Material Challenge for Drag Reduction

I would go with feathers....

My thinking exactly! But you are the Eagle and should know best.

Now you only have to find out how to claim your price money!

That may be a good answer. biomimicry has been shown to be very efficient for some things. maybe the pattern on eagles wings could form a good pattern for a riblet design. The current problem with Riblets is that they clog up with dirt, ice and insect splatter losing their effectiveness. Is their anything in eagle feathers that could help with this? if so provide the proof in a white paper and it may get accepted.

thanks for your input

Isn't drag essentially a function of form and finish? And with the subject being legacy aircraft, form is already established thus leaving only finish... polish the CR4P out if it.

Seriously though, there is drag as a function of lift... can't do much with that as 'lift' is a thing with planes so I'm told.

Then there is wave drag, but we're talking transport aircraft so have to assume they're all sub-sonic so that's essentially a non-issue.

This leaves skin friction... parasitic drag, which brings us back to polishing. Sure there are issues with panel interface, fastener head flushness, etc. but what percentage of decrease in drag are you likely to achieve at this level of influence?

Doesn't sound like a good ROI to me...

But who knows, many much smarter people will likely have some brilliant ideas - unfortunately I'm not one of them.

Edit: Thanks for the post though, and welcome to CR4.

You are correct about keeping a material smooth. part of the problem is that it gets roughed up in flight. Also things like Riblets that induce a small amount of turbulence have been shown to reduce drag by 3 to5%. We don't need much to get an ROI depending on how easy it is to apply. All of what is known is detailed in the link I sent so you can check it out.

Thanks for your interest.

CR4 is starting to look like a revenue source for prize money. I wanna be a reality star too!

I love the part about " at your own expense"

Award Winners will be invited (at their expense) to a Technical Interchange Meeting in Dayton, Ohio, on 20 October 2015, to present their approach in greater detail and explore the ROI of their approach to the USAF legacy transport aircraft. Promising approaches will be further invited to submit a full proposal with selected winners receiving subcontracts to further mature and validate their technologies.

If you are an award winner you will get $10,000. I think AF thinks that for the prize you can come to Dayton. (but there is an option to attend via Skype or WebEx). They just want the best ideas.

They just want the best ideas!

Aha!

Good luck!

How about a development from the "Shark skin" ideas that help modern swimmers pass through the water better, or even the golf ball dimples that the Mythbusters used some years ago with seemingly great results...?

See here:-

Shark Skin Effect

Or here:-

Car with Dimples!!

Shark Skin was the original inspiration for riblets. they have been proven to reduce drag but they clog up with debris from prolonged flight. if you have an idea on keeping them clean submit your concept to the challenge site: https://gw.innocentive.com/ar/challenge/9933776