15 votes
Accepted

What is the difference between Vs and Vs1g?

User Sidestick_n_Rudder posted on PPRuNe (emphasis mine): Vs1g is the lowest speed, at which the airplane can maintain 1g, i.e. level flight. It corresponds to the Cl max Vs is the lowest speed ...
  • 6,193
12 votes
Accepted

What is the general mathematical relationship between increasing an airplane's weight and the needed thrust to fly?

While the takeoff and stall speeds increase, the cruising speed doesn't need to change. Assuming that the cruising speed is kept constant, the thrust increase can be derived as follows: At cruise, the ...
  • 4,252
10 votes

Do pitot tubes account for reduced pressure at altitude?

A pitot tube measures the ram airflow entering the pitot tube which is aligned with the direction of flight. The difference between static air pressure (from a hole usually located at a perpendicular ...
  • 20.9k
8 votes

Please describe ram pressure in simple terms

Airspeed is basically measured by measuring the kinetic energy of the air molecules impacting dynamic pressure port (for example on a pitot tube). The higher the velocity, the more energy, hence more ...
  • 21.8k
8 votes

How can an ultralight be slowed down for landing in a tailwind?

You don't change anything expect perhaps use short field landing technique to minimize your landing groundspeed, but otherwise you take the high ground speed. In light winds this isn't that big a deal ...
  • 110k
6 votes

Ground Speed vs True Airspeed from Departure Point to Destination - time interval

Computing GS takes into account the wind and how fast you are actually traveling through the air-TAS For example, if you are flying east bound through a mass of air (the "wind" refered to ...
  • 20.9k
6 votes
Accepted

Airspeed change in wind shear

Let's consider a simple example: you fly at a true airspeed (TAS) of 100 kt with a tailwind (TW) of 20 kt. This would result in a ground speed (GS) of $$ \text{GS} = \text{TAS} + \text{TW} = 100 \, \...
  • 47.6k
5 votes
Accepted

How is CAS ans GS affected by instant wind changes at different altitudes

Aircraft fly relative to the surrounding air. If your aircraft is trimmed to fly at a certain airspeed, and the airstream changes due to wind or other factors, the aircraft naturally returns to its ...
  • 1,703
5 votes

Please describe ram pressure in simple terms

Remember that an airspeed indicator is a simple differential pressure gauge. It reacts to a difference between static pressure and ram (stagnation) air pressure. Static air pressure is just the ...
5 votes

What is the general mathematical relationship between increasing an airplane's weight and the needed thrust to fly?

For the majority of planes and flights in practice, it's untrue that cruise speed increase with weight. Heavier flights would fly a higher AoA instead, maintaining the same cruise speed. Every plane ...
  • 2,495
4 votes

How can an ultralight be slowed down for landing in a tailwind?

I think this anecdote bears directly on your question-- I often shoot downwind landings in winds up to 10 mph in a lightweight radio-controlled model airplane of tailwheel configuration. The key is ...
  • 17.6k
4 votes

What equations and constants did they use to build the E6B flight computer?

The Aviation Formulary curated by Ed Williams is probably the best all-around source for the equations. His going-in assumption is that you have a working understanding of the specific concept and ...
  • 2,038
4 votes

How do test pilots verify TAS?

On the newest experimental development programs they use what are called "Smart Booms", or Smart Air Data Test Probes, for the test a/c, which is a flight data probe or boom that doesn't ...
  • 110k
4 votes

How do test pilots verify TAS?

The "Brauniger IQ Comp" variometer which is at least two or three decades old now is a rate-of-climb instrument for hang gliders. It is capable of producing a wind direction and wind speed ...
  • 17.6k
4 votes
Accepted

What is the green arrow on the 777's airspeed tape? Does it exist on other types as well?

The green arrow is the speed trend vector showing predicted airspeed in 10 seconds: 2 Speed Trend Vector Indicates predicted airspeed in ten seconds based on current acceleration or deceleration. (...
  • 47.6k
4 votes

Please describe ram pressure in simple terms

The airspeed indicator is based on ram pressure for a very good reason: because the wings need to deflect a certain mass of air in a certain amount of time to generate lift to support the aircraft. ...
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 ...
  • 17.6k
3 votes
Accepted

Do pitot tubes account for reduced pressure at altitude?

No, pitot tubes DO NOT account for reduced pressure at altitude. The indicated airspeed from the pitot tube is only equal to true airspeed at sea level on a standard day. (15C and 29.92” pressure) As ...
  • 34.4k
3 votes

What equations and constants did they use to build the E6B flight computer?

Given the era it was developed and it's Navy origin, I suspect the basis for the E6B atmosphere calculations was NACA Report 218, written by Walter S Diehl of the Bureau of Aeronautics, Navy ...
3 votes
Accepted

How can PreciseFlight speedbrakes double the drag while being so small?

Essentially, they are selling a spoiler. The way they can claim "doubling the drag" may be as follows: The device spoils lift, thereby reducing lift cofficient. This results in the aircraft ...
3 votes

If the altitude of the aircraft is given by the pitot tube, in icing condition with heat on, how is real altitude /speed interpretation done?

The pitot tube measures pressure, not density. The pressure is not affected by the heating of the tube.
  • 75.4k
3 votes

Ground Speed vs True Airspeed from Departure Point to Destination - time interval

How does GS determine the time interval it takes for an aircraft to fly from the DP to the DEST, if TAS determines how the fast the aircraft is really going through the air. The simple answer to this ...
  • 68k
3 votes

Does Indicated Stall speed increase with altitude (Coffin Corner)?

I think part of your confusion comes from mis-interpretation of the amber bands on the PFD. The picture you show looks like it is from a Boeing 777, which has the red barber pole and the amber band ...
  • 47.6k
2 votes

How does supercruise thrust compare with static thrust ASL?

According to the wiki page of the Rolls Royce/Snecma Olympus for the Concorde: During cruise at Mach 2.02 each Olympus 593 was producing around 10,000 lbf of thrust... Eames (SAE Transactions 1991) ...
  • 58.9k
2 votes

Power calculation of propeller

The equation Thrust * Airspeed / (Torque * AngularVelocity) is indeed the correct one for propeller efficiency, implying that we get an efficiency of zero at take-off. For aeroplane propellers there ...
  • 58.9k
2 votes
Accepted

How to compute the airspeed change based on the Altitude change

At the most basic level the Mach formula is: Mach = TAS/Speed of Sound The speed of sound is a slightly non-linear function of temperature: ...
  • 2,038
2 votes
Accepted

TAS from POH or e6b

Using the POH with a fixed power setting is more correct, and as a student, you should absolutely do it that way. The POH is where you get your fuel burn per hour. That, combined with GS and ETE per ...
  • 26.7k
2 votes

Please describe ram pressure in simple terms

Ram air pressure is simply the airflow pushing against an object. Imagine travelling down the freeway at 75 MPH. You open the window and stick out your hand. That pressure is ram air pressure. The ...
  • 11k

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