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NAA P51 D-5 NA-1/18 scale
- Thread starter Geo
- Start date
The next step is to sand the stacks into the required shape, such that, they fit the fuselage apertures properly without losing all the angles. Its a real witches itch to do. I had to repeat this building process several times to get it to come out properly. It was quite exasperating and I had to just walk away from it it more than once to relieve the frustration.
Fortunately both sides were achieved. Dummy rod stock of proper diameter was placed(.125")to check alignment.
The acid test of whether or not they sit properly in the fairing aperture. Note that because ofthe nose taper, the fairings protrude more at the front than they do at the rear.
The carb air breather plates shown here were CNC machined by a friend.
The fairings will be left out until the nose is terminally joined to the center section. Thats about it for the exhaust stack fairings. If anyone would like more information please feel free to ask.
Cheers,
Geoff
Fortunately both sides were achieved. Dummy rod stock of proper diameter was placed(.125")to check alignment.
The acid test of whether or not they sit properly in the fairing aperture. Note that because ofthe nose taper, the fairings protrude more at the front than they do at the rear.
The carb air breather plates shown here were CNC machined by a friend.
The fairings will be left out until the nose is terminally joined to the center section. Thats about it for the exhaust stack fairings. If anyone would like more information please feel free to ask.
Cheers,
Geoff
just went through your posts, that is modelling engineering to the max, really nice work Geoff!
Hi Phil,
Glad you looked in and thank you for your kind comments. This has turned out to be a real heavy lift build and promises to offer more challenges down the road. I must admit, Im loving this more than any build Ive ever done and the size of it is just spectacular. It has tremendous presence and the detail options are unlimited.
I really want to post photos of the entire fuselage assembled but Im waiting until I cover the empennage to maintain proper order. The tail assembly, I think is the biggest challenge because of what needed to be done, and while not scratch built, its damn close to it and the challenges were myriad. Youll see what I mean soon...
Geoff
IF it had been me, i would have taken the shortcut and left the stack fairing off, but then again, the results would not be as pretty as what you have here. 
I guess you did profile templates to get the shape of the fairings sanded to shape?
Must be nice to have a CNC friend :drinks
I guess you did profile templates to get the shape of the fairings sanded to shape?
Must be nice to have a CNC friend :drinks
IF it had been me, i would have taken the shortcut and left the stack fairing off, but then again, the results would not be as pretty as what you have here.
I guess you did profile templates to get the shape of the fairings sanded to shape?
Must be nice to have a CNC friend :drinks
Hi Moon,
Thanks for looking in and your kind compliment. The fairing isnt as complex as it looks. If you look at it its just a ninety-three (93) degree angle. I used the NAA drawings as a reference and made a simple single template from litho plate to check the angle while sanding. The front and rear radii center on the intersection of the two flat surfaces.
A friend that did this rebuild chose the unshrouded exhausts. He said making the twelve stacks made him want to shove a sharp stick in his eye. It also required building something to mount the stacks to. That wasnt easy either but he got it done without inflicting self harm.
Indeed, having someone with CNC capability is a big help sometimes. I'm going to have him do the MLG doors but that's it. The rest will be hand built as it has been thus far. Having a full set of NAA Engineering Drawings is a huge advantage when needing information on parts. Another huge asset is the P-51 SIG. The guys there are a remarkable brain trust of Mustang knowledge and have gladly helped me immeasurably.
This project has just enthralled me. The size of it is impressive and allows all sorts of detail possibilities. I hope you'll continue to follow. Please ask any questions you might have. I'm more than willing to share.
Cheers
Geoff
Yeah we use to have a "prototype" (3d) printer at work. Then something broke and an engineer attempted to fix it...kid never soldiered anything in his live and thought he could do a PCB on a controller, nevermind we have an onsite electrical maintenance guy who does that stuff all the time...the kid toasted the printer. 
Never did get the chance for them to make something for me.
I can echo the P-51 SIG, they were tremendous help for me when I did my Iwo Jima Tamiya P51, of course I did mine before Tamiya released the kit with the dual antenna already in the box, again...
Now I know you've posted there, I'm not going to go peak, I'm along for the ride like everyone else here
Never did get the chance for them to make something for me.I can echo the P-51 SIG, they were tremendous help for me when I did my Iwo Jima Tamiya P51, of course I did mine before Tamiya released the kit with the dual antenna already in the box, again..
. Now I know you've posted there, I'm not going to go peak, I'm along for the ride like everyone else here
Yeah we use to have a "prototype" (3d) printer at work. Then something broke and an engineer attempted to fix it...kid never soldiered anything in his live and thought he could do a PCB on a controller, nevermind we have an onsite electrical maintenance guy who does that stuff all the time...the kid toasted the printer.
I can echo the P-51 SIG, they were tremendous help for me when I did my Iwo Jima Tamiya P51, of course I did mine before Tamiya released the kit with the dual antenna already in the box, again..
Now I know you've posted there, I'm not going to go peak, I'm along for the ride like everyone else here
Thanks Moon...Id love to try one of those 3D printers, but Im also a bit of a dinosaur and prefer to build my own stuff. Stay the course here. Theres much more to come...
Hi Barney,
Thanks for looking in and your kind comment. I can only hope Ill be able to hold your interest.
Cheers
Geoff
Greetings All,
I guess now is the best time to begin the empennage. Mind you, its close to being complete so this is more a retrospective than a real time narrative.
Initial impressions, and keeping in mind that this is, in large measure a toy, the tail section represented the first real trouble point. If I couldnt get past this, the entire project would come to an end.
There are no factory drawings of the fuselage. Hence, the drawings of Charles Neely were used to evaluate the fuselage throughout. Mr. Neelys drawings have been analyzed extensively for shape accuracy and found to be spot on. They are not as technically presented as Mr. Bentleys drawings, but Bentleys drawings do have some geometry issues and a couple of real clunker mistakes which, for me, tends to erode confidence in them. I felt my best chance for not only accuracy, but also success would be in Charlys drawings. Hes also a member on the 51 Sig and always helpful as is everyone else.
The fuselage as a complete assembly, prior to sectioning, was laid out on the plans which I had adjusted at a local printer. Initially I was shocked to find there was very little deviation in shape. Of course there was no way to see lateral section accuracy but longitudinal geometry was pretty good, but the were problem areas. Issues with the nose and position of the cockpit sill were initially addressed. After looking at this for a bit, it struck me that this all looked very familiar. I pulled a Trump 24th scale (dreadful thing that it is)
Mustang from the shelf and compared it to a 24th scale set of Neely drawings. It turned out to be exactly the same as the 18nth scale offering, right down to the oddly bulged canopy.I dont know which came first, but I would suggest they are somehow related.
Where it really became obvious was at the back end from STA 248 and aft. Dr Frank Mitchell, a notable builder in his own right, noticed this problem when he built the 24th Trump offering, but he thought the cockpit was too far aft. As a result, he moved the cockpit section forward to get it visually more acceptable.
Hence, upon aligning features of the nose and wind screen directly on the drawing, the cockpit was found to be correctly positioned as was everything else forward of STA 248. Even the panels splits aligned properly with the drawing.
I have no idea why the back end is so far out. The length deficiency is .270" at STA 248. This is a big, big error. This deficiency throws everything out of position. Obviously the fuselage would have to be stretched the deficient amount in order to bring everything into alignment.
This is the initial evaluation. The deficiency is decidedly obvious and it all starts at STA 248. The question now became how to stretch the fuselage and maintain alignment between between the resulting pieces. Add to this my desire to build a D-5 (earliest production version) which would require removal of the dorsal fin fillet (DFF) and it was rapidly becoming a job of rather large proportion.
The stretch at 248 brought things nicely, but not completely into alignment.
I marveled at the impact that one little cut had and wondered what caused these different companies to make this mistake. Im certain Ill never know.
These are the three points of alignment to insure accuracy.
There are several other issues that needed to be addressed aside from the LOA issue. The main issue at this point was stretching the fuselage and whether or not I wanted to get involved in such a major undertaking.
I guess now is the best time to begin the empennage. Mind you, its close to being complete so this is more a retrospective than a real time narrative.
Initial impressions, and keeping in mind that this is, in large measure a toy, the tail section represented the first real trouble point. If I couldnt get past this, the entire project would come to an end.
There are no factory drawings of the fuselage. Hence, the drawings of Charles Neely were used to evaluate the fuselage throughout. Mr. Neelys drawings have been analyzed extensively for shape accuracy and found to be spot on. They are not as technically presented as Mr. Bentleys drawings, but Bentleys drawings do have some geometry issues and a couple of real clunker mistakes which, for me, tends to erode confidence in them. I felt my best chance for not only accuracy, but also success would be in Charlys drawings. Hes also a member on the 51 Sig and always helpful as is everyone else.
The fuselage as a complete assembly, prior to sectioning, was laid out on the plans which I had adjusted at a local printer. Initially I was shocked to find there was very little deviation in shape. Of course there was no way to see lateral section accuracy but longitudinal geometry was pretty good, but the were problem areas. Issues with the nose and position of the cockpit sill were initially addressed. After looking at this for a bit, it struck me that this all looked very familiar. I pulled a Trump 24th scale (dreadful thing that it is)
Mustang from the shelf and compared it to a 24th scale set of Neely drawings. It turned out to be exactly the same as the 18nth scale offering, right down to the oddly bulged canopy.I dont know which came first, but I would suggest they are somehow related.
Where it really became obvious was at the back end from STA 248 and aft. Dr Frank Mitchell, a notable builder in his own right, noticed this problem when he built the 24th Trump offering, but he thought the cockpit was too far aft. As a result, he moved the cockpit section forward to get it visually more acceptable.
Hence, upon aligning features of the nose and wind screen directly on the drawing, the cockpit was found to be correctly positioned as was everything else forward of STA 248. Even the panels splits aligned properly with the drawing.
I have no idea why the back end is so far out. The length deficiency is .270" at STA 248. This is a big, big error. This deficiency throws everything out of position. Obviously the fuselage would have to be stretched the deficient amount in order to bring everything into alignment.
This is the initial evaluation. The deficiency is decidedly obvious and it all starts at STA 248. The question now became how to stretch the fuselage and maintain alignment between between the resulting pieces. Add to this my desire to build a D-5 (earliest production version) which would require removal of the dorsal fin fillet (DFF) and it was rapidly becoming a job of rather large proportion.
The stretch at 248 brought things nicely, but not completely into alignment.
I marveled at the impact that one little cut had and wondered what caused these different companies to make this mistake. Im certain Ill never know.
These are the three points of alignment to insure accuracy.
There are several other issues that needed to be addressed aside from the LOA issue. The main issue at this point was stretching the fuselage and whether or not I wanted to get involved in such a major undertaking.
Yikes! Not only short but it also seems to be angled differently or is that just lens effect of your camera?
Sta numbers are based on inches from the nose correct?
Sta numbers are based on inches from the nose correct?
Paulw
Well-known member
I agree that this will be quite the undertaking Geoff and I wonder if you will be able to bring everything back into alignment. Quite a few people would question your dedication to this but I think it is an endeavor to display your talents and I for one am watching some one who can do the things that I do not have the patience to do. I applaud you and am following this really closely. I love it.
ij001
Well-known member
Paul just covered a lot of what I was going to write. In my opinion, it's a huge testament to our hobby, that such diverse disciplines all exist side-by-side (for most part in harmony).
Like Joe's P-40, Randy's F4U and Chuk's IAR, there's fantastic and inspirational 'dedication to the cause' here, really enjoying watching the process. Keep it coming, Geoff.
Ian
Like Joe's P-40, Randy's F4U and Chuk's IAR, there's fantastic and inspirational 'dedication to the cause' here, really enjoying watching the process. Keep it coming, Geoff.
Ian
Sherman 18
Master at Arms
I am enjoying your build B)
Yikes! Not only short but it also seems to be angled differently or is that just lens effect of your camera?
Sta numbers are based on inches from the nose correct?
Hi Moon,
Youre correct in your assesment of the off verticle rudder post. If you look closely at the photo, you'll see that the aft end, once translated to its new position, is now wider and deeper than the drawing. It was in this excess dimension that I was able to find room to pivot the entire assembly to make up for the rudder post discrepancy. Another issue I didn't mention earlier was the badly mishappen bottom pan. Removing it, along with the DFF gave me plenty of sway to make up for the rudder without compromising shape or scale fidelity.
Youre largely correct about the STA positions. STA positions are referenced to the zero (0) station which is usually someplace close to the nose. In the case of the Mustang, STA 0 is located about a foot behind the very end of the cowling. The number associated with each STA is the number of inches aft of zero (0) station.
station numbers in front of zero station have a negative value.
I'm glad you're following. Feel free to ask anything of critique.
Cheers
Geoff
Greetings Paul,
I'm glad you looked in. The empennage assembly is nearing completion. I must say is was quite a projects and couple probably fill its own build thread. You said the magic word in your comment...patience. This project requires it by the boat load. It also requires recalibtating ones thoughts processes in terms of time. Things that you might normally spend hours on now require a time investment of days,weeks, months, and dare I say...years. In short, you're creating the kit so you can build it. Most is prep work to make sure everything is as it should be before committing to the manufacture of the part.
I could go on ad nauseum about this but Ill stuff a sock in it so as not to make you nuts. Just know I do very much appreciate your looking and hope you'll continue to do so.
Best
Geoff
Thank you Ian. I appreciate your sentiment and hope you'll continue to follow. Comments, questions and critique are always welcome.
Cheers
Geoff
