Author Topic: Northrop F-15A Reporter - NACA - Ames Laboratory  (Read 2374 times)

Offline Logan Hartke

  • High priest in the black arts of profiling...
  • Rivet-counting whiffer
Northrop F-15A Reporter - NACA - Ames Laboratory
« on: April 18, 2014, 02:57:08 AM »
Finished another "real world" profile today.  This one required a lot of work to do the drop test object, something there weren't great references for.  As always, click on the image below to see the picture at 100% or view it at my DeviantArt page.



The last flying example of the entire P-61 line was a rare F-15A Reporter (RF-61C) (s/n 45-59300), the first production model Reporter to be built. The aircraft was completed on 15 May 1946, and served with the Army Air Corps and later the U.S. Air Force until 6 February 1948, when it was reassigned to the Ames Aeronautical Laboratory at Moffett Field in California for transonic aerodynamic research. Interest in the transonic flight regime increased markedly after the Second World War, reflecting further attempts to increase aircraft performance. However, wind tunnels of the time were inadequate for carrying out this kind of research. In one approach to acquiring transonic aerodynamic data, heavily weighted models of the configuration of interest were dropped from high altitudes. In those tests, which were conducted at Edwards Air Force Base, aerodynamic bodies that were to be evaluated in the transonic flight regime were released from an aircraft at altitudes up to 43,000 feet. The instrumented bodies would pass through the transonic speed range in free fall, during which they were oscillated through a range of angles of attack and were then decelerated and recovered by means of air brakes and parachutes. Testing at these altitudes was arduous and, although the pilots wore heavy flight suits, the model drops were made on the first run to reduce the pilots' exposure to the extreme cold.



The F-15A-1-NO aircraft, a reconnaissance model of the P-61 night fighter, was reconfigured to serve as a launch vehicle for these tests. The high-altitude capability of the F-15A made it the ideal "mother ship" for this work. An aircraft similar to this one, an ERF-61C, owned by the Smithsonian Institution, was lent to Ames to be used in this program as well. Pilots who participated in this work were George Cooper, Rudolph (Rudy) Van Dyke, Don Heinle, and Fred Drinkwater. As with the wing-flow tests, qualitative results were obtained; nevertheless, the advent of the new transonic tunnels supplanted flight testing as a means of documenting the aerodynamics of this flight regime. The air-brake and parachute systems developed for these tests were subsequently used by many agencies for rocket and satellite payload recovery. In April, 1955, the F-15A was declared surplus along with a "spare parts" F-61C (s/n 43-8357).



Here's a closeup of the nose showing the new pitot, new camera window, new rivet pattern, new panels and panel lines, and new bottom camera fairing.  In short, basically a new nose again.  I feel like a plastic surgeon on this plane, I'm doing so many nose jobs.



Cheers,

Logan

Offline GTX_Admin

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Re: Northrop F-15A Reporter - NACA - Ames Laboratory
« Reply #1 on: April 18, 2014, 03:23:16 AM »
 :)
All hail the God of Frustration!!!

Offline Logan Hartke

  • High priest in the black arts of profiling...
  • Rivet-counting whiffer
Re: Northrop F-15A Reporter - NACA - Ames Laboratory
« Reply #2 on: April 18, 2014, 03:34:39 AM »
In case anyone wanted to see the process of how I put this one together, I've show some of the progress below.



At this first "in progress" image, I've actually already done a lot of the work.  I've done much of the recontouring of the nose and I've gotten the markings largely finished.  Despite that, there's still a LOT of work left to do.



Here I redid the bulge on the upper nose, chipped the paint on the anti-glare panel, added the copy of the markings above the lighting to show the reduced shine on paint vs NMF, and have largely gotten the aircraft itself finished.  With the exception of the new pitot, it just needs the transonic test body.



At this stage, I'm just defining the primary shape and scale of the test body.  You'll also notice that I keep it level with the fuselage.  This is to aid in the sectioning of the shape, lighting, and a number of other elements.  Since it's basically symetrical, it's much easier to keep it level until the very end.



I still haven't started the lighting and shading of the body, yet, but you can see that the painting of it is largely done.  I've also removed the reference image.  I still consult it during the process, but I don't need it as much since the shape and scale are clearly defined.



Shaded, angled, and attached.  The straps were actually a pain since there are no good detail shots of them or the attachement points.  I tried to put them in the right place, then guess at their details.



All that's left now is the new pitot.  This is where I left it last night.



The new pitot was a couple hours of work, most of that research.  Still a pain.  The P-61 family had at least 3 completely different pitots on the nose among the variants.

Cheers,

Logan

Offline Logan Hartke

  • High priest in the black arts of profiling...
  • Rivet-counting whiffer
Re: Northrop F-15A Reporter - NACA - Ames Laboratory
« Reply #3 on: April 18, 2014, 03:58:11 AM »
Finally, someone on What If requested a comparison of the noses and the differences between them.  I'll show all three (XP-61F, XF-15A, F-15A).

You can see a number of differences.  The panel lines are different, the panels themselves have to be separate along panel lines into different layers, different camera windows (both side and bottom), different bulges on the top of the nose, different anti-glare panels, different cockpit windows, different pitots, different lighting, different shading, etc.







Also, I have to say, these are likely not 100% right.  There aren't fantastic, up close, authoritative references for these, so I had to guess based off what I had.  The left and right side of the nose are different, as well, so all the close ups of the right side are no good.  There's no surviving F-15 Reporter variant, so you can't use museum aircraft, either.  Also, XP-61E Prototype #1 and XP-61E Prototype #2 had different noses, the XF-15 Prototype and the XF-15A Prototype had different noses, and the F-15A Reporter production aircraft had a different nose from any of those, as well.  Yeah, bit of a nightmare sometimes.

Cheers,

Logan

Offline buzzbomb

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Re: Northrop F-15A Reporter - NACA - Ames Laboratory
« Reply #4 on: April 18, 2014, 07:45:25 AM »
Really nice stuff.

Offline taiidantomcat

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Re: Northrop F-15A Reporter - NACA - Ames Laboratory
« Reply #5 on: April 19, 2014, 05:57:30 AM »
Great guesses!  :)

Learn something new everyday, I had never seen this aircraft before, and some profiling info  :)

"They know you can do anything, So the question is, what don't you do?"

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Offline Dr. YoKai

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Re: Northrop F-15A Reporter - NACA - Ames Laboratory
« Reply #6 on: April 20, 2014, 09:03:22 AM »
 The Reporter was a terrific way for the Widow to bow out. Power and elegance in a silver package. Beautiful
 job all around, Logan.

Offline Logan Hartke

  • High priest in the black arts of profiling...
  • Rivet-counting whiffer
Re: Northrop F-15A Reporter - NACA - Ames Laboratory
« Reply #7 on: April 20, 2014, 01:13:39 PM »
Thanks, guys!  It was a beautiful subject and the transonic drop object provided an interesting item to add to this profile.  I only intend to use it on this profile, so if anyone wants to use it, let me know and I can get you the layers!

Cheers,

Logan