Aerodynamic modifications

[Curt_B]

Re: Aerodynamic modifications

About the 787 wingtips, doubt they studied birds for the design. They were driven by; reduced wing root bending moment provided by the reduced wing area out at the tip due to the narrow tip chord, reduced induced drag since airliners cruise at moderate CL's of 0.5 or so, and getting the shock to sweep at the tips to minimize wave drag. The first two are factors in bird evolution. The sweep also reduces profile drag in the subsonic, 'bird', domain. Those guys are pretty sharp though to figure all of that out.

You can do the same thing with winglets. Reducing the winglet tip chord to a minimum reduces the structural weight required to hang onto them.

[John]

Re: Aerodynamic modifications

Curt, I've not noticed a change in the Bear's wing tip treatment in many years, and our first year at Reno was '86. It looks like the current tips are the same. Very clean. Particularly nice looking in planform view.

Interesting info on the 787 raked tips.

[Curt_B]

Re: Aerodynamic modifications

Curt, I've not noticed a change in the Bear's wing tip treatment in many years, and our first year at Reno was '86. It looks like the current tips are the same. Very clean. Particularly nice looking in planform view.

Interesting info on the 787 raked tips.

Ok. I'll look at some recent pictures and get back to you. Since we're the only two talking here now, I'll just pm you so we can stay out of everybody's way. Thanks.

[CJAM427]

Re: Aerodynamic modifications

Ok. I'll look at some recent pictures and get back to you. Since we're the only two talking here now, I'll just pm you so we can stay out of everybody's way. Thanks.

I actually wouldn't mind hearing your thoughts on this too

[Curt_B]

Re: Aerodynamic modifications

I actually wouldn't mind hearing your thoughts on this too

Thanks. It's a little awkward sitting here just fielding questions like this though. I was raised a poor boy in Mississippi that appreciates simple things like my Cub that can just barely kill you. Lol. Wasn't doing this for my ego since I've learned to leave that behind, especially when flying - ego gets you killed in an airplane - for those that didn't know.

Would be great if anybody knows of an historical source for the lineage of the racers so I can wrap my simple mind on the aero mods over the years. Would be neat to create an evolution picture chart of the mods. Or maybe someone has already inadvertently compiled this by collecting photos over the years. If there's a book, I'll buy it if I knew what to look for. Also would be cool for people to contribute some photos of oil/dirt/condensation flow they might run across of all airplanes and classes. Cars are different and require a different understanding of aerodynamics so let's leave them out.

[badman]

Re: Aerodynamic modifications

yeah - I'm interested in hearing the rest of this discussion on-line. Also, I'm pretty sure the wing tips on Rare Bear haven't changed at all since they were first clipped way back when (late 60s?).

[Curt_B]

Re: Aerodynamic modifications

yeah - I'm interested in hearing the rest of this discussion on-line. Also, I'm pretty sure the wing tips on Rare Bear haven't changed at all since they were first clipped way back when (late 60s?).

The pics in;

http://www.aafo.com/hangartalk/showthread.php?11534-The-Heyday

show status in 1982, and is what I'm looking for generally. If anyone can point to similar links that'd be good. Rarebear tips appear to just be rounded and are nothing special from what I can see. From the above link, looks like Strega carried forward the strake from Sumthin' Else. The tip looks thinner on SE, was it clipped, and the scoops' stock. Dago has a tip treatment too. The original PM had moderate strakes, stock scoop, and reduced profile canopy? And Jeanne, did it end up on it's back in a landing accident in 80's, has another strake and a reduced capture area scoop. Was this scoop ever carried forward on another racer.

Thanks,

[L.E.D.]

Re: Aerodynamic modifications

I believe that Jeannie's 1980 accident was a belly landing; resulting in the scoop being replaced with the stock items. I don't know if it had been modified prior to that.

I'd be wiling to bet that Sumthin' Else's tips are a 'standard' production break clip, and that the pin-striping makes them look thinner.
Here's a pic of it when it was Miss Foxy Lady:

http://www.aafo.com/hangartalk/showthread.php?7834-Ken-Burnstine&p=76512#post76512

Little tidbit on the designers of some of the tip treatments:

http://www.aafo.com/hangartalk/showthread.php?2343-Photo-of-E-D-WEINER-mustangs&p=16615#post16615

[Curt_B]

Re: Aerodynamic modifications

I believe that Jeannie's 1980 accident was a belly landing; resulting in the scoop being replaced with the stock items. I don't know if it had been modified prior to that.

I'd be wiling to bet that Sumthin' Else's tips are a 'standard' production break clip, and that the pin-striping makes them look thinner.
Here's a pic of it when it was Miss Foxy Lady:

http://www.aafo.com/hangartalk/showthread.php?7834-Ken-Burnstine&p=76512#post76512

Little tidbit on the designers of some of the tip treatments:
http://www.aafo.com/hangartalk/showt...6615#post16615

Could of sworn, later, Jeannie had an engine failure and the landing resulted in the gear collapsing. Saw it on a trailer and thought it was totaled, it was so bent up, but my racing fan buddy said they'd have it flying next year. Remember it was polished aluminum and could have sworn it was Jeannie. Oh well, back before the internet I guess.

The Miss Foxy Lady photo explains a lot. I bet they dropped that tip for the one with fences for handling. With slight modification, that fancy tip would be better than it was.

Where is the carb intake on the Smirnoff Bearcat in;

http://www.enginehistory.org/Reno/EngineeringUnlimiteds120304.pdf

Thanks,

[L.E.D.]

Re: Aerodynamic modifications

A nice collection of Strega tip history:

http://www.aafo.com/hangartalk/showthread.php?11163-From-the-Wingman-archive

[Curt_B]

Re: Aerodynamic modifications

A nice collection of Strega tip history:

http://www.aafo.com/hangartalk/showt...ingman-archive

Nice. they got sooo close with the old Strega Cassidy tips for that style. Aileron effectiveness could have been improved with that style. Were the tips in the first photo similar to the original Griffon PM tips? Kind of funny how they flew a tip to just to see who would copy it. Lol.

Just to clear up some perceived misconceptions in that thread; airliners cruise at 0.75-0.82 Mach number and CL of 0.4 to 0.5. The unlimiteds are at 0.65 to 0.70 Mach nominally and CL's under 0.3 even at g, so they shouldn't be compared. The airliner wing is working harder at cruise than the unlimited wings are under g and the higher Mach number makes the design case even tougher. And the new PM wings tips are wing span extensions without special tip treatment, the planform shape of which originated from the C-5 in the 1960's to control shock unsweeping at the tips, if not sooner somewhere. The Mustangs have very little shock wave growth at the wingtips as it's more pronounced further inboard when it does develop.

Gotta figure out how to search these threads. Must be doing something wrong.

Thanks, I'm glad somebody knows how to.

Also, the airline manufacturers are currently concentrating on the wing since it takes so much effort to get that, right, and have been leaving the horizontal and vertical tip shapes to the designers who are stuck with text book, and internally developed methods. The current bird-like wing tips on the 787 could be applied to tail too with benefit.

Would think that about wraps it up for the wingtips, unless somebody knows something else. Looks like we have a pretty good understanding on the strakes. Didn't the Bearcat have strakes at one point.

[Curt_B]

Re: Aerodynamic modifications

It was Georgia Mae, not Jeannie.

http://www.ntsb.gov/aviationquery/brief.aspx?ev_id=20001214X37819&key=1

It looked like it had cartwheeled too. They got it flying the next year, however that happened.

[Samuel]

Re: Aerodynamic modifications

Where is the carb intake on the Smirnoff Bearcat in;

http://www.enginehistory.org/Reno/EngineeringUnlimiteds120304.pdf

Thanks,

Isn't it inside the cowling since it used the smaller 2800?

[Samuel]

Re: Aerodynamic modifications

[Samuel]

Re: Aerodynamic modifications

And more here with the cowling off:
http://www.flickr.com/photos/sdasmar...n/photostream/

http://www.flickr.com/photos/sdasmar...n/photostream/