Mig-PAK FA T-50 Prototype Evolution

1/15/2015 Update

Dave Backmaker, a regular contributor to our blog, had some great comments he posted on my blog about printing on Depron.  I "painted" my plane and took it to the print shop yesterday.  The "mainframe" will be double side printed on Depron.  The fuselage will printed on MPF.  I like to use MPF on the fuselage because it is easier to mold and sand than Depron. The KFs will be printed on Dollar Store Foam.  I leave town for a week so there won't be an update on the final print until I get back. The guys at the print shop are as excited as I am.  Here are jpgs of the PDFs:

Earlier I posted a video on my latest prototype build.  After further development of the design, I thought I'd post an update.

I definitely need to figure out a better name for this "hybrid" plane.  Perhaps simply the Mig-FA.  It's kind of like putting a small block Chevy in a  channeled & chopped custom 32 Ford roadster.  More on the design after some background.

The Russian military PAK-FA (Prospective Airborne Complex of Frontline Aviation) project was a fifth generation fighter program focusing on stealth technology.  In 2000, Mikoyan-and-Gurevich Design Bureau designed a stealth plane, the MiG 1.44/1.42, that was an evolution of the Mig-37.  The Mig1.44/1.42 flew in 2000 but never made it to production:

Sukhoi went on to design and build the T-50:

In the search for "stealthiness" there are many aerodynamic comprises.  Stealth design leaves little airflow over the vertical stabilizers as the horizontal stabilizer is coupled to the wing trailing edge.  With that comes bad slow speed tendencies at high angles of attack as there is no gap between the wing and horizontal stabilizer for air "leak" through and onto the vertical stabilizers.  Additionally, the vertical stabilizers are angled therefore the rudders cause pitch in addition to yaw further complicating surface control input commands.   I wanted a stealth plane as I really like the look,  so I built the RCP F-22v3 and quickly learned why as stealth plane is such a handful to fly. Real planes are loaded with computer assisted flight controls.   At slow speeds, the F-22 would violently yaw and then pitch into the ground.  As long as I was flying 50% throttle and above it was blast.

So after 8 months of developing the ultimate Mig "chassis" (stay tuned, more to come), I decided to do some old fashioned hot rodding and make a stealth plane.  I started with the fit, finish and design of Scott's and mine ultimate Mig and went back to the computer and started drawing.  Borrowing a proven Ford chassis, I added a Chevy carriage.   Using diagrams, photos, and plans from the internet on the T-50, I redrew a new stealth plane around our new ultimate Mig chassis.

Technical drawing that was the inspiration for prototype #1:

Protoype #1:

The T50 is 65 ft long divided by wingspan of 45.8 ft  = 1.41. My prototype is 38" long and 27” wide = 1.407.

The fuselage in the picture above was a left over design experiment the ultimate Mig project.  The plane flew amazingly well and had a great profile in the sky so I moved forward with the project.  It did not have the undesirable characteristics of the F-22, even with its coupled tail and "hidden" vertical stabilizers except for at near stall speeds.  I spent another 30 hours or so moving pixels in my drawing program (iDraw vector drawing program for Mac) and building Dollar Store foam board fuselages to try and improve the look.  

I started with this side profile photo to improve the look and made several builds:

Forming and shaping the nose has always been difficult, so I added a forward piece to stringer:

Final fuselage in profile and same with a drawing:

From a design standpoint the radar extension on the tail is polarizing.  This area of the elevons is very important in parkjets for thrust vectoring, especially in high alpha.  Prototype #1 had excellent thrust vectoring control, I think it was due to a combination of right amount of square area and the centrally located radar extensions which minimized the roll lever arm.  For prototype #2, I also drew elevons without the radar extension, but I maintained the same square area in the thrust vectoring zone. For the final plans, this will be an option.  

Tailplane with thrust vectoring square area measurements:

Elevon options with and without radar extension:

Schematic of plane without fuselage:

Next phase of the project is "painting" the plane in the drawing program and  Iwill print it directly onto Depron as with these plans:

Hopefully the weather will clear and it get in some more test flights on prototype 2.  My case of Depron came in today.  Quick aside on my builds, I use MPF for the canopy and fuselage as it sands better than Depron.  The rest of the build is Depron.  Another Ford & Chevy hybrid?

I think I'll call this plane simply the Mig-FA.

Stephan