wh
发帖数: 141625 | 1 应友之托，瞎翻了一首19世纪英国诗人Gerard Manley Hopkins的诗《Ode to Purcell
》——Purcell是17世纪的英国巴洛克风格作曲家。19世纪的诗其实还不算太现代，大
致意思还明白：高声赞美Purcell的厉害。但逐字翻译很吃力，第一句就不明白意思，
后面很多字句、意象也不明所以。我不会写诗，只按字面瞎猜乱翻……不怕笑话地贴出
来，一是想问几个不明白的地方，二是有些喜欢的词句和大家分享。
HAVE, fair fallen, O fair, fair have fallen, so dear
To me, so arch-especial a spirit as heaves in Henry Purcell,
An age is now since passed, since parted; with the reversal
Of the outward sentence low lays him, listed to a heresy, here.
美妙降临了，噢，美妙已降临，如此宝贵
对我，亨利·普赛尔高举起一个如此特殊的心灵，
那个时代已逝去... 阅读全帖 |
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c***d
发帖数: 996 | 2 ☆─────────────────────────────────────☆
thrust (Thrust Jaeina) 于 (Thu Jul 12 18:59:00 2007) 提到:
A a=x;
和
A a(x)
毕竟还是有区别的
前一个是直接找从x到A的(implicit)转换,这中间只许一次user-defined conversion
后一个是列出A的constructors,再找从x到constructor参数的转换.这样实际上可以有
两次user-defined conversion.
☆─────────────────────────────────────☆
thrust (Thrust Jaeina) 于 (Thu Jul 12 18:59:58 2007) 提到:
听上去很象回字的4种写法...不过class一多,里面的conversion function设计还是很
麻烦的.
☆─────────────────────────────────────☆
hypo (三十未满) 于 (Thu Jul 12 19:28:16 |
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c**i
发帖数: 6973 | 3 Andrew E Kramer, Aloft, a Russian Image Problem. New York Times, Aug 30,
2011.
http://www.nytimes.com/2011/08/30/business/global
/russia-hits-headwinds-in-selling-airliners-to-the-west.html?_r=1&scp=1&sq=
superjet&st=cse
Note:
(a) Aeroflot
http://en.wikipedia.org/wiki/Aeroflot
(Aeroflot, English translation: "air fleet"; the flag carrier and largest
airline of the Russian Federation; Founded 1923; Headquarters Moscow; The
airline is owned (as of March 2007) by the Russian Government)
(b) The a... 阅读全帖 |
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b********n
发帖数: 38600 | 5 Pentagon’s big budget F-35 fighter ‘can’t turn, can’t climb, can’t run’
http://blogs.reuters.com/great-debate/2014/07/14/pentagons-big-
The U.S. military has grounded all its new F-35 Joint Strike Fighters
following an incident on June 23, when one of the high-tech warplanes caught
fire on the runway of a Florida air base. The no-fly order — which affects
at least 50 F-35s at training and test bases in Florida, Arizona,
California and Maryland — began on the evening of July 3 and continued
throu... 阅读全帖 |
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a***k
发帖数: 1038 | 6 【 以下文字转载自 paladin 讨论区 】
发信人: atack (小军号), 信区: paladin
标 题: 红死病 by 杰克.伦敦
发信站: BBS 未名空间站 (Sat Oct 11 07:40:15 2014, 美东)
I
The way led along upon what had once been the embankment of a railroad. But
no train had run upon it for many years. The forest on either side swelled
up the slopes of the embankment and crested across it in a green wave of
trees and bushes. The trail was as narrow as a man's body, and was no more
than a wild-animal runway.
Occasionally, a piece of rusty iron, showing through ... 阅读全帖 |
|
m**c
发帖数: 7349 | 7 He took her in his arms again and drew her to him, and suddenly she became
small in his arms, small and nestling. It was gone, the resistance was gone,
and she began to melt in a marvellous peace. And as she melted small and
wonderful in his arms, she became infinitely desirable to him, all his blood
-vessels seemed to scald with intense yet tender desire, for her, for her
softness, for the penetrating beauty of her in his arms, passing into his
blood
. And softly, with that marvellous swoon-lik... 阅读全帖 |
|
j****3
发帖数: 2836 | 8 http://www.chinadefenseobservation.com/?p=4243
China claims to have a working version of NASA’s impossible engine orbiting
the Earth
Scientists in China claim they’ve created a working prototype of the ‘
impossible’ reactionless engine – and they say they’re already testing it
in orbit aboard the Tiangong-2 space laboratory. And will use it in
satellites ‘imminently’.
The radical, fuel-free EmDrive recently stirred up controversy after a paper
published by a team of NASA researchers appeared to ... 阅读全帖 |
|
f****t
发帖数: 15913 | 9 F16低空最大速度是1。2马赫，和歼十一样，楼主是真SB
*********************************
Specifications (F-16C Block 50)[edit]
GENERAL DYNAMICS F-16 FIGHTING FALCON.svg
View of underside of F-16 during a vertical climb
Testing of the F-35 diverterless supersonic inlet on an F-16 testbed. The
original intake with Splitter plate is shown in the top image
Weapons Storage and Security System vault in raised position holding a B61
nuclear bomb, adjacent to an F-16. The vault is within a Protective Aircraft
Shelter.
Data from ... 阅读全帖 |
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发帖数: 1 | 10 美国将于2月6日发射目前世界上最强大的火箭Space X, Falcon Heavy，可送人类至火
星！
If you have space-obsessed friends, you might have heard the name "Falcon
Heavy" used a lot lately.
Falcon Heavy is a brand new rocket that's set to launch for the first time
ever on February 6, SpaceX announced on Saturday.
The buzz can be attributed to the Falcon Heavy's size: It will be the most
powerful rocket in the world. It's built by SpaceX -- the industry-
disrupting rocket maker started by billionaire Elon Musk.
If you're just catchi... 阅读全帖 |
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s*****V
发帖数: 21731 | 11 伐木工的儿子，做了4个暑假的伐木工才赚取学费，也只上了一个烂校州立。开来美国
搞军工也要考西工大。
此后在TRW工作15年，主持60吨级氢氧火箭发动机的开发。 不满工作中意见不被采纳，
自己在车库里造液体火箭。直到他被ELON MUSK发现，拜为spaceX总师，开发Merlin火
箭发动机。
Mueller was born in St. Maries, Idaho.[4] His father was a logger and wanted
Mueller to be one as well.[5] Mueller compares his story to that of Homer
Hickam, growing up in a hard-working family and going off to be an engineer
instead of following in his father's footsteps.[4] As a kid, he would build
and fly Estes model rockets. He continued to expe... 阅读全帖 |
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p*********e
发帖数: 32207 | 13 请再解释一下
为什么一个"高机动的空优战机"
居然空重比base的su27还高了那么多,而推力却基本没涨?
http://en.wikipedia.org/wiki/Sukhoi_Su-27
SU-27SK
Empty weight: 16,380 kg (36,100 lb)
Powerplant: 2 × Saturn/Lyulka AL-31F turbofans
Dry thrust: 7,670 kgf (75.22 kN, 16,910 lbf) each
Thrust with afterburner: 12,500 kgf (122.6 kN, 27,560 lbf) each
http://en.wikipedia.org/wiki/Sukhoi_Su-30MKI
SU-30MKI
Empty weight: 18,400 kg[86] (40,565 lb)
Powerplant: 2 × Lyulka AL-31FP turbofans with thrust vectoring, 123 kN with
afterburner (27,500 lbf) each |
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az
发帖数: 16686 | 14 http://www.mitbbs.com/article_t/Parenting/31468043.html
6. Choking (one year of age and older)
a. Choking sign: see picture，这个还挺新鲜的，感觉有点用，如果choke了不能
说话，可以做这个动作来告知别人自己choke了。
b. Give upward thrusts into the victim’s abdomen (Heimlich maneuver)
i. kneel or stand firmly behind the victim and wrap your arms around him
so that your hands are in front;
ii. make a fist with one hand;
iii. put the thumb side of your fist slightly above his navel (肚脐) and
well below the breast bone;
iv.... 阅读全帖 |
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t******s
发帖数: 119 | 15 steve tak kin kwan 4 months ago (edited)
katana ( japanese samurai sword) which held by two hands, movements are
powerful (slashing and cutting and some thrusting), yet relatively,
movements are relative big, which might expose oneself large body area
opened up for being attack, swing/ slashing/ cutting movements of the katana
also relatively taken up more time and telegraphed the intentions. Fencing
using thrusting and poking movements with foil, sabre( slashng , cutting as
well), motions a... 阅读全帖 |
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t******s
发帖数: 119 | 16 steve tak kin kwan 4 months ago (edited)
katana ( japanese samurai sword) which held by two hands, movements are
powerful (slashing and cutting and some thrusting), yet relatively,
movements are relative big, which might expose oneself large body area
opened up for being attack, swing/ slashing/ cutting movements of the katana
also relatively taken up more time and telegraphed the intentions. Fencing
using thrusting and poking movements with foil, sabre( slashng , cutting as
well), motions a... 阅读全帖 |
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W*****t
发帖数: 4595 | 17 刚刚学到的一点
空客飞机使用auto thrust的时候，thrust levers不是随着油门的变化而移动的，而是
固定在一个大致等于起飞推力的位置。一旦auto thrust解除，飞行员必须手动调整油
门，否则飞机推力设置马上变成起飞推力。
这个设计没出事就算了，一出事就要被人诟病了。 |
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x****g
发帖数: 342 | 18 With my partner roughly 10 yards behind me, I raise my weapon and engage the
enemy. The size of our enemy is greatly reduced to half the original, but
they still pose much threat, and any careless mistake i make can be fatal to
our survival. As I test the gladiatrices skill and experience cautiously
thrusting the spear at them here and there from a distance, they show me
some experience with sword wielding apparently fought in previous wars and
were most likely captured by the Roman legions in b... 阅读全帖 |
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b*s
发帖数: 82482 | 19 这个解说又瞎说。不是越长越好的:
The experience of World War I saw a complete reversal in opinion on the
relative value of long rifles and bayonets in typical infantry combat
operations.[20][27][28][29] Whether in the close confines of trench warfare,
night time raiding and patrolling, or attacking across open ground,
soldiers of both sides soon recognized the inherent limitations of a long
and ungainly rifle and bayonet when used as a close-quarters battle weapon.[
20][27][28][29] Once Allied soldiers had been... 阅读全帖 |
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n*********2
发帖数: 357 | 20 IS YOUR BIT FIT? Smart condom will rate your sexual performance including ‘
speed of thrusts’ and ‘girth measurements’
Have you ever wondered how many calories you're burning during intercourse?
How many thrusts? The exact girth measurement?
https://www.thesun.co.uk/news/2993797/smart-condom-i-con-will-rate-your-
sexual-performance-including-speed-of-thrusts-and-girth-measurements/ |
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a***k
发帖数: 1038 | 21 I
The way led along upon what had once been the embankment of a railroad. But
no train had run upon it for many years. The forest on either side swelled
up the slopes of the embankment and crested across it in a green wave of
trees and bushes. The trail was as narrow as a man's body, and was no more
than a wild-animal runway.
Occasionally, a piece of rusty iron, showing through the forest-mold,
advertised that the rail and the ties still remained. In one place, a ten-
inch tree, bursting through... 阅读全帖 |
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m******d
发帖数: 177 | 22 看来你在另一贴的话，终于明白里你为什么搞这个“经文查经”。
原来你所谓【神的永生】、【人的永生】的说法是这么来的啊。。。
和合本的翻译还真是害人。看下面的各个翻译，除了和合本，哪个有“永生”里【生命
】的含义？连和合本修订版都改正错误，翻译成【亙古的神】了。。。
(ASV) The eternal God is thy dwelling-place, And underneath are the
everlasting arms. And he thrust out the enemy from before thee, And said,
Destroy.
(Darby) Thy refuge is the God of old, And underneath are the eternal arms;
And he shall drive out the enemy from before thee, And shall say, Destroy
them !
(ESV) The eternal God is your dwelling place, and undern... 阅读全帖 |
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a*****c
发帖数: 3525 | 23 【 以下文字转载自 Military 讨论区 】
发信人: agostic (π-packing), 信区: Military
标 题: (中英文)原子弹下无冤魂：B29飞行员查尔斯•斯韦尼将军1995国会演讲
发信站: BBS 未名空间站 (Wed Aug 15 20:13:42 2012, 美东)
只有记忆才能带来真正的原谅，而遗忘就可能冒重复历史的危险。
One can only forgive by remembering. And to forget, is to risk repeating
history.
学英文是为了更好地了解历史。文章很长，有兴趣学英语同时了解历史的同学，希望耐
心地看完（也可以拷贝下来仔细研读）。不仅仅是学英语，更重要的是学如何写作，如
何摆事实，讲道理，反驳质疑。可以学的东西(中英文)原子弹下无冤魂：B29飞行员查
尔斯•斯韦尼将军1995国会演讲很多，就看你是否能够用心去领悟。这是一篇难
得的informative/historical/linguastic article. Enjoy and welcome to ... 阅读全帖 |
|
a*****c
发帖数: 3525 | 24 【 以下文字转载自 Military 讨论区 】
发信人: agostic (π-packing), 信区: Military
标 题: (中英文)原子弹下无冤魂：B29飞行员查尔斯•斯韦尼将军1995国会演讲
发信站: BBS 未名空间站 (Wed Aug 15 20:13:42 2012, 美东)
只有记忆才能带来真正的原谅，而遗忘就可能冒重复历史的危险。
One can only forgive by remembering. And to forget, is to risk repeating
history.
学英文是为了更好地了解历史。文章很长，有兴趣学英语同时了解历史的同学，希望耐
心地看完（也可以拷贝下来仔细研读）。不仅仅是学英语，更重要的是学如何写作，如
何摆事实，讲道理，反驳质疑。可以学的东西(中英文)原子弹下无冤魂：B29飞行员查
尔斯•斯韦尼将军1995国会演讲很多，就看你是否能够用心去领悟。这是一篇难
得的informative/historical/linguastic article. Enjoy and welcome to ... 阅读全帖 |
|
w*********r
发帖数: 42116 | 25 不是现查WIKI的问题。两个重要参数，你只比较一个，就会有漏洞。
一开始，你用SPECIFIC IMPULSE来说明新火箭多恐怖，提到了推力是旧火箭的１点几倍
，如果燃料一样多的话。数据表明，SATURN V的推力很大，需要１０个RS６８才够。
然后你强调SPECIFIC IMPULSE才是至关重要的因素。可是数据又表明，旧ENGINE一样有
这么大的SPECIFIC IMPULSE。光看这个指标，新ENGINE也不恐怖。
作为一个ENGINE，都给出两个参数，一个SPECIFIC，一个THRUST，发射重量一定了，必
须达到哪个才能反射成功？
RS６８恐怖的地方在于SPECIFIC IMPUSLE和THRUST都大。 |
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c**i
发帖数: 6973 | 26 Harpoon is A/R/UGM-84.
AGM stands for air-to-ground missile; RGM Radar Guided Missile; UGM
Underwater Guided Missile.
(1) Harpoon Block II; Backgrounder. Boeing, undated.
http://www.boeing.com/defense-space
/missiles/harpoon/docs/HarpoonBlockIIBackgrounder.pdf
Quote:
"Weight:
1,160 lb. Air configuration
1,459 lb. ASROC configuration
1,520 lb. TARTAR configuration
1,523 lb. Capsule/canister configuration
"Propulsion: Air-breathing turbojet engine (cruise), solid-propellant
booster
Note:
(a) RUR-5... 阅读全帖 |
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x****u
发帖数: 12955 | 27
The only difficulty involved in increased load is designing a higher thrust
rocket. Saturn-5's thrust is ample for the weight of the Apollo moon lander
. Everything else you mentioned as "difficulty" equally affect any other
moon lander, manned or unmanned. |
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w**j
发帖数: 1032 | 28 The act of murder is rampant in the Bible. In much of the Bible,
especially the Old Testament, there are laws that command that people be
killed for absurd reasons such as working on the Sabbath, being gay, cursing
your parents, or not being a virgin on your wedding night. In addition to
these crazy and immoral laws, there are plenty of examples of God's
irrationality by his direct killing of many people for reasons that defy any
rational explanation such as killing children who make fun of... 阅读全帖 |
|
xt
发帖数: 17532 | 29 那么这一组飞行参数怎么样？
Length: 22.6 m
Height: 5.9 m
MTOW: 34 Ton
Range: 3880 km
Speed: 2 Mach
Max Weapon Load 2.25 Ton (Int.) & 5.75 Ton (Ext)
Thrust Vectoring: With Jet Nozzle (±15 º)
Engine Thrust: 2X1400 kgf
是不是比土鳖的四代五代的牛逼啊？ |
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a*****c
发帖数: 3525 | 30 只有记忆才能带来真正的原谅，而遗忘就可能冒重复历史的危险。
One can only forgive by remembering. And to forget, is to risk repeating
history.
学英文是为了更好地了解历史。文章很长，有兴趣学英语同时了解历史的同学，希望耐
心地看完（也可以拷贝下来仔细研读）。不仅仅是学英语，更重要的是学如何写作，如
何摆事实，讲道理，反驳质疑。可以学的东西(中英文)原子弹下无冤魂：B29飞行员查
尔斯•斯韦尼将军1995国会演讲很多，就看你是否能够用心去领悟。这是一篇难
得的informative/historical/linguastic article. Enjoy and welcome to comment.
(中英文)原子弹下无冤魂：B29飞行员查尔斯•斯韦尼将军1995国会演讲
英文版来源：
http://www.archive.org/stream/smithsonianinsti00unit/smithsonia
Fulltext of Charles W. Sweeney's Hea... 阅读全帖 |
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r***e
发帖数: 2000 | 31 The problem was the pilot pulled the stick when their
was no thrust available from the engines at the time
and the speed was way under take-off/land speed.
Pulling the stick at that speed with no thrust from
engines would have done nothing good but brought down
the airplane.
On another thought, even 137 knots might not be good.
The two other planes which were used in comparison
all landed at on or above 150. |
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z*****4
发帖数: 835 | 32 搜了下wiki，发现除了毛子以外，PLA、NATO还有许多大国小国都有打飞机的历史。
http://en.wikipedia.org/wiki/List_of_airliner_shootdown_inciden
1940s[edit]
Kaleva OH-ALL[edit]
Main article: Kaleva (airplane)
Junkers Ju 52-3/mge "Kaleva" OH-ALL was a civilian transport and passenger
plane operated by the Finnish carrier Aero O/Y, shot down by two Soviet
Ilyushin DB-3 bombers on June 14, 1940, while en route from Tallinn, Estonia
, to Helsinki, Finland.[1] This occurred during the Interim Peace between
Finland and the Soviet Union, t... 阅读全帖 |
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T**********e
发帖数: 29576 | 33
自己家的，9-11以后难道没被fbi监控。
In late 2001, Tom Mueller was sacrificing his nights and weekends to build a
liquid-fuel rocket engine in his garage.
Mueller, a propulsion engineer at Redondo Beach, Calif.–based aerospace
firm TRW, felt like an “unwanted necessity” at his day job. His prolific
ideas about engine design were lost at such a large, diverse company. To
satisfy his creative impulses, he built his own engines, attached them to
airframes and launched them in the Mojave Desert with fellow enthus... 阅读全帖 |
|
发帖数: 1 | 34 发动机
Powerplant: 1 × Pratt & Whitney F135 afterburning turbofan
Dry thrust: 28,000 lbf[671][N 9] (125 kN)
Thrust with afterburner: 43,000 lbf[671][672] (191 kN)
加力推力191KN。 |
|
发帖数: 1 | 35 安-24 所有事故：
1960s
1962
29 July 1962
A MAP Kiev MSZ An-24 (CCCP-46708) overran the runway at Sheremetyevo
Airport following an aborted takeoff.[1]
1965
20 March 1965
An Aeroflot An-24 (CCCP-46764) landed short of the runway at Khanty-
Mansiysk Airport, struck a snow drift and broke up, killing 43 of 47 on
board.[2]
1966
2 February 1966
A United Arab Airlines An-24 (SU-AOB) crashed at Luxor, Egypt during a
test flight.[3]
18 March 1966
United Arab Airlines Flight 749 crashed while a... 阅读全帖 |
|
W***n
发帖数: 11530 | 36 Rahul Patil
Answered Jul 18, 2016 · Upvoted by Muhammad Afsar Malik, 15 years ATCO, 8
years airline economics, National Aviation Policy 2015
I’m not truly qualified or experienced in the aerospace industry, so my
answer is based more on technical specs and anecdotal reports from users (
pilots, technicians). Some amount disparity also remains in application :
fighter/military engines vs commercial.
My verdict? GE.
Rolls Royce alone is nowhere near its former glory, the aero engine industry
has t... 阅读全帖 |
|
发帖数: 1 | 37 HONG KONG -- At 28, Dai Wenyuan quit his job developing artificial
intelligence software for Chinese internet giant Baidu to launch his own
company. It was a smart move: his AI start-up quickly attracted an initial $
4 million investment from Sequoia Capital China in 2015.
Three years later, Dai's company is capturing attention for developing a
medical tool that uses AI to predict whether patients are at risk of
developing diabetes. His company, 4Paradigm, said its accuracy rate was 88%.
Key to ... 阅读全帖 |
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w********2
发帖数: 632 | 38 McKinley Conway, 1920-2011:
Last Flight Home in a Landmark Life
ONLINE INSIDER
McKinley Conway
by JACK LYNE
T
his Mac Conway fellow, you might be wondering, now just who was he again?
Yeah, he's the guy who started Site Selection 'n all, but did he ever do
anything else? I'm kinda in a hurry here, pal. So just tell me who this dude
was like.
Oh, hell, Mac Conway wasn't like anybody. He never followed anyone's
footsteps; he couldn't really. He was too restless a spirit, too hell-bent
on slashing ... 阅读全帖 |
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p*********e
发帖数: 32207 | 40 实际上
al31的函道比是0.6,117s根据wiki的说法,把风扇直径提高3%,从而提高推力
问题是这样一来函道比更大
通过外涵道直接排出引擎的空气流速要比内涵道排出的燃气低很多
因此在飞机超音速的状况下函道比高意味着推力受影响更大
即便你的额定干推力很大,函道比大的话仍可能无法进行超音速巡航
顺便纠正一下,web thrust是指开后燃器的推力,正常说超巡指的是不开加力超巡
对应的是dry thrust. |
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n*******a
发帖数: 862 | 41 这玩意儿动力还是有的吧，：Engines: One Thiokol XLR-11 rocket of 8,000 lbs. (
3,625 kg) thrust; two Bell LLRV optional landing rockets of 400 lbs. (181 kg
) thrust each
跟导弹差不多？ |
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c******k
发帖数: 8998 | 42 你这种人，不调查一下就喜欢胡勒，然后被人扇脸，扇了无数次，脸皮越扇越厚。
On December 8, 2008 Lt Neubauer was piloting an F/A-18D-30-MC Hornet (Lot 12
), BuNo 164017,[4][5][6][3] from VMFAT-101, based at MCAS Miramar. Along
with several other VMFAT-101 aircraft, he was conducting day and night
carrier qualifications (catapult launches and tailhook arrested carrier
landings) aboard the aircraft carrier USS Abraham Lincoln offshore 60 miles
southwest of San Diego.[7] Neubauer was the only crewmember on board the two
-seat aircraft.[3... 阅读全帖 |
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k**0
发帖数: 19737 | 43 还是看看Combat radius再说吧，
F-16C:
1. Empty weight: 8,372~8,710 kg
2. Internal fuel: 3,160 kg
3. Thrust of engine: 23,770 Ib~29,000Ib class
4. Combat radius: 740 nm (with 2,000 Ib bomb*2 + AIM-9L*2 + 1,040 Gal
external fuel)
--> The total fuel of F-16C in this condition is 3,160 + 1,040*3.785*0.8 =
6,309 kg.
======================================================
F-35A:
1. Empty weight: 12,000~12,500 kg
2. Internal fuel: 8,390 kg
3. Thrust of engine: 40,000~43,000 Ib class
4. Combat radius: 600~700 nm ... 阅读全帖 |
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p*********e
发帖数: 32207 | 44 http://www.sukhoi.org/eng/planes/military/Su-35/
"
In terms of engineering, the engines are substantially modified AL-31F
production engines employing fifth-generation technologies. They use a new
fan, new high and low pressure turbines, and a new digital control system. A
provision is made for using a vectored thrust nozzle. The modernization has
increased the engine special mode thrust by 16%, up to 14,500 kgf. In the
maximum burner-free mode it reaches 8,800 kgf.
"
且不说航电上的升级,仅考虑动力,117s发动机相对AL... 阅读全帖 |
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n******r
发帖数: 236 | 45 我纠正一下我的例子，应该只有一吨推力(1000 千克力)，忘了乘重力加速度(~10 m/s^
2)。所以代入公式的是10000 N.
如果你喷的是未加压的冷水，且喷向自由空间，基本上在流体力学上是free jet case,
i.e., the gauge pressure is ~0.你应该计算需要的喷速。
mass rate (m_dot) is 200 kg/s. Thrust T = m_dot*V. So V = T/m_dot = 20*1000*
10/200 = 1000 m/s.这是你需要的喷射速度。
继续分析这个设计，在喷口m_dot = density * V * area A.
如果假设水不可压缩，density 是个常数1000 kg/m^3.
你的火箭喷口面积 A = m_dot/(density*V)=200/(1000*1000)= 2e-4 m^2.
火箭的直径 ~1 cm!!
换句话说，如果你的喷水率固定(m_dot is fixed)，水作为工作物质密度不变(没有爆
燃),thrust = m_dot^2/(density * A).
如果你想保... 阅读全帖 |
|
发帖数: 1 | 46 早在上世纪80年代末，苏联就曾设想过多重可复用的火箭系统。其中最令人印象深刻的
，是以“能源”号超级火箭为母型研制的ГК-175可回收式重型运载火箭。其最大的特
征，在于配备了可独立飞行滑翔降落的助推器组件。在火箭发射以后，全部助推器将在
空中展开机翼，以滑翔的方式着陆返厂。
ГК-175可回收饲重型运载火箭畅想。其主体部分接近一架无人航天飞机，而助推器则
各自独立具备机翼构造
上述手段科幻且炫酷，但存在着相当大的技术风险。而相对简单的，则是自上级70年代
末起就开始构想的可部分回收火箭系统。在上述构想中，火箭只有发动机部分是需可回
收的。在完成任务后，火箭的发动机部分从箭体上分离、气动减速，并在下降到一定高
度后展开降落伞。这时，将会有一架安装了天钩回收系统的飞机从其上方略过，钩住降
落伞将其收回。整个回收过程很类似飞船返回舱【注释：在SpaceX咄咄逼人的攻势下，
ULA考虑采用这个方案，实现下一代运载火箭的部分回收复用】。
那么SpaceX的回收将采用哪一种方式呢？都不考虑。
类似于ГК-175滑翔回收方式，存在系统复杂且的风险。而天钩模式虽然较为可靠，但
也需要一套独立的分离、... 阅读全帖 |
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m*****n
发帖数: 5245 | 47 ☆─────────────────────────────────────☆
thrust (Thrust Jaeina) 于 (Fri Sep 21 23:21:52 2007) 提到:
你还是一边儿歇歇吧。
☆─────────────────────────────────────☆
zlike (最终幻想) 于 (Sat Sep 22 00:04:19 2007) 提到:
天啊，不会吧，不敢相信是你说的。
难道你以为下面的code通不过？
#define double(x) (x++)*(x++)
int main()
{
int x=5;
printf("%d\n",double(x));
}
运行结果给你贴出来了，我觉得可能是misunderstanding...
☆─────────────────────────────────────☆
Thudy (七匹狼之饿狼传说) 于 (Sat Sep 22 00:10:26 2007) 提到:
1是什么意思？这样有什么好处？
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z***e
发帖数: 5393 | 48 每个人，从开始找工作的时候，都会在这个版，也许还有programming版泡上几个月，
这个期间你会知道很多ID，然后，也许你会逐渐发现某些ID对于每个问题的回答都是如
此地精准。
他们也许只说了短短几个字，也许兴致所至会长篇大论，但无论怎样的回答，总是包含
了无穷的奥义。这便有如当年觉远和尚的几句梦话，便让资质平凡的他人穷尽一生去摸
索。
而这些人如果自己开始讨论，更是有如华山论剑，让你领悟到正是因为有这些人的存在
，其他搞IT的只能称为民工。
如果，thrust/goodbug是配得上东邪西毒的名号，那么，包括我的很多人，充其量是彭
连虎的角色。
然而，即便是彭连虎，也会向往着能摆脱民工的称号。
对于阿根廷球员，无论获得何等成绩，马拉多纳永远是无法超越的目标；
对于梅西，即便在今日他也仍然视小罗为世界第一；
某个作家说过：每个男人都是凝视着另一个男人的背影长大。
昔日浪翻云的覆雨剑号称“因能极于情，故能极于剑”，其理相同。当追随着thrust的
背影，offer，便不再是一个困扰。 |
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d**e
发帖数: 6098 | 49 ☆─────────────────────────────────────☆
HorseKing (二逼青年思路广) 于 (Mon Apr 23 21:49:20 2012, 美东) 提到:
我感觉版上有无数学院派的，说白了就是整天盯着算法看的，背题目的。
版上还有几个牛人显然是实用派的，也就是已经在IT领域内工作并有小成/大成的
俺也算是个实用派，每次看到版上发的那些算法题俺就特惭愧，因为完全不懂哇。。。
我既没找过什么KTH，也没用过NLOG，但这似乎并不能阻碍我成为框架师。所以我也不
懂了，一方面吧，我觉得懂算法的都很牛，另一方面有觉得搞算法的似乎理论性都太强
了点。
我很困惑为什么版上就没几个愿意进入我们应用领域的呢？俺承认，这个帖子灰常的无
厘头。
☆─────────────────────────────────────☆
StevenLow (CrossLayer) 于 (Mon Apr 23 21:49:55 2012, 美东) 提到:
马哥牛逼。
☆─────────────────────────────────────☆
yangc... 阅读全帖 |
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d**e
发帖数: 6098 | 50 ☆─────────────────────────────────────☆
yangcheng (牛魔王) 于 (Tue Apr 24 16:57:24 2012, 美东) 提到:
自称做过无数iPhone
问objective C, 语法都不知道，说忘了。
最近做java 。 cloud啊， hadoop啊，
然后问Java
说equals是比较class, 我问她是不是和instaneof 弄混了 她说java没这个关键字。就
是equals()。
然后我还被告知Object 没有wait() method, 只有Thread有。
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danicahu (katelyn) 于 (Tue Apr 24 16:58:13 2012, 美东) 提到:
^_^
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colwell2008 (colwell2008) 于 (Tue Apr 24 17:12:57 2012, 美东) 提到:
难道那些... 阅读全帖 |
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