Aerodynamic modifications

[Curt_B]

Re: Aerodynamic modifications

Interesting... Last question I promise! -With Sea Furys, the common turtle deck seems to be the one 232 sports, versus one that blends to the tail like Furias's original one; since new Furias featured the 232 deck. Is there more drag introduced with a deck that ends well before the tail like on 232, versus Dago's deck?

Fire away. Fun commenting on details like this. Desirable pressure recovery on the ass end should be the goal. Reducing airframe volume decreases drag too, but if the close outs are too severe, the displacement thickness, or boundary layer growth, effectively increases airframe volume too. You just can't see it. Can you post pictures of the Furias and 232 decks. Remember, 232 has a longer fuselage than the 'Stangs, so dimensionally, 232's deck might be the same, or similar to Dago's in length.

[CJAM427]

Re: Aerodynamic modifications

Fire away. Fun commenting on details like this. Desirable pressure recovery on the ass end should be the goal. Reducing airframe volume decreases drag too, but if the close outs are too severe, the displacement thickness, or boundary layer growth, effectively increases airframe volume too. You just can't see it. Can you post pictures of the Furias and 232 decks. Remember, 232 has a longer fuselage than the 'Stangs, so dimensionally, 232's deck might be the same, or similar to Dago's in length.

Okay awesome! I'm asking because, 1 -I've always wondered about this stuff, and 2 I'm writing a novel for National Novel Writing Month about a fictional pilot who builds the ultimate P-51 racer and I want it to be as accurate as possible.

Here's Taichi's drawings of the two, I can post actual photos if you want...

[Curt_B]

Re: Aerodynamic modifications

Okay awesome! I'm asking because, 1 -I've always wondered about this stuff, and 2 I'm writing a novel for National Novel Writing Month about a fictional pilot who builds the ultimate P-51 racer and I want it to be as accurate as possible.

Here's Taichi's drawings of the two, I can post actual photos if you want...

2. Kind of like a Tom Clancy novel, only for air racing. Get me a copy. A dramatic finish during a heat race in the early/mid 80's was a guy in a Mustang trying to get past a Corsair low flying a perfect line. Lap after lap. He was high, and on the last last turn around pylon 8, banked past vertical, pulled, and dove for the win at the home pylon. The old codgers around me said that's how guys die in the Mustang and that he must have had both feet on the top rudder. Must have meant it since they were standing on tippy toes watching his recovery. I was just jumping up and down it was so cool. Lol.

The big turtle deck in the drawing is more like Voodoo/Strega/Czechmate. The added geometric volume, and unseen displacement thickness volume is undesirable and creates unnecessary drag. Looks pretty cool though. Also, the break in curvature at the top of the windscreen accelerates the air more than required and he could get Mach rumble, i.e. drag, up there at 500 mph.

Maybe the good people here can build the ultimate Mustang racer.

Some components I can think of,

Stock horizontal tips
Wing incidence for min fuselage drag
Tail incidence for zero average elevator deflection to minimize pressure darg
Aft cg
Splitterless scoop and oil duct cooler mod if not boil off
Advanced prop
Dago type turtle deck
Optimal wing span
Modified ailerons
Reflexed flaps/ailerons
Modified rudder
Wingtip treatment
Taped gaps
Sealed canopy/windscreen gap
Modified seat for the pilot's begonias
Minimum weight, i.e., paintless, bolts/studs the correct length, etc..., all the little stuff that adds up
Super secret classified unknown boundary layer thinning techniques. Lol
And whatever else I neglected to mention.

[CJAM427]

Re: Aerodynamic modifications

2. Kind of like a Tom Clancy novel, only for air racing. Get me a copy. A dramatic finish during a heat race in the early/mid 80's was a guy in a Mustang trying to get past a Corsair low flying a perfect line. Lap after lap. He was high, and on the last last turn around pylon 8, banked past vertical, pulled, and dove for the win at the home pylon. The old codgers around me said that's how guys die in the Mustang and that he must have had both feet on the top rudder. Must have meant it since they were standing on tippy toes watching his recovery. I was just jumping up and down it was so cool. Lol.

The big turtle deck in the drawing is more like Voodoo/Strega/Czechmate. The added geometric volume, and unseen displacement thickness volume is undesirable and creates unnecessary drag. Looks pretty cool though. Also, the break in curvature at the top of the windscreen accelerates the air more than required and he could get Mach rumble, i.e. drag, up there at 500 mph.

Maybe the good people here can build the ultimate Mustang racer.

Some components I can think of,

Stock horizontal tips
Wing incidence for min fuselage drag
Tail incidence for zero average elevator deflection to minimize pressure darg
Aft cg
Splitterless scoop and oil duct cooler mod if not boil off
Advanced prop
Dago type turtle deck
Optimal wing span
Modified ailerons
Reflexed flaps/ailerons
Modified rudder
Wingtip treatment
Taped gaps
Sealed canopy/windscreen gap
Modified seat for the pilot's begonias
Minimum weight, i.e., paintless, bolts/studs the correct length, etc..., all the little stuff that adds up
Super secret classified unknown boundary layer thinning techniques. Lol
And whatever else I neglected to mention.

Yeah something like that. I will definitely share it here once it's finished!

I think there was a thread on the ultimate racer at some point. Anyway for hypothetical purposes (the story is fiction) I would start with a P-51H because it had the thinnest profile wing.

On your mods
-Instead of a splitterless scoop, just go scoopless maybe?
Could you elaborate on the rudder, aileron and flaps mods?
Are the newest Precious Metal wingtips the best tips to use?

[RAD2LTR]

Re: Aerodynamic modifications

Interesting... Last question I promise! -With Sea Furys, the common turtle deck seems to be the one 232 sports, versus one that blends to the tail like Furias's original one; since new Furias featured the 232 deck. Is there more drag introduced with a deck that ends well before the tail like on 232, versus Dago's deck?

I think the bigger issue here is keeping the tailwheel where it belongs. When 232s came out early in lap 2 it was like someone tossed a big anchor out. It seemed like Voodoo up and ran away at that point. Even if everything else is perfect, a tailwheel flopping about in the breeze isn't going to do anything for your speed.

Will

[CJAM427]

Re: Aerodynamic modifications

I think the bigger issue here is keeping the tailwheel where it belongs. When 232s came out early in lap 2 it was like someone tossed a big anchor out. It seemed like Voodoo up and ran away at that point. Even if everything else is perfect, a tailwheel flopping about in the breeze isn't going to do anything for your speed.

Will

I would agree with you here. I was asking about this more for overall knowledge on what the best deck for a Fury is.

[Curt_B]

Re: Aerodynamic modifications

Yeah something like that. I will definitely share it here once it's finished!

I think there was a thread on the ultimate racer at some point. Anyway for hypothetical purposes (the story is fiction) I would start with a P-51H because it had the thinnest profile wing.

On your mods
-Instead of a splitterless scoop, just go scoopless maybe?
Could you elaborate on the rudder, aileron and flaps mods?
Are the newest Precious Metal wingtips the best tips to use?

Think I'd start with an A model fuselage since it sits down on the wing more. I like the
D wing planform and the H's thinner wing sections if it's not too heavy. The H's fuselage is draggy the way it sits up so proud and the steep close-out in the backend hurts.

Scoopless is fine. You'd still have fuselage afterbody drag though that should be addressed.

Aileron and flap mods are race secrets to the crew chiefs/team I'd imagine. You can just say they were modified for speed or something in the novel.

Nobody's doing it yet, but the rudder sweeps up at the bottom and creates blunt body drag locally due to closing out the thickness from the hinge line too rapidly.

PM's wingtips are wing span extensions. They can be improved to get the vortex out of the wing plane.

[CJAM427]

Re: Aerodynamic modifications

Think I'd start with an A model fuselage since it sits down on the wing more. I like the
D wing planform and the H's thinner wing sections if it's not too heavy. The H's fuselage is draggy the way it sits up so proud and the steep close-out in the backend hurts.

Scoopless is fine. You'd still have fuselage afterbody drag though that should be addressed.

Aileron and flap mods are race secrets to the crew chiefs/team I'd imagine. You can just say they were modified for speed or something in the novel.

Nobody's doing it yet, but the rudder sweeps up at the bottom and creates blunt body drag locally due to closing out the thickness from the hinge line too rapidly.

PM's wingtips are wing span extensions. They can be improved to get the vortex out of the wing plane.

That would work out good!
So a more pointy rudder, like a Sea Fury?

What about wing strakes, Strega-style?

[Curt_B]

Re: Aerodynamic modifications

That would work out good!
So a more pointy rudder, like a Sea Fury?

What about wing strakes, Strega-style?

More like this version of Furias.

An mph here, an mph there, and pretty soon you're talking MPH. Lol.

The strakes on Strega, and the truncated strakes on Voodoo do two things. The first is to scrape off the fuselage boundary layer that's been growing since the spinner - this makes the radiator fairing look smaller to the air. The second thing is that they create well defined vortices that scrub off the boundary layer further aft that the strakes miss. They also change pressure recovery favorably. Don't believe this was originally intended, but that's why they work. And hey, a hit is a hit. With the scoopless configuration, another approach is needed that is more of a distributed vortex pattern, and would be applicable for the Bearcat and Seafurys too. This pattern would also be useful for the air cooled radiator Mustang versions.

[CJAM427]

Re: Aerodynamic modifications

More like this version of Furias.[ATTACH=CONFIG]20371[/ATTACH]

An mph here, an mph there, and pretty soon you're talking MPH. Lol.

The strakes on Strega, and the truncated strakes on Voodoo do two things. The first is to scrape off the fuselage boundary layer that's been growing since the spinner - this makes the radiator fairing look smaller to the air. The second thing is that they create well defined vortices that scrub off the boundary layer further aft that the strakes miss. They also change pressure recovery favorably. Don't believe this was originally intended, but that's why they work. And hey, a hit is a hit. With the scoopless configuration, another approach is needed that is more of a distributed vortex pattern, and would be applicable for the Bearcat and Seafurys too. This pattern would also be useful for the air cooled radiator Mustang versions.

Again very interesting! -I have a lot of thinking to do now! May have to get my sketch pad out and draw up this super stang. Thank you for all your input!!!

[CJAM427]

Re: Aerodynamic modifications

I thought of another question! -I knew I hadn't put all of this to rest just yet!

How does Tsunami line up when talking about maximum aerodynamic efficiency?

Just taking a stab in the dark here, but would the deck on Tsunami not be the most optimum, as it just blends to the tail with no intersection to the body?

[Curt_B]

Re: Aerodynamic modifications

I thought of another question! -I knew I hadn't put all of this to rest just yet!

How does Tsunami line up when talking about maximum aerodynamic efficiency?

Just taking a stab in the dark here, but would the deck on Tsunami not be the most optimum, as it just blends to the tail with no intersection to the body?

Tsunami has the sharp line between the deck and the fuselage, so that's undesirable. The cockpit sits so far aft that it has to blend with the tail. Would also fair it back to the maximum thickness of the vertical to minimize the number of pressure gradients the air has to contend with, and to decrease the aft pressure gradient of the deck.

The scoop splitter dumps mostly behind the wing so it's effect on the lower surface wing trailing edge is better than the Mustangs. He could use the strake. High speed airfoils would have been desirable since it's scratch built to increase drag divergence Mach number and decrease wing weight. There was also a trade between airframe volume and fuselage close-out angle by shortening the fuselage behind the pilot. Fuselage afterbody drag pretty much goes away with the jets since there's a big hole back there. Another reason they go fast.

Designers make things look pretty, is a talent, and is a plus since good looking usually means fast, on top of layouts and integrating systems. The aero guys are needed for the external shape because the designers reach the limit of their knowledge, or what they can look up.

[CJAM427]

Re: Aerodynamic modifications

Tsunami has the sharp line between the deck and the fuselage, so that's undesirable. The cockpit sits so far aft that it has to blend with the tail. Would also fair it back to the maximum thickness of the vertical to minimize the number of pressure gradients the air has to contend with, and to decrease the aft pressure gradient of the deck.

The scoop splitter dumps mostly behind the wing so it's effect on the lower surface wing trailing edge is better than the Mustangs. He could use the strake. High speed airfoils would have been desirable since it's scratch built to increase drag divergence Mach number and decrease wing weight. There was also a trade between airframe volume and fuselage close-out angle by shortening the fuselage behind the pilot. Fuselage afterbody drag pretty much goes away with the jets since there's a big hole back there. Another reason they go fast.

Designers make things look pretty, is a talent, and is a plus since good looking usually means fast, on top of layouts and integrating systems. The aero guys are needed for the external shape because the designers reach the limit of their knowledge, or what they can look up.

That's all good to know!

It's too bad Tsunami had to end the way it did, it was just starting to reach it's potential...

[Curt_B]

Re: Aerodynamic modifications

That's all good to know!

It's too bad Tsunami had to end the way it did, it was just starting to reach it's potential...

That was a sad day. Still have a Tsunami jacket in my closet somewhere. Days go on for the rest of us though.

Anybody know the history of wingtips on the racers. You can get away with just squaring them off if the airfoil at the tip is thin, and/or the tip chord is short, like on a Mooney, at Mooney speeds. I've seen pictures of Dago with different tips. Which were the tips for the fast runs. The little upper and lower endplates on Voodoo/Strega help dissipate the wing vortex, but I suspect they were added to improve aileron effectiveness more than anything.

[Wild Bill Kelso]

Re: Aerodynamic modifications

That was a sad day. Still have a Tsunami jacket in my closet somewhere. Days go on for the rest of us though.

Anybody know the history of wingtips on the racers. You can get away with just squaring them off if the airfoil at the tip is thin, and/or the tip chord is short, like on a Mooney, at Mooney speeds. I've seen pictures of Dago with different tips. Which were the tips for the fast runs. The little upper and lower endplates on Voodoo/Strega help dissipate the wing vortex, but I suspect they were added to improve aileron effectiveness more than anything.

We had the same tips as Dago. They were the upswept/reverse horton... Whatever you call them. They had pretty bad spillover from the bottom of the wing that caused almost reverse airflow in the last 4-6 inches of the aileron.