Tercel (Bridi HLG fun wood build)

[Konrad]

As of late I've been suffering through about a dozen major glass and carbon rebuilds. Last week I was given this Tercel kit. I was thinking just what I need another build! But wait it is just what I need, a simple no expectation build. And an added bonus is that I built one of these as a teenager. I'm thinking I might be able to build it better now that I have gray hair. (Yes Doc. I have hair!).

Two things that are burned into my memory was the poor front hold down system for the wing. Anything other than a good hand catch and the wing tore off the fuselage! I also recall that the polyhedral braces were another bad joke. Even I as a teenager caught that error!

I also recall that any other 60" HLG could out fly the Bridi 50" HLGs. So I'm planing to extend the wings to 60". With that extension I thought I'd see if I can over engineer this build keeping as much of the original wood and parts as possible.

So here is the start of another build thread!

 

[jure]

I used to have a Tercel, received it as a gift from Ron , and re-gifted it in turn to Guy. A nice classic.
here is a video flying at Shell Ridge, Walnut Creek.
( it seems that it won't play unless you watch on YouTube, click on the YouTube text in the embedded frame )

 

[Konrad]

Wow, that's a great flying model and it handles the wind just fine! How much wind was there? I never sloped my Tercel. I'm now thinking that maybe Bridi and Deorfler knew what they were doing. I see that latter they did up the wing span to 60" with the Kastaway.

I was able to watch the embedded video.

 

[Konrad]

The reason the dihedral braces were put on the webs was to save Bridi from trying the die crush the plywood to make the bent brace. So there was a reason for their madness. I think a lap joint would have been better. I can only think the partial #2 bulk head was to save weight or money.

 

[jure]

Wow, that's a great flying model and it handles the wing just fine! How much wing was there? I never sloped my Tercel. I'm now thinking that maybe Bridi and Deorfler knew what they were doing. I see that latter they did up the wing span to 60" with the Kastaway.

I was able to watch the embedded video.

Konrad , this is a totally standard Tercel , 50.5" wingspan , Sloping at Shell Ridge.
Wind speed, maybe 12 mph ? .
And also thanks for letting me know that the video link works as it should.

 

[Konrad]

Is there such a thing as a standard kit built anything? I'm always adding my interpretation to things. I'm known for improving things until they don't work. Then backing off a bit!

 

[jure]

reminds me of my mentor, many moons ago , saying : " torque it just until before it breaks "

 

[Hank GB Z]

Signing on to watch. Hopefully join with my kit by the end of the year. Will you make yours motored, self launching?

Hank

 

[Konrad]

The “H” in HLG is Hand. But I did leave an electrical pass through should I need to put electronics under the wing.

 

[jure]

attaching two files from my collection:
Article and plans , sourced from outerzone.

 

[Wayne]

We used to have a few of them flying around on the beaches when I started flying, they always seemed to be a good slope choice as they were a rather simple build, pretty cheap and performed well for a 2 channel floater on the slopes. As an HLG, yeah, not all that great compared to other ships that came along after the Tercel.

I want to say it was one of the early KITS when smaller radio gear allowed smaller floaters to exist, not sure that is accurate or not?? There were some fun planes in that era that were similar. I want to say the retail price on the Tercel was around $20. They were cheap enough that lots of people bought them, but didn't seem like a lot of them were built, or maybe they just didn't last long??

 

[Konrad]

Yep, at sub $20* these were more often than not an impulse purchase. But what killed them was the cost of a "micro flight pack". As I recall a Futaba s133 servo was $40 plus then the Rx had to be a micro and to make weight you needed a 2 or 3 100 mAh batteries. So in the early 80's it was doable but not yet practical.

I built both the Tercel and Flipper. After learning the weak points of the design the second one lasted a good long time with little in the way or major repairs. I sold both at the Jefco Aeromodler's auction (Denver area) in the mid 80's. I wonder what happened to them. One was covered in blue metallic mica-film the other was in yellow mica-film. both had the fuselage covered in 1/2oz glass back to the wing hold down. and covered in white Ultracoat

I learned a lot about HLG with these Bridi gliders. I applied some of these lessons to my scratch built Larry Jolly's Flinger as published in Model Builder.

*I recall Mark Smith complaining that the highest cost item to produce these HLG kits and his Skeeter was the cardboard box!

 

[Konrad]

Proposed planform. This may change based on available wood sizes. I'm thinking of making the tip airfoil with zero camber. Maybe even inverted camber to mess with the air molecules (vortex control).

 

[Konrad]

Hum, not really liking what I see.

To save weight and time I dropped the end rib and then used the second from the end rib in its place. Keeping the as cut TE stock as the defining feature of the second panel. I then spaced the rest of the kit ribs as they fit the new taper. (Ok, the real reason I did it this way was that I didn't want to loft a new set of ribs). The rib at the mid span break look a bit too far away. So I might have to add an intercostal (in red) to at least the first bay.

I'm not concerned about fidelity to the airfoil as this kind of construction offers none. This is just a flat bottom wing with Phillips entry and an turbulated top surface. Yes, this is still an Eppler 205 mod. heavy on the modified! Now I will have to loft 2 ribs for the tip panel but that should be an easy step.

 

[Hank GB Z]

Konrad,

I’m liking your design work.

I mainly flew my tercel on the slope. As it didn’t need much lift it would fly well when a Zagi or other faster gliders couldn’t. Plus since it was HLG we could go over to the field by the slope and just throw it around if there wasn’t any lift.

When I build mine I plan to put a motor in the nose. I bought one of these motors for it already.

Dualsky XM2225EG-23 1600KV

The Dualsky 22EG series bring big power in small packages. They feature a diameter of a mere 22.4mm, allowing them to fit up in small aircraft noses as well as high quality bearings and an oversized 3mm shaft, so they'll be able to handle those less than perfect landings. Included are male and...

alofthobbies.com

Hank

 

[Konrad]

What are you doing for a spinner? These work great. But as they come from the Ukraine I'd get them now!

CN Models Spinner 25mm Collet Style

These super tiny folding propeller spinners are for use in electric DLGs. The yoke assembly is made from CNC machined aluminum, which is then anodized for longevity and the 2mm steel blade retaining pins are held in by the fiberglass reinforced plastic nosepiece, which feels quite sturdy. They...

alofthobbies.com

 

[Konrad]

Here I'm trying to show what I'm doing confounding various aerodynamic theories. (I'm just messing with the air molecule's small minds).
I'm happy that all I needed to do to add the 20% span was come up with 2 ribs. I'm throwing away the elliptical wing distribution theory as I didn't want to make bent LE and spars. I wanted to break up the tip vortex so I thought I'd use inverted tip airfoils. I also swept the tip aft 13mm help keep the shed vortex away from the wing TE in a deep stall.

On the other wing tip I'll try to show some in process photos.

 

[Hank GB Z]

Hey Konrad,

While I still haven't started my Tercel, i did buy the spinner your recommended and the 7x4 prop. I also printed a few copies of the nose of the fuse off and started figuring out how to lay out the motor, spinner, battery and servos. I will leave the fuse a little wider than stock so it matches the spinner but the hight will come down a bit. I'm pretty confidant that all the RC gear will be ahead of the CG.

Will you leave the stock solid tail surfaces or will you make built up ones?

Hank

 

[Konrad]

As I look over this project there is little of the original design left, other than the tail. So to still call this a Tercel I'll leave the tail stock.

 

[Konrad]

This is a photo essay on how I loft ribs during a build.
The key is to protect the master airfoils with tape. Also use sharp sandpaper on a sanding block. I like 150 to 220 grit sandpaper.