90 mph FT Viggen: GoPro on Board

by RaptorTech | May 9, 2014 | (8) Posted in Projects

Read the article first or watch the video up front: up to you!

Raw Footage from the day:

Flight 1  Flight 2  Flight 3  Flight 4 

(skip to the bottom for info about the camera mount)

The story of this Viggen:

After the Versa Wing, the FT Viggen was my second Flite Test plane. It's also my first jet style airframe, and, as countless other pilots have found, the Viggen kicks butt!

Although I seriously considered purchasing a speed build kit for this model, more to support FT than anything else, with the shipping costs it was beyond my high schooler RC budget. Instead I printed and cut out the free plans (which are great!).

I used Dollar Tree foam which I'm sure most of you are familiar with. If you are not, or have yet to try it out, I highly recommend it. Before I finally decided to order the 25 sheets of foam board for $25 dollars, I experimented with various types of CVS and Elmer's foam. Although flyable and actually quite strong, these locally available foam option were much heavier than the Dollar Tree foam and more than 5 times more expensive. Needless to say I'm a Dollar Tree convert. (Though Elmer's foam does have its uses as it appears to be stronger and more water resistant).

Over the course of several evenings and often while studying for tests I cut out all the parts:

After press-fitting everything together, I was quite impressed with the model

Now to figure out the motor.

Although I realize that the plane is designed for an EDF, I have never owned an EDF, and so I was unsure about buying one. Also, I am aware that EDFs pull a huge amount of power for significantly less thrust than regular propeller-outrunner combos, and, at the speeds most RC planes fly, thrust is more important than "exhaust" velocity. Also, the recommended EDF calls for a 4s battery, and my collection is all 3s.

But, the deciding factor was really was that I already had the perfect motor on hand. I installed a Turnigy NTM PropDrive 2700KV 600W motor with a 6x5 prop and a 50A Birdie ESC (all from HobbyKing). 

The motor mount was simply a wedge of foam with a piece of 3/8" ply, which I hot glued firmly to the wings.

Then it was simply a matter of installing some HXT900 servos with home-bent music wire pushrods and the electronics were complete.

I slightly reduced the size of the elevons by having them taper toward the wingtips slightly more than David included in his plans. This should, in theory, decrease the role rate and have less affect on pitch athority.

After hot gluing everything together I was ready for the maiden flight. It flew! And it flew well! Well until I squashed the nose, but hey, that's supposed to happen...

Flights and Revisions:

First and foremost, I added dual rates. I didn't bother with expo, but having dual rates was nice for low passes.

With the plane trimmed out and flying smoothly on my 3s 2200s (way up in the nose) and 3s 3000s, it was time to have fun. Here is a video of a recent flight on a 3s 2200:

3s is a lot of fun because I have a ton of those batteries, and, with the light weight 2200s, the plane has unlimited vertical performance. My friend was kind enough to lend a some 4s 3000s though, and with the higher voltage, the thing becomes a rocket.

We decided to clock the plane running on both 3s and 4s using two Hobbyking Dopper apps on different iPhones. On 3s, the average for the best pass was 70.4 mph. On 4s, the Viggen his 92.6 mph. As I should have expected the 50A Birdie ESC gave out on the 4s after only 3 passes. One second the plane was screaming along at 90 mph and the next I was trying to glide the thing back to the safety of the field. Luckily, the BEC didn't die and the wind was in my favor, so I managed to land the plane deadstick at my feet.

I swapped out the Birdie for a 70A RedBrick (not taking any risks :)) and several weeks later I was ready to try the 4s again. This time, I got several passes over 90 mph. On one however, I came in way too steep, and had to pull up quickly...

Folded the wings. Hot glue spar ain't gonna cut it for the 4s.

After a month or so of waiting for the carbon to come in, I cut off my old wings and added some new ones.

I pressed in 3 3x1mm carbon flat spars and secured them with hotglue and packing tape. 

With plane back in flying condition, I decided it could use a decent color scheme. I went with black and orange wing tape for visibility, but I think it looks alright too.

On the bottom there are stripes of black and orange running front to back, so orientation is not a problem. I have not made any modifications since. (These colors happen to be my school colors, and several people have approached me and suggested I fly a halftime show or something a sports event. Could be fun!)

The Camera Mount and Modifications:

On the above setup, I have had about 30 flights and got pretty comfortable with the plane, before I decided to throw on a GoPro. It was a little spur of the moment, but I figured it would be fun if not stable seeing the world from the perspective of the Viggen. I added a mount and hit the field all in one morning.

First, I took my old bent nosecone and lopped off the front 3 inches. I stregthened the front with several more pieces of dollar tree foam and hot glued to wedges of pink insulation foam onto the side.

I cut a bit of a notch into the walls of the nosecone and pressed in the GoPro mount. I ran 1.5" woodscrews through the mount holes and into the pink foam to secure it. I then wrapped the whole setup in strips of fiberglass packing tape to hold everything still.

The mount is the upper half of a handlebar mount designed to clamp around a bar. I didn't use the lower half. The camera and mounts are actually not mine, so I had to be careful not to get any hot glue on it, hence the screws and tape.

All it took was a few pieces of tape to attach the nosecone to the plane.

Even with the little 2200 3s all the way at the back of the battery bay the plane was still very nose heavy, so at the field I taped on big heavy nut to the tail, right behind the vertical stablizer.

GoPro Viggen ready for takeoff!



Thanks for reading! This was my first FT article as well as my first public YouTube video, so let me know how I did and what I could improve on. Comments appreciated!

I plan to post more content both here and on YouTube, as well as on my own website

YouTube Channel: https://www.youtube.com/channel/UC5bTux0AVaN9tBEbeR8rmHQ

My Website: izzybrand.com



noah on May 29, 2014
surprisingly stable footage. Nice work!
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RaptorTech on May 29, 2014
Thanks! I just edited the article and added links to the raw flights. You can probably see that it's not terribly stable, but you're right, it's not that bad either!
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TehMaxwell on May 29, 2014
Great Footage and an awesome article! Can't wait to see more from Raptor Tech in the Future!
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RaptorTech on May 29, 2014
Thanks! I have about 5 articles worth of videos and pictures all for scratch built planes, so you can expect to see more articles soon! (Or at least after the month of waiting for FT to approve the article)
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thejosh108 on May 29, 2014
I love taking a really fast one into those spinning dives, cool flying man, but i was wondering how is it that you know how fast it actually flies? radar gun?
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RaptorTech on May 29, 2014
For testing the speed I use the hobbyking Doppler app. In this particular case I had the app running simultaneously on two phones and I took the average of each pair of speeds. The app is said to be fairly accurate (you can actually test it on loud youtube videos) but for one run I got 55 on my phone and 191 on my friends iPod, so obviously I threw that reading out.
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nerdnic on May 29, 2014
Very cool but be careful. You're already pulling over the rated specs for that motor with a 3s 6x5. 4s is putting you way over.
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RaptorTech on May 29, 2014
You're 100% correct. On 3s the 6x5 was fine, but on 4s the motor got so hot that the collet on the end of the shaft was too hot to touch. Now for 4s I prop down to a 6x4.
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jayman72 on May 29, 2014
If you want it too live with 4s you could try a 5x5. Either buy one or trim a 6x5 down.
You will loose some thrust punch but it will have a higher pitch speed and therefore top speed, and with 4s should still be enough thrust but esc/motor current would be under control more.
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RaptorTech on May 29, 2014
I do have an old 5x5 but it's currently pushing around a 70% blunt nose versa. I don't fly the Viggen too often anyway because I think it's pretty rough on my 20-30C LiPos, and I have gotten some noise complaints because you can hear it almost a half mile away.
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jari on May 17, 2016
I'm surprised how well it seemed to fly in the video with that gopro setup. Nice job. Hope to see some more videos...

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90 mph FT Viggen: GoPro on Board