Zoom Climb Test Methodology

[Anaxogoras]

Here's how I measure zoom climbs:

Dive the aircraft to ~50' asl, engage auto-level.  When the airspeed drops to 400mph ias, I engage climb-on-speed set to 100mph.  Once the maximum pitch is attained (about 80 degrees), I engage auto-climb-on-angle.  Record maxiumum altitude achieved.

[hitech]

The auto pilot will respond differently on all planes.

[TequilaChaser]

The auto pilot will respond differently on all planes.

Hitech,
just the auto-pilot Level?  or all the auto pilot features ?    X  = autopilot level, Alt X = autopilot climb,  Shift X = autopilot angle

[Old Sport]

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.

You might try this.

Get a piece of string and put a piece of tape at both ends – you are going to use this as a calibration line across your monitor for aligning the horizon.

Use an AH map with ocean and set the arena parameters for clear visibility to the horizon.

Up a plane, level out at 3,000 ft or so, and set auto pilot for level flight.

Go to F3 (outside view) and then go to side view of the plane (4 or 6 on the keypad) so that you can see the horizon. Probably best to find a small weight to put on the key to hold it down so you don't have to.

Open the clipboard – E6B – size it and move it so you can still see the horizon.

Reach the speed you want to run for your tests.

Pull back on your stick till you get an angle you like, set auto pilot angle to hold the angle and keep wings level. Quickly tape the line so that it lays on the horizon.

Now you have your calibration line for angle of climb.

When testing planes with superior climb the horizon line on screen will drop a little because of altitude, so it's important to get the angle set quickly at the start.

Monitor E6B for speed. When the plane decreases to a certain speed, say 140, press F1 to hop back in the cockpit, level out and check your alt.

Best.

[hitech]

Hitech,
just the auto-pilot Level?  or all the auto pilot features ?    X  = autopilot level, Alt X = autopilot climb,  Shift X = autopilot angle

All of them.

[Widewing]

I have a very simple visual test control... Offline, I make sure the time is 12 noon (lock the time, if not already so). I take off, accelerate to a specific speed. As I attained that speed, I pull the nose vertical (3g) until the sun is in my windshield. I keep it there as long as possible. When no longer possible, I state such for the film. Do that for all aircraft and you have a reasonable standard for comparison.


My regards,

Widewing

[Strip]

I mention that earlier widewing....it does a respectable job. Changing sun color takes away most of the corona effect.

Strip

[Baumer]

This is the test methodology I'm currently working on. It seems to be a pretty consistent methodology so far, however it's not a true "unloaded" zoom climb.

1.) take off with 50% fuel and lightest internal gun package (film on auto start)
2.) level at 500 feet and accelerate to maximum military speed (zero climb on the E6B) (I use CT and auto pilot to ensure the correct altitude to less than +/- 20 feet)
3.) set auto speed to 100 (lowest speed allowed)
4.) as soon as I reach max speed (E6B climb = zero) note max speed (TAS & IAS)
5.) then engage auto speed (with and with out WEP)
6.) observe climb and E6B during climb
7.) test is complete once IAS drops to 100, save film for later review

so as a comparison of my first few tests here are the numbers for the Me262 and the P-38L

Me 262
Initial TAS: 521mph
Initial Alt: 500 feet (exactly from the film viewer    I'll never get that lucky again )
Max G: 2.4
Climb Time: 42 seconds
Max Alt: 10,670 feet
Zoom Alt: 10,170 feet
Zoom FPS: 242.14 feet per second
Zoom FPS / Initial TAS: .464765560 FPS/PMPH

P-38L (WEP on climb)
Initial TAS: 334mph
Initial Alt: 505 feet
Max G: 2.6
Climb Time: 25 seconds
Max Alt: 5,005 feet
Zoom Alt: 4,500 feet
Zoom FPS: 180 feet per second
Zoom FPS / Initial TAS: .538922156 FPS/PMPH

So while the 262 climbs higher, the P-38L actually is more efficient in the climb test.

You guys are much smarter than me, so I'm sure you'll come up with a better test methodology that's repeatable.

    Baumer  (Jr. test pilot)

[Strip]

Baumer thats actually a pretty good methodology and its quite interesting. By that test CoAlt-CoE the P-38 would out zoom a 262. To me this is the most useful information. Knowing who will fall out the sky first is a great bit of knowledge when deciding whether to go vertical.

Strip

[gripen]

Sorry about talking about competing game but I made last year some dive and zoom testing on Il-2 using a app called Autopilot by LesniHU. It had a command to fly at constant pitch but I found out that using speed and variometer data it was possible to determine angle of the flight path. This worked out beautifully once the plane was settled to the steady climb or dive and I told about that to LesniHU. Within couple weeks he had implemented the idea to the Autopilot and testing was quite simple after that. The results are not important but picture below gives an idea about the paths on 20deg dive and zoom. There is also undocumented command for constant g pullout but I have not really tested it yet.

[Strip]

Id love to fly the last two in AH....   

[morfiend]

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.

artificial horizon is in every plane{I think} ussually displays 30 dergrees and 60 degrees....

[Ghosth]

I'm with widewing, .time 12 0 0 sets the time to high noon and locks it.

Pull from a given set speed, put the sun in your gunsight.  Different planes are going to need different exit speeds.
Tiffy is going to need more than the D3a1. So note the exit speed you pulled out at and final alt.

[Widewing]

This is the test methodology I'm currently working on. It seems to be a pretty consistent methodology so far, however it's not a true "unloaded" zoom climb.

so as a comparison of my first few tests here are the numbers for the Me262 and the P-38L

Me 262
Initial TAS: 521mph
Initial Alt: 500 feet (exactly from the film viewer    I'll never get that lucky again )
Max G: 2.4
Climb Time: 42 seconds
Max Alt: 10,670 feet
Zoom Alt: 10,170 feet
Zoom FPS: 242.14 feet per second
Zoom FPS / Initial TAS: .464765560 FPS/PMPH

P-38L (WEP on climb)
Initial TAS: 334mph
Initial Alt: 505 feet
Max G: 2.6
Climb Time: 25 seconds
Max Alt: 5,005 feet
Zoom Alt: 4,500 feet
Zoom FPS: 180 feet per second
Zoom FPS / Initial TAS: .538922156 FPS/PMPH

So while the 262 climbs higher, the P-38L actually is more efficient in the climb test.

You guys are much smarter than me, so I'm sure you'll come up with a better test methodology that's repeatable.

    Baumer  (Jr. test pilot)

Using the "sun in the windshield" test, I find that the Me 262 has miserable zoom climb ability. I set a base line speed of 344 mph, that being the max speed of a P-38L at 50 feet ASL. I tested by pulling into a pure vertical climb at 4g, keeping the sun in the windshield as long as possible, but also noting where vertical speed became zero.

All test samples were either dived to speed or, in the case of the 262, P-51D and Yak-9U, were allowed to accelerate to speed (to make sure max thrust was available).

I tested a Me 262 with full fuel, P-38L with full fuel and an A-20G with full fuel.

Takeoff Weight (zero fuel burn) were:
Me 262: 15,685 lb
P-38L: 17,700 lb
A-20G: 22,000 lb (18,738 lb @ 25% fuel)

Rounded to nearest 50 foot increment, peak altitudes starting at 344 mph from 50 ft ASL were:
Me 262: 3,600 ft
P-38L: 4,350 ft
A-20: 4,200 ft (dropping fuel to 25%, the A-20 managed 4,350 ft)
For reference, I also tested two other fully fueled fighters, but didn't record weights.
P-51D: 4,300 ft
Yak-9U: 4,400 ft

Repeating the test using auto-climb typically resulted in far less altitude gained, with the 262 most adversely effected.

I prefer pure vertical zoom testing for one simple reason: It better defines what you will encounter in a fight. It also demonstrates why trying to escape a Co-E A-20 in the vertical is futile. Likewise, it shows why a low and slow Me 262 is usually dead in short order.


My regards,

Widewing

[Baumer]

Widewing did you use WEP during your tests? I assume you must have, to get 344mph with the P-38L I was just wondering.

The reason I choose to perform my test at max speed (no WEP) was to achieve a consistent result for all aircraft. In my opinion, by selecting an arbitrary airspeed it changes the premises of the original question. By running the test at the assigned speed, you are in essence comparing an aircraft at it's maximum E state (P-38L) to one that's only at 64% of it's potential E state (Me 262).

However, I do see the value of this kind of testing it equate it to "real world" situations. But, there needs to a much more comprehensive set of tests done at various speeds to best understand an aircraft's zoom potential.