Yellow Bird (oz7648)

 

Yellow Bird - plan thumbnail image

About this Plan

Yellow Bird 20. Chuck glider model.

Quote: "A 'How-to-do' feature on high performance chuck gliders. Yellow Bird, by AJ Webber.

Do You Want a contest model you can fly on the village green and not end up in jail? Then Yellow Bird's the answer! The aim at all stages of development has been to obtain a safe launch in rough weather, have ability to recover from gusts and eddies and maintain sufficient altitude to catch thermals, rather than to rely upon fresh patches of low-level lift.

This might be expected to produce poor calm-air duration; but that is not the case. Flown after sunset on three occasions last summer the larger 'YB' 20 recorded a tranquil 90 seconds plus on each outing. Careful trimming on damp evenings gave maxima of 65, 58 and 74 seconds.

The long tail moment, 40 percent tailplane and big fin keep the YB's on the right climbing track in rough weather. Less fin area is fine for the glide but allows swinging-off to one side on the launch. The 4.7 percent wing section is just right. Thinning it down produces no gain in height and sinking speed goes up sharply. Yet if it is thicker the rate of sink is the same; but on go the brakes early in the climb.

Both YB's will go over the 100 ft altitude mark and the adjustments used produce (1) something between 1/2 loop and right-spiral Climb under power, tending to nose up if the turn over-tightens and (2) a very flat, safe left glide circle.

Building the YB's to lower all-up weights than those shown does not improve performance. Increasing the weight may give one extra time, but calls for more force in the throw. Bamboo leading edges are well worth the extra effort, placing tremendous strength where chuck-gliders take all the knocks. If necessary, "borrow" a piece off the neighbour's bean-poles.

The dangle dethermaliser causes a curious descent but landings have been effected safely on roofs, hawthorn trees and other unfriendly objects!

Colour-scheme on the originals was yellow wings, tailplane and black fin with black trim on fuselage. For elegance this takes some beating. Orange, used on two of the later versions, gives remarkable visibility.

Wood Selection: Cut wing, tailplane and fin from quarter grain sticks. This has a shining, mottled look and strong resistance to bending. If you have a choice, pick the lightest. Fuselage for the YB20 needs hardest spruce, straight-grained, without natural bends. Softer spruce (usually lighter in colour) for YB13, or, if you prefer balsa, use the hardest piece of straight-grained wood you can find.

Components: HMG Adhesive was used on the prototypes for all joints involving spruce and all joints are pre-cemented.

Curve the bamboo leading edges over a candle flame and cut for dihedral breaks before cementing in place. Finish - sand the underside of wing and tailplane and add the linen thread edging to all parts. Reduce the wing to the tapered thickness shown and mark the high-point line of the section on the upper surface. Study the section carefully and then carve and sand to shape, restricting sanding action to work from leading edge to trailing edge and at 45 deg. across the wing..."

Quote: "Hi Steve, Here's the Yellow Bird 20in HLG, sheet 1 of 2. Sheet 2 could be the 13in one, as I have both plans. Unfortunately I don't have the Aeromodeller issue. I tried to rework the outline of wing and stab as good as possible, which were overdrawn with pencil in my original plan. Now is the time to stop repairing and send you the plan. Regards, Wan."

Direct submission to Outerzone.

Update: article pages, text & pics added, thanks to RFJ.

Note: It looks like this plan was published along with the smaller 13in span version, see http://www.outerzone.co.uk/plan_details.asp?ID=3479

Supplementary file notes

Article pages, text & pics.

Corrections?

Did we get something wrong with these details about this plan (especially the datafile)? That happens sometimes. You can help us fix it.
Add a correction

Yellow Bird - completed model photo

Datafile:
  • (oz7648)
    Yellow Bird
    by Alan J Webber
    from Aeromodeller
    October 1961 
    20in span
    Tags: Glider F/F
    all formers complete :)
    got article :)
  • Submitted: 19/04/2016
    Filesize: 294KB
    Format: • PDFbitmap
    Credit*: WanBrouwser

003.jpg
003.jpg

Do you have a photo you'd like to submit for this page? Then email admin@outerzone.co.uk

User comments

I still have one of these in my loft, built about 1976. I took it out about 10 years ago - say 2008 - and something made me light the DT even whilst testing it. I am glad I did - second lob and it snagged a thermal and was away! I've been itching to convert one to micro r/c. Has anyone done so, I wonder?
Dick - 18/11/2018
Add a comment

 

 
 

Download File(s):
 

Notes

* Credit field

The Credit field in the Outerzone database is designed to recognise and credit the hard work done in scanning and digitally cleaning these vintage and old timer model aircraft plans to get them into a usable format. Currently, it is also used to credit people simply for uploading the plan to a forum on the internet. Which is not quite the same thing. This will change soon. Probably.

Scaling

This model plan (like all plans on Outerzone) is supposedly scaled correctly and supposedly will print out nicely at the right size. But that doesn't always happen. If you are about to start building a model plane using this free plan, you are strongly advised to check the scaling very, very carefully before cutting any balsa wood.

 

Terms of Use

© Outerzone, 2011-2019.

All content is free to download for personal use.

For non-personal use and/or publication: plans, photos, excerpts, links etc may be used, provided that full and clear credit is given to Outerzone with appropriate and specific direction to the original content i.e. a direct hyperlink back to the Outerzone source page.

Unauthorized use and/or duplication of this material without express and written permission from this site's owner is strictly prohibited. If we discover that content is being stolen, we will consider filing a formal DMCA notice.