aro
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Everything posted by aro
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You attack and insult people who disagree with you, but will only stand behind your posts with angry words. Never mind, my offer still stands. If you find someone with a degree in physics or aeronautical engineering who will publicly say you are more correct in the instances where I have disagreed, not only can you point to it and say I was wrong but you will earn $500 for your favorite charity. That is how confident I am in my information - I will put up $500 to zero to back it. (I have taken a copy of the thread for the purposes of the offer, in case moderators decide to moderate.)
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I am becoming more confident I was right earlier: All I can say is that if you want to rely on OME's posts for exams etc, get a second opinion from someone qualified first. In fact that's not a bad idea - how about a challenge? If someone can find a person with a degree in Aerospace or Aeronautical Engineering or Physics who is prepared to be publicly identified and say that based on their knowledge and qualifications, OME is more correct than I am where I have disagreed with him here, I will donate $500 to a charity of their choice. OME: how confident are you about your posts? Are you prepared to take the opposite side?
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Inertial isn't a force, and using pseudo forces or fictional forces to try to define inertia is not helpful.
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Inertia isn't a calculated value. Also from that reference: Mass is a measure of an object's inertia. Inertia has to do with mass alone.
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By that argument my car follows a ballistic trajectory when I drive over the Westgate Bridge, if you ignore the influence of the road surface holding it up. It makes no sense to ignore the lift from the wings.
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You asked for a reference, but did you actually read it? You are rejecting the definitions from physics and substituting your own.
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The flight path is so different from a ballistic trajectory that it is unreasonable to describe it as ballistic, no matter what riders you apply. It's the difference between an aircraft and a cannonball. See Q1 answers c, d, e, f, g, i here: https://www.physicsclassroom.com/reviews/Newtons-Laws/Newtons-Laws-Review-Answers-1 Mass is a measure of an object's inertia. Any object with mass has inertia. Mass is a measure of an object's inertia. Objects with greater mass have a greater inertia; objects with less mass have less inertia. The speed of an object has no impact upon the amount of inertia that it has. Inertia has to do with mass alone. Inertia (or mass) has nothing to do with gravity or lack of gravity. In a location where g is close to 0 m/s/s, an object loses its weight. Yet it still maintains the same amount of inertia as usual. inertia is unaffected by alterations in the gravitational environment. An alteration in the g value effects the weight of an object but not the mass or inertia of the object.
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It's not nitpicking to point out that aeroplanes have wings and as a result the trajectory is nothing like ballistic - even when stalled. Some aircraft have lost their wings in flight - they will follow a ballistic trajectory. You might think the difference between aircraft with and without wings is a nitpick, I do not. Physics of flight are not as simple as you seem to think. I said relative to the aircraft. In a climb, the centre of the planet is towards the rear of the aircraft - and gravity slows you down. In a descent, the planet and gravity is towards the front, and causes you to speed up. In a 30 degree banked turn it is out to the side. The gravity vector moves around relative to the aircraft. This is fundamentally wrong. An object with mass does not have zero inertia. Mass (kg) can be described as a measurement of inertia. If you push your car and it is hard to get it moving, that is inertia. As you keep pushing, it gains momentum. When you stop pushing and it keeps moving that is inertia. When it hits the car in front and they end up travelling locked together at 1/2 the speed, that is momentum. Momentum is a quantity that can change and be transferred from one object to another. Inertia does not change.
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Two things are glaringly missing: Physics, and aerodynamics past PPL level. I don't see any more qualifications than many other posters to the site. The traffic accident reconstruction is interesting, it maybe explains some of the errors e.g. the reference to ballistic trajectories. A car that leaves the ground in an accident will follow a ballistic trajectory. A ballistic trajectory in an aircraft is unusual e.g. the Vomit Comet, some aerobatics perhaps, or floating dog videos. A stalled aircraft will not follow a ballistic trajectory. Nor will an aircraft when you reduce power. Most of OME's errors are year 11 physics and BAK level stuff. Your Dynon, Garmin etc. EFIS has all that information. They can't use it to generate AOA information. They require additional information e.g. pressure sensors at an angle to the airflow for AOA. More advanced systems use a vane on the outside of the aircraft, i.e. direct reading of AOA.
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OK... lets say we climb an aircraft at 60 knots with an angle of climb of 5 degrees. Then we reduce power to descend at an angle of 5 degrees at the same 60 knots. The airspeed is the same. The angle of attack must therefore be the same. What do you expect your indicator to show? I would expect it to show a change of 10 degrees, where the correct indication would be a change of zero.
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There's the problem. It won't work in a descent, which is an important part of circuit work. If the reading is totally different in a climb and in a descent at the same AOA, it is not an AOA indicator. You need to measure AOA in relation to the aircraft. But the spirit level reading is influenced by both gravity and the acceleration of the aircraft. Gravity moves around relative to the aircraft as the attitude changes. A spirit level is in principle the same mechanism as your inner ear. We know that the inner ear is unreliable and subject to illusions due to acceleration etc. Your proposed AOA indicator suffers the same problems.
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Because that is the most efficient angle of attack for cruise flight. Straight and level is not an angle of attack. The point is climbing and descending is not a result of more or less left. When climbing, lift is less than in straight and level flight. It will descend. It is hopefully not a ballistic trajectory. The actual behaviour is typically adjusted by modifying the thrust line of the engine in the design/testing phase. Climb comes from excess power. Best climb speed is maximum excess power. Descent comes from insufficient power. So your aerodynamics is basically PPL? Why do you think that prevents people questioning your information?
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I would say it's about 95% standard mechanics, 5% major errors or misunderstandings. An example from the previously linked Social Australia post (where we can't comment) : In fact, inertia is mass. An object has the same inertia with or without gravity. Assuming the force is lifting the object against gravity (it is not centripetal force unless the object is travelling in a circle), the object will move when the tension exceeds the force of gravity. How fast it accelerates depends on the inertia (mass) of the object and how much the tension exceeds the force of gravity, i.e. the net force.
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A "straight and level angle of attack" is an example of something that doesn't actually exist. With enough power you can fly straight and level at any angle of attack from VNE through to stall speed. I'm not sure that your understanding of angle of attack is correct. What do you think the angle of attack will be at 60 knots cruise? 60 knots climb? 60 knots glide? Pulling 4G at 120 knots 3/4 of the way around a loop? All will be the same angle of attack. What do you think your bubble AOA indicator will show? Descent doesn't mean lift is insufficient. Lift doesn't change significantly in a climb, descent or straight and level. (Ignoring the vertical components of thrust and drag, which actually reduce lift required for both climb and descent). Climb and descent are a result of power settings. Descent means that you have insufficient power to overcome drag, climb means you have more power than drag. They are not an increase or decrease in lift.
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That's the point I think. APenNameAndThatA was listing things that OME has posted that are not actually true. I'm sorry if OME feels picked on. What do you suggest should be done when incorrect information is posted to the Student Pilot area? I have a growing suspicion that OME is trolling us with deliberately false theories. If so the joke is on us I guess. But it is a bit unfair to student pilots who might be trying to learn this stuff, and unfair to the owner of the site who is trying to create a useful resource.
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If there are major errors (which there are in many of your posts) pointing out the errors should be enough. But as with most things, it is slower to correct errors than to make them. What qualifications do you have that you come and give "lectures" and call people who disagree hecklers?
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See the F104: https://en.wikipedia.org/wiki/Lockheed_F-104_Starfighter Also from the Wikipedia article: the aircraft designers developed a boundary layer control system, or BLCS, of high-pressure bleed air, which was blown over the trailing-edge flaps to lower landing speeds by more than 30 knots
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I don't think that was the best L/D, also I'm not sure that 2d numbers are comparable to real numbers for a 3d wing. It's not very surprising that a very thin wing works well at high speed with less drag than a thick wing. It would have been more interesting to increase AOA to recover the lift and see what happens, rather than increase speed.
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I don't know... I think the biggest problem converting to tailwheel is unlearning bad habits from tricycle. The #1 bad habit is relaxing when the main wheels touch down. I flew tailwheel before first solo, and at that point you really don't know any difference. You do a lot more circuits when learning than during an endorsement, and the biggest difference is that with a tailwheel you have to work harder in the seconds after touching down. That is just dead time in a tricycle. The tailwheel aircraft gives feedback on your landing every time, better than the instructor in a tricycle.
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That sounds a bit like the aircraft I flew with the tight tailwheel - it was very hard to get it to turn. Although with a tailwheel you do often need opposite rudder through the turn to stop it tightening up - it is not a case of rudder to start the turn, opposite rudder to stop it. It's rudder all the time.
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As has been pointed out taildraggers are directionally unstable, but this is at medium speeds and above. At low e.g. walking speed they can actually be more stable due to the distance between the tailwheel and main gear. However... they typically have chains and springs between the rudder and tailwheel. Some aircraft have these very loose, some tighter so they will have different steering response through the tailwheel. I can imagine with the loose ones the tailwheel steering might feel vague - although the looseness might be necessary so it isn't too sensitive at higher speeds. One of the aircraft I did my endorsement in was a Decathlon where the tailwheel was done up so tight it would barely respond to the rudder pedals (I suspect to stop shimmy). It was bad enough the instructor had helpful advice like sometimes to turn downwind you need to do a 270 degree turn in the opposite direction due to weathercocking. At the end of a lesson my legs were worn out and shaking from pressing the rudder pedals to try to get it to turn while taxying (in hindsight I think I was just pressing on the rudder stops). It was a revelation when I went elsewhere and flew a Decathlon where the tailwheel was loose enough to steer...
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That's a pretty black and white statement. It's either true or it's not. If the pilot doesn't have the qualifications it's nothing to do with the aircraft.
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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?
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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.
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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.
