Misc. Qs about Airplanes

QUOTE: Originally posted by hou_ge2000 What would happen, if flying on a jet at crusing alt. and speed, the airplane door get opened?

Your hair would get really messed up.

QUOTE: Does airplane landing gear have drives? or does the plane taxi using the thrust from the engines directly?

They taxi from the thrust of the engines

QUOTE: Is there a Mach 3 aircraft now?

Sure, the SR-71 attained those speeds easily.
The F-15 is a Mach 2.5 aircraft.

Mike

1) Rapid de-compression and structural failure, resulting in crash.

2) Using thrust from the engines, steering by nose wheel steering.

3) Yes. SR-71 still being used by USAF. NASA turned theirs over to the AF. Who knows what the skunk works has flying now in tests.

4) By the time the exhaust heat hits the grass, it has cooled as much as 500%. The grass contains moisture which also prevents it from burning. If exhaust hits for a long time, it will dry it out and catch it on fire. It would take it several minutes for it to do this. Most grass is kept away from taxi ways for this reason.

Other than the SR-71, a few other aircraft have manager Mach 3 or higher: the Space Shuttle, the X-15 (although that's an assisted take-off vehicle), the XB-70 Valkyrie and the MiG-25. Not sure if the MiG-31 is Mach 3 capable..? If so, it's still flying today, along with the -25 and the SR-71.

if the cabin pressure fell to that of the air outside then it may be possible to open a door in flight, otherwise you would have to be the Hulk to open it, as the pressure would hold the door in place.
Most, if not all, airliner doors open inwards first thus assuring the pressure in the cabin plugs the door in place.

on aircraft like the Herc, sometimes the ramp/door locks have been known to fail and the escaping air pressure sounds like a 12 gauge going off on a small room (reliably informed).
the aircraft then dives for a safe altitude, usually anything less than 10,000 ft..

the MLG do not have drives, its all hot air.

Runways do burn from jet exhaust.
Many airfields do not allow harriers to hover / STOVL as the exhaust has ignited the runway in the past - if you notice at airshows they always hover high and away from the runway thus avoiding grass / runway fires.
I once saw a 4 ship of phantoms take off from Ascension at night .
It looked like someone was hosing flame onto the runway, but it didnt catch fire (retardant in the tarmac mix?)

as for MACH 3, the list is ever dwindling.
No more blackbird (I believe it was killed again), no more foxbat (well very few flying) and I dont know if the MiG31 was Mach 3 ( I think its only 2.5)
Like the Concorde, the golden age of aviation is dead and the industry is now run by beancounters, long may they rot in hell !

Don't know if it would count, but the D-21 Drone was also capable of Mach3 at 80,000 ft. Most of the Mach3+ aircraft are now out of service, or on their way out. The Air Force is currently working on a project to produce a bomber capable of near-orbital Mach 14, but that's not supposed to happen until 2034 or so.

I recall some time back that some aircraft I don't remember actually had tire spin-up motors in order to reduce tire wear at touchdown. Anybody recall anything about that?

Dont forget that a lot of older planes didnt have nosewheel or tailwheel steering. They steered using brakes and differential power. Want to go left, give it some left brake and right power. Kinda like steering a dozer or tank. Planes without nosewheel steering are often called nosedraggers. I recall one of the flight crew from the B-29 FiFi talking about taxing to the runway and the airport groundcrew trying to direct the pilot along the nice gentle painted white guideline. The crewman said the ground guy got a little perturbed when they wouldnt follow his direction. Instead they "drove" almost straight up to where the runway started, hit right brakes and left power to swing the big bomber toward the end of the runway.

While on the subject of B-29's , they were pressurized, but were almost always depressurized while over enemy territory. There are many instances where the side gunner blisters popped out during pressurized flight almost sucking the gunner out with it. I have a picture of just such an occurance. You can see the gunner dangling outside of the B-29, he was hauled back in though!

Not much goes faster than Mach 2 because it's not very practical in an atmosphere unless your a spy plane (thus the SR-71) or just in need to show off. There are very few cases anymoe where an intercepter needs to get from point A to B by going Mach 2+.

I say "not practical" because it uses too much feul and limits menuverabliity. What is probably more key in a dogfight is acceleration and menuverability. Thus the trend of military aircraft in the latest generation (think F-18) not to go as fast as planes of old.

Re Decompression in flight.
This was a question in one of my examinations and the result is rather frightening.
1) Unbelted pax could be blown out of the A/C
2) If at a high Flight Level human blood can boil!
3) The body would expell any internal gasses or other things.
4) I cant remember any more! Structural damage could/would occur if it was a door that let go. A crash is not always the inevitable result of said damage.
The pilot would decend to below 10,000ft.
The pilot and second dickie would earn all their money and bonuses that day!
Dai

Hey guy's here's the scoop of Decompression, Remember Paine Stewart?, the Golf Pro, well back in 1999 he was killed when the Learjet he was in lost compression at altitude the first thing is that the whole cabin would fog out, and all of the occupants will have their Ear drums rupture and get a instant Mygrain Headache for about 15 seconds then Hypoxia will set in and the occupants will lose conchance and pass out then away, if a door or window will blow out the same as above but massive air flow will go out the opening only until the cabin will equalize in pressure and that will take about 30 seconds to 1 minute and then no airflow out only in from slip stream, and all heat will literally go out the window, so if you don't die from Hypoxia then Hypotherma will get you, also remember back in the late 80's the 737 Hawaiian Airlines plane lost about 1/3rd of the roof in flight yes there was structral damage but the plane didn't crash it made it back to the airport minus a few people that was not belted in but the plane was repaired and back in the sky's, also the on airlines the door can't be opened in flight because the door needs to pulled in then rotated out with the interior pressure higher the outside pressure it would be humanly impossible to open the door, but on some Corperate A/C the door just drops and that could blow out but on airliners it'll never happen, and for objects hitting the plane causing the door to open at altitude is like winning the Power Ball,
as for the plane moving itself on the ground it's the thrust from the engines,
and for an A/C going Mach 3 the SR-71 and some think the F-22 are the only M3 A/C alot of people also think the MiG 25 is a M3 plane but it becomes very unstable at M2.75 and only if your nuts will a pilot take the plane over that speed, it was found out that the F-15 is faster then the MiG 25 and more stable at High Speeds
and for the grass by runways & taxiways because the engines are high above or within the pad the plantlife isn't damaged that much, a great Airport to check out is Orlando International they have grass & scrubs right next to the pads and they are greener then ever

The questions have been well answered so I'll just add that when the RCAF got their first jet fighters, DH Vampires, which had what would be called today a low slung chassis, there were indeed numerous grass fires until they learned not to park them too near the tarmac edge.
Bruce

Another thing about these non-steerable aircraft... the pilots of the B-17 also use this technique to steer the plane (aside from the tailwheel), but an "instructional movie" by boeing for pilots recomended that you not pivot on the wheel as this may burst the tire (and that'll ruin your day pretty quick)... Apparently you had to make sure that the pivoting wheel moved a bit when turning. it must've been the same for most bombers.

What i want to know is if the B-17 was ever used in lowlevel bombing runs like the famous B-24s that raided the Ploiesti oil fields... i've never seen any pictures of that. And another thing. there are buttons on the steering yoke of the B-17. what were those used for? pickle button? Intercom?

Most buttons on vintage steering yokes were radio PTT, auto pilot disconnect, and maybe an intercom PTT. That would be about it as I believe there was no electric trim. I don't know if the B-17 pilot had an 'emergency jettison' button as he would have to open the hydraulic bomb doors first.
Maybe someone else can be more specific.
Bruce

If a commercial jetliner at cruising alt or speed suddenly run out of fuel or had all engines fail, does it automatically implies death to all passengers?

QUOTE: Originally posted by hou_ge2000 If a commercial jetliner at cruising alt or speed suddenly run out of fuel or had all engines fail, does it automatically implies death to all passengers?

I would say yes. Those things don't glide all that well. [:0]

another thing you have to remember is that when the nose wheel is free castering, the brakes and engines are the only way to steer. You learn real quick to think of steering it like a boat, caus unlike a car it ain't going to happen at once but a second or two after you really want it too. And if you turn too sharply at a low speed the nose wheel will cock over and lock in place - so someone gets to get out and kick it back around so you can try again - Been there, done that, got the T-shirt

Air Canada ran an airliner out of fuel at cruise once and the intrepid crew proceded to glide it to a landing in Gimli Manitoba. Everbody lived but the local store had a run on underwear that day.
The aircraft is famous in the fleet today as "The Gimli Glider."
Airtransat did the same thing mid atlantic and also pulled off a hard but safe landing.

A note about rapid decompression - my Dad flew B-29s for a bit after the war (he was a P-47 fighter pilot during, and decided to try something new). The B-29 had two pressurized compartments fore and aft, with the unpressurized bomb bay between them. To get thru, there was a tunnel over the bomb bay, connected to the two pressurized compartments. You went thru on a trolley on your back, pulling yourself along on an overhead rope.

One time a guy was in the tube when one of the rear observers' bubbles blew out at altitude. The guy was shot down the tube like a cannonball and slammed into an observer's chair at the aft end. I think he lived thru it, but was pretty seriously hurt. Everybody else put their O2 masks on and were fine. Nobody got sucked out like Goldfinger.

MikeV - The glide ratio of most jet airliners is better than most gliders (14 to 1 - 14 feet forward for every foot of altitude lost) - In the late 60s a major airline of the time had a 707 deadheading (no passengers) from KC to LA. At 1 am local, over Las Vegas at 42,000 ft, scheduled to start descent into LA and with little traffic around, the flight crew asked ATC if they could try an experiment and ATC approved. They wanted to determine how far they could get before they descended to 10,000 ft. They chopped all 4 throttles, configured the slats and flaps for best lift condition, adopted best glide angle and made it all the way to LA TCA with no power. The pilot claimed they could have made a landing but ATC had to route them around after entering the TCA because of traffic conflicts at low altitude.
Shrikes - I read somewhere that B-17s participitated in skip bombing during the battle of the Bismark Sea - I have seen pictures of a B-17 practicing skip bombing on a target hulk in Australia supposedly in that time period.

As one can see from the other replies you can glide any aircraft and a smoking hole is not the inevitable outcome of running out of fuel. Having said that, such a situation puts a whole new paradigm smack in the flight crew's lap which many are not properly trained to deal with. Air Canada was very lucky in that the pilots had time in smaller aircraft and remembered the flying basics, but they were very much test pilots that day as there was no literature on board regarding power off stall speeds, best glide speeds, etc.

Boeing later ran that scenario in their simulators and virtually every other pilot crashed the sim.

Bruce

qmiester, I believe that I read about that also. If I remember correctly they were trying skip-bombing because high-level bombing of ships did not work as well as the high-level bombing of a stationary target. I don't think that the skip-bombing technique was very successful with the heavies though and that is why you mostly only hear about medium bombers carrying out the task. I will try to do a little research for more info.

Jerry

I'd lay odds you couldn't glide an F-104
I once read that for every malfunction listed in the pilot's manual, the solution was "eject"

I thought most modern aircraft could not glide well at all: F-16, F-22, Rafale, Typhoon, Su-27,... They are designed as 'unstable' aircraft, no?

QUOTE: The glide ratio of most jet airliners is better than most gliders (14 to 1 - 14 feet forward for every foot of altitude lost)

WRONG
The Jantar std 3 (SZD-48-3) has a glide ratio of 40:1 and the Edelwes C30S is 36:1
Gliders (sailplanes) are designed to glide commercial airliners are not.

QUOTE: I thought most modern aircraft could not glide well at all: F-16, F-22, Rafale, Typhoon, Su-27,... They are designed as 'unstable' aircraft, no?

Correct for fighters. Stability = poor manuverability therefore they are designed to be a little unstable to get an increase in manuverability. This was a lesson learned in WWI. The Fokker triplane (actually a quadplane) had 50%+ more wing area than a comparable biplane which made it a fast climber and very stable but it was a mediocre dogfighter at best and a bear to land. The Sopwith Triplane had the same wing area as a Sopwith Camel eace wing being 33% shorter. It provide more lift but maintained some instability necessary for dogfighting.

QUOTE: Originally posted by djmodels1999 I thought most modern aircraft could not glide well at all: F-16, F-22, Rafale, Typhoon, Su-27,... They are designed as 'unstable' aircraft, no?

I dunno... I figure that there must be a way to lock the control surfaces to generate the best lift. i mean, you won't be doing manouvers once your engine's flamed out... what i hear that is bad for most modern fighters is total power loss. there aren't many analog back-up instruments on most western fighters. (unlike the russians who looove them dials and needles).

After a malfunction of the gun in early testing of the F-104 I could have sworn the pilot had to glide to a landing. Wasn't that on 'Wings'.

Here's something between an idle question, and a light stab at expanding my knowledge: What's the largest amount of engines used successfully on any type of aircraft?

I'd like to think it was the late-model B-36's (with 10), but maybe there's a crazy experimental model out there I have no idea exisits! :)

Grass would never burn, Jet exhaust will 1- bend the blades of grass back so that it just blows over the top. 2- it contains water vapour, jet fuel when burned with compressed air contains a small amount of water vapour. 3- a good wind will blow out a fire- Full Throttle

shrikes and qmeister,

In Flying Fortress: the illustrated biography of the B-17s and the men who flew them by Edward Jablonski in the Chapter "Turning the Tide" (on pages 74-75) they talk about skip-bombing techniques but don't say how successful the bigger bombers were at it. It only makes the general statement that the Japanese "suffered terribly from these devices," (para-frag bombs, also dropped from low levels over parked planes and other targets, and skip-bombing) "objected to these methods..." I have some other books that I can check in but I knew that I could find it quick in this one.

Jerry