aro

I'm pretty sure the responsibility is 100% on the car driver to make sure they have the appropriate license for what they are driving. But I don't see any claim like that in the ad anyway. What if a vendor claimed a 28 knot stall speed and it turned out that was IAS and the real stall speed was higher, also the claimed stall speed was at 450kg not the higher MTOW allowed in Australia?

Most of these conditions apply to an aircraft or engine type, they are not issued to a specific aircraft. The exception is 262AP which is an authorization to operate over built up areas, which is issued to a specific aircraft. I would expect that authorization to go with the aircraft if it was sold, I think it is effectively forms part of the certificate of airworthiness.

This is a good illustration of the problems calculating your own factors. The speeds need to be calculated based on Calibrated Airspeed (CAS) which is IAS corrected for errors due to the location of the pitot/static ports on the airframe. These errors are significant at low speed in a C172. Stall speed with flaps in a C172 is 48 KCAS. Without flap is 53 KCAS. So 1.3 x Vs0 is 63 KCAS. If you want to calculate a minimum maneuvering speed of 1.4 Vs1 that is 74 KCAS. Before use these need to be converted to IAS, but the errors are smaller at these speeds. 74 KCAS is about 75 KIAS. 63 KCAS is 60 KIAS. 60KIAS is the lower bound of the book approach speed (60-70 KIAS) so it works out. These are pretty slow speeds to be operating a C172, particularly at MTOW. 70-75 KIAS is probably reasonable for slow operations with 10-20 degrees of flap. If you need slower, you probably want a helicopter.

Marking the airspeed indicator in IAS seems pretty simple. There is one person who brought TAS into the thread via attempts to use the lift equation. I have a couple of comments on the original video: Adding markings to the indicator that could be mistaken at a glance for the needle seems unwise. If you're going to do it, perhaps use short markings at the edge, similar to eg. VNE. I am not convinced that the relationships between the different airspeeds (Vref, Vy etc) that he talks about always holds. I would have to do more research on that one. In particular, Vx, Vy will have different flap settings than Vref so any resemblance is likely to be coincidental.

It can't legally be flown at all unless the pilot is appropriately qualified i.e. pilot certificate. Does that need to be pointed out?

RAA registered aircraft.

There are multiple conditions that apply to the aircraft. See CAO 95.55: 7.3 A person must not operate a relevant aeroplane in Class A, C or D airspace, or an active restricted area, unless all of the following conditions are complied with: (a) the aeroplane: (i) is certificated to the design standards mentioned in Schedule 1 to the Civil Aviation Amendment Order (No. R94) 2004 (also known as section 101.55 of the Civil Aviation Orders), as in force on 31 May 2016; or (ii) meets the criteria stated in paragraph 21.024 (1) (a) or 21.026 (1) (a), or regulation 21.186, of CASR; or (iii) is approved under regulation 262AP of CAR in relation to flights over closely-settled areas; (b) the aeroplane is fitted with an engine: (i) of a type mentioned in paragraph 6.1 of Schedule 1 to the Civil Aviation Amendment Order (No. R94) 2004 (also known as section 101.55 of the Civil Aviation Orders), as in force on 31 May 2016, or of a type that CASA has approved as being suitable for use in a relevant aeroplane; and (ii) that is not subject to any conditions that would prevent the flight; (c) the aeroplane is fitted with a radio capable of two-way communication with air traffic control; (d) the aeroplane is flown by the holder of a pilot licence with an aeroplane category rating: (i) issued under Part 61 of CASR; and (ii) that allows the holder to fly inside the controlled airspace; (e) the aeroplane’s pilot has a valid flight review for the aeroplane’s class rating, under Part 61 of CASR; (f) if the controlled airspace in which the aeroplane is operating requires a transponder to be fitted to the aeroplane — the aeroplane is fitted with a transponder suitable for use in the airspace.

Let's take Vs1 for a C172 as an example, which is 48 KIAS. If you take off at Moorabbin on a 35C day and climb to 7000 feet where it is 20C, Vs1 in TAS* is initially 50 and increases to 55 as you climb. What value "could" you mark on the TAS scale? *In fact it is not really TAS because at low speeds there is significant error in the indicated values. The actual TAS values are 55 and 61. We would need a new concept, "Indicated True Airspeed".

It's irrelevant... you can pick individual elements out that are correct. It is when you put them together they make no sense.

A change in QNH doesn't generally change air density enough to significantly effect TAS. What does affect air density is temperature and altitude. There is a big difference between landing at Moorabbin on a cold winter's morning and landing at Mt Hotham on a hot summer day. At Moorabbin the density altitude might be minus 1000 feet, at Mt Hotham over 6000 feet. If your Vref is 65 knots, one is 64 knots TAS, the other is 71 knots TAS. But the characteristics of the air speed indicator mean that 65 knots IAS is correct for both. To be blunt, it is not the definitions that are the problem. The problem is that most of your explanations are misleading or incorrect. You need to revise your BAK before trying to teach other people. It is not fair to the people who are trying to learn this stuff to post so much incorrect information.

The lift equation also uses density. It's inconvenient to constantly adjust speeds for changing density, but luckily IAS for a particular TAS also changes based on density. The density components in the lift equation and IAS conversion cancel out, which means that stall speed etc. occur at the same IAS regardless of density, and we can mostly ignore TAS except when flight planning.

It's only supposed to be twisted 6-8 turns per inch, according to the manuals

The important V speeds Vs0, Vs1, VFE are IAS not TAS. Maneuvering speed is IAS but reduces with weight. The only speed that might be TAS is VNE.

It is definitely valid to decrease weight for an airport that is hot or high. GA aircraft will normally have performance charts that allow you to figure out whether you can take off or land in the space available at a specific weight. If the answer is no, one solution may be to reduce weight. The same applies to any aircraft, however it is more difficult if there are no performance charts for weight. It is still good to be aware of the problem. You can't use the same logic to increase weight because you don't know the limiting factors for MTOW.

Also the engine power is reduced (unless you have a turbo) so acceleration is reduced which increases the time it takes to get to the higher speed.

I'm not sure what you mean by "flys badly". If it truly flys badly it probably isn't a temperature thing. There are a number of factors that might influence MTOW: - Structure - how strong is the airframe? - Regulations e.g. a limit on MTOW or stall speed - Performance - the ability to climb after takeoff, or go around in landing configuration Temperature and altitude (i.e. air density) affect the true airspeed you need to fly and also the power available from the engine i.e. decreasing density has a double effect. It is possible to translate a high temperature into an equivalent lower temperature at a higher altitude. This is part of the performance subject in the PPL syllabus. It's more likely to be part of runway distance calculations than absolute MTOW though. I guess it is possible to have density limits on MTOW for climb performance, but I can't think of any examples.

I don't think coastal was specifically offered, only implied. The report says no tracking information was given, only that a clearance would be available "at or below 1000 feet". Coastal would have been 10 miles left of track, whereas 5 miles right of track would have taken him around the airspace at his 6500 cruising level. He seemed to be going right of track and around the airspace before being offered at or below 1000 feet.

He was denied a clearance, and turned right to avoid the CTA. Then he received a clearance from the Class D controller with the instruction "not above 1000 feet" and turned back on track and descended. The only problem was the ground level on track was 3000 feet.

You specifically said making a turn. A change in the mass due to fuel burn is one of the changes it is simpler to ignore. But the force resulting in THAT momentum change is drag.

The source of the force that makes the change is the wing. We bank the aircraft, which means that there is a sideways component to the lift force. This sideways force turns the aircraft.

Lets go back to the original statement and look at it in more detail: OK The laws of physics don't allow it. It's like dividing by zero in the middle of a sequence of calculations. Everything that follows is invalid. After a turn, if kinetic energy is unchanged, airspeed must still be 150kt. If momentum is unchanged you are still travelling at 150kt in the original direction while pointing 90 degrees to the original path. (In a helicopter maybe?) It is important that people understand this is wrong. Because airspeed, velocity, momentum, lift are all relative to the air, not the ground.

A turn is a change of momentum. The change of momentum is what is being analyzed. You can ignore some things e.g. kinetic energy and even gravity and get a useful answer. But not momentum.

The speed and quantity of kinetic energy do not change. Momentum definitely does change. Ignoring that is ignoring the laws of physics. The question is fundamentally about the force required to make the change - ignoring it makes no sense.

Velocity is a vector which means if you change direction, velocity and momentum have by definition changed. The force to change comes from the lift of the wings acting towards the centre of the turn.

#4 is wrong so any conclusions are invalid. Momentum has a direction. Momentum is not conserved, it is changed from one direction to another. That requires a force - the lift produced by acting on the air. Forces are acting on the air, not the ground so everything needs to be worked out relative to the air mass. The ground is irrelevant, apart from visual illusions.