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aro

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About aro

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  • Aircraft
    C172
  • Location
    Melbourne
  • Country
    Australia

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  1. There was a startup called Better Place trying to build a network of battery swap stations for EVs. It relied on standardized batteries accessible from under the car. In order to access the battery switch station, Better Place customers would have to swipe their membership card. The remaining process was fully automated, similar to going through a car wash, so the driver never had to leave the car The car owner wouldn't own the batteries, they just purchased the electricity. So all the problems with battery degradation etc. would be managed by Better Place across their
  2. A reasonable estimate is that a single pump can deliver enough fuel in 1 hour across multiple vehicles to drive 5000 km in total. How much power do you need to provide enough electricity in 1 hour to drive 5000 km?
  3. I don't mean operating continuously. Check my math: My car can do about 800 highway km on a tank. Lets say you can fill 1 car every 10 minutes, that's 4800 km, call it 5000 km worth of energy dispensed per hour. A Tesla supposedly uses approximately 20 kw/h per 100km so 5000 / 100 * 20 = 1000 KWh or 1 MWh per hour = 1 MW equivalent. I think I estimated 10 cars/hour and a more efficient car when I did the original calculation, but that is the order of magnitude. I was prompted to think about it when we passed service stations on the Hume at Easter with queues
  4. Are there any models without regenerative braking? Regenerative braking is the hybrid's main advantage - all the energy comes from the ICE engine, but regenerative braking allows them to capture much of the energy normal cars lose as heat in the brakes. My point was that the hybrid is probably worst case cost and complexity wise. You have ICE, transmission, fuel system, cooling system, plus electric motor and battery. And it's still only 2K over the ICE only model. There are a surprising number of Tesla's getting around these days. I know someone who regularly
  5. Yes, looks like fun for local flying. The biggest problem if you have limited energy is drag, so I think anything practical to go further will look more like a motor glider i.e. very streamlined with a big wingspan to minimize induced drag. Pipistrel seem to be going that route, their electric aircraft are interesting. If they put their electric powerplant in their Sinus airframe it seems like it would be one of the most practical electric options.
  6. I think Tesla and Toyota at opposite ends of the spectrum show that many EV problems are largely solved. Tesla has range, fast charging and power (see ludicrous mode). Toyota put a battery, electric motor, regenerative braking etc into their hybrid models and only charge a couple of thousand extra on top of the petrol model. If Toyota want to build a full electric car they need a bigger battery and electric motor, but the cost of that should be more than made up by being able to delete the ICE, fuel & exhaust systems, most of the transmission etc. The re
  7. I don't think anyone is arguing with the idea that they refer to different things - rather that it's so obvious it goes without saying. The argument is whether something with a mass of 1 kg weighs anything other than 1 kg, when "weigh" is used in it's everyday usage i.e. stationary on the surface of the earth, ignoring local variations in gravitational force, and using kg to refer to kg-weight. From Wikipedia: The kilogram was originally defined in 1795 as the mass of one litre of water. This was a simple definition, but difficult to use in practice. By the latest
  8. You just defined force yourself, with the qualifier "when unopposed". "When unopposed" is the important bit. F = m.a BUT F is the vector sum of all forces acting on the mass. We can only calculate a force using F= m.a if there is only one force, or all other forces are known. It is very common e.g. for there to be 2 forces perfectly opposed, and therefore acceleration is zero, net force is zero, but significant and measurable force is being applied. An example is standing on a set of scales. The scales measure a force, but there is no change in vel
  9. We do not agree. That is an equation about acceleration. You can have a force where acceleration is zero. If you push a box of bricks across the floor at a constant speed, you are exerting a force to overcome friction. You can measure the work done as force x the distance you moved the box. Acceleration (once the box is moving at a constant speed) is zero, but you have a force that must be used if you want to calculate e.g. work and power. Likewise, when an aircraft is straight and level at a constant speed (i.e. no acceleration) we do not say that there is no force act
  10. That diagram is a turn not a roll. The force vectors are totally different. Nor is is a diagram of the result where the AOA remains unchanged.
  11. This video shows some interesting instruction on rolls: The whole video is worth watching, but there is discussion on the slow roll at 17:18 and hesitation rolls at 24:30. The description of the hesitation roll is that it is the same as the slow roll, but with the hesitation added. This really dispels the idea that the pilot rolls the aircraft and then corrects the flight path. It is simultaneous aileron, elevator and rudder inputs.
  12. I said lift required was infinite for a turn with 90 degrees of bank. Of course you are right. Lift required trends to infinity as you approach 90 degrees, but at 90 degrees you need to divide by zero: infinity is not the answer, there is no valid answer.
  13. Maybe if you post the answers instead we will have more luck trying to work out the question you want to ask. You introduced the question with a video, that suggests that you are intending to post a question that relates to real aircraft behaviour. Incidentally, the video includes real time G readings which actually show us the lift the wing is producing at each point. Not surprisingly they differ from the "perfect" roll I described. There are limits to how perfectly a pilot can fly, and also limits to what an aircraft is capable of.
  14. That is true if the aircraft is instantaneously rotated around an axis perfectly aligned with the airflow. But it's not real life. In real life, even at maximum roll rate it takes time to go from 0 to 45 degrees. It also depends on the skill of the pilot, but lets assume the pilot can fly the roll perfectly. As the pilot begins the roll the lift vector is pointed to the side, which would begin to turn the aircraft. To prevent the turn, opposite rudder is required and the aircraft is in uncoordinated flight. At 45 degrees, the wing provides half the lift, and the side fo
  15. An AOA indicator that according to the expert you quote "can’t tell AoA" doesn't work.
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