Odd aircraft queries

[GMascelli]

Shared from USA today.

 

[brien23]

Sounds like the thread's posted on this board.

 

[Sac Arrow]

Re: Question #4

Let's say you're flying from Portland to Sydney. Do you have to take in to account the earth's rotation if your navigation is:

a) GPS?

b) Dead reckoning?

c) How about INS?

 

[MAKG1]

Earth's curvature, yes. Rotation, no. Except for INS.

If your "navigation" were unguided (as in, point and forget), then earth's rotation would be important. From moment to moment, Coriolis and centrifugal forces are not significant when you correct the path from moment to moment.

We have the world's biggest INS in the back of our airplane (well, it's a 2.5m blind pointing telescope -- largely the same thing, even has a star tracker to deal with the inevitable gyro drift), and it has to take the sidereal time into account. That compensates for earth's rotation, and it's annual motion in the orbit around the sun.

Aircraft can't transform to boats? Well, maybe not current airliners, but there is a pretty cool Grumman Albatross parked at San Carlos, and a whole bunch of Lakes at Palo Alto.

 

[Graueradler]

The dimpled golf ball question isn't bad. Isn't that akin to how VGs work. I've participated in the wind tunnel test measuring the drag of a smooth glass sphere vs the drag of the same sphere with sand glued to the leading "edge". The one with sand clearly has less drag.

 

[Sac Arrow]

The dimpled golf ball question isn't bad. Isn't that akin to how VGs work. I've participated in the wind tunnel test measuring the drag of a smooth glass sphere vs the drag of the same sphere with sand glued to the leading "edge". The one with sand clearly has less drag.

But if I'm not mistaken, the purpose of the dimples is not drag reduction, but rather to create a counterflow boundary layer on the underside of the spinning ball to act as a wing, which is what allows it to stay airborne longer.

 

[Sac Arrow]

Earth's curvature, yes. Rotation, no. Except for INS.

If your "navigation" were unguided (as in, point and forget), then earth's rotation would be important. From moment to moment, Coriolis and centrifugal forces are not significant when you correct the path from moment to moment.

We have the world's biggest INS in the back of our airplane (well, it's a 2.5m blind pointing telescope -- largely the same thing, even has a star tracker to deal with the inevitable gyro drift), and it has to take the sidereal time into account. That compensates for earth's rotation, and it's annual motion in the orbit around the sun.

Aircraft can't transform to boats? Well, maybe not current airliners, but there is a pretty cool Grumman Albatross parked at San Carlos, and a whole bunch of Lakes at Palo Alto.

Yes, I mean point and forget when I say dead reckoning. Now, as a practical matter, depending on how you are holding your heading, there are bigger issues to deal with like changing magnetic variation (if you're using a magnetic compass) and of course winds.

INS is a different animal though. From what I understand in researching it, is that because the unit is calibrated and initiated on the ground, it is already in the same inertial plane as that of the earth's surface, which makes it self correcting for the rotation of the earth.

 

[MAKG1]

Earth's surface is not inertial. It is rotating about the polar axis, and about the Sun. Both are detectable with a decent three-axis gyro, though they tend to drift.

It is, however, rather easy to remove from the solution. The limiting factor in its accuracy is the aircraft attitude and heading when the instrument is aligned. It turns out that a small error in the direction of north leaves a leftover rotation that is not hard to detect. We can lose our targets when we don't refine the alignment using the star tracker (it's A LOT more accurate than the attitude indicator, by a factor of a few thousand).

 

[frfly172]

Like the golf ball theory,will have to leave the aircraft out ,during next hail storm,that will give you plenty of dimples.

 

[cgrab]

But the answer to the last question is Yes, when I travel to the beach this weekend I will in fact be flying the plane.

 

[Capt. Geoffrey Thorpe]

The dimpled golf ball question isn't bad. Isn't that akin to how VGs work. I've participated in the wind tunnel test measuring the drag of a smooth glass sphere vs the drag of the same sphere with sand glued to the leading "edge". The one with sand clearly has less drag.

If your airplane was about the same shape as a golf ball and traveled at about the same Reynolds number, it would work.

But, most airplanes are somewhat streamlineish in shape so you don't have the same flow separation problem that you do with a sphere at most angles of attack. At high angles of attack, vortex generators can add energy to the boundary layer and help it stay attached like the dimples on a golf ball. So, sometimes they help, and sometimes they hurt.

 

[Shepherd]

Even my wife howled with laughter over those questions.

 

[asicer]

There are airplanes with dimpled skin but probably not for improved aerodynamics.

 

[AggieMike88]

Folks who ask those questions, I often wonder if their favorite phrases include, "But it has electrolytes!"

 

[weilke]

I have heard the dimpled golf-ball theory as an explanation as to why the Skymaster can fly.

 

[Ted]

I had thought they were experimenting with some paint that would have a similar effect to dimpling golf balls?

 

[AggieMike88]

I've got a few from my business....

Customer: I need a lamp for my car...

AM88: Okay, which one?

Customer: I'm not sure, but my husband said it has red in it.

AM88: Okay, is that for the front or the rear? (yes, I know it's a taillight, but I'm smart alecking)

Customer: Ummm.. I don't know. I'll call you back.

----------------------------

Customer: Do you have a steering pump for my F150?

AM88: Sure, what year of F150 and what color is it?

Customer: It's a 2005 and Silver...

AM88: Well, my inventory computer says I do have one but it's out of a red truck, how about $80 with a lifetime guarantee and I can have it ready in a few hours?

Customer: That's a good price, but I think I need one from a silver truck. I'll call you back.

-----------------------

Customer: I see on Car-Part.com you have a front driveshaft for my 2004 Gr.Cherokee, U-joint style. (rare item, since most of these FDS's are CV jointed)

AM88: Let me verify that for you. In the mean time, how soon do you need it and have you found others out there? (qualifying questions to find out if he's serious about the sale and what my competition might be)

Customer: I've been looking for a week, need it badly, and haven't found one yet.

AM88: Okay, I'm glad you called us. I do still have that. Can you confirm the price you see on your side (my screens show $165, a fair price, but I'm setting him to close at that dollar).

Customer: Sure, I see $165 for that.

AM88: Good... Just give me your name and phone number and I'll write up the order for $165, 6-month warranty, and get you taken care of.

Customer: Wait a sec..... I'm not going to pay that...

AM88: (????!!!!) But you said you needed one quickly, I have it, you saw $165, and you called me.

Customer: I know, but you junkyards are always trying to rip people off and I'm not going to pay anymore than $50.

AM88: You're at $50, I'm at $165 with 180-day warranty. I'll change my price to $120, sold as is, but that's my bottom dollar.

Customer: I thought you said it was a 6-month warranty?

AM88: Okay, $165 with 6-month warranty.

Customer: That's better...... but I'm still not going to pay more than $50.

AM88: Bless your heart sir, and have a wonderful day.

----------------------------------------

Customer: Do you sell parts for Datsuns?

AM88: Not often, but I can find them.... what do you need?

Customer: My mechanic says I need need a twenty-eight ounce steering pump for my 1977 Datsun

AM88: (What the....???) Ummm... I need a bit more info, what type of Datsun?

Customer: Well, he wrote it down for me, let me show you the paper. (hands me the mechanics note)

"Dear Jill. Please go by Denton County Auto Salvage and see if they have what I need to fix your car. Ask them for a 28oz steering pump"

-----------------------------------------

Customer: I have a 1997 F150 and I something but I don't know what it's called. It's on the front of the engine and goes round and round.

AM88: Oh, one of those! Sure, I got that... usually we get $85, but if can come see me today, I'll discount to $60.

Customer: Wonderful! I'm just up the street and I'll be right there.

(Turns out he needed a fan clutch that I had 12 of at $40 each.)

----------------------------------------

AM88: Yes ma'm, I have your part

Customer: How much is it please?

AM88: We'll in the past it was a tad over one million dollars, but let me see what how big of a discount I can arrange...

Customer: What??!?!?? I'm not going to pay that much --click--



And it goes on... There are so many people I encounter that likely are just barely lucky enough to know which pedal to stomp on and what to do with the big round thing in front of them.

Makes me wonder if I've been warped into a bad version of an Abbott and Costello routine

 

[MAKG1]

Yeah, but have you ever had a customer come in looking for a 710 cap?

 

[Zeldman]

I heard my first one today while doing a guided bear viewing trip. We have some spectacular views of hills that look like mountains and still covered with snow. So after we landed on the beach, right next to the ocean, one client asked me, "What elevation are we at?"

 

[flyingron]

Hey, I used to drive one of those 28 ounce cars.

 

[rwellner98]

The dimpled golf ball question isn't bad. Isn't that akin to how VGs work. I've participated in the wind tunnel test measuring the drag of a smooth glass sphere vs the drag of the same sphere with sand glued to the leading "edge". The one with sand clearly has less drag.

http://www.discovery.com/tv-shows/mythbusters/videos/dimpled-car-minimyth/

tl;dr a dimpled car got better mileage.

 

[AggieMike88]

Yeah, but have you ever had a customer come in looking for a 710 cap?

Not yet. But I do have fun at the big box part stores pulling that prank.

 

[AggieMike88]

Re-reading this thread, I'm very much reminded of Bill Engval and "here's your sign".

 

[overdrive148]

I found these comments last year off of Yahoo after an SR-22 crash.

Al 16 hours ago
So they just escorted him to his death? I guess as long as he flew away from the White House it was every man for himself, huh.

Anthony Popovich 11 hours ago
they just flew alongside the unconscious pilots' plane & watched it crash into the ocean? What kind of cold and cruel people do we have flying these military planes? Yeah, we see him. We'll just wait till he crashes then go home. If they weren't so callous, all of them, not just the F-16 pilots, they should have tried to help the stricken pilot. Maybe try to rescue him from his plane from another plane or helicopter. They should have some sort of laws to keep military pilots away from the elderly or young children.

J. V. DZUGASHVILI 16 hours ago
Why wasn't the Cirrus Airframe Parachute System (CAPS) deployed by the F-16 pilots?
They could have easily initiated a soft water landing by the Cirrus SR22.

J. V. DZUGASHVILI 17 hours ago
If there were two F-16s, why not deploy a net between them to catch the plane, once it ran out of fuel?
Then they return to shore and hand it off to a rescue copter

Andrew F 16 hours ago
It is surprising that there are not nets strung between large aircraft that can sweep up smaller aircraft that have problems.

WhiskeyBum 12 hours ago
Couldn't one of them have climbed out , and into his plane to take the controls , or at least knocked on his window to wake him up ?
They were sent up there to kill him , and they did , through doing nothing .

Sunshine 15 hours ago
Wait, what? Didn't they build the f-16 in the 1970s? How old is our Air Force?

chevfan_1 18 hours ago
During times like this why don't they send the f22. Much faster and more capable plane.

H2O 4 hours ago
We have a restricted airspace over Washington D.C.? THAT is news, but considering those that supposedly work there are always ignoring the American people it just confirms that it IS another country and not part of the U.S.

flowerc 16 hours ago
This is sure an expensive rescue and not to mention the cost of the F-16s to monitor this pilot, was he drunk, in any case there sure have been a lot of people flying small planes; having accidents a lot! These people should not have a license to fly!! there should be a new rule about getting your pilot license, it should be more hours and they should be evaluated every year!!
this is getting ridiculous!

Kate 2 hours ago
This is why humans should not fly. If mankind was meant to fly in the sky like that we would have wings. When the old gods return they will smite down all those sinners who dare mock them.

John 17 hours ago
So a plane flying from Wisconsin to Virginia is only require to have 1 pilot and no co-pilot? I am surprised there are not more planes falling from the sky everyday.

Yahoo 1 hour ago
They assume he was dead, but what if he was just asleep? Too bad they don't have horns on those jets.

boby b 16 hours ago
really nothing could have been done to save him!!! Maybe a hook or something, a parachute, or I don't know, something. I am really dead scared of small planes. There is nothing you can do if something bad happens. Maybe some adjustments like a eject seat be incorporated to them in future. convalescents to family, and fighter pilots, I guess they are already sad, so do not feel bad, it happens. Just a lesson for future.