Massive 16 Foot Rubber Band Powered Airplane

oh for Max wines 150. here is a guy winding the propeller moments before attempting to fly the world's largest rubber band powered airplane with a 16 foot wingspan it is virtually identical in size to this human carrying airplane called the cree Cree and 2.9 times larger than the smallest human carrying airplane ever to fly the star Bumblebee 2. as a kid growing up there's a good chance you had something like this it was a simple rubber band powered toy but it transported your mind into the skies or just frustrated you while trying to keep it in the air either way the idea here was simply to see how large I could make one since I was at it why not just try to make it the largest free flight model in the world I have been reduced to a one rubber band plane garage this project seems straightforward enough when I decided to go for it little did I know when I started this project seven months ago that this would turn into the most frustrating and time-consuming video I had yet attempted rubber band powered models had a significant role in setting the course of history as far as we know the first heavier than air Contraption to ever fly was a rubber band powered model called the plano4 first flown in 1871. seven years later the Wright brothers got a hold of a rubber band powered model the obsession with flight set in and the rest is history foreign these simple models have sparked the interest in aviation for countless kids both young and old the thought was to scale this model up and construct it just like the original now making this out of solid balls of wood wasn't going to work as that would break this Channel's budget for the next 10 years also wood prices are very high right now due to its extensive use in modern windmill blade construction however my local hardware store has these eight foot sheets of very lightweight insulation foam at a fraction of the price now an eight foot wingspan would not break project Air's recent world record of 11 feet but two sheets would and that is how the wingspan came to be 16 feet the thought process he's guiding this channel can get quite deep even though this model is larger than some manned aircraft 16 feet is still pretty small for an airplane in general why don't we see larger rubber band airplanes a big part of the answer has to do with surface area if you double the size of a rubber band the surface area and power does not double it actually goes up by the square this is great news until you learn that the volume and thus weight increased by the cube all those gasoline-powered aircraft you see do not share this problem as the fuel is consumed during use and thus its energy also increases by the cube not the square this is why you'll never see a rubber band powered airliner this was also the reason I was worried just scaling this childhood toy up directly would not work nevertheless I set out to see what would happen I figured finding quality rubber for powering this airplane would be the main showstopper but it turns out that spear fishing rubber in lengths of many feet was readily available so the build got started while the insulation foam I used for the structure is probably as light as any Balsa would I would be able to get a hold of it is also quite floppy and would need a dial to keep it from bending as well as a fiberglass skin to keep it from twisting since this was a solid structure just like the child's toy airplane my volume was rapidly increasing and so was the weight much more than the giant rubber band might be able to handle this project was a great way to make use of 3D printing it made replicating the plastic parts on the original very easy especially since the Buddy quickly catted them up to save me some time you rock man go with three rubber bands on there when they started spinning it just melted the 3D printed pla after adding a Thrust bearing between the propeller and mount I painted the plane to make it look like it should and headed out to the Flying Field so hopefully the wind will switch and we can roll it off the hill up there yeah really well done the all-important center of gravity was checked one more time before heading out into the field for the maiden flight the sheet of plywood acted as a barrier in case anything let go under the tension of a fully wound rubber band this is the very first try and decided to head my way engine on it snapping all right here it doesn't go three two one I gotta have a Thruster bearing on there but it needs like bearings on the shaft too so we don't waste the wine are you gonna run it down the hill this result was mostly due to the weight of the model with rubber bands loaded the contraption weighed 27 pounds this is way too much for these rubber bands even if the wings had real airfoils in the propeller and drivetrain had been optimized because of this I had brought the plane to this particular location in case I needed to use the hill behind us I wanted to see if it could at least Glide [Laughter] that flight completely exceeded my expectations also I'd like to thank Noel I'd never met him and hadn't expected anyone else to be at the field that morning but he turned out to be instrumental in getting that flighted windy the wind picking up the propeller broken and no hope of this flying under its own power anyway there was nothing left to do but send it on one final mission building it but I'd become convinced quite early in the bill that this was not going to fly under its own power I was excited to move on to version two which I felt with a few key changes would be able to fly under its own power the biggest change to be made of course was to bring the weight of the aircraft down nearly all real airplanes are mostly empty space so that the volume cubed rule we talked about earlier doesn't turn them into lead sleds the rule applies not only to the power source in this case a rubber band which I cannot do anything about but also the airframe which I can do something about there are rubber band powered planes so lightweight that they can only be flown indoors yes this gentleman really is moving that slowly so as not to break the model that is a bit too fragile for an outdoor model but I wanted to demonstrate the effect of extreme weight reduction on performance as this can fly for over half an hour as well as point out that his company actually saved this project later in the video linked to his company in the description instead I drew my inspiration from human-powered airplanes they are the right analog as they survive outdoors with a heavy human payload while remaining lightweight and flying on minimal power they also use real airfoils which generate more lift and less drag than the flat plate Wing from this first model this is important as it allows the airplane to lift the same weight using less power since we are using a weak rubber band this is exactly what we want as I was no longer copying the toy airplane directly I laid out the new wing and tail in my computer so that it had a better chance of flying the first time instead of me just guessing I created a one-fifth scale Chuck model of what I had drawn up in the computer to see if the computer was telling the truth it was good enough for me so I started building the 16 foot version too I needed thin sheets of foam to create all the flying surface airfoil shapes my local aircraft supply store had this cool Balsa colored foam that kept the Vintage feel of this project intact also this channel may be doing things wrong I've been using Aerospace grade materials for my models and Home Improvement store materials for my manned projects something for me to think about foreign [Music] that is mostly empty space a lot of trusses actually this model is essentially a lot of little truss bridges covered in a thin bag The Spar that keeps the wing from bending has a strip of carbon on the top and the bottom a piece of foam is placed in between to hold them in place and then thin fiberglass gets epoxied in place with fibers running at Angles to create the trusses each Wing rib is the same except the carbon strips are thinner and conform to the shape of the airfoil then you just need a Leading Edge and a trailing Edge made out of lightweight carbon cover that all in plastic and you're done except here the project started to go sideways very quickly here the covering is on shrunk and then as I Shrunk the covering the rib is bowing and bending as is the trailing Edge so the covering is shrinking too hard it's too strong I got to figure out something else this project has taken up quite a bit of time at this point so to save the time shipping would take I just drove the few hours to my carbon provider to get what I needed for my first attempt at a solution the first solution was to brace the ribs with these tiny carbon rods and covering was again applied that seemed to fix the rib bowing on the next cover but the trailing Edge was still too weak so the covering came off and the trailing Edge was reinforced with more carbon this is the third attempt at covering it takes about six to seven hours to get to this point each time hopefully the third time's a charm [Applause] it wasn't a charm there as after sitting for several days the ribs began bowing again under the strain of the covering I'm gonna be covering the wing for the fourth time this was where the previous gentleman saved the project I was only able to find one other source of lightweight covering at his store it was three times thinner than the covering I was using and ended up being absolutely perfect the project could move forward again the tail pieces were constructed in the same manner except they could be adjusted on the ground to trim the plane if needed after each flight yeah not a chance so kind of have a big problem here this is one quarter of the fuselage this is just one wall and it basically eats up the entire weight budget so it was back to the carbon supplier for the material to make the body into an open truss structure oh wow still pretty heavy hopefully I won't use all of it I did end up using a bit more than I wanted to and the wings were also a tad heavier than I had intended so I was a bit nervous as to how that would turn out making the propeller was the other major consideration as obviously I couldn't just go out and buy one the first prop was meant to look like the original but was far from ideal aerodynamically my friend Austin generated a spreadsheet for me to get the twist in the prop correct or at least make it a good guess with the limited information I could provide him because the tip of the propeller is moving in a circular Direction much faster than the root of the propeller the propeller needs to be twisted along its length for all parts of the blade to meet the air at approximately the same angle as the propeller moves forward through the air getting the twist wrong like on my first hand-shaped propeller wastes a lot of power power we cannot afford to give up the foam propeller was placed in a jig and then the twist was locked in place with fiberglass it was tedious but I had to get everything as close to perfect as I went if I wanted this to fly the propeller received some paint to make it look official the nose assembly was then put together and I had my first chance to see everything in action it pulls pretty hard guys 150 wines two strands the weather forecast for the next day wasn't ideal but it was the only possibility in the 10-day forecast so it was go time turns out I couldn't even wait till the next day to get some air under the wings [Music] the wind out in the desert was not ideal with gusts of even a few miles per hour able to really upset the plane [Music] but there was a good possibility I wouldn't be able to complete this project for another month if I passed on that day's opportunity so I decided to at least give it a chance to start things off I did not wind the propeller I just wanted to get an idea as to whether or not the all-important center of gravity was acceptable and if the starting trim on the tail was okay nothing seemed catastrophically wrong so I went for a test hop with half of the wines that I had tried at home in the shop [Music] the initial powered flight was really promising so for the next flights I decided to go with 75 power heavy wind with more power though the plane was not interested in climbing I added a tiny camera in the tail to shift the weight back added a little elevator trim and Let It Go Again wow [Music] wow I was pretty happy the hard work might be paying off so what would happen if I gave it its maximum power the winds had not become any worse and it was time to find out like another flight we're familiar with this one lasted 12 seconds it certainly didn't set any endurance records but it's a good starting place if you're more of a builder or if you just want to support the channel feel free to check out my patreon page and become a supporter I've posted a long form video detailing the build of this aircraft if you enjoyed that video you may enjoy one of these popping up on the screen see you next time

Channel: Think Flight

Views: 966,553

Keywords:

Id: jgwkA-hLvf4

Length: 14min 3sec (843 seconds)

Published: Tue Jun 06 2023