Ok, new question, DRAG and WEIGHT.

[fscott]

K, here's a real world question. Suppose you take the propellors off all the planes in AH. Hold them by their tails pointed straight down. Let's start them off with a good average stall speed of say 100 mph. Now, you dropped them. Tell me which aircraft will accelerate the best?

I assume this is a mere test of drag/weight ratio. So I am interested in which plane drops like a rock the best. This is a real-world question that deals with B&Z, since it is a technique of flying I'm really starting to like -  with the propellor on of course.

fscott

[funked]

"I assume this is a mere test of drag/weight ratio"

Yes it is.

It's probably the P-47D.

However some number crunching is required to be certain, and I don't have enough data to do it.

Wells?  

[Zigrat]

my money is on pony


weight 70% of jug but has alot lower fpa than 70% of jug

[NHFoxtro]

I say the Pony as well.

[Dingy]

 

Originally posted by fscott:
K, here's a real world question. Suppose you take the propellors off all the planes in AH. Hold them by their tails pointed straight down. Let's start them off with a good average stall speed of say 100 mph. Now, you dropped them. Tell me which aircraft will accelerate the best?

I assume this is a mere test of drag/weight ratio. So I am interested in which plane drops like a rock the best. This is a real-world question that deals with B&Z, since it is a technique of flying I'm really starting to like -  with the propellor on of course.

fscott

Sparing you the physics behind all this, its not a weight issue but a drag issue pure and simple.

-Ding

[hitech]

In general the heavy planes but the difference at the starting 100mph will be very small the difference in acceleration will increase as the planes start moving faster. My guess is one of the buff's followed by the 47. Easy way to test is just do a 0 g push over on the planes at a low throttle but not cut throttle setting for 10 secs and see who ends up the fastest.

HiTech

[hitech]

Dingy you are incorect it's not just a drag issue, is a combination of drag and weight.

HiTech

[Dingy]

 

Originally posted by hitech:
Dingy you are incorect it's not just a drag issue, is a combination of drag and weight.

HiTech

How so?  You arguing with Galileo who proved that all objects fall (this is what the planes would be doing in an engine-off situation) at the same speed regardless of their weight?  Now when you get those items in a drag inducing environment, you can see why a feather and a bowling ball fall at different rates.  

Unless Im mistaken, the only force causing the plane to speed up in a free fall is gravity (calculated by F(grav) = Gm(1)m(2)/r^2).  The force of gravity will favor the slightly more massive plane albeit NEGLIGIBLY due to the HUGE mass of the Earth (6*10^24 kg).  Feel free to plug the numbers into that proven formula above and you'll see what I mean:

G = 6.67 * 10^-11
m(1) = mass of any plane ya choose....P51 is 5266 kg when loaded, B17 is 27,240 kg when loaded)
m(2) = mass of Earth, approx 6*10^24 kg
r = distance between the two masses in meters....doesnt matter whch value you choose.

When you talk about free fall in an atmosphere, the only force slowing the plane and working in opposition to gravity is drag .  Drag DOES NOT have a mass component to it and if it does, please show me what it is I am missing?

-Ding



[This message has been edited by Dingy (edited 01-30-2001).]

[AcId]

Dingy- I believe you practicaly answered your own question. We're not talking about a vacuum here, therefore I would think the weight would have some influence. I would tend to think that the heavier of 2 objects having the same drag coe would fall faster.

But then again I may be crazy.

[Dingy]

 

Originally posted by AcId:
Dingy- I believe you practicaly answered your own question. We're not talking about a vacuum here, therefore I would think the weight would have some influence. I would tend to think that the heavier of 2 objects having the same drag coe would fall faster.

Dunno maybe its me thats crazy but I've never seen weight figured in any airflow/drag calculations.

-Ding

[hitech]

Dingi attach your bolling ball to the feather, Obviously total drag of the new combined object has gone up from both the feather or the bolling ball, yet together they fall faster than just the feather. I.E. is a ratio of Drag and wieght.

HiTech

[Dingy]

 

Originally posted by hitech:
Dingi attach your bolling ball to the feather, Obviously total drag of the new combined object has gone up from both the feather or the bolling ball, yet together they fall faster than just the feather. I.E. is a ratio of Drag and wieght.

HiTech

HT, Im sorry but Im not sure what kind of point you are trying to make here.  We still have normal physics to deal with.  

IN A VACUUM, all objects fall at the same speed.

IN A DRAG INDUCING ATMOSPHERE, when an object is in free fall, the only forces acting on an object are a) gravity in a downward direction and b) drag in an upwards direction.  We've already shown (and I think you agree) that the mass of an object has negligible effect on the downward force of gravity but no one has been able to show that mass has an effect on either parasitic or induced drag.  You've been working on this longer than I have, show me how parasitic and induced drag is calculated.

-Ding

[This message has been edited by Dingy (edited 01-30-2001).]

[Jimdandy]

The weight is only a factor in wing loading. The drag is the biggest factor in the situation describe. In a vacuum a bowling ball and a feather fall at the same speed. It is wind drag that is that major player here. The terminal velocity is in direct proportion to the drag/frontal area of the aircraft. NO IF AND OR BUT'S! I say the P-51. The major reason the water cooled inline V engined plane were in vogue in WWII was FRONTAL AREA! Look at the level fight low alt speed of most of the WWII aircraft. Generally the inline V engined planes are the fastest at sea level.

[Dingy]

Heres a counterexample to yours HT, take a 16 lbs bowling ball and a 50 lbs parachute and attach them together.  When the parachute opens, the objects fall SLOWER than the bowling ball alone yet it weighs more than the bowling ball by itself.  LOL!

 

-Ding

[-towd_]

just a thought what are the terminal velocitys of the different aircraft in a unpowered state . seems to me that if one had a significantly higher terminal velocity and they were droped from a high altitude it would pretty much be the fastest in this situation. depending on how much the velocitys vairied from plane to plane . and would the terminal velocity decrease as the craft encountered the thicker atmosphere nearer to sea level ?  but my money is on the p47 twice the weight and not twice or anywhere near that amount drag ( unless im missin a geometric progression somwhere in drag/pressure ) and the terminal velocitys would be in the mach 2 plus ranges anyway right so all that would hit the ground would be the engine and alot of little pieces anyway. ( pw r2800 planes will be all about equal then )