Rubber Band Power

[mbauer]

Originally Posted by southwestforests

Hmm, perhaps it is something about the small amount of heat within the freshly wound rubber? Or maybe the windings of the flexible strip migrate a bit and release energy while held static?

Not sure. It might be the elasticity of the rubber might not want to return to the original shape???? or do the fibers tear??

Keeping my eye out for more on the subject. Lots to learn about this. Reading that in competitions, flyers of free flight aircraft can expect 20-miles of bike or hiking conditions each day of the competition! That's allot more than the strenuous idleness of golf.

Have two different colored propellers that arrived. Blue 11" diameter and orange 12". The Orange are Huge! Needing a different sized shaft and thrust bearing for this monster.
Will outfit the 48" RV with the 11" for now.

The P47 is ready for flight testing. Hoping the gear modification works.

Mike

[mbauer]

Installed the 12" propeller yesterday. 9.5" looks small next to it.


Mike

[mbauer]

New model is the P40 Warhawk.

A couple of photos, still needs the landing gear added. 3ft Wingspan, 11" dia propeller.

Side view as the rudder glue dries


Flying Tiger


Red Lady with wings


Side view of both


Front View


4-total rubber bands, 3 each 1/4" Super Tan and one 3/16" Super tan.

Modified this build with a large opening in the rear to access the rubber band mount. Not sure how it will fly, but sure made the installing the rubber bands easier. Glad it did, because when I first installed the bands, wound it up. Was using a single rubber band that was long enough to create three loops inside the tube.

As it wound up things were looking good, when all of a sudden the rubber band slipped off of the propeller wire and knotted up inside the tube. Was able to reach through the larger opening and remove the bands without any damage!

Here is a photo of the opening and the wheels that still need added.


Other news? Started on a P38 which already has a couple of design issues.

Info when I downloaded the "paint" job reference photo said this is Tex Hill's Flying Tiger P40.

Mike

[yukonjohn]

Very nice work. Just thinking that if you are looking for a good subject, you might want to look at Aaron's Avenger. Tons of wing area, good amount of horizontal stab area, good amount of nose ahead of the wing, and even an opening at the ventral position for rubber access. Just a thought. Good luck with your efforts.


John

[mbauer]

Here are a few photos of the models that have been built.

The P40 was just finished. Needs weight & Balance completed.

P40 Specs:
36" Wingspan
3-each 50" long 1/4" Super Tan Rubber Bands (12.5 feet total length)
11" Diameter Propeller

After it was sitting on its gear, spun the prop a few times to see if it would move the model on carpet. Didn't do many turns, but as soon as prop was released it pulled the model easily.


Weight specs after W&B. Will weigh model after 24-hour time to let glue dry as much as possible. Once basic weight is known, will add tire weights until model balances for flight, tallying a final total at that time.

All Models Completed at this time:




P40




Mike

[mbauer]

Originally Posted by yukonjohn

Very nice work. Just thinking that if you are looking for a good subject, you might want to look at Aaron's Avenger. Tons of wing area, good amount of horizontal stab area, good amount of nose ahead of the wing, and even an opening at the ventral position for rubber access. Just a thought. Good luck with your efforts.


John

Hi John,

Thank you for the comments.

Purchased and downloaded it last year. Have an interest in TBM's.

Too many connection/joints on most models. That is why try to do these with one piece flat sides/top and bottom.

Getting ready to do US Navy planes soon, have an interesting model started, not sure if it will get completed, complex!

Future Models not in any particular order:
Hurricane
Spitfire
FW190
ME109
F4F
F6F
SBD
TBM
Skyraider
Bearcat
Beaver
Piper 140 Cherokee
Cessna 182

Mike

[yukonjohn]

Some options might be to use the Top Flight Jigtime or Keil Kraft sheet models from the Bradley site ( Paul and Ralph Bradley's Model Airplane Hangout - Free Flight Models ) and increase the size of the patterns to whatever span you want. Many, many, many years ago, my first balsa model was a Top Flight Me-109. Seems to me having the canted surfaces on the fuselage instead of just 4-sided box help strengthen the fuselage and keep things better aligned, besides giving a more contoured look.


Keep up the great work,
John

[mbauer]

Originally Posted by yukonjohn

Some options might be to use the Top Flight Jigtime or Keil Kraft sheet models from the Bradley site ( Paul and Ralph Bradley's Model Airplane Hangout - Free Flight Models ) and increase the size of the patterns to whatever span you want. Many, many, many years ago, my first balsa model was a Top Flight Me-109. Seems to me having the canted surfaces on the fuselage instead of just 4-sided box help strengthen the fuselage and keep things better aligned, besides giving a more contoured look.


Keep up the great work,
John

Something to think about for future models. The skin just needs to be strong enough to hold its shape. The loads are carried by the rolled up paper tube through the middle of the fuselage. The wing loads through the balsa box inside the fuselage. Simple but effective structures.

Thanks for the ideas, something to try possibly, will keep them in mind.

Mike

[mbauer]

The 36" wingspan P-40 Fighting Tiger is ready for flight. Weighs in at 9.1 oz. Added 2.1 oz of "lead free" weight to the nose to balance it. High speed test taxi completed yesterday. Swung right due to an issue with a wheel. In case you're wondering Zinc is lead free and about twice the size of lead for the same weight.

Have a few more things to do on the next design. It is a complex model, with a 54" wide wingspan, yes it is designed for rubber band. Happens to be my favorite WWII fighter.

Put it on hold, decided better get some instructions drawn up.

Figuring on listing a couple of the P-40 as complete kits for sale, will include everything to build, so better get going on the instructions. Will be offered as a 36" kit & 22" wingspan kit.

P51 & P47 as well as my RV-6 will be updated to new things learned on the P-40. Lost a little weight. Design changes and then will list them eventually. But, must finish favorite model working on after instructions are done!

54" Wingspan model should have more than enough power to leave the ground! Probably weigh in at 1.5lbs. Wait till you see it, just count the rivets....Who needs panel lines?

Mike

[mbauer]

My favorite fighter from WWII is the current project.

It has taken several weeks to get this far. The build is going slow as well. A few things did not work so well, reprint.

What took the most time? Found a Three Vu drawing on line that had rivets. Talk about allot of rivets. Was able to isolate the rivet layer and then select them, AutoCAD said well in access of 23,000.

Not going to spoil it for you, by giving the actual, just in case you want to count them!

Some things on this very complex build were easy, only pieces of balsa wood for support is the landing gear. Everything else is cardstock. Tail feathers do use carbon fiber for the elevator and balsa wood for the rudder.

Paper tube was enlarged to over 1" I.D. [25.4mm]. Reason you might ask?
on the 48" wingspan RV-6 model, the rubber bands tied themselves into a huge knot that is stuck inside the too small paper tube-going to take some major surgery to fix. Went of 7/8" I.D. to 1.125" I.D..

By making it bigger an issue that I'll soon be facing on the Nacelles to wing connection. Will know by the end of today if needing to re-design and print a fix.

1-Nacelle 90% glued with rubber band tube installed. Will finish last 12" gluing and it will be done. Once dry, will cut out wing opening and see if it fits the wings. If it does, then cut, build and fit the other nacelle in place.

Once both nacelles are in place, will add horizontal stabilizer/elevator and the Vertical stabilizer/rudder.

Once everything is fitted where it needs to go. Will glue all at once to maintain locations.

Final build step will be to add the gear. Weight/balance beginning of flight test.

Canoe Stage with Front Landing Gear Balsa support:


Glue main spar. Using printed pattern on parts sheet. A small piece of clear plastic under glue joint so it doesn't stick to plans:


Marking lines on spar. This is how I align the spar to the fuselage once ready to glue it solid. Waiting until the fuselage is completely glued to glue them, helps to ensure the fuselage is twisted:


Gluing two small 1/8" thick balsa supports to the 1/4" thick main spar connection:




Mike