Aviation Questions & Answers

[Antartis]

I have searched the internet for answers on aircraft and found no answers.

And I thought it might be a good idea to create a topic with questions and answers.

So anyone who has a question on air to answer questions others and be informed. :book:

 

1) I noticed that several aircraft in the nose part, such as the Russian front wheels have tubes which I think are the soil hydraulic brakes (MiG-23, 25,27,29 Sukhoi 22,24,25,27). But the West (F-14, F-15, F-16, F/A-18, F-22 Ef2000) have nothing to nose piping components. Why this difference?

 

Mig-21 nose wheel brake

 

F-16 nose wheel (no break)

 

2)Another question, when the planes fly and leave the exhaust as we can the weather radar to "see"?

 

 

 

3)... (I have other questions, but I forgot redrawing) :P

Edited May 28, 2011 by Antartis

[5by5]

Hi there, good thread!

 

1. Several Russian military aircraft have their nose gear equipped with a wheel braking system.

This is in keeping with the general cold-war design philosophy of having their aircraft deployable from short/unprepared fields. The Americans did not design similar requirements into their tactical aircraft. (Presumably the A-10s landing speed/distance required, is low enough not to require the additional benefit of nose wheel braking)

2. I think your question is whether contrails are detectable with a commercial onboard weather radar. The short answer is no.

The weather radar in commercial aircraft is designed to detect high water content in cloud i.e. rain. It is not very good at detecting ice crystals (which contrails are composed of).

It is possible to use weather radar to detect other aircraft though. Although it takes a bit of patience to get the radar tilt angle just right!

[Antartis]

1) Yes, I think so too.

 

2) Well understood for my second question. Interesting for the radar. Thanks for your response. :)

[Antartis]

(noob questions)

 

1) Why canards reduces the stealth and why not reduce horizontal tail the stealth?

 

2) Why not have all helicopters (Apache, Mi-28 etc...) eject seats as the Ka-50?

[nscode]

Not sure, but:

 

 

Wings sort of hide the tail, while canards "stick out" and increase visible front surface. not sure how it stands on other models

[Antartis]

Not sure, but:

 

Wings sort of hide the tail, while canards "stick out" and increase visible front surface. not sure how it stands on other models

 

Got it.

 

Thanks buddy, I will look it. :)

 

(It is not so convincing. But anyway.)

Edited June 4, 2011 by Antartis

[EtherealN]

2) Why not have all helicopters (Apache, Mi-28 etc...) eject seats as the Ka-50?

 

It's just not considered useful in most cases. Apaches usually fly low-and-slow, and ejecting might actually be more dangerous than just trying to keep the bird upright until impact and let the airbags handle you.

 

Another possible cause you be potential issues when operating as a group - you'll send rotor blades heading in all directions, and if you work as a tight Apache fire team this could mean you'll take your mate down with you. (Though I doubt that this is a real reason.)

[Conure]

Awesome thread :-)

 

Real nooby question here...A boeing 747 is cruising at 36k feet when suddenly both engines cut out. They cannot be restarted. Is it possible for the plane to land, or will it drop out of the sky?

[Avilator]

Awesome thread :-)

 

Real nooby question here...A boeing 747 is cruising at 36k feet when suddenly both engines cut out. They cannot be restarted. Is it possible for the plane to land, or will it drop out of the sky?

 

It will glide. Whether or not a suitable airport is within gliding distance is another matter altogether. Also, the chances of all of the engines failing at once are extremely small. You are more likely to die by drowning in your own bathtub.

 

Just a note: a 747 has 4 engines, so the word "both" is a bit out of place if you want to refer to all of the engines.

[Conure]

It will glide. Whether or not a suitable airport is within gliding distance is another matter altogether. Also, the chances of all of the engines failing at once are extremely small. You are more likely to die by drowning in your own bathtub.

 

Just a note: a 747 has 4 engines, so the word "both" is a bit out of place if you want to refer to all of the engines.

 

Hi there, thanks for your reply. I meant all rather than both, sorry! Basically the question was less about the reliability of the engines and more about the capabilities of the airframe at high speed/high altitude without engines!

[nscode]

Wings keep you in the air, not the engines. If you have enough altitude to convert into forward speed, and that speed takes you far enough to a suitable landing surface, you have a chance of survival.

 

On the other hand, in jets that need lots of speed to produce lift, eg. MiG-21 or F-104, the distance that you have available without the engine (glide ratio) is so low that recommanded thing to do is just make sure the aircraft doesn't hit anyone on the ground and eject.

[acerus77]

A good Story about a gliding Tubeliner is the one of the Gimmli Glider.

[Conure]

A good Story about a gliding Tubeliner is the one of the Gimmli Glider.

 

That's incredible - that nobody was seriously injured is absolutely amazing!

[EtherealN]

There's also the world's fastest (and worst) purpose-built glider:

 

The space shuttle performs re-entry almost completely without the use of engines: it will initiate it's re-entry through a de-orbit burn (slowing it down to below orbital speed), and from that point on it's a glider.

 

And since you have a simulator available, I'd very much suggest that you try it out: take your A-10 in a clean configuration up to angels 30 or something like that, and then shut both engines down. Point yourself towards a field some distance away and you'll note that you will get considerable farther away than you might initially think - though obviously not as far as a plane purpose-built for that kind of flight (competition grade gliders will have a glide ratio if handled well up to 60:1, meaning that from angels 30 it could glide ~300nm. (Though it achieves those glide ratios at such low airspeeds that doing it at angels 30 isn't practical.) The trick for doing the gliding as an emergency maneuver is to find the most effective airspeed - in FC2, if you fly an F-15, you'll be looking at somewhere around 220KCAS and obviously do not deploy flaps or gears unless you really have to - and drop all weapons. I'm not entirely certain about the best glide speed of the A-10, but I could check it out in the -1 if you like.

Edited June 4, 2011 by EtherealN

[mikoyan]

Not sure, but:

 

 

Wings sort of hide the tail, while canards "stick out" and increase visible front surface. not sure how it stands on other models

 

what is the difference between regular delta wing an diamond shape wigs in aerodynamic terms?

 

I did notice that the j-20 has the wing far back; what is the benefit? if you look at the rafale and the grippen; they both have the wing closer to the center of the airplane; why is that? to reduce drag while turning?

Last 2 questions:

Are the f-15, su-27 and mig-29 equipped with a stick shaker like commercial airplanes?

 

I read a while a go that the su-27 flight control system don't correct inertias for the pilot like an f-16 would do; like for example while rolling; the pilot has to stop the roll by applying opposite aileron deflection to stop the roll; the f-16 does it automatically for the pilot; the same applies for the pitch at a lesser degree. Now my question is; are newer flankers like for example the mki using a more advanced flight control system that helps with the inertias?

[nscode]

Don't know about Su-27, but there was a comment a while ago from a MiG-29 pilot testing LockOn - things aren't like there IRL. He said that while rolling, if you put the stick back in center, the plane stops rolling on the spot.

It also has a stick limiter that will push back if you're about to go over alpha limit. All you need to do to override it is to pull harder :=)

Edited June 5, 2011 by nscode

[Avilator]

That's incredible - that nobody was seriously injured is absolutely amazing!

 

Personally, what I find more amazing is the fact that the plane flew out a couple of days later and was still in use years afterwards!

 

what is the difference between regular delta wing an diamond shape wigs in aerodynamic terms?

 

From some quick reading of my aircraft design book here is my understanding. The delta wing is constructed as a very highly tapered unswept wing. This requires a very thick wing root to fit all of the structure, but it ends up lighter(so does the fuselage) because it is stiffer. A tapered wing will be thinner at the root, but it will require less total area than a delta wing sized for the same aircraft and conditions, particularly landing speed. This is because of the tail configuration usually used with a delta(tailless), which does not allow for large flaps because they would be very far aft of the center of gravity, and cause an unacceptable amount of pitch down moment. For this reason, the delta will also require a much higher angle of attack(and a higher pitch angle at touchdown) to generate the same amount of lift. This causes aircraft with a delta configuration to generally lose more energy in a turn than other aircraft.

 

 

I did notice that the j-20 has the wing far back; what is the benefit? if you look at the rafale and the grippen; they both have the wing closer to the center of the airplane; why is that? to reduce drag while turning?

 

Where the wing is placed has pretty much everything to do with the pitch stability of the aircraft. If the center of pressure (where the lift acts) is forward of the CG, the aircraft will be unstable, and not return to a previous flight condition when upset. If you put a horizontal tail forward of the CG (a canard, like the J-20), you can control it with a computer and deal with the instability in that manner. The big advantage of this is that both surfaces provide a force upwards in level flight, and so trim drag is reduced over a rear-tailed aircraft, where the tail pushes downwards.

 

 

That's the short version. Ask away if you have questions, and anyone feel free to correct me if need be. :thumbup:

[159th_Falcon]

A good Story about a gliding Tubeliner is the one of the Gimmli Glider.

 

That's incredible - that nobody was seriously injured is absolutely amazing!

 

Don't forget, that was an Airbus, which are all equipped whit an RAT.

(Ram Air Turbine) in the case all engines stop working, it can be deployed.

Basicly it is a windmill generating some electrical and hydraulic power.

 

Boeing on the other hand does not have a similar device, at least not on an 747. Though apparently the engines windmilling generates enough hydraulic pressure to keep the plane flyable.

[acerus77]

Don't forget, that was an Airbus, which are all equipped whit an RAT.

(Ram Air Turbine) in the case all engines stop working, it can be deployed.

Basicly it is a windmill generating some electrical and hydraulic power.

 

Boeing on the other hand does not have a similar device, at least not on an 747. Though apparently the engines windmilling generates enough hydraulic pressure to keep the plane flyable.

From Wikipedia: On 23 July 1983, Air Canada Flight 143, a Boeing 767-200 jet, ran out of fuel at 26,000 feet.....

The decreasing forward motion of the aircraft also reduced the effectiveness of the Ram Air Turbine (RAT), making the aircraft increasingly difficult to control because of the reduced power being generated.

So i guess it was not an Airbus :music_whistling:

[EtherealN]

Last I checked a 767 is not a 747... ;)

[nscode]

I think the point was that it wasn't an Airbus :)

[acerus77]

Last I checked a 767 is not a 747... ;)

what? But its a Boeing! :music_whistling:

[Avilator]

Boeing on the other hand does not have a similar device, at least not on an 747. Though apparently the engines windmilling generates enough hydraulic pressure to keep the plane flyable.

 

That statement is correct. Every other Boeing has a RAT. I've also read that the 747-800 has one.

 

If all of the flight engines failed (and there was still some fuel), the APU could be started to provide electrical and hydraulic power.