Author Topic: Best Climb Speed Con't for Nashwan (Read 12756 times)

Crumpp · « **Reply #90 on:** August 25, 2004, 07:12:14 PM »

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Did Priller say what speed he climbed away at? If not, why do you think it was 182mph and not 275mph or 300mph?

Oh I am sure he was down on the lower end of the power curve climbing at a really shallow angle.

Crumpp · « **Reply #91 on:** August 25, 2004, 07:23:31 PM »

It's sent off, Hopefully to the right address!

Crumpp

GODO · « **Reply #92 on:** August 25, 2004, 07:45:52 PM »

Not 100% related to the topic, but very interesting link about P47 vs 190 (june 43), being the P47 a good performer at alt. Look at the results at 26000 feet. May be 190 (probably A5) was not so bad performer and climber at hi alts.

190 vs P47

There is also an interesting comment about weights:

"The Fw.190 was loaded as a fighter to 8300 lbs., and the Thunderbolt to 13140 lbs."

niknak · « **Reply #93 on:** August 25, 2004, 08:29:25 PM »

I'll admit to not having read the whole thread but things seem to have got over complicated (i could be wrong, i could be over simplifying).

I imagine 2 cyclists. One is a heavy bodybuilder with strong legs, one is a regular cyclist who weighs less. On the flat the bodybuilder's sheer power allows him to pedal faster than the cyclist. However only a small amount faster not in proportion to the weight difference (the cyclists muscles are just for cycling he has no extra baggage).

In a simple model we have the foward force (a constant of how hard these guys can cycle) and a parasitic drag which determines the max speed of the cyclists.

If we cycle up an incline we have an extra "drag" the component of weight parrallel to the direction of travel. At a given angle each of the cyclists net forward force will decrease compared to the "flat" force. The steeper the incline the more weight is a factor i.e. the the bodybuilders net forward force will fall quicker.

It follows at shallow angles (i.e. following the same trajectory) the bodybuilder will pull away as he still has a top speed advantage. However as the trajectory increases the cylcist will match then exceed the bodybuilders velocity. i.e. anything above this critical point given the same trajectory the cyclist will catch the bodybuilder.

what is more the cyclist will be able to climb steeper as the net force will take longer to go to zero. This is akin to assuming identical stall speeds, power curves etc.

In summary : given an angle past the "critical point" the spit will catch the 190 wheather it is at best climb speed or not.

Question is at what angle is the critical angle?

Crumpp · « **Reply #94 on:** August 25, 2004, 08:35:55 PM »

You got it.

Good illustration.

Crumpp

Karnak · « **Reply #95 on:** August 25, 2004, 08:56:30 PM »

Crump,

I got it, but cannot open powerpoint files on my home system.

niknak,

That is the question. It seems to me like it should be somewhere around 250mph to 260mph.

justin_g · « **Reply #96 on:** August 25, 2004, 09:18:37 PM »

Yup - around 250mph would seem to be a reasonable figure for the intersection of the Fw 190A-5 and Spitfire LF.IX power curves.

Which would mean that(even if both planes are flying on the SAME angle of climb):
below 250mph = Spitfire outclimbs Fw 190
above 250mph = Fw 190 outclimbs Spitfire

Karnak · « **Reply #97 on:** August 25, 2004, 10:16:14 PM »

Crump's Graph:

justin_g · « **Reply #98 on:** August 25, 2004, 11:55:41 PM »

For power curves the vertical axis is meant to be climbrate - in which case the Spitfire is shown as having a lower maximum climbrate than the Fw 190! It should be at least 500fpm more.

Given the shape of those curves - if you moved the Spitfire curve up to represent it climbing at 4500fpm maximum - then the Spitfire curve would be above the Fw 190 curve until a speed very close to maximum level speed, maybe 300mph or so!

bozon · « **Reply #99 on:** August 26, 2004, 03:54:02 AM »

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Originally posted by GODO
Not 100% related to the topic, but very interesting link about P47 vs 190 (june 43), being the P47 a good performer at alt. Look at the results at 26000 feet. May be 190 (probably A5) was not so bad performer and climber at hi alts.

190 vs P47

Extra many thanks!

very interesting website, will keep me busy for a while.

for those interested, the main page is:
http://www.lanpartyworld.com/ww2/

Bozon

hitech · « **Reply #100 on:** August 26, 2004, 08:57:56 AM »

Crump: Your graph has a few problems.

First the label on the vertical axis should be labled climb rate. Climb angle would be the grey lines.

2nd the red and blue lines are not power curves. They could be viewed as exsess power (i.e. (thrust - drag) * vel ) , but all those lines are showing is climb rate to vel. If they realy are excess power curvs, then to compair climb rates each would have to be divided by the mass. In which case the FW cuvre would shift down relative to the spit fire and you could see that they would cross much farther to the right. I.E. like we have been saying in the 250 - 280 range.

Finaly it dosn't match the data we are discussing. We have been basing this discusion for the spit having a max climb rate of around 700 greater than the FW.

In that chart look at the highest point on both curvs (the top point is max climb rate). Notice that the FW shows having a higher max climb rate than the spit. Hence it might be they just need to be adjusted for the mass.

On a side note the far left of each line is the stall speeds of the aircraft's.

HiTech

Crumpp · « **Reply #101 on:** August 26, 2004, 12:25:25 PM »

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Finaly it dosn't match the data we are discussing. We have been basing this discusion for the spit having a max climb rate of around 700 greater than the FW.

Yes it does achieve a 700 foot a minute climb rate advantage. AT its BEST CLIMB SPEED and ANGLE.

FACT: BEST CLIMB RATE is achieved at a certain speed and ANGLE of Attack and it the point of equilibrium of forces on the Aircraft in a climb. In short, it is where the plane wants to be.

FACT:The Spitfires BEST CLIMB SPEED is 170mph. The BEST CLIMB SPEED is the TOP of the power curve.

FACT: The top of the Power curve is Flat, therefore it can fly at a wide variety of angles with LITTLE CHANGE to that speed. It can fly much faster than 170 mph BUT the speed changes occur at much shallower angles.

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If they realy are excess power curvs, then to compair climb rates each would have to be divided by the mass.

I think you are reading too much into it. They are only graphical representations of ACTUAL performance.

ACTUAL performance numbers of what the aircraft DOES in the air.

Begining of the Power curve = Level flight speed

Top of the power curve = best climb speed

Very end of the power curve = stall speed

You are factoring variables that are already accounted for in the actual performance of the plane by adding in mass again.

In order to outclimb the 190 on the same vector the spitfire would have to be traveling along that vector at a greater rate of speed. It physically cannot due to the fact top of it's curve is lower and the curves look the same.

IF the top level speed of the 190 was less than the spitfire then there would be a portion of the curve the spitfire could directly follow.

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In that chart look at the highest point on both curvs (the top point is max climb rate). Notice that the FW shows having a higher max climb rate than the spit. Hence it might be they just need to be adjusted for the mass.

It is not a representation of the climb rate just the climb angle. Now by adjusting the scale of the axis and the curves you could easily fit it into the acutal data.

Even then it works out that the 190 would leave a directly following spitfire behind.

Crumpp

bozon · « **Reply #102 on:** August 26, 2004, 12:41:36 PM »

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Yes it does achieve a 700 foot a minute climb rate advantage. AT its BEST CLIMB SPEED and ANGLE.

Crumpp, if your Y axis is indeed climbrate, (it's clearly isn't angle) than your spit and 190 have the same maximum climbrate.

also, what you draw as the best climb angle, hits the curve at the point of best climb rate.

Bozon

edited.

Karnak · « **Reply #103 on:** August 26, 2004, 12:43:29 PM »

Nobody has claimed that the Spitfire would outclimb the Fw190 at the same vector and same speed.

Your statements are contradictory.

1) The Spitfire has a higher maximum climb rate.

2) The Spitfire can climb faster at 182mph than the Fw190, even though 182mph is the Fw190's best climb speed and not the Spitfire's.

3) The Spitfire obtains it's superior climb rate by climbing at a steeper angle.

Now you have also claimed that the Spitfire can climb faster than the Fw190 at 182mph by steepening it's climb angle.

FACT: If the Spitfire has the power to steepen it's climb angle beyond the Fw190's best climb angle and maintain 182mph it has the power to go faster than 182mph at a shallower climb angle.

If the above is true the Spitfire should be able to simply reduce throttle and follow the Fw190 directly at 182mph.

If the above is not true then the Spitfire should have a top sea level speed of ~250mph as it is losing ~600fpm of climb rate for every 10mph gained in speed.

justin_g · « **Reply #104 on:** August 26, 2004, 01:16:24 PM »

The poor man, he's completely lost.