wrighbrothers
Topic Author
Posts: 1807
Joined: Wed Jul 27, 2005 8:15 am

Over Wing Engine?

Wed Aug 11, 2010 4:41 pm

Hi all

I'm currently reading 'Handling The Big Jets' by D.P.Davies (a very good read may I add for anyone with a technical interest) and have just finished the section on engines (more specifically their locations) and it discusses the advantages and disadvantages of Tail and Wing mounted engines (within and under wing) but does not discuss over wing engines.
I do believe it had been done on one or two planes, however I wanted to spark some intellectual debate on here as to why it is not more common ?

Surely over wing engines
(a) deliver more thrust (airflow) over the wing, thereby increasing lift over the wings as seen by propellers on prop aircrafts ? This in turn surely creates a more economical aircraft as less power is needed to create lift, a sort of tow birds with one stone method ?
This in turn would make the aircraft more responsive to changes in thrust, for example if a sudden burst of power is needed there is less 'lag'.
(b) would it not be better with regards to FOD as they are less prone to sucking in materials
(c) In the event of a crash, is it not 'safer' as engines are less vulnerable, potentially flying in the fuel tanks - an over the wing solution provides that barrier of safety ?
(d) Allow for the possibility of bigger engines which can produce more thrust - the current limitations being ground clearance.

Just a thought...
Wrighbrothers
Always stand up for what is right, even if it means standing alone..
 
xero9
Posts: 124
Joined: Thu Feb 22, 2007 3:12 am

RE: Over Wing Engine?

Wed Aug 11, 2010 4:49 pm

With my basic knowledge of planes, I would assume because the top of the wing is a much more critical part when it comes to generating lift, it makes more sense to keep that surface as smooth as possible.

Also, not sure what kind of effect that would have on say the elevator. I would assume a top mounted engine would blast pretty much directly in to them. I'm not sure if that would affect anything or not, but could be a consideration.

Sorry I didn't really answer your question, but those are just my thoughts!
 
HaveBlue
Posts: 2155
Joined: Fri Jan 30, 2004 3:01 pm

RE: Over Wing Engine?

Wed Aug 11, 2010 5:06 pm

YC-14, An-72 and VFW 614 and Hondajet have over wing engines.

http://img530.imageshack.us/img530/8683/yc141072.jpg
http://img231.imageshack.us/img231/5256/antonovan74.jpg
http://img708.imageshack.us/img708/6214/0901093.jpg
http://img85.imageshack.us/img85/3182/hondajet001.jpg

[Edited 2010-08-11 10:14:34]
 
Fly2HMO
Posts: 7184
Joined: Sat Jan 24, 2004 12:14 pm

RE: Over Wing Engine?

Wed Aug 11, 2010 5:36 pm



Quoting Wrighbrothers (Thread starter):

This in turn would make the aircraft more responsive to changes in thrust, for example if a sudden burst of power is needed there is less 'lag'.

No. Throttle responsiveness has nothing to do with the where the engine is positioned. The only thing you could benefit from in an installation as in the YC-14 and An-72 is a bit of extra lift from the engine "blowing" over the top of the wing. But thrust won't change.

Quoting HaveBlue (Reply 2):
YC-14, An-72

I'm not to sure you can truly consider those over the wing. They blow over the wing, but otherwise the airflow characteristics would be vastly different than the over wing pod as in the Hondajet and the VFW

[Edited 2010-08-11 10:40:41]
 
roseflyer
Posts: 9602
Joined: Fri Feb 13, 2004 9:34 am

RE: Over Wing Engine?

Wed Aug 11, 2010 5:43 pm

Putting the engines above the wing is an inherently unstable thing to do. In basic engineering designs, you usually do not want to put a heavy weight on top of a post. Tension is always prefered to compression as buckling becomes a problem. When you add vibrations to it, it is going to take a lot of reinforcement to keep it stable. On top of the mass of the engine, it is producing thrust which further makes for some large moments.

Engines can be on top, but the structure to support them would be detrimental to airplane weight. Also, engines should be ahead of their mounts so again that they are in tension when the engine is producing thrust. Even on tail mounted airplanes, the support for the engine attaches to the airplane behind the center of mass of the engine.
If you have never designed an airplane part before, let the real designers do the work!
 
XaraB
Posts: 122
Joined: Fri Aug 17, 2007 9:23 pm

RE: Over Wing Engine?

Wed Aug 11, 2010 6:54 pm

Another point I seem to remember from earlier discussions about this:
If engine exhaust is significantly contributing to wing lift, you'd have a serious lift asymmetry in the event of an engine shutdown/failure. Battling such asymmetry at the same time as handling loss of thrust, speed, altitude and/or fire seems a bit unnerving, and is easily avoided by moving the engines somewhere else.
An open mind is not an empty one
 
User avatar
bikerthai
Posts: 3036
Joined: Wed Apr 28, 2010 1:45 pm

RE: Over Wing Engine?

Wed Aug 11, 2010 6:56 pm

Another benefit of under wing engine is:

The moment on an typical commercial wing (airfoil) tends to rotate the wing down.
Countering this moment with an under wing engine pod (thrust) would allow you to reduce the size of the horizontal stabilizer.

bikerthai
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
MHG
Posts: 925
Joined: Mon Dec 13, 2004 1:33 am

RE: Over Wing Engine?

Wed Aug 11, 2010 8:25 pm

Another disadvantage is that you need to feed the engine all the time by a fuelpump.

There´s no such thing like gravity feed availlable in case the pump quits !

Also:
In the engine nacelle you don´t have the space availlable for even a small back up container to feed the engine for a short period (and i can´t imagine designers would like to store any amount of fuel inside the nacelle above the amount the engine needs immediately !!! )
Flying is not inherently dangerous but it is very unforgiving in case of carelessness, incapacity or neglect.
 
roseflyer
Posts: 9602
Joined: Fri Feb 13, 2004 9:34 am

RE: Over Wing Engine?

Wed Aug 11, 2010 8:27 pm

Quoting bikerthai (Reply 6):
The moment on an typical commercial wing (airfoil) tends to rotate the wing down.
Countering this moment with an under wing engine pod (thrust) would allow you to reduce the size of the horizontal stabilizer.

I'll need a free body diagram to understand that.
If you have never designed an airplane part before, let the real designers do the work!
 
etherealsky
Posts: 211
Joined: Fri Apr 09, 2010 6:13 pm

RE: Over Wing Engine?

Wed Aug 11, 2010 9:19 pm

Quoting XaraB (Reply 5):
If engine exhaust is significantly contributing to wing lift, you'd have a serious lift asymmetry in the event of an engine shutdown/failure.

Sort of. While you're right, the thing is, unless it's a purpose-built STOL airplane, most of the lift is still being produced the by the 'relative wind' over the airfoil. There are some exceptions like the Breguet 941, where almost all of the leading edge is in the propwash. (This may be one reason why it used the 4 turboprop engines to drive a common "driveshaft" which in turn drove the propellers. With an arrangement such as this, even a multiple engine failure wouldn't necessarily cause any of the props to stop turning. No doubt an expensive design and a maintenance headache, but probably very reliable.)


View Large View Medium
Click here for bigger photo!

Photo © Steve Williams

Quoting XaraB (Reply 5):
Battling such asymmetry at the same time as handling loss of thrust, speed, altitude and/or fire seems a bit unnerving, and is easily avoided by moving the engines somewhere else.

What do you think it's like to fly single-engine in a Dash 8, ATR, or any light twin for that matter?  
(cue the Cessna 337 jokes  )

With an adequately-sized rudder and decent aerodynamic stability (as most civil aircraft are designed to have) it's not much of a problem once the crew is trained and accustomed to it. Besides, the situation is actually worse in a piston or turboprop compared to a jet because in addition to the rolling moment created by this newfound asymmetrical lift, you also have to deal with the torque of the operating engine, and on many airplanes you also have a 'critical engine' due to P-factor.
"And that's why you always leave a note..."
 
etherealsky
Posts: 211
Joined: Fri Apr 09, 2010 6:13 pm

RE: Over Wing Engine?

Wed Aug 11, 2010 10:25 pm

Quoting bikerthai (Reply 6):

True, assuming that the engine pod is ahead of the CG and the center of pressure is behind the CG.

Quoting RoseFlyer (Reply 8):

Here's a lame drawing I just made to hopefully help sort things out. (Feel free to point and laugh as you see fit  )

As you can see with the engine mounted over the wing, you have the centerline of thrust located above the longitudinal axis of the aircraft. This creates a nose-down pitching moment about the lateral axis, which is at the center of gravity (CG). While the weight of the engine does help counteract it, it must also be countered by an increased amount of downward lift created by the horizontal stab (a greater tail-down moment).



Compare it with a conventional wing-mounted configuration.



You can see how the centerline of thrust is now below the longitudinal axis, and it creates a nose-up pitching moment, which is good because it helps counteract the nose-down pitching moment created by the center of pressure (CP) which is where the sum of all lift created by the wing can be imagined.

Remember, reducing the amount of 'downforce' required from the horizontal stab reduces drag, which means less fuel burn! Additionally, an engine hung under the wing in the conventional position just forward of the leading edge also reduces the structural reinforcement required to counteract wing twist due to lift since it acts like a counterweight (weight savings!)

(Remember, this is just physics coming from a pilot's point of view, and you know what they say about pilots and their comprehension of physics so don't go too hard on me  )

[Edited 2010-08-11 15:29:14]
"And that's why you always leave a note..."
 
Chese
Posts: 29
Joined: Wed Sep 20, 2006 12:17 pm

RE: Over Wing Engine?

Thu Aug 12, 2010 4:23 am

This is no different than present tail mounted engine designs. A boost pump can make up for a failed engine fuel pump.

Quoting MHG (Reply 7):
Another disadvantage is that you need to feed the engine all the time by a fuelpump.

There´s no such thing like gravity feed availlable in case the pump quits !
Note to airliners.net admins, I will not like you on Facebook.
 
User avatar
bikerthai
Posts: 3036
Joined: Wed Apr 28, 2010 1:45 pm

RE: Over Wing Engine?

Thu Aug 12, 2010 4:44 pm

Quoting etherealsky (Reply 10):
etherealsky

Couldn't have done it better mysleft.   
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
mrocktor
Posts: 1391
Joined: Mon Jan 24, 2005 12:57 am

RE: Over Wing Engine?

Fri Aug 13, 2010 8:19 pm

Quoting Wrighbrothers (Thread starter):
(a) deliver more thrust (airflow) over the wing

More thrust, no. More airflow over the wing, yes. The extra lift would only be significant when the plane is flying slowly (this is why you see this sort of configuration on STOL aircraft).

Quoting Wrighbrothers (Thread starter):
(b) would it not be better with regards to FOD as they are less prone to sucking in materials

Yes. This is why it is a favorite configuration for seaplanes.

View Large View Medium
Click here for bigger photo!

Photo © Anton Bannikov

Quoting Wrighbrothers (Thread starter):
(c) In the event of a crash, is it not 'safer'

No. You want the engine protecting the fuel tank, not the fuel tank protecting the engine!  
Quoting Wrighbrothers (Thread starter):
(d) Allow for the possibility of bigger engines which can produce more thrust - the current limitations being ground clearance

Yes, though ground clearance is not usually a huge issue on clean sheet designs (it is a problem for re-engining existing aircraft).

Quoting xero9 (Reply 1):
I would assume because the top of the wing is a much more critical part when it comes to generating lift, it makes more sense to keep that surface as smooth as possible.

  
Any aerodynamic discontinuity on the upper surface of the wing means a (comparatively) huge hit to the lift coeficient you can achieve. Stuff under the wing barely tickles (comparatively). This is why you see military craft loaded with an unbeliavable amount of garbage (aerodynamically speaking) under the wing - and still perfectly capable of flight.
 
A333TS
Posts: 109
Joined: Wed May 28, 2008 3:03 am

RE: Over Wing Engine?

Fri Aug 13, 2010 8:48 pm

Quoting mrocktor (Reply 13):
Yes. This is why it is a favorite configuration for seaplanes.

There may also be issues with water getting inside the engine with engine mounted under the wings on the Beriev BE-200.

Engines mounted over the wing are also protected (somewhat) from derbies.


A333TS
 
etherealsky
Posts: 211
Joined: Fri Apr 09, 2010 6:13 pm

RE: Over Wing Engine?

Sat Aug 14, 2010 12:36 am

Quoting mrocktor (Reply 13):
an unbeliavable amount of garbage



Like this?  
"And that's why you always leave a note..."
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Over Wing Engine?

Sat Aug 14, 2010 1:25 am

 
User avatar
lightsaber
Moderator
Posts: 18651
Joined: Wed Jan 19, 2005 10:55 pm

RE: Over Wing Engine?

Mon Aug 23, 2010 4:26 pm

One issue with engines above the wing is the rotor failure scenario.

As best I can tell, the Hondajet puts the rotating parts aft of the wing.
http://www.theautochannel.com/news/2006/07/25/015916.2-lg.jpg

Heck, we could read the technical paper on the design from Honda (warning, pdf):  http://hondajet.honda.com/pdf/tech_p...o6_P1177_P1184_Wave_Drag_OTWEM.pdf

Notice how under the wing engines are far aft? Their turbine rotor is aft of the wing spar(s) and fuel tanks. Any fuel tanks the rotor might hit have to be armored to take the hit, so it looks like Honda avoided that issue.   

Quoting RoseFlyer (Reply 4):
In basic engineering designs, you usually do not want to put a heavy weight on top of a post.

  

But that isn't as bad is the structure in a tail mounted engine. In a small aircraft, the weight savings with short gear will exceed the structural penalty.


Please read the technical paper for more details. It will help guide this discussion.

Lightsaber
IM messages to mods on warnings and bans will be ignored and nasty ones will result in a ban.
 
OldAeroGuy
Posts: 3887
Joined: Sun Dec 05, 2004 6:50 am

RE: Over Wing Engine?

Mon Aug 23, 2010 6:47 pm

Quoting etherealsky (Reply 10):
As you can see with the engine mounted over the wing, you have the centerline of thrust located above the longitudinal axis of the aircraft. This creates a nose-down pitching moment about the lateral axis, which is at the center of gravity (CG).

You've drawn the thrust vector in the wrong direction, although the words are correct.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
User avatar
Jetlagged
Posts: 2564
Joined: Sun Jan 23, 2005 3:00 pm

RE: Over Wing Engine?

Mon Aug 23, 2010 8:06 pm

I'm not sure the Hondajet counts as an over wing engine design, as the engines are more or less exactly where they would be for a normal business jet except the mounting structure attaches to the wing, not the rear fuselage.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
 
redflyer
Posts: 3905
Joined: Thu Feb 24, 2005 3:30 am

RE: Over Wing Engine?

Mon Aug 23, 2010 11:28 pm

There is also the issue of ground personnel having easy access to servicing an over-the-wing mounted engine. I would think having "wing walkers" and their associated tools and parts moving onto and off of the top portion of the wing during servicing would result in damage to that critical part, requiring another reason to beef up and add even more weight to the structure around the engine.
A government big enough to take away a constitutionally guaranteed right is a government big enough to take away any guaranteed right. A government big enough to give you everything you need is a government big enough to take away everything you have.
 
mrocktor
Posts: 1391
Joined: Mon Jan 24, 2005 12:57 am

RE: Over Wing Engine?

Tue Aug 24, 2010 12:15 pm

Quoting lightsaber (Reply 17):
As best I can tell, the Hondajet puts the rotating parts aft of the wing.

Nevertheless at least the opposite wing (and likely some part of the on side wing) is exposed to uncontained fan debris.

Quoting lightsaber (Reply 17):
Any fuel tanks the rotor might hit have to be armored to take the hit

Actually they don't. You do have to be able to cope with the fuel asymmetry due to the leak (roll authority) and to guarantee fuel reserves for the diversion (remember an engine can hit the opposite wing, so some sort of cross feed capability is required). But no armor necessary.

Quoting jetlagged (Reply 19):
I'm not sure the Hondajet counts as an over wing engine design, as the engines are more or less exactly where they would be for a normal business jet except the mounting structure attaches to the wing, not the rear fuselage.

Well the engine is mounted on a pylon over the wing, so thats that. But you are right, the engine position is pretty much exactly where you'd expect (maybe a wee bit more outboard - which you don't do on fuse mounted engines because of the structural penalty of a long pylon, and end up having to "coke bottle" your fuselage to deal with wave drag - see Citation X for an exagerated example).
 
User avatar
lightsaber
Moderator
Posts: 18651
Joined: Wed Jan 19, 2005 10:55 pm

RE: Over Wing Engine?

Wed Aug 25, 2010 3:04 pm

Quoting mrocktor (Reply 21):
Nevertheless at least the opposite wing (and likely some part of the on side wing) is exposed to uncontained fan debris.

The blade out test requires no parts exit the engine radially. The fan can be contained. If a turbine fails, the rotor chunks go where they will.  

The HF-120 is scheduled for a blade out test (might even have occurred by now) :

http://www.ainonline.com/news/single...ontinues-for-hf120-turbofan-23621/

So the fan will be a non-issue on the Hondajet.

Quoting mrocktor (Reply 21):
But no armor necessary.

Fair enough, it must be an internal requirement... Or perhaps that was the only way to ensure a *long* diversion requirement? Anyway, I'm butting up onto an NDA and I'm not a fuel tank designer. We just had them very unhappy with engine placement.  
Quoting redflyer (Reply 20):
I would think having "wing walkers" and their associated tools and parts moving onto and off of the top portion of the wing during servicing would result in damage to that critical part, requiring another reason to beef up and add even more weight to the structure around the engine.

You are correct. But due to the 'recovered volume' by not mounting the engines aft on the tail of the aircraft, the Hondajet solution should be lighter than if Honda had designed the airframe with tail mounted engines.

It will be interesting to see how the Hondajet does versus the Phenom 300 (in my opinion, the closest rival). But due to the gap in EIS, it won't be a pure 'airframe versus airframe' competition.

Lightsaber
IM messages to mods on warnings and bans will be ignored and nasty ones will result in a ban.
 
mrocktor
Posts: 1391
Joined: Mon Jan 24, 2005 12:57 am

RE: Over Wing Engine?

Thu Aug 26, 2010 7:27 pm

Quoting lightsaber (Reply 22):
The fan can be contained.

No, it cannot. In fact, of all the rotors the fan has by far the highest energy. What can be contained (and is tested for Part 33 certification) is a fragment consisting of at least 80% of the length of one blade (typically the test is executed breaking at something between 85% and 90% to make sure you get a valid test point).

The rotor burst model for aircraft certification contains a fragment that is one third of the whole disk. This fragment's energy is probably of the order of 30,000 to 40,000 ft.lbf on that plane (a rifle shot has about 8,000 ft.lbf energy). There is no way that thing is contained.



[Edited 2010-08-26 12:32:04]
 
User avatar
lightsaber
Moderator
Posts: 18651
Joined: Wed Jan 19, 2005 10:55 pm

RE: Over Wing Engine?

Sat Aug 28, 2010 4:39 am

Quoting mrocktor (Reply 23):
No, it cannot. In fact, of all the rotors the fan has by far the highest energy. What can be contained (and is tested for Part 33 certification) is a fragment consisting of at least 80% of the length of one blade (typically the test is executed breaking at something between 85% and 90% to make sure you get a valid test point).

True. But it is unlikely to have a fan rotor fail. I said the fan would be contained (and chose poor words, I admit). I should have said a 'reasonable fan failure will be contained.'

Quoting mrocktor (Reply 23):
The rotor burst model for aircraft certification contains a fragment that is one third of the whole disk. This fragment's energy is probably of the order of 30,000 to 40,000 ft.lbf on that plane (a rifle shot has about 8,000 ft.lbf energy). There is no way that thing is contained.

I should have said fan blade. I am unaware of a fan rotor failure. Have their been any? The belief is there won't be. I know of two turbine rotor failures (there have probably been more).

It is believed that the rotors will fail in three pieces. But the rotor with the highest 'risk' is the turbine.

I apologize for the wrong wording. As far as risk is concerned, the fan rotor is less worrisome to me than the turbine rotor due to the relative stresses and heat.

Lightsaber
IM messages to mods on warnings and bans will be ignored and nasty ones will result in a ban.
 
mrocktor
Posts: 1391
Joined: Mon Jan 24, 2005 12:57 am

RE: Over Wing Engine?

Mon Aug 30, 2010 12:03 pm

Quoting lightsaber (Reply 24):
But it is unlikely to have a fan rotor fail. I said the fan would be contained

Very true, there have been no disk failures of 3rd generation turbofans ever (this means turbofans designed after the 80's), but the cert requirement doesn't care about that - you must assume the failure.

Quoting lightsaber (Reply 24):
I am unaware of a fan rotor failure. Have their been any?

Plenty, but not on modern engines. Here is an ugly one (see pg. 13)

Quoting lightsaber (Reply 24):
I apologize for the wrong wording. As far as risk is concerned, the fan rotor is less worrisome to me than the turbine rotor due to the relative stresses and heat.

The statistics agree with you. The bureaucracy does its own thing, of course.
 
User avatar
lightsaber
Moderator
Posts: 18651
Joined: Wed Jan 19, 2005 10:55 pm

RE: Over Wing Engine?

Mon Aug 30, 2010 4:12 pm

Quoting mrocktor (Reply 25):
The statistics agree with you. The bureaucracy does its own thing, of course.

Touche' and thank you for the information and link.

The bureaucracy exists to feed itself after the first generation have retired...

Lightsaber
IM messages to mods on warnings and bans will be ignored and nasty ones will result in a ban.
 
User avatar
kanban
Posts: 3991
Joined: Sun Jan 06, 2008 1:00 am

RE: Over Wing Engine?

Mon Aug 30, 2010 5:53 pm

so what are the thoughts on the blended wing with 3 above the wing/fuselage aft mounted engines?
 
mrocktor
Posts: 1391
Joined: Mon Jan 24, 2005 12:57 am

RE: Over Wing Engine?

Mon Aug 30, 2010 6:59 pm

Quoting kanban (Reply 27):
so what are the thoughts on the blended wing with 3 above the wing/fuselage aft mounted engines?

It has a lot going for it (of course for aircraft a lot bigger than the Honda Jet).

These are not exhaustive, evidently:

Pluses:
+ Noise footprint is significantly reduced with the fuselage shielding the engines and exhaust from the ground and the vertical surfaces shielding them laterally (in most configurations)
+ Boundary layer ingestion: most engines ingest free flow air, so you are decelerating all that air mass as it goes into the inlet and re-accelerating it (more) to produce thrust - by ingesting the air near the fuselage trailing edge those engines are ingesting air that is already slowed down (by skin drag) for a net decrease in total drag

Minuses
- Engine access for maintenance (must climb onto the aircraft, no access from ground)
- Boundary layer ingestion: ingesting disturbed airflow requires the engine to be designed for this (fan blade geometry, loading, I have no idea how many other factors are affected)

From an uncontained rotor failure perspective (which is what we were last discussing) the configuration poses some challenges in systems routing, but nothing impeditive (especially with the engines staggered and not lined up).

Lots of information about this configuration here.
 
User avatar
Devilfish
Posts: 6681
Joined: Tue Jan 24, 2006 7:52 am

RE: Over Wing Engine?

Tue Aug 31, 2010 11:41 pm

Where does "Mickey Mouse" fit in all of the above?.....

View Large View Medium
Click here for bigger photo!

Photo © Egor Naumenko
View Large View Medium
Click here for bigger photo!

Photo © Dmitry Karpezo

"Everyone is entitled to my opinion." - Garfield
 
Fly2HMO
Posts: 7184
Joined: Sat Jan 24, 2004 12:14 pm

RE: Over Wing Engine?

Wed Sep 01, 2010 3:10 am

Quoting DEVILFISH (Reply 29):
Where does "Mickey Mouse" fit in all of the above?.....

N/A. The engines are basically ahead of the wing, but in this particular configuration it's a blown wing, the engine's thrust flowing over the wing creates additional lift.
 
User avatar
lightsaber
Moderator
Posts: 18651
Joined: Wed Jan 19, 2005 10:55 pm

RE: Over Wing Engine?

Sat Sep 04, 2010 7:24 pm

Quoting mrocktor (Reply 28):
Lots of information about this configuration here.

My adobe reader is reporting a 'damaged file' and is unable to open the pdf. Do you have another link?

Lightsaber
IM messages to mods on warnings and bans will be ignored and nasty ones will result in a ban.
 
User avatar
kanban
Posts: 3991
Joined: Sun Jan 06, 2008 1:00 am

RE: Over Wing Engine?

Sat Sep 04, 2010 10:52 pm

Quoting lightsaber (Reply 31):
My adobe reader is reporting a 'damaged file' and is unable to open the pdf. Do you have another link?

try this...

http://aviationweek.typepad.com/files/mit_n3_final_presentation.pdf
 
mrocktor
Posts: 1391
Joined: Mon Jan 24, 2005 12:57 am

RE: Over Wing Engine?

Thu Sep 09, 2010 4:17 pm

Quoting lightsaber (Reply 31):
My adobe reader is reporting a 'damaged file' and is unable to open the pdf. Do you have another link?

Sorry, don't have an alternate source (kanban's link is identical to mine). I just re-downloaded the file and it worked fine. If you are trying to open the link directly, right click and save to your HD instead (there are a lot more problems with Adobe-browser compatibility than with Adobe itself). Also, it is a good 8Mb so if you are on a jittery connection that could be an issue.
 
User avatar
lightsaber
Moderator
Posts: 18651
Joined: Wed Jan 19, 2005 10:55 pm

RE: Over Wing Engine?

Fri Sep 10, 2010 5:43 am

Quoting mrocktor (Reply 33):
I just re-downloaded the file and it worked fine.

It worked for me this time, my connection must have been bad last night... or I didn't wait long enough. (See signature... Daddy is tired. Mommy more so.)  

Interesting... but it is at a slower cruise speed. I like the 5,000 ft 'balanced field' performance for the domestic version. I'm all in favor of 'lifting noses' and 'lifting bodies.' (They just seem like 'natural technologies.')

I'm not into T-tails. There great for theoretical aerodynamics, but in the real world, they have some deficiencies. (There is a reason most academic aircraft have them and so few field aircraft do.)

Lightsaber
IM messages to mods on warnings and bans will be ignored and nasty ones will result in a ban.

Who is online

Users browsing this forum: Sokes, workhorse and 43 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos