Last time we finished up construction of our rudder/dorsal assemblies and built our offset rudder hinge. So, now it’s time to clean these assemblies all up and make them as ready as they can be to be installed onto the fuselage. The installation of the dorsal onto the fuselage will occur once all of the construction of the fuse is finished however. The primary reason for this is so that all work on the fuselage can be done without the dorsal being in the way as the fuselage is rotated around while it’s worked on.
Primer – Sand…repeat, repeat, repeat… With the dorsal and rudders being glassed (see Part 5 for that discussion), the first item of business is to start the Continue reading →
Fiberglassing and Hinges…now we’re getting somewhere!
With the dorsal and rudder shaped, the next step is fiberglassing and hinging each of the parts. I didn’t take many pictures during the glassing process (performed this before starting this blog), but I will talk through it a little bit. When I get to fiberglassing the wings, I plan to make a complete tutorial video. The pic to the left is ultimately what we are striving for…
Some Notes on Fiberglassing
Now, I typically don’t hinge control surfaces until after glassing. I’ve done it both ways (hinging before and after glassing) and have found hinging after glassing is definitely my preference. The reason for this is that when I make the slots in the control surfaces to receive the hinges, I can get much cleaner and crisper corners since the glass hardens the wood. Otherwise, the balsa can crush in around the slot and it doesn’t come out as cleanly. In terms of glassing, I use 3/4 oz fiberglass cloth and Pacer Z-Poxy Finishing Resin finishing epoxy resin to apply the glass. The fiberglass is cut out around the surface allowing significant overlap and laid flat onto the surface dry (important!). From there, I mix up the Z-Poxy Resin as directed (50/50 mix Continue reading →
With the final shape of the dorsal completed for our RC Jet, it is on to cutting out and shaping the rudder. On the full size Skyray, the rudder was split into an upper and lower half. The upper portion acted as a yaw damper primarily while also acting in unison with the rudder. The lower half acted as the primary rudder surface. Interestingly, in looking at videos of the Skyray in flight, the yaw damper doesn’t seem to act much in unison with the rudder at all. Also, in talking with Mark Frankel, the rudder is quite effective on the model causing it to roll pretty substantially. So, based on those two things, my intention on this model is to make the yaw damper fixed and use the lower half as the rudder. We will be cutting out both the damper and rudder and splitting them, but when final installed into place, the yaw damper will be fixed. This way, it will still appear to be a moveable surface.
Rudder template in place, ready for cutting
Checking my 3-view to the plans, I traced the rudder shape and transferred it to the dorsal. The key here when plotting it out is the allowances for the balsa rudder cap (in this case it’s about ½” of material) as well as the spar in the dorsal itself. In other words, ½” of the rudder leading edge will be removed and thrown away and replaced with a solid balsa cap that gets sanded to shape. Also, I had to take time to ensure I accounted and had a plan for the location of the spar so I had the proper scuffer setup on the dorsal as well once everything is hinged. The idea is to have a nice scale looking flange on the dorsal and rounded Continue reading →
When you build an RC jet like this one, it’s nice to start off small. Progress comes with small milestones accomplished by small steps at a time. It really only takes a few hours per week to see notable progress and the key is to just get into the shop and make that progress happen. Yes, it takes time and will take a while to get done, but that’s half the fun. So, with that in mind, I started off construction with the dorsal. Note that I started this build before starting this blog, so in some cases, I’m limited on the pictures that I took.
Sub leading edge glued in place
With everything unboxed and setup in my shop, the first item of business was sheeting the dorsal foam core (I plan to make a tutorial video on how to do this when I sheet the wings). Mark’s design incorporates a sub leading edge before sheeting, so that was installed first with some wood glue (I like to use Titebond Premium Wood Glue). The sheeting was made from contest grade 1/16” balsa (as light as possible) glued edge to edge as necessary to get full coverage over the core. The grain of the wood runs parallel to the leading edge (important!) which helps with strength as well as makes it easier for the wood to contour over the foam core. I used Pacer PT-40 Z-Poxy Finishing Resin to adhere the sheetingContinue reading →
Let’s talk about resources and documentation for Scale Competition for a minute…
If there is anything debated in scale competition, it sure seems to be scale documentation. 😉 I say this only from the standpoint that there’s really no one right way, or one right answer when it comes to a documentation book. It’s ultimately how well you prove your model matches your documentation. Also, I bring this up at the beginning of this build because, without a good solid documentation book, it’s very difficult to be competitive in a scale competition setting (static score is HALF of the total score). Plus, if you are building your competition bird, it’s necessary to have a clear vision of the project from the start.
First of all, it’s important to know the rules. For this bird, I will be primarily competing in the Scale Masters competitions, and so have gone through those rules numerous times (as well as have competed several times previously). USSMA also has a decent aid on their website for how to put together a quality documentation book. So, before starting, know what is necessary to present to the judges and have sufficient documentation for your aircraft. From the start, a good 3-view resource is necessary so that one can ensure the shapes of the model match the drawing. The paint scheme can evolve as the build progresses as sometimes you may have something in mind initially, and in the research process you may come across something you like more and/or can document color and markings better.
For me, I love the research and will typically buy whatever books I can find (it’s kind of a sickness that my wife gives me a hard time for) and spend numerous hours searching the internet. For the Skyray, there are two definitive books that are absolutely a must for any Skyray fan and are listed below. Also a must is a plastic kit (if available) as it helps to visualize shapes Continue reading →
I’m starting this blog with a series titled, “How to Build an RC Jet.” The subject of the study is a Mark Frankel F4D-1 Skyray kit (I love deltas!) of which I plan to build into a competition ready model for the US Scale Masters (and/or Top Gun if I can ever afford the trip some year). As I build the kit and document it here, I plan to cover not just basic building techniques (including tutorial videos along the way) but also all of the details that go into a competition model and the tools that are used in the process. These techniques are extensible to any model aircraft project and so I hope that I can provide anyone out there reading this some basic tools to do something out of the ordinary.
Regarding some specifics on the kit, the design is an exact 1/7 scale which puts the fuselage length at 77.6″ and the wingspan at 57.4″. This kit was first designed around glow ducted fan back in the mid to late 1980’s and flew excellent with that power. According to Mark, he designed it as large as he could while still getting a great flying airplane given the available glow power systems. The design has flown on glow and turbine power, however this will be the first to fly on Electric Ducted Fan (EDF) power and I expect performance to be excellent! Some of the features I intend to build into the airplane are:Continue reading →
The RC Geek Blog is your place to learn about all aspects of the RC hobby. Learn to build, design, drive or fly that RC project you’ve always wanted to build, but have been intimidated to try. This blog is here to help you on your journey and provide tips and tricks as you go! My hope is to inspire builders both experienced and new! So, welcome, please look around, it’s an exciting beginning! I’m currently documenting my latest competition scale RC jet build, a Mark Frankel F4D Skyray, along with some other fun tips and videos. If you can’t find what you’re looking for on this front page, click on any of the categories to the right and it will show just posts related to those categories. Please feel free to add comments and/or contact me directly if you have questions, I’m here to help! And don’t forget to check out my YouTube Channel, I post new videos every week!