Well, he is an experienced pilot who single handedly won WW2 and the Cold War, so he should know his way around a jet engine.

lol. i was just thinking the same thing guys

Also, since he wrote a dissertation called "Aerodynamics and Airplanes" I assume he is an expert on the ENTIRE field, since a specific topic was beneath him.

The short answer: No.

@ Glorious93:
I have never claimed that.

how about the long answer?

I had a suspicion that would be the case, because if it weren't people would design their way around it, for instance by not mounting the engines where they do.

Clearly a jet engine has some effect on the way the air flows around the wings though. What is it?

Long answer? Okay.

Aircraft designers often put the engines in/under the wings because the airflow over the wings is the cleanest in terms of shock waves. The primary lifting component of the aircraft is the wings, which require a slow-moving airflow below and a fast-moving airflow above. The suction zone from the jet engines does not include the airflow on either the top or bottom of the wing. Although a large volume of air is required for the jet engine to function, the suction zone is actually relatively small. If you look closely, the intake is actually in front of the leading edge of the wing, thus excluding the wing from the suction zone. The loss of intake behind the wing does not matter. As long as there is airflow directly above/below the wing, the wing can function.

For those of you with shorter attention spans, I wrote a summary:

The suction zone of the jet engine does not include the wing, allowing an adequate amount of air to pass above/below the wing. Wings can function as long as there is airflow above/below the wing.

http://en.wikipedia.org/wiki/Podded_engine

Does the outlet have some sort of effect being normally under the wing, or is it just directed away?

Hooray! diplomat1824 contributed positively to the Forum!

Now if he'd only find that quote he attributed to Obama.....

@ TheGhostmaker:

Do you mean exhaust when you say "outlet"?

@ jbalcorn:

That quote came from the book "How to Win a Fight With a Liberal" by Daniel Kurtzman. It was not attributed in the book.

Yes, I do.

Diplomat, unattributed quotes in books aren't real quotes, they are propaganda.

The quote is "Conservatives stand for what they believe in. Liberals stand for anything."

--President Obama

I can picture him saying that.

I feel I have addressed the aircraft question. Good day to you all.

How about the exhaust from the jet? Is that just directed away from the wing?

Do you fly helicopters?

Can we please not drag every post down into political bashing session?

Regarding planes and jet engines and wings, I know there are some models that have the engines at the back of the plane rather than on the wings. But the under the wing seems to be more common. Anyone know if there is a downside to having the engines in the back?

@diplomat: _The quote is "Conservatives stand for what they believe in. Liberals stand for anything."
--President Obama
I can picture him saying that. _

And I can picture Rush Limbaugh saying "When I'm on Oxy, I like little boys". But I wouldn't claim he actually said it and use it in an arguement.

So you took an unattributed quote from a book that purports to teach you how to fight with Liberals and used it to support your argument? Don't you claim to have a PhD? If you used an argument like that in your Dissertation defense, any real review would have rejected you immediately. So I reject your quote as fabrication until you find it correctly attributed.

"Anyone know if there is a downside to having the engines in the back?"

It looks dumb. =)

The tailpipe extends beyond the trailing edge of the wing.

So far, your questions can be answered by a photo of a 737 and basic intuition.

Chrispminis, I do not fly helicopters. I have friends who do, and I ride in them every now and then. Why?

...even if the tailpipe was in front of the trailing edge of the wing, the sheer velocity of the exhaust gases would prevent the wing from being damaged or disrupting airflow.

"So far, your questions can be answered by a photo of a 737 and basic intuition."

That's lucky for you, isn't it then?

Tailpipe!? It's hardly a tailpipe. I believe the proper term is exhaust nozzle. I would think a PhD who did a dissertation on Aerodynamics and Airplanes would know that...

http://farm1.static.flickr.com/78/160345595_7d0d18abac.jpg?v=0

@Alderian - Anyone know if there is a downside to having the engines in the back?

Downsides:
There's a lot more engine noise transferred into the cabin.

The wings generate lift which tends to bend them upwards, the weight of the engines counteracts this, so they don't have to be as strong in order to resist this bending force if the engines are on the wings - they do have to be stronger in a different way because they have to transfer the engine thrust to the body of the plane.

The body of the aircraft has to be strong enough to transfer the thrust from the engines through the entire body of the plane. When the engines are on the wings that extra strength isn't needed: stronger == heavier.

It's called a tailpipe.

@Thuc:
Do you have an advanced, non-trivial question?

Tsk, tsk, tsk, Diplofool.

I disagree

You know, I just jumped in here because I was curious what the answer is to, and I have to admit: Diplomat has been nothing but courteous and stuck to the matter at hand, and many others are trying to pick a fight.

You guys should, perhaps, not throw some many stones if your dwelling are also comprised of transparent silicon

Aliens: Surely when the thrust comes from the engines on the wings, it still must be transferred across the plane?

diplomat. To me that photograph in my last post shows that the exhaust is underneath the wing

This one:

http://farm1.static.flickr.com/78/160345595_7d0d18abac.jpg?v=0

If the tailpipe was in front of the trailing edge of the wing, the sheer velocity of the exhaust gases would prevent the wing from being damaged or disrupting airflow.

I copied and pasted that from my own earlier post. I would encourage you to read the entire thread before posting.

I had read that. I was just pointing out that the tailpipe doesn't extend beyond the trailing edge.

"Do you have an advanced, non-trivial question?"

The short answer: No.

Is the long answer Nooooooooooo?

Okay. Unless anybody else has any questions, please be courteous and allow this thread to fall off the bottom.

@The Ghostmaker - "Surely when the thrust comes from the engines on the wings, it still must be transferred across the plane?"

I thought that's what I said in the last part of the second paragraph ("they do have to be stronger in a different way because they have to transfer the engine thrust to the body of the plane") or have I missed your point?

I was saying that therefore, "The body of the aircraft has to be strong enough to transfer the thrust from the engines through the entire body of the plane. When the engines are on the wings that extra strength isn't needed" Isn't the case, because you still need the strength, just in different places.

But the airframe of a wing-based propulsion system has to be stringer from a drag perspective (wings, and therefore engines, are more forward and essentially pull the bulk of the body along) than from a crumple perspective (engines at the rear push the body forward). Also, the wings themselves require different structural support, not only for the difference in the gravitational pull of the mass (body pulls center down, engines balance that out somewhat) but also in the push/pull configurations. Engine wings put forward stress where the wing connects to the fuselage, where as fuselage mounted engines put a drag stress on the wings. That is why delta and variable wing configurations work so well for fuselage engines. They provide more lift area while reducing drag as the more raked wing reduces pressure buildup on the leading edge.

@ SpeakerToAliens: "The wings generate lift which tends to bend them upwards, the weight of the engines counteracts this, so they don't have to be as strong in order to resist this bending force if the engines are on the wings"

However, aircraft also spend quite a bit of time on the ground, and during those times, the wings do not "bend upwards" and counteract the weight of the engines. The wings have to be strong enough to bear the full weight of the engines over a prolonged period of time, for example if an aircraft is mothballed or undergoing major repairs.

But when mothballed/in repair, they can prop up the wings with additional supports. However, the sheering forces of the engines dragging the wings forward while the fuselage want sot remain behind are even more extreme than the weight of the fuselage hanging on the wings. The optimal configuration for reducing stress at joints is a three engine design with one on each wing and one where the tail connects to the fuselage. This reduces overall stress by spreading the thrust between wings and fuselage. The wings reduce the crushing force caused by the "push" engine at the rear, and the rear engine reduces the horizontal shearing force caused by the wings trying to pull the fuselage along.

@Jamiet99uk - Of course the wings and body have to be able to take the static weight of the aircraft. That's a given.

When being serviced (more than a count the wings and kick the tyres service anyway), we usually prop planes up on stands, high enough to cycle the landing gear.

If its a major service we often take the engines off too, to use as spares. Planes undergoing a major services tend to get "Christmas Tree'd" as a source of spares. An engine (or anything else) sitting around not being used for any length of time is a waste of money. The cost of removing components to use as spares is usually a lot less than the cost of buying stuff to keep as spares and then sticking them a store room.