Aircraft Pic & Vid Thread

[tous]

15 minutes ago, janice6 said:

I'm sure any decent aeronautical engineer from early on, could see the obvious appeal to minimal drag and maximum lift.  The devil was in the control details.

The XP-79 had one flight that ended up in boxes of small pieces.

5 minutes ago, kerbie18 said:

I've been told the ejection seat is only slightly better than the crash.

The modern Martin-Baker ejection system is a wonder, it is virtually a small spacecraft.

Not only can one eject at zero-zero (zero velocity, zero altitude,) but regardless of attitude, even if the aircraft is inverted, the seat will turn you up right so the chute deploys properly.

The nylon descent beats riding the metal to the smoking hole.

Martin-Baker.  One of the few things the British got right.

Edited August 11, 2019 by tous

[janice6]

Just now, tous said:

The XP-79 had one flight that ended up in boxes of small pieces.

The modern Martin-Baker ejection system is a wonder, it is virtually a small spacecraft.

Not only can one eject at zero-zero (zero velocity, zero altitude,) but reagardless of attitude, even if the aircraft is invereted, the seat will turn you up right so the chute deploys properly.

The nylon descent beats riding the metal to the smoking hole.

Martin-Baker.  One of the few things the British got right.

I read that the primary difficulty with a flying wing was that with some oscillating up/down maneuvers, the aircraft would simply go nose down with little time for recovery.

As far as I know, 5 avionics computers mitigated this in the most recent effort.

[kerbie18]

2 minutes ago, tous said:

The XP-79 had one flight that ended up in boxes of small pieces.

The modern Martin-Baker ejection system is a wonder, it is virtually a small spacecraft.

Not only can one eject at zero-zero (zero velocity, zero altitude,) but reagardless of attitude, even if the aircraft is invereted, the seat will turn you up right so the chute deploys properly.

The nylon descent beats riding the metal to the smoking hole.

Martin-Baker.  One of the few things the British got right.

Well, damn. Glad I never took that ride.

[tous]

11 minutes ago, janice6 said:

I read that the primary difficulty with a flying wing was that with some oscillating up/down maneuvers, the aircraft would simply go nose down with little time for recovery.

As far as I know, 5 avionics computers mitigated this in the most recent effort.

Here's the basic problem: how do I change the pitch of an aircraft and keep it under control?

Traditional cylinder stuck on an airfoil aircraft control pitch by raising or lowering the back of the cylinder, via elevators.   I have a nice, efficient, predictable moment.

Now, get rid of the cylinder.

Now, the wing has to control pitch, but where is my nice, predictable moment?

Does the wing know where it is?  Do my flight surfaces perform the same way at any angle of attack?  If my wing stalls, how does my wing recover?

And, anyone that says, Glue some canards on it, gets a beatin'  

That's simplistic, but the heart of the problem.

Edited August 11, 2019 by tous

[janice6]

2 minutes ago, tous said:

Here's the basic problem: how do I change the pitch of an aircraft and keep it under control?

Traditional cylinder stuck on an airfoil aircraft control pitch by raising or lowering the back of the cylinder, via elevators.   I have a nice, efficient, predictable moment.

Now, get rid of the cylinder.

Now, the wing has to control pitch, but where is my nice, predictable moment?

Does the wing know where it is?  Do my flight surfaces perform the same way at any angle of attack?  If my wing stalls, how does my wing recover?

And, anyone that says, Glue some canards on it, gets a beatin'  

That's simplistic, but the heart of the problem.

Thank you, a most excellent explanation.

[Eric]

 

[janice6]

1 minute ago, Eric said:

 

A good landing is when you walk away from it.

A great landing is when the aircraft can be used again.

[tous]

40 minutes ago, janice6 said:

Thank you, a most excellent explanation.

In my mind, it's always about which forces are present, which ones can I use and which ones are going to use me?

 

I keep telling young'uns, science and engineering is the most fun you can have with your clothes on.

Rabbi does it nekkid.

Edited August 11, 2019 by tous

[janice6]

1 hour ago, tous said:

In my mind, it's always about which forces are present, which ones can I use and which ones are going to use me?

 

I keep telling young'uns, science and engineering is the most fun you can have with your clothes on.

Rabbi does it nekkid.

I'll confirm that!

When my compatriots at work were watching the first moments of the Iraq war, the exclamation that went up was, "Sonofabitch!  It all worked!!!"

"...engineering is the most fun you can have with your clothes on...."

 

[tous]

So, you've seen Rabbi engineering nekkid?

[Dric902]

1 hour ago, tous said:

In my mind, it's always about which forces are present, which ones can I use and which ones are going to use me?

 

I keep telling young'uns, science and engineering is the most fun you can have with your clothes on.

Rabbi does it nekkid.

If you don’t have a vertical stabilizer....doesn’t something have to act as a control surface

 

.

[janice6]

6 minutes ago, Dric902 said:

If you don’t have a vertical stabilizer....doesn’t something have to act as a control surface

 

.

 Yes, all on the wing.  Split ailerons (sort of).

[tous]

34 minutes ago, Dric902 said:

If you don’t have a vertical stabilizer....doesn’t something have to act as a control surface

 

.

Most wings will fly straight without  a vertical stabilizer and remain stable as long as the lift is the same along the entire surface.  Asymmetric lift will usually result in roll, not yaw.

We can affect yaw a few different ways besides a vstab and rudder.  The V-tail arrangement, such as the Beech Bonanza and the F-117  comes to mind

Horizontal and vertical stabilization in one package.

With multiple engines, we can use asymmetric thrust to affect yaw, but that doesn't work well.

And as 6 of janice notes, one can use split ailerons such as those featured on the B-2 Spirit.

No one has yet figured out a really good way to do it yet.

Unlike a nice vstab and rudder, with the other systems, when things go bad they go bad fast and recovery is often not possible.

 

Edited August 11, 2019 by tous

[Dric902]

12 minutes ago, tous said:

Most wings will fly straight without  a vertical stabilizer and remain stable as long as the lift is the same along the entire surface.  Asymmetric lift will usually result in roll, not yaw.

We can affect yaw a few different ways besides a vstab and rudder.  The V-tail arrangement, such as the Beech Bonanza and the F-117  comes to mind

Horizontal and vertical stabilization in one package.

With multiple engines, we can use asymmetric thrust to affect yaw, but that doesn't work well.

And as 6 of janice notes, one can use split ailerons such as those featured on the B-2 Spirit.

No one has yet figured out a really good way to do it yet.

Unlike a nice vstab and rudder, with the other systems, when things go bad they go bad fast and recovery is often not possible.

 

Can the thrust vectoring or manipulation accomplish the stabilization. Probably by wire as the touch needed would be slight but nearly constant 

.

Edited August 11, 2019 by Dric902

[janice6]

2 minutes ago, Dric902 said:

Can the thrust vectoring accomplish the stabilization. Probably by wire as the touch needed would be slight but nearly constant 

.

My guess is that thrust vectoring is wonderful when coupled with the other control surfaces. 

When you use thrust vectoring alone to compensate, you run the risk of hysteresis problems.  Forgive me but my language is electronics not avionics.

What I'm trying to say is that you may have a problem in that the change in the thrust vector is slower to accomplish than the moment of the aircraft.

I mean that the thrust directional change may be chasing the attitude change, or visa versa.  In any event without damn near instantaneous correction, you may make the problem worse.  

[tous]

6 of janice has nailed the problem with thrust vectoring.

First, I need enough energy in the system to counter inertia and momentum in the change in vector.

Unlike pitch and roll, yaw doesn't involve the wing and lift, so to point the nose left or right, I need to overcome the inherent stability of the airfoil and then use more energy to make it rotating on the Z axis.

That requires energy right now or a steady and experienced hand on the  controls, and since I don't have big control surfaces with air flowing over them, we need to create the force somewhere else, usually the propulsion system.

 

Note how difficult it was for astronauts and the amount of training they had to move a spacecraft around with reaction jets.  Too little and you aren't ponted the right way; too much and you spin in a circle; too, too much and the jets don't have the energy to overcome the momentum and you spin forever.

 

Good question, amigo.

See how much fun this is?

[Dric902]

7 hours ago, tous said:

6 of janice has nailed the problem with thrust vectoring.

First, I need enough energy in the system to counter inertia and momentum in the change in vector.

Unlike pitch and roll, yaw doesn't involve the wing and lift, so to point the nose left or right, I need to overcome the inherent stability of the airfoil and then use more energy to make it rotating on the Z axis.

That requires energy right now or a steady and experienced hand on the  controls, and since I don't have big control surfaces with air flowing over them, we need to create the force somewhere else, usually the propulsion system.

 

Note how difficult it was for astronauts and the amount of training they had to move a spacecraft around with reaction jets.  Too little and you aren't ponted the right way; too much and you spin in a circle; too, too much and the jets don't have the energy to overcome the momentum and you spin forever.

 

Good question, amigo.

See how much fun this is?

Alright...let your imagination run loose, if we designed Apollo right now.

What would we do differently?

 

.

[janice6]

11 hours ago, tous said:

6 of janice has nailed the problem with thrust vectoring.

First, I need enough energy in the system to counter inertia and momentum in the change in vector.

Unlike pitch and roll, yaw doesn't involve the wing and lift, so to point the nose left or right, I need to overcome the inherent stability of the airfoil and then use more energy to make it rotating on the Z axis.

That requires energy right now or a steady and experienced hand on the  controls, and since I don't have big control surfaces with air flowing over them, we need to create the force somewhere else, usually the propulsion system.

 

Note how difficult it was for astronauts and the amount of training they had to move a spacecraft around with reaction jets.  Too little and you aren't ponted the right way; too much and you spin in a circle; too, too much and the jets don't have the energy to overcome the momentum and you spin forever.

 

Good question, amigo.

See how much fun this is?

Thanks for the explanation.  

[tous]

6 hours ago, Dric902 said:

Alright...let your imagination run loose, if we designed Apollo right now.

What would we do differently?

 

.

We would take advantage of VLSI (Very Large Scale Integration -- making big things that work into small things that work better.)

My spacecraft has two major limitations:  how much space do I have and how much power do I have?

VLSI solves a lot of those problems with much smaller components that require less power, now I can stuff even more goodies into the same space with the same power budget.

But, this is the elephant in the room.  So far, space flight requires that I use 85 - 95% or my vehicle just to get the danged thing out of Earth's gravity well.  I keep the 5% and throw the 95% away.

That drastically limits how big and how heavy my 5% can be.

 

The future of space travel has to be the construction of spacecraft in space so I can keep 80% of my vehicle for useful work, not just the ride from dirt to vacuum.

 

The Lunar Orbiting Platform - Gateway (LOP-G) is the first attempt to construct useful components in lunar orbit and transport them to the lunar surface and go back for more.  Now, just the transport vehicle has to worry about the lunar gravity well.

I won't see it, but the young'uns will.

 

Another problem with space flight is that there is no stuff in space, no fricition, thus, no drag, basically, no brakes.

If I accelerate my spacecraft to ten meters per second and navigate to a place, I just can't throw out an anchor when I get there.  The only way to slow down and park is the same way I sped up: the propulsion system  I need to turn my spacecraft around and using propulsion, slow the craft rather than accelerate it and that theoretically means that in order to slow from ten meters per second, using the same energy that sped me up,  to a stop, I have to begin decelerating halfway there.

This is commonly referred to as turn over.

See what you guys started?  I can talk about this stuff all day, every day.

Dang it, now I need a nap.

[tous]

But, before the nap.

Most folk consider that we sent a spacecraft with squishyware to the Moon and got the warm, pink  parts back to Earth safely as the zenith of engineering.

For me, it was the engineering that resulted in the LRV (Lunar Roving Vehicle -- Moon buggy) to fold up and fit into an impossibly tiny space in the LEM (Lunar Excursion Module.)

I have seen mock-ups* of the LRV and the LEM and the space where the LRV was stowed.  What they did was pure FM.

That was gee whiz engineering at its finest.

Well done, lads.

 

* obviously, the only way to see an LRV or LEM that went on a mission is to go to the Moon.  They left them there.

[Dric902]

16 minutes ago, tous said:

But, before the nap.

Most folk consider that we sent a spacecraft with squishyware to the Moon and got the warm, pink  parts back to Earth safely as the zenith of engineering.

For me, it was the engineering that resulted in the LRV (Lunar Roving Vehicle -- Moon buggy) to fold up and fit into an impossibly tiny space in the LEM (Lunar Excursion Module.)

I have seen mock-ups* of the LRV and the LEM and the space where the LRV was stowed.  What they did was pure FM.

That was gee whiz engineering at its finest.

Well done, lads.

 

* obviously, the only way to see an LRV or LEM that went on a mission is to go to the Moon.  They left them there.

Why could we not put a payload into orbit to be picked up by an empty (er) crew module? Prestaged

we would still need the thrust equivalent since the payload is the same, just spread out over two or more vehicles, but the engineering for the heavy payload is less complex as it does t need atmosphere or escape modules, control systems, etc

 

.

Edited August 11, 2019 by Dric902

[tous]

Good choice, but lifting anything out of Earth's gravity well is very expensive.

One immediate problem with the LOP-G is that for the foreseeable future, the raw materials to build components in lunar orbit have to come from Earth, just as you describe.

At some point, raw materials can be had either from the Moon or by mining asteroids, but for now, if we want ti there, we have to start with it here.

That is just an engineering problem.

Never tell us that it can't be done.

[Dric902]

15 minutes ago, tous said:

Good choice, but lifting anything out of Earth's gravity well is very expensive.

One immediate problem with the LOP-G is that for the foreseeable future, the raw materials to build components in lunar orbit have to come from Earth, just as you describe.

At some point, raw materials can be had either from the Moon or by mining asteroids, but for now, if we want ti there, we have to start with it here.

That is just an engineering problem.

Never tell us that it can't be done.

Until some kind of anti gravity is developed, it’s gonna take X to reach Y.

When we begin (optimist that I am) mining for energy (hydrogen/oxygen from electolysis) or Helium 3 for transport and use on Earth. Even the mining and processing equipment will have to be “orbited”to begin.

Its a long slow curve of efficiency and cost/return analysis. But it is definitely going the right direction.

 

.

 

[janice6]

2 hours ago, Dric902 said:

Why could we not put a payload into orbit to be picked up by an empty (er) crew module? Prestaged

we would still need the thrust equivalent since the payload is the same, just spread out over two or more vehicles, but the engineering for the heavy payload is less complex as it does t need atmosphere or escape modules, control systems, etc

 

.

As said, the problem is the absolute weight lifted is significantly less than the weight necessary to lift it.

Chemical rockets will always be a hinderance, but so far we haven't discovered any viable options.  So far.

Remember that the most amazing technological marvels weren't predicted in advance.  For the most part, Computers for example, burst upon the scene without much preliminary build up. 

I suspect that at some point, some bright individual will simply say, hey, look, I can lift this object with just a little power!!!!!!!!!  At this point, mankind will be on their way to everywhere.

But I don't see it as a goal achieved by a prolonged effort to perfect it over significant time.  It will be a means discovered overnight.  God help me be here to see it come to fruition!

[Eric]