Aerodynamic modifications

[xmh53wrench]

Re: Aerodynamic modifications

I dont know squat about all of this, but how much of all this stuff is applicable to straight and level high speed, then how much is thrown right out the window when you put a race plane in a hi speed hi bank turn? Nevertheless really cool and interesting stuff guys.....

[RAD2LTR]

Re: Aerodynamic modifications

I dont know squat about all of this, but how much of all this stuff is applicable to straight and level high speed, then how much is thrown right out the window when you put a race plane in a hi speed hi bank turn? Nevertheless really cool and interesting stuff guys.....

I think this is exactly what WBK and the PM guys asked then set about answering. They then went on to make the aerodynamic aids to optimize the plane for just such a course. With a year to test and refine, as well as get the engine built, next year should be very interesting especially if they can shake the black cloud of doom.

I wonder if any of the other teams are watching and taking notes as to what the PM guys are trying to do. My guess is no, they will continue to run what has won in the past, until they get beaten then they will be playing catch up. As its been said, 2nd place sets the pace, until they pass and win the race. If the PM guys get a break, big things could happen next year.

Will

[Wild Bill Kelso]

Re: Aerodynamic modifications

I think this is exactly what WBK and the PM guys asked then set about answering. They then went on to make the aerodynamic aids to optimize the plane for just such a course. With a year to test and refine, as well as get the engine built, next year should be very interesting especially if they can shake the black cloud of doom.

I wonder if any of the other teams are watching and taking notes as to what the PM guys are trying to do. My guess is no, they will continue to run what has won in the past, until they get beaten then they will be playing catch up. As its been said, 2nd place sets the pace, until they pass and win the race. If the PM guys get a break, big things could happen next year.

Will

Only one goal for next year. A solid engine! This one was OK, but it was really down on power in a big way.

[Curt_B]

Re: Aerodynamic modifications

I dont know squat about all of this, but how much of all this stuff is applicable to straight and level high speed, then how much is thrown right out the window when you put a race plane in a hi speed hi bank turn? Nevertheless really cool and interesting stuff guys.....

In Rear Bear's case as an example, reducing compressibility drag would provide a benefit for the turns and the straights. The Mustangs are still pretty good in the straights, but they're nibbling at compressibility in the turns, so the goal there would be to manipulate the shock in the turns, with minimal impact on the straights. Either way, maintaining energy in the turns will help overall lap times. The mod performance enhancements applied to improve subsonic performance, like PM's extended wingtips, are additive in the compressibility case.

[taglialavore]

Re: Aerodynamic modifications

May I think about this in applying Richard Whitcomb´s Area Rule?
When those guys were struggling with high speed drag, they fell in that rule, and I think it worked well.
I`m just thinking in loud voice.

[taglialavore]

Re: Aerodynamic modifications

May I think about this in applying Richard Whitcomb´s Area Rule?
When those guys were struggling with high speed drag, they fell in that rule, and I think it worked well.
I`m just thinking in loud voice.

[Wild Bill Kelso]

Re: Aerodynamic modifications

May I think about this in applying Richard Whitcomb´s Area Rule?
When those guys were struggling with high speed drag, they fell in that rule, and I think it worked well.
I`m just thinking in loud voice.

I have heard that removing the scoop off a Mustang at these speeds screws with the area rule.

[xmh53wrench]

Re: Aerodynamic modifications

Damn I wish I was smart....this stuff is fascinating! WBK, do you think that theory still applies to a Mustang rounding the pylons at Reno? I wish I knew more (actually anything at all really) about the gains if any that were made by Stiletto and GG's scoopectomys.

[Curt_B]

Re: Aerodynamic modifications

May I think about this in applying Richard Whitcomb´s Area Rule?
When those guys were struggling with high speed drag, they fell in that rule, and I think it worked well.
I`m just thinking in loud voice.

It's ok to think that way, especially for Rear Bear. Pretty sure they know what they're up against and have heard about a new, extended leading edge designed to decrease the t/c of the root section and smooth the upper surface curvature changes to mitigate compressibility drag. A good way to smooth out the area rule would be by shaping the canopy, if they haven't already.

The Mustang radiator housing looks like it'd smooth out area rule, but you have to remove the cross section of the duct, of the air going through it to calculate area rule. What you have left is the thickness if the structure that contributes to aera rule. It's more important to get smooth cross sectional area changes and minimal cross section area around the fuselage station of the shock location.

The main benefit of removing the radiator scoop and afterbody is eliminating the drag of the boundary splitter on the scoop, and the afterbody drag. It's true the internal flow produces a thrust on the Mustangs due to the Meredith effect of heating the air, but that thrust is overcome by the external flow drag of the scoop and afterbody fairing, so removal is a benefit.

[RAD2LTR]

Re: Aerodynamic modifications

It's ok to think that way, especially for Rear Bear. Pretty sure they know what they're up against and have heard about a new, extended leading edge designed to decrease the t/c of the root section and smooth the upper surface curvature changes to mitigate compressibility drag. A good way to smooth out the area rule would be by shaping the canopy, if they haven't already.

The Mustang radiator housing looks like it'd smooth out area rule, but you have to remove the cross section of the duct, of the air going through it to calculate area rule. What you have left is the thickness if the structure that contributes to aera rule. It's more important to get smooth cross sectional area changes and minimal cross section area around the fuselage station of the shock location.

The main benefit of removing the radiator scoop and afterbody is eliminating the drag of the boundary splitter on the scoop, and the afterbody drag. It's true the internal flow produces a thrust on the Mustangs due to the Meredith effect of heating the air, but that thrust is overcome by the external flow drag of the scoop and afterbody fairing, so removal is a benefit.

With this known, what about the NACA duct that MA2 ran for the scoop? It seems like it eliminates the boundary splitter, and looks like it might have cleaned up from the afterbody fairing. Sort of a 50% solution between scoopless and the normal one. The mod has always kind of intrigued me. I've always wondered if it lowered the drag enough to really be worth doing. No one else has tried it but again was that due to having something that works pretty well already or did the design not make a big enough difference for it to matter?

Will

[Curt_B]

Re: Aerodynamic modifications

With this known, what about the NACA duct that MA2 ran for the scoop? It seems like it eliminates the boundary splitter, and looks like it might have cleaned up from the afterbody fairing. Sort of a 50% solution between scoopless and the normal one. The mod has always kind of intrigued me. I've always wondered if it lowered the drag enough to really be worth doing. No one else has tried it but again was that due to having something that works pretty well already or did the design not make a big enough difference for it to matter?

Will

NACA scoops were originally devised for jet intakes that suck the air in. Use for radiator type applications that require efficient pressure recovery slows the air coming in, reducing the vortex action on the sides of the NACA scoop. The creation of these vortices on the sides of the NACA scoop is what draws outside air into the scoop. The link is the old NACA report. Read the section titled, 'Field of use for Submerged Inlets.'

http://naca.central.cranfield.ac.uk/report.php?NID=2176

They look cool though, and have probably sold a few cars over the years.

[1:1 Scale]

Re: Aerodynamic modifications

Stiletto and GG's scoopectomys.

I like to call them "fastbelly 'stangs"

[AAFO_WSagar]

Re: Aerodynamic modifications

With this known, what about the NACA duct that MA2 ran for the scoop? It seems like it eliminates the boundary splitter, and looks like it might have cleaned up from the afterbody fairing. Sort of a 50% solution between scoopless and the normal one. The mod has always kind of intrigued me. I've always wondered if it lowered the drag enough to really be worth doing. No one else has tried it but again was that due to having something that works pretty well already or did the design not make a big enough difference for it to matter?

Will

The space necessary to do a proper installation of a NACA on a stock Mustang is not there. The gear interferes with the distances necessary for the right sizing and ramping of the internal's.. MAII's wing was a Lear wing, lending it to be able to try this duct. According to the builders, it worked very well.

Link to story about the scoop published on the "way back machine"....

[grampi]

Re: Aerodynamic modifications

Maybe a good idea to get in touch with Gunther Balz?

Is he still alive? He used to fly his Bearcat over our house in MI when I was a kid. We lived out in the country and he would practice his aerobatics out there...fun to watch!

[Lockheed Bob]

Re: Aerodynamic modifications

Remember that there were 2 "scoopless" P51s racing @ the Cleveland Air Races in the 40s: 1. Anson Johnson with leading wing inlets for air.2. "Beguine" with wing tip radiators.