Echo38

So we have Solty saying that the aircraft noses up at full power even with full down-trim, and we have Sithspawn saying that he can get it to fly hands-off level at full power. If I got that right, then either Solty is doing something wrong with the trimming part, or else Sithspawn is mistaken about the hands-off part. Which is it? Or did I misunderstand what one of you two was trying to say?

Hmm. If they changed it, it would have had to been in the last month or so, because my engine-failure-from-not-warming-up was two or three weeks ago. However, it's likely that we're both overlooking variables. I do exactly as the DCS: P-51D manual recommends. Five seconds before first attempt (mags wait 'till six blades), one second before second attempt (mags still on from before, manual vague on this point), no oil dilution. Works for me, every time, at 74 degrees C ambient. Regarding that thread: yes, I have noticed that the engine "likes" fuel being "given" while the starter is turning. Both your "prime while turning" trick and my old "flip the mixture back and forth" trick start the engine more quickly & reliably than the "proper" procedure. Flipping the mixture back and forth while the starter was turning was such an easy way to start the engine (first try every time, if you don't screw up badly), that I suspect this method is exploiting a flaw in the simulation, and that it isn't something that would work in a real P-51. This is why I stopped doing it and started using a more true-to-life method.

I'm still a bit confused. Is the problem that you can't get the pitch to trim for hands-off level flight at max speed, by any method? Or is it that you can do this, but only by using a draggier method (namely, stabilizer trim) than you would use in a real 109 (which was tab-trimmed on the ground, to your specs)?

It is, but you can get it to "stick." With my current startup procedure, I intentionally make it "stick" because, IRL, I have two hands, but in the sim, I only have one mouse cursor. So, I click & hold the starter switch, then (still holding the mouse button) I move my cursor to the magnetoes, and I right click. This frees up my cursor while keeping the starter depressed. I now can (left) click the magnetos after the "sixth propeller" passes my gunsight. As soon as the engine starts (using this startup procedure, at this ambient temperature, it's always the second attempt for me, no exceptions), I click the starter to "unstick" it. You may be accidentally getting the starter "stuck" without realizing it; that's one of many possibilities. As Sithspawn said, a track could help us figure out the cause(s) of your problem. This is much too cold. The (sim) manual says that you should stay below 1300 RPM until you're at 40 deg oil. So 40 deg is the minimum you want to be at, not the maximum. You don't want to be taking off at 40 deg, much less below that. I've been taking off at about 60 to 70 degrees (I start taxiing at 40 and I do a proper run-up check before takeoff, which warms it up quite a bit). This may still be too cold, despite the coolant passing the redline on a 61" takeoff; one of the problems with some of these birds was that you could easily end up with the coolant too hot and the oil too cold.

I've done perhaps twenty startups (@ ~25 degrees C) & takeoffs in the last two weeks, and I only had an engine failure once, at any point in my flights. The one time I took off immediately after starting, without a proper warmup, I had an engine failure shortly after takeoff. Are you warming up in the manner described in the sim manual?

I hit the stopwatch start at the same time as I hit the gear key on my keyboard, and I stopped the stopwatch as soon as the light was green and the noises stopped. You make a good point--I should do external camera instead of relying on the lights & sounds.

I've never understood why some people on the DCS forum--of all places--have a "lol who cares about realism" attitude. What are you even doing here? The thing that makes the max-fidelity DCS aircraft unique is the max-realism approach. If you don't care about realism, there are much more smooth-running, well-populated, and easy-to-play flying games out there, in which you'd (doubtless) feel more at home. Some of us are here because we want it to be exactly like flying the real airplanes. That's fun. The more like being in a real airplane, the more fun--with the sole exception of real {death, pain, & aircraft loss}. No one wants that, and it's stupid to imply that {wanting it to be exactly like flying a real warbird in every other area} should also mean wanting real {death, pain, & aircraft loss}. Are you serious? I can't tell if you're being thick or just trolling. Hell, the only reason I'm here in a flight sim instead of flying the real deal is that you need to be rich & healthy to fly for real.

Curiouser and curiouser, cried Alice. Six seconds seems to be standard, then, in modern restored P-51Ds, at least, judging by this collection of videos. Quite a bit slower than the ~3.9 seconds we have right now in the sim, but much faster than the "10 to 15 seconds" of the manual. Why, then, did that manual give such a large figure? Was the USAAF pilot guessing based on feel & memory, or did the example he flew, perhaps, have weaker hydraulics? Do modern restorations/replicas have stronger hydraulics than wartime examples?

Another thing that occurred to me--maybe, just maybe, something's happening with the vibration of the aircraft on the ground? My accelerometer always shows +-0.5G before I even get to the runway, even when I reset it several times (after startup, after warmup, and before takeoff). I wonder if the gyro is being effected by this heavy vibration. Just a shot in the dark.

50% more isn't a big difference? If we were talking about airspeed instead of gear time, that'd be the difference between 300 MPH and 200 MPH. Granted, we're talking about gear time, and so the difference (in that video) was about two seconds--which, I'll concede, isn't that terribly much--however, that 6-second example was the most optimistic RL example that's been given in this thread so far. If the quickest RL example we could find is still 150% of the time in the sim, that supports my suspicion that the sim is in error. Then, too, it's been noted within this thread that it's possible that these videos are showing extensions which are occurring more quickly than they'd be in the air, because of differences in conditions (such as slipstream, external hydraulic assistance, modernized hydraulics, etc.). Using an outlier (e.g. the fastest) in a sample set, for your reference point, isn't an accurate way of doing things. So, in our "best case scenario," our sim P-51 is still dropping its gear in ~66% of the time that { the fastest RL example we found } is, and ~27–40% of the time that a RL manual suggested it should be. Something doesn't add up. That's a big margin of error in any case--looking at it in the most optimistic way, the margin of error is still twice the normally accepted margins for flight sims. Am I missing anything?

Same here. I leave it caged from engine startup to engine shutdown. I find it difficult to believe that the instrument would have been included if it were unreliable to this extreme.

Most 109's didn't have it. In fact, that's the first time I've seen a picture of a 109 with a mirror.

I don't understand how I'm supposed to use this for IFR flying. It accumulates more and more error at a rapid rate, even when I'm flying more or less straight & level and more or less coordinated. If I were trying to fly in clouds, I'd lose use of this thing within a couple of minutes, and have no way to realign it ('coz I have no good way to know when I'm actually level, if horizon isn't visible and the gyro horizon isn't reliable). I know I could technically use the turn & bank indicator to more-or-less align it, but if I'm constantly (every few minutes) having to us the turn & bank indicator because the gyro horizon is off again by as much as 20 degrees, then I might as well be stuck with just the turn & bank indicator. I know I never experienced this effect (that is, of the gyro horizon gaining ~20% error within 15 minutes of normal flying) in the Cessnas I flew IRL. Hour-long flights with circles-around-a-point and S-turns over a line didn't result in any noticeable errors. I must question if this effect isn't overdone in DCS, since I can't think of a reason why the P-51's gyro horizon would behave differently than a modern one.

With the kind of approaches & landings I do, the time to deploy the gear is important, because I have a narrow window for deploying them (compared to standard low approaches under power), and thus, the longer the deployment time, the greater the difficulty in getting it right. If it's currently wrong by as much as 50% (not yet determined), then it's making my dead-stick approaches significantly easier than they should be--by making it half as difficult to make my airspeed/time window as it would be IRL. I suppose if one only does normal, at-power approaches, then this might seem like a nit-picky issue, but the apparent error is large in factor and has a very noticeable effect on my touch & goes. At any rate, a 50% error (if it exists) in a high-fidelity sim must be corrected, regardless of how little some notice it; acceptable margin of error for a high-fi sim of this sort is generally regarded to be ~10%.

Even "original" airplanes tend to be heavily restored and/or modernized. I don't think any of the ones flying are entirely in their original condition. I dunno about this one in particular, but bear the previous in mind. Four seconds still seems awfully far out of the margin. Perhaps whoever wrote that bit in the manual was being sloppy & guessing, the USAAF manuals do contain examples of this. But the sim could also be in error; it happens.

Is it possible that the gear retraction/extension system has been modernized in some of the replicas, with the result that they raise & lower more quickly?

Well, there was that one time Mr. Maddox refused to acknowledge that the Browning M2 dispersion pattern was three times larger than RL test documents stated it should be, under any given conditions. Yes, that's a 300% margin of error; he apparently found that acceptable, given that he insisted that his insane figures were correct, all the way up to the point that the publisher stepped in & ordered him to fix it.

Rise of Flight does use rough fluid physics calculations ( ), but, other than that, yeah, I haven't seen another combat flight sim/game that uses fluid physics, blade element theory, etc. Aces High used a { 32 lift, 32 drag, 4 thrust, >1 weight } vector system (see attached image), and old IL-2 used a simple vector system. Dunno about CloD. So, I'd agree about "apples & oranges," since RoF isn't WWII, and none of the other ones use fluid physics, with the possible exception of CloD (which I haven't yet examined). Not much point in saying "but the older games did it such-and-such a way" to support the idea of making it so in DCS.

Re-saving the mission didn't fix mine. They're fairly small "cuts," I might've simply not noticed them before.

This manual here: http://www.scribd.com/doc/34811808/North-American-P-51-Mustang-Pilot-Training-Manual ... says (on page 17) that lowering the gear should take 10 to 15 seconds. But I'm continually noticing that in DCS, it takes much less. I just timed it with a stopwatch at 4 seconds. What's the reason for the discrepancy?

Same here. Thanks; I'll update the mission and see if that fixes it.

Getting smaller ones at Batumi, while taxiing across the tarmac. Weren't there last version.

What?! Why?

Where did you hear that?

A new 109? Good news indeed! So tired of hearing about "one less," so nice to hear "one more." This is an exact replica? Original engine, or also replica? I gather some "unnoticeable" things (e.g. spark plugs) really need to be modernized for safety reasons, but it's always wonderful when the replica is otherwise exact, engine & all.