4*60 Bash to P-51B
12-09-2009 | 01:16 PM
#1
4*60 Bash to P-51B
Just curious if anyone ever did this. I ran some preliminary numbers today, based on reducing the wing ribs outboard of the center to provide a mild LE sweep, and a somewhat more extreme TE sweep. Reducing the tip rib 50% so as to establish an outline based on the factory main spar locations, and using 2-1/2" aileron stock for the TE/Aileron (tapered to 1.5" at the tip), gives a tip chord of 7.5", a root chord of 13.75", and wingspan of 74" (1.5" block tips increased this from 71") The P-51B/C wing is really easy to bash from a "hershey bar" wing like the Star's, as it doesn't have that dog leg up next to the fuse, and the LE sweep seems less severe.
Wing area at all that would be around 786 square inches, not a huge reduction from the standard 920. Along with the reduction comes some weight loss as well, so wing loading shouldn't be terribly higher. I had one of these set up as a float plane, and it was really heavy, something like twelve pounds with the floats. It still flew really nicely, and when the floats were removed, it was still a floater on landing. (The float gear weighed maybe 2.5 pounds.)
The rest of the bash would be fairly straightforward: rounding of the turtledeck formers and sheeting that, along with some fiddling to get the aft cockpit window shape and location; fudging the tail feathers to Mustang outline; and making a belly scoop. The heaviest mods would be in the nose, which needs to be raised and rounded on top so that it can slope down towards the spinner, and rounded on the bottom to accept a Mustang shaped cowl. I want to stick with cheap plastic spinners, so I'd do the cowl for a 3", rather than a 4" which would be close to scale for this size airplane.
The wing can be easily reinforced to accept conventional fixed wire gear, and I think I'd use the Sig tailwheel setup for good ground handling, rather than a scale location.
I know my Magnum 91 FS would haul this thing around just fine, but I'd also have to put a ton of lead in the nose to get the CG, as the Stars are notoriously tail heavy. So......I'm thinking about using my 120AX two stroke, as it weighs 7-8 ounces more and can swing a much larger prop at a lower rpm. (16x8 at around 8200) This would give gobs of thrust without getting ridiculous on the top speed.
This is at the "design study" stage right now, as I have another Laddie Mikulasko Arrow on the board, but I'm pretty sure it will be my next project. I loved the way my old 4* flew, and I love Mustangs, which should be all too obvious. I'm also a huge fan of the 332nd Fighter Group, Lt. Lee Archer, and Gen. B.O. Davis.
Once I start building, I'll turn this into the build thread.
Wing area at all that would be around 786 square inches, not a huge reduction from the standard 920. Along with the reduction comes some weight loss as well, so wing loading shouldn't be terribly higher. I had one of these set up as a float plane, and it was really heavy, something like twelve pounds with the floats. It still flew really nicely, and when the floats were removed, it was still a floater on landing. (The float gear weighed maybe 2.5 pounds.)
The rest of the bash would be fairly straightforward: rounding of the turtledeck formers and sheeting that, along with some fiddling to get the aft cockpit window shape and location; fudging the tail feathers to Mustang outline; and making a belly scoop. The heaviest mods would be in the nose, which needs to be raised and rounded on top so that it can slope down towards the spinner, and rounded on the bottom to accept a Mustang shaped cowl. I want to stick with cheap plastic spinners, so I'd do the cowl for a 3", rather than a 4" which would be close to scale for this size airplane.
The wing can be easily reinforced to accept conventional fixed wire gear, and I think I'd use the Sig tailwheel setup for good ground handling, rather than a scale location.
I know my Magnum 91 FS would haul this thing around just fine, but I'd also have to put a ton of lead in the nose to get the CG, as the Stars are notoriously tail heavy. So......I'm thinking about using my 120AX two stroke, as it weighs 7-8 ounces more and can swing a much larger prop at a lower rpm. (16x8 at around 8200) This would give gobs of thrust without getting ridiculous on the top speed.
This is at the "design study" stage right now, as I have another Laddie Mikulasko Arrow on the board, but I'm pretty sure it will be my next project. I loved the way my old 4* flew, and I love Mustangs, which should be all too obvious. I'm also a huge fan of the 332nd Fighter Group, Lt. Lee Archer, and Gen. B.O. Davis.
Once I start building, I'll turn this into the build thread.
12-09-2009 | 07:07 PM
#2
RE: 4*60 Bash to P-51B
Hey Bob - thanks for the "fire starter" thread. Gotta do something to stay warm (-20 this AM).
Em - why <u>not </u>move the tailwheel forward. A simple pull-pull with a mini HS-81 "hidden" servo. Could run it internally and use a small servo-type hatch near the tailwheel. Gotta balance that 120AX.
You thinkin' "0" dihedral on the wing top with a couple of degrees on the bottom?
TTFN,
Em - why <u>not </u>move the tailwheel forward. A simple pull-pull with a mini HS-81 "hidden" servo. Could run it internally and use a small servo-type hatch near the tailwheel. Gotta balance that 120AX.
You thinkin' "0" dihedral on the wing top with a couple of degrees on the bottom?
TTFN,
12-09-2009 | 09:04 PM
#3
RE: 4*60 Bash to P-51B
Seamus:
I think I'm going to cut my outboard ribs with tabs front and rear, so that all the rib centerlines will be aligned, root to tip. That will make the wing a constant taper, top and bottom, more like the real 'stang. I have to go back and look at my old 4* plans again, but I think the dihedral they call for about matches the -51, which is what I want to do.
I hear ya on the weather, man. Not real cold here, but over a foot of snow since last night and more falling. We usually do about 120" a year, but it started late this time. None of the ski areas are open around here, yet.
I think I'm going to cut my outboard ribs with tabs front and rear, so that all the rib centerlines will be aligned, root to tip. That will make the wing a constant taper, top and bottom, more like the real 'stang. I have to go back and look at my old 4* plans again, but I think the dihedral they call for about matches the -51, which is what I want to do.
I hear ya on the weather, man. Not real cold here, but over a foot of snow since last night and more falling. We usually do about 120" a year, but it started late this time. None of the ski areas are open around here, yet.
