V0.7.0 a little too slippery?

  • I have not done a thorough test yet, but the version 0.7 Arrow III feels faster than prior versions. I first noticed it in the pattern. At 1200 MSL I was doing a 100 knots with gear down, 2000 rpm and 24 inches MP. That's a bit fast. It should be more like 90 knots with those power settings. TAS at 6K feet was 138 knots. I'll probably get to running a suite of tests to check TAS vs power VS altitude and climb rates, but I wanted to hear back from other folks. Does it feel faster or more slippery that V 0.6.0?

  • Hi Bernie,

    The only drag element that's changed (from memory) is the gear, down from approx 0.026 to 0.015. In terms of power, there have been minor adjustments but mainly to do with the peripheries of the engine, not the thrust tables, so shouldn't really affect speed.

    Any further info welcome, we can always adjust aspects back if they are having a detrimental effect.

  • Thanks Paul. It'll likely be a few days before I can do a methodical set of tests. I'll report back later what I find.

  • Doing a little testing now, she's definitely a bit fast. The speed isn't dropping as much as it should as the throttle is reduced, I'll post a chart in a bit. However, I found a typo @Delta558 on the engines.cfg so I'll redo it all again also

    Screenshot (341).jpg

  • @Delta558 I reverted the gear drag to 0.026 and it flies much truer to my real life expereinces. The "feels right" test for me is to fly a tight pattern gear down stabilized at 90 knots midfield on downwind. Simulate engine out abeam the arrival end of the runway. Keep the speed nailed to 90 knots and you should touch down in the first 1,000 ft of the runway. Don't add flaps until making the runway is assured. At .015 drag, IMHO, its too easy to make the runway in that scenario. Perhaps you were trying to tune for something else (perhaps takeoff performance over a 50ft obstacle) when you decreased the gear drag. In any event, its not that big a deal if you want to leave it at .015. The gear however on the Arrow has MUCH higher drag than most fixed gear aircraft if you want to compare to other aircraft as a sanity check. I think it was Piper's answer to the lack of a speed brake 😉

  • Versions 0.7.0 and 0.7.1 deviate more from book performance than prior versions I've tested.

    Top speed at 6K ft, std weather, max weight is 2 knots too fast. As you reduce power the delta between actual and book becomes much worse with actual being up to 10 knots too high at 55% power. This seems to be a regression IMHO. I'm going to roll back to a prior version and see if I can sort out when it was introduced. Best I can recall, it was present in .0.7.0, but I'll start working backwards and see if thats true.

    Oh, and one more thing, the EGT is behaving much different with the version 7 releases. The deflection used to max out just past 50% deflection which is pretty close to real life. It now maxes out around 80% of full deflection which is a bit wonky. I have no idea if the two are related, just thought I'd throw that out.

    I'll enter this as a bug report as well.

  • @BernieV just a quick follow-up, the regression in performance accuracy was not present in the version 6. I've rolled back to that version for the time being.

  • This is also what I was seeing

    Screenshot (350).jpg

    I also noticed that peak EGT would lower with increasing altitude. That was something I'm pretty sure didn't happen pre-7 but I also have no idea if that would be realistic or not.