Surprised to see Cliffs of Dover FMs very good considering the age

[Lusekofte]

Well I would probably be in your shoes if fighters was of any interest. I have or better say had issues with JU 87 and HE 111 This normally would be my favorite planes.

I hate them in this game, the Heineken feels like a helium Zeppelin and the Stuka constantly wanted to fly another way and felt very sluggish on the controls, I have been flying the Stuka lately, now it feels better. But it might be my new controls

But the IL 2 and PE 2 just is great,

I like the Lagg also, so it might just be that I am as picky as you, I just do not fly planes I do not like

Btw I am talking about BOS

[Sokol1]

Well, anyone that know CloD "release" and official patches history - fix this, broken that - know that Clod work and is enjoyable, but in "CloD way". 

 

TF 5.0 for example "fix" Br.20 top turret control for mouse users, but broken for joystick axis control - what are done perfectly, as this was powered turret... (several things in CloD is need understand how are done for make sense - not just expect a "iL-2:46" copy) but we know, users prefer a "gamey" way...

 

In some 100oct Spit version, the propeller don't stop spin after cut the fuel and magnets - in the ground - what prevent re-start the engine. "It's CloD".

 

CloD fix for perfectionists.

Edited August 27, 2016 by Sokol1

[Cloyd]

Very funny, Sokol1.

[taildraggernut]

totally off topic but I did not say zero G....

 

 I did, mainly because the transition from 1 g to any negative value involves passing through zero g

 

A windmilling propeller produces drag and lots of it......

 

The entire disc area essentially acts as a flat plate.

 

 

 A  propeller does not 'windmill' the instant a pushover is performed, the drag effect is not instant, but the reduction of induced drag from reduced lift is, therefore there will be a reduction in overall drag before the prop disc has a chance to catch up, you don't seem to have understood the first time I said this.

 

 

Power requirements roughly follow velocity cubed...

 Ok, so how much drag reduction is needed to gain 20mph?

 

The fuel injected engines never lost power and had a windmilling propeller..

 

Yes, and allowed the 'full' advantage of the reduced induced drag in a pushover.

[Crump]

I did, mainly because the transition from 1 g to any negative value involves passing through zero g

 

 

 

 A  propeller does not 'windmill' the instant a pushover is performed, the drag effect is not instant, but the reduction of induced drag from reduced lift is, therefore there will be a reduction in overall drag before the prop disc has a chance to catch up, you don't seem to have understood the first time I said this.

 

 

 

 Ok, so how much drag reduction is needed to gain 20mph?

 

 

 

Yes, and allowed the 'full' advantage of the reduced induced drag in a pushover.

There is no "reduction" of drag and then increase.

 

The moment power is reduced and rpm is constant....the propeller is windmilling. The drag force seeks equilibrium and moves to balance by slowing the aircraft down

 

The drag force increase is proportional to the power reduction. It is very substantial and quite frankly, the dominate drag force acting on the airplane. Think of it as an aerodynamic anchor and something MEI's are very familiar with. Watch that drag demo video I posted. Note the descent rate of the aircraft increases 100% with a windmilling propeller. The descent rate doubles compared to the propeller feathered.

 

You are correct that unloading the wing reduces drag due to lift. You would get a drag reduction at a constant power.

 

The actual power required math would required calculating the aerodynamic coefficients and forces under the specific conditions. I am in a crash pad right now about to start a 4 day in the am.

 

You can get a ballpark idea though just by using the physics relationships.

 

600 hp is required to fly at 150 Knots. How much horsepower does it take to fly at 170 knots?

 

Pr2 = Pr1(V2/V1)^3

 

Pr2 = 600(170/150)^3

 

Pr2 = 873hp or a 273hp increase to speed up 20 knots.

 

Yeah I know 20 knots is faster than 20mph but the point is it takes a lot of power to increase speed. That is just an illustration of the basic relationship. Keep in mind aircraft have speed stable and power stable region but in general.....a 20mph increase requires a substantial increase in power available to power required.

[Crump]

Well, anyone that know CloD "release" and official patches history - fix this, broken that - know that Clod work and is enjoyable, but in "CloD way". 

 

TF 5.0 for example "fix" Br.20 top turret control for mouse users, but broken for joystick axis control - what are done perfectly, as this was powered turret... (several things in CloD is need understand how are done for make sense - not just expect a "iL-2:46" copy) but we know, users prefer a "gamey" way...

 

In some 100oct Spit version, the propeller don't stop spin after cut the fuel and magnets - in the ground - what prevent re-start the engine. "It's CloD".

 CloD fix for perfectionists.

That is very funny. I am not trying to beat up CloD. It is just constructive criticism based on the few "wtf" moments I have had in it.

[Crump]

Well I would probably be in your shoes if fighters was of any interest. I have or better say had issues with JU 87 and HE 111 This normally would be my favorite planes.

I hate them in this game, the Heineken feels like a helium Zeppelin and the Stuka constantly wanted to fly another way and felt very sluggish on the controls, I have been flying the Stuka lately, now it feels better. But it might be my new controls

But the IL 2 and PE 2 just is great,

I like the Lagg also, so it might just be that I am as picky as you, I just do not fly planes I do not like

Btw I am talking about BOS

Lol.....I think you are as picky as me.

[ACG_KaiLae]

Crump, I think you should post on the team fusion section on the ATAG forum about this stuff. I'm not sure if the right people are listening here; it's basically the wrong forum.

[Uufflakke]

 I have or better say had issues with JU 87 and HE 111 This normally would be my favorite planes.

I hate them in this game, the Heineken feels like a helium Zeppelin and the Stuka constantly wanted to fly another way and felt very sluggish on the controls, I have been flying the Stuka lately, now it feels better. But it might be my new controls

 

 

Heineken?!?

Heinkel I suppose you wanted to say.

What's on a men's mind...

Well, after drinking too much Heineken you do feel like a helium Zeppelin indeed.

[Sokol1]

 I am not trying to beat up CloD.

 

But in the end this (grounded) criticism there only has effect to blacken more the poor CloD.

 

For good effect, if you have access to ATAG forum I may suggest post the issues in Team Fusion sub-forum, or in CLOD TF Bug Tracker.

 

http://tfbt.nuvturais.de/login?back_url=http%3A%2F%2Ftfbt.nuvturais.de%2F

[Lusekofte]

Heineken?!?

Heinkel I suppose you wanted to say.

What's on a men's mind...

Well, after drinking too much Heineken you do feel like a helium Zeppelin indeed.

I am in Crete, my wife has taken over my MacBook Air so I am stuck with my iPad mini and its autocorrect, it is not adapted to ww2 air warfare

[SvAF/F16_Goblin]

:drinks: I can live with Heineken, imagine if they made sims

https://www.youtube.com/watch?v=QghICtdvNH4

Edited August 28, 2016 by I./ZG1_Goblin

[taildraggernut]

There is no "reduction" of drag and then increase.

 

 

Actually there is, the instant the lift begins reducing by means of a pushover then the drag is reducing, the engine does not begin cutting the instant the pushover is made, let's face it, if the engine started cutting at 0.9 g then the aircraft would not be able to fly in even the mildest turbulence, it should even continue to produce power in the first fractions of negative g, I'm sure there will be some crackpot theories that Spitfires could not fly in turbulence soon enough though.

[Crump]

 

Actually there is, the instant the lift begins reducing by means of a pushover then the drag is reducing, the engine does not begin cutting the instant the pushover is made, let's face it, if the engine started cutting at 0.9 g then the aircraft would not be able to fly in even the mildest turbulence, it should even continue to produce power in the first fractions of negative g, I'm sure there will be some crackpot theories that Spitfires could not fly in turbulence soon enough though.

There is no decrease in drag that overcomes the windmilling effect of the propeller. Even when you reduce the power back on a CSP equipped aircraft, windmilling slows the aircraft dramatically. That is why a CSP equipped aircraft has such good speed control on approach compared to the same aircraft with a fixed pitch propeller.

 

 

Your turbulence analogy is a rabbit hole. .9 G turbulence is extremely uncomfortable and rare unless you make a habit of flying thru thunderstorms.

 

http://www.dtic.mil/dtic/tr/fulltext/u2/403365.pdf

[taildraggernut]

There is no decrease in drag that overcomes the windmilling effect of the propeller. Even when you reduce the power back on a CSP equipped aircraft, windmilling slows the aircraft dramatically. That is why a CSP equipped aircraft has such good speed control on approach compared to the same aircraft with a fixed pitch propeller.

 

 

Your turbulence analogy is a rabbit hole. .9 G turbulence is extremely uncomfortable and rare unless you make a habit of flying thru thunderstorms.

 

http://www.dtic.mil/dtic/tr/fulltext/u2/403365.pdf

 

There is no instant windmilling drag to overcome, there is your rabbit hole, the Merlin engine won't cut in a positive g range, it probably won't cut the very second a negative value is reached, so that's the drag reducing from 1g right down to 0g before the engine starts cutting.

 

if you ever go flying you will realise .9g is not so rare.

[Venturi]

if you ever go flying you will realise .9g is not so rare.

 

I was getting 0.5g from turbulence just flying over the Santa Monica mountains in the late afternoon in a Cessna 172.

[Lusekofte]

Heineken?!?

Heinkel I suppose you wanted to say.

What's on a men's mind...

Well, after drinking too much Heineken you do feel like a helium Zeppelin indeed.

 

[SvAF/F16_Goblin]

[Crump]

 

if you ever go flying you will realise .9g is not so rare.

Lol, the FAA limits me to 1000hrs per year....100 hrs per month...30 hrs in 7 consecutive days and 8 hrs in a 24hr period. If the company could get more....they certainly would!!!

 

Your turbulence is a rabbit hole because of exposure time and frequency. There is no need to speculate as I presented the measured data. You just have to read it!

 

Yes, .9G turbulence is extremely rare and very uncomfortable. Most assuredly, early merlins did sputter in turbulence. I have got several anecdotes that attest to that fact. However, to say they "couldn't fly" in any turbulence you as a human being would care to be exposed to is just not true. Turbulence of a frequency and exposure time that would caused excessive cut out....well the cut out would be the least of your worries.

[DD_Arthur]

I don't know how he manages it but every week... every day....he becomes more and more full  of it.

Edited August 30, 2016 by DD_Arthur

[Crump]

There is no instant windmilling drag to overcome, there is your rabbit hole, the Merlin engine won't cut in a positive g range, it probably won't cut the very second a negative value is reached, so that's the drag reducing from 1g right down to 0g before the engine starts cutting.

 

if you ever go flying you will realise .9g is not so rare.

 

Guess I have to give a lot of money back to my employer as I am being paid quite a good living to fly lots of people safely. In fact Iam restricted to 1000 hrs per year, 100 hrs per month, 30 hrs in 7 consecutive days, and 8 hrs in 24 hrs period. If the company could work me more....they certainly would!!

 

It is the fact turbulence has a very limited exposure time and high frequency that makes your theory a rabbit hole. So you would experience a 25 second -.9G acceleration exposure followed by a ,25 second +.9G exposure. It is not a series of single exposure for prolonged periods. I posted some measured data for you to read because I have experienced your participation in talks before.

 

Additionally, .9G turbulence is rare and extremely uncomfortable.

[ACG_Invictus]

 

LOL!

 

That picture was worth wading through the mounds of prattle.

 

Enjoy the FM wars.  I'm off to enjoy both sims for what they are.... warts and all.   

[Crump]

That is hilarious.

[Crump]

Very low — below 0.05g; light pitch, yaw and roll oscillations are experienced.

Low — 0.05 to 0.2g; aircraft might experience light to moderate 'chop', i.e. slight, rapid, rhythmic bumps and oscillations but any without significant changes in altitude or attitude. Like driving a boat through a choppy sea. Also known as 'cobblestoning' — like driving at moderate speed on a corrugated gravel road.

Moderate — 0.2 to 0.5g; turbulence is becoming significant and the ride produces strong, intermittent, uncomfortable jolts with attitude upsets and indicated airspeed variations, but the aircraft remains in control. The occupants' heads may hit the cockpit roof structure if the clearance is small or the harness is not tight enough.

Severe — 0.5 to 1.5g; the aircraft handling in all axes is made difficult but not dangerous except at lower alitudes — if occupants and objects properly secured.There are large, abrupt changes in altitude and attitude, and significant variations in indicated airspeed. Cockpit instruments are difficult to read.

Very severe — above 1.5g; the aircraft is violently tossed about, with extreme handling difficulty. Aircraft may be out of control for short periods. Structural damage is possible.

 

http://www.recreationalflying.com/tutorials/safety/wind_shear.html

 

.5 to .9 G is severe turbulence.....

 

Controlling an aircraft in severe turbulence is extremely difficult. I have experienced it once. The result was a duel compressor stall and an altitude loss of ~12000 feet before relight.

 

Scared the hell out of everyone onboard. If you have ever heard compressor stall, it sounds like the engines are going to explode in a series of rapid, very loud bangs.

[Crump]

http://maps.avnwx.com/help/turb_desc.html

 

It usually causes large variations in indicated airspeed. Aircraft may be momentarily out of control. Report as Severe Turbulence.

[taildraggernut]

I see where you are confused now, you think I meant a magnitude of .9g, which I did not mean at all but rather used .9g as a representation of under 1g at the beginning of a pushover where induced drag would reduce by equal magnitude, or in other words a reduction by .1g which is very much light turbulence.

My mistake was assuming you understood that.

 

So let's clear this up:

 

begin a pushover in a Spit and transition from 1g level flight down to 0g and the induced drag will reduce proportionally to zero at zero g, all this time the merlin engine will 'NOT' cut while still in a positive g range and is unlikely to cut the instant a negative value is reached. therefore drag reduces and power is still being produced and no props are windmilling.

[Crump]

It is very simple,  In a propeller airplane,  i the engine cuts out, the propeller windmills...

 

When the propeller windmills....lots of drag is produced and the aircraft slows down.

 

 

In CLoD....the airplane speeds up.  That is not correct.  End of Story.  No rabbit holes required.

[taildraggernut]

in level flight maybe but not in a dive.

 

end of story

[Crump]

 

 

in level flight maybe but not in a dive.

 

Yep...even in a dive.  Again, if you fly a constant speed propeller aircraft, the windmilling propeller is one of the properties that gives you such excellent speed control on descent (final approach).

 

End of Story. 

[Crump]

http://www.vansairforce.com/community/archive/index.php?t-39323.html

[Crump]

You are flying along Taildraggernut and you have the propeller disc producing thrust.  In steady flight, it is producing the exact amount of thrust as the aircraft produces drag.

 

Windmilling the propeller is equal to not only stopping that propeller from creating thrust, you are turning all of it into drag production.  It is equal to putting a solid disc the same diameter as the propeller out in front of the airplane.

 

[xvii-Dietrich]

That viewgraph states that "The drag produced by a windmilling propeller is equal to the drag produced by a solid disc of the same radius"

 

That doesn't make sense to me.

• A solid disc has area pi-R^2
• A static propeller will have area less than this, as there are only blades which is a small fraction of the area.
• Any windmilling or slight angle of the blades will only serve to reduce the effective area even further.

[Crump]

It is not static...it is windmilling.  It is actually generating reverse thrust.  

 

 

 

 

The parasitic drag (including the 'reversed thrust') is greater than that of a stationary propeller. 

 

 

http://www.recreationalflying.com/tutorials/groundschool/propeller.html#windmilling

Mathematically, the effect is given a good approximation by treating a windmilling propeller as a solid disc of the same diameter.

That answer your question, Dietrich? 

Make more sense, now?

[taildraggernut]

Yep...even in a dive.  Again, if you fly a constant speed propeller aircraft, the windmilling propeller is one of the properties that gives you such excellent speed control on descent (final approach).

 

End of Story. 

 

You don't seem to be able to stay on topic, talk about rabbit holes.

 

You are flying along in the early Spit in level flight and decide to push the nose down (nothing more than a push on the spade grip), the first thing that happens is the aircraft will speed up due to reducing drag and a little help from gravity, you manage reach a point where enough negative g is reached and the engine 'coughs' (half a second or maybe a second) and you stabilise the aircraft in the dive and the engine recovers, half to a full second of engine  'cough' is not going to have a brick wall effect you seem to be portraying, you only have to try this in a real CS prop equipped aircraft and see for yourself, simulate a 1 second cough by closing the throttle as you do the push, the aircraft will not slow down, it just won't accelerate as quickly as a constantly running engine.

 

End of story, close the text books and go out and see how the real world works.

[ACG_Invictus]

That is hilarious.

It was at that!

[Crump]

You don't seem to be able to stay on topic, talk about rabbit holes.

 

You are flying along in the early Spit in level flight and decide to push the nose down (nothing more than a push on the spade grip), the first thing that happens is the aircraft will speed up due to reducing drag and a little help from gravity, you manage reach a point where enough negative g is reached and the engine 'coughs' (half a second or maybe a second) and you stabilise the aircraft in the dive and the engine recovers, half to a full second of engine  'cough' is not going to have a brick wall effect you seem to be portraying, you only have to try this in a real CS prop equipped aircraft and see for yourself, simulate a 1 second cough by closing the throttle as you do the push, the aircraft will not slow down, it just won't accelerate as quickly as a constantly running engine.

 

End of story, close the text books and go out and see how the real world works.

 

 

Why don't we just ballpark it real quick hotrod....

 

10.9 foot diameter propeller windmilling =  Pi * (10.9)^2 = 373 ft^2 + 242ft^2 wing area = 615ft^2 reference area

 

150 knots level speed 

 

CD at 150 KEAS for a Spitfire Mk 1 = .028

 

Dynamic Pressure = 76.27psf

 

Total Drag produced = CDqS = .028*76.27psf*615Ft^2 = 1313lbs drag force in pounds (or negative thrust because we are not producing any thrust with a windmilling propeller) + 522lbs of drag produced in order to fly at that speed = 1835lbs of drag

 

We are not producing thrust  and are decelerating at a rate of:

 

6050lbs/32.2ft/s^2 = 187.8 Slugs

 

1835lbs / 187.8 Slugs = 9.77ft.

 

Vf = Vi +a*t

 

Vf-Vi = a*t

 

(Vf-Vi)/a = t

 

Vf-Vi = 20 mph or 29fps

 

29fps/9.77ft/s^2 = 2.9 seconds

 

In 2.9 seconds I will lose 20 mph airspeed....

 

Notice in the film my level airspeed never changes once the negative G cut out occurs..

 

so we have to dive in order to speed up...

 

In the film I posted of CloD, I put the nose down about 25 degrees.

 

6050lbs of airplane at a 25 degree dive angle produces 6050lbs * sin25 = 2556lbs of thrust.

 

2556lbs - 1835lbs = 721lbs of thrust

 

721lbs / 187.8 slugs = 3.8 ft/s^2

 

29fps/3.8ft/s^2 = 5.2 seconds of a constant 25 degree angle required to gain 20 mph airspeed.

 

But I do not hold a constant 25 degree angle....so lets ballpark the effects of the angle change.

 

Average angle between 25 degrees and zero is 12.5 degrees

 

6050lbs * Sin 12.5 = 1309lbs of thrust

 

1309lbs - 1835lbs = 526lbs of drag or negative thrust

 

526lbs/187.8 slugs = 2.8 ft/s^2 deceleration

 

The net effect of dipping the nose down to 25 degrees dive angle and coming back up to level flight is equal to decelerating the airplane at 2.8ft/s^2 from its speed the propeller began to windmill in level flight.  In other words, in the 5 seconds the nose was below the horizon, the airplane should have lost about 14 fps or 10 mph from the airspeed I entered.

 

I should NOT have gained 20mph.......

 

That is how the aircraft performance math works and it describes very well the real world results.

 

It is also very easy to see why a Constant Speed Propeller equipped aircraft is very easy to control the airspeed on final approach when you fine pitch the propeller and reduce the manifold pressure....the airplane slows down quite nicely.

[taildraggernut]

Why don't we just ballpark it real quick hotrod....

 

Hotrod?

 

10.9 foot diameter propeller windmilling = Pi * (10.9)^2 = 373 ft^2 + 242ft^2 wing area = 615ft^2 reference area

 

A = Pi * r ^2  so Pi * 5.45 ^2 = 93.31sqft for the prop, how on earth someone can think the frontal flat plate area of an 11ft  diameter prop is bigger than the planform wing area is frankly comedic,  how does the plan form wing area have any relevance? the drag will be in profile or frontal area form only, the Spitfire does not have 242 sq ft of frontal wing area, you clearly don't know how to handle this science on evidence of this first line alone.

 

https://www.google.co.uk/?gws_rd=ssl#q=circle+area+calculator   dont forget r in this case is 5.45ft if the prop is 10.9ft

 

​https://www.grc.nasa.gov/www/k-12/airplane/dragco.html

 

https://www.grc.nasa.gov/www/k-12/airplane/sized.html

 

 

 

Notice in the film my level airspeed never changes once the negative G cut out occurs..

 

how do you get negative g cut in level flight? why is your film set to private? why do you bother with any of this?

your airspeed of course should increase due to reducing induced drag prior to getting a negative g cut, so if an error lies anywhere it is in this particular portion when a speed increase 'should' be registered.

 

 

 

so we have to dive in order to speed up...

 

Yeah, doesn't matter if you have a VP, CS, fixed pitch or no prop at all, entering a dive speeds the aircraft up.

so you are saying you get a negative g cut before pushing the elevator? aren't you just getting an engine failure? 

 

 

 

In the film I posted of CloD, I put the nose down about 25 degrees.

 

 

the film that is private? it seems everything you come out with has a very limited shelf live before it becomes worthless.

 

 

 

I should NOT have gained 20mph.......

 

at best this is still just an oppinion as clearly you know nothing about maths or it seems basic aerodynamic priciples. 

 

 

 

It is also very easy to see why a Constant Speed Propeller equipped aircraft is very easy to control the airspeed on final approach when you fine pitch the propeller and reduce the manifold pressure....the airplane slows down quite nicely.

 

 

Again this shows how little you know of the mechanics of this, you have clearly heard some 'bar' talk between pilots extolling the virtues of setting the prop levers to fine pitch (high RPM) during the descent and approach phase which is a typical and deliberate action that bears no relevance to momentary engine cuts, it shows clearly how you simply do not understand that the blade angle will not suddenly hit fine pitch with an engine cough as the prop govenor will be trying to maintain a constant speed of prop rotation (you know, that's where the constant speed name comes from), the slowing of the prop is a gradual process, that is why pilots will push the prop levers forward deliberately for the descent phase, because leaving them in the cruise RPM position does not produce the desired instant drag inducing effect.

[Crump]

 

 

Yeah, doesn't matter if you have a VP, CS, fixed pitch or no prop at all, entering a dive speeds the aircraft up.

 

 

You have many things confused!!

 

None of the propellers are windmilling.  If they are windmilling then they create lots of drag...so much it can be called "negative thrust".

 

 

 

you simply do not understand that the blade angle will not suddenly hit fine pitch

 

The instant power is removed...the propeller is windmilling.   Is just isn't noteworthy accounting for the the effect of blades moving to fine pitch.  It is simply minor.

 

 

 

at best this is still just an oppinion

 

No, Its is actual aircraft performance math based on Newtonian physics.  

 

 

 

6050lbs * Sin 12.5 = 1309lbs of thrust   1309lbs - 1835lbs = 526lbs of drag or negative thrust   526lbs/187.8 slugs = 2.8 ft/s^2 deceleration   The net effect of dipping the nose down to 25 degrees dive angle and coming back up to level flight is equal to decelerating the airplane at 2.8ft/s^2 from its speed the propeller began to windmill in level flight.  In other words, in the 5 seconds the nose was below the horizon, the airplane should have lost about 14 fps or 10 mph from the airspeed I entered.   I should NOT have gained 20mph.......

 

 

 

 

 

The net effect of dipping the nose down to 25 degrees dive angle and coming back up to level flight is equal to decelerating the airplane at 2.8ft/s^2 from its speed the propeller began to windmill in level flight.  In other words, in the 5 seconds the nose was below the horizon, the airplane should have lost about 14 fps or 10 mph from the airspeed I entered.

 

Not much else needs to be said.

[taildraggernut]

 

 

You have many things confused!!   None of the propellers are windmilling.  If they are windmilling then they create lots of drag...so much it can be called "negative thrust".

 

 

I have not confused anything.

 

 

 

The instant power is removed...the propeller is windmilling.   Is just isn't noteworthy accounting for the the effect of blades moving to fine pitch.  It is simply minor.

 

in the case of a pushover the power will not be removed until negative g is reached, and again for what? the fith? sixth time explaining this? there is a reduction in induced drag before the engine cut happens, the aircraft 'will' accelerate before any of the effects of windmilling even begin to take effect.

 

the blade angle is a very significant factor in windmilling drag, it is after all what feathering a dead engine is all about.

 

http://naca.central.cranfield.ac.uk/reports/1934/naca-report-464.pdf

 

 

 

No, Its is actual aircraft performance math based on Newtonian physics.

 

Well I have seen your handling of basic maths in the first line of your previous post so I stand by my point.

 

 

 

Not much else needs to be said.

 

I agree, you really need to step away, this must be embarrassing for you. 

[Crump]

 

 

agree, you really need to step away, this must be embarrassing for you. 

 

Not really nor am I surprised from dealing with you in the past at your behavior.

 

Not exactly sure what the point of your mindlessly posting a report that says everything I have already told you.  Probably should read the things guy.  

 

Not only does it discuss the NEGATIVE THRUST produced, it is an early report that discusses possible uses such as controlling the airspeed in a dive and reducing landing distance!

 

 

http://naca.central.cranfield.ac.uk/reports/1934/naca-report-464.pdf

 

It even talks about why you add the disc area to the 1G level reference area.....

 

hint...that accounts for the shape of the body behind the propeller.

10.9 foot diameter propeller windmilling =  Pi * (10.9)^2 = 373 ft^2 + 242ft^2 wing area = 615ft^2 reference area

 

150 knots level speed 

 

CD at 150 KEAS for a Spitfire Mk 1 = .028

 

Dynamic Pressure = 76.27psf

 

Total Drag produced = CDqS = .028*76.27psf*615Ft^2 = 1313lbs drag force in pounds (or negative thrust because we are not producing any thrust with a windmilling propeller) + 522lbs of drag produced in order to fly at that speed = 1835lbs of drag

 

We are not producing thrust  and are decelerating at a rate of:

 

6050lbs/32.2ft/s^2 = 187.8 Slugs

 

1835lbs / 187.8 Slugs = 9.77ft.

 

Vf = Vi +a*t

 

Vf-Vi = a*t

 

(Vf-Vi)/a = t

 

Vf-Vi = 20 mph or 29fps

 

29fps/9.77ft/s^2 = 2.9 seconds

 

In 2.9 seconds I will lose 20 mph airspeed....

 

Notice in the film my level airspeed never changes once the negative G cut out occurs..

 

so we have to dive in order to speed up...

 

In the film I posted of CloD, I put the nose down about 25 degrees.

 

6050lbs of airplane at a 25 degree dive angle produces 6050lbs * sin25 = 2556lbs of thrust.

 

2556lbs - 1835lbs = 721lbs of thrust

 

721lbs / 187.8 slugs = 3.8 ft/s^2

 

29fps/3.8ft/s^2 = 5.2 seconds of a constant 25 degree angle required to gain 20 mph airspeed.

 

But I do not hold a constant 25 degree angle....so lets ballpark the effects of the angle change.

 

Average angle between 25 degrees and zero is 12.5 degrees

 

6050lbs * Sin 12.5 = 1309lbs of thrust

 

1309lbs - 1835lbs = 526lbs of drag or negative thrust

 

526lbs/187.8 slugs = 2.8 ft/s^2 deceleration

 

The net effect of dipping the nose down to 25 degrees dive angle and coming back up to level flight is equal to decelerating the airplane at 2.8ft/s^2 from its speed the propeller began to windmill in level flight.  In other words, in the 5 seconds the nose was below the horizon, the airplane should have lost about 14 fps or 10 mph from the airspeed I entered.

 

I should NOT have gained 20mph.......

 

That is how the aircraft performance math works and it describes very well the real world results.

 

It is also very easy to see why a Constant Speed Propeller equipped aircraft is very easy to control the airspeed on final approach when you fine pitch the propeller and reduce the manifold pressure....the airplane slows down quite nicely.