Building the Fuse

Heres a shot of my fuse outline. I am doing this in the 3D program Solidworks. I decided to do this shot because it has all the fuse dimensions on it. I always seem to get questions about size, so I have decided as I post from solidworks, that I will first show the dimensions to give everyone a better feel for the size.



Here I took some formers and placed them in proper locations. I also extruded a framing tube and put that in place. This wont be the final version I use I am just using some part files I had from the drawings I have for this done by David Johnson. But this will show you the difference after I get them all going.


Now I decided as I draw up these plans to show step by step how I do it as there are a lot of people curious how to design their own set of plans.

The first thing I want to do is look at the shape of the fuse. The overall shape seems to be oval. here is where you need to look at pictures of the aircraft you are modelling and any 3 views. Any decent set of 3 views will show a few cross sections of the fuse. In the case of the Pfalz it has a slight strightness to the side of it similar to a Albatross DII rather than the oval shape of the Albatross DV. The second thing to look for is changes in the shape of the fuse. For example does it go from round to square? (yes some do like the Salmson and others) or does it go from pure circular shape to oval? these are questions you have to as yourself and look for.

From all I have been able to see on the Pfalz it uses the same shape for the entire fuse. This makes life easier. First thing you need to do is trace or draw up just 1 former. pic a former somewhere in the middle of the plane as it is easier to trace and will also give you usually the maximum outline deviation. Example being if the oval shapoe has flat spot on the side as in the Pfalz. This usually means the longest stretch of flat will be in the middle or wherever the largest former will be.





Heres a shot of my fuse former outline. This is from the center of the plane and I will resize it for every station along the fuse. These will be my guides for lofting the fuse shape.






Next I use the dimensions from the first picture to set up planes in Solidworks where I will place the fuse formers to help with lofting. I still have to do a fuse side view and top view to help with the lofting process and hope to have that done tonight or tomorrow.




Heres a shot of my fuse outline. As you can see the front of the framing stops where the vertical light blue line is. You can also see the cutout and the engine hood. What I will do first is to continue the top of the fuse in a straight line as the rest of the top fuse is. The portion between the vertical blue line and the Vertical orange Line is where the radiator and engine cowl go, so I will ignore that area for now.



Here What I have done is continued the top of the fuse forward. you can see how the top started at the cockpit and ran straight to the engine hood. Stuff like this is where you just have to guess as to what the missing section of the fuse looks like. The reason we are concerned is because in order to do a proper loft of the fuse you need to have a definate flow for the software to follow in order to give you the best results. If I had left the cutout section there my loft would have went all goofy on me.

Second reason is because it will give you formers to use to either make a plug for a glass engine hood, or it will give you the formers so that you can build up an engine hood. I also extended the fuse drawing to the front of the engine hood so I have a front former for it.



Here I have taken the side view of the fuse and made measurements for the former height and also measurements from the top of former to the datum line so that I can adjust the height on my former and then locate the datum line properly.



In this shot I took the top view and made measurements so that I can adjust the width of my former.

You will notice I am only using half of the top view. I will also use half of the former also, so that I can just mirror the fuse half so I know its perfectly symetrical.



Here I have taken the half formers and put them on their associated planes. This is where the pain in the butt comes in. it is the hardest part of the whole design stage in solidworks. First when I placed my side and top views of my fuse I lined them up on the origin point. After I adjusted my formers and made sure I adjusted my datum line on my former outlines. I use the intersection of the vertical of the half former, and the datum line to center on the origin point. This makes sure everything is where it is supposed to be.

The next stage can drive you nuts at times. We now try to use the surface loft and loft from former to former the length of the fuse and hope everything works properly and we get a nice shape. There are often errors for the first handfuls of tries. the most common error is that your parts dont intersect each other. This usually means a measurement isnt quite correct. and it only has to be off a few thousandths to cause the error. Thats when its double check measurements and try again until you get it right.



My First attempt at the loft I only got half way down the side before it gave me an error. Also notice thers a slight indent at the bottom of the last section. this can go away if the loft continues. The indent may not go away and if that happens I will hafe to adjust the former slightly. the good thing is looking down the top and side from a slight angle and not atraight on its pretty smooth. I wont be posting a ton of pics everythime I try, but tomorrow will try it again and see if I can get the problem solved. once it lofts your worries are basically over and the rest of the design comes together quite nicely.



Ok now either I got lucky or I am just getting better at lofting fuses. My second attempt it came out perfect. I did not change anything at all, but decided to just try it without using my side view for a guide curve. I usually like to use my side view as a guide curve for these lofts as a lot of times it wont be quite correct.

However in this case as you can see from the above photo the loft matches my top view perfectly



Here you can see it also perfectly matches my side view and that little indent at the bottom that was there before on the first attempt is gone.

My Next move is to mirror the shell, knit it together, then thicken it to the thickness of my sheeting. Once that is done I will save the file 3 times. The first save will be a backup file of course. The second save I will cut out the cockpit and engine notch in the front. The third save I will cut out everything but the engine hood, and use those formers for making my engine hood either as plug for a glass hood, or as a plug for a metal hood I havent decided yet.



Heres a shot of my fuse after I cut out the cockpit and the engine bay.



This photo shows a closeup of the nose section. Remember earlier I stated you should add a small section so that it covers the engine hood, well now that we have it lofted so that we can get a former shape from it we now cut off that section of the fuse back to original position.



An we have an engine hood and I even prepainted it a sorta purple. I need to look up the RGB for the original color and edit it.



Here I made a temporary assembly to put the engine hood on top of the fuse. I am happy with the looks of this.



Heres another angle of the assembly.



After I lofted the fuse I then brought in my blank sheets of wood and using the section view traced out the fuse formers.



Next I placed the fuse skin on top of the formers. later I will hollow out the formers and make the angled formers I need in the tail section.










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