How to reduce drag with structural components(and wings)?

[Reusables]

Hello!

I was designing a new prop. plane, which included a structural component(small cubic one) to hold a engine.

So it files, but there seems to be one problem: speed.

(It can't beat 50~60m/s )

I know that proplanes can't have very fast speed. The problem is, there is similar proplane I made which is much more faster. this one seems to be slower even with bigger thrust.

The only differences I saw was:

1. The slower one used structural component to hold engines.

2. The slower one has bigger wings for prop. engine, which might have bigger drag.

3. The slower one has shorter cone, which would be more draggy.

 

So how can I reduce drag in this situation? Are there some great techniques to reduce drag? If there is, please let me know and it'll be greatly appreciated!

+ Also I'd like to know which structural part with node attachment? This is necessary to offset parts far enough.

[GoSlash27]

Abastro,

 I have absolutely no experience with prop planes in KSP, so my advice might be totally wrong. Take that for what it's worth...

In my experience, most of the drag in KSP aircraft comes from the fuselage being misaligned with airflow and control surface deflection. To combat this, you want the main wing to have enough incidence (leading edge above trailing edge) to keep the nose aligned prograde in level flight and tailplane rotated so that it requires no trim at cruise speed.

HTHs,
-Slashy

 

[Guest]

Short cone is actually less draggy at subsonic speeds - https://www.youtube.com/watch?v=o9BL4dqMyTE

I remember getting a huge speed boost in a prop plane by sweeping the wings. Even a slight angle makes a big difference over a flat leading edge.

Edited December 17, 2016 by Guest

[Foxster]

Eliminate stuck-on parts like RCS ports, and unnecessary flaps, tanks, wing sections,  engines, intakes, basically anything the craft doesn't really need. 

Don't use anything bigger than mk1 parts. The drag goes up a lot. 

Have your AoA tending towards zero during flight. 

Use streamlined parts to attach bolt-ons. Small hardpoints are lower drag than most other parts you could use for this. 

Streamline the back of stacks as well as the front. 

[Reusables]

8 hours ago, GoSlash27 said:

Abastro,

 I have absolutely no experience with prop planes in KSP, so my advice might be totally wrong. Take that for what it's worth...

In my experience, most of the drag in KSP aircraft comes from the fuselage being misaligned with airflow and control surface deflection. To combat this, you want the main wing to have enough incidence (leading edge above trailing edge) to keep the nose aligned prograde in level flight and tailplane rotated so that it requires no trim at cruise speed.

HTHs,
-Slashy

 

Thanks for the great tip, I really didn't know that the hull had that much drag. (I thought it had some kind of lift, but it certainly isn't )

8 hours ago, String Witch said:

Short cone is actually less draggy at subsonic speeds - https://www.youtube.com/watch?v=o9BL4dqMyTE

I remember getting a huge speed boost in a prop plane by sweeping the wings. Even a slight angle makes a big difference over a flat leading edge.

I didn't expect the shorter cone to be better.

About sweeping the engine.. I already tried that, but it wasn't effective enough.

3 hours ago, Foxster said:

Eliminate stuck-on parts like RCS ports, and unnecessary flaps, tanks, wing sections,  engines, intakes, basically anything the craft doesn't really need. 

Don't use anything bigger than mk1 parts. The drag goes up a lot. 

Have your AoA tending towards zero during flight. 

Use streamlined parts to attach bolt-ons. Small hardpoints are lower drag than most other parts you could use for this. 

Streamline the back of stacks as well as the front. 

Thanks for providing basic rules for reducing drag! I might have overlooked some of them.. Especially with wings.

(Although, I want to make mk3 parts to fly, for something like economy-class passenger plane, and eve rocket transporter)

 

I think I should post some photos of my craft, so that further investigation would be possible.

Some more potential problems I could find was:

1. If the rotor is not occluded with the stator cylinder, then it'll be definitely producing much drag. I might have to try to reduce drag of those parts.

2. Part of the rotor is located in the fairings, but there is certain possibility that it does not protect the separated rotor parts.

      In this case, the rotor should be redesigned thoroughly, I think. I might have to make one out of aerodynamic cones.

3. The most of the wing parts including swept wing to hold wheels and sloped wings would not be needed.

 

I'll try to experiment on 1 and 2. If there is some more problems I couldn't catch, please let me know!

[Foxster]

Umm, I'm far from an expert but it looks to me like it is basically high drag and low power. Can't have both if you want to go quick. .

Assuming you want to stick with the props then something will have to give on the fat fuselage and/or wing sections.  

[Reusables]

6 minutes ago, Foxster said:

Umm, I'm far from an expert but it looks to me like it is basically high drag and low power. Can't have both if you want to go quick. .

Assuming you want to stick with the props then something will have to give on the fat fuselage and/or wing sections.  

Hmm, so the wings and engines are both the problem..

Anyway, I did some experiment on decoupled part in the fairing.

http://imgur.com/a/adkuh

So the fairing seems to work fine even with decoupled parts. Now I should experiment on decoupled parts with same form factors...

[GoSlash27]

Wow, that's funky! I like it.

You can see that your nose is sitting on top of the prograde vector. That means you've got 5° pitch relative to the wind and you're generating drag. If you rotate the wings about 3° that should go away and allow you to fly faster.

Best,
-Slashy

[Reusables]

Maybe this is something straightforward, but it was found out that same form factors doesn't matter with drags.

http://imgur.com/a/IGdX4

Though this might not be accurate experiment, this means that I should redesign my engine...

[GoSlash27]

Yes, decoupled parts are draggier than coupled parts. This is because once they are decoupled there is no longer any occlusion going on. We took advantage of this early in 1.0 to ride our decoupled heat shields to a safe parachute deployment speed.

Best,
-Slashy

[Reusables]

35 minutes ago, GoSlash27 said:

Wow, that's funky! I like it.

You can see that your nose is sitting on top of the prograde vector. That means you've got 5° pitch relative to the wind and you're generating drag. If you rotate the wings about 3° that should go away and allow you to fly faster.

Best,
-Slashy

I'd fix it, it does seem to be one of the problem. Thanks for pointing that!

7 minutes ago, GoSlash27 said:

Yes, decoupled parts are draggier than coupled parts. This is because once they are decoupled there is no longer any occlusion going on. We took advantage of this early in 1.0 to ride our decoupled heat shields to a safe parachute deployment speed.

Best,
-Slashy

I didn't know that it works that way. So it was one of the 'bugs' which is fixed on 1.0? That's interesting.

[GoSlash27]

2 hours ago, Abastro said:

I didn't know that it works that way. So it was one of the 'bugs' which is fixed on 1.0? That's interesting.

Well.. the bug was that the ablator wasn't draggy enough to slow the capsule to a safe deployment speed before smacking into the ground. The workaround was to exploit this bug instead

Best,
-Slashy