Rise of the Frankenradian

2m e-Motor glider

Thanks to Dennis Summer and Norm Peters as well as  the guys at the r/c groups build thread

Laser Cut Pod + Radian Wing

#011 (serial build number)

Radio: Jeti DS-12 Special Edition Carbon Grey

Receiver: Receiver EX R7

Variometer: Elite Micro Vario

Altitude Limiter: CAM Limiter

Battery: Tattu 3s 650 mAH

Servo: EMAX ES08 metal gear (flap/spoiler) EMAXES08 nylon gear (rudder/elevator)

Motor: E-Max 2212/980 kv motor

Spinner: aeronaut Z-Spinner (CN) 38mm

Motor Mount: aeronaut 3mm

Prop: aeronaut CAM Freudenthaler 10x6

ESC: Cobra 22A ESC with 2A linear BEC

Balsa and Bass Wood materials needed

Balsa Stick
1/2” triangle
1/4” triangle
3/16” x 3/16”
3/16” x 1/4”
3/16” x 3/8”
3/16” x 1/2”

Balsa Sheet
3/32”

Bass Wood Stick

1/8”

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Build Start Date: April 12 - May 27, 2024

Total build time: 38 hours

First Flight:

All Up Weight: 21.34oz

Build Notes: eMotor: You need to loosen the Allen screw on the motor and press the shaft through for mounting the motor the motor behind the firewall with bolts on the front. 

Retighten the Allen screw

Also hope you saw the note on the proper orientation of the firewall with T on top and centerline on the inside of the fuselage. Edit: mislabeled on my kit, printing goes outside to the front.

Wing: Use sharpened brass tubing for “drilling” clean holes in foam wing.

Push rods: DuBro threaded couplers #212

CG: The length of the boom was determined with a 3S650 for proper balance. You might use up to a 3S800 but would probably be nose heavy unless the boom was longer. 

On CG: 3" is surely outside of my comfort zone with this model. I'm at 2.75" with my Box-Stock Franken and it's good in most phases of flight. It does exhibit a definite"Tuck" tendency in a Dive Test, so I'm scooching my CG forward a bit. I know...

Plans: The PDF is saved as a 48”x36” size. Take the file to a Kinkos/FedEx on a thumb drive and they can print them for about $10.

Repair Notes: Destroyed May 31, 2024 on its maiden flight. Cause: pilot error, inexperience.

Errata: R/C Groups Frankenradian Build Log

605 grams or 21.34 oz

CG is at 2.84” at full length boom from Dennis measurement 

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The Back Story

As a kid, we had those big white styrofoam gliders. The wings plugged into the fuse, the horizontal slid into a slot. Just about all that thing could do is one big loop. A one trick pony, it sucked for gliding far.

That’s what a Radian reminded me of. 

Before I saw one fly.

Besides the prejudices I had against them, I really had not much of an idea of their potential. They were introduced while I was away from r/c soaring. I just didn’t understand their role in the scheme of things. I was given one to fly and could not turn away the kindness of this fellow. It was the version with ailerons.

It was rough, I gave it back before flying it. “John, I’m just going to build my Yellow Jacket.”

I wasn’t thinking about my lapse in stick time or their potential and I didn’t know how easy they were to fly or the potential it represented.

…and then I was asked if I wanted to fly a F3L RES glider.

Heck yeah! 

But it took so much effort to get the transmitter in my hands and thermals were not abundant on the weak Hi Start we were using,, a few seconds of flying, hand the controller back. That sucked.

But I was handed a Radian with juice in the tank! Power up, fly around, power up, repeat. First time flying in 25 or so years and before I knew it I had 15 minutes in the log book.

Pretty cool wing.

Fun.

You can read about that funny story HERE.

Another new friend pointed to a build thread about an upgraded Radian platform. POD and boom, tail feathers, a big flap cut in. And lots of pilots building them and such an easy build.

A community of like minds.

My way back in began to appear…

I fully believe that the Radian and its variants are a R/C Soaring calling card.

So in a complete reversal of my idea of what a Radian actually is, I’m eating crow and I’m going to build one myself. I’ll place my own spin on it. I’ll use it to get me started and more importantly, as an introduction to what I do. My friends, family and to people interested in what we do will be able to fly a r/c sailplane with just a little instruction.

They are certainly cool.

And this is the story of the rise of my Frankenradian.

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As with any kit I build, I typically wait till I have all the components before getting started. The boom was delivered broken so I had to wait for it and my decisions on which ESC and the rest of the power system. I didn’t realize I was missing much of the sticks to complete as well. The store I source my wood from is a good 40 mins by freeway. I’m traveling at the moment and when I get home, the store is a two minute drive from the airport we land in. All the parts are in so this weekend I will fully dive in and get most of the fuselage and tail completed.

In the meantime, I have been mining the pics out of the r/c groups build thread and rearranging them for study. I’ll be frank (even though I’m Adam) I learn more about construction from the community build threads than I do from a look at the overall build instructions.

The order is often a bit off as contributors will go back and forth so I take the photos and reorder them and also group them while I’m at it. 

*Composite photo of build images from r/c groups build thread

With the photos in a group on my iPad, I can study a bit and often solve a problem with construction. I really enjoy community based info. Case in point, drilling into foam with a bit is not as clean as a cut made with a sharpened end brass tube. This tip and many more have been read from the contributors.

* Please contact me if there is any issue with my linking to r/ groups and or posting this composite photograph. The “Radian” in Frankenradian is a commercial product posted at the r/c forums business site, where as this blog is non-commercial. 

The fuse side was mislabeled but keeping to the plan will keep everything straight and true.

The short kit for the FrankenRadian has a couple of mislabeled parts. It’s no big deal though as the plans are good and everything should be true to them.

I really dig these machinists blocks for keeping things square.

I prepped the ferrule by sanding the ends and tapering the edges. I used cyanoacrylate on the suggestion of the creator of the FrankenRadian. Prepping the CF tube with alcohol prior to bonding is important for adhesion. It’s super slick inside of the tube and the ferrule. 

Anyway, it’s drying/setting.

I don’t have a board dedicated to aligning and building a fuselage. So with a ePower model that has thrust compensation built in, it makes it a step or two more difficult. I love our granite countertop for building, it’s flat, I like my door panel, it’s flat however there is no provision for clamping down, it must be individually addressed. 

BTW, this is NOT an instructional build blog, it’s my personal reflections, notes and observations. I just share it with others as my way of giving back.

I always get nervous when I’m gluing and setting formers in the fuselage. Mistakes here can be costly.

I’m pretty happy so far, my method is not the way others build, it’s good but far more time consuming, accurate and detail at the cost of a lot of sitting and staring, thinking a couple of steps ahead.

The fuselage is straight. I’ll add in the 1/8” basswood stringer for the division tray. I’ll keep the balsa stringers for bending ease. 

It’s coming along fast! 

I screwed up and broke one of the back fairing tabs…

Ughh!

So how am I going to recover?

A piece of bulk balsa cut by a Japanese “dozuki” saw into an appropriate sized block, use a sharpened end of a brass tube to bore a hole through it. I used a pen to shade where to sand to get a tight tolerance flush fit. I’ll use a belt sander to rough the fairing shape, finish sand for a beautiful tail fairing. 

That’s how I recover.

Its nice when a fix turns out better than the original design.

Back on schedule.

I’m using basswood for the stringers all around. That will help with stiffness and general durability. 2/8” balsa is soft and will wear prematurely with normal wear and tear. 

I’m thinking of using a CAM altitude limiter. I like the idea.

The FrankenRadian is coming along just fine.

Soon I’ll have it finished and I’ll travel to the SWSS field to complete its first flight.

Tight tolerances!

Rough sanded, I’ll finish with hand sanding. 

I’m glad I broke the tabs, this fix is much much better, a great way to stabilize and support the boom for any landing less than smooth.

I added the divider stringer/rails. I also dinked around with the micro vario configuration and display on my DS-12. Man that little thing is accurate and configurable. 

I’m learning a lot.

New equipment compared to what I did some twenty five or so years ago is just awesome.

I’m going to not suck at this…

Doing inventory on the bits and pieces I’ll need to complete the FR. I am missing a CAM altitude limiting device. 

I want one, it’s a good idea.

I was contacted by a kind soul from r/c groups giving me really good tips. I want a two piece wing but not at the cost of losing a flap. 

I’ll have to figure that one out.

Boom length from tail one end is 29 7/8”

Total length of CF boom is 36 7/16”

I’m realizing how detailed I am but slow…

I can’t work on it after work, I’m tired and need a break. I am available early a.m. so most of my work hours are Friday, Saturday and Sunday. In the morning, my family is sleeping, no interruptions.

I’m happy with the progress, it’s just going to be a few weeks.

Then a month or two back before I start flying my contest builds.

I knew this was going to be a big commitment.

But I got this.

I think in between building sessions solving steps with my portable sailplanewerks. I’m moving now and am going to finish steps before I move along. 

This weekend I’m going to: 1. Solder connectors. 2. Finish boom end (sand platform, file pushrod exits) 3. Build spoiler servo mount. 4. Make and install wing hold down.

To finish, pod sheeting, build hatch and closure mechanism, join wing, cut and finish spoiler, instal spoiler actuator rod, sand/paint pod, fix hard points on wing, sand and cover empenage, set/glue down empenage, instal all electronics, make threads in wing hold down former, balance CG, level/glue boom, join control surfaces, set pushrods, put a fork in it.

Still lots to go but I’m closer than farther away…

The Radian wing is really cool for what it is, a mass produced EPO foam wing reinforced with wood ply and a CF spar. The shape is more than worthy. I joined the wing with a popular brand two part epoxy. To mate the wing halves I used a belt/disc sander and final hand sanding.

I’m going to source some CF rods for the plug in on the front former. The CF will do the wing justice but is not necessary.

I am excited to get it in the air!

I’m not going to spend too much time sanding. No perfect airfoil empenage, just a good foil shape.

I am going to name it, “Aliyah” for personal reasons. One of my last hang gliders was named that and it seemed fitting.

I think I’ll paint that small on the sides of the boom.

I used a dremel cylinder sander to saddle the boom

Looking through the tailcone boom holes.

I’m happy with the stab platform, it’s clean and the CF pushrod exit holes should be easy to do

I’ve accomplished quite a bit this weekend. Joined the wing, finished out the stab and wing mount, tedious stuff that takes a good amount of concentration. Tomorrow I’ll make the flap servo mount and solder up the ESC and battery plug then put it to rest till next weekend.

My 38mm Z folding prop spinner and blade assembly should arrive this week!

Then I can shape the forward pod and get the it painted and ready for electronics.

Nice clean and simple installation.

I got a lot done this weekend.

Next is the hatch fabrication.

That should go quick then some minor fitment inside the pod. 

I’m thinking three weeks from now, I’ll make the first flight.

I thought it would be cool to use the Rev. status on the extra ply.

I almost screwed up. 

There is a sequence of putting the latch together. It won’t thread through the small slot. So you have to glue in the back former with pin in, then spring and collet, compress spring set screw, then glue in the second former. Let it all dry, release and reset the collet. Press down the hatch, pull back and release a couple of times to dent the former, drill the hole in the former and it’s done.

This took me way longer than it should but it’s satisfying and now I’m done.

Time for final sanding, painting, install the electronics and on to the next thing.

Wow!

It turned out so nice!

I asked a co worker for a click pen, he took his out of his pocket and threw it to me. Unscrewing the cap, it was perfect.

His spring is going to do circles high in the sky.

Off recipe spicy nose cone and Z-Spinner

The recipe calls for a 10x6 but the motor calls for a 10x4.7 so I got a 10x5. These are CAM Z blades and I remember using Rudi Freudenthaler folding props before this time around. I have a set of the blades with his name on them I may use but Aloft says these are better. 

I don’t know.

I’ll know soon.

In the morning I’ll start rough sanding the entry behind the spinner. I’m going to redo the trace of the spinner on the bulkhead first. Everything is coming along nicely. I’m hoping I’ll have the wing ready to mount, the boom ready to instal pushrods.

Big picture looks good but lots of steps to get there.

I’m not looking forward to covering but I know I’m good at it and I know the monocoat hing works great.

I did some sanding and I used lightweight spackle to do minor filling. I’m going to paint it satin white and use a grey primer. Not going precision, just going through the motions. The goal for this weekend is to have the pod completely done + the wing spoiler/flap cut and ready. There are still sequences that must be followed if I’m going to use the boom length to balance.

Super happy with the results so far.

I dig the Z Spinner.

But I forgot how balsa sucks in paint. I used some light spackle and those areas are good. I really want to paint this balsa pod because I want to paint my Yellow Jacket 2m fuselage. I want to learn what works and what does not. Slathering on the spackle and sanding it off works. Dry balsa as in just sanding does not give a good finish. It’s hot today, 93 degrees with really low humidity. I’ll hit it with one more coat tonight, dry overnight, sand and finish paint. It will be serviceable and a lesson learned.

The paint turned out ok. I could have done a perfect job but I don’t want to spend so much time on it. The white smooth finish is fine. Another round of sanding and spackle would have it super clean and smooth. I learned a lot for my 2m F3L ships so the effort in doing it is good however, the FR is to build stick time.

Time to get the soldering iron out and get busy with the internals. 

I’ll finish up with all the connections and maybe build the battery divider.

I’m getting there, just slow.

Soldering was better than expected. The Weller really makes things nice. I had the right heat shrink and good connectors that I got from Aloft. I think there is a photo that I can follow wiring to get the rotation right.

No photo to check after all, no big deal but maybe some luck…

Turns out I’m lucky. I did a servo/esc/motor function test and it’s rotating in the right direction. Yeah! That motor screams in the open fuse. This is my first electric motor of this configuration. I see that extreme care must be taken to insure no wires or anything is against the motor body as it rotates inside the fuse.

Plenty of room in there. I am making gains this weekend. Once I make the divider in the forward bay, I’ll finalize the position of the receiver and clean up the wiring.

I like the collet on the Aero-Naut Z Spinner, it grips down and fits well. I’m glad that I went off recipe for it and the Aloft option being on back order helped too.

I have built the battery divider shelf and am going to pick up the wing next. I purchased some carbon fiber 4mm rod and will use that to mount the wing forward. I bought the 8-32 tap and nylon screws, that will better fit the 3/8” hard points I’ll put in the wing.

Lots of little things to do but I’m making gains.

Although it’s not much but I was able to create the battery divider. Tomorrow I will add in the stops on the rails. I used 1/8” basswood, I’m glad, balsa would have worn out fast.

I need to source a drill bit for the servo screws. I have a small pilot drill but the actual size, I need to find. I’ll try to remember to grab the pack before work tomorrow so I can buy at the hardware store during my lunch break. I would like to have the internals finished before this weekend. I want to tackle sanding and covering the tail feathers on Saturday, mounting on the boom on Sunday.

There is another SWSS member that has finished and flown their FR. I’ve got an invitation to fly with.

This Saturday is F3K contest this Saturday which I want to watch. I’m headed that way…

Servos, ESC and receiver installed! 

I’m happy.

Time to work on the wing.

Reasonably happy with the plug in. I used 4mm carbon fiber rods. I just used the brass tubing, picked out some foam and used a preset taped depth on a drill bit and hand twisted. I used skewers slathered in epoxy to wet out the holes.

I had to file the former by hand to get a tight fit for the wing on the fuse.

Cutting the flap was not easy. The cut is not perfect but utilitarian, it will do (pig.)

The Blenderm tape hinge took three tries, it came out ok.

I’m going to do some Mothers Day shopping to let the epoxy set.

Next is the bolt down thread cutting. 

I’m going in with confidence. The hard points came out well, the brass tubing cutter is made and I have a plan to get the holes pretty well zeroed in.

Making the hard points was satisfying. I believe I got everything centered up correctly.

NOW I’m taking 5 to get some Mothers Day shopping done.

Home stretch!

Some little things like cut nylon screws to length, add stops to battery tray.

Install flap pushrod.

Sand and cover the tail feathers, fix pushrods, exit holes on boom.

Balance by cutting back boom.

Set the boom.

Final assembly (add spinner) and again check control throw.

Done.

Weigh.

First flight.

Next weekend I’m out of town so 3-4 weeks more.

I missed painting control horn, ughh

Not much going on in the building department this weekend.

I’m predisposed with family commitments.

I did do some detail work in finishing nylon wing bolt lengths and an extra pair. I also cut and installed the flap horn and epoxied it on the flap. I’ll finish the flap pushrod install maybe next week after work.

I’m so close!

I got the flap pushrod and control throw done as well as the battery tray stops.

It was a good thing that I studied my DS-12. I was able to adjust the throw and now it’s full range and flap spoiler ready!

Just need to sand and cover tail - epoxy empennage on boom - cut and finish exit holes for pushrods in boom - install rudder and elevator pushrods - approximate CG - set (epoxy) empennage level with wing - final balance CG

I’m hoping to get the rudder and stab sanded and covered tomorrow. That’s pretty ambitious but I’m going to try.

It isn’t going fast but it is almost done.

All systems are figured out and purchased and working.

Ready to get flying!!!

Outside sanding at the glass table, almost too hot…

Home stretch for real!

Glue control fitting on pushrods, epoxy empenage on boom, make pushrod exit holes, balance and maiden it.

I cut the threads down to save on weight.

Measuring the pushrod exit holes, no need to figure that out again…

I wanted to use a friends CG machine but it looks like I’m going to do it by measuring and adjusting on my own.

I can do it then I can set the boom and BOOM!

Maiden time!

We balanced it on a CG machine and came to the conclusion that 7mm needed to come off the boom in order to get the CG at 2.17” from Dannis Summer at RC Groups, the producer of the FrankenRadian short kit. The measurements Dennis gave me and the configuration and placement of the internals was closely approximated and the CG came out to 2.84” 

Pretty damn close.

But experience from multiple pilots dictated a slight adjustment which I was able to complete with the help of a new friend Ed LaCroix at our club.

That’s the piece that was cut.

The boom is now in the process of fixing, glueing and I will cut and finish the pushrod ends, instal and adjust tonight, charge and balance my batteries and rise before dawn and drive the 50 minutes to our club field. 

Tomorrow is the day, May 31, 2024 I return to the sky!