av-r8 winglet or deltadelux winglet - is there a reason to pick on over the other in certain situations or is one always better?

[paul23]

Well those two winglets seem to fit the same purpose, both adding control at the bottom of a rocket-stack.

 

However the av-r8 winglet seems clearly superior: much larger control surface (full winglet instead of a tiny fraction). Only weighing a fraction more (and often in the first-to-throw) stage so it won't matter.

 

Is there any reason I would pick delta-deluxe winglet over the av-r8? Other than looks which cannot be discussed.

[swjr-swis]

24 minutes ago, paul23 said:

Is there any reason I would pick delta-deluxe winglet over the av-r8?

I like the looks and form of the AV-R8, but there's plenty of practical reasons to pick the delta:

• Cost. 40 funds cheaper. Depending on the requirements or the available budget that might just make the difference.
• Lift. 0.15 wing area more to get higher (or lift more overall weight).
• Weight. 0.022 t less per winglet to push.
• Form. The shape of the wing may be just the fitting piece of the puzzle for your airframe.
• If you need something that adds a good amount of stabilization and just a bit of control, the delta wins.
• If you need something that gives you both a fixed wing with better lift, and a control surface, the delta wins.

 

45 minutes ago, paul23 said:

Other than looks which cannot be discussed.

The main reason it's often scoffed upon is its not-so-sleek looks. So when you explicitly single that out, the delta pretty much wins on all counts except as a pure control surface.

[paul23]

1 minute ago, swjr-swis said:

I like the looks and form of the AV-R8, but there's plenty of practical reasons to pick the delta:

• Cost. 40 funds cheaper. Depending on the requirements or the available budget that might just make the difference.
• Lift. 0.15 wing area more to get higher (or lift more overall weight).
• Weight. 0.022 t less per winglet to push.
• Form. The shape of the wing may be just the fitting piece of the puzzle for your airframe.
• If you need something that adds a good amount of stabilization and just a bit of control, the delta wins.
• If you need something that gives you both a fixed wing with better lift, and a control surface, the delta wins.

 

The main reason it's often scoffed upon is its not-so-sleek looks. So when you explicitly single that out, the delta pretty much wins on all counts except as a pure control surface.

How are the delta wing better, when they have so little actual control surface area?

[swjr-swis]

5 minutes ago, paul23 said:

How are the delta wing better, when they have so little actual control surface area?

Uhm...

12 minutes ago, swjr-swis said:

I like the looks and form of the AV-R8, but there's plenty of practical reasons to pick the delta:

• Cost. 40 funds cheaper. Depending on the requirements or the available budget that might just make the difference.
• Lift. 0.15 wing area more to get higher (or lift more overall weight).
• Weight. 0.022 t less per winglet to push.
• Form. The shape of the wing may be just the fitting piece of the puzzle for your airframe.
• If you need something that adds a good amount of stabilization and just a bit of control, the delta wins.
• If you need something that gives you both a fixed wing with better lift, and a control surface, the delta wins.

(...)

The main reason it's often scoffed upon is its not-so-sleek looks. So when you explicitly single that out, the delta pretty much wins on all counts except as a pure control surface.

[Spricigo]

You already said it: The delta deluxe is lighter.

Also cheaper with a larger relative wing area.

You just didn't realized those are often bigger advantages than larger control surface area. In other words that " adding control at the bottom of a rocket-stack" is far from the only purpose that the delta-deluxe can fit. Examples given: https://kerbalx.com/parts/143

 

 

[AHHans]

25 minutes ago, paul23 said:

How are the delta wing better, when they have so little actual control surface area?

Depends on what you want: do you need mostly control surface? Then the AV-R8 is better.

Do you mostly need an aero-surface with just a bit of control? Then the Delta-Deluxe is better.

All in all I think that you could get nearly all of the craft to work with either of them.

[bewing]

As I recall, the last time I did the full comparison the Tailfin is superior to everything else. You don't need a lifting surface at the back end. You need control surface area.

[Hotel26]

52 minutes ago, bewing said:

You don't need a lifting surface at the back end. You need control surface area

Respectfully, I wonder about this.  For purely simple weather-vaning a potentially stronger counter-lift could easily be superior to a weaker but controllable force.  This would depend upon whether the craft has a simple profile staying in or very close to Sfc Prograde during the lower atmospheric phase.  This is often the case, excepting the relatively low-speed pitch-over maneuver.  A higher total surface area might be quite superior to a lower control surface area, even if that's the whole part.

Of course, there are some craft (e.g. boosting a winged payload) with an unavoidably near-neutral stability, that are not so simple and benefit from or require proactive control.  With those, I anyway tend toward speed-limiting until reaching higher altitudes, since this (it seems to me) is the most reliable strategy.  (Either that, or sometimes electing to use disposable shuttle fins.)

As always: experimentation...  lots of it.

Edited November 15, 2020 by Hotel26

[Spricigo]

1 hour ago, bewing said:

You need control surface area.

Not while I have the rotation gizmo. 

[paul23]

On 11/15/2020 at 12:23 AM, bewing said:

As I recall, the last time I did the full comparison the Tailfin is superior to everything else. You don't need a lifting surface at the back end. You need control surface area.

Having a lifting surface means that the center of lift moves further back due to an object. The more lift a tailfin generates the further it moves back. One would always want the center of lift behind the center of mass.