"Scraps" Worldwide Covid19 Quarantine Online Model Build and Contest!
This page is a work in progress. I am making this page to try and help us all navigate the Facebook posts and threads
for the "Scraps" model people around the world are building and flying while we all are in quarantine for Covid19. This
page will nto be fancy just info and links.
What is a "Scraps"? It is a small simple plane that can be built in a few hours and flown in your living room.
The full size plan is here and was sacanned as 8.5" x 11", and when printed should measure 214mm flat span.
If it prints smaller, check your printer setting to see if it is
printing at less than 100% or set to "fit to page" or simlilar.
I set my printer to print "actual size" for it to print OK for me when using letter paper.
Here are Facebook links:
1. This is a "fly at your own place" event, such as the living room in your home.
2. "Scraps" model built per this plan http://www.indoorfreeflight.com/scraps.pdf
3. Model minimum weight without motor - 500mg
4. Balsa only construction, except thrust bearing, shaft, hook and tubes. Solid motorstick and boom.
5. Any covering material is allowed.
6. Rubber motor is unlimited.
7. Propeller is 5" max diameter. No VP. Sheet balsa, can be flat or formed any blade shape.
8. Each competitor can post videos of up to 3 flights on the FB page for the event.
9. Each attempt will be recorded and can not be removed. The final score will be the best one.
Other allowable modifications:
A dual thrust bearing may be used instead of a single. Any size music wire OK (no need to use paper clips.)
Wing posts can have tubes to adjust the wing incidence. Wing can be moved forward or back of the position shown on plan.
Stab may have undercamber. Any prop blade shape OK, camber and twist in the prop OK. Any dihedral OK (vee, tip, poly).
Trim the model as you see fit with rudder offset, washin, washout as needed. Use your favorite airfoils.
An offical entry will be a video of the entire flight posted to facebook or youtube or other public place that all can watch.
Any modern smartphone can take the video easily.
There is a wide variety of people participating in this with different skill levels from beginner to World Champion.
So categories have been made to help spread out the fun.
Max Time: this is for those flying for max time and allows steering the model when flying
No Steer: just like Max Time but no steering of the model allowed
No Touch: just like Max Time but the model is not allowed to touch the ceiling.
100mg Motor No Steer: rubber motor is limited to 100mg and no sterring permitted
1 Minute Club: break one minute and you are in!
2 Minute Club: break 2 minutes
3 Minute Club: break 3 minutes
4 Minute Club: break 4 minutes
5 Minute Club: break 5 minutes
"Stock Scraps", 1 gram min weight with stock flat prop per plan.
Spreadsheet with Current Standings
If you are looking to build one around 500 mg then you need to select your balsa wood. You want wood around
5-6 pound/cubic foot density. Here is a chart to help you find wood.
example: For 6#density, a 1/16" thick sheet 1" wide and 36" long will weigh 3.5 grams
Most hobby shop 1/32" wood is very heavy density because it is sanded
to thickness and light 1/32" will break in the automatic sanders.
So it is easier to find lighter wood in 1/16" sheet and then make it
thinner by hand sanding or planning the wood down to 1/32" or thinner
for the prop blades.
Here is some data from the Scraps I just made:
Wing spars: .030 x .040 6#
Stab and fin outline: .025 x .035 6#
Motorstick from 1/16" sheet cut 3/16" wide 5.5#
Prop blades: .015" 5#
Harlan EZB bearing
.012 music wire prop shaft and rear hook.
5% Simplex airfloil, flat stab airfoil
Polyhedral dihedral (1.5" total under each tip)
No wing offset
About 3/32" washin on left wing
Covered with 1982 Vintage lightweight condenser paper (spray adhesive)
Weight 508 mg
CG around 55% of wing chord.
Dave Lindley of Indoor Free Flight Supply is sending free rubber for Scraps models. See his website for details.
John Kagan has written an excellent tutorial for building a Scraps prop. I have resized it and save to PDF Scraps Prop Tutorial PDF
Here is John's original Word document with larger photos (file is 56MB) Scraps Prop Tutorial Full size Word Doc
Here is a CAD drawing of the Scraps by Tony Mathews click on it to download the full size jpg file.
Click here to download a letter size PDF of the CAD plan.
Added new class: "Stock Scraps", 1 gram min weight with stock flat prop per plan.