Zoom Climb Test Methodology

[Stoney]

Gents,

Just curious as to a method for comparing zoom climbs in-game.  I had thought about:

Accelerate aircraft at sea level to 300mph TAS, then hit [alt-x], record peak rate of climb, and altitude at which the autopilot began introducing nose-down pitch trim.  Repeat this process at different speeds and starting altitudes.

I've got some other ideas, but they would be very dependent on the pilot, and very hard to maintain precision.  What factors from the above method would cause false comparisons? 

[morfiend]

Stoney ever consider auto angle?? that would allow equal angles of attack,say zoom at 60 degrees 45 degrees etc.

[Stoney]

Stoney ever consider auto angle?? that would allow equal angles of attack,say zoom at 60 degrees 45 degrees etc.

How would you know you had a precise pitch angle?  We don't have any instrumentation in the cockpit to know what pitch angle we're using--it would simply be a swag.

[TequilaChaser]

you might 1st want to define your definition of a zoom climb.......

some people refer to a zoom climb as , as you put it climbing at a set rate of climb angle ( meaning Alt X )

others sometimes refer to a zoom climb as morefiend mentioned, pulling back and climbing at different angles  45 degree nose up, 60 degree nose up, etc...

while even others ( this is my thoughts as well , btw ) think a zoom climb is where you pull up nose above the horizon in a smooth quick motion, anywere from 45 to say 70 degrees while moving along at a significant amount of speed ( 300 to say even 450 ias, or could be slower say 225 ias perhaps ) then unloading the stick ( unloading the G's to either your normal 1 G + , or to a more extreme of "No Load Zoom Climb" meaning you rest the G-meter on zero G's..........

the latter, is your fastest zoom climb possible because of being at zero G's ........ as you begin to level off at the top of your zoom climb, you should still be around 180 to 220 IAS ....which is most times enough speed left to maneuver with if the need arises.....

so, what definition do you want to test  towards?

[BnZs]

The simple method of simply diving to 400 or so, doing say a 3g pull up to vertical and using auto-angle works well enough.

A word about "unloading" in a zoom climb...

When the airplane is pointed straight up, the airplane *is* unloaded.  The G-meter will be at 0. So induced drag is no longer a factor, the method yields a *pure* test of the airplanes thrust and inertia vs. gravity and drag. And that is what we are after, is it not?

[TequilaChaser]

BNZ, that is why I asked him for his definition of what he considers a Zoom Climb........

got to lay the definitions, the methods/logic and the testing procedures/criteria out 1st........

using Alt-X is just utilizing the games ( the planes ) pre-determined best climb rates/angles..........unless someone ( whoever is testing ) has gone in and changed the preconfigured settings ( but I think these reset each time one launches a new Plane, correct? )


on a sidenote........BNZ, do you think if you were doing 400 IAS at say 3,000 ft alt...and performed a 3 G pull to Pure Vertical Climb.( as you put it a Vertical "Unloaded/ 0 G Climb ) would you climb faster and higher than if you was to fly at 400 ias at 3,000 ft and pull up nose high to roughly 60 degrees/70 degrees above horizon with a very quick & smooth 5 or 5.5G pull and unload to 1G+ or even unload to "No Load/ 0 G climb?  lets use a P51B for the test platform...

[BnZs]

Well TC, I don't understand the value of angles other than the pure vertical for testing this.

First, if you can tell that you are at exactly 70 degrees pitch say, you're a better man than me. Perpendicular to the horizon is pretty easy to determine though.

Second, most of these planes will climb with the nose held at very high angles, even below Vy. So where does "zoom climb" performance end and "climb-climb" performance begin?

Third, the idea of pulling up to some high pitch angle, then pushing forward on the stick to 0? That will level you out rather quickly, will it not?

Fourth, I believe zooming straight up best reflects vertical capability as is useful in actual ACM.

Fifth, I believe the only reason people are trying to come up with more complex methodologies is that it has been proven that planes with excellent power-loading perform as well or better in the vert than planes with low power-loading and excellent mass/drag ratio in this game, and some folks just don't want to accept that. 

BNZ, that is why I asked him for his definition of what he considers a Zoom Climb........

got to lay the definitions, the methods/logic and the testing procedures/criteria out 1st........

using Alt-X is just utilizing the games ( the planes ) pre-determined best climb rates/angles..........unless someone ( whoever is testing ) has gone in and changed the preconfigured settings ( but I think these reset each time one launches a new Plane, correct? )


on a sidenote........BNZ, do you think if you were doing 400 IAS at say 3,000 ft alt...and performed a 3 G pull to Pure Vertical Climb.( as you put it a Vertical "Unloaded/ 0 G Climb ) would you climb faster and higher than if you was to fly at 400 ias at 3,000 ft and pull up nose high to roughly 60 degrees/70 degrees above horizon with a very quick & smooth 5 or 5.5G pull and unload to 1G+ or even unload to "No Load/ 0 G climb?  lets use a P51B for the test platform...

[Strip]

I would say the most accurate way would be to go Alt-X and pick a standard speed. When the autopilot noses over and climb rate drops below 1,000 fpm stop the test. I believe most planes will even lose some altitude after a zoom climb in autopilot. This would give you identical control inputs and flight paths. Peak FPM climb will depend on a few variables and for me personally isnt that critical.

Your comparing relative stats in order to establish a plane "rank" right? If so the specific flight path need not be perfect.

However, going pure vertical may most accurately depict what you would do in the game.

Strip

[Stoney]

Well, a test of any definition of "zoom" is not reliable unless we can constrain the flight parameters to something that is quantifiable, repeatable, and capable of precision every single test.

I agree TC, that there are different types of "zooms".  The problem as I see it is that when using a 3g pull to auto angle, you'll not know how precise your final climb angle is.  On the other hand, using auto-climb will allow a lot more precision between aircraft and give something that is repeatable.  The reason why I asked the first question was to find out if anyone had any issues with the methodology, or if the methodology wouldn't illuminate anything of substance.  

So, if we define the "zoom" as accelerate the aircraft to 300mph TAS and then engage auto-climb until nose-down pitch trim is introduced, does anyone have any problem with the methodology or think that the test will not reveal anything of substance?

Lastly, BnZ, going vertical is not the most efficient method of recovering kinetic energy (speed) and turning it into potential energy (altitude).  There are formulas which I will include at a later date that will prove this correct, so for now, you'll have to just push the "I believe" button, or not.  The AoA that maximizes lift and minimizes drag is typically close to the AoA for best climb rate, which also corresponds to a speed.  In-game, this is close to the auto-climb speed.  It changes with altitude due to the drop in dynamic pressure, but typically only changes 5-10 mph.  The reason that I believe the auto-climb will be the best way to measure (apart from the precision and repeatability) is that the way the trim system in AH works (to my knowledge), is that pitch trim positions are mapped to speeds for each aircraft.  It doesn't matter what attitude the nose is at, the pitch trim matches that of the speed of the aircraft.  That's why you have such a hard time getting the nose down when you go "over the top" in a loop, or pulling out of a very high speed dive with combat trim engaged.  So, when you engage auto-climb, the game automatically trims the aircraft for that best climb rate speed, or Vy.  It doesn't matter how fast you are going.  I would imagine that for some aircraft, the pitch trim may reach its maximum trim position during the climb, but we'll have to simply accept that, in my opinion.

Now, to answer your zoom climb to climb climb question, the transition begins when you reach best rate of climb speed out of the zoom.  So, when you decelerate to 160mph IAS, for example, out of the zoom, that is the moment that you transition from zoom to climb.  That is also the reason why I chose the moment that the auto-climb begins to institute nose-down pitch trim to signify the end of the zoom.

You can call it a ham sandwich test instead of a zoom climb test if you want.  I just want to know if this methodology will give us any sort of significant comparison between aircraft?  Anyone, please correct anything I've said wrong so far, or criticize the methodology, from an aerodynamic standpoint.

Thanks.

[moot]

Pure vertical and some other shallower test like in the first post would complement each other pretty well, I reckon.

[Stoney]

Pure vertical and some other shallower test like in the first post would complement each other pretty well, I reckon.

How do I ensure precision in the pure vertical?

[BnZs]

How do I ensure precision in the pure vertical?

Look out the side to make sure you're at right angles to the horizon, hit shift-X, see how much alt the plane regains before it runs out of speed and stalls.

[moot]

I can't see any perfect way.  I'd work it out so I was doing some arbitrary speed at the start of measurement (say 400mph), and then auto-angle.  You'd have to have the same angle everytime and exact vertical might not work with auto-angle, since IIRC it acts funny near the vertical.  But if you found some tell-tale like when the chase view mode (F4) camera starts to roll to keep its position relative to the plane as you near exact vertical, then you could set the angle to a near enough value for all planes.  

The flaws are, first, that this is pretty inaccurate but IMO still at least a little useful.  Second, on some planes the auto-level fails pretty bad.  On a few planes it fails much earlier than the rest.. e.g. the very torquey ones.  SpitXIV, K4, etc.  But I think the data would still be worth having despite its low resolution.

[Strip]

Stoney,
Here is an easy way to fly pure vertical......set the time for noon and point the pipper towards the sun. I think you can turn the brightness down in the arena settings. Worse case set it for midnight and use the moon as a refrence. Use the G-meter to control rate of pitch up and climb angle. If you want 70 (or ?) degrees set the time so the sun is where you want it.

Edit:Just changing the sun color to blue makes a nice target for a vertical zoom.

<S> Strip

[Noir]

on a side note : autoclimb default speed changes with the planes