Aerodynamic modifications

[John]

Re: Aerodynamic modifications

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,

See also(for Rare Bear @post #677 "Down but not out"): http://www.aafo.com/hangartalk/showt...K-SHOTS/page68

[Curt_B]

Re: Aerodynamic modifications

See also(for Rare Bear @post #677 "Down but not out"): http://www.aafo.com/hangartalk/showt...K-SHOTS/page68

Cutting the corner off at the trail edge is a good idea to get rid of that surface. Have to be careful that it's thin though. The tip of the rudder looks better, and the little Yak's wingtips are Cub-like and better, and thin.

[Curt_B]

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/

I guess the induction must be under cowling. And it had a little strake.

[shadow]

Re: Aerodynamic modifications

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

wow, really?

I'm not saying you're wrong, not in the least, just that I'm rather surprised. Is this because the airliners cruise at 30,000 feet and need more AoA to get the lift at those lower densities and that racers are so much lighter that they have lower wing loadings?

There's so much discussion about how wing clips hurt performance in the turns but, adequately designed, you could have a much smaller wing than current unlimited racers.

I understand it's all a compromise but it kinda sounds like the better compromise would be a smaller wing....

[Curt_B]

Re: Aerodynamic modifications

wow, really?

I'm not saying you're wrong, not in the least, just that I'm rather surprised. Is this because the airliners cruise at 30,000 feet and need more AoA to get the lift at those lower densities and that racers are so much lighter that they have lower wing loadings?

There's so much discussion about how wing clips hurt performance in the turns but, adequately designed, you could have a much smaller wing than current unlimited racers.

I understand it's all a compromise but it kinda sounds like the better compromise would be a smaller wing....

10-4. The airliners maximize M*(L/D)/sfc, and they're designed for high M and CL. As they burn fuel, they want to cruise climb, or step climb, to maintain that high CL. The racers maximize M, or speed, and the rest of that equation is just a fall-out, except for maybe minimizing drag. You're correct about the smaller wing. Getting it by clip is the wrong way though, but anything other would require a new design. If you halve the wing area, you double the CL, and since the unlimiteds are already experiencing compressibility in the turns, that higher CL will hurt bad. Rear Bear especially would benefit with a longer wing, giving more wing area and span, just to bring the CL down in the turns to lower the compressibility drag. Something that could be looked at.

Of course reducing wing area on a given weight airframe would result in increased landing speed. Setting the wing area for landing would consider touching down midfield on Reno's shortest runway on speed, with a 10 knot tailwind, say, and being able to stop in the runout area with a healthy pilot and airframe.

[Samuel]

Re: Aerodynamic modifications

10-4. The airliners maximize M*(L/D)/sfc, and they're designed for high M and CL. As they burn fuel, they want to cruise climb, or step climb, to maintain that high CL. The racers maximize M, or speed, and the rest of that equation is just a fall-out, except for maybe minimizing drag. You're correct about the smaller wing. Getting it by clip is the wrong way though, but anything other would require a new design. If you halve the wing area, you double the CL, and since the unlimiteds are already experiencing compressibility in the turns, that higher CL will hurt bad. Rear Bear especially would benefit with a longer wing, giving more wing area and span, just to bring the CL down in the turns to lower the compressibility drag. Something that could be looked at.

Of course reducing wing area on a given weight airframe would result in increased landing speed. Setting the wing area for landing would consider touching down midfield on Reno's shortest runway on speed, with a 10 knot tailwind, say, and being able to stop in the runout area with a healthy pilot and airframe.

I guess September Fury would be the one to prove this since they are using the long wings now? I think when it won Reno though it did have the short wings.

I also found this interesting article on the H-1 Racer. I had no idea there was two sets of wings: http://blogs.airspacemag.com/daily-p...e-me-look-fat/

[Wild Bill Kelso]

Re: Aerodynamic modifications

A little fact about the PM wingtips. They are more than meet the eye. A little more "treatment" than you know.

[Samuel]

Re: Aerodynamic modifications

Not sure if this has been posted here, but here is a hypothetical for beating the shock waves on Dago Red. Maybe it could be added to Precious Metal's super tips.

http://aero-comlab.stanford.edu/kasi...aa.06-0048.pdf

[Curt_B]

Re: Aerodynamic modifications

I guess September Fury would be the one to prove this since they are using the long wings now? I think when it won Reno though it did have the short wings.

I also found this interesting article on the H-1 Racer. I had no idea there was two sets of wings: http://blogs.airspacemag.com/daily-p...e-me-look-fat/

Clipping the Sea Fury wings adds drag faster than clipping a Mustang say, due to the planform. Compressibility might be better with the Sea Fury's due to the thinner sections, but I haven't checked. Clipping them inboard, like for the racer, Shockwave, essentially, is a better idea. For flat out, 1g speed, clip is good since CL is below 0.1 and the wing is making minimal lift. So for the world record speed runs, in the H-1's case, clip makes sense, or just a shorter wing in this case. For the Bearcat case, as much of that slow airfoil you can get rid of, the better, for the 1g all out speed run.

[Curt_B]

Re: Aerodynamic modifications

A little fact about the PM wingtips. They are more than meet the eye. A little more "treatment" than you know.

They add more stability due to the L.E. sweep and span extension. Had an excellent opportunity for a little more, free, stability if they would have come off the top wing skin straight out for that particular style and let the lower surface cant up spanwise, but probably isn't needed. The, new, Boeing style would give similar stability results.

Good stuff guys!

[Curt_B]

Re: Aerodynamic modifications

Not sure if this has been posted here, but here is a hypothetical for beating the shock waves on Dago Red. Maybe it could be added to Precious Metal's super tips.

http://aero-comlab.stanford.edu/kasi...aa.06-0048.pdf

Thanks, think we talked about this earlier in the thread. The bump is a single design point design and would be detrimental for the multiple design point flight conditions the racers experience, and result in the much dreaded double shock wave forming for off-design. Better suited for a speed run, but the model was in error. Anyway, there's a better way of doing it and the shock is further inboard than at the tips.

Good stuff.

[Wild Bill Kelso]

Re: Aerodynamic modifications

They add more stability due to the L.E. sweep and span extension. Had an excellent opportunity for a little more, free, stability if they would have come off the top wing skin straight out for that particular style and let the lower surface cant up spanwise, but probably isn't needed. The, new, Boeing style would give similar stability results.

Good stuff guys!

I'm going to say it one more time! You do not know what they are. Don't belittle the work and effort that went into them.

[Curt_B]

Re: Aerodynamic modifications

I'm going to say it one more time! You do not know what they are. Don't belittle the work and effort that went into them.

Misunderstanding, would assume they're of the highest quality, and Ya'll should be proud.

Alright guys, you racer fans must be the best fans out there. I know I pull for the racers and crews to do the best that they can, and by indications Y'all do too. It's good the races are still around.

It's hard to remember to come over here and check on statements every now and then, but I'd feel bad abandoning the ones that have an open-minded interest in this subject. Since this is a public forum and all, I've set up an email that'd be easier to monitor, and thwart any stalkers that come this way, lol.

Aero_stuff1@yahoo.com

Thanks for the interest - learned some stuff - keep it up.

[Curt_B]

Re: Aerodynamic modifications

Oh, forgot the christmas poem for that one person that hasn't seen it yet. Y'all have a good holiday. I'll be removing the 40 year old fabric from my Chipmunk, if the hangar's not too cold - always fun to see what's been hiding for so long - almost like opening up a Christmas present.

'Twas Night Before Christmas

'Twas the night before Christmas all over the place,
When we were confronted by an old flying ace.

There was icing reported and turbulent air,
He said, "File me a flight plan, I gotta get there."

Outside sat his aircraft all ready to run,
And the old man walked out to that P-51.

"Bad weather's no problem," he silently mumbled,
The prop came to life; that big Allison rumbled.

He eased in the throttle, the roar shook the ground,
He taxied on out and he turned it around.

He went through the run-up and seemed satisfied,
Then he said to himself, "I'm in for a ride."

So he lined it up straight as he poured on the coal,
The tailwheel came up as he started to roll.

Up off the runway, he sucked up the gear,
And that mighty V-12 was all you could hear.

He screamed overhead with a deafening crack,
The blue flames were flying from each shiny stack.

He pulled up the nose and started to climb,
No ice on that airframe, it didn't have time.

On top of the weather with the levers all set,
He looked up above him and saw a Lear jet.

With jet fuel and turbines there just ain't no class,
Gimmee pistons, and props and lots of avgas!

Now he was approaching where he wanted to go,
But weather had covered the runway with snow.

How will he land it? We just have to guess,
Because the only way in was a full I-L-S.

Then over the marker, he started his run,
The ceiling was zero, visibility. . . none.

Still going three hundred and he felt the need,
For an overhead break to diminish his speed.

Over the numbers he zoomed, along like a flash,
Pulled into his break, he just knew he would crash.

Oh, why do they do it on these kind of nights?
Then over the threshold, he saw landing lights.

"I'm on a short final with three in the green,
And I see enough runway to land this machine."

Then he tied down that Mustang, and they all hear him say. . .
"Next year, I'm stickin' with my reindeer and sleigh."