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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. aro

    912 Uls

    If you want to disagree with something, perhaps you can tell us what? Knowledge isn't worth much if you don't put it out there to test.
  2. aro

    912 Uls

    The shaded area is above 27" manifold pressure. Manifold pressure is reduced when you close the throttle. The reference to 3500 feet is because the air pressure reduces as you climb, so the manifold pressure possible at full throttle reduces. It is absolutely permitted to close the throttle and reduce RPM and cruise at a lower power setting because your manifold pressure is reduced by closing the throttle. The relationship between manifold pressure and rpm is set by the propeller. If you have a constant speed propeller, you have to manage manifold pressure to make sure
  3. aro

    912 Uls

    It doesn't show that at all. It has e.g. settings for 55% power cruising. What it shows is that 5200-5500 are the recommended/required rpm for full throttle at low altitude.
  4. aro

    912 Uls

    Can you provide a reference to the recommendations in the manual? I can't find anything. I have heard for many years that the 912 should be run at over 5000 rpm but I have never seen anything official from Rotax. It seems as likely as not to just be folklore. Exactly what problems are people anticipating running < 5000 rpm (assuming unleaded fuel)? Is there any real decrease in engine life?
  5. You didn't use 55l/sec in your original calculation. You used 5.5l/sec. True, but it gives a reasonable point to start from. If you really want a more accurate answer you can start refining various figures but there's probably lots of factors unaccounted.
  6. I think that is too low - should it be 55l/sec? ~40C doesn't sound unreasonable, that would presumably be measured as a drop in EGT.
  7. Cars have a knock sensor that will retard timing if detonation is detected. If they have to retard timing from the optimum value due to low octane fuel, higher octane will give better economy. If they can run at the optimum timing on the lower octane fuel (i.e. engine design) they get no benefit from higher octane. Also, some of the 98 octane fuels claim to be "denser" i.e they need a leaner mixture. A car with an O2 sensor will adjust the mixture and use less fuel. If you have a mixture control in your aircraft, you might also use slightly less fuel. A car
  8. Before V1 you need to be able to abort the takeoff and stop safely in the remaining runway. After rotation the task is fundamentally different, so V1 cannot be higher than Vr. If you don't plan to rotate at "Vr" it is not Vr. I was thinking about when V1 might apply in a single. There are problems where the correct thing to do is continue the takeoff so you could say V1 does apply. For example, if a door pops open in the takeoff roll. Early in the takeoff roll, if a door pops open, cut the power and come to a stop, no problem. If the door pops open as you
  9. The point of V1 is that it is a pre-made decision about when you will continue the takeoff instead of stopping in the event of an emergency e.g. engine failure. It is there so you don't use up runway and options while you wonder should I stay or should I go? We don't use V1 in smaller aircraft For the case of an engine failure in a single, V1 doesn't exist. Jets etc. are required to be able to stop on the runway from V1, because running off the end of the runway after an engine failure is considered a bad thing. For smaller aircraft, people don't really care e.g. your takeoff chart
  10. That's never supposed to happen. The theory is you detect the problem before V1. At V1, you should be able to reach Vr and fly away even if you lose an engine. This is factored into the aircraft design. If you need to be able to stop from Vr you potentially need a much longer runway or much more restrictive limits on weight.
  11. If you don't rotate at Vr, it's not Vr?? V1 is only applicable to multi engine aircraft. It's the point after which you can't reject the takeoff, either because there is not enough runway to stop or you have already begun to rotate. Performance calculations ensure that at V1 you have enough power to continue the takeoff even if you lose an engine. If you don't, you have to adjust performance e.g. reduce the aircraft weight. The ability to continue the takeoff or stop on the runway after engine failure is only a requirement for larger aircraft. For smaller tw
  12. Rejecting a takeoff after rotation would be considered a different kind of emergency... it gets significantly more difficult.
  13. FAR part 103 is totally different to anything we have here. It is for single occupant, <254 pounds empty, <5 gal fuel capacity, 55 knots max speed and 24 knots stall speed. As I understand it, no license or training is required. It is probably closest to the pre-AUF ultralights in Australia. Not really what anyone is talking about.
  14. Can you be specific? You quoted an EO to put a GoPro on a wing strut, whereas in the US it's a '337 Canada has 'owner-maintenance' for a range of basic GA certified aircraft right up to 172 variants Consider that you can go straight over the top of LAX, JFK or SFO in Class E in the US were you referring to any of those? Or anything specific in the post you quoted?
  15. Which "things" have you searched for? I am not aware of changes in the US regulations, but Australian regulations seem to be going backwards e.g. maintenance on Experimental aircraft.
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