Zoom Climb (1 Viewer)

[GregP]

Hello GregP,
Of all the people in this discussion, you and Shortround6 are the two that I would have expected the least argument for this line of thought.
The point I keep trying to make is that Mass is in both the PE and KE equations and therefore cancel each other out.
A WW2 aircraft flying to a hammerhead stall isn't behaving a whole lot different than the Streak Eagle.

Let's consider THIS situation:
We have two identical P-47 Thunderbolts.
One has a full load of fuel and ammunition. The other has no ammunition and much less fuel.
Figure one is 1500 pounds heavier than the other.
Both pull into a zoom climb at same angle and from the same initial level speed.
Which one will go higher?
Why?

Yes, one will have a bit more induced drag, but..... The additional weight should give it an advantage.
What do you really think?

Mass only cancels out if the masses of two different aircraft are nearly equal. If they are substantially different, then the masses make a big difference.

 

[Ivan1GFP]

Mass only cancels out if the masses of two different aircraft are nearly equal. If they are substantially different, then the masses make a big difference.

You are still not understanding. We are not talking about TWO different aircraft.
We are talking about ONE aircraft with a lot of KE in level flight and converting that KE into PE for altitude.
It is the SAME aircraft, so mass doesn't change except for a small amount of fuel burned during the zoom.

 

[pbehn]

You CAN quote the laws of physics pretty much until you get close to relativistic speeds and we are certainly not there in regards to any know aircraft or even spacecraft. They don't really chance much as we might want them to sometimes.
Everything else affecting a zoom climb is "part of the discussion". I was pointing out that weight canceled itself out as far as KE to PE conversion. The difference had to be aerodynamic effects such as streamlining and the relative effects of air on the vehicle, thus the mention of Reynolds number as a possible factor in the calculation.

You can put as much weight as you like into Fokker Tri plane and it doesnt affect the maximum speed in a dive because the wings come off. The Hurricane with fabric and dope wings was heavier than one with metal wings but the maximum dive speed was lower, because the fabric started to balloon and tear.

 

[Thumpalumpacus]

Sounds like you need more buzz practice!

I had enough of that in my misspent youth.

 

[Thumpalumpacus]

You CAN quote the laws of physics pretty much until you get close to relativistic speeds and we are certainly not there in regards to any know aircraft or even spacecraft. They don't really chance much as we might want them to sometimes.
Everything else affecting a zoom climb is "part of the discussion". I was pointing out that weight canceled itself out as far as KE to PE conversion. The difference had to be aerodynamic effects such as streamlining and the relative effects of air on the vehicle, thus the mention of Reynolds number as a possible factor in the calculation.

Doesn't mass retain inertia better?

 

[GregP]

You are still not understanding. We are not talking about TWO different aircraft.
We are talking about ONE aircraft with a lot of KE in level flight and converting that KE into PE for altitude.
It is the SAME aircraft, so mass doesn't change except for a small amount of fuel burned during the zoom.

How can it be the SAME aircraft? We've been talking about zoom climb comparisons. If you only have one airplane, then it can't zoom climb better or worse than itself. It can only climb better or worse versus some other airplane that almost certainly doesn't mass the same.

If you compare, for instance, a P-40N versus a Spitfire V, then the P-40N will be about 8,500 pounds and the Spitfire V will be about 6,300 pounds. The P-40 is about 35% heavier and thus, at the same altitude and speed, has about 35% more PE and about 35% more KE since ET = mgh + 1/2 m V^2; and g, h, and V are the same, leaving only mass as the difference. One airplane has only itself to compare with. It doesn't make sense to be talking about only one airplane and put the word "comparison" in the sentence. Compare implies more than one choice.

If you have a P-36 and P-40 loaded to the same weight, at the same height and velocity, producing the same power, then you can compare them. They will NOT zoom-climb the same.

 

[Ivan1GFP]

You can put as much weight as you like into Fokker Tri plane and it doesnt affect the maximum speed in a dive because the wings come off. The Hurricane with fabric and dope wings was heavier than one with metal wings but the maximum dive speed was lower, because the fabric started to balloon and tear.

Hello PBehn,
We are discussing Zoom Climbs, not Terminal Velocity Dives.
We are starting off in Level Flight at some speed and trade off that speed for altitude which means we end up going only slower.
The question I was asking GregP was whether he thought an aircraft would zoom higher or faster if it had the SAME aerodynamics but just additional weight.

When we start talking about structural limitations of various airframes and when they fall apart in a dive, it becomes a whole different subject.

 

[Ivan1GFP]

Doesn't mass retain inertia better?

Absolutely!
Increased Mass retains Inertia better but it also gets pulled down harder by Gravity.
Funny thing is that the two balance out EXACTLY which is what a fellow named Galileo is supposed to have proved at the Tower of Pisa. That is why all objects fall at the same speed and acceleration with differences being the result of the relative effects of air resistance.

 

[Ivan1GFP]

How can it be the SAME aircraft? We've been talking about zoom climb comparisons. If you only have one airplane, then it can't zoom climb better or worse than itself. It can only climb better or worse versus some other airplane that almost certainly doesn't mass the same.

If you compare, for instance, a P-40N versus a Spitfire V, then the P-40N will be about 8,500 pounds and the Spitfire V will be about 6,300 pounds. The P-40 is about 35% heavier and thus, at the same altitude and speed, has about 35% more PE and about 35% more KE since ET = mgh + 1/2 m V^2; and g, h, and V are the same, leaving only mass as the difference. One airplane has only itself to compare with. It doesn't make sense to be talking about only one airplane and put the word "comparison" in the sentence. Compare implies more than one choice.

If you have a P-36 and P-40 loaded to the same weight, at the same height and velocity, producing the same power, then you can compare them. They will NOT zoom-climb the same.

Hello GregP,
This is getting frustrating.
Please go back and read post #20.
I know you quoted it but I don't think you actually read it.

Lets take your examples:
P-40N at 8500 pounds going 300 MPH - KE = (M * V^2) / 2
P-40N at 5000 feet altitude going 0 MPH - PE = M * G * H
Same aircraft. Same Mass. Mass is in both KE and PE equations. They cancel out when compared.

Spitfire at 6300 pounds going 300 MPH - KE = (M * V^2) / 2
Spitfire at 5000 feet altitude going 0 MPH - PE = M * G * H
Same aircraft. Same Mass. Mass is in both KE and PE equations. They cancel out when compared.

Since you apparently didn't like the Thunderbolt in earlier example, Lets use Corsairs this time.
Suppose we have two identical Corsairs. The only difference is that one has a full ammunition load and full fuel while the other has no ammunition and minimal fuel.
Both are at the same altitude and speed pull into Zoom climbs at the same angle.
Which will zoom faster or further and why?

 

[pbehn]

Hello PBehn,
We are discussing Zoom Climbs, not Terminal Velocity Dives.
We are starting off in Level Flight at some speed and trade off that speed for altitude which means we end up going only slower.
The question I was asking GregP was whether he thought an aircraft would zoom higher or faster if it had the SAME aerodynamics but just additional weight.

When we start talking about structural limitations of various airframes and when they fall apart in a dive, it becomes a whole different subject.

You cannot have the same aerodynamics, whatever weight you have needs to be lifted, that lift is provided by the wings, to change from level flight you need to increase the AoA to provide that lift and climb, to climb with more weight needs more lift. I associate zoom climb to be a climb rate from a speed not attainable in level flight as in "boom and zoom" tactics, obviously you dont, could you please clarify the difference between "zoom climb" and "maximum climb rate" in your thinking.

 

[pbehn]

Hello GregP,
Of all the people in this discussion, you and Shortround6 are the two that I would have expected the least argument for this line of thought.
The point I keep trying to make is that Mass is in both the PE and KE equations and therefore cancel each other out.
A WW2 aircraft flying to a hammerhead stall isn't behaving a whole lot different than the Streak Eagle.

Let's consider THIS situation:
We have two identical P-47 Thunderbolts.
One has a full load of fuel and ammunition. The other has no ammunition and much less fuel.
Figure one is 1500 pounds heavier than the other.
Both pull into a zoom climb at same angle and from the same initial level speed.
Which one will go higher?
Why?

Yes, one will have a bit more induced drag, but..... The additional weight should give it an advantage.
What do you really think?

Are you discussing it being easier to climb with more weight?