14 votes

Why don't Transport Category aircraft have a listed Vy?

Large commercial jets operate within a much wider range of weights than most GA aircraft do, and since Vy varies with weight, it wouldn't make sense to publish "a" single Vy speed for them. The crew ...
Ralph J's user avatar
  • 50.6k
12 votes

Is Vertical Speed based on True Airspeed or Groundspeed?

Vertical speed, as measured by the Vertical Speed Indicator (VSI) should be measured entirely by the changing air-pressure at the static port, and should be completely unrelated to airspeed and ground ...
abelenky's user avatar
  • 30.7k
12 votes
Accepted

How does a nose down stall occur?

Does normal laws apply when the aircraft nose is vertically down? Yes, always. Physics doesn't care much about the aircraft's attitude and cannot be switched into different modes. While the nose ...
Peter Kämpf's user avatar
9 votes
Accepted

What are the consequences of touching down at too low of a speed?

This is certainly not a comprehensive answer but can get you started. I’m assuming fixed wing non-VTOL aircraft. A low (forward) speed touchdown, all other things being as close to nominal as ...
Cpt Reynolds's user avatar
  • 4,797
8 votes

What is the descent rate in emergency situations?

In a rapid depressurization, you'd typically descend at MMO and transition to VMO until reaching your level-off altitude. This is accomplished with the speedbrakes extended. What vertical speed you'd ...
Ralph J's user avatar
  • 50.6k
5 votes

How does a nose down stall occur?

Absolutely. Stalls occur when the critical angle of attack is exceeded, plain and simple. While it's easy to see this when the aircrafts nose is really high above the horizon it can actually occur at ...
Greg's user avatar
  • 51
5 votes

What is the descent rate in emergency situations?

The Mesa E175 that had an emergency descent about a year ago peaked around 7000 fpm, in total taking 6 minutes to descend from FL340 to 10,000 ft. (flightaware.com) In light of the comments above ...
Mark's user avatar
  • 61
5 votes

What is the descent rate in emergency situations?

I can't answer for to 40,000 feet (FL400—Flight Level 400—in pilot parlance), nor to an A320 or B737. I can answer for a piston engine airplane with retractable landing gear at FL250, though. As a ...
ammPilot's user avatar
  • 516
5 votes

Is there any practical benefit of the Boeing-787 to perform near vertical takeoff?

The 787 was not designed to perform such a maneuver. Any jet airliner could do this. What you need for such a steep climb is a good thrust to weight ratio (or enough excess speed to bleed off during ...
Bianfable's user avatar
  • 55.4k
5 votes
Accepted

What is the vertical speed limit when altitude mode is engaged?

What you are describing is the managed climb mode of the Airbus, where the Flight Management Computer (FMC) determines the optimum climb speed and the autoflight system will then pitch to maintain ...
Bianfable's user avatar
  • 55.4k
5 votes

Trying to find the vertical acceleration by subtracting weight from lift

Your math looks right to me. If an airplane has the statistics that you listed there, then it will accelerate upwards at $16.48\ \mathrm{m}/\mathrm{s}^2$, as you calculated. The occupants will ...
Tanner Swett's user avatar
  • 5,771
4 votes

Is it possible to see the same sunset twice from an aircraft?

Concorde did something similar: it would take off from London at sunset and then fly West faster than the Earth's rotation, so you would get a sunrise in the West on board. This capability was also ...
Hobbes's user avatar
  • 10.2k
4 votes

Is there any practical benefit of the Boeing-787 to perform near vertical takeoff?

The 787 (and other commercial aircraft) are built to carry large loads, whether lots of cargo, or lots of passengers and bags. So, when empty, their performance is much better. If it can do a normal ...
abelenky's user avatar
  • 30.7k
4 votes

How is a "turning polar" constructed?

It looks to me that, to draw each small polar (for 20°, 30°, 40°, 50°, 60° bank), the bank angle is fixed and all possible pitch angles are "flown"; the resulting turn radius and sinking ...
quiet flyer's user avatar
  • 22.2k
3 votes

Airbus 320 VS mode

In speed mode, the autothrust varies engine thrust to maintain the pilot selected or the FMGC (Flight management guidance computer) calculated speed. In V/S mode, the priority is the selected vertical ...
Anas Maaz's user avatar
  • 1,943
3 votes

Is there a way to calculate the difference in pitch required to reach a certain vertical speed?

I'm surprised no-one has attempted to answer this question, as it is mostly a pilot's daily job to guess a pitch change that would give a certain rate of climb. :-) This will not be a technical ...
Radu094's user avatar
  • 7,925
3 votes

Why are the altitudes and distances in the profile view different when calculated with the fpm values in the conversion table on Jeppesen charts?

So, I decided to just start from scratch and build a model that started at the TDZ and worked back out. I wanted to determine what would happen if the DME antenna was not precisely collocated with ...
Max R's user avatar
  • 3,780
2 votes
Accepted

What is the name of centre of mass speed of an aircraft?

It describes what the velocity vector of the aircraft centre of gravity is in relation to the surface of the earth. Ground speed is the 2-D projection of your speed on the ground, climb speed is the ...
Koyovis's user avatar
  • 61.6k
2 votes
Accepted

Is this scheme for a single-fan electric airship with a rocket-like geometry workable?

First, you need thrust-to-weight¹ ratio more than 1, so the device can maintain flight. You should be able to find data about how much thrust (lift in case of rotors; it's the same thing) they can ...
Jan Hudec's user avatar
  • 56.2k
2 votes

Is this scheme for a single-fan electric airship with a rocket-like geometry workable?

The best propeller driven vertical take-off and landing craft would be a helicopter, actually. Yes a duct around a propeller increases thrust, but upsizing a propeller creates way more thrust from the ...
Koyovis's user avatar
  • 61.6k
2 votes

Why don't Transport Category aircraft have a listed Vy?

Well they do of sorts. But your pilot friend is right, they are not tabulated for a transport category aircraft like is done for a Part 23 aircraft. Due to the large payloads, CG ranges and ...
Romeo_4808N's user avatar
  • 73.5k
2 votes

What’s the speed for lowest sink rate on a DA20?

Admittedly, my prop performance theory is a tad rusty, so maybe someone else can provide proof here. I seem to recall that - assuming a quadratic drag polar which might not hold true for your ...
Cpt Reynolds's user avatar
  • 4,797
2 votes

Is it possible to see the same sunset twice from an aircraft?

This question has merit in that it touches on weather and the earths rotation, which are certainly aviation related. Amazingly, at the equator, the earth rotates at around 1000 mph, with the ...
Robert DiGiovanni's user avatar
2 votes
Accepted

How is a "turning polar" constructed?

I think it's much more intuitive to draw this "turn polar" in terms of airspeed instead of turn radius. Note that bank angle directly relates to centripetal acceleration, which together with ...
Sanchises's user avatar
  • 12.9k
1 vote

What is the vertical speed limit when altitude mode is engaged?

The situation behind your question, "the aircraft is flying towards a target altitude and the pilots want to limit the vertical speed for any reason," would arise when an aircraft is ...
skipper44's user avatar
  • 1,605
1 vote

Trying to find the vertical acceleration by subtracting weight from lift

I would say what the original question describes is something like the start of a loop. The pilot's elevator controI input that creates the 1.5 CL (about 3G in this case) condition also initiates a ...
quiet flyer's user avatar
  • 22.2k
1 vote

Is it possible to see the same sunset twice from an aircraft?

“Is it possible to see the same sunset twice, from the same aircraft”. Well, it is possible, to see two sunrise’s on the same flight, although these are not the same sunrise’s: See: Chasing the ...
Penguin's user avatar
  • 4,493

Only top scored, non community-wiki answers of a minimum length are eligible