Juggernut Posted December 7, 2019 Share Posted December 7, 2019 Since this subject has been debated ad nauseum both here and on other forums, I decided to contact the foremost authority on the P-51 Mustang, restorer of Happy Jack's Go Buggy, winner of numerous awards and the authenticity of the restoration; Midwest Aero on the subject of panel lines, fillers and visibility. Midwest Aero is THE place to go if you want an historically accurate, flyable P-51 restoration. It took them awhile to respond but below is my query to them and the response I received. These guys are the closest you can come to North American factory production processes and finishes and what the Mustang wing is supposed to look like when it's finished. My Question to the experts at Midwest Aero: Hello, If you have a few minutes, could you provide some information (settle an argument of sorts) on the P-51 wing putty, sanding and finishing? As the closest entity to how a Mustang was finished on the production line, I thought you folks would have the most accurate information on the process and finishing of the P-51 wing. Basically we have a disagreement about how the Mustang wing looked after finishing. Since the wing was puttied and sanded from leading edge to 40% chord, would panel lines (skin butt joints) still be visible after the finishing process ( at both 40% chord and aft)? My opposition will not accept factory photographs, nor written procedures from the structural repair manual. I am of the opinion that these "panel lines" would not be visible after the wing had been finished. Note that I realize that the MLG, fuel tank panels, and gun/ammunition panels/covers were not finished as the rest of the wing. The other opinion is that in spite of the sanding and filling, those "panel lines" would still be visible under the layers of primer, putty, and topcoats. I raised the question that visible panel lines would effectively defeat the point of filling them in the first place. I got no reply. I've read the structural repair procedure for leading edge wing damage which I feel supports my opinion. As a licensed aircraft mechanic (A&P- 32 years), I feel that I have a pretty good understanding on the how's, why's and how to's...but I cannot say with much degree of certainty that my position is the correct one as I have zero experience on the Mustang. Thanks for your time and any insight you can provide . Their Reply: To answer your questions, I agree with you. The panel lines would “disappear” basically where the filling took place. The only caveat would be after a period of time, it would not be out of the question that some panel lines might become somewhat visible due to wing flex and cracking of said fillers at those particular joints. Otherwise, overall my experience based on original photos and actually doing some of this work that the lines go away. I hope that helps! So, right from the guys who actually work on the Mustang wing (you'll most likely not find anyone any more experienced in this matter that is still with us)...the lines are not generally visible. FWIW, Jennings' graphic of the Mustang wing is as accurate as can be had regarding this issue. You just read it from the guys who work,restore and refinish Mustangs for a living. LSP_K2, CANicoll, Artful69 and 3 others 6 Link to comment Share on other sites More sharing options...
Radub Posted December 7, 2019 Share Posted December 7, 2019 (edited) This is like those "anti-vaxx" arguments all over the internet. Some people choose to listen only to what supports their "argument" and call everything else "fake news". I recommend that you look at ALL evidence of all kinds and from all sources, not just the stuff you like. Go near any Mustang anywhere in the world and make up your own mind. Look at ALL published photos. Look at ALL photos on the net. Do not ignore any evidence! One thing that will strike you is that from a distance the wing will appear smooth. But as you get close you will see the panel lines. Even this restorer admits that the panel lines make their appearance after a while. Jennings? Well, when "pressed" he said "I am not to blame if people misinterpret my drawing" - in other words he drew the panel lines on his drawing in "grey" instead of "black" and then allow the reader to interpret this ambiguity depending on the "panel line truther" camp they fall into. To me, the Mustang models with filled and sanded "wooden wings" look like no Mustang I ever saw up close. Radu Edited December 7, 2019 by Radub jimbo 1 Link to comment Share on other sites More sharing options...
quang Posted December 7, 2019 Share Posted December 7, 2019 Even panel lines re-appear on my 1/48th Mustang puttied wings after a while. A simple effect of contraction between different materials –plastic v.s. putty. All the more realistic. Alain Gadbois, LSP_K2, BiggTim and 1 other 3 1 Link to comment Share on other sites More sharing options...
Radub Posted December 7, 2019 Share Posted December 7, 2019 (edited) In as far as I understand, the Thunderbolt wings were supposed to be puttied and polished just like the Mustang wings. No one is making a fuss there... Apart from that, all models involve certain levels of compromise, ranging from subtle to outrageous (30 mm canopy glass anyone?). Here is the bad news, accuracy fans: no panel line on any model is "accurate" - if we were to make panel lines "to scale" they would be invisible even in 1/24. Those controversial panel lines on the real Mustang wings are no wider than the lines on the fuselage. You want "accuracy"? Why stop at the wings? Erase the fuselage panel lines too! Radu Edited December 7, 2019 by Radub Link to comment Share on other sites More sharing options...
Artful69 Posted December 7, 2019 Share Posted December 7, 2019 3 hours ago, Juggernut said: Since this subject has been debated ad nauseum both here and on other forums, I decided to contact the foremost authority on the P-51 Mustang, restorer of Happy Jack's Go Buggy, winner of numerous awards and the authenticity of the restoration; Midwest Aero on the subject of panel lines, fillers and visibility. Midwest Aero is THE place to go if you want an historically accurate, flyable P-51 restoration. It took them awhile to respond but below is my query to them and the response I received. These guys are the closest you can come to North American factory production processes and finishes and what the Mustang wing is supposed to look like when it's finished. My Question to the experts at Midwest Aero: Hello, If you have a few minutes, could you provide some information (settle an argument of sorts) on the P-51 wing putty, sanding and finishing? As the closest entity to how a Mustang was finished on the production line, I thought you folks would have the most accurate information on the process and finishing of the P-51 wing. Basically we have a disagreement about how the Mustang wing looked after finishing. Since the wing was puttied and sanded from leading edge to 40% chord, would panel lines (skin butt joints) still be visible after the finishing process ( at both 40% chord and aft)? My opposition will not accept factory photographs, nor written procedures from the structural repair manual. I am of the opinion that these "panel lines" would not be visible after the wing had been finished. Note that I realize that the MLG, fuel tank panels, and gun/ammunition panels/covers were not finished as the rest of the wing. The other opinion is that in spite of the sanding and filling, those "panel lines" would still be visible under the layers of primer, putty, and topcoats. I raised the question that visible panel lines would effectively defeat the point of filling them in the first place. I got no reply. I've read the structural repair procedure for leading edge wing damage which I feel supports my opinion. As a licensed aircraft mechanic (A&P- 32 years), I feel that I have a pretty good understanding on the how's, why's and how to's...but I cannot say with much degree of certainty that my position is the correct one as I have zero experience on the Mustang. Thanks for your time and any insight you can provide . Their Reply: To answer your questions, I agree with you. The panel lines would “disappear” basically where the filling took place. The only caveat would be after a period of time, it would not be out of the question that some panel lines might become somewhat visible due to wing flex and cracking of said fillers at those particular joints. Otherwise, overall my experience based on original photos and actually doing some of this work that the lines go away. I hope that helps! So, right from the guys who actually work on the Mustang wing (you'll most likely not find anyone any more experienced in this matter that is still with us)...the lines are not generally visible. FWIW, Jennings' graphic of the Mustang wing is as accurate as can be had regarding this issue. You just read it from the guys who work,restore and refinish Mustangs for a living. I agree ... stuff all was visible from 3 metres away on the two flying examples I saw ... and these dudes are restoration experts ... Good enough for me ... Thanks mate. Rog CANicoll and Troy Molitor 2 Link to comment Share on other sites More sharing options...
MikeMaben Posted December 7, 2019 Share Posted December 7, 2019 No offense but I didn't hear anything new. A basic knowledge of putty physics tells us that a puttied surface is smooth. The statement about stress seperation also makes sense and has been made many times. Still seems to be an issue open to degrees of variation . thierry laurent and Troy Molitor 2 Link to comment Share on other sites More sharing options...
Radub Posted December 7, 2019 Share Posted December 7, 2019 Let me make it clear that I believe Mustang wings were puttied and lacquered to a very smooth finish. Here is a photo I took of the Mustang on display in the RAF museum in Hendon. Note the smooth finish! Radu Gazzas and Martinnfb 2 Link to comment Share on other sites More sharing options...
Juggernut Posted December 7, 2019 Author Share Posted December 7, 2019 (edited) 4 hours ago, Radub said: Let me make it clear that I believe Mustang wings were puttied and lacquered to a very smooth finish. Here is a photo I took of the Mustang on display in the RAF museum in Hendon. Note the smooth finish! Radu This is the evidence you provide that Mustang's panel lines were still visible through putty, sanding, finishing from how far away, yet you refute factory photographs from less than 3 ft distance that are contrary to your position...that's just crazy! I've looked at ALL the photographs I can get my hands on and ALL the musuem examples I can access.... How dare you insinuate that just because my evidence supports my conclusion, I've ignored all the remainder! I even added to my email to Midwest Aero that I wasn't sure about my information since I had zero experience working on the airframe (as a licensed aircraft and powerplant aircraft mechanic). I can post photos of museum mustangs too! These are from one of the most prestigious museums in the world, the Smithsonian Air and Space Musuem.... No panel lines at rivet wing joints. And with that, I'm done being insulted and told my evidence is lacking....I don't feel the need to fight the "Right-at-all-costs" fight. What else can I do? I cannot go dig up and reanimate North American employees who actually finished the wings to get their experiences. There's no "in-the-crate" examples of P-51's to examine....Contact Midwest Aero yourself and listen to what the actual people who work these airframes tell you. Edited December 7, 2019 by Juggernut Link to comment Share on other sites More sharing options...
SB20 Posted December 7, 2019 Share Posted December 7, 2019 The problem is people want black and white when the world is grey. No one argues how the aircraft left the factory. Nice and smooth. Where the differences come in is over time how the aircraft evolves based on operational stresses. Environment, g-force stressing, etc....all will affect the initial finish. My car left the factory absolutely pristine, but it isnt now. As builders we need to remember there is so much variation over an aircraft's lifespan that the same aircraft can be built completely differently based on what time in it's life you've decided to model. Fresh from the factory, smooth as can be. Operating in the Pacific for awhile and been to depot maintenance a few times, probably gonna see the panel lines relatively well. Just build to what pictures you have and what makes you happy. Jack and Troy Molitor 2 Link to comment Share on other sites More sharing options...
Radub Posted December 7, 2019 Share Posted December 7, 2019 26 minutes ago, Juggernut said: This is the evidence you provide that Mustang's panel lines were still visible through putty, sanding, finishing from how far away, yet you refute factory photographs from less than 3 ft distance that are contrary to your position...that's just crazy! I am not ignoring anything. As I said to you, let us look at all evidence. Here are some photos of the same wing I took from up close: I also have photos of three other Mustangs I researched in Duxford.There was also a fourth Mustang I reasearched in Duxford, but I have to see if I have photos of the wings (This was taken apart - I looked at other area). I can upload them to Google Photos in the next day. These are photos I took, not stuff found on the net. If you wish I can upload them too, but let me assure you that they look pretty much the same as these photos above - the "look" is quite uniform across all airframes. Why do these panels appear? Flex? Shrinkage? I don't know. They just are there. I also recommend that you look at photos of "Lil' Margaret", an aircraft that was beautifully restored. From a distance the wings look perfectly smooth, but get close and you can see the panel lines. This aicraft features in the Aero Detail book as well as the beautiful book "P-51 Mustang Restored" by Paul Cogan. Radu Radu Martinnfb 1 Link to comment Share on other sites More sharing options...
Gazzas Posted December 7, 2019 Share Posted December 7, 2019 (edited) Next thing you know, somebody is gonna say that Mustangs didn't go to war all shiny, but with dull, matte aluminum that looks just like Alclad. Edited December 7, 2019 by Gazzas Martinnfb 1 Link to comment Share on other sites More sharing options...
dmthamade Posted December 7, 2019 Share Posted December 7, 2019 So, you say the thunderbolt wings were puttied and smoothed, anyone have pics of this? Maybe we should have a discussion? Thoughtful, civilized repartee? Link to comment Share on other sites More sharing options...
Radub Posted December 7, 2019 Share Posted December 7, 2019 Speaking of the Excalibur III in the Smithsonian, I have seen it a few times and I noticed something very interesting about it. Look for yourself in this photo from the Smithsonian's own website: https://airandspace.si.edu/collection-objects/north-american-p-51c-excalibur-iii All panel lines are almost eradicated, not just on the wings. This was a special experimental aircraft. Radu Martinnfb 1 Link to comment Share on other sites More sharing options...
rigor Posted December 7, 2019 Share Posted December 7, 2019 Looks like panel liNes to me but on another note never knew the wings where puttied On a thunderbolt I have a lot on a thunderbolt never seen this LSP_K2 1 Link to comment Share on other sites More sharing options...
Juggernut Posted December 7, 2019 Author Share Posted December 7, 2019 (edited) "Experimental" is an airworthiness category created by the FAA (CAA) that warbirds fit into (as do most homebuilts) since they were not certificated (approved) for manufacture by the Federal Aviation Administration (formerly the CAA - Civil Aviation Administration). It doesn't mean that there's anything "special" about them other than that. Edited December 7, 2019 by Juggernut nmayhew 1 Link to comment Share on other sites More sharing options...
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