Climb is not dependant on lift.

[bunch]

not sure, but i dont think induced drag exists in ground effect

[bunch]

Spitfire Mk.IX-400ER - the one with winglets - was kick bellybutton in dog fights

[gwshaw]

Both accel and climb are purely about PsubS, excess power. The only influence lift has on either is the induced drag, and the change in induced drag as the aircraft accelerates.

The equations are even similar:

Accel(fps) = xThrust(lbs) / Slugs (weight(lbs)/32.2)

Climb(fpm) = 33000/weight(lbs) * xHP

(By definition 1 HP lifts one lb 33,000 ft in one minute. That is where the 33,000 comes from)

Note that one equation is in xHp and the other in xThrust, so you will have to convert between units to solve them. But the end result is that climb and accel are both purely PsubS. Whoever has the best climb rate at any fixed speed will have the best accel at the same fixed speed, and vice versa.

But as HoHun has pointed out the situation is dynamic, not static. As the aircraft accelerates the induced drag decreases, pressure drag increases and P% changes. All of those factors are to the Fw 190A's advantage in a drag race from say 150 mph IAS vs a Spitfire V. The Spitfire's drag curves will cross about 160 mph, the Fw's about 180 mph or so. So while the Spitfire's total drag will start to increase about 160 mph, the Fw's will continue decreasing to about 180 mph. The Fw will retain the advantage of lower total drag all the way to vMax.

Even more important is P%, the Fw 190A appears to have had mediocre P% at climb speeds. When I have calculated it previously it tends to come out around 73-75%, compared to 80-82% for Spitfires, while both probably max at about 85% at high speeds. So as the Fw 190 accelerates its P% goes up, which translates into more excess power and better acceleration.

There is really no contradiction between a Spitfire V being able to outclimb a Fw 190A at climb speeds, and the Fw 190A being able to out accelerate the Spitfire V over time. The Spitfire V would have an initial advantage, but that would swing further and further in the Fw 190's favor as speed increased.

Greg Shaw

[Nashwan]

Originally posted by HoHun
Nashwan's comment on the relative speeds seem reasonable - if you're interested, I could try and graph relative acceleration for a set of assumptions about both planes' performance.

If the offer's still open, I'd like to see the graph.

Isegrim/Kurfurst still doesn't accept that climb and acceleration are proportional at any particular speed/altitude, and I think the graph would help clarify.

(It was a rather inaccurate graph of mine along the same lines, with hypothetical data, and the comment "The left colum shows climb rate, but could equally show acceleration, because climb rate and acceleration at any particular speed are directly proportional." that sparked the discussion in the first place)

[FUNKED1]

Nashwan, don't waste your time, this guy has absolutely no idea what he is talking about.  Page after page of gobbledygook.

[Glasses]

.....And a special appearance by the friendly neighborhood forum four eyes

[spitfiremkv]

climb is dependent on "excess power"
excess power is the difference between available power and the power required to keep the airplane flying  level.
that varies with airspeed, because drag also varies with airspeed.
there's an airspeed where you get the lowest drag, and that means you spend the least amount of power from your engine to maintain level flight, which means you have the most power to climb. you get best rate of climb at that airspeed.






now what happens at different airspeeds?
as you increase airspeed, parasite drag increases(simply put more friction between air and the airplane because more air molecules get in the way at high speeds) . At the same time, induced drag (the drag that accompanies any wing that produces lift), decreases with airspeed.
As you lower the airpseed, the exact opposite happens. More power is needed just to keep the airplane flying, because you are now flying slow, the wing has to develop more lift (hence you have to increase the AOA), and induced drag increases.(hey, your lift vector is now pointing sort of up AND backwards!). Also, induced drag is not entirely dependednt on AOA. A wing designed to produde a lot of lift will also  produce a high downwash, effectively simulating a wing at high AOA.

see here for explanations

http://www.grc.nasa.gov/WWW/K-12/airplane/induced.html

[Kurfürst]

Originally posted by Nashwan
Isegrim/Kurfurst still doesn't accept that climb and acceleration are proportional at any particular speed/altitude, and I think the graph would help clarify.

That`s like saying Nashwan still doesn`t accept the Holocaust did happened. It`s a strawman arguement from Nashwan, the like we got used to from him. Strawman arguements and manipulating others comments is the thing you know it is a Nashwan Post.

Personally, I do not need Nashwan to put words into my mouth. Yet, he does that on both forums.

Ie. his claims there about my position :

"Isegrim posted a thread on the AH board questioning whether climb and accelerated are proportional, as I claimed."

He is lying there, as I asked in my first post :


" 'Climb is not dependant on lift.'
I have just read that. First I thought I misread it.
Is it true ? "

That`s something completely different.  I am getting bored with the tricks Nashwan uses in every discussion.

What Nashwan is playing on both boards in selectively qouting peole and switching his and distorts his opponents position.


Originally Nashwan claimed two things :

a, that climb is not dependant on lift.

This was proven wrong as we all agreed that lift DOES depend on lift, as lift effects the excess power. So Nashwan was wrong.

b, Nashwan claimed the Spitfire should outaccelerate the FW 190.

This was again proven wrong by GWshaw.
(Nashwan qouted Shaw at ubi, but he did it selectively. He cut off the part in which gwshaw made it clear that the 190 will outaccelerate the Spit at most airpseeds except near-climbing speeds. Nashwan cut off that part of that qoute, as it proved his claim wrong, and represented it in it`s incomplete form).

"...But as HoHun has pointed out the situation is dynamic, not static. As the aircraft accelerates the induced drag decreases, pressure drag increases and P% changes. All of those factors are to the Fw 190A's advantage in a drag race from say 150 mph IAS vs a Spitfire V. The Spitfire's drag curves will cross about 160 mph, the Fw's about 180 mph or so. So while the Spitfire's total drag will start to increase about 160 mph, the Fw's will continue decreasing to about 180 mph. The Fw will retain the advantage of lower total drag all the way to vMax.

Even more important is P%, the Fw 190A appears to have had mediocre P% at climb speeds. When I have calculated it previously it tends to come out around 73-75%, compared to 80-82% for Spitfires, while both probably max at about 85% at high speeds. So as the Fw 190 accelerates its P% goes up, which translates into more excess power and better acceleration.

There is really no contradiction between a Spitfire V being able to outclimb a Fw 190A at climb speeds, and the Fw 190A being able to out accelerate the Spitfire V over time. The Spitfire V would have an initial advantage, but that would swing further and further in the Fw 190's favor as speed increased.


So in the end Nashwan was wrong in both of his claims. Now he puts up an partisanfight, and puts words into my mouth I did not say.

Because he does that repeatedly, let me clarify my position :

a, Climb is also dependant on lift, lift being a factor that determines remaining excess power on different aircrafts.

b, Nashwan was wrong and unable to support his claim that the Spit would be able to outaccelerate the FW 190 to as high airspeed as 300mph.



I have to ask Nashwan this : You still don`t accept that climb is also dependant on lift ?

[Nashwan]

Funked, I've had quite a bit of prior experience of Isegrim/Kurfurst on quite a few boards, so I know what to expect. (Physics isn't his strong point, which is obvious not just from this topic but his previous claim that when net thrust (inc acceleration due to gravity) and drag are equal, a plane will be stationary, rather than maintaining whatever speed it is at)

He is lying there, as I asked in my first post :


" 'Climb is not dependant on lift.'
I have just read that. First I thought I misread it.
Is it true ? "

That`s something completely different. I am getting bored with the tricks Nashwan uses in every discussion.

What Nashwan is playing on both boards in selectively qouting peole and switching his and distorts his opponents position.

No Isegrim that's what you first asked here, which isn't the gist of the argument on the UBI boards.

You're first post there was:

   Originally posted by hop2002:
    The left colum shows climb rate, but could equally show acceleration, because climb rate and acceleration at any particular speed are directly proportional.

    Simply, the better climbing plane accelerates faster at climb speed, the faster plane accelerates faster at high speed.

---------------------------------------------------


That`s absolute nonsense, made up by Hop who`s newest aganda seems to be to propagate that his beloved Spitfire does everything, in this case, acceleration than any other plane... a claim completely unsupported by any factual data.

Now the claimed proportional relation between climb speed and acceleration... completely silly. It seems Hop just doesn`t get climb is dependent on LIFT by a large margin. A simply example, make the Spitfire a biplane. It has now twice the wing area with massively higher rate of climb because of the lift area that doubled... would acceleration also double? Of course not, why would it, there is only extra drag and weight on the plane...

Look at actual examples, the Fiat Cr 42s were not known to be particularly fast, but with their biplane design, they easily matched the climb rate of the early Spits/109s even with much weaker engines.

That was on the 10th May. Today you went back and edited it to remove the first paragraph (the straw man attack)

You started this argument by claiming that increasing the lift would increase climb rate and reduce acceleration, and all the comments on this thread have said the opposite.

Originally Nashwan claimed two things :

a, that climb is not dependant on lift.

No, that's not what I claimed originally.

Here was my first post, that drew the response from you above:

   Pingu, Oldman, and myself tested the Bf-109G-6 Late, FW190A-8 and Spitfire VIII today. More will come from those tests but we did some acceleration (right from standstill) and found the 109 accelerated best from the start, with the FW190 in close second, then the VIII gains and overtakes...with the 109 close behind and the FW190 in the dust. Eventually the 190 passed us in a level speed run....so it does appear that its acceleration is behind that of the Spitfire and 109...more testing required.

--------------------------------------------------

I don't see much wrong with that, apart from the Fw190 doing well from standstill (although even that's possible. You were on the ground to begin with? If so, it eliminates induced drag, which would be worst of all on the 190)

Around climb speed (150 - 200 mph) the 109 and Spit should be doing much better than the 190, the 190 should begin to gain an advantage as the speed gets higher.

Here's a simple graph to illustrate the point:
(Image removed from quote.)
(It's not supposed to be accurate, just illustrate the general principle. The drop in climb/acceleration with speed is not linear, but not that far off either)

The left colum shows climb rate, but could equally show acceleration, because climb rate and acceleration at any particular speed are directly proportional.

Simply, the better climbing plane accelerates faster at climb speed, the faster plane accelerates faster at high speed. Somewhere the points cross, and that depends on both the climb rate advantage and the speed advantage (of course, if the better climbing plane is also faster, the points don't cross, and it accelerates faster at all speeds (above climb speed anyway).

Note that all this is altitude dependant, as both climb rate and speed vary with altitude, so will acceleration. For example, the Spitfire IX climbs better than the 190 at almost (all?) altitudes, but is slower at most. However, at some alts the Spit is both faster and better climbing, so you need to work out figures for any particular altitude.

That was my original claim.

The comment about climb not being dependant on lift was later on, in the following context:

Originally posted by Kurfurst:
It seems Hop just doesn`t get climb is dependent on LIFT by a large margin.

-----------------------------------------------------

Climb is not dependant on lift.

Well, no more than level flight is.

Lift causes induced drag, and that has an effect on excess thrust, but the effect is exactly the same in climb or level flight.

In a normal climb, lift = weight, exactly the same as in level flight.

Planes climb because they increase their attitude (point the nose up), not because lift is pushing them up.

That's my actual position, not what you are trying to present.

This was proven wrong as we all agreed that lift DOES depend on lift, as lift effects the excess power. So Nashwan was wrong.

That's exactly what I said in the first place, although it seems your grasp of physics doesn't allow you to understand the argument.

b, Nashwan claimed the Spitfire should outaccelerate the FW 190.
b, Nashwan claimed the Spitfire should outaccelerate the FW 190.

This was again proven wrong by GWshaw.

I was talking about the Spitfire LF IX, gwshaw about the Spit V, but we both agreeded on the principle that the Spitfire should accelerate better at low speed, the 190 better at high speed.

It should be obvious even to you that the Spitfire LF IX will do better against the 190, and shift the speed at which the 190 wins higher.

Originally posted by Kurfurst:
Because he does that repeatedly, let me clarify my position :

a, Climb is also dependant on lift, lift being a factor that determines remaining excess power on different aircrafts.

Only that was not your initial claim, and was mine.

Your initial claim:

Originally posted by Kurfurst:
It seems Hop just doesn`t get climb is dependent on LIFT by a large margin. A simply example, make the Spitfire a biplane. It has now twice the wing area with massively higher rate of climb because of the lift area that doubled... would acceleration also double? Of course not, why would it, there is only extra drag and weight on the plane...

My initial claim:

The left colum shows climb rate, but could equally show acceleration, because climb rate and acceleration at any particular speed are directly proportional.

My second claim in clarification:

Climb is not dependant on lift.

Well, no more than level flight is.

Lift causes induced drag, and that has an effect on excess thrust, but the effect is exactly the same in climb or level flight.

For anyone who wants to see the original argument:
http://forums.ubi.com/eve/ubb.x/a/tpc/f/63110913/m/7701003813/p/2

Isegrim's first response is at the bottom of page 3, my response to that p 4.

[Angus]

uHUMMM, Izzy/Barbi/Curfew....:
"That`s like saying Nashwan still doesn`t accept the Holocaust did happened. It`s a strawman arguement from Nashwan, the like we got used to from him. Strawman arguements and manipulating others comments is the thing you know it is a Nashwan Post. "

I know this from yourself, in the form of selective data and clipped quotes. Anyway, enough on that.

Ok, here is a straw for the both of you:

a) Climb does depend on lift as well as power
b) With enough power (thrust) no lift other is needed. Like a rocket!
c) Acceleration at a given speed holds hands with climb at the same speed, exactly like HoHun put it.

So what's all the squabble!

[hitech]

Angus:

a) Climb does depend on lift as well as power

Would normaly be considered false.

There have been discusion that climb is dependent on drag, And discussions that changing wing sizes can change a planes drag profile. But for any given wieght that a plane flys. The lift is always the same in steady state flight. Making the wing larger or smaller does not change the fact that in level or steady state climb the wing on any  plane of the same weight is producing exactly the same amout of lift (no mater how that wing is shaped).


Therefore you can not increase LIFT and make a plane climb better. You can only decrease drag or increase thrust to make a plane climb better.

HiTech

[gripen]

Well, maybe it should be noted that required lift (of the wing) reduce when the steady climb angle increase. The extreme case is a straight steady climb vertically when wing does produce no lift at all. That of course means that there is more thrust available than the weight of the plane.

gripen

[Angus]

Oh, HiTech:
"Therefore you can not increase LIFT and make a plane climb better. You can only decrease drag or increase thrust to make a plane climb better. "

Ehmm, I'm not getting this, for certainly, you can decrease lift for the same given power, same airframe, by i.e. clipping the wings if you see what I mean.
So, power + wings = climb rate right?
Wings do not lift alone of course, you always need thrust, and with enough thrust, you do not need another source to create lift.

Or am I lost here?

[gripen]

Angus,
The required lift (of the wing) in the steady climb depends on the weight of the plane and the angle of the climb. Decreasing the wing area means just that same lift must be produced with less area (assuming that the weight of the plane stays constant).

And yes, you are lost here

gripen

[Holden McGroin]

in 1986, Robert R. Harris climbed to an absolute altitude record of 14,938 m using no power at all after a low altitude tow plane release.

The motion of an aircraft is based upon the imbalance of four vectors.  Lift, weight, thrust and drag.  Change one and the other three seek equalibrium.   The only one we have direct control over is thrust, but Robert Harris climed to over nine miles high with no engine power at all.  So the requirement for thrust is somewhat negotiable.