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NOTE: Each of the pictures on this page is a clickable thumbnail which will open up to a much larger image for detailed viewing. In some cases you will notice differences between the photos and your plans and parts. This is due to changes made during the building of the prototype. I've tried to make note of the changes but if I missed anything please assume that the plans are correct.

Fuselage Construction

Image 1

Image 1

1. Begin by marking a line that is 1.75 inches back from, and parallel to, the front edge of both F1 parts. This is simply a reference line to help maintain alignment when installing former F4 later. Mark them on the outside and be sure to make a right and a left. (Image 1)

Image 2

Image 2




2. Assemble the servo tray from F3, F3a (x2), F16 (x2), and two 1 1/4" lengths of 1/8" x 1/4" plywood as shown in Image 2. An isometric detail drawing can also be found on Sheet 1 of the plans.





TECH NOTICE 3-31-2011: An error was discovered in the isometric drawing of the servo tray on Sheet 1 of the plans. The two F3a braces should be glued to the bottom of the tray rather than the top as the drawing shows. In other words, the two F3a parts should be on the same side of F3 as the two F16 parts. The plans have been corrected but if you're kit was purchased prior to 3/31/2011 then your drawing is incorrect. The corrected drawing can be seen here.

Image 3

Image 3


ATTENTION: DO NOT GLUE THE SERVO TRAY IN PLACE IN STEP 3 IF YOU PLAN TO INSTALL THE FULL COCKPIT KIT.

3. Dry assemble (no glue) the basic fuselage box structure consisting of the two F1 sides, the F2 tank floor, & the servo tray assembly from step 2. It may be necessary to tape the servo tray in place temporarily. Lay the assembly on its side and glue F2 in place being sure that it is square to F1. (1-2-3 blocks are being used to keep the assembly square here) Once dry, add a piece of 1/2" balsa tri-stock to strengthen the joint. Notice that the tri-stock needs to be held back from the front edge by 1/4" to allow for installation of the firewall later. Flip the assembly over and repeat for the other side. Be sure that the servo tray stays accurately in position to help keep the structure square. Also be certain that the lines you marked on the F1 parts are to the outside. (Image 3) Glue the servo tray assembly in place at this time ONLY if you do NOT plan to install the full cockpit kit. Otherwise simply leave it dry fitted (or taped) in place for now.

Image 4

Image 4



4. Slide former F4 into position starting at the rear of the F1 sides and carefully moving it forward. It may be necessary to sand the inside cut out of F4 to allow it to slide into position. It should be snug but not too snug! Use your marks from step 1 as a reference for accurately positioning F4 and then glue it into place. (Image 4).



Image 5

Image 5




5. Fit the tabs at the rear of the F1 sides into their respective slots in former F9. Stand the assembly vertical with F9 flat on the bench. Make certain the two F1 sides are square to the bench and then glue F9 in place. (Image 5) NOTE: Make sure the center line mark etched into F9 faces towards the front of the fuselage.

Image 6

Image 6




6. Add some 1/4" balsa tri-stock to the corners of F1 / F9 to strengthen the joint per Image 6.



7. Laminate the two 1/8" Birch plywood FW firewalls together with epoxy being carefull to get them accurately aligned.

Image 7

Image 7


8. Dry fit the firewall (FW) from the previous step onto the main fuselage box and sand as necessary to get a tight, gap free fit. Once you are satisfied that it is correct use epoxy to secure it in place. Next, add formers F5, F6, F6a, F7, F8, and F8a to the fuselage box per Image 7. Please take note that both F6a & F8a have a slight negative V-shape to one side which needs to face down. See Sheet 1 of the plans for a section drawing through F6 for clarification. It may be necessary to open up the various slots in order to allow the parts to slide into place without having to apply too much force. Once again, a snug fit is desired but not so tight as to threaten breaking the parts while fitting them together. Pay particular attention to the tab on the top of F5 which fits into the corresponding slot in the F2 tank floor.

Image 8

Image 8




9. While it is still easy to access go ahead and add some additional 1/2" balsa tri-stock in the corners of F1, F2, and the firewall as seen in Image 8.

Image 9

Image 9





10. Construct the two main fuselage longerons from parts C1 and a length of 1/4" x 1/4" hard balsa strip stock per Image 9. Cut the strip stock 34.625" long (34 & 5/8") or use the top view on Sheet 1 of the plans to determine the exact length. NOTE: If you plan to use something larger than a .90 for power, or if you will be using a gas engine, it is recommended that 1/4" square Spruce or Basswood be substituted for the balsa strip stock.



NOTE TO BUILDER: The next order of business is to make up the jigs for assembling the remainder of the fuse. The Hellcat is built using the elevated crutch method which simply means the two main longerons which form the crutch of the fuselage are suspended high enough to hold the lower fuse clear of the building surface. To achieve this I cut jigs from 1/2" or 3/4" thick Medium Density Fibreboard (MDF) which are approximately 5 inches tall. The need to be at least 4 1/2" tall but the exact height is not important AS LONG AS THEY ARE ALL THE SAME. The material used to make them is not critical either, whatever will get the job done. You will need 3 of them that are at least 5 inches wide and 2-4 more which can be narrower. These jigs are tack glued directly to the building board in strategic locations to support the longerons while the remainder of the fuselage is constructed. This will all be explained in more detail below but the first step is to acquire the necessary material and get the jigs made. NOTE: A glass building surface is ideal for this as the jigs can be tacked directly to it and then removed later without damaging the glass. If glass is not an option then MDF will also work very nicely. I have had no issues with the MDF being warped but double check it just to be certain that it is flat and true.

Image 10

Image 10




11. Mark a vertical center line on each of your 5 inch wide jigs. Tape the top view of the fuselage down to your building surface. Tack glue the first jig in place on top of the plan flush with the back side of F9 being careful to line up the center line of the fuselage drawing with the center line on your jig. It is also necessary to ensure that the jig is vertical to the building surface so a couple of squares or 90 degree triangles will be most helpfull here. I cut small squares out of the plan where the jigs are tack glued so that I am gluing to the table on not just to the paper. (Image 10)

Image 11

Image 11





12. Dry fit the fuselage longerons into place on the fuselage box structure, do not glue at this time. Roughly position two more jigs at the front of the longerons underneath C1 but do not tack glue them down yet. This is where you will want to use a couple of the narrow jigs if you made some. I used wide ones simply because it was all I had on hand. Position the fuselage on top of the jigs per Image 11.

Image 12

Image 12




13. Line up the center line on F9 with the center line of the jig and clamp in position. (Image 12) It is best when trying to match up the center lines if you sight straight down from above. (Mine are lined up despite the fact that they don't appear to be in the picture!) Be sure the 1/4" square longerons are down tight against the jig before clamping F9.

Image 13

Image 13





14. Line up the center line etched on the firewall (FW) with the center line of the fuselage top view and then situate the two forward jigs so that they are back against F4 and tight against the sides (F1) of the fuselage box. Once you are satisfied that everything is lined up properly tack glue the jigs in place. (Image 13)

Image 14

Image 12




15. Install another jig at the rear of former F10 in the same manner as that of F9. It my be helpfull to dry fit the F14 fuselage spine in place to help with alignment. Once again be sure that the center lines are matched up and the longerons are down tight against the jigs before clamping F10. (Image 14)

Image 15

Image 15





16. Move towards the back of the fuselage and install another jig to support former F12 per Image 15.

Image 16

Image 16




17. Transfer the location of former F11 from the plan to the fuselage longerons using a square or similar. Slip F11 into place and then double check to be sure it is perfectly vertical. (Image 16)






18. Once you are satisfied that F10, F11, and F12 are accurately positioned tack glue them in place on the longerons. Go ahead and permanently install F14 at this time as well. It is recommended that you lightly tack glue the joints now and then remove the fuselage from the jigs for final gluing so as not to stick the fuse and jigs together!

Image 17

Image 17




19. Move to the front of the fuselage and install the 1/4" square balsa top stringer as well as the two short stringers that define the cockpit opening. (Image 17)

Image 18

Image 18





20. Assemble C2 together with F13 and F13a. C2 is the aft end of the crutch and is made from 1/4" balsa. It plugs into a receptacle in former F13. F13a sits on top of C2 and is centered on the front face of F13 per Image 18.

Image 19

Image 19




21. Install the C2/F13 assembly on the longerons per Image 19. Take your time and make sure everything is straight and true before gluing. It may be helpful to use another jig to hold the assembly accurately in position.

Image 20

Image 20




22. Next add the F17 stab seat doublers. Be cautious to get these down tight to the tops of the longerons in order to maintain accurate incidence of the stab. I glued these to F13a first, then pulled them into position and glued them to F12. Lastly they were glued to the longerons. NOTE: Due to a miscalculation on my part F17 was found to be about 3/32" short at the front, bottom corner. This is not of any real concern and the parts can be used as-is without issue. However, the perfectionists out there may want to add a bit of material to correct for my error. For those who received kits after March of 2011 this error has been corrected in the kit. (Image 20)






NOTE TO BUILDER: Steps 23 and 24 cover the installation of the servo tray ONLY for those who will be adding the full cockpit kit. If you do not plan for a full cockpit then you should have already installed the servo tray and you can skip directly to Step 25 at this time.

Image 21

Image 21


23. Find the two 1/8" light ply parts FC1 which should have come with your cockpit kit. Install these onto the servo tray, as well as some scrap plywood to back up the servo mounts, as shown in Image 21.



Image 22

Image 22





24. Install the servo tray just aft of former F8 with FC1 sitting directly on top of the F1 fuselage box sides. Scrap balsa doublers are added to strengthen the joint. (Image 22)








Image 23

Image 23




25. Block sand the top of F14 and the formers and then add the 1/8" balsa F18 to the spine of the fuselage and sand it to shape per Image 23.

Image 24

Image 24





26. Temporarily remove the fuselage from the jig. Add a 1/4" x 1/8" SOFT balsa strip to the outside of both longerons. This strip fits into the notch in C2 and should extend forward to be flush with the front of former F4. The purpose of this strip is to allow you to use very soft balsa which can be easily sanded to match the contours of the fuselage formers. Sand the excess off of C2 as well until it blends seamlessy with the F17 stab saddles. While your at it take the time to taper former F13 as well. Time spent here to sand accurately will prevent any bulges and/or flat spots when you sheet the fuselage. Lastly, open up the hole in F13a where the elevator push-rod will pass through. (Image 24)

Image 25

Image 25




27. Align and clamp the fuselage back in the jig and tack glue some 1/8" balsa scraps to the tops of the jigs on either side of the longerons. These must be made from 1/8" thick material and their purpose will be explained below as we begin to sheet the fuselage. (Image 25)




TECH NOTICE 4-18-2011: Before proceeding you need to decide if you will be sheeting with 1/16" or 3/32" balsa. The plans show 3/32" but it is my opinion that medium weight 1/16" is more than adequate for sheeting the Hellcat. If you do choose to stick with the 3/32" then please do your best to source some light weight material for the task.

ADDENDUM 1/30/2012 - Having now completed my second fuselage, this time using 1/16" sheeting, I would like to share my findings. The 1/16" is certainly more than adequate strength wise for the task. I used 1/16" inch everywhere with the exception of the area forward of the cockpit which was planked with 3/32" as shown in the construction gallery. The bottom rear fuselage was sheeted with 1/16" which worked well but the thinner material does sag just slightly between the formers resulting in a slight "starved horse" look. It is minimal and well within acceptable limits for my standards but for those who wish to avoid it completely a return to 3/32" sheeting is recommended.

Image 26

Image 26



28. The majority of the top half of the fuselage is sheeted in two halves. Start by making up the two sheets which fit as shown in Image 26. Note that the sheet splits the fuselage longerons in half, leaving the lower half exposed to allow for the bottom sheeting to be attached later. It is recommended that a template be made from light cardboard or similar to ensure a good fit before making up the balsa sheets. I can provide a PDF file of the template to save you some time, just send me an email with your request. The sheets need to fit accurately down the center of the longerons and flush with the tops of the 1/4" square cockpit stringers but can be left slightly large everywhere else and trimmed off after attaching.

Image 27

Image 27




29. Next step is to go ahead and attach the sheeting to the fuse. (Image 27) I started by attaching the sheeting to the longerons first then slowly working from the center out as the sheeting will need to stretch some around the compound shape of the fuse. I tack glued everywhere that I could with the fuse in the jig. Once the majority of the sheeting was tack glued the fuse was rigid enough to be removed from the jig and the remainder of the sheeting glued from the inside. Work slowly and plan ahead is the best advice I can offer here. When finished trim and/or sand off any excess sheeting.





NOTE TO BUILDER: Despite my best efforts I still ended up with an unwanted bulge in the sheeting forward of the cockpit. I did not have this issue with the 3/32" balsa sheeting on the prototype fuselage but the fuse seen here is sheeted with 1/16" and this may be the cause. At any rate, it's an easy fix so don't fret if your fuselage exhibits the same issue. You can see the problem area in Image 28. If this is not a problem on your fuse then you can skip Step 31 if you so choose.

Image 28

Image 28






Image 29

Image 29






30. Add some 1/4" wide strips of 1/16" or 3/32" balsa to the underside of the sheeting between formers F4 & F6 and also F6 & F7 as seen in Image 29. Leave half the width (1/8") exposed as a shelf for attaching the planking that will complete the nose.

Image 30

Image 30



31. Plank the remaining area forward of the cockpit with light 3/32" balsa. I do not enjoy planking and so spend as little time as possible doing it! I was able to get away with four pieces here but a couple more probably would have been better. (Image 30) Alot depends on the density of the balsa being used. Very light wood will allow you to get away with fewer planks. I have provided a few tips for planking on the Tips & Tricks page for those interested. I will reiterate that probably the most important advice I can give regarding planking is NOT to use instant glues for the job! Carpenter's wood glue or something similar is a much better option.

Image 31

Image 31



32. Image 31 shows the planked area after a thorough sanding. Sanding is one of those tasks that seems pretty straightforward at first but actually contains a considerable amount of nuance when done really well. It's also pretty difficult to explain the nuances! My best advice is to sight down the area being sanded often, in good light, and from various angles to look for high and/or low spots that may spoil the smooth shape. Once again, work slowly and methodically. I use a relatively rough block, 100 grit or so, and sand ACROSS the grain to knock the planking down to the basic shape. Then I switch to a finer grit block, sanding primarily with the grain and then finish up by hand sanding with some 220-320 grit paper. When hand sanding I tend to work the paper in relatively small circles to blend everything together.



NOTE TO BUILDER: At this point the fuselage is rigid enough that work can continue without the aid of the jigs and the they can be discarded.

Image 32

Image 32



31. Install the two F5a doublers on the back side of F5 per Image 32.

Image 33

Image 33






32. Bevel the top edge of F9a and dry fit (no glue) the two F9b parts as shown in Image 33. The top of F9b is marked to allow proper orientation as it is not symmetrical. Test fit the assembly in place on the fuselage to make sure you have sufficient bevel to allow proper fitting of the mating parts. It may be helpfull to sand a bit of bevel on the tabs of F9b so that they easily slip into the slots in former F9.

Image 34

Image 34



33. Once you are satisfied with the fit of F9a/F9b to the fuselage go ahead and glue it all in place. (Image 34)

Image 35

Image 35






34. Add the 1/4" square bottom stringer per Image 35. Take care to ensure all the formers are nice and straight before gluing.

Image 36

Image 36






35. Add the four 3/16" square bottom stringers as shown.(Image 36)

Image 37

Image 37






36. Epoxy the 1" x 3/8" wing mounting block in place per Image 37 along with the doublers marked "G". Each "G" is made up of two 1/8" light plywood laminations and these are provided in the kit.

Image 38

Image 38






37. Add the 1/8" balsa F21 wing saddle doublers per Image 38 and Sheet 1 of the plans.

Image 39

Image 39






38. Back up the 1/2" diameter holes in formers F5 and F9a with some light plywood disks per Image 39. Several 1" diameter disks are provided with the laser cut parts for this task. These receptacles are for the 1/2" diameter rare earth magnets that are used to attach the belly pan. If you intend to use this method you will need to source the necessary magnets. I found mine on ebay for a bargain price. They MUST be rare earth type magnets to do the job and you will need four total. (You may have to purchase more but they are inexpensive and come in very handy.) Having used this method on the prototype I can recommend it without hesitation as being more than adequate to keep the belly plan securely in place for flight.

Image 40

Image 40






39. Assemble the tailwheel mounting bulkhead from parts F19 (x2) and F20 if you will be using the Robart retractable tailwheel unit, or alternatively from F19a and F20a if you will using the fixed tailwheel. The photos here show the retract but the fixed installation is similar. It is recommended that assembly be done with epoxy and also that balsa tri-stock be added to the inside corners for extra strength. (Image 40)

Image 41

Image 41






40. Mount the tailwheel unit to the F20 bulkhead with wood screws as shown in Image 41. Remove the retract unit and soak the threads in the bulkhead with thin CA glue and then reinstall the tailwheel.

Image 42

Image 42






41. Carefully cut or file a slot in the top of F20 as shown in Image 42 in order to allow for the full range of movement for the Robart retract unit.

Image 43

Image 43






42. Install the tailwheel mounting assembly on former F12 as shown in Image 43. It may be necessary to sand the tabs on parts F19 a bit in order to allow them to slip into the slots in F12 without excessive pressure. Be sure the balsa tri-stock added to the inside of the bulkhead assembly does not interfere with its installation as well. Once again it is recommended that epoxy be used and that balsa tri-stock be added as shown to strengthen the joints.


NOTE TO BUILDER: Before proceeding to sheet the remainder of the fuselage it is necessary to install the control runs for the rudder, tail wheel steering, and tail wheel retract actuation while we can still access the inside of the fuselage. As designed the Hellcat uses pull-pull actuation for the rudder and steering for both the fixed and retract tail wheel options. This is certainly not necessary however and you may choose tube-in-tube or push rods if you so desire. For the benefit of the less experienced I show my set up in the steps below. For those that have their own methods, carry on!

Image 44

Image 44





43. Install your chosen servos into the servo tray as shown in Image 44. The center servo is for rudder/tail wheel steering while those on either side are for elevator and tail wheel retraction. On my airplane the servo to the right in the picture is for elevator actuation but it could just as easily have gone to the left, makes no difference. Please note that the servo tray in the picture is in the aft position as this model will be getting the full cockpit. The servo lay out is the same in any case. Also be aware that this picture was taken after I had installed the control runs but they should not yet be there on your airplane!

Image 45

Image 45






44. Cut a 3/16" wide by 1/2" long slot at the location indicated in Image 45 on both sides of the aft fuselage in preparation for installing the sleeves which will carry the rudder pull-pull cables. Use a round file or sandpaper wrapped dowel to elongate the openings until the sleeve can smoothly pass through at the necessary angle without bending.

Image 46

Image 46






45. Insert the sleeves through the slots created in the last step and route them to the rudder servo with as few bends as possible. I made anchors from scrap balsa to lock the sleeve in position at each bulkhead as shown in Image 46. The length of these are adjusted as necessary to hold the sleeve exactly where you want it. Please note that my airplane is set up so the rudder pull-pull hooks up to the third hole out on the servo arm and the tail wheel steering will be on the outermost hole as I want to achieve maximum throw for steering on the ground.

Image 47

Image 47






46. Securely glue the sleeves to the inside of the sheeting where they exit the fuselage (I used epoxy mixed with microballoons) and then trim the sleeves flush with the sheeting. (Image 47)

Image 48

Image 48






47. The sleeves for the tail wheel steering are installed in exactly the same manner as the rudder sleeves. The yellow inner nyrod was used as sleeving for the tail wheel steering on my build. The routing for these will require a gentle "S-curve" in order to go from the servo to the steering arm on the tail wheel retract unit. When drilling the holes in bulkhead F12 take care to align them so that the sleeves provides a direct shot to the steering arm as seen in Image 48. Steering for the fixed tail wheel is achieved in the identical manner.

Image 49

Image 49






48. Finally we install the linkage to actuate the tail wheel retract unit. I used tube-in-tube for this in order to easily route it around the bulkheads as necessary. However, a solid push rod such as an arrow shaft can be made to work if you prefer. It is recommended that you go ahead and get this linkage hooked up and operating now as it can be difficult to access the connection at the retract end once the horizontal stab is in place. (Not impossible but difficult!) Image 49 gives a detailed look at the connection to the retract unit.

Image 50

Image 50






49. Image 50 gives an overall view of how the various control runs are routed through the aft fuselage. The elevator will be actuated via a carbon fiber arrow shaft that will be installed later in construction.




NOTE TO BUILDER: We will now return to sheeting the fuselage. Due to the dramatic shape change between formers F12 and F13 it seemed like it might make things a bit simpler to sheet that small section beneath the stab seperately from the remainder of the fuselage. This is not absolutely necessary and I leave it to your discretion. You may choose to sheet it along with the lower sides in Step 51 in which case you can ignore steps 50 and 54.

Image 51

Image 51






50. Use a scrap piece of 1/8" or 3/32" balsa to create a doubler for the back side of former F12 which fits between the crutch and the aft stringer as shown in Image 51. Do this for both sides.

Image 52

Image 52






51. Add the lower section of sheeting outlined in red in Image 52 to both sides of the fuselage. Be sure to sheet only to the center of the lower stringer so you have something to attach the neighboring section of sheeting to.

Image 53

Image 53






52. Next I sheeted the center bottom of the fuselage as shown in Image 53. Once again be sure to leave the upper halves of the stringers exposed to carry the remainder of the sheeting.

Image 54

Image 54






53. Cut, fit, and install the remaining two large sections of the bottom fuselage sheeting. (Image 54)

Image 55

Image 55






54. Fit the two small sections of sheeting underneath the horizontal stab between F12 and F13. It may help to wet these in order to easily achieve the necessary curve. (Image 55)




NOTE TO BUILDER: The last bit of fuselage to be sheeted is the narrow section between the leading edge of the wing and the back of the cowl. Please consider now whether you plan to install the lower exhaust outlets. While these do contribute minimally to getting hot exhaust out of the cowl they are primarily for scale appearance and are not absolutely necessary. On my model I opted to route my engine exhaust out of these areas to prevent any non-scale exhaust openings from being necessary. If you do not intend to install them then you may ommit the installation of the 1/2" balsa blocks and simply sheet the entire area.

Image 56

Image 56






55. Remove the sections of formers F4 & F5 as shown in Image 56 to make way for the exhaust outlets. These are laser cut and you need only to cut through the small tabs to complete their removal.

Image 57

Image 57






56. Cut and fit two 1/2" thick balsa blocks into the notches created in the previous step. (Image 57)

Image 58

Image 58






57. Add the remaining fuselage sheeting around the 1/2" blocks as shown in Image 58.

Image 59

Image 59






58. Sand the balsa blocks and sheeting flush with formers F4 & F5 and then carefully sand the blocks to match the contour of the sheeting. (Image 59)

Image 60

Image 60






59. The spine of the fuselage is capped with soft 3/8" balsa sheet. Make the cap slightly large all around as seen in Image 60. Please do yourself a favor and source the lightest balsa you can find for this purpose. If suitable 3/8" is not readily available then the spine can be laminated from multiple sheets to get the desired thickness. If laminating take great care to glue only near the center of the laminations so that you do not end up sanding into a glue joint which makes achieving a smooth contour almost impossible. It is recommended that each lamination be applied individually to the fuselage and rough shaped prior to adding the next lamination to reduce the chance of getting glue where it is not wanted.

Image 61

Image 61






60. Rough in the shape of the spine to match the fuselage sides per Image 61. A razor plane is a nice tool to have for this job but a 60 or 80 grit sanding block will make quick work of the job as well assuming soft balsa was used. Sand across the grain to remove material quickly and then sand with the grain to draw down to the final shape. Be carefull not to sand too much on the fuselage sheeting but rather concentrate the pressure of the sanding block on the spine itself. Work slowly and sight down the fuselage often in good light to check your progress. It is better to work slowly and get it right the first time then to have to try and add material back where you were a bit overzealous!

Image 62

Image 62






61. Finish shaping the spine using a 120-150 grit block to start with and then moving to some 220-320 grit cupped in your palm to conform to the top radius. Once again it is recommended that you work slowly and check progress regularly by sighting down the fuselage from various angles in strong light. There is a lot of nuance to the art of sanding but I don't know any way to learn it other than by doing it. Generally I find that when I think I'm getting pretty close to done I'm usually about two-thirds of the way there! Time spent here will pay dividends in the final look of the model so don't rush it. Take note that the spine gently flattens a little bit where it matches up to the rear edge of the canopy. Use the side view drawing of the fuselage on Sheet 1 of the plans as a guide. (Image 61).