Bellanca Skyrocket (oz15667)

About this Plan

Bellanca Skyrocket. Radio control scale model. Wingspan 36 in, for electric power.

Direct submission to Outerzone.

Update 18/11/2024: Added article, thanks to RFJ.

Quote: "Bellanca Skyrocket. A 36 in span electric powered model designed by Peter Rake, with the prototype built and flown by Pat O'Donnell.

While hunting around for suitable subjects to draw up as plans I happened upon a rubber power design for a Bellanca Skyrocket. Although cabin monoplanes aren't really my sort of thing, this one is just gawky enough to appeal to my slightly perverted sense of the aesthetic.

Sleek and elegant may not appeal to me but boxy and angular does; besides, I've been rather taken with this type since I saw the David Boddington Bellanca Skyrocket (oz4149) model many years ago - without actually managing to build one. So, with all the right boxes ticked, it was just a matter of deciding what scale at which to draw it and how complicated the model should be.

At the time I was in a period of 'going back to my roots' in terms of electric powered models. Retaining modern power systems, but attempting to recreate simple-to-build models of around 36" wingspan -much like my first successful electric scale models some 20 years ago. As a result, I've tried to retain the simplistic approach of the rubber power model, but combined that with my usual style of construction. I think the blend works quite well, and certainly makes for an eminently flyable model. Now I just have to hope you agree with that.

As is usually the case with these models, I offered the design for prototype building through one of the online modelling forums and Pat O'Donnell was kind enough to volunteer to do the honours, As you can see, the result is the rather pretty (in an ugly sort of way) model you see here.

Power: The key to success with these models, apart from building them straight and light, is not to over power them. Originally Pat enquired about a set-up capable of 150 Watts, which is just a tad excessive for a model that should weigh very little more that 12 ounces. Okay, it's more than three times as much power as required.

Despite what many will tell you, there is such a thing as too much power, especially when coupled with the wing section I favour on my models. It's pretty much a one-speed section, so all that too much power does, is to make the model climb like a thing possessed. Reducing the throttle isn't always enough because it gets imprecise at the tiny inputs that would be required.

Although I suggest a power-to-weight arrangement of around 50 Waits/lb, that is the maximum you are going to have available, not what you'll actually require for most of the flight. In keeping with the prototype, slow and stable is the name of the game, not a scale version of Mach 2.

Pat ended up fitting an E-flite Park 300 outrunner and 800 mAh, 2S LIPo and a seven minute flight used all of around 400 mA. Even so, the take-off run (on grass) was around 10 metres and the model climbed out well. With a wing loading of around 10.5 oz/sq ft, the model will fly nice and slowly for leisurely cruising around.

Wings: The only thing you really need to know about the wings is that these airframe components rely on the spars for their strength, so don't be tempted to replace them with anything less strong than spruce. Bass is fine, but even hard balsa is not a good idea. The reason is that the spars, and where they fit into the fuselage and glue against F3/F3A, is all that stops them folding during more spirited flying.

The struts themselves do nothing other than add scale appearance. Don't let this put you off, I've designed (and built) several models using the same style of wing fixing and have yet to have a wing fold in flight - despite performing consecutive loops.

The reason I'm so fond of this system is that it provides a nice, neat wing-to-fuselage joint (the panels simply glue to the fuselage sides as the spars are glued to the former assembly) and automatically sets equal dihedral (and the correct dihedral) at the same time. Those little 'locating dowels' aren't load bearing. All these dowels do is ensure that the wing panels both go on at the correct incidence with the minimum of effort, while the spars set the dihedral. In fact, there should be no effort at all required to get the wing on correctly, just a little care taken to ensure a square fuselage and the F3/F3A assembly accurately glued in place.

With that proviso made, it's simply a case of applying a thin coat of 30-minute epoxy to the former and wing roots and sliding the spars/locating dowels into their prepared position..."

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