Harbinger Build

[Sled-Works 1]

For quite some time I have been making plans to build a Harbinger and well, that time has come. Numerous builders have made models of this bird so there are many fine examples out there for reference. Quarter scale plans by John Watkins are available through Traplet and then there are plans for a 2.9 meter version designed by Vincent Besancon that are available at Reroplane.com. His build log is exceptional, his building skills are amazing, and he was very helpful when I contacted him.
So after comparing the two plans, a number of three view drawings, and what photos and articles I could find online, I drew up my own set of plans and am now laser cutting a kit.

This is my first build log so it may take some time to get comfortable with it. - Sled

4 meter wingspan, 71” long fuse, ailerons, spoilers, elevator, rudder, tow release

NACA 4410 at root
NACA 4413 mid-wing
NACA 4409 wingtip

[lenb]

I love the Harbinger.
Maybe 5 or 6 years ago I had Tony Elliot expand some plans to a 6m version. I never built the model, hope to someday.
Thanks for posting.

len

[Sled-Works 1]

Hello Len - I wish my house was big enough to handle a 6m version. Hope you build it soon. The forward swept wing, wing struts, fixed wheel, tandem canopy, classic tail feathers, and the elegant sweeping fuselage...the Harbinger has it all. - David

[kjkavaney]

David, blow up your plans for a 6 metre and burn me a kit...I have the room to do one !!! kevin

[ARUP]

Nice! You doing the orange? It has 'crazy' spoilers'!

[Mosquito]

Excellent David! I was excited just looking at your plans and now we can see it being built. Great job. I will be tuning in frequently.

Tim

[Sled-Works 1]

I really like the orange but that decision is a ways off. Still designing at this point...and trying to channel my inner Mike Kelly. Cut the wing spar tops and bottoms on the table saw Tuesday and will cut the last couple plywood fuse former doublers over lunch today. Should be able to laser cut the wing spar formers tomorrow. I am definitely running with the wild spoilers as they are so unique.

In the photo below the trailing edge carbon and balsa sandwich is forming up. Should help look a little more scale than a clunky 1/2" wide balsa trailing edge. Surprisingly strong. - David

[ARUP]

So... David... this is the Harbinger. What else is to come?

[Sled-Works 1]

Not sure I follow you Arup, but right now I'm focusing on designing and making interlocking parts for the rudder and stab. The goal is to have the pieces come together in a way that holds them in place, makes guide holes for the Robart hinges, and interlocks them with other pieces for strength. In short getting more out of laser cut parts. Here is a typical sketch.

[ARUP]

You know... foreboding...dread... alarm... 'the harbinger of things to come'! This is a Harbinger, right? Don't pay much attention to me because my sense of humor is weird!

[Sled-Works 1]

Ha ha ha. You got me at my own game Mike. Keep them coming please.

After all the drawing and cutting lately I needed to glue a couple parts together just to see some progress. Here are a couple shots of the rudder this morning.







The notches in the leading edge center piece are there to act as guides for the Robart hinges...that will come later.


Gusset pieces in place. I'm certain this is not a scale detail but the profile is scale and they really do work well. Very strong connection.


Now with a few of the diagonal bracing members and bottom balsa block in place. Next up is to add the leading edge balsa and sand to shape.

- David

[ARUP]

Those gussets impart amazing strength! The hinge point pockets is a great idea. Lining those things up can be a chore so your detail eliminates that headache.

[Sled-Works 1]

I'm planning to use the gussets on the trailing edge of the wings as was done on the original. Between the gussets and the carbon at the trailing edge, I believe it will be plenty strong and look much more scale than the typical balsa trailing edge most models have.

Had a funny thing happening while laser cutting over the lunch hour yesterday. I enjoy playing the game of trying to get as much out of my scrap balsa pieces as possible. I was trying to squeeze in an extra rudder piece, eyeballed it, and this happened.


I raised my arms triumphantly. Ha ha ha.

- David

[ARUP]

Yessss! Excellent! I'm all the time 'scrappin' my planes together.

[Tango Juliet]

That's what you call, "Cutting it close!"

[Mosquito]

Nicely done David! That is very efficient.

[Sled-Works 1]

Ha ha ha. Sometimes it works and sometimes it doesn't. I haven't had too much time to work on this bird this week but managed to get the stab drawn up and cut. Should go together quickly this weekend. I like the way the pieces interlock and align...and it seems strong enough. More to follow.

[Asher Carmichael]

David, really nice work. Would you mind sharing some info about your laser?

[ARUP]

Yes... does it remove unwanted hair? lol Yeah, David... let us see some specifications or is it proprietary?