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Area-51
Joined: 03 May 2021
Posts: 398
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 Posted: Mon Apr 24, 2023 4:12 pm Post subject: The Obsidian Files - Doorly Departed |
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Have been looking forward to this one...
The outcome was disappointing.. was expecting wind in the cockpit; and thats all that really happened... 🤷🏼♂️
Drag went up 19kg at 100kt for a twin door departation and 8kg for a single door scenario... on both events the wind came into the cockpit!! It swirled around and down into the footwells and rear luggage wells, where it swirled around some more before shooting out straight up at the human head like an upper cut from both front an rear directions on its way to escaping out and over the rear of the door frame... Anything left loose in the cockpit is getting sucked up and is going out an opening after slapping the occupants in the head.. for a dual door situation the swirl remains left and right sided; leaning one's head to the centre and back may find a pool of calmness... A single door situation is more exciting; the swirl comes up to the opening on a diagonal from the opposite side hitting the human closest to the opening in the head from the front and rear on the way out; anything left loose in the luggage well, shelf, footwell is going out the opening after slapping the occupant in the face; the occupant can be human dog or cat... a small dog like chihuahua is probably going out the opening... a loose ipad; out the opening... and that's about it..
The aircraft is flyable without one or both doors but it won't be very pleasant at all with 25-30kt 70db winds swirling around in the cockpit like a tornado....
Area-51 "does not" recommend flying any Europa with doors intentionally removed.
Maybe some deflectors will improve a doorless situation... 🤔
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2016 Time(s) |
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| Squiggly Lines - Single Door |
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| Mostly Windy - Head Level |
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| Wind Direction - Going Rearward |
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| Wind Noise - Moderately Noisy But Not That Loud |
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| Wind - Squiggly Lines Very Loose And Messy... Not Conducive To Enjoyment |
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2016 Time(s) |
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wdaniell.longport(at)gmai
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| Posted: Mon Apr 24, 2023 4:47 pm Post subject: The Obsidian Files - Doorly Departed |
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Interestingly my colombian friend whose door opened in flight reported the very same thing. His pax grabbed and partially closed the door.
He was worried that the cover would exit the door and wrap round the tail...In the attempt to catch the cover his passenger let go of the door handle and away went the door.They did catch the cover tho.
William Daniell
+1 786 878 0246
On Mon, Apr 24, 2023, 20:14 Area-51 <goldsteinindustrial(at)gmail.com (goldsteinindustrial(at)gmail.com)> wrote:
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Area-51
Joined: 03 May 2021
Posts: 398
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| Posted: Mon Apr 24, 2023 7:01 pm Post subject: Re: The Obsidian Files - Doorly Departed |
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Thanks for the input William... Its amazing how the computer can mathematically estimate actuals. Something like a cover could wrap around the head very quickly.
How the door departs once detached is not yet known however on assessment the trailing airflow once departed remains off centerline and skims over the top of the horizontal stab, so at this stage we could assume the cover would of shot past the pax side of the vertical stab and kept going had the pax chosen to focus on the door instead.
I'm not totally finished on this one yet and want to look at how the complete airframe responds in the 3 axis environment when a door departs.
All analysis so far are just preliminary static tests to identify generated sound levels and fluid reaction around the component body.
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Area-51
Joined: 03 May 2021
Posts: 398
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| Posted: Mon Apr 24, 2023 11:47 pm Post subject: Re: The Obsidian Files - Doorly Departed |
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Some further numbers were run this afternoon after William's comment, focusing on trailing wash affecting the horizontal stab and items snagging on a control surface.
Airspeed was increased from 100kt to 150kt with some interesting results... basically, flying faster reduces the turbulence within the cockpit after a door departs.
The other outcome noticed while slicing through the layers of velocity tracing was all the turbulent flow exits the cockpit at the top inner rear corner of each door port; the sides of the fuselage remain fairly unaffected and away from the wash; so it would not be too untrue to assume anything such as cloth or lite items sucked out of the cockpit possess little chance or risk toward hitting or snagging on the horizontal stab.
So the numbers indicate fly faster to be in a windy bus stop, or fly slower and sit in a tornado... personally not excited or outwardly wishing anybody find themselves in the situation to prove the theory correct.
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| Description: |
| Door Departed - Dual - 150kt - H Stab Level |
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56.5 KB |
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1978 Time(s) |
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Area-51
Joined: 03 May 2021
Posts: 398
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| Posted: Tue Apr 25, 2023 12:45 pm Post subject: Re: The Obsidian Files - Doorly Departed |
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More insight was extracted last night from this study... how the air enters the cockpit after the door has departed; at the lower rear frame rail... it then whips around at the centerline toward the front for the uppercut rearward exit; this creates a vortex in the lower luggage well, and another in the front footwell up to head area.
Several deflectors were tested at 100kt.. upper forward rail visor, side forward visor, a lower side rail board, and rear lower rail louvre... all additions performed some affect with the louvre setup providing the best outcome toward reducing cockpit turbulence to a pleasant level while doorless and reducing Drag while increasing Lift. The upper visor provides the least effect, and the side mounted visor an acceptable affect.
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| Velocity - Cabin Ingress - Lower Rail Level |
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55.38 KB |
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Area-51
Joined: 03 May 2021
Posts: 398
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| Posted: Sat May 13, 2023 4:32 am Post subject: Re: The Obsidian Files - Doorly Departed |
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After some further real world feedback on this some more trials were run at 36m/sec (70kt) velocity; simulating loosing a door just after take off... and the simulation matched the real world account of sedate level of turbulence and acoustic noise within the cockpit.
The velocity within the cockpit is only around 5m/sec, and acoustic noise about 60db... the swirl is also very sedate; so no real tendency for maps or the chihuahua to be disturbed at all... so while flying faster improves the flow of air over the fuselage within the simulation, flying slower results in an overall more comfortable experience.
From here we can move forward into Transient Time Based analysis in which the active physical departure of the door is simulated through both time and space to help predict the risk of impact with the rearward section of the airframe.
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1882 Time(s) |
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