Build your first flying scale Jet - Chapter 1 - Getting started

For this model I decided to show a different, and less smelly, method of transfering the parts patterns to the balsa.



I covered balsa selection in the Comper Swift article, so I will not repeat myself here. However, I would just emphasise again that it is important to watch the weight with a model like this, and I think it is worth the extra cost seeking out and buying some decent quality lightweight balsa. Compared to the hours you will be investing in this model, it is a small price to pay. This time I used a pack of selected 1/16” x 3” sheet from SAMS Models. More details and prices can be found on their wood page here.



The 3 inch wide parts sheets were cut out of the paper, and placed face down on a scrap sheet of paper before rubbing over the back with a restickable glue stick (after all, you do not want to make your cutting mat sticky). These repositionable glue sticks are not easy to find in the UK, but one source is Blots pen and ink supplies who do a mail order service.



The paper is then stuck directly to the balsa sheet, and placed under a book for an hour or so to keep it flat (there is a slight tendency for the sheet to curl).



You end up with a collection of part sheets ready to cut out.



Here you can see several fuselage formers have been cut out with my trusty Swann Morton scalpel. I store the parts in a zip lock bag after cutting them out to stop me losing them.



Compared to bare printed wood, I find that cutting through the paper and wood at the same time does blunt the scalpel quicker, and if the edge does start to go, you are more likely to crush soft balsa under the paper. I found I had to change the blade after cutting out a single sheet of parts. On the plus side, the paper does a good job of stopping any splitting when you are cutting across the grain. A couple of evenings cutting out yielded the following collection of parts It is best to leave the paper on until it is time to use them. You will find the paper peels off easily without leaving any residue behind, just like a post-it note in fact.



The first assembly job is to glue the front and rear side keels together. Tape the two halves of plan sheet 2 together, lining them up using the "join here" markings (cut one sheet through the marks, then line it up with the other sheet). The plan sheet is placed on the building board and covered with plastic film to protect it. The keels are placed over the plan and held in position with pins.



Do not push the pins through the wood, but rather either side of it. I used aliphatic wood glue to join the front and rear sections. Eagle eyed readers will see I have invested in some new pins since building the Comper Swift. These purpose-made modelling pins came from Flitehook, and are thinner than most standard dressmakers pins. This means less risk of splitting if you push them through a piece of balsa wood.



Unlike the box fuselage of the Comper Swift, The Thunderstreak uses half formers and keels, and a completely different building method, so I will go through the process in some detail.

Join the two halves of plan sheet 1 together and place on your building board, covering with clear plastic film again. The various vertical keel pieces are now pinned in place over the plan, gluing together where necessary.



This is just a closer view of how the keels are pinned down.



It does not really matter where you begin, but take one of the half formers and glue it to the keel pieces as shown. You want it to be vertical, at 90 degrees to the building board, so some sort of support or guide is useful. I use cardboard “set squares” with a 90 degree angle which can be pinned to the board as shown. The pliers are just holding the former down while the glue dries



When this is set, you can add the next former, and work out towards the front and rear of the fuselage. To stop a former pulling over slightly as the glue dries I sometimes place an object (e.g. this scalpel) on top for a few minutes to hold it steady.



Here the front former is being held at 90 degrees.



And here the final one at the rear.



The next step is to fit the side keel, which stabilises the whole structure. I found I had to adjust the position of the slot upwards slightly in F10 to avoid a kink when viewing along the fuselage (see photo below). It should run dead straight. Apply a small spot of glue to each slot and use a pin to spread it into the recesses. After fitting the keel, check the formers for their angle to the building board, and while the glue is still wet adjust any that look to be leaning over.







After everything has set, the fuselage half can be removed from the board.



The next stage is to glue the other halves of the formers into place, and here it is simplest just to use Mk.1 eyeball to line them up correctly. This is what it should look like before the second side keel is added.



When the keel is glued into place, check along the fuselage that it looks straight and that the formers look correctly aligned when viewed from above.

Before adding stringers, now is a good time to add the 1/16” square braces across formers 5,6 and 7, between the side keels. These are not essential, but I think they provide useful bracing between the wings in case of a wingtip landing. You can see them on the photo above.



We also need to add the spacing piece between keels 4 and 5, which sits in front of the motor (this could have been added on the building board of course)

It is now time to start adding a few 1/16” square stringers one at a time, alternating between sides so as not to bow the fuselage. No photo of this step I'm afraid, but I added the stringers next to the side keels first, one above, one below. I used 1/16” square “super strips” from SAMS models for these, rather than stripping my own. I like using good old fashioned balsa cement for gluing stringers in, as it sets up fast, and you only have to hold a stringer in a slot for a minute or so before it grabs. Be prepared to open up stringer slots if any of the runs look wobbly.



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