## Search found 33 matches

Thu Jun 06, 2019 10:34 pm
Forum: Technical/Operations
Topic: Wind tunnel drag test
Replies: 16
Views: 2276

### Re: Wind tunnel drag test

Because of induced drag. Are the aerofoils identical in profile and area? Are the measurements you have shown raw data ( they don’t look non dimensionalised). Fred Sent from my iPhone using Tapatalk I use one same airfoil for both test..Numbers are in grams.. But you must know that this situation i...

Thu Jun 06, 2019 10:15 pm
Forum: Technical/Operations
Topic: Wind tunnel drag test
Replies: 16
Views: 2276

### Re: Wind tunnel drag test

do you have data for 0 degrees? Fred Sent from my iPhone using Tapatalk I didnt meassure zero AoA,but I can do it..Why do you ask? Can you explain why you think that 3D test must have greater drag ,what will increase drag if I didnt increase AoA on 3D airfoil? Because of induced drag. Are the aerof...

Thu Jun 06, 2019 9:47 pm
Forum: Technical/Operations
Topic: Wind tunnel drag test
Replies: 16
Views: 2276

### Re: Wind tunnel drag test

Hang on... induced drag would exist in the 3D case as a function of lift coefficient ^2 however the lift coefficient would not increase at the same rate as the 2 d example due to edge effects. I.e. the lift-curve slope would be less than the 2d case at 2pi/rad. The 2d case has no lift induced drag....

Thu Jun 06, 2019 9:32 pm
Forum: Technical/Operations
Topic: Wind tunnel drag test
Replies: 16
Views: 2276

### Re: Wind tunnel drag test

Lol! Yes. Too much wine! Sent from my iPhone using Tapatalk 3D test will show lower drag. Airfoil tips in 3D test are open end,so there is pressure loss on this region,there is no wall(end plate) which will stop this pressure to "escape",so drag and lift are reduced. (If we want have same...

Thu Jun 06, 2019 9:31 pm
Forum: Technical/Operations
Topic: Wind tunnel drag test
Replies: 16
Views: 2276

### Re: Wind tunnel drag test

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Thu Jun 06, 2019 9:02 pm
Forum: Technical/Operations
Topic: Wind tunnel drag test
Replies: 16
Views: 2276

### Re: Wind tunnel drag test

3D year will produce lower drag. The fact that that both edges of the aero foil are touching the wall make it more approximate to a wing of infinite span which assuming incompressible low speed flow means no lift induced drag. Don't you mean 2D will produce lower drag? I'd agree with that. Lol! Yes...

Thu Jun 06, 2019 5:44 pm
Forum: Technical/Operations
Topic: Wind tunnel drag test
Replies: 16
Views: 2276

### Wind tunnel drag test

-we use same airfoil and same AoA and airflow speed in both tests -wind tunnel have adjustible walls so we can use it as 2d or 3d test,also meassure lift and drag... Test "2D" -AoA 15 degrees -airfoil tips are "connect" with wind tunel walls,so there is no gap between tips and wa...

Sun May 05, 2019 1:23 pm
Forum: Technical/Operations
Topic: How reduced AoA increase drag?
Replies: 8
Views: 1275

### Re: How reduced AoA increase drag?

No I dont think that reduced AoA cause higher drag, I am confused how reduced AoA can increase drag in explanation how wingtip vortices (induced drag topic) change (reduced )relative airflow on wing. qoute from text: " The wing tip vortices produce a swirling flow of air behind the wing which ...

Sun May 05, 2019 9:09 am
Forum: Technical/Operations
Topic: How reduced AoA increase drag?
Replies: 8
Views: 1275

### Re: How reduced AoA increase drag?

" Lets back up. WHY do you think reduced reduced AOA causes a higher drag? And would you be convinced if I showed you a million web pages that says the opposite? No I dont think that reduced AoA cause higher drag, I am confused how reduced AoA can increase drag in explanation how wingtip vorti...

Sat May 04, 2019 1:37 am
Forum: Technical/Operations
Topic: How reduced AoA increase drag?
Replies: 8
Views: 1275

### Re: How reduced AoA increase drag?

"Induced drag has reduced effective AoA" I don't understand these words. But if it helps, reduced AOA in the non-stall condition produces lower drag and lower lift. Look at this picture Angle between chord line and effective airflow is smaller than angle between chrod line and freestream ...

Fri May 03, 2019 9:32 pm
Forum: Technical/Operations
Topic: How reduced AoA increase drag?
Replies: 8
Views: 1275

### How reduced AoA increase drag?

Induced drag has reduced effective AoA,so how lower AoA can increase drag if ussually lower AoA decrease drag? https://upload.wikimedia.org/wikipedia/en/archive/3/39/20120303202742%21Induce_drag_downwash.png drag increase when AoA increase,so if AoA is smaller then drag will also smaller.... https:/...

Mon Apr 29, 2019 4:54 pm
Forum: Technical/Operations
Topic: Vortex drag-induced drag
Replies: 5
Views: 1204

### Re: Vortex drag-induced drag

You can not influence the future from the past,figuratively said.. Yes you can. The flow field behind the wing absolutely influences the flow in front of and around the wing (for a subsonic flow), because pressure waves can travel upstream. So the flow "knows" the wing is coming. (I suppo...

Mon Apr 29, 2019 7:47 am
Forum: Technical/Operations
Topic: Vortex drag-induced drag
Replies: 5
Views: 1204

### Re: Vortex drag-induced drag

Not 100% rigorous, but close enough for A.net purposes -- Think of the wingtip vortex and its effects (downwash) as starting from the leading edge, i.e., from the "present" using your type of description, and extending from there to the trailing edge and beyond (i.e., the past). How do yo...

Sun Apr 28, 2019 10:12 am
Forum: Technical/Operations
Topic: Vortex drag-induced drag
Replies: 5
Views: 1204

### Vortex drag-induced drag

It is write that vortex on wingtip cause downward velocity(downwash) which reduce effective angle of attack to wing(AoA),thus lift vector tilted more backwards which cause induced drag... 1)Downwash is airflow with downwards movement BEHIND wing trailing edge.... How airflow BEHIND wing can change d...

Mon Mar 18, 2019 4:56 pm
Forum: Technical/Operations
Topic: How raked wingtips reduce induce drag?
Replies: 3
Views: 1469

### How raked wingtips reduce induce drag?

Hi all, I understand that both winglets and raked wingtips are for the same function (from what I have read) - to reduced the amount of induced drag. I understand the principles behind winglets, however I am uncertain how raked wingtips actually achieve this? Could anyone please explain the aerodyna...

Thu Feb 07, 2019 8:53 pm
Forum: Technical/Operations
Topic: Altimeter indicated altitude vs aircraft speed,bernoulli
Replies: 27
Views: 2649

### Re: Altimeter indicated altitude vs aircraft speed,bernoulli

I put wrong picture of instrument (testo510 he meassure differential pressure) this is testo511, it has only one port for connection,reference pressure is vacuum bacause he meassure apsolute/barometric pressure.. https://ae01.alicdn.com/kf/HTB15duxIpXXXXcdXFXXq6xXFXXXj/Testo-511-NEW-Absolute-Aire-Pr...

Thu Feb 07, 2019 8:12 pm
Forum: Technical/Operations
Topic: Altimeter indicated altitude vs aircraft speed,bernoulli
Replies: 27
Views: 2649

### Re: Altimeter indicated altitude vs aircraft speed,bernoulli

after video silence like on cemetery You created a separate thread for your video. I posted there yesterday. Check it out. I will answer here becuase this thread is dead. For sure calibration is good to have. I have testo 511 ,this is instrument that meassure apsolute pressure/barometric pressure.I...

Tue Feb 05, 2019 6:54 pm
Forum: Technical/Operations
Topic: Altimeter indicated altitude vs aircraft speed,bernoulli
Replies: 27
Views: 2649

### Re: Altimeter indicated altitude vs aircraft speed,bernoulli

after video silence like on cemetery

Mon Feb 04, 2019 6:18 pm
Forum: Technical/Operations
Topic: Find ideal static port position
Replies: 1
Views: 653

### Find ideal static port position

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Mon Feb 04, 2019 5:26 pm
Forum: Technical/Operations
Topic: Altimeter indicated altitude vs aircraft speed,bernoulli
Replies: 27
Views: 2649

### Re: Altimeter indicated altitude vs aircraft speed,bernoulli

It's clear that you're here to lecture on things you haven't the slightest idea about. You've asked questions, which have been answered, repeatedly. I'm putting you on the ignore list, where you belong. Please,my intent was not to argue with members maybe may english is also problem because it is n...

Mon Feb 04, 2019 9:31 am
Forum: Technical/Operations
Topic: Altimeter indicated altitude vs aircraft speed,bernoulli
Replies: 27
Views: 2649

### Re: Altimeter indicated altitude vs aircraft speed,bernoulli

It seems that everyone knows this but you. Your questions have become circular and it's clear you don't know what you're talking about, between drilling holes in airplanes and hair dryers by static ports. Hopefully you don't work on or around aircraft. As you know there is lots off small plane wich...

Mon Feb 04, 2019 7:04 am
Forum: Technical/Operations
Topic: Altimeter indicated altitude vs aircraft speed,bernoulli
Replies: 27
Views: 2649

### Re: Altimeter indicated altitude vs aircraft speed,bernoulli

It seems that everyone knows this but you. Your questions have become circular and it's clear you don't know what you're talking about, between drilling holes in airplanes and hair dryers by static ports. Hopefully you don't work on or around aircraft. It's unclear if your'e actually asking questio...

Mon Feb 04, 2019 6:50 am
Forum: Technical/Operations
Topic: Altimeter indicated altitude vs aircraft speed,bernoulli
Replies: 27
Views: 2649

### Re: Altimeter indicated altitude vs aircraft speed,bernoulli

The problem is that you are making assumptions that have no basis in the actual science involved. For critical thinking to work, the assumptions made have to have a basis in actual fact, not imagined fact. Start studying here and report back when you actually understand Bernoulli's Ventura principl...

Sun Feb 03, 2019 1:11 pm
Forum: Technical/Operations
Topic: Altimeter indicated altitude vs aircraft speed,bernoulli
Replies: 27
Views: 2649

### Re: Altimeter indicated altitude vs aircraft speed,bernoulli

Airflow may move over a static port, but you need to understand that the rule you're trying to apply here may be the wrong application. Airflow moving fast does not necessarily equate to a pressure drop. It can, but I don't think you understand the principle, let alone the application. S. my theret...

Sun Feb 03, 2019 10:40 am
Forum: Technical/Operations
Topic: Altimeter indicated altitude vs aircraft speed,bernoulli
Replies: 27
Views: 2649

### Re: Altimeter indicated altitude vs aircraft speed,bernoulli

All of that is food for thought, but also mostly irrelevant, because the two answers to your question that really matter are A) the static ports are located on the fuselage in a place where speed and angular changes make little difference and static pressure is nearly always neutral, and B) in high...

Sun Feb 03, 2019 9:54 am
Forum: Technical/Operations
Topic: Air Pressure Adjacent to Fuselage Side and Tail Cone
Replies: 11
Views: 2462

### Re: Air Pressure Adjacent to Fuselage Side and Tail Cone

Areas that you might expect to be high pressure may be quite different than expected. For example, I once had a windshield blow out in a Cessna 421, which is a light twin piston engine airplane. There was virtually no airflow into the cockpit, or cabin, however, and I could put my hand through the ...

Sun Feb 03, 2019 9:10 am
Forum: Technical/Operations
Topic: Altimeter indicated altitude vs aircraft speed,bernoulli
Replies: 27
Views: 2649

### Re: Altimeter indicated altitude vs aircraft speed,bernoulli

The point of a static port is that it is placed in a location of neutral, or static pressure. The static port is located in a place where variations in pressure are minimized, and placed on opposite sides of the aircraft to average the pressure between them. Altimeters and airspeed indications in t...

Sun Feb 03, 2019 7:10 am
Forum: Technical/Operations
Topic: Altimeter indicated altitude vs aircraft speed,bernoulli
Replies: 27
Views: 2649

### Re: Altimeter indicated altitude vs aircraft speed,bernoulli

Angle of attack, sideslip, airspeed, configuration, ground effect, dynamic maneuvers . . . it all screws it up. https://apps.dtic.mil/dtic/tr/fulltext/u2/a280006.pdf (go to page 61) http://www.nasa.gov/centers/dryden/pdf/88377main_H-2044.pdf If those don't help, one of the references at the back wi...

Sat Feb 02, 2019 11:43 pm
Forum: Technical/Operations
Topic: Altimeter indicated altitude vs aircraft speed,bernoulli
Replies: 27
Views: 2649

### Altimeter indicated altitude vs aircraft speed,bernoulli

Altimeter use static port to measure barometric pressure on which plane fly.. Static port is located on fuselage,prependicular to airflow. Faster the plane is flying ,faster the airflow over static port,so from bernoulli , pressure over static port must decrease when plane going faster and faster.. ...

Wed Jan 02, 2019 12:48 pm
Forum: Technical/Operations
Topic: QFE-kollsman window
Replies: 6
Views: 1054

### Re: QFE-kollsman window

I’m not sure of the difference, I’m just aware that old mechanical ones stop at 28” and the glass cockpit ones go down to 16”. Does China really use QFE at the Tibetan airports? GF I dont know ,but they can give you QFE if you ask them.If I want that altimeter indicate height above Tibetan airport ...

Tue Jan 01, 2019 4:22 pm
Forum: Technical/Operations
Topic: QFE-kollsman window
Replies: 6
Views: 1054

### Re: QFE-kollsman window

The modern “glass” cockpit altimeters I’ve seen go down to 16” which is what you’d need to use QFE at 4000m. Now, are they certified that low, I can’t say. Gf Is that mechanical altimeters or electric/electronic alt? I am talking about classic mechanic altimeters,that almost every goes "only&q...

Tue Jan 01, 2019 1:36 pm
Forum: Technical/Operations
Topic: QFE-kollsman window
Replies: 6
Views: 1054

### QFE-kollsman window

If we have aircraft stay on airport at 4000 meters and set pointers to 0 feets,how much hPa will kollsman window show? On 4000m is only approx 600hPa but barometric scale in kollsman window is only 950-1050hPa. Or same question ask on diffrent way,If we fly above this airport(at 4000m) and ask airpo...

Tue Jan 01, 2019 11:24 am
Forum: Technical/Operations
Topic: Knob-pointers-kollsman window, mechnical relation
Replies: 3
Views: 872

### Knob-pointers-kollsman window, mechnical relation

Can someone explain in DETAIL what happends when you rotate knob then pointers and barometric scale is rotate together but when you fly rotate only pointers,what is mechanic behind that? Does when rotate knob cause aneroid wafer to spread out/in or just pointers is moving etc ... https://www.youtube...