The Aviation Thread [Contains Lots of Awesome Pictures]

[Blind_Io]

WillDAQ,

It's a concept design, not production, so patents don't matter.
The engine access could be done easily if the wing was made to hold the mechanic, it would be easily accessed for maintenance.
The Honda Jet's wing is close to the ground, it doesn't mean the delta has to be that low, actually, that's an interesting idea. What about a high delta wing with a low-slung engine and a low and forward canard? You think the canard that far forward would screw up the lift at certain angles of attack?

I still like the idea of the delta and canard to make a nice roomy cabin and a large baggage hold without having to drop the wing low like in the Honda or some of the Leers.

As for awesome aircraft:

http://pic.armedcats.net/b/bl/blind_io/2009/08/14/DeltaAirlinesDc3_1.jpg

I have actually been aboard this plane (not in flight, unfortunately). This is actually Delta's first aircraft. It was taken over by the government for WWII then returned to Delta where it went back into service. It was finally sold and forgotten. Years later Delta decided to find the plane, expecting it to be in a boneyard, they tracked it down in South America where it was still flying cargo. It had over 1 million flight hours on the airframe. Delta flew it back to the US (with every warning light on, according to the pilot I spoke to) and it was fully restored, complete with custom dyed and woven carpet and seat covers to make it original. The attention to detail is amazing, they spent over a year looking for the phone cord for the aft galley phone.

Here are a couple photos I took when I saw this aircraft. Sorry if they look crooked, it's from the scanning:

http://pic.armedcats.net/b/bl/blind_io/2009/08/14/911852619_l.jpg

http://pic.armedcats.net/b/bl/blind_io/2009/08/14/911852859_l.jpg

http://pic.armedcats.net/b/bl/blind_io/2009/08/14/911852955_l.jpg

 

[WillDAQ]

WillDAQ,

It's a concept design, not production, so patents don't matter.

Generally speaking "it's a really good concept... although you can't actually produce it for legal reasons" is going to be an interesting argument to put forward. I watched (with some amusement) a team at our Uni get mauled by a guy from Airbus for that very reason.

The engine access could be done easily if the wing was made to hold the mechanic, it would be easily accessed for maintenance.

The issue is engine removal, the process of replacing engines requires a far more complicated rig to be completed safely compared to just dropping them down.

Some people might be interested in this, a 747(IIRC) in for heavy maintenance, note how the hanger is designed to fit the aircraft.

The Honda Jet's wing is close to the ground, it doesn't mean the delta has to be that low, actually, that's an interesting idea. What about a high delta wing with a low-slung engine and a low and forward canard? You think the canard that far forward would screw up the lift at certain angles of attack?

Three main problems
- under slung engines on a delta lack the same aerodynamic benefits of under slung on a normal wing
- canards susceptible to damage on the ground
- canard tip vorticies over the wing

Other than that it might work

 

[Blind_Io]

Now that is an awesome hangar!

Would winglets on the canards reduce the wingtip vortex?

I'm loving this conversation, I've never had a chance to learn so much about aviation design and fluid dynamics before!

 

[Labcoatguy]

- under slung engines on a delta lack the same aerodynamic benefits of under slung on a normal wing

Does that explain why the only major plane to have had them is the B-58? Can't think of any others; don't think the Concorde's count, as the pods hug the wing.

 

[WillDAQ]

Now that is an awesome hangar!

I'll fish out some more maintenance porn and post it up here.

Would winglets on the canards reduce the wingtip vortex?

A little known fact is that if you have a winglet Xft tall, it is less beneficial than simply increasing the span by Xft instead. Winglets started off as a method of increasing performance without exceeding the 80m limit of a typical aircraft stand, but are now fitted to smaller aircraft as much a fashion accessory as an aerodynamic device.

Does that explain why the only major plane to have had them is the B-58? Can't think of any others; don't think the Concorde's count, as the pods hug the wing.

Sort of, there are two distinct functions that the pylons fulfill. For transonic and supersonic flight they can be shaped acording to area ruling to reduce pressure gradients and hence delay shock formations. For low speed flight they can act as wing fences, reducing spanwise flow which improves stall characteristics.

 

[WillDAQ]

I know we're still a little off topic, but i'm guessing this thread is being read by aircraft buffs... these are some random pics of stuff you'd not normally see.

First the engine porn:

Some of you may know that most of the air passed through a turbo fan doesn't actually go through the jet within, you can in the first pic that after the first fan the flow is split between bypass and core. The second pic shows the bypass duct opened to reveal the core engine. Pic three shows the core flow being mixed back into the bypass flow. The funky titanium nozzle is used to mix the two streams as efficiently as possible to reduce engine noise.


And now for some "omg planes are flimsy" pics! (Both of these parts are critical, they fail and the plane will crash!)

Spoiler

These are the control wires that connect the pilots controls in the cockpit back to the hydraulic servo control units in the tail. This is what's above your overhead lockers!

This hydraulic jack lives in the tail (the thing on the left is the rear pressure bulkhead that represents the end of the cabin) and is used for varying the incidence of the tail. The entire tailplane can pivot ~ 10 degrees each way and this jack is the only thing holding it at the correct angle.

Right, I think that's enough geek pics for one lifetime.

 

[Blind_Io]

Some Cold-War porn: The B-58 Hustler, one of my all time favorite bombers.

http://pic.armedcats.net/b/bl/blind_io/2009/08/14/b58ab.jpg

http://pic.armedcats.net/b/bl/blind_io/2009/08/14/b58_04.jpg

http://pic.armedcats.net/b/bl/blind_io/2009/08/14/B-58_Hustler.jpg

 

[nsx_23]

WillDAQ, from a maintenance point of view, any good general design pointers?

 

[ChrisSRT4]

Damn I really have to upload my pictures from EAA a few weeks ago. Many many pics were taken! ( c:

 

[WillDAQ]

WillDAQ, from a maintenance point of view, any good general design pointers?

Err.. nothing sweeping and general. The engines are a problem as they are swapped on and off, most other stuff just needs access hatches and the like.

 

[nsx_23]

I'm just worried about making sure there's enough gound clearance for the engines for rough-airfield operation.

 

[w1lhelm]

WillDAQ, you mentioned canard tip vortices on the wing.

Couldn't it be made into a benefit for higher AoA operation? (Abseloutely perfect for a regional jet)
I just really want a canard.

Edit: Some awesomeness must be included.
[YOUTUBE]http://www.youtube.com/watch?v=EQw5AjrBjXE[/YOUTUBE]

 

[nsx_23]

But I don't think you'd need that much AoA on a regional jet though. Passengers would feel quiet uncomfortable with a high AoA.

Also, wouldn't front canards require some pretty expensive control hardware?

 

[w1lhelm]

Well since all of the crazy/strange ideas have been discarded so far, could you explain the benefit of this?

 

[WillDAQ]

WillDAQ, you mentioned canard tip vortices on the wing.

Couldn't it be made into a benefit for higher AoA operation? (Abseloutely perfect for a regional jet)
I just really want a canard.

Generally speaking, no.

Some aircraft do have vortex generators located on the nose which are designed to alter the flow at the tail, however to achieve that you need a generator that has been specifically designed for the job. They also tend to be bodge fixes for things that were wrong to start with.

If you're looking to create an effective efficient canard you're left with little "wiggle room" left in the design to dictate the vortex behaviour. As the AoA and loading of the canard changes the vortex strength and location will move about, making it pretty useless for controlling downstream flow.

You don't really want high AoA in any passenger aircraft, floor angles of more than say 10 degrees in pitch don't go down well with pax. Most airliners have high aspect ratio wings with high lift devices, which increase the lift curve slope (rate of increase of lift with AoA). Hence when slowing down they don't need to fly at high AoA to keep the required lift, giving shallow floor angles and happy pax.

 

[WillDAQ]

Well since all of the crazy/strange ideas have been discarded so far, could you explain the benefit of this?

Urgh.. now we're into the realm of crazy! There are some rather wide ranging reasons you might go down this road including:

- Re-use of parts from smaller aircraft to allow fast development
- Option for two distinct cockpits, providing damage tolerance
- Ability to fit very wide undercarriage for stability
- High lift center wing with stall resistant outer panels
- Higher fuselage volume (at the cost of high skin area!)
- Strength

However, the reasons not to are numerous and obvious!

If it were me i'd probably be looking at a conventional design with some form of mildly non planar wing, lots of composites and low maintenance costs.

Also, vorticies!

 

[nsx_23]

WillDAQ, do you work around aircrafts by any chance??

Whats it like in industry? I'm a bit worried about job prospects tbh.

 

[WillDAQ]

WillDAQ, do you work around aircrafts by any chance??

Whats it like in industry? I'm a bit worried about job prospects tbh.

Well, i've just finished a degree in aeronautical engineering, i've got a pilots licence and i've worked a little in industry... so I can't be that far ahead of you.

I actually turned down two jobs to start a PhD, but I have no idea what the industry is like in Melbourne!

 

[nsx_23]

Ah, I'm still in 3rd year of an aerospace eng degree, so you are certainly more ahead of me....

Damn the coursework is hard though.

 

[w1lhelm]

For someone that is considering a degree in Aerospace Engineering and job in the field, would both of you reccomend/advice against it?

Read a bit about the twin planes, seemed like temporary solutions until a better improvment came along