CWHS

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原帖由 jackieyue 於 25-7-2010 02:22 發表
CWHS 師兄可唔可以解釋o下發生咩事?

小弟唔識野...好似見到佢有d失速...

CF-18係到做緊個High AOA既 Fly By比觀眾睇, 係下面片中睇到crash前聽到Engine "Pop Pop Pop", 咁有可能遇到FOD或bird strikes, 因為飛緊45度AOA時, 已經接緊失速狀態, 如果引擎出現問題, 而且無足夠高度救機, Pilot只好Eject.

http://www.youtube.com/watch?v=AfiCyVKnSSw

CWHS

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原帖由 odyssey2007 於 25-7-2010 11:47 發表


未必係fod, 呢o的咁既aoa 同速度有可能係engine surge/stall
o的咁既高度+ 速度+ aoa 出o的咁既事f 22 都冇得救

Ai丫Ai竟然唔記得呢個可能
片中22-26秒係可救機時間26秒之後就byebye lor
而F-22唔好唔記得有Thrust vectoring, 如果只係一邊ENG有事的, Apply Full Thrust加bank番去左邊, Thrust Vectoring + 4秒反應時間未必死硬

CWHS

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原帖由 odyssey2007 於 25-7-2010 12:49 發表

問題係你O係O的咁既AOA 同速度推唔推到full thrust
gas turbine engine 係靠turbine 黎帶compressor 轉, compressor surge/stall 左你combustion camber 都俾唔到咁多output 俾turbine, turbine 唔夠output compr ...

Remark my post "如果只係一邊ENG有事的", FADEC Mil同Civ唔同Law, 而F-22的F119-PW-100的反應時間要多小, 我看大家去youtube睇片好過睇數據
而我提出F-22上Thrust Vectoring只係救機的一大幫助

CWHS

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原帖由 odyssey2007 於 25-7-2010 14:17 發表
得番一邊engine 你個thrust to weight ratio 就算係f22 都一定細到...咁既ratio 個envelope 會細左好多

平飛入氣順實快, e 家o的777 ar 330 ar 都好快ga (親身體驗過, 靈敏到呢=.="
咁既aoa 同速度入氣冇平飛o ...

比你講埋氣動特性, 以F-22, 咁唔洗講答案啦
addional F-22 的Thrust Vectoring 係做Pitch, Roll, 只係做唔到Yaw (F-35的F-135/6做埋Yaw)

[ 本帖最後由 CWHS 於 25-7-2010 14:44 編輯 ]

CWHS

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原帖由 odyssey2007 於 25-7-2010 15:07 發表


我唔係話f22 氣動唔得, 咁既aoa 同速度, 除非你o個架係雪風, 唔係你覺得咁短時間, 救到機嗎? 睇番f22 o的demo o係o的咁既飛行條件2 個engine w/afterburner 反應力都比唔上正常狀態, 更何況e 家講緊1 engine out ...

問題一: Aileron壞左一邊, 得番一邊function, 那Aileron是否不能使A/C Roll?

additional 我又頭到尾都只係話Thrust Vectoring係幫手, 無話連control surface都壞埋wor

[ 本帖最後由 CWHS 於 25-7-2010 15:41 編輯 ]

CWHS

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原帖由 odyssey2007 於 25-7-2010 15:55 發表


講緊thrust vectoring 又講aileron??
你知唔知f22 點樣唔郁control surfaces 單靠thrust vectoring 黎roll 先? 一邊engine out 單靠thrust vectoring 你點roll???
又講下aileron, 主翼面瀕臨stall 既情況突然一 ...

只係用aileron做例子, 一邊INOP, 另一面function到就Roll唔到嗎?
我相信你明白好多戰機即使到Stall Speed甚至Negative Speed Control Surface依然能夠控制A/C吧
而F-22當年贏YF-23的原因?

此example 以F-22解決方法, Roll Left and sightly pitch down + Apply Full Thrust + Apply Left Rudder -> Control Surface + Thrust Vectoring help Roll Left + rudder compensate -> Recovery.

CF-18見到的是Tailspin stall, 係F-18上係有Spin Recovery System, 會指示recovery, pilot亦要maintain指定AOA.

additional 只要maintain個yaw, 就算both eng flameout, 都唔止得個4秒Lift

[ 本帖最後由 CWHS 於 25-7-2010 16:24 編輯 ]

CWHS

Double post Del....

[ 本帖最後由 CWHS 於 25-7-2010 17:02 編輯 ]

CWHS

Triple Post del..

[ 本帖最後由 CWHS 於 25-7-2010 17:02 編輯 ]

CWHS

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原帖由 odyssey2007 於 25-7-2010 16:36 發表
睇黎你真係唔知f22 點樣唔郁control surfaces, 單靠thrusting 黎roll 呢...

yup, with both engine running+ thrust vectoring+ 自身某o的氣動特性, then? apply 落今次既situation, 有幫助?
我一直都講緊係唔夠 ...

師兄, 你會唔會又頭到尾都係到誤解我, 我無話F-22的Roll是靠Thrust Vectoring Thrust Vectoring只是 Assistance.
CF-18的情況是4秒後Tailspin, If maintain Yaw, A/C Lift會唔止4秒(Perhaps +2~+4), 而Jet ENG Respond要唔要6~8秒?
計算AOA+Low Speed帶多的penalties落埋去, 小弟目視估計當時at least 500ft+, 而認為係呢個envelope下, 對F119有幾大的影響?
要做的只要係失去Lift前令A/C增加Lift就可以Recovery, Civ Twin ENG Jet有好多單都係single Eng flamout + High AOA at final approach, 但又救得番, 反而Mil Jet就唔得?

btw 個Fly by要飛行條件話觀眾安全姐, 但做咩要理Airspace class

CWHS

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原帖由 odyssey2007 於 25-7-2010 16:36 發表
睇黎你真係唔知f22 點樣唔郁control surfaces, 單靠thrusting 黎roll 呢...

yup, with both engine running+ thrust vectoring+ 自身某o的氣動特性, then? apply 落今次既situation, 有幫助?
我一直都講緊係唔夠 ...

btw師兄, pm個MSN黎啦 同你傾空有排傾

CWHS

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原帖由 odyssey2007 於 25-7-2010 17:36 發表
都話睇番個situation, 得番單邊engine 既話以f22 既thrust vectoring 頂多做到少少pitching, 有咩用?
engine 就算o係咁既環境o係4 秒裡面俾到respon 你, 唔好唔記得你只係得一個engine, 仲要唔知上唔上得切high pow ...

師兄呀師兄
MFD+HUD(If function select)+VOICE會出
"bleed air right" + "engine right", "Caution" + "Warning" button + Alarm.
讀個Civ PPL都會教你點做, 一個熟練的Pilot理應了解自己部機的Aerodynamic同flight control, 唔會做出Over Limitation 既事, 由求會致命, 可述係一個Combat Aviator, 唔會你Left Eng INOP敵人就唔打你架ma
而500ft係唔多, 但做到既野唔可以話小, 由求對一部aerodynamic instability咁好既機, 一日你部A/C有Airflow都仲可以郁.
小弟對師兄提出4-8秒內, Engine唔能夠時間respon好有疑問, 除非部機係Full Loading Weapon & Fuel, 否則反應唔會話stall左都未有thrust. 作為一部5th Gen Fighter, 唔會以係4-8秒內respon thrust, 同唔可以achive幾Kts?
經十幾分鐘search完又search, 得知F-15c任可情況下可以4秒內由idle到Full Thrust. 仲搵到句咁既樣, 但師兄應該又會話一邊INOP, 但好像我一直都提及INOP, 亦沒有忘記帶來的pepenalties...(F-22試過4500ft做yoyo maneuver落番唔低過2000ft, 當然both eng ok)
"The two-dimensional nozzle vectors thrust 20 degrees up and down for improved aircraft agility. This vectoring increases the roll rate of the aircraft by 50 percent and has features that contribute to the aircraft stealth requirements."

And 師兄我提出的Civ案例是指 Exceed而唔係Standard Operation AOA, 而唔係話佢地AOA大, 講AOA大, Military Cargo可以仲大. 竟然談到slotted flap呀
事發中CF-18又無事->Tailspin目視估計只係drop左no more than 100ft.
"In aerodynamics, the flight envelope or performance envelope of an aircraft refers to the capabilities of a design in terms of airspeed and load factor or altitude."
"計算AOA+Low Speed帶多的penalties落埋去, 小弟目視估計當時at least 500ft+"我句野又有事? ,講緊AOA + Low Speed Performance limitation.
車同飛機都有樣叫minimum turning radius既東西, 做特技時都excced左呢個limit, 造成好多的能量流失.........但...與直線Flyby無關係哦...

btw師兄有無學過stall/tailspin recovery呢...

CWHS

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原帖由 odyssey2007 於 25-7-2010 20:32 發表
同埋請記得就算4 秒俾你一個ENGINE 上到full thrust, 唔代表你一有thrust 就即刻可以restore from stall

小弟...無氣那... 由頭到尾我都係講有chance
小弟前面講左, CF-18是Tailspin致插水, 如maintain yaw, even both eng inop, A/C Perhaps still have 3 Seconds+ Lift to stay in the air.
即Maintain Yaw, 3.X Second Thrust respond to full wet thrust, if更加係tail spin之前能maintain yaw, 之後還有3 Seconds Lift until stall, 就係呢個時間係loss all lift, stall前lift提升 -> A/C Recovery...

小弟唔多講那, 師兄請...