# Climb rate.



## starling (Jul 16, 2012)

Hey guys,it's me again.Forgive me if this question has been asked before(I did check the search box).
Before the jet and rocket aircraft had been developed ,which piston aircraft of ww2 had the fastest climb rate.? Thanks,starling.


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## tyrodtom (Jul 16, 2012)

I don't know if you can count the F8F Bearcat as a WW2 fighter, it was operational before the end of WW2, but never saw combat. It had a roc of 4600 ft per min., that's probably initial rate of climb. 
The late model Me 109K would probably be a close contender for the best.
The little CW-21 had a pretty high rate of climb too, if the figures stated for it can be believed.

Hopefully one of the board scholars will post some graphs, or more precise figures.


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## Shortround6 (Jul 16, 2012)

starling said:


> Hey guys,it's me again.Forgive me if this question has been asked before(I did check the search box).
> Before the jet and rocket aircraft had been developed ,which piston aircraft of ww2 had the fastest climb rate.? Thanks,starling.



Fastest for how long (or high)

Some planes could climb very well at sea level and for 1-3 minutes and then tended to "flame out".

Others started a bit slower but could maintain a good climb for a number of minutes.

A select few could both climb well at sea level and keep climbing well 5-10 minutes later. 

Do you want the fastest in FPM ( or meters per sec) at sea level or fastest to 10,000ft ( 3000 meters ) or 20,000ft (6,000) meters or???????

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## davebender (Jul 16, 2012)

Fw-187 probably had the fastest rate of climb during 1939 along with a level speed of 395mph. Makes me wonder how fast this lightweight aircraft would climb powered by a pair of 2,000 hp DB605D engines during 1945.


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## cimmex (Jul 16, 2012)

Do you think that you can stress a 2x1000hp airframe with 2x2000hp?
cimmex


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## davebender (Jul 16, 2012)

I'll let the engineers sort that out. 

Ju-88 and Me-210 airframes made the switch to heavier and more powerful DB603 engines so I wouldn't bet against a Fw-187 powered by DB605D engines.


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## krieghund (Jul 16, 2012)

What is the weight and power requirements? Combat weight, normal take-off weight? Maximum power, balls to the wall, ignore the time limits? Time from take-off or altitude to altitude without zoom effect?


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## davebender (Jul 16, 2012)

Most WWII aerial combat probably happened between 5,000 and 20,000 feet. So how about a climb from 10,000 to 15,000 feet?
- Normal combat weight. Full ammo load. 75% fuel remaining. No drop tank(s).
- War Emergency Power.
- Starting from level flight @ economical cruise speed of 275mph.


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## Jabberwocky (Jul 16, 2012)

starling said:


> Hey guys,it's me again.Forgive me if this question has been asked before(I did check the search box).
> Before the jet and rocket aircraft had been developed ,which piston aircraft of ww2 had the fastest climb rate.? Thanks,starling.



Spitfire, 109K and late P-63's were probably the kings of climb, although I don't have data for some of the late Soviet types, which would have been very spritely at lower altitudes. 

Spitfire Mk IX, fully armed, was tested at 5740 ft/min in October 1943, with the Merlin 66 running at 25 lbs boost on 150 octane fuel. Ran with rads closed. Service examples at 25 lbs boost were probably good for about 5100-5200 ft/min with rads open.

Spitfire Mk XIV was tested at 4850 ft min with the Griffon 65 at +18. Later examples were cleared for +21 boost, with estimated performance of about 5150 ft/min.

Bf-109K was calculated at 24.9 m/sec (4920 ft/min) with MW/50 and a DB 605 ASM at 1.98 ata

P-63A-10 was tested at 5000 ft min in 1944. 

Topping all these were very late piston aircraft such as the F8F, Hornet/Sea Hornet and Sea Fury, all of which made over 5000 ft/min in combat trim.


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## stona (Jul 17, 2012)

Jabberwocky said:


> Bf-109K was calculated at 24.9 m/sec (4920 ft/min) with MW/50 and a DB 605 ASM at 1.98 ata.



I'm glad that you said "calculated" 

Cheers
Steve


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## glennasher (Jul 20, 2012)

What about the P-38? It was designed as an interceptor originally, so I'd suspect it climbed at a good clip.


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## starling (Jul 25, 2012)

Hey guys,the fastest to,28.000 foot.Starling.


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## krieghund (Jul 25, 2012)

From take-off or in flight, weight power?


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## CobberKane (Jul 27, 2012)

One very important thing to consider when considering rate of climb is how fast the aircraft is moving forward as it moves upward. For instance, at the right altitude and speed a 1940 Zero could climb (briefly) at 5000 ft/min, about the same rate as a Spitfire XIV of 1944. The differrence is that the Spit would have been climbing at a more shallow angle from the horizontal, but matching the Zero's vertical velocity due to it's greater horizontal speed. Hence, if the Zero were on the tail of the Spitfire and both were at their optimum climbing speed, the Zero might have matched the Spit in vertical velocity but all the time the Spit would have been opening the gap between the two very quickly. Alternatively, if the Spit were on the Zero's tail, it would be climbing vertically at the same rate as the Zero but would overshoot it very quickly.
I've often thought this is a little understood consideration when considering the relative climb rates of fighters. It seems that generally the fighter that climbed with a greater forward speed had the advantage in that the pilot could dictate the terms of the fight. I'd be interested to hear from anyone more knowlegable on the subject.


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## davebender (Jul 27, 2012)

That's a specialized mission. We would need to consider Me-109 and Spitfire models powered by high altitude engines. Not the bulk of Me-109s and Spitfires which were designed for combat at lower altitudes.


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## FLYBOYJ (Jul 27, 2012)

CobberKane said:


> One very important thing to consider when considering rate of climb is how fast the aircraft is moving forward as it moves upward. For instance, at the right altitude and speed a 1940 Zero could climb (briefly) at 5000 ft/min, about the same rate as a Spitfire XIV of 1944. The differrence is that the Spit would have been climbing at a more shallow angle from the horizontal, but matching the Zero's vertical velocity due to it's greater horizontal speed. Hence, if the Zero were on the tail of the Spitfire and both were at their optimum climbing speed, the Zero might have matched the Spit in vertical velocity but all the time the Spit would have been opening the gap between the two very quickly. Alternatively, if the Spit were on the Zero's tail, it would be climbing vertically at the same rate as the Zero but would overshoot it very quickly.
> I've often thought this is a little understood consideration when considering the relative climb rates of fighters. It seems that generally the fighter that climbed with a greater forward speed had the advantage in that the pilot could dictate the terms of the fight. I'd be interested to hear from anyone more knowlegable on the subject.



Vx Vy


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## timmy (Jul 29, 2012)

*I just don't understand Climb rates Period ?*

Like if you give me specs on an aircraft.. Power/Weight/Aerodynamics I then have got a fair idea on whether that plane is going to be fast or slow

But if I do the same thing trying to Guess *Climb rates* I always seem to guess wrong. Now I know light weight is important for climb. 
As well as Big propellers and Big Engine capacity with torque help as well ..and with things like 2 stage superchargers I guess.

But if I read up on say one aircraft like a Tempest V ,weight 9000lb, 2100 hp against say a F4U-4 which also has weight 9000lb, 2100 hp and both have Big 4 blade propellers

You would then guess the climb rates would be the same ???? Wrong, most articles put the Tempest in the 5000ft /min mark against the F4U-4 4000ft/min 

So what gives ????


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## FLYBOYJ (Jul 29, 2012)

timmy said:


> *I just don't understand Climb rates Period ?*
> 
> Like if you give me specs on an aircraft.. Power/Weight/Aerodynamics I then have got a fair idea on whether that plane is going to be fast or slow
> 
> ...



Timmy, 
it's not as easy as you think. One has to consider the propeller/ engine / airframe combination as well as weight, let alone the basic aerodynamics of the aircraft's wing surface that will make it a good climber. A weather factor called density altitude plays in as well. All this for starters...

Google Vx and Vy and this will give you some basic information about climb as well...


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## Shortround6 (Jul 29, 2012)

timmy said:


> *I just don't understand Climb rates Period ?*
> 
> 
> 
> ...



Power available for climb ( power to weight ratio for climb????) is the power left over (surplus) after you take out the power _needed_ to fly level at the "best climb speed". best climb speed _for one aircraft_ is not the same as another. It is the speed at which the plane needs the _least_ amount of power to maintain level flight and this is _*NOT*_ stalling speed or just above. A wing will only give so much lift at a certain incidence ( angle of attack) and a certain speed. Lower the speed and the angle of attack _has to increase_ for level flight, but as the angle of attack goes up the drag goes up. Going too slow causes more drag than flying 20-50mph faster. but since the drag goes up with the square of the speed trying to climb while going fast in the forward direction doesn't work well either. 

The problem with trying to compare one aircraft to another with only basic data (weight, horsepower, etc) is you don't know the climb speeds or the drag at climb speed or the surplus power at climb speed. The Tempest is faster than the F4U-4 using the _same power_ at sea level, so we assume ( I KNOW, I KNOW) that it has less drag. This means when flying at the same speed it has more power available for climb. Without a lot more complicated calculations we don't know how much more. And we don't know if the climb speeds are the same or different.


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## FLYBOYJ (Jul 29, 2012)

Also read about "excess thrust"


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## davparlr (Jul 29, 2012)

Shortround6 said:


> but since the drag goes up with the square of the speed trying to climb while going fast in the forward direction doesn't work well either.


Lift also goes up with the square of the speed so increasing speed also provides as significant an increase in climb as it does drag. It seems to be a battle. If we take two aircraft with identical wings and therefore identical Cl and area, both have identical weight, and both have identical normal rated thrust, but airplane A is much dirtier than Aircraft B, and compare these two aircraft we find that Aircraft B can maintain a higher speed than aircraft A with the same power and same angle of attack. It is this increased of airspeed that translates into a faster horizontal velocity and more lift thus faster climb (vertical velocity) or as flyboyJ would say Vy and Vx which is the results of excess power of airplane B as SR6 stated. That's what I think! 

Basically, comparing climb performance based only on power, weight, and wing area leaves significant data out.


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## bentwings (Nov 13, 2021)

Shortround6 said:


> Fastest for how long (or high)
> 
> Some planes could climb very well at sea level and for 1-3 minutes and then tended to "flame out".
> 
> ...



im sure because of variables that militaries had some standard test means, but being a former top fuel and funny car racer . It seems to me that preparing for combat would be the purpose. Here. Say that each plane would be prepped for combat at the target altitude. Combat munitions, fuel and what ever was needed. Planes to be only prop planes for this test. We arrange them on a nice runway far enough apart so they won’t have accidents.. electronic beam across the runway, picked up the tires. Just like drag racing.. to complicate a little altimeters must be calibrated equally. must Be the same model. . Modify the dash hole as required but system must be the same. Stop determined by altitude . Electronically timed. We want to time each plane to compare so each breaks it’s own starting beam. We can drag race later. For now just who is fastest on record.

ready….. set. GREEN. Go! Kamikazes are coming. Elapsed time wins and is number one qualifier for the real race.

byron

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## GregP (Nov 15, 2021)

There is a very good basic formula for rate of climb. Not infallible, but pretty good for an estimate.

RC = 33000 * (PA - PR) / W, where PA = power available (hp). PR = power required for level flight, W = Weight (pounds). RC = rate of climb (feet per minute).

Take a Hawker Sea Fury. Normal specs for a Sea Fury FB.11 show: Gross Weight = 12,350 lbs. HP at sea level = 2,480. Known initial rate of climb = 4,320 fpm.

Solving using the formula allows us to solve for power required: PR = 863.2727 hp.

So, if we let the weight drop down to, say, 10,400 pounds, we can estimate a rate of climb at 5,130 fpm. At that weight, there isn't much fuel or ammunition left, so the sparkling performance won't last for long or do much good, other than to support the lifestyle and feeling of power of the pilot.

The Vought F4U-4 Corsair has almost the same specs. Gross weight as a fighter = 12,405 pounds. HP at sea level = 2,400. Known initial climb rate = 4,360 fpm.

Solving for power required gives = 761.0364 hp.

Again, if we let the weight drop to, say, 10,400 pounds, we expect a rate of climb of about 5,200 fpm. These two planes perform almost exactly the same, with very similar expected climb at very light weights.

Both planes only have these climb rates at war emergency power (2,400 hp or so), with the throttle breaking through the wire stop. At normal military power (1,500 hp or so), both are considerably less sprightly in climb. For both, I'd expect a cruise-climb at 2,000 - 2,200 fpm for most operations. Max rate of climb would be in the heat of combat, not normal flying.

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## GregP (Nov 15, 2021)

looking at my reply above, I apologize for missing the point!

The main reason there is so much disparity among reports of things like top speed and rate of climb is the almost complete lack of test data. It makes a difference, sometimes a BIG difference, what the test weight was, whether or not WER was used for the climb power stetting, and whether or not there were racks / rails fitted to the wings. It CAN make a difference whether or not the cowl flaps were open or shut. Most of the time, when we see an initial rate of climb quoted, the basic aircraft data for the test are not included in the text, and it makes a huge difference.

Most WWII fighters had three weights reported; empty weight, gross weight, and maximum takeoff weight. Standard aircraft characteristics are generally given at gross weight and military power. Sometimes they report using WER, but you have to check to find out. Whenever you see very high rates of climb, it is generally clean, no racks, WER and minimal weight. Think an empty airplane with maybe 1/3 fuel and half or no ammunition. That is NOT a good position for the pilot to be in if he is 200 miles from base and in a fight, but it makes the airplane look really good in a brief performance report. WER consumes fuel at a prodigious rate and low fuel is not what you need unless you are over your own home runway.

By way of example, retired AVG pilot Johnny Allison paid a visit to Joe Yancey's hangar while I was working there and talked about demonstrating the P-40 for Claire Chenault. He mentioned using 75" MAP for the demonstration and flying with half fuel, no ammunition, and no survival kit / extra anything inside. At the time, the maximum approved MAP was 47". Naturally, the P-40 put on a sparkling display. But most of the time, it didn't perform like that because it was being flown within approved limits and was loaded with fuel, ammunition and normal loadout items.

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## pbehn (Nov 15, 2021)

bentwings said:


> im sure because of variables that militaries had some standard test means, but being a former top fuel and funny car racer . It seems to me that preparing for combat would be the purpose. Here. Say that each plane would be prepped for combat at the target altitude. Combat munitions, fuel and what ever was needed. Planes to be only prop planes for this test. We arrange them on a nice runway far enough apart so they won’t have accidents.. electronic beam across the runway, picked up the tires. Just like drag racing.. to complicate a little altimeters must be calibrated equally. must Be the same model. . Modify the dash hole as required but system must be the same. Stop determined by altitude . Electronically timed. We want to time each plane to compare so each breaks it’s own starting beam. We can drag race later. For now just who is fastest on record.
> 
> ready….. set. GREEN. Go! Kamikazes are coming. Elapsed time wins and is number one qualifier for the real race.
> 
> byron


Another test would be to ring up a squadron at random and tell them an enemy bomber is circling at 18,000ft one mile to the south of their airfield. Stop the clock when 12 aircraft have formed up on the decoy. The difference between best and worst in WW2 was measured in fractions of an hour not minutes and seconds.

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## GregP (Nov 15, 2021)

Almost all of the surviving WWII fighters still flying are privately owned. The likelihood of the owners letting someone thrash their airplanes nd VERY expensive engines for such a test at WER is shockingly close to zero. There are a dearth of pilots qualified to thrash these airplanes as you describe and do it safely since most have never run gasoline higher than 100-Octane Low-Lead. Nobody will let you change is or her altimeter to make them all standard. You'd have to fit auxiliary altimeters. Many lightweight unit are available.

Alas, we pretty much have to reply on test conducted during WWII or while they were still in Military service.

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