|F/A 18 HORNET PART II
by Adrian WallGet ready to read the second part of this construction article on one of the best jet style models I've flown in years.
If you missed last issue, we covered just how well this bird flys (it's a real performer), as well as building the wings, both foam core and all build up. Now on with the article...
This is one part that is fairly straight forward and should not present any problems. The Hornet with its two very distinctive angled vertical fins really set this model off. It's one of the features that I believe makes this model stand out from the usual single fin type. When built to the plans they will provide a very strong model at the rear end. Hopefully you will never back this model into anything to find out.
Construction is very simple and you should first cut out the flat type framework that is needed to make up the tailplane and vertical fins. Once you have done this it's just a matter of gluing the pieces together to make the basic outline, then cover with 1.5mm balsa sheeting. The use of white glue or aliphatic glue here with the use of some weights will keep the assembly down while drying, we don't want any warps here please! Apart from cutting out the elevators and the rudders there is very little else to do at this stage. You may want to cut the hinge slots at this time while you're at it, three per elevator and at least two per rudder. The control horns, (wires that is), can also be made up at this stage, just bend to shape as per plan.
Sand the entire tail feathers to some sort of aerfoil shape. In other words round of the leading edges and tips, bevel the elevators and rudders at their front edges, the usual stuff really. Right then, what else is there? I can't really think of anything too important for the tail feathers, but just in case I've forgotten something go over the plan once more. I'm trying to do all this from memory!
Next issue we will finish off this construction article on the Hornet. In the mean time, I would suggest you get your order into Airborne’s plan service and start building. This is just such a good aircraft!
Now this is a really nice piece of work, the fuselage that is! The body, (it’s easier to type that), is not really that difficult, with a little bit of studying, the plans that is and these notes you will find that it, (the body), will come together fairly quickly.
Where do we start you say? At the beginning of course. Start with making all the formers out of ply and balsa where indicated, just like a jigsaw puzzle. Note the grain of the formers both balsa and ply.
Next you can produce the fuselage sides, all four of them actually.
The body, (there's that word again), is made up of a pair front and a rear fuselage sides, the front sides being laminated with 1.5mm ply as indicated on the plan together with lightening holes, (I wonder how heavy those holes really are). Now again with the front part of the fuselage add the triangle stock along the bottom of each side. Once you have completed this you can glue formers F1 through to F8, (please note that former F1 is glued at a slight angle for the thrust line, more on this latter), to the two front sides along with WP, the front wing mounting plate. Just make sure you keep everything nice and symmetrical. Build it over the plan if you so desire. Glue in WS1, (2 of), also the two rear wing mounts marked as WM and the undercarriage mounting blocks together with the triangle gussets. These should be glued with epoxy, can't afford to have these let go, would really spoil your day!
Let's make the rear fuselage sides. Begin by making up the two sides with the required holes cut out for the tailplane assembly, then add the triangle stock and the square balsa pieces including the parts known as TP1. Follow this up with the wing seats known as WS2, one each side.
The triangle pieces positioned at the lower edge front and rear will need to be scarfed to make them bend just a little, between F9 & 10 for the rear pieces and at F5b for the front pieces.
Now glue the two rear sides to the front sides at former location numbers F7 & 8. Double check the 'squareness' here — this will be important for an accurate finished fuselage — then add formers F6b, (2 of), F9 and F9b, (4 of). Leave out former F9a at this stage, this will be added in after the tailplane has been mounted up. Add former F5b now, (2 of).
Now with an open frame at this stage check that all the formers are secured to the sides. Once happy you can cover the fuselage assembly with the various thicknesses of balsa sheeting, just check the plan for the correct size. Leave out the 9.5mm sheeting between the fins at the back at this stage. Add the balsa block at the rear of the fuselage. Don't bother hollowing this out, you might have to add weight to the rear of the model anyway, (depending on the engine installation you use). Make up the rear radio gear access hatch and the mounting blocks required for same. Once you have completed these you can shape the tail block. Make them look like two jet exhaust pipes. Well the best you can anyway! Oh, don't forget to add the two tailpipe end pieces made from 3mm ply. There's a tail skid or arrester hook to be made up also. Fit now, or later if you cover the model in plastic type film.
Let's slip up to the other end for a change. (The fuselage that is.) The engine mount used should be one of those that are made of fibre reinforced glass, for lightness. This is one area that you want to think ‘light' where possible. The down thrust shown on the plan can be achieved by placing washers under the top bolts of the radial mounting holes, (although I feel this is not a real good idea, but it does work), or by installing some of those nifty thrust plates that are commercially available.
Fit out the engine throttle cable at this stage to suit your installation. A flexible cable here is all that is required and can be routed back to the middle of the fuse for servo connection latter.
The easiest way of doing the engine cowl, and I've mentioned this in many other articles, is to mount the engine on the mount, (you should have the mount on former F1 at this stage), and place the nose ring piece behind the spinner you intend to use together with some small spacers, say 1.5mm thick. This is to allow for the spinner to cowl clearance. Just tack glue these for now to the back of the spinner.
Now mount up the prop and spinner. I use an old prop cut down to just the hub only for this job. What you can do now is simply fill in the gap between the nose ring and the the front former F1 with the required balsa block and triangle. Don't make the fit too tight, you won't get the engine out again. Don't forget to allow for the muffler at this stage. The review model had a rear exhaust engine and looked great with the tuned pipe sitting under, (hiding), the wing leading edge extensions. This really added to the profile looks of the model in flight. Continue the balsa blocking right up to the front of the canopy come top hatch.
Good time for some sanding and shaping of the model. Go ahead and I will see you back here in a couple of weeks, (just kidding). It will be worth it in the long run.
Now you might like to beef up the nose wheel mount with some extra triangle shapes at the formers F4 & F4b. I found that the nose leg is rather long and can have a rather large lever type effect on these two formers.
The nose leg assembly is made up using two coiled noseleg units, (5/32 inch.), bound together with fuse wire and soldered. They are available from hobby shops, one being used in it's entirety and the other a cut down version. Just refer to the plans for further details. If you have good friends with suitable lathes and equipment you could always be nice to them and ask for one of those nice looking oleo type struts. Now that really finishes the model off! Although the method used on the plans is more than suitable.
A nose wheel steering block is also available and will need to be fitted in order to have the front leg steerable. Plenty of room here for this exercise and should present no problems.
The main undercarriage is bent from 3/16 inch, (4.7mm for metric men/ women), directly from the shape shown on the plans. These can be simply secured to the bottom of the fuselage using undercarriage straps. You may like to secure the straps to the bottom of the fuselage with blind nuts mounted inside the model, these are far stronger than the little screws that are supplied with the straps, also from hobby stores.
Use good quality wheels for this model. The cheap or lighter type wheels will only offer to much drag when trying to take off from a wet runway, (believe me I know).
At least when it comes to buying the wheels you won't have one left over, (two in a packet of course), this odd wheel seems to hang around for years and disappears just when you think you have a use for it!.
Okay then we can now proceed onto the canopy-hatch assembly, this will require a little extra effort here just so you can have that already nice looking Hornet really standing out from the rest of the crowd. The hatch removes completely from the model for easy access to the front radio installation and fuel tank, and of course the removal of the wing. Make up the required formers and the sides, then it's just a matter of gluing the parts together. A little shaping will be required to achieve a good result. I elected to sheet the bottom of the hatch assembly just to make it a little stronger.
This model needs a pilot, so don't build it without one. Nothing worse than watching a lovely looking model fly past with the pilot gone to sleep at the wheel, (well the stick actually) and nowhere in sight. The excuse that he dropped his pen on the floor won't work!
The rear turtle deck can be made at this stage to match the front hatch. More shaping and sanding here but worth the effort.
Now's a good time to glue in the two vertical fins. Use the template shown on the plan for an accurate alignment. Make good glue joints here. You can now fit formers F9a, (2 of), between the fins along with the 9.5mm top deck. Once you have done this glue the rear turtle deck in place onto the top deck.
With all that completed it's time to mount the wing onto the fuselage and drill the mounting holes for the wing. You can drill and tap the ply plates in the wing directly or add captive nuts underneath. Please note that the front mounting bolt will need a wedge shaped piece of hardwood underneath the head of the bolt or you could recess the bolt down into the wing. Once the wing is in place you will need to add various blocks/sheets of balsa to the top of the wing in order to line up with the rear top fuselage sheeting, (9.5m). The leading edge chines, or wing extensions, will need to be made up at this stage. This can be done as per plan or the method I used was to laminate a few pieces of balsa together and carve to shape. This section will take a little bit of work but time spent here will produce those distinctive shapes that the Hornet has. Make up the fairing, (from balsa), that needs to go onto the top of the wing at the front and leave a hole to access the front wing bolt, (this will be hidden under the hatch/canopy). A bit of sanding will be required here in order to fair in the balsa with the wing chines, (different name this time).
It's great fun producing a nice piece of work to make these fairings, until you have to do it all over again on the other side. I really hate that! So John at Airborne suggested that I produce two more, left and right of course, (just for fun), so he could have them make up a mould for making your job a little easier, enter some ready made chines, well I hope he does anyway. I would like to think that the extra carving won't go to waste John! So what else is there? The canopy which is available from Airborne can be cut to suit your nearly completed model. This is another job which I'm not crazy about but if you draw a line around the finished shape of the canopy onto the top hatch and cut a small groove along that line into the balsa you can recess the canopy. This looks quite good when filled and painted up.
By the way, I've forgotten to mention the mounting of the canopy/hatch. Simple really. Just peg the rear at F7a as shown on the plan and use a single screw at the front. You may want to strengthen up the front where the screw mounts in, wouldn't want that nice piece of work getting ejected in flight. (I can't reach the ejection handle goose, you'll have to punch us out!) Whoops, wrong type of plane!
I think I'll go off the construction for the moment so we can do something a little different, like fitting the fuel tank. This is where you will have to decide on whether to use a fuel pump in which to draw the fuel up from the tank, (assuming you mounted it where shown on the plan). After market fuel pumps are available just for this purpose, if that's not your style you could use muffler pressure and a small header tank placed just behind the engine, say 4oz, similar to what they use in the helicopter industry. Do you know why helicopters fly? They're so ugly that when they get near the ground the earth repels them! Otherwise if you use a fuel tank placed in the usual position, (directly behind the firewall), you will need to reduce it's size so as not to upset the balance of the model too much, especially when full or empty. That's enough tank talk lets get onto something else.
Nosewheel steering was achieved by using a separate servo mounted in the middle of the model opposite the throttle servo. The use of a flexible cable here will do the job nicely. Remember to use a ‘servo saver', they are also available at your favourite hobby shop.
Feel like mounting up some servos? Well, the steering servo along with the throttle servo should already be mounted, (around the middle of the aircraft), if you have been a good little modeller and followed my instructions so far. The other servos, other than what's in the wing, all go down the back of the model. A couple of servo rails will need to be made up and glued across from one side to the other just ahead of F10. They can actually be glued on top of WS2, (the tailplane seat).
Each rudder and elevator have their own servos, (nine servos used in the review model). This might seem a bit of a juggle but really is the best way to go with this type of model and you can fine tune each control position for accurate flying.
The elevator torque rods will need to be fitted to the tailplane first before lining up the elevators, (they will need to be pushed through the gap at the rear of the tailplane). The photo of the servo installation, (I hope there is one for you), is worth a thousand words, just look and all will be revealed. The rudder horns are shown on the plans both side and top views, easy to make and can be fitted with aileron type connectors to them.
With this type of installation short and quite strong pushrods can be used for all the major controls. I used 4.40 type rods for the elevators together with swivel or ball like connectors. This makes for a slop free system. Smaller rods can be used on the rudders.
The switch and charging jack where placed under the tailplane on the left side, (away from the exhaust), with the battery pack placed under the tailplane, (inside this time mate), and the receiver placed beside it made up the correct balance needed for the C of G. The receiver wire was run in a plastic tube inside the fuselage toward the front.
I'm fast running out of things to tell you, so if you can't think of anything that I may have missed then I'll mention the finish of the review model.
The colour scheme was modelled after the American Blue Angels of which there are plenty of photos available for scale detail. I was lucky enough to have another friend, (not what you know but who you know), make up some very smart looking decals and when applied to the model, looks just fantastic.
The preparation for finish was achieved by sanding the entire airframe down with medium then fine sandpaper, followed by a couple of coats of dope, (make sure that the dope cannot reach the foam, otherwise you may end up with a weak structure in some places, assuming you built foam wings of course), followed by some more sanding with fine sandpaper.
Once this step was done the model was then covered with lightweight tissue paper applied with even more dope, (better buy your dope in 44 gallon drums!!). This may seem like a lot of work, but with what you have done so far this is just what is needed to make this model look outstanding. You could cover it in your favourite plastic covering with all the trimmings but there would be a lot of work with that method also. Not your average box trainer this one! Oh, by the way, please disregard the above method of tissue covering for the wings if you built them like a skeleton. Open structure that is.
With the tissue covering exercise over with you will need to spray a light coat of undercoat over the entire mode. This will sure show up all those little imperfections. Fill the nasty looking dings with a lightweight filler, sand, and then spray with some more undercoat to check the finished results. You can probably tell by now that if you take your time with this step the overall finish of the model will do you proud.
The review model was sprayed with ‘Taubman's Fiddly Bits' paint straight from a pressure pack can, dark blue, and did the job quite nicely with the yellow trim being sprayed on after a few days drying time had elapsed. Careful masking around the canopy area will be needed for the yellow trim. Take your time here and use good quality masking tape. The use of photos for this purpose will enhance the accuracy for that final great look. A fair bit of the canopy will need to be painted also to achieve the rather small looking overall shape of the canopy if you paint the model in the Blue Angel's colour scheme.
Well, this article is getting rather long winded and will probably be edited anyway, so if you only read about a dozen lines then you will know that the ‘Ed' has used his electronic rubber. I hope you have enjoyed this construction article, even if only to learn something of construction for latter use. It's time to sign off for now, there is another rather large building project I must get on with, this one being a ‘sister ship' to the model just reviewed. So hurry up and complete this model so that when you read about the next one in the series you will clean off the modelling bench in a desperate hurry just to see how this one will fly. And believe, me this next model will knock the socks of anything you might have ever have seen before!
There, got you curious. You'll just have to wait.... but it'll be worth it!
The following points of interest might be helpful with this model, (F/A-18):
- This model is aimed at the modeller with intermediate building skills
- Think light when building at the front, (except the engine firewall)
- Build the flaps, even if you don't have that extra channel. Fix them in the up position. You never know when you might replace your radio set.
- Even though this model will fly rather slow with the flaps out, just remember that there is a lot of heavy metal way out front and this will have a slight pendulum effect on the model.
- Dual rates for the main controls are a definite advantage especially with the elevators.
Well, I'm out of here for now.
F/A-18 Fornet plans are available from:
To order a plan via e-mail
Airborne Plans Service
P.O. Box 30 Tullamarine Vic., 3043
Cost: $58.00 plus $3.00 postage
Credit Card Orders: Phone: (03) 9333 5100
Fax: (03) 9333 5099