Airplane quiz 1! - AR15.COM

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Posted: 12/9/2018 3:03:04 PM EDT

You are the flight engineer of a B52 flying towards Guam with a max load of bombs in the internal bays when all of your engines fail and will not restart. The pilots quickly set the auto pilot to the best glide airspeed and All three of you calculate the glide distance and all get the same answer - 30 miles. You are currently 30 miles from the runway threshold.

One pilot says "Its going to be real close, we should drop all the bombs into the ocean so the plane will be lighter and glide a bit farther. "
The other pilot says "what flight school did you go to? Dropping the bombs will actually reduce glide distance, we should keep them."

Both pilots turn around and look at you to break the tie. If your goal is to maximize glide distance, do you tell the pilots to drop the bombs or keep them?

Posted: 12/9/2018 4:10:38 PM EDT

[#1]

Salvo the weapons. Lower weight = longer glide distance.

eta And never fly with the second pilot again.

Posted: 12/9/2018 4:13:27 PM EDT

[#2]

I believe the procedure is to jettison bombs in an emergency anyway...depending on the type of emergency.

Jettison the bombs and pilot 2, as well.

I can't see how having the weight of the bombs would increase glide distance unless they put the plane into a better center of gravity and trim condition, but it should be entirely possible to trim it to the same condition whether it's loaded or empty.

Posted: 12/9/2018 4:17:37 PM EDT

[#3]

Crash land with a full load of ordnance? Is this a trick question?

Posted: 12/9/2018 4:19:47 PM EDT

[#4]

Dump the ordnance.

An unpowered landing with a bunch of bombs is a bad thing. Sctew up the landing they might go BOOM.

Posted: 12/9/2018 4:22:08 PM EDT

[#5]

You can't land with it loaded! It could put the island off balance and tip it over!

Posted: 12/9/2018 4:28:25 PM EDT

[#6]

Drop enough ordinance to achieve optimal wing loading for LD Max.

Posted: 12/9/2018 4:31:09 PM EDT

[#7]

Keep them and keep the plane clean as long as possible. Don't open the doors and increase drag, the additional weight could actually help depending of the glide characteristics. Dump them once you know you've got the runway made. So both.

Posted: 12/9/2018 4:40:13 PM EDT

[#8]

Opening the bomb bay doors would increase drag. Keep em.

Posted: 12/9/2018 5:16:47 PM EDT

[#9]

I’d wonder how drunk we all were when we let a flight engineer on a buff. Then I’d eject while we were in the envelope

Posted: 12/9/2018 7:14:57 PM EDT

[#10]

First off, thirty miles of glide distance isn’t nearly enough to reach a runway 30 miles away.

Second, gliding in with a load of bombs is irresponsible.

Third, opening the bomb bay doors will cause lots of drag, shortening your glide considerably.

Jettison the bombs in a safe area, try to relight engines until It got down to a few thousand feet and then prepare to ditch. If Sully can do it, then so can I.

Forgetting the effect of opening the bomb bay doors, I’m thinking a lighter plane would glide further?

Happy to be proved wrong on that one, but I do know it would stop quicker, so dump most of the fuel while your at it!

Posted: 12/9/2018 7:32:14 PM EDT

[#11]

Under the options proposed - Keep the Bombs.

Weight does not affect L/D - just the speed you fly best L/D.

With the bombs you will be touching down sooner, but the extra weight will help the aircraft penetrate better.

Just don't crash...

In reality - Drop them, and prepare for ditching. Margins are too close.

Posted: 12/9/2018 7:42:35 PM EDT

[#12]

Quote History

Quoted:
Salvo the weapons. Lower weight = longer glide distance.

eta And never fly with the second pilot again.

View Quote

Posted: 12/9/2018 10:46:46 PM EDT

[#13]

Quote History

Quoted:
Under the options proposed - Keep the Bombs.

Weight does not affect L/D - just the speed you fly best L/D.

With the bombs you will be touching down sooner.....

View Quote

We have a winner! Others said keep them, but not explicitly why.

More specifically, weight does not change the glide angle of a glider. When you do the math weight cancels out and this proves true in the real world.
Weight does increase the airspeed and descent rate at which you get the best glide angle(thus you will land sooner), but that angle is constant no matter the weight of the aircraft.

If you open the bomb bays to dump the bombs drag will go up significantly, so dumping the bombs will actually shorten your max glide distance.

Cross country racing gliders have water ballast tanks to add weight and increase the airspeed at which they get their best glide angle, thus arriving at their destination faster. The glide angle and range remains the same. Prior to landing they dump the water to reduce weight(and thus airspeed) to make landing safer and have a shorter rollout.

Posted: 12/11/2018 6:52:51 AM EDT

[#14]

Find the asshole that didn't fill up the fuel tanks and stick a knife in him..........

Posted: 12/11/2018 7:42:30 AM EDT

[#15]

Gravity sucks.
Drop the bombs.

Posted: 12/11/2018 7:46:32 AM EDT

[#16]

Quote History

Quoted:

We have a winner! Others said keep them, but not explicitly why.

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Explain this: Lift counteracts gravity. If the plane weighs more, their must be more lift to counteract the sink rate. The only way to get more lift is to have more forward velocity. Since the plane has no power, that's impossible.

So, no power = no added lift = faster sink rate.

How am I wrong about that?

Posted: 12/11/2018 9:31:28 AM EDT

[#17]

Quote History

Quoted:
The only way to get more lift is to have more forward velocity. Since the plane has no power, that's impossible.

How am I wrong about that?

View Quote

First you post nonsense twice in a row in an educational post rather than editing your first post.

Second your statement above is so ridiculous I can't even believe you typed it. "The only way to get more lift is to have more forward velocity". Do you really believe that? If so, how can an airplane climb, cruise, and descend all at the same airspeed?

Third "since the plane has no power it can't go faster". I can't tell if you're really that clueless or if you're trolling.

Fourth you're too intellectually lazy to do a quick internet search for "weight glide ratio airplane airspeed" which would have produced on the first page of results:
https://en.m.wikipedia.org/wiki/Lift-to-drag_ratio
An executive summary that confirms the answer I posted.

It's things like this that make me wonder why I even bother reading this website!
I can't just leave your post alone because somebody might read it since it's the last one and think it's true.

Posted: 12/11/2018 9:40:54 AM EDT

[#18]

Quote History

Quoted:

First you post nonsense twice in a row in an educational post rather than editing your first post.

Second your statement above is so ridiculous I can't even believe you typed it. "The only way to get more lift is to have more forward velocity". Do you really believe that? If so, how can an airplane climb, cruise, and descend all at the same airspeed?

Third "since the plane has no power it can't go faster". I can't tell if you're really that clueless or if you're trolling.

Fourth you're too intellectually lazy to do a quick internet search for "weight glide ratio airplane airspeed" which would have produced on the first page of results:
https://en.m.wikipedia.org/wiki/Lift-to-drag_ratio
An executive summary that confirms the answer I posted.

It's things like this that make me wonder why I even bother reading this website!
I can't just leave your post alone because somebody might read it since it's the last one and think it's true.

View Quote

He was asking a legitimate question. No need to jump down his pants and start scratching. Not everyone is a flight engineer.

Posted: 12/11/2018 11:32:39 AM EDT

[#19]

Quote History

Quoted:

We have a winner! Others said keep them, but not explicitly why.

More specifically, weight does not change the glide angle of a glider. When you do the math weight cancels out and this proves true in the real world.
Weight does increase the airspeed and descent rate at which you get the best glide angle(thus you will land sooner), but that angle is constant no matter the weight of the aircraft.

If you open the bomb bays to dump the bombs drag will go up significantly, so dumping the bombs will actually shorten your max glide distance.

Cross country racing gliders have water ballast tanks to add weight and increase the airspeed at which they get their best glide angle, thus arriving at their destination faster. The glide angle and range remains the same. Prior to landing they dump the water to reduce weight(and thus airspeed) to make landing safer and have a shorter rollout.

View Quote

We are flying in a B-52 and not a plane designed to be a glider. I would prefer the bombs gone.

Posted: 12/11/2018 3:15:10 PM EDT

[#20]

Quote History

Quoted:
Find the asshole that didn't fill up the fuel tanks and stick a knife in him..........

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Every pilot knows that "E" means "Enough."

Posted: 12/11/2018 4:43:00 PM EDT

[#21]

Keep the bomb until the landing is in hand.

Same reason gliders carry ballast

Posted: 12/12/2018 1:14:34 AM EDT

[#22]

Thank you for your reply.

For a second I lost conficence in our ARFCOM pilots.

Speed changes, rate of descend changes but glide distance remains identical. You just get to the crash site faster...

This was meant in response to Morgan321.

Posted: 12/12/2018 9:21:27 AM EDT

[#23]

Eject.

Posted: 12/12/2018 6:08:59 PM EDT

[#24]

nvm

Posted: 12/12/2018 7:12:28 PM EDT

[#25]

B-52’s don’t have flight engineers but if they did, it would increase the chances of survival greatly.

Posted: 12/12/2018 11:36:37 PM EDT

[#26]

I’m not crash landing a B52 with 70K lbs of bombs on board.

Posted: 12/13/2018 12:11:00 AM EDT

[#27]

Quote History

Quoted:
Opening the bomb bay doors would increase drag. Keep em.

View Quote

Technically this is the correct answer. Best glide, if flown at a specific Angle of Attack, will result in the same glide path regardless of weight, all other factors being equal. Opening the doors increases drag, regardless of weight, requiring a steeper glide path to compensate.

Caution - Aerodynamics/math follows:

For a given angle of attack, the ratio of lift:drag will be the same. Flying at a higher speed will increase both lift and drag by the same fraction. E.G. if you fly 10% faster, you'll get 21% more drag (1.1 x 1.1 = 1.21). So if your aircraft weighs 21% more with bombs than without, you'll fly 10% faster, generating 21% more lift and 21% more drag. The descent angle required for gravity to account for that extra drag will be identical, however. The equivalent thrust generated by your descent angle is equal to sin(descent angle) * weight. Since weight and drag are proportional, the descent angle is the same for both cases.

Note - if your bombs are EXTERNALLY carried, then you're better off jettisoning them, along with the pylons they are mounted on...

Mike

Posted: 12/13/2018 12:26:28 AM EDT

[#28]

Every time I have an engine failure and dumping the load is an option, I dump. Unless I'm going to ditch in mud, then I keep the load for the rear cg advantage. But I'm not in a B52 and rarely over 50' when it quits.

Posted: 12/15/2018 1:47:14 PM EDT

[#29]

Quote History

Quoted:

First you post nonsense twice in a row in an educational post rather than editing your first post.

Second your statement above is so ridiculous I can't even believe you typed it. "The only way to get more lift is to have more forward velocity". Do you really believe that? If so, how can an airplane climb, cruise, and descend all at the same airspeed?

Third "since the plane has no power it can't go faster". I can't tell if you're really that clueless or if you're trolling.

Fourth you're too intellectually lazy to do a quick internet search for "weight glide ratio airplane airspeed" which would have produced on the first page of results:
https://en.m.wikipedia.org/wiki/Lift-to-drag_ratio
An executive summary that confirms the answer I posted.

It's things like this that make me wonder why I even bother reading this website!
I can't just leave your post alone because somebody might read it since it's the last one and think it's true.

View Quote

Wow. Way to be a complete ____.

Lift is generated by air flowing over a wing. Without forward velocity you get no lift (but you knew that.)
Lift counteracts gravity. (but you knew that.)
In level flight, a loss of power causes an airplane to descend. (but you knew that.)

And listen up, ____... this thread started with a question - YOUR QUESTION. Are you so arrogant that when someone with less knowledge than you posts an incorrect answer you have to berate them?

I even ASKED you to help me understand.

What a ____.

Posted: 12/15/2018 3:46:14 PM EDT

[#30]

Cut out the personal attacks. This is not a suggestion.

Posted: 12/18/2018 8:42:07 PM EDT

[#31]

Jettison bombs. Eject if the runway will not be made. With bombs on board, a heavier aircraft will have to maintain a greater angle of attack to maintain altitude with the given thrust setting, whatever it may be.

Maybe don’t jettison if it produces an unfavorable CG, with the fuel on board?

(In short, the heavier aircraft with bombs on board is making more lift, therefore more drag, which will reduce gliding distance)

Posted: 12/19/2018 12:49:42 AM EDT

[#32]

Quote History

Quoted:
(In short, the heavier aircraft with bombs on board is making more lift, therefore more drag, which will reduce gliding distance)

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Incorrect. Explained above.

Posted: 12/19/2018 1:29:22 AM EDT

[#33]

Quote History

NM.

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Posted: 12/19/2018 1:42:09 AM EDT

[#34]

Quote History

Quoted:
Incorrect. Explained above.

View Quote View All Quotes

View All Quotes

Quote History

Quoted:

Quoted:
(In short, the heavier aircraft with bombs on board is making more lift, therefore more drag, which will reduce gliding distance)

Incorrect. Explained above.

I’ll be damned, I am humbled.

Posted: 12/19/2018 1:49:59 AM EDT

[#35]

whats the SOP? do that.

Posted: 12/20/2018 9:48:16 AM EDT

[#36]

Seeing as how you’ll have to put the aircraft in a landing configuration at some point prior to touchdown, and considering engine driven hydraulic pumps will either be dead or severely degraded (windmilling may still produce some presdure), you will most likely be forced to use alternate gear extension/flap extension procedures, which take longer, and will require putting the aircraft in landing configuration sooner, thus increasing drag sooner, which means you will not make the runway.

Eject.

What does the dash 1 say?

Posted: 12/21/2018 4:21:35 PM EDT

[#37]

Quote History

Quoted:
Eject.

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This! Get as close to recovery assets as possible and punch.

Posted: 12/21/2018 4:35:47 PM EDT

[#38]

simple Find nearby ISIS aircraft carrier,

Drop nose & Fly into said ISIS aircraft carrier with full bomb load.

Enjoy your eternity McFeasting with the Immortals in Valhalla!

Posted: 12/21/2018 5:52:18 PM EDT

[#39]

Keep the bombs? Spoken like true egotistic pilots who have no regard for the crash crews on the ground. If you're willing to look for it, a Phantom had a hung 500 lb bomb when it crashed and caught fire. A number of folks on the ground were killed as was the crew of the Husky LBR helo.

Posted: 12/25/2018 8:17:53 PM EDT

[#40]

Quote History

Quoted:
Keep the bombs? Spoken like true egotistic pilots who have no regard for the crash crews on the ground. If you're willing to look for it, a Phantom had a hung 500 lb bomb when it crashed and caught fire. A number of folks on the ground were killed as was the crew of the Husky LBR helo.

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lol, OP, you really should have said this was a physics geared question and not an air safety/ morals question.

Back to the physics though, since the margin is slim as far as glide distance, being a glider pilot, I would dive that puppy into ground effect at maneuvering speed once I get ~800ft agl to gain some distance. Who knows how far a loaded B-52 would go in ground effect, but it would be fun to find out!

Here is a video of a glider using ground effect to advantage

https://www.youtube.com/watch?v=dsgrI74jJek

Posted: 12/26/2018 6:29:10 AM EDT

[#41]

Weight does not effect glide distance, only the glide speed, you’ll get to said point faster but you won’t go further or vise verse.

Posted: 12/27/2018 12:13:45 AM EDT

[#42]

Quote History

Quoted:
Weight does not effect glide distance, only the glide speed, you’ll get to said point faster but you won’t go further or vise verse.

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Okay, I have about 55 hours. Rookie question.

Presuming that you glide faster while heavier, if you pitch to best glide speed would you not go further?

Posted: 12/27/2018 7:36:33 AM EDT

[#43]

Quote History

Quoted:
Okay, I have about 55 hours. Rookie question.

Presuming that you glide faster while heavier, if you pitch to best glide speed would you not go further?

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No, because the best glide speed changes based on weight. As explained above, the best possible glide ANGLE is constant, only the airspeed at which you get that best glide angle changes.

So when heavier you must glide faster to get the (same) best glide angle as when you are lighter.
If you fly the same descent angle you will fly the same distance but arrive faster if you are heavier(and thus must fly faster). This is why cross country race gliders are ballasted - to get to the same destination faster than if they were lighter.

Posted: 12/27/2018 12:06:52 PM EDT

[#44]

Quote History

Quoted:

No, because the best glide speed changes based on weight. As explained above, the best possible glide ANGLE is constant, only the airspeed at which you get that best glide angle changes.

So when heavier you must glide faster to get the (same) best glide angle as when you are lighter.
If you fly the same descent angle you will fly the same distance but arrive faster if you are heavier(and thus must fly faster). This is why cross country race gliders are ballasted - to get to the same destination faster than if they were lighter.

View Quote

Gotcha, thanks for the explanation.