Simviation Forums

Is it normal for speed to go down during ascent to cruise altitude?  In some cases it goes down very drastically and I can only get to around 15,000ft (from sea level).  Is it a problem with flight dynamics?  Anyway, the newest plane I've been having this problem with is Mike Stone's A320.  Any suggestions? Thanks!

When you're riding a bicycle, do you find that you tend to go slower uphill?

I presume you are flying the climb manually...?  Try using the autothrottle with IAS set at least 250kias

i think what he is saying is that he can only get to 15000 feet witch is a bigger problem. if you are using a throttle see if it is working right, make shoure that the aircraft that you use is made to do that and that your climb is not too steep and that the auto piolet is not a conributing factor by being set wrong or just being on

Well all of you are right  :) The whole 15,000 feet thing is the height i ususally get at before I go into a stall  :o...but anyway I'll deffinitely try the Learning Center and I'll also try to reduce my rate of climb...I had it up a little high at around 2,000-3,000fpm.  Stupid me!  :P Thanks for yor help!

I always climb out at the vs of 2300fpm in the b732 and yes the speed drops slightly, it will do as you get higher, but this is indicated air speed so it will slow down, the ground speed should be ok though. You mentioned stalling, this should not happen, sounds to me as if the payload is set too high and the plane cannot climb. Check the payload and make sure the plane is below the max takeoff weight. This should solve the problem

I always climb out at the vs of 2300fpm in the b732 and yes the speed drops slightly, it will do as you get higher, but this is indicated air speed so it will slow down, the ground speed should be ok though.

Mmmm... the GS will increase, your IAS should stay the same throughout the climb (250 below 10,000, roughly 280-290 after)  

You adjust your ascent rate to maintain your speed.  For example, if I'm climbing through FL240 at 280 kts and 2300fpm and my throttles are about to push the N2 into the red trying to maintain speed, I'll decrease my rate to +2100fpm to maintain 280kts without overstressing the engines.

YUP.. just like in a little Cessna. You've got a target airspeed and power setting for just about every phase of a flight and you pitch for that airspeed. Auto-throttles make it a little more complicated as they sneak in and chang your power setting.. but it's still the same theory.. "pitch for airspeed"

"pitch for airspeed"

In jets it's more of a "pitch for a power setting that gets you a specific airspeed" (in the 172 you're full throttle throughout the climb) but the general idea is pretty much the same, yes

In jets it's more of a "pitch for a power setting that gets you a specific airspeed" (in the 172 you're full throttle throughout the climb) but the general idea is pretty much the same, yes

Care to elaborate on that?
Just interested in what you mean, that's all.

This all brings up an interesting thought. I wonder why big jets don't have an auto-throttle that you set by power (N2 or some other reference) instead of just being able to set an airspeed (maybe they do ?).

If you you're trying to pitch for airspeed by changing the vertical-speed.. you're kind of dueling with the autopilot as it's trying to set power for airspeed.

Once cruising the airspeed is the logical thing for an auto-throttle to regulate, but during a climb, you'd think some sort of power setting would be more useful.

I suppose it's six-of-one / half-dozen-of-the-other.

I need coffee  ::)

Well Brett.
The most used climb mode in the Boeings uses a fixed N1 target, and adjusts the pitch to get the airspeed generated by either the crew or the FMC.

That makes sense.. sorta ..

So you can set the auto-throttle for N1 instead of airspeed ?  Or do you just not use the auto-throttle at all ? Or............ are you (or the FMC) constantly adusting throttle AND pitch (I can't help but picture a problem there..  two variables, each varying the airspeed) ?

Doesn't airspeed alter N1 even if the throttles have been epoxied, riveted and spot-welded  :D  to a setting ?

[quote]Doesn't airspeed alter N1 even if the throttles have been epoxied, riveted and spot-welded

Below 24000 ft most jets will be able to climb at or below 2000ft per minute with an ias of 250knts.

Above 24000 ft it is better to use mach and that depends on the aircraft.

eg. the VC10 was and still is the only passenger jet transport with an aerobatic category.  And with a VNE of .92 mach is still the fastest jet transport save Concorde.

To maintain a climb and cruise at/to say 42000 ft in this aircraft one sets the autopilot to maintain .86 mach

In the descent one progressively reduces mach until 24000 ft and then you revert to ias

The climb out speeds  ias and mach should be in the manual that came with your a/c or at least somewhere in the read me files.

Remember that a good landing  is one you walk away from!

Vololiberista