Fixed Wing Flight Model (dev branch)

[x3kj 1247]

speaking of topical literature, if anyone needs a meaty good-night lecture, i can recommend Fluid-Dynamic Drag by Hoerner

[dragon01 902]

The latest improvements seem pretty nice, pretty much the only obvious problem are the speed-lift curves. DLC jets could also use greater low-speed (including post-stall) maneuverability, right now they feel like they have no TVC.

11 hours ago, gatordev said:

Something else to keep in mind with AoA indicators is that they're actually not indicating degrees of angles.  Most often, they're indicating "units" of AoA.  That graph that dragon01 posted seems to be saying that in some sort by indicating "normalized AoA," but it's important to understand that in different aircraft (or different aircraft publications), AoA doesn't always mean the same thing.

Normalized AoA does, however. That's sort of the point of using it in first place. "1" is the "critical AoA" at which the wing is fully stalled. 

 

As for in-cockpit indicators (IRL), they mostly seem to indicate AoA in degrees.

[Imperator[TFD] 444]

I'm liking these changes to the jets.  The Shikra is a real beast now and can gain speed in a straight up climb but doesn't have anywhere near the maneuverability that the Black Wasp II does.

[oukej 2911]

Low speed maneuverability - it can be increased but at a possible cost of way too short take-off distances, strong nose down tendencies (which are bad esp. for KB+M users) or players falling into a stall without enough obvious indices.

Otherwise Shikra should be more maneuverable. In subsonic speeds it can make 10G turns whereas Black Wasp only 9G.

[dragon01 902]

Fair enough. If you have the manpower, I'd suggest adding another "torque source", with strength dependent only on the current thrust. That would be the best way of simulating TVC. It's simply impossible to fake with parameters for aerodynamic controls (this is also why it's such a big deal IRL, it can do things that are physically impossible with aerodynamic controls).

[x3kj 1247]

I took the SU-25 out in DCS and made some tests for my own. AOA (degr)@ speed (km/h, IAS) to keep level at 1km alt:  (0.75@800, 1.25@700, 4@600, 5.5@500, 11.5@400, 14.5@350, >20@300). With full flaps in comparison its 2@350 for example

 

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Low speed maneuverability - it can be increased but at a possible cost of way too short take-off distances

three words: vectored engine simulation :P

 

 

[gatordev 219]

12 hours ago, dragon01 said:

Normalized AoA does, however. That's sort of the point of using it in first place. "1" is the "critical AoA" at which the wing is fully stalled. 

 

That was my point.  Your graph takes all of that into account.  As an interesting side discussion, generally, critical AoA is pretty much the same across all airfoils (within less than a degree) at sub-sonic speeds (usually around 18 degrees).   But that's not meant to argue anyone's point, as I think we're in agreement here.

 

12 hours ago, dragon01 said:

As for in-cockpit indicators (IRL), they mostly seem to indicate AoA in degrees.

 

Not in my experience.  AoA INDICATORS will use units that are NOT in degrees but instead in units (for example, the T-34C would stall at 26.5 units, on-speed was 20 units, and etc), and the units can be different from model to model.  AoA INDEXERS (there's a difference) will use the chevron/donut display and indicate the same basic information (slow/on-speed/fast).

[x3kj 1247]

10 minutes ago, gatordev said:

NOT in degrees but instead in units

... americans have an obsession with using arbitrary non-standard units, no susprises there. However, i would think that more modern planes use indicators showing degrees

[gatordev 219]

3 minutes ago, x3kj said:

... americans have an obsession with using arbitrary non-standard units, no susprises there. However, i would think that more modern planes use indicators showing degrees

 

I can't tell you what non-US-domestic aircraft use, but at the end of the day, many modern aircraft still use units (and/or indexers).  Right or wrong, it's still a standard (of sorts).

[dragon01 902]

An indexer doesn't show you the precise angle anyway. I think that "units of AoA" are mostly restricted to older "clock" indicators, which aren't featured on ArmA aircraft. All numeric AoA readouts on a HUD (the most common form in a modern aircraft, besides an indexer) that I've seen showed degrees.

[pooroldspike 129]

I spend about 5 hours a day on the KOTH servers, and whereas in the old days the skies used to be full of Blackfish VTOL's, nowadays they're almost empty since 1.70 because hardly anybody can fly them, including me.(sniffle)

Every so often somebody has a crack at it, but usually gets hung up on power lines or something.

Also, jets are now almost impossible to shoot down with the shoulder-launched Titan AA's fiddly new lockon routine, and the new wobbly horizon view has got many chopper pilots up in arms.  

[x3kj 1247]

1 hour ago, pooroldspike said:

nowadays they're almost empty since 1.70 because hardly anybody can fly them, including me.(sniffle). Every so often somebody has a crack at it, but usually gets hung up on power lines or something.

for the sake of constructivity (is that a word?) i'd say it would help if you could elaborate more on what you find difficult about them, so devs know what to change.

Could it be that its just the newly changed mechanics/ keybinds for transitioning between "vtol" and "fixed wing" mode ?

[Grumpy Old Man 3546]

1 hour ago, x3kj said:

for the sake of constructivity (is that a word?) i'd say it would help if you could elaborate more on what you find difficult about them, so devs know what to change.

Could it be that its just the newly changed mechanics/ keybinds for transitioning between "vtol" and "fixed wing" mode ?

 

Yeah, I don't get all those complaints about vtol changes either.

As of now there's no one explaining on what exactly seems to make them "unflyable".

It's a thing of 2-5 minutes to figure it out, the changes make it actually second nature flying a vtol since you now can control the transition.

 

Cheers

[Imperator[TFD] 444]

After publishing my VTOL tutorial video the number one feedback I've received has been from KB/M users and their dislike for the new 'percentage' throttle and how that affects their VTOL flying.  Personally I love the way VTOLs fly and now their advantages really shine through; fast speed transitioning to a landing in a tight spot with a larger cargo than any of the helicopters.

[jerminhu 25]

I'm having a issue with landing VTOL vehicles and need some help.

 

VTOL vehicles will now instantly throttle up to 100% once the landing gears touch the ground. The second they are airborne, they would then instantly throttle down to 0%, falling straight down and blow up.

[gatordev 219]

On 6/10/2017 at 6:19 PM, dragon01 said:

An indexer doesn't show you the precise angle anyway. I think that "units of AoA" are mostly restricted to older "clock" indicators, which aren't featured on ArmA aircraft. All numeric AoA readouts on a HUD (the most common form in a modern aircraft, besides an indexer) that I've seen showed degrees.

 

This is more for closure than arguing any one point, but...  I asked a couple of Super Hornet guys and they confirmed that their HUDs show degrees, as you said, however they also said other aircraft HUDs do show units.  My guess the switch to degrees in the jet world is because it's really not all that important how accurate it is, and the indexer will make it close enough when in the landing configuration.  But I'm not a jet dude, so that's a little bit of a guess.

 

On 6/10/2017 at 5:58 PM, x3kj said:

... americans have an obsession with using arbitrary non-standard units, no susprises there. However, i would think that more modern planes use indicators showing degrees

 

Units can allow for a more granular indication on where you are in the flight envelope.  That might be more relevant in some other aircraft.  As you say, more modern planes appear to tend towards degrees.  Either way, the indexer is going to be the go to indicator in the pattern.

[x3kj 1247]

19 hours ago, Imperator[TFD] said:

After publishing my VTOL tutorial video the number one feedback I've received has been from KB/M users and their dislike for the new 'percentage' throttle and how that affects their VTOL flying.  Personally I love the way VTOLs fly and now their advantages really shine through; fast speed transitioning to a landing in a tight spot with a larger cargo than any of the helicopters.

I can only imagine that they are used to tapping the w and s key with different frequency. Its just a matter of getting used to it... The new throttle mode gives much more granularity and controll in normal flight.

 

2 hours ago, gatordev said:

Units can allow for a more granular indication on where you are in the flight envelope.  That might be more relevant in some other aircraft.

Chosing a different scale on the indicator while keeping the physical unit does that as well... You can put 4 notches on a watch dial ,6 , 12, 60 and many other in between, thus determining granularity. Of course you can also convert them into some abritrary "time unit" specific to each watch and call it a day...  "May i borrow your watch?" "Yes sure, but remember to divide the time by 0.871."

[dragon01 902]

Units of AoA seem to be most often found on older clock indicators, which makes me think there was an engineering reason for that. Perhaps precision of early instruments of this kind was so low (determining AoA from inside the plane is not a trivial matter) that they were as granular as an indexer. It makes no sense to use degrees if you can't indicate with precision of at least one degree (indeed, it can be harmful, as pilots would assume the indicator is more precise than it actually is). Calibrating such an instrument wouldn't be a trivial matter, either. Later on the technology improved, but transitions are rarely fast in aviation industry and the units stuck. Jets (especially Superbug, which has to handle carrier landings) need more precision, and therefore use degrees, not to mention for "at a glance" readout they have the indexer, anyway.

[GamerOnkel 100]

 

Please add afterburner and Machscher cone

 

 

[x3kj 1247]

14 hours ago, dragon01 said:

Units of AoA seem to be most often found on older clock indicators, which makes me think there was an engineering reason for that. Perhaps precision of early instruments of this kind was so low (determining AoA from inside the plane is not a trivial matter) that they were as granular as an indexer. It makes no sense to use degrees if you can't indicate with precision of at least one degree (indeed, it can be harmful, as pilots would assume the indicator is more precise than it actually is).

 

No that does not explain it at all. Like i said, you can simply make the notches for readout spread further apart, the pointer thicker and the dial smaller. All those things reduce precision, without requiring introducing some arbitrary unit. HMI design 101. And if by indexer you mean "good/ not good" you can combine this into the numeral display by colored segment...If your readout is soo imprecise that you shouldnt even include numbers then i wouldnt call it an Angle of Attack indicator...  Imprecise AoA & G-load indicator example:

[gatordev 219]

Actually I think dragon01 is on the right track.  Yes, you can build an indicator that displays 12.2033 degrees (a notional on-speed profile), while also showing everything from 0 to 18 degrees (or more for high performance jets).  But for 1960's engineers, why not just build an indicator that that shows "20 units" as on speed and displays everything else in an easy to read display (26.5...rudder shakers, 29.0...stall, etc)?

 

Or to put it another way:  when I fly, I have a gauge that indicates Ng/N1.  It's precise enough to show me .1%, and I have limits that I have to maintain that are down to that granularity.  But do I actually look at that gauge like that?  No, of course not, it's too hard to read and it changes so fast, so I go off of color and position to tell me if I'm reaching a limit.  My airspeed is so sensitive it gives me indications down to single knots, but I almost never look at that indicator, instead I look at the tape to show me where I'm at (and any rate indication). 

 

I totally get your point, and I agree engineers can now make things that are in line with what you're saying, but usability quickly comes into play.  And I say that as someone who has to deal with a lot of very precise "things" on my aircraft but many are barely useful from the end user's standpoint thanks to the engineers.

[x3kj 1247]

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No, of course not, it's too hard to read and it changes so fast, so I go off of color and position to tell me if I'm reaching a limit.

Thats why properly designed indicators have the "optimum" point marked very visibly, and the acceptable limits marked as well with color coding or some other form. This has nothing to do with the units one uses, because you can position those "quick glance helpers" without needing a unit to match up exactly with that point or area.  If the indicator is too busy to read it at a glance, the notches need to be reduced by half, a fifth, or whatever instead (like i showed) therefore making the values inbetween imprecise and less important, but the display quicker to read. HMI design is an important aspect of engineering. If the design is bad, it is bad - simple as that.

[gatordev 219]

4 hours ago, x3kj said:

HMI design is an important aspect of engineering. If the design is bad, it is bad - simple as that.

 

A-MEN!  Unfortunately sometimes the operator doesn't get to pick the interface and we have to live with what the engineers give us. 

[dragon01 902]

Also, sometimes manufacturers stick with old schemes (even if they're inferior) for the sake of minimizing pilot retraining. Something that might have made sense back when it was introduced (or was simply the first thing they came up with) can carry on with minimal improvements in order to make sure that pilots of older aircraft can use it. Of course, this means new pilots get trained for the old scheme, as well, and by the next plane you design, those then-new pilots will be oldtimers... Generally, cockpits tend to have things added to them, rather than replaced. Even MFDs in the latest Dreamliner mimic the instrument layout that originated before WWII and was used on 50s fighter planes (though that one is a good scheme, so it's not like there's any reason to change that). The vehicle that probably illustrates it best is the Space Shuttle, which not only had two cockpits in its lifetime and despite looking different at first, it turns out that the actual functionality was pretty much unaltered, but also had its original flight controls (excluding orbital stuff) look very much like a contemporary military jet.

[jone_kone 158]

Any new findings on the flight model? Not able to test myself but would be interesting to see how much changes for 1.72