So can anyone explain what;s the point of Mk3 plane parts.

[Mahnarch]

Some of these look awesome.

I'm going to have to try out some designs with these parts.

[Sidereus]

http://i.imgur.com/4un1U9A.png

It's big.

It's roomy (space for 16 Kerbals)

It's powerful (12 km\s dV with full tanks)

I love this ship

What engines are you using with that sucker? They don't look stock.

12 km/s dV would make it a great Eve lander, if the engines provide enough TWR...

[UnusualAttitude]

Although they are a challenge to design, Mk3 spaceplanes are not only feasible; they are extremely useful. They now provide almost all of my heavy lifting and supply requirements in career, for just the cost of fuel. Station modules, exploration vehicles, full orange cans of fuel, you name it...

Or recreational activities, such as speed runs on the Flats of Minmus...

[AbacusWizard]

The only problem I have with the Mk3 cargo bay is that it can't be used to lift things bigger than the Mk3 cargo bay up to orbit.

[Armchair Rocket Scientist]

It's nice they're making bigger wings and landing gear for 1.0, but I also think they need to make bigger intakes and air-breathing engines too. Seriously, I don't want to have to strap on 12 Turbojets (which are arguably overpowered to begin with) just to get a Mk3 aircraft off the ground.

+1 on larger jet engines. In particular a giant 2.5m turbofan would be approximately to scale with the GE90, which is used on real aircraft.

In addition, hopefully the less soupy aerodynamics in 1.0 will allow planes to get off the ground with lower TWRs: modern jetliners typically only have a TWR of 0.3.

[Valley]

I don't make space planes, made one working shuttle once for a challenge, rarely fly planes, and find the new parts don't really fit the style of my craft or stations. It is easier for me - at my skill level - to delivery cargo and parts on the nose of a basic rocket then make a re-usable shuttle or space plane.

Now, I have yet to make a interplanetary mother ship and can see where these parts could be useful in making one - but I plan to wait till 1.0 before trying that because at that point I could refuel it (easier). In other words - as of now - the Mk 3 parts (and most of the plane parts outside of some jet engines or parts for making SSTO craft) are not very useful (to me).

[Yakuzi]

The only problem I have with the Mk3 cargo bay is that it can't be used to lift things bigger than the Mk3 cargo bay up to orbit.

Yes..... If only there was a cargo bay that could hold MK3 parts... and corresponding parts of course

Or fairings, or orbital construction (I wish that Squad would include some sort of space welding tool).

[AbacusWizard]

I do often use spaceplanes for moving crew around (and sometimes for getting very small payloads to orbit), but those are almost all Mk1 or (rarely) Mk2.