So when a plan has a detail on it such as a hatch or in my case lovers how do you find out what the right size of the detail is? In this case the louvers are not showing on the plans but I know they belong there on the full scale plane. Any help would be greatly appreciated.

Dan, you need to find out what scale your plan or picture is etc. You can also use proportions. So if your plan for your plane is full size and you have a 3 view that is smaller. Find and measure an identifiable part on both. I use metric mm. Much easier to do the math.

Divide full size plan part by smaller scale part. That number is the ratio or proportion between the two sources. Now you can measure any part on the smaller view or picture and multiply by that ratio to get the size part you want on the full size plan.

You can do the same with a photo too if you know the full scale size on the aircraft. Like a wheel diameter etc. do the same thing and now you have a close approximation of the part size from the photo.

Here is my latest scale up results . I’m working on a P 51-H model there is little info on this hot rod “ super prop” plane as only a few were made and they never saw combat. Only 5 are still in existence 2 flyable 2 display and one in restoration . All are too far away to visit. There are only a couple plans available both too smal for giant scale 1/5 or larger. Soni purchased a set of plans with the idea of up dating and “ scaling up. I’m sure there are plenty of us that had advanced drafting in schools so I’m not getting into that that. There are national archives that we can get into sonic signed into at least two of them these provide exact North American origins drawings which will help in creating at least scale outlines. I’ll know today how the blow up of the plans goes. Here is what I expect. Sconce the scale factor difference is about 43% the result will be poster or demonstration size paper. What I’ll have to do is cut this up and lay it out as some thing about the same as Ziroli construction which I like having built a number of his planes. In other words I’ll cut out say a wing section and lay bit in a page of my own kinda like a ziroli D model then do the same with the fuselage. Of course all related parts will have to be cut out too. Then this new drawing will get copied soni have a building plan set . Sounds complicated . Yes it is . But the plan set is not on cad so it’s a hand process. I worked in the microfilm and cad print room so this was done when machines were wanted enlarged rather than re “ draft” the drawings . I’ll then cut a kit if parts in wood and required materials . Then we start the actual build process. That in itself can take a while especially in my advanced age and health. Fortunately my son has picked up the hobby big time and is a very good builder . I can’t estimate the time frame but I’ll post as it goes . As you all know by now Robart has shut down retracts so that leaves Sierra we have one set of his retracts now and will probably get another as we will have at least three P 51 planes shortly. There won’t be any Fiberglas parts available so I’ll have to fabric at everything . I’m trying for ss good of scale outline as possible wing span is the same as B and D modeled the rudder is the major change as the H model was 600 pounds lighter and had smaller fuselage fuel tank this was the attempt to correct stability problems. Well documented . Anyway this will be one of the first things corrected . Wing shape is slightly different but the new plans will reflect this . The chin scoop and belly scoops were changed but I have info on them. This will be a stinZgR MEGA POWER. Belt drive electric power we already have this and it’s incredibly powerfull .

So this is it for to day .