Best Climb Speed Con't for Nashwan

[Crumpp]

Nashwan,


It's spelled out in black and white here:

http://www.av8n.com/how/htm/energy.html

Read about the physics and forces of climbing here:

http://www.av8n.com/how/


Nobody is saying that the Spit Mk IX did not have a faster climb rate. That is a fact.

Let me explain it ONE MORE TIME and PLEASE READ THE SCIENCE!

If we all flew gliders you could all understand this. Nobody is used to watching a “total energy variometer”, if we had TE Variometers this would make perfect sense to you.

The Spit does have a much slower best climb speed. That is a fact. The FW-190A8's best climb speed is around 182 mph. The Spit IX LF is 170 at best dropping quickly with altitude.

At a shallower angle and faster speed the than the spit the FW-190 reaches it's "rent free" zone in a sustained climb. If a spit points it's nose DIRECTLY at the FW-190 it will be out climbed because it cannot maintain the same VSI at the same AOA. It has to climb at a different AoA to get the same VSI.

If the spit cannot add any more power to the climb then he will pay the price in Airspeed. The TOP of the any A/C's power curve IS its best climb speed. That means the Spit wants to be going 170mph in the climb! The point where the maximum angle of climb and the top of the power curve meet is the best climb rate! Because the power curve is flat at the top, he will quickly find himself climbing at a shallower angle at 170mph.

So we have no gun solution and at the same VSI and the FW-190 is moving faster along the same vector. The spit gets out climbed.

Only way to reach the same VSI and angle is that both A/C are at the same point on the power curve. This would occur in a bounce when the FW-190 is climb at 1.32ata (climb and combat power) and the Spit comes in at full boost underneath it.

The ONLY way a Spit will be out climbed by an FW-190 is if he points his directly at the 190 and tries to follow him up.

If the Spit driver immediately goes for his best climb angle and speed he will readily out climb the 190.

Excellent example of how thrust effects climb:




quote:
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From one of those links Crummp likes us to see.
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Fw190A-8 (4300kg) / Spitfire JL165

2400rpm, 1.32 ata

6km - 9.1min
7km - 11.4min
8km - 14.4min

2700rpm, 1.42 ata

6km - 7.5min / 4.97min, +17.1lb
7km - 9.2min / 6.0min, +13lb
8km - 11.4min / 7.2min, +8.6lb

2700rpm, 1.58/1.65 ata

6km - 6.8min
7km - 8.6min
8km - 10.7min

When the FW-190 received more thrust it's angle of climb increased BUT it's Best climb speed stayed the same.

Check out the spitfires best climb speeds:

Spit V Merlin XLV - 170mph IAS - 6,450lb TO wt

http://www.fourthfightergroup.com/eagles/x4922.html

Spit V Merlin 45 (+16) - 170mph IAS- 6,945lb TO wt

http://www.fourthfightergroup.com/eagles/aa878.html

Spit Mk IX Merlin 66 (+25) - 170mph IAS 7400 lbs TO wt.

http://www.fourthfightergroup.com/eagles/jl165.html

Crumpp

[fats]

--- Crumpp ---
FW-190 it will be out climbed because it cannot maintain the same VSI at the same AOA. It has to climb at a different AoA to get the same VSI.
--- end ---

By AOA you mean the Angle Of Attack? Angle Of Attack refers to the angle of the wing compared to the velocity vector. I think you meant the climb angle?


// fats

[Crumpp]

http://www.av8n.com/how/htm/aoa.html#fig-incidence

Yep.  "Angle of climb" is the correct term.

We continued the discussion in another thread.

Crumpp

[Angus]

12 miles an hour is not MUCH.
Now a well boosted spitty could then, at its slower speed of climbing still add the same distance on a vertical level, - around 11 miles speed UPWARDS.
How is that possible?

[bozon]

crump.
AoA is irrelevant to any "outclimbing" question. it's not a geometrical variable to the relative position of the planes and even doesn't mean anything about where the nose is pointing on different planes - you can build a plane who will be with nose 10 degrees above the horison at AoA=0.

that website you keep linking, gives nice data that is useless to a pilot. Although what pilots actually control is the AoA they fly by IAS and throttle and for a good reason. that's because Nobody cares about AoA - it's some parameter "inside" the machine and does not describe the motion of the entire body.

if the angle of climb (speed vector over the horison) is "a" than pretty much (using you notation):
sin a = VSI / TAS (leaving out small instrumental corrections).

get the rate of sustained climb for each plane at the given speed => get "a" and compare.

The way to use climb angle in a fight is when you are already slow and slightly above the plane with shallower climb angle. If you both start climbing as steep as you can and you started above his sttepest line of climb he will pass under you and forward even if he has a better climb rate.

This is one explanation to Spit V "helicopter" properties people complain about. It just can climb steep.

Bozon

[Crumpp]

that website you keep linking, gives nice data that is useless to a pilot. Although what pilots actually control is the AoA they fly by IAS and throttle and for a good reason. that's because Nobody cares about AoA - it's some parameter "inside" the machine and does not describe the motion of the entire body.

It's written by a pilot for pilots bozon.  They guys is a certified FAA instructor and a PhD.  It's VERY important you understand Angle of Attack as a pilot.

AoA is irrelevant to any "outclimbing" question. it's not a geometrical variable to the relative position of the planes and even doesn't mean anything about where the nose is pointing on different planes - you can build a plane who will be with nose 10 degrees above the horison at AoA=0.

Your talking about angle of incidence here.  Totally different subject.

http://www.av8n.com/how/htm/aoa.html#fig-incidence

get the rate of sustained climb for each plane at the given speed => get "a" and compare.

1.  For a sustained climb
2.  Top of the sustained climb power curve is THE BEST CLIMB SPEED.

3.  First part of the climb is the zoom.  Zoom climb is a function of mass/Drag.  The Spitfire does not have much in the mass department and it's drag is unremarkable.  It's a poor zoomer.

This is a repost Angus and was intended to move the discussion out of the Spit V thread.  It didn't happen so I will repost the answer here:

Ok,

There seems to be some confusion as to what are A/C "numbers" mean.

Here:



quote:
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Suppose we wish to achieve the best rate of climb:

A) You could try to control the airplane by reference to the “rate of climb” number shown on the vertical speed indicator. This is not recommended!
B) It would be better to maintain VY, the nominal best-rate-of-climb speed, as shown on the airspeed indicator, and accept whatever rate of climb results. This is almost exactly the right idea.
C) It would be even better to realize that the best rate of climb is achieved at a particular angle of attack. In particular, if the airplane is lightly loaded compared to what was anticipated in the handbook, the best rate of climb will be achieved at a lower speed than is reflected in the handbook’s VY value.
This is not an isolated example. Many of the airplane’s critical performance numbers are really angle of attack numbers:
Þ The stall occurs at a particular angle of attack.
Þ The smallest power-off descent rate occurs at a particular angle of attack.
Þ The best power-off glide ratio occurs at a particular angle of attack.
Þ The recommended “approach speed” is really an angle of attack recommendation.
Þ The best rate of climb occurs at a particular angle of attack.
Þ The best angle of climb occurs at a particular angle of attack.1, 2
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http://www.av8n.com/how/htm/aoa.html

An Airplane achieves it's best performance when flown by it's numbers. It makes sense to non-pilots that "Power plus attitude = performance" but that is not the case.

Lets examine the power curve:


quote:
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Life would be simpler if manufacturers would explicitly show the power curve somewhere in the POH, but they don’t. You have to figure it out for yourself. Fortunately, the general shape of the power curve is more-or-less9 the same for all airplanes, so the concepts discussed here are very widely applicable.
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http://www.av8n.com/how/htm/energy....r-curve-regimes

That means all Airplanes have a FLAT power curve. The TOP of that curve is the BEST CLIMB Speed:


quote:
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Let’s start by comparing figure 7.5 to figure 7.6. As shown in figure 7.5, the highest point on the power curve represents the best rate of climb. The corresponding airspeed is denoted VY.
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http://www.av8n.com/how/htm/power.h...est-angle-climb

Not lets look at BEST CLIMB ANGLE:


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We see that the power curve is rather flat on top. That means that if you fly a couple of knots faster than VY, your rate of climb will hardly be affected at all. You will reach your destination a percent or two sooner, so this sort of “cruise climb” is generally a sensible thing to do.
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http://www.av8n.com/how/htm/power.h...est-angle-climb


quote:
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But don’t get carried away; the power curve tells you that if you slow down enough, you will degrade the climb performance to the point where further reductions in airspeed don’t pay.
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Both A/C can do this and the 190 is faster.

Since the top of the Power Curve is flat there is a wide variety of angles the plane can fly that have No effect on Airspeed. Your still going 170 mph at a shallower angle.

Now any climb which is started ABOVE Best Climb speed is a ZOOM CLIMB which ends, provided the Angle of attack is not ABOVE best climb angle in a sustained climb at Best Climbing speed. That is the point of equilibrium the plane wants to be at to balance the forces of flight.

If the 190A and a Spit begin a climb at the same speed:

1. In the initial zoom the 190 will leave the spit.

a. The 190 has more mass
b. The 190 has less drag

2. At the end of the zoom, both A/C will slow to Best Climb Speed.

a. The 190's Best climb speed is faster
b. IF the spit maintains the 190's shallower angle he will be left behind.


Crumpp

[Crumpp]

Nashwan, bro.

I am not trying to sound like an arrogant know it all, so please don't think I am in this reply.




quote:
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No, the excess speed will only drop off if you keep the angle high enough. Any plane can climb at any speed up to it's maximum speed, because at anything less than maximum speed it still has excess power.
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Look at the Power Curve again and see what happens as soon as you raise the angle of attack above Zero.
The speed begins to drop. When your zoom climb is finished, your plane drops to sustained climb speed. Your speed will balance out along that power curve. Angle for angle the 190 is faster. The end of the power curve is level flight.

But ONLY at angles below the 190's Best Climb angle.


quote:
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Obviously, at maximum speed climb rate will be zero, as all the available power is going to maintain forward momentum, and none is available to climb.
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Yes because the end of the power curve is level flight.


quote:
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Note that this graph assumes a linear fall off of climb rate with speed, which I doubt is accurate. Someone like HoHun, GWShaw etc would probably be able to do a much better job.
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Not sure exactly what you are showing with this chart, bro. If you are trying to say the Spitfire had a large enough angle advantage it could directly follow the spit it did not. It seems that way but when you understand the physics it could not catch it just because it's angle was better by following it directly.

I will say though the light bulb came on with this. I am not about to say that at high altitudes where the Spitfire performs its best and the 190 it's worst, that a Spitfire could not directly follow a 190. As long as the 190's best climb speed is faster. When it becomes the same then the Spitfire can directly follow.
Here is what the angle advantage will get the Spitfire:


quote:
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Otherwise, the Spitfire would always be able to outclimb behind, level out and catch the 190 while still climbing.
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Angus, bro, that is exactly what will happen IF the spit pilot abandons the direct chase and goes for his best angle of climb.
At that point a smart 190 pilot will level out and gain speed.
The Spitfire will end up above the 190 with more horizontal separation.


quote:
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You can climb at 300 mph at sea level in the Spit, just at a very shallow angle. You can hold a 300 mph climb in the Spit all the way up to 30,000ft or more. (TAS)
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And the reverse is true for the 190. Remember that degree of angle FOR degree of angle the 190 moves closer to its rent free zone in the shallow climb than the Spitfire. The Spitfires angle is steeper but is power curve height is much lower.


quote:
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You are adjusting the climb angle to keep a desired speed.
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Only until your angle reaches the top of the power curve which is flat. From there you have a wide range of angle that produce little change in airspeed.


quote:
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But if the Spit has a large initial advantage, it can afford to climb at less than optimum speed and still be better than the 190.
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The Spit has a large climb advantage but due to his lower best climb speed he cannot point his nose directly at the 190.
If he does the 190 will soon be above him. The Spitfire pilot has to point his nose up and use his greater climb angle advantage to out climb the 190.


quote:
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Try climbing in AH without using auto climb. Watch the ASI, and try to keep 170 IAS. You puch the stick forward when the speed drops below 170, pull back when it goes above 170.
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As it should. Your moving along the power band AND your on the "mushing" end of the curve so speed increases are more dramatic.


http://www.av8n.com/how/htm/power.html#fig-vx

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After this we can discuss why the spitfire would not be able to get a gun solution in the climb without totally mushing his zoom.

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quote:
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Nashwan, IMHO, at some alt bands, only the best Merlin spits could compete with the 190's on any level (190 outrolling always). The death and dread being the IX LF and VIII with 25+ boost.
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Looking at the power/weight increases of both types I don't think the Spitfire Mk IX (+25) would be much different from the FW-190A3 vs Spitfire Merlin 61 (+12) tactical trials.


quote:
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 There was nothing to choose between either aircraft as regards turning circles at any height; whether on offensive or defensive manoeuvres neither could make any impression on the other. In rate of roll, however, the Spitfire IX was considerably better especially at low altitude. A number of full rolls through 360 degrees were timed by the same pilot flying each aircraft in turn and although quanitative tests are difficult to produce, it appeared that there was often more than 1.5 seconds superiority for the Mark IX over the Mark VIII. The Mark VIII feels fairly light on the ailerons but at high speeds it becomes very heavy, and so this new combination of extended wing and small aileron cannot be considered satisfactory.
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http://www.fourthfightergroup.com/eagles/spit8tac.html

At altitude the Spit VIII would be nightmare but it's roll rate would severely hamper it.

Now the Spit XII clipped wing would be a tough fight for the 190 or for that matter any clipped wing spit would go along way towards reducing the 190's odds. Wonder how the turning circle of the clipped wings is effected.



quote:
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I think FW190 series development was very very poor during the war. Spits and did much better.
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Actually, that is a myth, if you study both series the FW-190A gained less weight and just as much power over it's lifecycle as the Merlin Spits.
Remember the Luftwaffe had it's own enemy test flight. The BMW-801 was "de-rated" while had a huge performance advantage. It increased in power/weight just enough to keep its traditional advantages. And like the Spit it received a much better armament package over it's lifecycle. Both the Merlin 66 (+25) and the BMW 801D2 (1.58ata/1.65ata) are 2000hp (+) motors. In fact they are almost exactly equal in power, just as the FW-190A3 and the Merlin 61(+12) Spit IX were in 1942.

Just as the RAF abandoned development of the Merlin Spits in favour of the Spit XIV, the Luftwaffe abandoned development of the 190A in favour of the Dora.

Now this only applies to jagd-einsatz's. The FW-190A became the Luftwaffe's "jeep" of the air. Comparing a jabo-einsatz's or a R7/R8 "Sturmjager" is apples and oranges to the Spit.

Crumpp

[Angus]

Crumpp.
My guess is that when the 190's had bounced enemy aircraft and escaped in their shallow climb, only to return again, they were already much faster, and the shallow climb performed at perhaps the range between 400 down to 250 mph.
12 mph speed difference in a climb takes very much too long to get you out of trouble.
And it isn't 12 miles anyway, that's just the difference between the most favourable climb speeds.
I'll try to get the time to get this to Newtons, but anyway, nice mindbogglers here.

[Crumpp]

Angus,

What I am saying is easy to see with the graph bro.

http://www.av8n.com/how/htm/power.html#fig-vx


The 190's Power curve and the Spits power curve will look very similiar to this curve.

Only difference is to raise the curve for the difference in Best climb speed.  You can then draw any angle from the center and where the angle of climb intersects the power curve you can then judge the speed difference.  It will not be strictly accurate but it is enough to know that at any angle below the 190's best climb angle the spit cannot follow it.  The shallower the angle the greater the speed difference.

12 mph speed difference in a climb takes very much too long to get you out of trouble.
And it isn't 12 miles anyway, that's just the difference between the most favourable climb speeds.

Remember too, the gap will widen at the difference in climb speed AFTER the zoom climb.  Meaning the 190 will have a good head start.

Remember the throttle adjustments move the entire curve up and down the graph.

http://www.av8n.com/how/htm/power.html#fig-vld

http://www.av8n.com/how/htm/power.html#fig-vy

It's a brain teaser for sure.  It certainly does explain why everyone just didn't build really light high lift fighters in WWII.

Crumpp

[bozon]

Crumpp, I give up on you.

Bozon

[justin_g]

Heres a rough set of "power curves" I graphed for the Fw 190A-5 and Spitfire LF.IX - I used Aces High to get the climbrates at different speeds and then raised the Spitfire curve to match the increased power/climb from the Merlin 66(Since AH Spit F.IX has Merlin 61).

[Crumpp]

Heres a rough set of "power curves" I graphed for the Fw 190A-5 and Spitfire LF.IX - I used Aces High to get the climbrates at different speeds and then raised the Spitfire curve to match the increased power/climb from the Merlin 66(Since AH Spit F.IX has Merlin 61).

Thanks for the effort you put into that graph.  The Spits and 190's in Ah have the same Best Climb Speed.  It still illustrates the point though.

Crumpp

[justin_g]

Hmm, point is that if you draw a line representing a certain climb angle, that climb angle is achieved when it intersects the power curve - as you can see the Spitfire LF.IX would be able to follow the same angle as a Fw190 at its optimum and it would be catching up(higher VSI and IAS)!

Edit: On the graph shown, in fact any climb angle over about 4.5º would enable the Spitfire to follow the Fw 190 along the same vector and catch it.

However this is only for SUSTAINED climbs - says nothing about zoom climbs.

[Crumpp]

Hmm, point is that if you draw a line representing a certain climb angle, that climb angle is achieved when it intersects the power curve - as you can see the Spitfire LF.IX would be able to follow the same angle as a Fw190 at its optimum and it would be catching up(higher VSI and IAS)!

Yes in AH they can.  And at low angles below the FW-190's best climb angle the FW-190 can get away in a climb.  Just not that quickly right now.  Again though the Best Climb Speed of the 190 is off in AH. It is exactly the same as the Spitfires.  Pyro is going to redo the FW-190's flight model here in the future.    


HTC is very busy with other things right now.  I for one am looking forward to TOD.

Crumpp

[GODO]

justin, if we set the best climb speed for 190A5 to 182mph instead of 170, shifting the 190 curve to the right and compressing it, the result is that 190A5 will outclimb and outrun the Spit LF at 252 mph, while still doing 2790 fpm.