FM Question/New F4U's climb slower??

[F4UDOA]

HT/Pyro

I was running through the new F4U FM's and I noticed the low alt climb rates seemed a little low fuel levels so I ran a few climb test.

Climb to 20,000FT
180 Gallons of fuel= 1080LBS (50% in F4U-1/1A and 75% in -1D)
Fuel burn = 1
Test method takeoff level on runway, accelerate to 150MPH engage WEP and auto climb, start timer. stop timer at 20K. WEP expires after 5 minutes do NOT re-engage.

1. F4U-1(Birdcage) with Water 50% fuel= 8 minutes 4 seconds

2. F4U-1A with Water 50% fuel= 7 Minutes 19 seconds

3. F4U-1D With Water 75% fuel= 7 minues 21 seconds

4. F4U-1D With Water 100% fuel= 7 minutes 45 seconds<==about 45 seconds slow.

The F4U-1A/1D should reach 20K in roughly 7 minutes flat. They appear to be an average of a couple of hundred FPM off. The F4U-1 is also slow considering I tested it about 400lbs light and it is still slower than listed time at it's reduced weight.

I'm guessing there is some hidden weight attached to the new FM's or the climb FM of all the F4U's has changed from the listed climb rates from AH2.

I think it is the former as it affects all F4U's the same.

[Kweassa]

Another possibility could be that simply your experimentation had flaws.

 This is not a direct criticism pointed at your own methods, but rather an explanation on why it might be problematic to compare in-game climb performance with real-life performance by engaging "auto-climb".

 For one thing, auto-climb is not known to be the most efficient method of climbing in Aces High. Despite popular beliefs "auto-climb" is actually "auto-speed" - the plane will stabilize its general heading and its balance in the roll axis, while adjusting its pitch to keep the plane stable at a certain set speed.. and therefore, it does not take into account a number of factors that might effect climbing efficiency. The optimal speeds for climbing might change throughout the range of altitudes a plane travels - which, is clearly more than the "auto climb" feature might handle.

 Therefore, my guess is that the auto-climb can provide an objective reference of climbing capabilities only when it is directly compared with other in-game planes also using auto-climb.

ie) When one compares the Bf109 with the F4U, the difference in magnitutde of climbing capabilities between the two planes will be presented at a relative scale: one will first engage the Bf109 in auto-climb, and then compare it with the F4U engaging in auto-climb. It is highly probable that both the 109 and the F4U will not match real-life figures per se, but rather only the relative difference between the two planes engaged in auto-climb, will match that of the relative differences between real-life figures.... for instance, if real life climb figures show a 30% advantage in climb in favor of the 109, the same 30% ratio will show between the auto-climb results compared, despite the ultimate "time to reach X altitude" figure might not match that of real-life.

 The only way to actually try and match real-life climbing figures with that of the game, IMO, would be to look up historical documents and see what sort of methods the actual planes used, to perform climb tests. One particularly necessity would be try to find out the average climb speed the plane used in actual real-life testing, and adjusting AH "auto-climb" speed to match that.

 If there's one thing I've found out during my own series of comparative tests in turn performance, it is that coming up with an objective and mechanical testing method is incredibly difficult. My suggestion is that you should try to consult these boards and have a discussion in which testing method might provide the results you are seeking... before any testing is actually done in the first place.

 To the extent of my knowledge, every piece of information we have for AH planes were actually tested by different people with different test methods - which seriously questions the objectivity of it all.

 As a side note, I myself do not trust other people's results in turn performance testings, for example, because I find serious faults in the objectivity of their testing methods - whereas my own tests were devised to set each of the plane's to their mechanical limits and leave out as much human factor as possible, others were rarely so thorough.

 A stark example of why a totally objective method of testing is required can be observed from one of my own test notes, linked in my sig below; "The AH Compendium of...."

[F4UDOA]

Kweassa,

I would say that test methods are always in question however the differance in climb was immediately noticable in low speed maneuvers at low alts. This led me to initiate the test in the first place.

I generally try to test in more "real world settings" than flight simm settings however the auto climb does a very good job in maintaining a consistant IAS that matches the best climb speed of the F4U (approx 155MPH IAS). give or take almost +/- 10MPH will not affect climb rates or times very much so climb method has some slop built in to it. However the loss of time is roughly 45 seconds over 20,000FT which may not sound like that much but it is fairly significant in average climb rate.

The F4U-1D is now reaching 20k at 7.45 which is an average of 2580FPM which is up from 7.00 which is 2857FPM.

This is almost 300FPM a slow climbing aircraft like the F4U does not have to spare.

[Badboy]

Originally posted by Kweassa
As a side note, I myself do not trust other people's results in turn performance testings,

Nearly choked on my coffee when I read that  

Badboy

[humble]

on the hogs has changed with the new release. In some aspects it appears to be a bit better but its performance as a pure angles fighter has been affected more than a little. If and how the changes affect climb to alt I dont know....

I do know that the hog has lost a bit of its "zoom". I noticed the nikki for example retains E comparatively better vs the hog then it did before (or at leat seems to)....

[Kweassa]

Nearly choked on my coffee when I read that

 It doesn't necessarily mean I dismiss other tests altogether. Rather, if there may ever be serious disparities in certain figures, I'd have an unwaivering faith in the faultlessness of my own figures, than believe someone else's, which were gained from questionable test methods, according to my own standards.

I generally try to test in more "real world settings" than flight simm settings however the auto climb does a very good job in maintaining a consistant IAS that matches the best climb speed of the F4U (approx 155MPH IAS). give or take almost +/- 10MPH will not affect climb rates or times very much so climb method has some slop built in to it. However the loss of time is roughly 45 seconds over 20,000FT which may not sound like that much but it is fairly significant in average climb rate.

 It could be due to a variety of factors..

 For instance, how much trust do we give AH's FM when the altitude ranges go over 'non conventional' ranges seen in gameplay? Over 20k? 25k? 30k? Frankly, I'm not so sure about that part.

 Another could be a variety of real-life factors that are not introduced in-game, such as specific cowl settings, radiator flap settings, etc etc.. For instance, in IL2/FB a certain level ofaccurate testing is possible because the game allows the players to set specific supercharger/mixture settings and radiator cowl/flap settings as well. This became extremely handy when a certain band of Luftwaffe fans actually compared in-game tests with the plane in the exact configuration of engine settings and radiator settings, as proposed in real life test documents. They found some numbers did not match, and the fact that the FM had problems became unquestionable since the testing configuration matched that of real life configuration almost exactly. Can we have the same amount of confidence in our own tests with Aces High?

 Thirdly, (a personal question), what was the reasoning behind engaging ADI(wep) right after takeoff? Could the results be different if you perhaps engaged it somewhere around 17~18k, when the planes starts to reach higher altitudes? Again, this calls for a separate discussion in what kind of testing method we should use, to hold AH's numbers against real life figures.

 My 2cents.

[Pyro]

If you're not loading up any external ordnance, there shouldn't be any weight or performance difference from the previous version.  I would try the same test with the previous version.

[Bronk]

Originally posted by Squire
Whats the empty weight difference between the F4U-1A and F4U-1D? They arent identical.

1a has wing tanks, 1d doesn't.


Bronk



Edit: squire pulled his post.

[Squire]

Ya I took off the post when I realised the debate isnt about the differences in the 1A/1D its about the F4Us climb to 20k compared to version 2.08.

[AKDogg]

1 thing i noticed in the -1 and -1a hog is fuel load out are not the same.  When u take 75% fuel, it gives u 75% in wings and 75% in main.  Is this correct as I thought the -1 and -1a are same plane all except for paddle prop and canopy.  The -1 hog loads 25% in wings tanks and 100% in main if u take a 75% fuel load out.

Anybody got any info on this?

[Squire]

The load is the same in gallons, 272, its just pumped in differently, but thats no big deal.

[Squire]

As far as the climb rate goes, I also have to wonder wether the 7 minutes to 20k that was done in real life was done with ADI the entire time. I find it hard to beleive the pilot would shut it off after 5 minutes, when he's trying to get the best time to alt time. The AH tests above are done when the WEP is off after 5 minutes, and we all know the 5 min limit was nothing more than a suggested limit in real life, and not always adhered to, unlike AH where its shut off for you?

[F4UDOA]

Squire,

You know that is a great question. I have to find where exactly but I do remember reading that the climb test were done at WEP for 5 minutes then at mil power. BTW the internal fuel load on the -1/-1A is 361 gallons. If you select 25% you will get 90 gallons.

Pyro,

Thanks for looking into it. My guess was extra weight was in there somewhere. I kept checking my gear flaps and ordinance but I had none.

I have a chart from the POH for the F4U-1D (It is a pretty common chart). It shows the F4U at Mil power climb times to 20K at weights from 9,000lbs on up. Basically every 1,000lbs equals 1 minute to 20,000FT. That is roughly 350FPM. When I tried that on the -1A it was much slower than I expected. That is what got me started in the first place.

Here is a F4U-1A climb chart with paddle prop. The mil power is significantly different.

[Squire]

Is that a chart of an actual test? or just a calculation?

Because if its an actual test it would indicate the pilot did an ADI climb to 38,000 feet without letting up. Might not have been great for the engine, but they are trying to establish parameters.

I realised after giving it a think, that its really academic anyways, the chart shows to do 20,000 feet in 7 minutes, you gave to use ADI the entire way, wether its a calculation or not. If it was a 5 minute ADI climb, the chart would indicate that, but it doesnt.

[Badboy]

Originally posted by Kweassa
It doesn't necessarily mean I dismiss other tests altogether.

Phew, after analyzing flight models now for around 15 years that's a relief

Badboy