FMS F-15 hack for carrier

Whys and Wherefores  Zoe Quilter Oct 2025

Briefly this was a project driven by many factors, and also to scratch the itch of getting jet models to fly in carrier. Whilst I have enjoy flying almost any carrier model, I do crave for more scaleish and different looking models. Whilst not impossible to win a comp with one, it would be very challenging to do so. 

Inevitably my approach has been I can't win, so let's just get then to, (A) actually get off a deck (if you watch videos of similar RC models you might think its impossible), (B) get it to actually attempt to fly slowly, no one can expect a model of this size to hover like a butterfly, and (C) achieve the really tricky bit of getting down onto the deck whilst  not wrecking the model and/or dying of heart failure in the process!

We, as a carrier group, have evolved rules and techniques of deck handling which helps a lot and proved that this type of model is possible. I will leave links to other pages covering that and more. I just hope others will give it a go in the spirit of advancing what we can actually do. Three regular comp flyers, I include myself in that, at the time of writing, have managed to have some success. 

This is a field where experimenters and hackers can have fun, or just have a go for the buzz of flying something different. 

However, if  you like pot hunting, stick with what you know, or it will be very long hard road to achieve even similar results to conventional models. As you will become aware, most of these models will be of the foam moulded variety. As carrier can be a brutal game, the necessity of identifying and strengthening potential week points is absolutely essential, as is the knowledge of how to modify and  and repair severe damage at times. Unless of course,  you happen to possess a bottomless credit card limit that can be splurged on a new model after every disaster.

The model

The model: FMS F-15 V2 

Wingspan: 715 mm

AUW: 1025 g

Wing Area: 15.5g/sq dm

EDF: 64mm 11 blade. Motor 2840-KV3150

ESC: 40A

Servos: 9g x5

Recommended battery: 4S 2600mAh  35C

Take the above  battery recommendation with a pinch of of salt for Carrier flying.

I did my initial flights with a Tattu 14.8V 4S 1800mAh 75C battery and have recently flown it with Tattu 14.8V 4S 1300mAh 75C batteries. The 1300s are half the size of the 1800s so more lead in nose was required. if you had an exceptionally  long slow lap  time with the 1300s you may run out However  model of this size do not fly slowly :) I would also mention that Tattu batteries are the best I have ever used! Other brands may vary; experiment!

Hacking it

The normal problem of how/where to mount the bellcrank/s is exacerbated with EDFs, becoming problematic when  there is a bloody great EDF unit blocking the fuselage where a pushrod would normally be routed.

There are no rudders on this model just solid vertical fins. As the fins are large I thought they would probably have enough weather vaning authority to cope, so I left them alone.

In this case the model also has spit elevators as well as being raked back at an angle. This would make linking the two together a bit of struggle as the hinge line would pass through the jet efflux moulding. The last thing you need with an EDF is anything blocking the fan exhaust.

Applying knowledge gained from previous EDF exploits, the solution was two external bellcranks either side of the fuselage mounted on a plate that extends all the way through the fuselage. the plate was  thinned out in the middle to try and reduce the  turbulence entering the fan unit; not sure how effective that is, but worth a shot.

Note: there is one alternative solution that would work.  With controlline models it's perfectly feasible to fly with only one half an elevator. This would mean only having to install one bellcrank, making everything much simpler to install. The only possible down side, is that the ideal  elevator  half to operate is the outer (relative to the flight circle) as any induced rolling will be outwards. Rolling inward is not a good idea. I'm sure either would work but I would try the outboard version  on an old model first.  The only downside is that the bellcrank has to be mounted on the outboard side of  the fuselage. However two wires passing through the fuselage would be less work than installing a plate.

Externally mounting bellcranks on foam scale models is the easiest way if the layout permits it. Though  it can look awful on nice clean upper surface, underneath is better but still not brilliant.

Onto, and next to, the under wing fuselage sides was an acceptable compromise. It also meant that both bellcranks could link directly to each elevator which were originally operated by two servos.

Removing that plastic cover that runs the length of the fuselage was quite a challenge. I have no idea what glue was used but it was exceptionally strong, There is always a danger trying to remove something like this of ripping off chunks of foam in the process. Fortunately I managed and could also cut off the section that covers the EDF. I can now get at the EDF without having to remove the whole of that plastic strip each time.

I'm fortunate enough to be able to 3D print small parts, but for the most part plywood could be used, or metal. The main advantage with 3D printing is being able to custom design parts to fit or replace things. Weight is not one of it's saving graces, but careful design and some specialized filaments can help. Printing covers for holes where where I removed servos was a case in point, printed with grey PLA or PLA+ for stressed parts, they blend nicely with the rest of the colour scheme. the white does not but it was all I had before the grey eventually arrived. I've also modelled the nose cone as I'm sure the foam one will disintegrate at some point. It's  been broken once but I managed to repair and touch it up. 

The next job was to remove the nose wheel steering and servo to create more room and lock the wheel into a straight position.

One thing that became clear early on was the bad design where the fuselage joins the intakes. It's a high stress area, especially as the nose is long and the  U/C having a lot of leverage with a hard landing. It definitely could have done with some carbon rod support running the length of the nose and beyond either side. I did the best I could in the confined space but it was a hopeful bodge; indeed after few landings the stress marks are visible. The amount of flexing going on was visible in my  last two landings with the nose and canopy popping off each time. I subsequently managed to get a more secure fit by carefully removing material from the front of the fuselage to allow the magnet in the nose to get closer to whatever material in there it needs to stick too.  The canopy I'm not sure yet as it's always stayed put before.

When having to get at something on a foam model, I have learned not to be timid; it's easier to slice off a complete wing tip ( sharp kitchen knife will do the job ) than faff about cutting holes in the surface. Cut along and panel lines and stuff a tip weigh in the thickest part of the wing, a mess wont show, then glue back the wing tip. Spot gluing also helps in case you  need to cut it off again. the original panel line will help disguise the join, unless excessive amounts of glue are used.

Thus I attacked the fuselage in same manner. Cutting a large section out made it easier to align things and peg the bar for double measure. I was quite pleased at the end result.

Adhesives and foam can be problematic; with most being far to strong. I always tend to use UHU POR sparingly spot joining or in very thin layers; it's easy to get hold of and it's grab properties allow for a bit of repositioning if things go wrong before it sets; its rubbery state means things can flex without breaking a joint;  cutting  through when cured  it can be a challenge.  Epoxy works well but is over strong unless something very permanent is needed. Thin Aliphatic adhesives are good but tend to discolour in the bottle as they age leaving ugly hard scars. Cyano adhesives may be quick but can also have unexpected results with foam at times; they can also be very hard to cut through if you make a mistake.

The original model had no flaps. I never use ailerons as they are very effective, a bit too much so. There is only need to have the outboard aileron move up slightly to have a large effect. I just fix the in board at neutral and have the outboard up by a couple of mm. having removed the servos I  just re cut the holes a bit further inboard and use them for flaps.  Making a first mistake. For some reason I decided to rotate one of the servos to get the the pair to move in unison; after lot f hacking and cutting I realized I didn't need to. Oh woe is me, what a **** ! Add your own expletive.

 Cutting out the flaps was easy, chamfering then to get a desired  droop was a bit more fiddly, with me nailing the inevitable F****! up of chamfering one in the wrong direction....! I managed to pack out the hinge line and hide the rest of the damage, but not to my ego at this point. Make as few mistakes as possible when working with foamies as trying to touch up colour schemes can also be nightmare, some shades are almost impossible to replicate.

Next was positioning the line guide. With all swept wing designs this can be a pain to make so it doesn't look ugly or out of place. Add to that the vertical position of lead outs is often overlook but just as important as any rake. It's possible to get some sense of where the vertical CG is by hanging the the model (including batteries) up by the leadouts, or temporary leadout guide, and looking from the front or rear of the models it will be easy to see if the wing is at least roughly parallel to the lead outs or off either side. Imagine the whole thing with you holding it as you are, rotated around 90 degrees. If it looks how you imagine it should when flying level you would be good to go; if not then the line guide  position needs moving up or down until the lead outs are as level as possible. This in effect means the lead out guide, the pivot point of the bellcrank, and CG are all aligning in a vertical direction with the model horizontal. This should avoid any bad  outboard wing up or  down flying behaviour.

Rake is matter of preference. I find myself myself using less these days, rudder offset seems more effective and causes less strange behaviour at low speed

Once again I ran off a 3D design for leadout guide trying to make it look like like it may have been a possible rack from the real aircraft. It worked out better than I expected.

Almost the last thing was working out how to make an accessible easy to adjust and maintain hook release assembly. This has always been difficult on the other EDF jets I have converted. The common arrangement I came up with is to have a pivot bar with bearings either side to spread the load ( the foam skin is not thick in that region ).  On one model I had to do this because the EDF unit sat  sat right beneath it. With this model it was the ESC. The release servo is mounted at the rear for similar reasons.

All this work was to hide as much as possible underneath so the view from above is as uninterrupted as possible. I know it sounds a bit petty and needless, but first impressions matter, and usually last. Who knows? Someone may see it and say, "That looks good, I'll try that myself." That is certainly the effect some models have on me.

What do you think?