Jump to content

aro

Members
 View Profile  See their activity

  • Posts

    964

  • Joined

  • Last visited

  • Days Won

    9

 Content Type 

Everything posted by aro

  1. aro
    A 72kWH battery will run a 90kW motor for less than 1 hour. Reduce to 50% power and you can probably claim 1 hour plus reserve. How long will 100kg of avgas run a 120HP engine at 50% power? That's the problem...
  2. aro
    That just means I found enough references to convince me, but not something to quote as a primary source. But the FAA has it: https://www.faa.gov/sites/faa.gov/files/13_phak_ch11.pdf (p 11-8): The service ceiling is the altitude at which the aircraft is unable to climb at a rate greater than 100 feet per minute (fpm). If you're familiar with Cessna 172 performance, 500fpm is obviously wrong. That would give a service ceiling somewhere around 5000'. The actual service ceiling is given as 13500.
  3. aro
    I think that number is for jets. For other aircraft the number is usually 100 fpm I believe.
  4. aro
    Yes, but "level flight" requires AOA changes as the power changes. So yes, the speed changes if you change the AOA to maintain level flight as the power changes. You are talking the practical technique rather than aerodynamics, and you are correct UNLESS you actually want to argue whether AOA or power controls the speed.
  5. aro
    You might disagree, but physics says you can't fly at a different speed at constant G without changing AOA. "Stick forces" are an indication of changing AOA. At cruise it might only be fractions of a degree and too small to call a pitch change, but the AOA is changing. Power is only a measure of energy input. If the AOA stays the same, power causes you to climb. If you change the AOA i.e. with nose down stick force to prevent the climb, speed increases.
  6. aro
    That's technique (how you do it) rather than a description of the effect. The increase in stick forces as you are accelerating is the adjustment to the angle of attack to increase speed rather than climb. When you trim doesn't change what is actually happening.
  7. aro
    The carburettor creates the temperature drop. The drop in pressure across a closed throttle plus the evaporation of the fuel significantly drops the temperature of the air downstream of the carb - by as much as 10, 20 maybe even 30C. So downstream of the carb you have water condensing out of the air, and possibly surface temperatures below freezing. So all you need is moisture in the air (humidity, not visible moisture) - the carb does the rest. https://www.casa.gov.au/sites/default/files/2022-10/carburettor-icing-probability-chart.pdf
  8. aro
    Speed is always controlled by angle of attack (at constant G). Power does not appear in the lift equation. But sometimes e.g. on a precision glide path it is easier to change power first, and then change the AOA gradually to change the speed. This avoids significant changes in flight path. The problem, and what makes this more difficult, is that changing speed also changes drag and therefor power required. So you might need more power adjustments as the speed changes. If you don't have to follow a precision glide path it is easier to set the speed first and then adjust the power. If the speed is not fluctuating, the power required to overcome drag stays the same so you don't end up chasing it. This is more pronounced at slower i.e. landing speeds. In cruise, you set the power and then adjust the trim i.e. angle of attack to give a speed where you are not climbing or descending.
  9. aro
    There's pretty much always moisture in the air in Australia. That's what appears on the outside of a cold drink. If it gets very cold the amount of moisture in the air is significantly reduced.
  10. aro
    No. I wouldn't discourage people from insuring and I applaud your intentions, but that's not what insurance is there for. Public liability insurance is there to protect YOUR assets. The insurance company takes over defending the case. If at all possible, they will pay zero to the injured party. If a payment seems inevitable, they will work to pay them the minimum possible amount. When you took out the policy, you entered a contract to help them pay as little as possible to anyone injured. It doesn't matter who they are or how badly they are injured, you must work with the insurance company to minimize their payout. If they can't show that you were negligent, they get nothing, no matter what they actually need. This isn't a very fair system - many people need help and don't get it, and much of the money is absorbed by insurance companies and lawyers. That's why we have a different system for car crashes - they are common enough that the system couldn't cope with the cases to try to prove negligence, and the majority of people who need help would miss out. So we have a no-fault system where you are automatically covered and you don't have to prove someone (with assets) was negligent.
  11. aro
    It's not exactly news that cars and trucks can be used for terrorist attacks. People have been doing it literally as long as I can remember. Wait till you find out about fiction books. 600+ pages on the details of planning new and inventive attacks...
  12. aro
    Wasn't that the thinking behind the Tomahawk? Flying schools said we want a trainer we can teach spins in, so Piper built one. Then the schools said "Oh! If you stall it it can spin, we don't like that" and didn't buy it.
  13. aro
    The problem with the ASIC is that they couldn't actually deny one to a suspected terrorist without tipping them off that they were being monitored. That would provide a tool they could use to work out which of their members was under suspicion. So more than likely an ASIC would be approved anyway for someone known to be plotting something. A security check where you voluntarily apply and get told the result is fatally compromised for any situation involving secret intelligence. Far more useful are security checks that you don't know are being done and won't find out the results (and I'm sure they occur).
  14. aro
    They don't, and you can't just fly them to another country like you could with a normal aircraft. Same applies to the USA AFAIK, the design standards quoted above do not apply to experimental category aircraft.
  15. aro
    No-one is talking about RAA getting IFR. IFR and CTA are totally different things.
  16. aro
    No-one's saying you don't need training. But you have the same deal with GA pilots flying out of controlled airports into a CTAF. Weird radio calls, no idea how to join a circuit, flying a straight in approach because that is what they would be given by ATC from that position never mind the traffic, downwind landing because there's no ATIS and the wind didn't match the forecast... all sorts of things. The idea that GA pilots fly to a higher standard is just nonsense, based on my observations. GA pilots can be just as rubbish as RAA.
  17. aro
    Austers into Mascot and DC4s are a long time ago. I did my PPL at Essendon so I know a little bit. When was the last time you flew VFR in Class C?
  18. aro
    I think people hugely overstate the difficulty of CTA. Maybe you only flew IFR in CTA? VFR is not the same as IFR. Really, the main thing you need to be able to do are: Fly a heading Fly an altitude Visually navigate and follow a track Talk on the radio and follow instructions. If you make a mistake, ATC are there to help. Will you get in the way of a jet if you make a mistake? No - ATC will keep you well out of their way so that is not possible. If you want to cause problems for jet traffic it is much more likely OCTA under the steps north or south of Melbourne - where the separation from jet traffic could be only 500' vertically - at least theoretically. Or somewhere like Mildura where you have RPT traffic in a normal CTAF. Talk to the people who fly out of Essendon and they will tell you flying into a class G airport is much more difficult because you have to arrange and judge your own separation, without ATC to help you. They hate it.
  19. aro
    Looking at the descriptions, I can't see how it could happen unless the guide track itself wasn't attached to the door properly. It will be interesting to see what they find from examining the door...
  20. aro
    See the video above from about the 7 minute mark. Are they the bolts you are referring to?
  21. aro
    But why would it bend? You would need to lift the door to bend the bolt, and you're working against gravity, landing loads (i.e. positive G) etc. It is a larger version of a cotter pin, i.e. preventing movement but not taking the load.
  22. aro
    The small bolt isn't carrying weight. It is acting as a pin to prevent the door from being lifted. The bolt is going through the piece attached to the door.
  23. aro
    If you know what you are talking about you wouldn't be asking about measuring coolant exit temperature on a suffix-01 engine. You asked: You listed CHT max as 150C. That's the CHT max for 80hp not 100, but its even more wrong if you want to call coolant temperature CHT - it should be 120C. Then you talk about measuring radiator exit temperature with a max of 120C which would be way too high. "The problem is..." There is no problem - just confusion about which numbers to use - largely, it seems because you are calling the coolant temperature measurement CHT and then applying the actual CHT limits instead of coolant temperature limits. Then you start calling people who give you the correct numbers pedants...
  24. aro
    You can simply look at the markings on the gauge, but but some people do believe that its worthwhile to learn the limits as well. This means that you need to know whether the gauge is reading CHT or coolant temperature because the numbers are different. You have confused yourself here by referring to the coolant temperature as CHT. Rotax want you to have a coolant temperature gauge. If the coolant temperature is measured in the head, you do not need a second measurement - that is your coolant temperature. If the head sensor is measuring CHT (i.e. metal temperature) Rotax want a sensor in the coolant exit to measure coolant temperature. It's all in the manuals, but you do need to track fairly carefully which engine variation each section in the manual is referring to.
  25. aro
    That pretty clearly says "Coolant temperature" not cylinder head temperature. The cylinder head is where it's measured, not the temperature being measured. In all the Rotax documentation they are very careful to distinguish between coolant temperature and cylinder head temperature. By who's convention? People who don't know any better? The numbers are different, so it is actually important to know whether your measurement is coolant temperature or cylinder head temperature. If your coolant temperature is marked as CHT, it's wrong.
×
×
  • Create New...