in the upper left corner of the PFD (although when mousing over the Speed Hold Selector knob it still shows the speed setting in knots). I gradually increased the speed to M0.74, at which point the "aircraft overstressed" message displayed at the top of the screen and FSX reset the flight.

Basically I tore the wings off. Does anyone know what I misunderstood? Seems like I should have been able to safely increase speed until at least M0.77, and probably a little beyond that (don't know what the Do Not Exceed speed is for the CRJ700).

Thanks, G

[djadlib]

With overspeeds you need to look at two figures. Your Vmax in knots and in Mach. You can never exceed either one of them.
When flying at 21.000 feet you are simply not high enough to fly .77M you will exceed your maximum Airspeed in kts.
As you climb higher your M. number will increase as your kts speed stays the same: 250kts at 21000ft is around 0.5M but 250kts at 31000ft could be as high as 0.7 or 0.8M.
What you should do in your climb is to select a climb speed (280kts f.e.) until you reach a machspeed of f.e. 0.7 than continue your climb at that mach speed until you reach cruise altitude. For a CRJ typical cruise is somewhere between 30 and 35000 ft. Here you can fly at 0.77M without your wings snapping of and plunging yourself to a certain death.

Harro