Wings with end plates

[Ricardo Moura]

Happy 2022 and greetings from Cleveland.

On Nov 14th of last year, the Kitplanes published an online article about end plates and winglets (link: https://www.kitplanes.com/design-process-end-plates-and-winglets/).

I am curious if anyone here has ever seen or considered installing an end plate on a Sonerai.

Any thoughts?

Cheers!

 

[Schmleff]

Nearly anything is better than the stock rounded tip.

 

[soneraifred]

I don’t know of anyone installing end plates, but if you look at the photos of the prototype Sonerai I on the Sonex Aircraft website, you’ll see that there were no wing tips, just a full end rib with no lightening holes.

 

[Ricardo Moura]

I don’t know of anyone installing end plates, but if you look at the photos of the prototype Sonerai I on the Sonex Aircraft website, you’ll see that there were no wing tips, just a full end rib with no lightening holes.

True. Interesting observation.

Thank you both for your input.

 

[tls258]

Interesting subject. Lots of strategies and theories dating to the beginning of aviation time. https://en.wikipedia.org/wiki/Wingtip_device

End plate or Hoerner seem easiest but can change wing loading and are relatively inefficient. Article references some glider wing designs using winglets, so there are some efficiencies for light aircraft. Rutan incorporated them in several designs. Bellanca used for earlier horizontal stabilizer design altough he was more concerned with the prop wake.

If one looks at page 1-3 of Hoerner’s book “Fluid-Dynamic Drag” (Available on Scribd), he makes the useful observation that the particles rotating in the vortex, called “circulation”, can be visualized as cars on a rotating Ferris wheel. The wingtip vortices interfere with the laminar on the outboard wing. The goal of winglets is to take this rotation that is perpendicular to the direction of the wing movement through undisturbed air and redirect it so that the rotational energy moves longitudinal and contributes thrust to the wing like tires on a car rotating in the direction you want to go. The winglets employ an airfoil to achieve this. Kinda like flying a little wing into the vortex created by the larger wing. Intuition would say that the winglets would have an inverted airfoil shape to introduce the high pressure into a shape that is creating low pressure at the same place.

An endplate acts as a simple barrier to the high-pressure circulation from the wingtip. Kind of like sticking your hand out of the car window. The endplate is resisting the pressure under the wing from moving out into the undisturbed air while at the same time preventing the higher pressure undisturbed air from flowing onto the low pressure upper wing surface. There is competing energy at the wingtip. The endplate keeps the energy bottled until it meets after the wing when the respective air pressure energy must equalize. You can imagine what’s happening in the wing wake. Some sort of ugly drag.

The Thorp wing addresses this vortex issue by canting the outboard wing section.

Longer wings that taper tend to reduce vortex pressure. Imagine a wing that tapers to infinity and creates zero vortex since the pressure is equalized at the tip.

So, does any of this make much difference for a Sonerai with its vibrating fuselage skin? Probably not much unless you are looking to build a world record machine and your build quality is nearly perfect.

 

[kennyw]

Just thinking about the "ultimate" Sonerai, I was wondering if optimizing cooling drag and going with a cowled exhaust, rather than the exposed stacks might be the biggest efficiency gains (rather than worrying about wing tips).

Also, I was wondering if the Sam James pressure recovery wheel pants might make a difference.

 

[tls258]

Suggest reading this by Robin Austin, if not already:
http://www.worldrecordplane.com/aircraft-development-story

 

[Schmleff]

Just thinking about the "ultimate" Sonerai, I was wondering if optimizing cooling drag and going with a cowled exhaust, rather than the exposed stacks might be the biggest efficiency gains (rather than worrying about wing tips).

Also, I was wondering if the Sam James pressure recovery wheel pants might make a difference.

I have a set of Sam James pants. They are on the to do list, but I can tell you that the build quality was horrible. It took a lot of hours just to get them to fit together straight and smoothly.

 

[kennyw]

I have a set of Sam James pants. They are on the to do list, but I can tell you that the build quality was horrible. It took a lot of hours just to get them to fit together straight and smoothly.

I'd just like to see if there are any airspeed gains by cleaning up the gear/leg interface. I have a sneaking suspicion that 4SP could benefit from a better fitting pair of wheel pants.

 

[Bil4381]

When I bought my Sonerai IILS I got it into my mind that I needed to incorporate every mod I liked. 7 years later It had not flown. A lifetime friend who'd owned 50 aircraft, said do only what it needs to fly now. It flew that year. Once I'd flown it all the mods I wanted went out the canopy.: Useless. Installed scoop to provide ram air for the engine intake.
Power became important installed a Jabiru 3300 solid lifter engine at 127hp at 3300 rpm and 200 MPH. That required a bigger fin and bigger rudder. The engine now has fuel injection.
It's just amazing in flight. I installed a 5" ball slip indicator and foreflight on IPad. There is no such thing as map reading in an S2 at 200 mph.
Ultimate Sonerai? It is for me.
Bill E

Just thinking about the "ultimate" Sonerai, I was wondering if optimizing cooling drag and going with a cowled exhaust, rather than the exposed stacks might be the biggest efficiency gains (rather than worrying about wing tips).

Also, I was wondering if the Sam James pressure recovery wheel pants might make a difference.

 

[kennyw]

When I bought my Sonerai IILS I got it into my mind that I needed to incorporate every mod I liked. 7 years later It had not flown. A lifetime friend who'd owned 50 aircraft, said do only what it needs to fly now. It flew that year. Once I'd flown it all the mods I wanted went out the canopy.: Useless. Installed scoop to provide ram air for the engine intake.
Power became important installed a Jabiru 3300 solid lifter engine at 127hp at 3300 rpm and 200 MPH. That required a bigger fin and bigger rudder. The engine now has fuel injection.
It's just amazing in flight. I installed a 5" ball slip indicator and foreflight on IPad. There is no such thing as map reading in an S2 at 200 mph.
Ultimate Sonerai? It is for me.
Bill E

I'd be curious to know your Sonerai's empty weight is. What about aerobatic gross? Are you just limited to utility category? Do you have the higher max gross (1150 I think)?

I don't do any snap rolls or negative Gs. But loops and rolls are a must! I've never pulled more than 4Gs (according to my fancy G meter). Just because I know that with only 5 gallons of gas, I'm still right at the 750lb aerobatic max gross limit.