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Vibration with Wing Size Altitude Speed and MTOW

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Vibration with Wing Size Altitude Speed and MTOW

Old 16th Sep 2023, 11:34
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Vibration with Wing Size Altitude Speed and MTOW

Experienced Engineers and Pilots

With your experience, how doth vibration relate to wing size (span, depth, thick, m2), speed, altitude (and method flying), and MTOW (that day). (Could say if propellor (and)else jet), and any notes of manouevres.

If a 14m wingspan single fuselage airplane flying at different altitudes (Sea Level, 1000ft, 2000ft, 3000ft, E.T. CetERa), from nr stall to 100kts, 200kts, 300kts, 400kts, 500kts, 600kts, 700kts, 800kts, 900kts, what the experience of the pilot, what the experience of the airplane.

If a 14m wingspan wing, 5m chord at wingtip, though 11-12m chord at root, solid wing say 0.3metre thick and say 90-130m2, say 6g (could be 9g) low level, what the experience (stall to 1000kts). Tolerable. Horrid. Beautiful. (K)New Set Teeth. Wish use ffffaacccciiiilLITeaseee. Calvin (and Hobbes) sight on too much caffeine.

We each know the long thin wing for low level flying hence less vibration since less chord (though weight of centre fuselage and wing fuel/engines affecting oscillation), though what the experience of pilots with different wings (and if jet, if propeller (on wing, on nose)).

What the experience of Tornado and F14 low level with spread wings (and what rough max speed)

What the experience of Tornado and F14 low level with swept wings (and what rough max speed)

What Vibration spectra and tolerance

If cruise
(If 14m span, 90-130m2, 5m tip, 11-12m root, say 0.3m thick, 50kts 100kts 200kts 300kts 400kts 500kts 600kts 700kts 800kts 900kts 1000kts
500ft 1000ft 2000ft 3000ft......42,000ft.)

If shortterm manoeuvre (and what stress calc for such wing if +6g (could be 9g)(and -2-6g) if structure wood, else composite, else metal, (think low level military flying and acrobat).

MTOW 10,000kg, 15,000kg, 20,000kg, 25,000kg, 30,000kg, single fuselage (though shall have weight store outboard each wingtip)

Some say the Blackburn Buccaneer relatively smooth low-level flight though say Panavia Tornado relatively rough
Some say the DeHavilland Vampire very smooth and long glide

What tolerable airplane

and what airplane of vibration a problem for the pilot
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Old 18th Sep 2023, 15:13
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Very difficult to read post as you are throwing so many variables and confusing (incorrect) terms together. I'm thinking you're talking about gust (turbulence) response. Vibration is something else. Start reading up on wing loading here: https://en.wikipedia.org/wiki/Wing_loading and don't forget to look at some of the references (books, online documents and articles) listed there.
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Old 19th Sep 2023, 16:07
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Vibration due to Wing Choice

They say that vibration with low-level flying is significant (and consider air turbulence/movement normal to the trajectory of the airframe)

They say that a narrow (short chord) thin (high aspect ratio) wing is the choice when low-level flying since that reduces vibration experienced by the pilot and airframe (less wing for the (vector normal relative to trajectory of the airframe) air to grab), though the centre fuselage oscillates with the length of those (aspect ratio) long narrow (short chord) wings (with without damping and vibration with engines, fuel), and ALLEGED less skin friction with short chord (though longer span).

The Panavia Tornado shifts from low aspect ratio wing swept (say around 8.5m span) to relatively high aspect ratio narrow-chord wing spread (say around 14m span) when low-level flying at relevant speeds, and one of the reasons is reducing vibration experienced by the pilots and(ing) the airframe and loads (catch less air to buffet wing thence transmit less vibration, and vibration filter-amplifier). And the weight of the centre fuselage then oscillates relative to the wingtips, from hugging low aspect ratio wings, to wings spread wide, different vibration amplitude and phase and frequency spectra of centre load relative to different spans (and structures), and with without wing fuel engines loads.

If a design doesnt want to use a long narrow (short chord) wing and instead wants to use a short (say 14m wingspan) solid (could be louvre) wing that gets 90-120m2, those designing want consider whether the vibration significant, without having that wing available to test thus-far.

If, say, flying that at 300kts low level acceptable, though 500kts low level teeth digestive system jarring, and the transition from 378-423kts hence saying what that wing choice thence what flying (lack of)qualities, who can say, from experience.

Hence, say, if a 14m wingspan 0.3m thick solid wing of 90-120m2, say 1 ton load each wing tip, 5m tip chord, say around 11-12m root chord, flying low-level, centre fuselage jet/rocket propulsion, stall-->1200kts low level, what the vibration experienced by the pilot, crew, those in the airplane, and the airframe, and hence what that wing arrangement (lack of) flying qualities hence choice.
Is Calvin & Hobbes Calvin on loads of Cereal Sugar Caffeine trying to read instruments else calm (though Airframe on Caffeine too much Sugar) else... all smooth at 400kts 30ft altitude 500kts 600kts 700kts 800kts 900kts 1000kts 1100kts 1200kts

How does Aspect Ratio, wing shape and span and m2 (ft2), and thickness, relate to acceptable and non-acceptable, comforting and noncomforting, tolerable and non-tolerable, smooth, terrible, vibration (Amplitude and Spectra), at relevant altitudes and speeds, hence those that design (nonstandard) airplane get a feel of that at the start.

What are pilot and TP and FTE experiences with each airplane, and preferences of airplane (and airfoil). What are aero eng and structural calc design experiences methods.
They say (wood and metal) DeHavilland Vampire smooth and long glide though semi low aspect ratio at 300-450kts low level.
They say Blackburn Buccaneer preferable to Panavia Tornado if low level flying.

What was asked was, say
MTOW 10,000kg 15,000kg 20,000kg 25,000kg 30,000kg 35,000kg
Wing fixed 14m span (and consider fixed16m span and fixed 18m span max) and thick 0.3m and need 90-120m2 if effective enough with lift and tight turns/moshing-flight
Relatively low Aspect Ratio (14m span), 5m tip chord (can consider 4m tip chord), say around 11-12m root chord (and those that want say, which has more drag, equivalent 90-120m2 long high-aspect-ratio narrow short-chord wing or 14m relatively low-aspect-ratio wing of 11-12m root chord)

Velocities from stall to 1200kts (100kt increments) at all altitudes (0-42,000ft (from 500ft in 1000ft increments))

Say +/- 6g and fully aerobatic (and could consider the +9g -2g norm)

Altitudes (each choice of kts from stall to 1200kts at each altitude) from 500ft to 42,000ft in 1,000ft increments

Structural and Exterior Material Wood (natural wood, plywood, Duramold), else Carbon Fibre Composite, else Metal

Wing Tip with fixed (here on Pprune website unspecified) load (say each wingtip 1 ton)

Centre fuselage jet/rocket engine(s) though consider any relevant propulsion method,

Consider centre fuselage propulsion, and pilot TP FTE and aero experience of airplane with wing-mount engines and fuselage-mount engines, and preferences, feelings, of airfoil, wing shape, (with MTOW and speed and altitude), and which pleasure to fly and which teeetttthhhhdddiiigggeesssttttiivvveeessyyysstteemmmjjjjjaaa rrrrinnng

Haven't any money for responses hence consider

Did work at Boscombe Down some while ago, so could use flim flam lingo if obliged (12,375 rounds report signing before ESSENTIAL released), though colloquial here
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