Flight MH17 Downed By 'High-Energy Objects

originally posted by: _Del_

originally posted by: tanka418

No where near as "confused" as you think...

However, even after properly correcting for the air density, the wings still provide well over 32,000 pounds of lift at 35,000 feet. If we use a realistic coefficient of lift (something over 1) then it becomes rather easy for 35,000.

Sorry for the oversight.

Can you work an equation showing a Coefficient of lift at, say a healthy 1.0 for me/you (we'll keep the math simple)? I'd like to see your number and why you think it is well over 32000 lbf (you should probably stick to metric for the conversation, so that you don't have to keep converting back and forth for us).

Because my napkin number looks a lot less than that.

L = 1/2(pv^2) A Cl

L is lift force,
ρ is air density,
v is true airspeed,
A is planform area, and
Cl is the lift coefficient

So here it is...
air density at 35,000 feet (aprox): 0.00124 lb/ft2
air speed: 400 knots
wing area: 323 ft2
Cl: 1.5
(160000 * 0.0012) / 2 = 99.716; This is the pressure or lift per square foot on the wings.
99.716 * 323 = 32208.498 * 1.5 = 48312.74787 pounds of lift.

Probably doesn't agree with your guess, sorry...

a reply to: tanka418

you missed my point - as far as I can see you are not actually using the correct units - for example I am pretty sure "knots" is not the correct unit for speed.

and presumably your figure for density should be per foot^3, not squared (which is less important and a bit nit picking sorry )

Edit to add:

And of course if you do use consistent units (say the foot-pound-second) it generates pounds-force - and to determine the weight those can support you need to divide by gravity, which is about 32 ft/sec^2

originally posted by: Aloysius the Gaul
a reply to: tanka418

you missed my point - as far as I can see you are not actually using the correct units - for example I am pretty sure "knots" is not the correct unit for speed

No, no. Units don't matter. It's completely arbitrary. For instance, for velocity, I used 6.8640078256e-7 c. As you can imagine my lift force is quite a bit different lol

originally posted by: earthling42
a reply to: _Del_

Don't you think that airspeed is indicated in knots? that would mean a speed 926 km per hour, at this altitude it would probably stall if the speed is 500 km per hour.
The higher an aircraft goes, the higher the stall speed is.

Wrong! wrong! wrong! Stalls occur because of a supercritical angle of attack (or "alpha"), not because of some magical speed. My Sukhoi (yes, I own and fly one - a 31 - and have flown several of the models) will stall in level, power-off flight at about 105 kph IAS, depending on weight. When doing a down line snap roll at full power straight down, I stall it, to initiate the snap, at 250-280 kph IAS. The key is wing loading not speed. There has been all sorts of aerodynamic garbage posted in this thread. For example, a SU-25 has a 10.5% symmetrical (no camber) TsAGI (the Russian Central Aerodynamics and Hydrodynamics Institute) airfoil, which means that all aerodynamic lift derives from angle of attack and not speed influenced camber. Since at a higher altitude with its less dense air less lift is generated for a given alpha, alpha must increase to stay in the air. even higher altitude=even more alpha, until you exceed the critical number and earn a resulting exciting ride. Another problem is that the Soyuz/Gavrilov R-195 engines on the 25 do not have variable inlet guide vane technology so at high alpha there is a high risk of flaming out an engine. Instant "back side of the power curve" there. And with respect to speeding up to catch a Boeing, a symmetrical airfoil is very vulnerable to a phenomenon called "mach tuck." That results from the fact that as an an aircraft's speed increases, the aerodynamic center of lift of the wing moves rearward until, finally, the moment arm of the CG-CL axis exceeds the available downforce from the horizontal tail. A violent pitch down follows, usually resulting in airframe breakup and a big black smoking hole in the ground.

originally posted by: Aloysius the Gaul
a reply to: tanka418

you missed my point - as far as I can see you are not actually using the correct units - for example I am pretty sure "knots" is not the correct unit for speed.

and presumably your figure for density should be per foot^3, not squared (which is less important and a bit nit picking sorry

)

Edit to add:

And of course if you do use consistent units (say the foot-pound-second) it generates pounds-force - and to determine the weight those can support you need to divide by gravity, which is about 32 ft/sec^2

Actually density is in ft3, y bad, mis stated.

Velocity is expressed as "True Air Speed" which is measured in knots...or apparently from what I fund quickly...

Using gravity isn't necessary as all we need to do is product enough upward force (lift) to offset the mass of the aircraft. that whole gravity thing sort of happens all by itself...

Although, it would help my case IF we switched to MPH or something...bigger numbers.

a reply to: tanka418
Oh dear oh dear........yet again you miss the point - or at least 2 of them!!

1/ Yes airspeed is expressed in knots, but FORCE is NOT calculated in knots

2/ the downward "force" of the aircraft is its mass x gravity, and het upward force of lift you are calculating does need to take into account gravity - a 1lb force = 1 lb (mass) x acceleration(g), rearranging the formulate lb(m) = lb(f)/g

without understanding these you are not calculating anything.

originally posted by: Aloysius the Gaul
a reply to: tanka418
Oh dear oh dear........yet again you miss the point - or at least 2 of them!!

1/ Yes airspeed is expressed in knots, but FORCE is NOT calculated in knots

To be extremely nit-picky, you could express the airspeed in knots, but we would have to measure the wing area in nautical miles squared, and we would end up with an expression of force would be lb/nautical miles/second/second. And of course to measure the force of gravitation we are trying to lift as mass (in this case in lbs, I guess) times the acceleration expressed in knots, which is .0053nautical miles/s^2.
But otherwise, easy, peasy... Or you could treat all units as completely interchangeable and arbitrary. Whichever.

a reply to: _Del_

lol - yes, very good

a reply to: kdyam
a reply to: Zaphod58
a reply to: parad0x122
a reply to: da pickles

No.

I'm referring to Shrapnel rounds.

Shrapnel vs Shell Fragments
Henry Shrapnel

originally posted by: Aloysius the Gaul
a reply to: tanka418
Oh dear oh dear........yet again you miss the point - or at least 2 of them!!

1/ Yes airspeed is expressed in knots, but FORCE is NOT calculated in knots

2/ the downward "force" of the aircraft is its mass x gravity, and het upward force of lift you are calculating does need to take into account gravity - a 1lb force = 1 lb (mass) x acceleration(g), rearranging the formulate lb(m) = lb(f)/g

without understanding these you are not calculating anything.

Just as I knew would happen...
Okay, we done...as long as you don't wish to use real physics there is no point here. course there was no point all along, just some yahoos who over reacted to an irrelevant remark.

Anyway, I suppose you deserve the opportunity to defend your position; so, IF you have any real science to back up your "gravity" thing now would be a good time to post it...

originally posted by: watchitburn
a reply to: kdyam
a reply to: Zaphod58
a reply to: parad0x122
a reply to: da pickles

No.

I'm referring to Shrapnel rounds.

Shrapnel vs Shell Fragments
Henry Shrapnel

They are the same thing... I have always known them as flak rounds.. shrapnel works too.

Sayings like "don't give me any flak"or "i don't want to catch any flak

Items such as the "flak" jacket and such

although shrapnel could be interchangeable in any of the above terms or uses and means the same thing.

Thanks!

a reply to: tanka418

Just as I knew would happen...
Okay, we done...as long as you don't wish to use real physics there is no point here. course there was no point all along, just some yahoos who over reacted to an irrelevant remark.

Me thinks someone got in over their head and is now taking his deflated ball and going home.

Anyway, I suppose you deserve the opportunity to defend your position; so, IF you have any real science to back up your "gravity" thing now would be a good time to post it...

They did and you didn't understand it, and your gravity thing shows the science you prefer...3rd grade at best.

originally posted by: tanka418


Just as I knew would happen...
Okay, we done...as long as you don't wish to use real physics there is no point here.

Hey it's your formula.....

Anyway, I suppose you deserve the opportunity to defend your position; so, IF you have any real science to back up your "gravity" thing now would be a good time to post it...

Such as the definition of pound-force?

1lbf = 1lbm x gn
=1lbm x 32.174049 ft/s^2
=32.174049 (ft.lbm)/s^2

a reply to: tanka418

I have followed this, not contributing since aerodynamics is not a specialty of mine and the only knowledge I have is basic and from ground school from years and years ago.

But this... well.

Anyway, I suppose you deserve the opportunity to defend your position; so, IF you have any real science to back up your "gravity" thing now would be a good time to post it...

Really? Really?

My mind has just been blown... seriously.

a reply to: Aloysius the Gaul

Sorry y'all...but you are dead wrong.

I have shown the lift generated by the wing, and it is sufficient (even IF just), and all you can do to try to save face is distort the reality with detail that has little to no bearing...it's called obfuscation....shame n y'all!

Here's how this works. the weight of an SU-25 is on the order of 32,000 lbs. That's 32000 pounds pushing down on the aircraft. Oh, by the way; that weight? The product of the craft's mass and gravity...your "pound force".

The calculated "lift" is a pressure pushing UP on the wing...when the force pushing up is greater than the force pushing down, the object goes up...


It is rather apparent that none of the 4 of you have the required education to discuss the science here, yet you insist that you are correct...

Perhaps you should ask a high school physics teacher...

@bbracken677: perhaps you should stay out of a discussion where you have no knowledge. So...yes...absolutely...I demand to see their science!...and I want to see it backed up by someone with more education than me...

originally posted by: tanka418
a reply to: Aloysius the Gaul
Perhaps you should ask a high school physics teacher...

Perhaps you could ask one about what happens when we multiply or divide using different units...

a reply to: tanka418

So, what are your credentials that qualifies you in this debate?

I have ground school and flying time under my belt.

I also have a degree and post graduate in geology, which includes quite a bit of college level physics.

Do you really want me to jump in on this also? I can comment with clarity, succinctly and surety regarding using mixed units of measurements.

I could care less how high the plane in question can fly, cause I can tell you that the 777 most assuredly was not shot down with cannon fire. Any guessing that is what happened is ignorant to the nth degree. Guessing is all it is, backed by not a shred of evidence. If that is the point of this discussion regarding the aircraft in question then ... damn. Take off the tin foil hat.

originally posted by: bbracken677
a reply to: tanka418

So, what are your credentials that qualifies you in this debate?

I have ground school and flying time under my belt.

I also have a degree and post graduate in geology, which includes quite a bit of college level physics.

Do you really want me to jump in on this also? I can comment with clarity, succinctly and surety regarding using mixed units of measurements.

I could care less how high the plane in question can fly, cause I can tell you that the 777 most assuredly was not shot down with cannon fire. Any guessing that is what happened is ignorant to the nth degree. Guessing is all it is, backed by not a shred of evidence. If that is the point of this discussion regarding the aircraft in question then ... damn. Take off the tin foil hat.

I to am a pilot, though not able to fly due to cardiac issues.
Qualifications: MSEE, MSCS, several lesser degrees in physics, mathematics, chemistry...
As a software architect I have designed and deployed simulation software.

On the "mixed units"; that has already been addressed, and corrected; so...if that is all you got, let us drop this absurdity.

No one is saying anything about cannon fire...the signature of the damage ruled that out long ago. I brought up an item from a Greek news report about SU-25's in the area, and that they might have "forced" the 777 off course, and into harm's way. Every one else over reacted t that...I just point out that the SU-25 could have indeed done that.

Now y'all are trying to change physics just to support your own incorrect notions.

a reply to: tanka418

So just for the sake if argument, say you're right about the Su-25, and it can go that high.

You're saying that a Frogfoot flew so close to MH17 that they had to change course into the war zone (which their flight oath on FR24 shows no evidence of), and no one said a word about it on the radio? Not the pilots, not ATC, no one? Really?

a reply to: Zaphod58

You're saying that a Frogfoot flew so close to MH17 that they had to change course into the war zone (which their flight oath on FR24 shows no evidence of), and no one said a word about it on the radio? Not the pilots, not ATC, no one? Really?

And no radar return on this magical SU 25 except from the Russian military...supposedly.

And I would think that would have been a big concern for ATC to see a combat aircraft approaching this airliner, and they just said nothing about it.