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Fullfilling the dream... the ultimate rubber powered airplane

FAI-F1D

Free Flight Indoorist
#1
I grew up in a rather unique environment for aviation. My first models were paper planes, which Mom taught me to make at age 2 and instantly regretted it. My dad held a private pilot's license, and Grandpa got (and used) his commercial on his GI bill in 1946. I was doomed from the start to live an aviation lifestyle, and this was only boosted by my dad's work to get his Instrument rating when I was 5 years old and the occasional slot together rubber band planes from Grandpa.
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Dad introduced me to rocketry when I was 8 years old and the law of unintended consequences kicked in. I wanted to do the thing he'd never been able to figure out--put wings on them. To his alarm I was successful enough on my first try to completely fill my room with boost gliders in under a year.
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I was 12 years old and my obsession with learning more about these machines let me across the internet where I stumbled upon Bill Kuhl's first website which described his Tweety Bird rubber powered flying wing which was giving him roughly a minute indoors. I couldn't believe a rubber powered model could fly that long and had to know more. It was then that I learned about something my brain simply couldn't process. Only two years prior, some guy named Steve Brown had gotten a rubber powered model to fly for ONE HOUR in a hangar in California. HOW??? How could he do that? How could anyone build a 40" airplane to barely over 1 gram? How could a propeller taking almost 2 seconds per rotation keep an airplane in the air?
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I spent the next 13 years flying stick and tissue rubber models in contests all around the country. I would occasionally dabble in indoor across those years spanning high school and college, but though I could make a decent indoor model, I just gave up on the idea of building a one hour model since outdoor was what I was good at. All that changed in 2010 when I flew my Spruce Goose to a national championship win and realized I'd taken free flight scale as far as I could ever go with it. Something had to change.
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In January 2011 I built my first F1D using parts I'd originally cut out a decade prior.
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It flew well enough that I built another. And another. And another...
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From 2011 to 2014 I spent literally thousands of hours building and flying F1D models to chase an elusive and seemingly impossible F1D national record, all the while working on my Ph.D. during daylight hours. I lost a lot of sleep. I got married and it got worse, but at least I had someone willing to do this crazy flying with me.
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Contest after contest saw me return home disgusted with my inability to get anything more out of the planes, and contest after contest saw me show up with a new plane which occasionally boosted my best time closer to the record. Finally in late 2013 I had a series of test flights which conclusively proved I had a record capable airplane. We finally made it to a contest in February 2014 where I slid right past the record after only one failed attempt. I had done it!
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And just like that the FAI changed the rules and stripped it all away. Oh well...managed to adapt set other records, the rest is history.
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Now on to the relevant bit. After setting the impossible record, my flying buddy, Nick Ray, convinced me that anyone who could break that record could also break the then 18 year old Cat I Unlimited endurance record of 39:19. Yes, that's almost 40 minutes. In a gynamsium. With a rubber band. And no radio. And no thermals.

Nick built a plane in August 2014 and it flew well, but blew up during a flying session at Lakehurst.
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Using his lessons learned, I built my own in late January 2015 and dabbled with it for the next three years, flying it to first place at the 2016 US Nats with a flight in the mid 20's and first place again at the 2017 Nats with a 31 minute flight, my first time ever to slide past half an hour with a rubber model.
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I concluded that the insane unbraced wing just wasn't going to cut it and decided to build a big braced wing and a monster 25.5" prop. By November of last year this insane machine achieved 34:25 in our gymnasium flying site, less than 5 minutes off the record. I'm continuing to update this model. And that's why this thread exists. I want to break that record and then take the hour record--a feat only two people have ever achieved for a total of only three flights over the hour mark.
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When I told Josh Bixler I was going for the hour mark, he told me it was time to tell the community about it. So here we are.

Several things are happening in this thread:

1. I'm going to build a larger horizontal stab for my Hourglass II Unlimited model.
2. I'm going to make a kit for it, and Hope is going to build one. I'll sell the other one to an undisclosed customer who has been wanting this thing for a long time.
3. I'm going to render Hourglass II hopelessly obsolete by building an indoor model at a scale that will completely change the standard for indoor flight performance. Well, that's what I keep telling myself. It's going to be crazy as it is. I've already spent $200 on covering materials alone.

There are major challenges associated with a big indoor model. Steve Brown told me his Time Traveler record model was constantly breaking and needing repairs (remember, this thing weighed only 1.1g, scarcely more than a paperclip). In the tradition of ultimate performance indoor models, he covered it with microfilm, he only thing that was available for that type of flying back then. It was so fragile that it was destroyed before he ever took a photo of it. Jim Richmond's Starwalker which achieved 59:59 suffered the same problems. Wondering what microfilm is? Check out the sheer insanity of it here:
Yes, really. Anywhere you touch microfilm, you WILL leave a hole in it. No joke.

This difficulty has let to an apparent physical law that no microfilm model over 40" span has ever set a record. They're too unwieldy. Too fragile. Don Sluzarczyk's 40"+ microfilm model actually caught on fire during repairs at the 2013 Nats. Similarly though, the events leading up to that fire were a hang up and subsequent crash involving substantial damage. Take a look: https://indoornewsandviews.com/2013/08/14/2013-usic-reporting-by-mike-kirda/
Max Zaluska came within 70 seconds of the hour mark in 2015 with a plastic covered model but it was destroyed when he tried to get it loose from the ceiling on a hang up.
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John Kagan did achieve 61 minutes with a plastic covered model about 12 years ago, proving the advantages of that material.
 
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foamtest

Toothpick glider kid
#3
Wow, that's a lot of history there. I have always been interested in this but I know that I will never have the time or the patience to build one of these. Good luck on breaking the record!
 

FAI-F1D

Free Flight Indoorist
#4
Wow, that's a lot of history there. I have always been interested in this but I know that I will never have the time or the patience to build one of these. Good luck on breaking the record!
Don't think it's so hard as you might think. There are lots of easy kits out there like the ones from lasercutplanes.com, and after you build a few it starts getting easier. Obviously Unlimited is just that and it's totally insane, and F1D isn't far behind thanks to its status as a world championship event. Most of the others are traditional ultralight balsa models that are decently accessible with some practice. You really should give it a shot. :)

You're even crazier than I thought! This will be aweseome! :applause:
Yup, that's me. I don't place much credence in sanity. :cool:
 

PsyBorg

Fly Angry
Mentor
#5
hehe what do you do? Toss it in the air then go out for a three drink lunch and come back to catch it? :p An hour is a seriously long flight. That is incredible. Hope your camera man likes NASCAR... Left turn....nother left turn... Ohh LOOK!! nother left turn!!! It goes roundy roundy roundy.

My hands are wayyyy to spastic to even think about a build like that. You have to be rock solid to work with things that fragile I am guessing. Like sniper level control your breathing type solid, or better yer surgeon level stable.
 

foamtest

Toothpick glider kid
#6
I prefer airplanes that I can design, and make, within a few hours and be able to do stupid stuff with and have it keep on flying. (that's why I have been obsessed with FB micros recently)

But I love planes like this I just don't have the patience for them, maybe sometime in the future when I have more free time (AKA when I retire)
 
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SlingShot

Maneuvering With Purpose
#7
It's that kind if push from within that gets things done. Very cool!

What precisely is the limiting factor? Conceptually it looks like the whole strength vs. weight vs. size conundrum. But is there one single element?
 
#8
When I saw the FT video featuring your work, you came across as a sensible guy with a lot of knowledge about an obscure but terribly interesting niche of the hobby. Now, reading this thread, I believe you're more of a crazed, driven genius, muttering and cackling as you design in some laboratory of avionic horrors. Which is to say, it's inspiring as hell. :p Before, I was content to just do a little research and be impressed by rubber models. After this, though, I'm eyeballing the possibility of jumping in myself, just to see if I can do it.
 

FAI-F1D

Free Flight Indoorist
#9
Before, I was content to just do a little research and be impressed by rubber models. After this, though, I'm eyeballing the possibility of jumping in myself, just to see if I can do it.
THIS.

This is why I do this stuff. Let me know of anything I can do to help you get started. :)
 

Daniel Kezar

Ultimate Cheap Skate
#10
When I saw the FT video featuring your work, you came across as a sensible guy with a lot of knowledge about an obscure but terribly interesting niche of the hobby. Now, reading this thread, I believe you're more of a crazed, driven genius, muttering and cackling as you design in some laboratory of avionic horrors. Which is to say, it's inspiring as hell. :p Before, I was content to just do a little research and be impressed by rubber models. After this, though, I'm eyeballing the possibility of jumping in myself, just to see if I can do it.
haha yes! i watched that ft video at least 4 times. it was so incredible! i was into balsa gliders all my childhood and this dude made them way cooler than the guillows 10 piece throw-it-together stuff i was used to!
 

earthsciteach

Moderator
Moderator
#11
Josh Finn is one of my heroes. I've dabbled enough in endurance flight through coaching Science Olympiad to get an idea of how minute the changes are that, together, add up to a huge difference in flight time. I can't imagine what its like to compete on a national and world level with this stuff! Part of me so wants to go down that rabbit hole, but it has to be so all consuming for years to gain the knowledge that is needed. Just, wow!
 

FAI-F1D

Free Flight Indoorist
#13
Alright, let's get started.

I've been working on drafting this rascal up. Several changes have been implemented. I straightened the wing spars so that I've got constant chord all the way to the wingtips. This bumps the wing area up by about 10 sq in, probably a negligible effect, but it simplifies things a little. Maybe. Who knows...

The stab is also stretched from a hair over 22" span to 24", and the tips are fattened so that I get a little more area back there. Hopefully that'll help with stability. Also, I moved the wing back .75" to get a tab more stability yet. Hopefully these two changes will make it a really easy flying airplane at full torque. I plan to modify my own model to reflect these changes because its quirky habits are the inspiration for these updates.
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The stab and wing templates are fairly conventionally. The tip cuts are a bit of an issue and I may modify these templates to address the need for compression ribs. I've got a plan for making that happen--it's pretty simple but hard to describe.
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These templates are much too large for my laser cutter, so they'll be broken up as follows:
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A massive, super light wing like this one requires wire bracing. And here's the template for making a bracing jig. If this looks weird and unfamiliar, that's ok, you'll understand later. ;)
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The wing ribs are very critical on models of this type. I'm working on trying to laser cut the ribs. A few extra ribs are included in these sets because people typically do break a rib or two in the build process. My kit will actually include enough parts to build two airplanes, and will have four sets of ribs just as a safety margin. Notice that even the entire compression ribs are included, and they carry the stubs for bracing anchors. This area still needs a little work, but I need to work on troubleshooting the actual active cutting these with a laser first. These are very, very thin parts cut from crazy light wood.
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Here's a look at the laser cutting file for the ribs:
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More later...those fuselage blank templates are going to be a riot.
 

FAI-F1D

Free Flight Indoorist
#17
I was really concerned about getting a successful cut on such thin wood. No issues whatseover. I soaked the wood down and cut it while wet. Perfect quality.

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