Aerodynamic modifications

[Curt_B]

Re: Aerodynamic modifications

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"....

From the pictures, with the rear lip out of plane to the front entrance, that would aerodynamically be classified as a scoop, disguised as a NACA inlet. Wouldn't provide a benefit over Strega's splitterless scoop, I would think, that can be used on a stock Mustang. Remember Tsunami having problems getting ram rise with their induction NACA inlet and reverted to a scoop. NACA inlets are good for cabin ventilation though when the canopy seals are loose giving potential for lots of flow through.

[RAD2LTR]

Re: Aerodynamic modifications

From the pictures, with the rear lip out of plane to the front entrance, that would aerodynamically be classified as a scoop, disguised as a NACA inlet. Wouldn't provide a benefit over Strega's splitterless scoop, I would think, that can be used on a stock Mustang. Remember Tsunami having problems getting ram rise with their induction NACA inlet and reverted to a scoop. NACA inlets are good for cabin ventilation though when the canopy seals are loose giving potential for lots of flow through.

I think Tsunami's issue with the NACA intake was that the carb was too close to the right angle turn from the scoop. MA2 apparently got it to work quite well due to the different placement of the carb. It was lower allowing the air to smooth out before entering the carb.

As for the radiator scoop, I know the MA2 guys got it to work well. I wasn't sure if the gear would get in the way of running one on a normal winged Mustang or not. It makes sense that no one else had tried one.

Its really too bad that a few of the promising designs never had the chance to fully realize their potential. Stiletto was fast with what sounds like a relatively stock motor, imagine if it had either Strega's or Voodoo's engine now, along with 20 years more development. Tsunami seemed like it was just about where it needed to be when it crashed. MA2 seems like it had a lot of promise but again was lost before it was really dialed in. Still there is hope that someday Tsunami will make its return. Granted it will again require sorting out but I think the concept was there. Still, since the whole thing needs to be rebuilt, it would make sense to change things that have since been proven less than optimal and again built it to match the current course requirements. I guess time will tell.

Will

[Curt_B]

Re: Aerodynamic modifications

Tsunami's NACA induction inlet was losing M.P. in the turns from what I remember. Wouldn't recommend it. MAII's radiator pod to house the quas-NACA inlet would be less efficient than Strega's splitterless scoop since the air has to go around it instead of through it, promoting a local region of crossflow. Have only seen photos of MAII in flight with the exit doors open, and would question it's success, unless someone can say it had tremendous speed for the period or something.

Anyone know why Rear Bear has that little triangular piece at the wing root leading edge. I think it's intended to break up the horseshoe vortex.

[John]

Re: Aerodynamic modifications

Anyone know why Rear Bear has that little triangular piece at the wing root leading edge. I think it's intended to break up the horseshoe vortex.

...was wondering the same thing, unless it is there for high alpha vortex?

IMHO Dago had the cleanest looking radiator scoop(sans splitter). Strega's is slightly different with a small ridge. Some of the photo dudes have posted interesting pics of Strega's scoop area during racing; one can see the oil flow streaks diverted around this ridge area. Almost looks like it is acting as a partial boundary layer splitter(?)

[Curt_B]

Re: Aerodynamic modifications

...was wondering the same thing, unless it is there for high alpha vortex?

IMHO Dago had the cleanest looking radiator scoop(sans splitter). Strega's is slightly different with a small ridge. Some of the photo dudes have posted interesting pics of Strega's scoop area during racing; one can see the oil flow streaks diverted around this ridge area. Almost looks like it is acting as a partial boundary layer splitter(?)

Or maybe it's a step to check the oil. Sailplane guys don't like vortices because it screws up the laminar flow. Link is a neat paper on wing/fuselage interference, depicts the horseshoe vortex, and talks about the Arnold AR-5 a little too.

http://www.scribd.com/doc/96021406/Design-Rules-Regarding-Wing-Body-Junction-Flows

The vortex generator aspect can't be discounted, and the local upwash from the wing is enough to generate one that would be stronger in the turns. Maybe they had a little seperation at the T.E. Seems like it'd hurt for compressibility reasons - making the wing look fatter there and all, but it will keep the flow attached longer. Aerodynamics is an art - I don't care who you are.

Could you find a picture of Dago's scoop. I've seen versions of Dago with the splitter, and a modified splitter. The small ridge on Strega's scoop is to shave off/accelerate the ingested boundary layer. Would still get some duct rumble, but that can be fixed obviously. Thought I saw oil flow streak diversion, but couldn't find it when I went back and looked, or it was less severe. Could you include some photos. Probably ones I missed. Ridge Runner was faster in 2009(?) because of the splitterless scoop. I think it did 450, or so, in 2005 with the splitter scoop version, and 490 in 2009 with the Strega type scoop.

[Smee Again]

Re: Aerodynamic modifications

Ridge Runner was faster in 2009(?) because of the splitterless scoop. I think it did 450, or so, in 2005 with the splitter scoop version, and 490 in 2009 with the Strega type scoop.

The scoop on RRIII in 2009 was pretty close to an exact copy of the Dago scoop, not Strega's. The radiator setup was also quite different to what Strega uses. The 2005 version of RRIII's scoop/cooling setup is the same as Precious Metal is currently using, which produced speeds of 465-ish during the Gold race that year (prior to a piston melting down on lap 3). While RRIII's dramatic speed increase from 2005 to 2009 had much to do with the scoop/cooling setup, there were several other factors contributing to the increase in performance, most of which lived under the hood. But getting that oil cooler out of the doghouse was a HUGE factor in adding, I'd guess, at least 12-15 MPH.

SA

[John]

Re: Aerodynamic modifications

Could you find a picture of Dago's scoop. I've seen versions of Dago with the splitter, and a modified splitter. The small ridge on Strega's scoop is to shave off/accelerate the ingested boundary layer. Would still get some duct rumble, but that can be fixed obviously. Thought I saw oil flow streak diversion, but couldn't find it when I went back and looked, or it was less severe. Could you include some photos. Probably ones I missed. Ridge Runner was faster in 2009(?) because of the splitterless scoop. I think it did 450, or so, in 2005 with the splitter scoop version, and 490 in 2009 with the Strega type scoop.

Post #3 here: http://www.aafo.com/hangartalk/showt...here-Reno-Pics -is interesting; showing the underbelly of Strega with some oil streaking. Not sure if some of that is just dirt(?) ...oops! generally Strega is super clean, so that is probably indeed oil, not dirt.

Dago should be in Wayne's 2003 Reno Forum thread. ?

[John]

Re: Aerodynamic modifications

Could you find a picture of Dago's scoop.

...for some reason I'm having trouble finding the good old photos, but here's a start: http://www.aafo.com/hangartalk/showt...urday-s-racing shows Dago 2004. There were some great photos of Dago in the day by the super Photographers who we are blessed to have attend this site.

[Curt_B]

Re: Aerodynamic modifications

Post #3 here: http://www.aafo.com/hangartalk/showt...here-Reno-Pics -is interesting; showing the underbelly of Strega with some oil streaking. Not sure if some of that is just dirt(?) ...oops! generally Strega is super clean, so that is probably indeed oil, not dirt.

Dago should be in Wayne's 2003 Reno Forum thread. ?

Thanks. Have an even more oily Strega photo more local to the scoop, Pulled it off the web, but don't know if somebody would object to me posting it here. There's a lot more going on with Strega on the backend. Was this the fast Dago Red scoop with the modified splitter in Fig 16 of;

http://www.warbirdaeropress.com/NewGallery/DagoRedBuilding/index.html

[RAD2LTR]

Re: Aerodynamic modifications

Post #3 here: http://www.aafo.com/hangartalk/showt...here-Reno-Pics -is interesting; showing the underbelly of Strega with some oil streaking. Not sure if some of that is just dirt(?) ...oops! generally Strega is super clean, so that is probably indeed oil, not dirt.

Dago should be in Wayne's 2003 Reno Forum thread. ?

Here are a few shots I took showing some leaks of some sort. The streams do take an interesting split at the scoop


you can't see much in the way of leaks with this but it shows the underside nicely.


Here is an interesting look at the scoop and strake profiles of Strega, Voodoo and PM.




Will

[John]

Re: Aerodynamic modifications

Thanks. Have an even more oily Strega photo more local to the scoop, Pulled it off the web, but don't know if somebody would object to me posting it here. There's a lot more going on with Strega on the backend. Was this the fast Dago Red scoop with the modified splitter in Fig 16 of;

http://www.warbirdaeropress.com/NewG...ing/index.html

There's some guys who attend this site with much greater knowledge of Dago's history. Specifically that looks like the very early Dago(1982), but I do remember in '93 it had a different set up(very squarish inlet). Must be sometime during the 90's they changed it to the much more efficient looking splitterless small inlet design. The afterbody looked cleaned up also. One other thing I always liked about Dago Red is the stock looking horz. stab. No clip. Chopped edges don't look all that efficient. Would one square off the main wing and expect it to be efficient? ...Trivial(since it's the stab), I know...

[John]

Re: Aerodynamic modifications

Here are a few shots I took showing some leaks of some sort. The streams do take an interesting split at the scoop


you can't see much in the way of leaks with this but it shows the underside nicely.


Here is an interesting look at the scoop and strake profiles of Strega, Voodoo and PM.




Will

Very cool! Voodoo actually doesn't look bad. Thanks for those photos. Looks like some kind of boundary layer diversion around the scoop for sure on Strega. So does that indicate clean airflow to the tunnel?

[Curt_B]

Re: Aerodynamic modifications

Thanks for the under belly photos. Haven't seen some of them. You can tell the difference between the scoops. Looks like Strega's is generating a little stagnation around the lip and it's causing the boundary layer air to go around. Might need a little touch-up aerodynamically.

There's some guys who attend this site with much greater knowledge of Dago's history. Specifically that looks like the very early Dago(1982), but I do remember in '93 it had a different set up(very squarish inlet). Must be sometime during the 90's they changed it to the much more efficient looking splitterless small inlet design. The afterbody looked cleaned up also. One other thing I always liked about Dago Red is the stock looking horz. stab. No clip. Chopped edges don't look all that efficient. Would one square off the main wing and expect it to be efficient? ...Trivial(since it's the stab), I know...

The tail's making a lot of lift at these speeds all the way around the course. Induced drag is a function of span, as opposed to aspect ratio, and the short span of the tail coupled with it's high downward lift is generating a significant amount of tail induced drag. Never understood why everybody shortened their tails, unless their analysis says otherwise. I suspect the Mustang guys did it because it was a simple mod, and maybe didn't think it through.

Link is some simple aero principles, including wing tips;

http://www.zenithair.com/stolch801/design/design.html

[hm66sk]

Re: Aerodynamic modifications

Roundy spinners are best because the air flowing around them accelerates early and the pressure integration produces a thrust. The pointy spinner delays the acceleration toward the back end of the spinner and can see how that would incrementally lower the pressures at the 'smile'.

Thanks for answering a question I have been meaning to ask here and has perplexed me for years. One would think the pointy spinner would be more aerodynamic not thinking about how it affects intake pressure to the "smile"and its toll on MP. Makes total sense now and I understand why they use the stocker. The pointy ones though, to quote Jimmy Leeward, "Sure look sexy." They really do put the final hot-rod racey touch on a Mustang.

[hm66sk]

Re: Aerodynamic modifications

Speaking of interesting mutations of the P51, MA2 had some creative ideas for lowering drag such as the NACA ducts for both the carb intake and for the radiator scoop. According to the book "Griffon Powered Mustangs" once they had a few things sorted out, both worked very well. Will

Awesome thread. Love this technogeek ****. Lets me live vicariously through you guys that are there. Tsunami started with a NACA scoop then switched to a standard intake ala P-51A. Apparently the NACA didn't work so well for them. Sandberg chose a downdraft system like the Griffons though right? Any info on both these changes and why?