Rubber Band Power

[southwestforests]

Originally Posted by mbauer

Going to get serious about buying some tracing paper to run through my big printer/plotter and use balsa for the internals. Wonder how the ink will hold up to the dope covering?....

Related yet different - Sometimes making signs and labels for trains and miniatures I've taken small things printed on regular printer paper and sealed them by starting from the back of the paper with brushing on Tamiya clear acrylic paint so it soaks through the paper and in to the ink without brush strokes dislodging the ink particles. Occasionally there was slight bleeding but acceptable for the purposes I was using the prints for. Waited for the clear gloss applied to back of paper to dry before brushing on the front.

Last spring I got a couple different grades of rubber motor from FAI for use in a rubber band powered balsa wood submarine I built in 2005.
Have historically used 3/16 in 2 loops, got 1/8 to try in 3 loops but Missouri River flooding got between me and the test pond and the test went undone.

Yes, the rubber lube makes a difference, and probably a bigger difference in aircraft than in a free-flooding submarine hull where the lube gets exposed to water and rinsed off.

Just for grins,

[yukonjohn]

Originally Posted by mbauer

Going to get serious about buying some tracing paper to run through my big printer/plotter and use balsa for the internals. Wonder how the ink will hold up to the dope covering?....

Sounds like you are working toward stick and printed tissue models. I used to check in with the earlier versions of the Bradley's website in years gone by:
Paul and Ralph Bradley's Model Airplane Hangout
Lots of info and techniques here if you haven't been there yet.



John

[southwestforests]

Hey, will have to go check that site!

Here's the stick and tissue website I go look at from time to time, Mike's flying scale model pages

Welcome to Mike's flying scale model pages

The purpose of this site is to show examples of free-flight flying scale models mainly from the UK, together with useful information, hints and tips for fellow builders. If newcomers to this fine hobby find encouragement here, then so much the better!

My main interest is in traditionally constructed scale models, built using a balsa framework covered in tissue. Motive power is usually electric, CO2 or the traditional rubber strip motor. It is years since I built a model with an internal combustion motor in it - nowadays there seems to be a move towards quieter, more "enviromentally friendly" power units, so CO2 and Electric are becoming more popular, and there are even compressed air power units available. The appearance a few years ago of Rapier solid fuel propulsion units also lead to an entertaining detour into the wonderful world of small free-flight scale jets.

[mbauer]

Originally Posted by southwestforests

Related yet different - Sometimes making signs and labels for trains and miniatures I've taken small things printed on regular printer paper and sealed them by starting from the back of the paper with brushing on Tamiya clear acrylic paint so it soaks through the paper and in to the ink without brush strokes dislodging the ink particles. Occasionally there was slight bleeding but acceptable for the purposes I was using the prints for. Waited for the clear gloss applied to back of paper to dry before brushing on the front.

Last spring I got a couple different grades of rubber motor from FAI for use in a rubber band powered balsa wood submarine I built in 2005.
Have historically used 3/16 in 2 loops, got 1/8 to try in 3 loops but Missouri River flooding got between me and the test pond and the test went undone.

Yes, the rubber lube makes a difference, and probably a bigger difference in aircraft than in a free-flooding submarine hull where the lube gets exposed to water and rinsed off.

Just for grins,

This photo is great! That sub look like it is lots of fun.

Notice you have a winder. Might need one since getting ready to do 1/4" rubber for a 9-1/2" prop, in two loops for the next phase of my build.

Mike

[mbauer]

While the Phase Three model is printing:


Will mention some of the changes.
1) Model has been up-sized to 30" Wingspan [76.2cm]
2) Printed on 90lb Index [162.8 gsm]
3) Wheels will now be tires instead of discs
4) Balsa cut for Wing Spars
5) 1/16" [1.6mm] thick balsa will be used for fuselage internal supports
6) Learned how to create a new color in AutoCAD, using it instead of gray to better match the real color of my airplane
7) 1/4" Wide [6.3mm] Rubber Band will be used with double loop
8) 9-1/2"Long [241.3mm] Propeller will be used


The balsa wood wing spars have been cut. Two each 15" Long [381mm] will allow for dihedral. Will glue and clamp together to hold correct dihedral when drying with clothes line clamps.

Wing spar is exact height of highest point of airfoil shape. I plan to insert the wing spar through the fuselage, once properly glued into position with proper dihedral, wing skin envelope will slide over the spar, then tabs inserted into fuselage as normal. Hoping the balsa will maintain the proper airfoil shape without needing any ribs.

Fuselage will have minimal 1/2" Wide [12.7mm] x 1/16" Thick balsa internal supports. Wing spars will penetrate through one of these supports. Supports will be box shaped when done.

Hoping the paper tube will with stand the double 1/4" rubber motor winding, and the tail hopefully will not kiss the nose.

Printing is done!

Quick lunch and then time to cut and build.

Mike

[mbauer]

Originally Posted by southwestforests

Just for grins,

I'm liking this sub the more I think about it. This your design? Or are there kits somewhere?

Mike

[southwestforests]

Originally Posted by mbauer

I'm liking this sub the more I think about it.

Thanks!

This your design?

Partly. Is my upgrading of a very basic late 1960s early 1970s design from a book for kids.
Only took me 30 years to get around to building it!

Or are there kits somewhere?

Not that I know of.
My model was based on instructions which are one of the projects in back of this book.
Model in book has no stern planes; rudder is sheet tin you bend; screw is likewise bent out of sheet tin; and the rest is likewise that basic.



honestly, the following images may be just showing off.
They are from around 2005 - 2007
Wound and trimmed right this thing has hit 7 feet deep.
Note last image, hazy dark spot under bow is pool drain.
Model is ballasted to float with deck awash.
Is dynamic diving, with power on it is forced to dive until running out of winds.







Beginnings of one for a friend in 2008 will give a hint at construction method.
Bottom is 1/2 inch thick balsa plank. Sides are 1/4 thick. Deck 1/8 thick.





Here's full album, includes a short video from a couple years ago.
https://flic.kr/s/aHskzXRFGp
Pool person was enlisted to take video with my camera. For some reason they didn't get the full run. Sub will go full length of that pool with last 20% on surface. In shorter pool in town where model was built it would tag far end while still submerged.

[mbauer]

Made good progress yesterday.


Three sides of fuselage glued, rubber band tube installed, wing spars glued in placed:


Glued cured all night looking like the above photo. Balsa blocks give it 1-1/2" High Dihedral for stability when flying. The 3 deg wing incidence allows it to fly nose down when in level flight.

Here is a closeup of the wing spar glue joint, it has been glued to the balsa support on the bottom, but the sides have not been glued until the top skins get applied:


Weights:
a) Wing Spars weigh 5.77gm each
b) Rubber Band Tube weighs 10.28gm, when rolling around 5/8" wood dowel last 30% gets sprayed with 3M 77 spray before final rolling.
c) Fuselage w/ 3-sides glued, rubber band tube installed weighs 39.65gm
d) Fuselage w/wing spars glued weighs 51.26gm

Will install rubber bands next, super glue the tail wheel spring wire and assembly to the fuselage bottom, then glue top of fuselage skins on. Tail section first then the top engine cowling.

Leaving the Canopy open, the next step will be to glue the wing skins to the fuselage.

After glue dry's the next step will be to add the horizontal stabilizer/elevator and rudder.

Will then do a final glue on the canopy before adding main landing gear.

A few steps left.

The rubber band tube for this size is a little short. Used the full length of an 11" x 17" size sheet of paper. Should be 1" longer, but did not want to roll a 24" x 36" sheet and then cut the correct length. One advantage is that the rear mount is 1" closer to the CG with means less counter weight is needed to balance.

Mike

[mbauer]

Ok, completed phase three build.

Short acceleration run in kitchen shows it has power.

Double 3/16" rubber bands give it some go power. Still need to weight and balance for flight, but looking good so far.

Finished weight before weight and balance: 4.3 oz so big time heavy weight, but the 9.5" prop does move it good.

Inside fuselage look at balsa wing and fuselage support 1/16" thick supports. Four pieces create a "box" to handle flight loads:




Attaching Wing Skins. Just slide on and then insert tabs into fuselage before gluing along entire length with fuselage wing. This creates a fillet glue joint on top to give it strength and helps with airflow:


All three of the builds so far. The paper one is not going to last long, any handling and it just caves in:




Here is a close shot of the 30" Wingspan 4.3oz bird:


Well, have other projects to do. Did order a roll of tracing paper to see how it will work.

Might need an electric motor to get this one in the air after weight and balance....Going to be HEAVY!

Mike

[mbauer]

Originally Posted by southwestforests

Thanks!

Partly. Is my upgrading of a very basic late 1960s early 1970s design from a book for kids.
Only took me 30 years to get around to building it!


Not that I know of.
My model was based on instructions which are one of the projects in back of this book.
Model in book has no stern planes; rudder is sheet tin you bend; screw is likewise bent out of sheet tin; and the rest is likewise that basic.

Here's full album, includes a short video from a couple years ago.
https://flic.kr/s/aHskzXRFGp

Getting ready to check the album. Just looked on ebay for the book, no luck but there are three of the Aviation books from this series for $8 each.

That sub is totally awesome. Great photos of it diving. Really like the prop wash when near the surface.

What did you rig up for the prop?

Just watched the video. It really moves out fast!

Mike