Small tool for dive-zoom climb performance estimate

[JtD]

From reading this forum here I've gotten the impression that dive-zoom climb behaviour is often perceived a little bit wrong. Which is why I put the simplified physics into the attached, small Excel sheet. It is supposed to allow folks to get a more realistic expectation and maybe also a better understanding of dive-zoom performance.

 

Basically it has a very small input area, where you can roughly describe an aircraft, a couple of calculation sheets and two sheets containing charts. In the example, I'm using the Fw190A-3 and Yak-1 and compare them side by side. One chart sheet shows absolute figures of some key quantities, the other sheet shows relative performance. In the selected case, it can be seen that the aircraft reach about 800 km/h in the dive, and fail to regain their original altitude (absolute figures sheet). It can also be seen that initially the Yak-1 gains a little on the Fw190, but then the Fw190 easily pull ahead, being faster, and eventually ending up about 60m higher than the Yak at about the same speed (relative performance).

 

Please keep in mind that any 20 year old flight sim has more accurate algorithms than this tool, don't use it to prove FM issues. It's merely for a better understanding.

 

If you have questions or remarks or input for improvements, please let me know. In the meantime, feel free to play around a bit with everything.

DiveZoom_20150328.zip

[JtD]

Two things I'd like to illustrate using this tool:

1) Heavy vs. Light:

Comparing a Fw190 at 3850kg with a Fw190 at 3350kg (low on fuel, ammo, oil), you can see that there's no significant difference. The light version has a slightly better initial acceleration, after which the heavier version catches up in a dive. In the pull out the heavy version start losing what it gained, and at the end of the climb both aircraft end up at pretty much the same speed and altitude.

 

2) 5g pull out vs. 3g pull out in identical aircraft

This is something where you may be able to improve your tactics - the pull out at the bottom of the dive can make quite a difference in the end. The absolute figures just show that there's indeed a difference in the flight path, and already show that the higher g pull out will result in a higher final altitude. Looking at the relative performance, this becomes more evident. The low g pull out maintains a higher speed, flies a longer distance, but loses more E and ends up at a lower altitude. Of course, the harder pull out being slower by then, and will stall first. Maybe that's not worth the altitude gained.

 

Well, anyway, feel free to fiddle with it as you like, can be interesting.

[GOAT-ACEOFACES]

In the selected case, it can be seen that the aircraft reach about 800 km/h in the dive, and fail to regain their original altitude (absolute figures sheet).

 

That is also what I found when I did this same sort of testing years ago using IL2..

 

Very few of the planes were able to regain their original (starting) altitude before reaching the pre-determined cut off speed..

 

Just a heads up..

 

There is a certain self proclaimed A&E/Pilot expert in this forum that will tell you testing is in error!

 

Due to the fact that the total mechanical energy is changing!

 

He 'feels' the TE equations must remain constant (flat line).. And if it does not remain constant..

 

It means your violating the 'conservation of energy law' and therefore creating and destroying energy!

 

Which is not true!

 

But allot of people who only took elementary physics classes think that is the case, because the majority of examples they typically teach in an elementary physic class is that of a closed system where they assume there is no friction.

 

So, brace yourself!

[JtD]

That is also what I found when I did this same sort of testing years ago using IL2..

 

Very few of the planes were able to regain their original (starting) altitude before reaching the pre-determined cut off speed..

Yes, unless they don't dive very far and climb at a rather shallow angle. To illustrate - in my first post I've send the Fw190A-3 and the Yak-1 through the same vertical manoeuvre - and the Fw190 has a slight edge. If we are now looking at a scenario most Fw190 pilots are more familiar with, it will also show a result most of them are familiar with.

 

The Fw190 is 1000m above a Yak-1, dives down on it, and as it is closing in, the cruising Yak responds, starts to dive away, an evades the Fw190's gun through a pull up the Fw190 can't follow due to the higher speed (both pull up at 5g in the scenario). The Yak then starts a slightly shallower climb at 50° instead of 60° of the Fw, and both end up at the same speed at the same time. Result: The Fw, which started with a 1000m advantage, now only has a 300m advantage left, even though the Yak is actually the inferior aircraft in the vertical, as illustrated in the opening post. And where people expect flaws in the physics, quite the opposite is true.

 

(From my experience, the Yak will do a quick turn before pulling up instead of a straight pull up, which will reduce the altitude gained, but it will still gain in relation to the Fw.)

[=EXPEND=Tripwire]

Thanks for spending your time to put this information up. Interesting to see.

[GOAT-ACEOFACES]

Yes, unless they don't dive very far and climb at a rather shallow angle.

 

The testing I did with the old IL-2 used this test method..

• START @ 10kft @230mph IAS
• Apply Full Throttle & WEP (if aval)
• Dive @ -35° pitch
• Wait until you pass through 5,000ft
• Perform Pull out @ 5g (overload)
• Climb @ 30° pitch
• Wait until IAS = ~110mph
• END

My test was based on a WWII field test that pitted a P51 against a ZERO. The test consisted of two types of tests. A level zoom climb and a dive than zoom climb. I found the later more interesting and therefore chose that method. The real world test did not provide much detail as to the dive and climbing angles, but it did make note of the initial speed and altitude and that the end of the test was determined by an arbitrary IAS of the P51.

 

As for my previous statement of "very few of the planes were able to regain their original (starting) altitude before reaching the pre-determined cut off speed". I went back and looked at my testing and realized my memory was a little off, most were able to regain their original (starting) altitude before reaching the pre-determined cut off speed, but very few of the planes were able to surpass their original altitude (reach a higher altitude), and even fewer we able to surpass their original altitude 'and' increase their energy state (TE=PE+KE).

 

My focus was on the 'classic' energy (read zoom) fighters of WWII.. I started off with the P-47 in that it has the reputation of being one of the classic energy fighters.. I than tested several other well known energy fighters, and as a sanity check, I tested a plane that was not known as a classic energy fighter, ie the A6M2.

 

After doing the zoom testing I realized I had allot of data and could now do some separation testing, where separation is the distance between two planes, and the real focus of the original WWII filed test of the P51 vs ZERO. I didn't want to do very possible combinations of plane vs plane, so, I used the P-47 as the baseline that I compared all the other planes too.

 

ZOOM

ZOOM_P-47D_1944.pdf

ZOOM_P-51D-20NA.pdf

ZOOM_A6M2.pdf

ZOOM_Fw-190D-9_Late.pdf

 

SEPARATION

SEPERATION_P-47D-10_VS_A6M2.pdf

SEPERATION_P-47D-10_VS_Fw-190D-9_Late.pdf

Edited March 28, 2015 by ACEOFACES

[=LD=dhyran]

hmmm

 

what about airfoil design, basic oswald number, classic calculation of lift drag etc, wingload

Engineering an airplane is a very complex process, there is no linear function, its all dynamic and highly intresting math! creating a good FM takes up to 200 hours, finetuning it another 100 hours minimum

i am sorry, but this is no help at all, it just feeds basic misleadied complains

Edited March 28, 2015 by =LD=dhyran

[GOAT-ACEOFACES]

hmmm

 

what about airfoil design, basic oswald number, classic calculation of lift drag etc, wingload

Engineering an airplane is a very complex process, there is no linear function, its all dynamic and highly intresting math! creating a good FM takes up to 200 hours, finetuning it another 100 hours minimum

i am sorry, but this is no help at all, it just feeds basic misleadied complains

dyyran..

 

You may want to re-read JtD's post, most notably the part where he clearly said..

 

Please keep in mind that any 20 year old flight sim has more accurate algorithms than this tool, don't use it to prove FM issues. It's merely for a better understanding.

Hope that helps!

[=LD=dhyran]

dyyran..

 

You may want to re-read JtD's post, most notably the part where he clearly said..

 

 

Hope that helps!

 

 

cc i read that, but you know how ppl are, they put some numbers in and read some real results out of it, so it would have been better not to post that tiny tool....

[GOAT-ACEOFACES]

cc i read that, but you know how ppl are, they put some numbers in and read some real results out of it, so it would have been better not to post that tiny tool....

Disagree 100%

 

There are all types of people at all different levels of understanding..

 

The tool JtD provided is for those who want to learn more..

 

That and JtD clearly listed it's limitations..

 

So if some ding batt tries to use it as proof of an error in the game, it will only highlight the ding batt's inability to read and understand the written word.

 

Put another way

 

IMHO we should NOT hesitate in posting something like this in fear of what some ding batt might do with it.

Edited March 28, 2015 by ACEOFACES

[JtD]

Thanks for spending your time to put this information up. Interesting to see.

You're welcome.

 

The testing I did with the old IL-2 used this test method....

I'd love to have some hard numbers output and the autopilot for BoS.

 

what about airfoil design, basic oswald number, classic calculation of lift drag etc, wingload

Engineering an airplane is a very complex process, there is no linear function, its all dynamic and highly intresting math! creating a good FM takes up to 200 hours, finetuning it another 100 hours minimum

Oswald coefficient: fixed 90%, lift drag: calculated, wing load: irrelevant. You know, it's open source and it's just a couple of lines in an Excel sheet. Which you can a) check to see what they do and b) change to make them as complex as you like. However, the tricky part is to simplify these complex physics to a degree where the intended purpose is sufficiently well served. I'm asking for a mere four input parameters that should be fairly easily available, and the tool already provides much more accurate figures than "I feel this should be so and so". I could be asking for the aircraft polar, and while making the calculation more accurate, it would also defeat the tools purpose, as it would be inaccessible to nearly everyone for nearly all aircraft..

i am sorry, but this is no help at all, it just feeds basic misleadied complains

It doesn't, there were plenty of mislead complaints on this forum already, most of which could have been avoided had the posters taken a look at the basic physics. But I'll be waiting for the first post that goes "BoS in wrong, the zoom climb is just 1200m where that Excel sheet someone posted says it should only be 1100m". Edited March 29, 2015 by JtD

[RydnDirty]

In the real world the Fw190 with it's heavier construction can reasonably keep diving till IAS exceed 800km/h . The Yak has to throttle back or pull out as his IAS reach 700km/h.

 

The fact that the heavier plane can generally reach higher speed in the dive and carry more Kinetic energy into the zoom is a big part of why heavy fighters have a reputation for zoom climb.

 

In your chart you had Yak doing 756km/h which I highly doubt you or I would be willing to do in a real life 1942 Yak1 . The german pilots were known for regularly exceeding maximum allowed dive speeds . 

 

I wonder what it would look like if the Fw190 kept diving till he reach 850km/h which would be his equivalent to the yak1 reaching 750km/h.  Ke = half mass times velocity squared

So the fw190 is a heavier plane traveling faster into the climb. Ke is quadratic not linear

 

I just think you pushed the Yak to the limit but didn't push the Fw to it's limit.  If the Fw does his max speed in the dive there is no way the Yak can follow him back up. I have't flown BOS in a long time but this did work online a few patches ago. As long as I had the altitude to reach 800km/h IAS in a dive I could shake the Yak chasing me and end up out of gun range above him after he zoom.  

 

The zoom climb advantage comes from the top seed in a dive advantage. It is not just because heavy plane has more inertia and resist drag better in zoom. 

Edited July 21, 2015 by WillyZurmacht

[JtD]

If you want to have the Fw190 reach considerably higher speeds than the Yak-1, the Fw190 has to dive considerably further or considerably steeper than the Yak. In a chase, the Yak would certainly try to match the dive angle for as long as possible, so realistically the Fw190 can only dive further. If it dives further, it will lose energy in relation to the Yak and the zoom climb, starting at a lower altitude, will also end up at a lower altitude. The difference between reaching 750 and reaching 850 is about 1000m extra diving leading to a net loss of an extra 750m altitude after the zoom climb. In short, once you decide to dive away from an opponent, you'll stay below. I've provided the tool so you can check that for yourself in more detail.

Edited July 21, 2015 by JtD

[RydnDirty]

Of Course !  I didn't suggest other. If I am diving with a YAk chasing I would not stop diving till the YAk breaks off. That's the whole point of diving away from a yak.

 

If the Yak throttles back and tries to follow the Fw in the dive, which many will try to do,  then the FW will obviously have huge speed advantage when they both zoom climb, and  the Fw will end up safely out of range above a slow climbing yak. I have done this many many times online.

 

. If the Yak climbs when he approaches his top dive speed of 700IAS   and tries to anticipate the fw zoom climb, Then the FW pilot just extends away at 800km/h IAS. Either, way he no longer has a yak on him.

 

The Fw can out climb the yak from ground up at 500km/h IAS.   

 

I'm just trying to point out the the reason heavy powerful planes like FW190 and P47 have reputation for exceptional zoom climb is also very much related the the fact they have strong airframe and can achieve higher dive speeds than their opponents. It is not all about the extra inertia in the zoom climb. Which as you seem to be saying is not enough in itself.

[Dr_Molenbeek]

The Fw can out climb the yak from ground up at 500km/h IAS.

 

Yes, i did the test some weeks ago.

 

At 500km/h IAS constant as you say, the Fw 190A-3 (combat power) had needed about 30 seconds less than the Yak-1 to reach 1200m (from 200m).