What Happens If You Put A Giant Propeller On A Bike?

before the internet one platform was king and that was the magazine they have pages filled to catch your eye like tools inventions and things to buy they would always educate entertain and inspire all you needed to do was submit your subscription flyer [Music] i have stacks and stacks of all this history so let's open one up and uncover the mystery let's take a look at popular mechanics february 1963. on the cover we got a station wagon with a trailer and an airplane behind it now that is just cool are you the kind of guy who loves to tinker with things yes look at that giant light bulb operating on standard house current 47 300 times brighter than an ordinary bulb believed to be the world's largest the bulb gives enough light for reading 600 yards away whoa what is this submarine built for three skin divers are protected from underwater hazards in a three-man plastic submarine that's neato this is what i came here to see folding wing planes i've always wanted to build my own kit plane my dad is a crop duster so i've grown up around planes my whole life so i'm also interested in flying too marines wheel out two new floating transports now that's cool looking steerable parachute oh that's interesting a little flap over there i've never seen one like that before oh now this is cool looking three dimensions on the double this article talks about a draftsman that can take a 2d drawing and this machine can convert it into 3d even though i have cad this would still be fun to try pick up pedal car for adults i don't know i have to laugh because there's a man in the suit in a pedal car which is generally a child's toy i'd build one to try out what is this a bloated barge looking like a fat jack-o'-lantern a pumped-up bag is actually used by the british military to transport vehicles over water a musical telephone has a swiss music box in a plastic case to entertain collar for three minutes wound by a pulley and a cord it is activated when the handset is placed on the music box cradle here hold on a second let me play you a song while i go to the bathroom it's a good idea at the time we can build a cool toy the little digger that actually would be pretty fun to do but we should do it like man size so it's like all scaled for an adult you just go out there and dig a hole for no reason back seat play room for your volkswagen beetle oh yeah i love the kids no seat belts they're just rolling around in the back seat those are the good old days oh steam engine i've always wanted to build a cool steam engine this one looks kind of interesting oh and good plans too oh look what we got here look at that tiny bicycle he's holding in his hand huh tiny and he's riding it now this is interesting propellered bicycle geared to the regular bicycle pedals an oversized propeller pushes london cyclist around his neighborhood at speeds of up to 20 miles per hour the inventor ernest winter is using his strange craft as an experimental vehicle to test self-propelled flight he estimates he'll need another five miles per hour and wings to get off the ground under his own power he calls his air screw bicycle the glastonbury zodiac winter and other englishmen are competing for a prize offered to the man who can fly a self-propelled aircraft that propeller looks really strange it's extremely large it looks like he built it in his garage i can't see how he drives the propeller his leg is blocking it i'm assuming it's maybe a gearbox or some series of belts my curiosity is raised i would like to try to build ernest's airscrew bicycle i think this would be really fun to try so let's head down to the shop and get started the first thing that i've noticed in ernest photograph is that he's removed the drive chain completely from the rear wheel and only turning the propeller with the pedals i can't tell in the photograph but how does he actually get the propeller to turn and how fast does the propeller spin and what gear ratio did he use i also like to know how am i going to build a propeller that's going to be tricky how much air can the propeller actually push how hard is it to get the bike started on a steep incline what happens if it's really windy can you ride the bike into the wind ernest claims that if this bike hit 25 miles per hour and you put wings on it he can achieve flight he also says that the top speed he's able to achieve is 20 miles per hour so i'd like to try to match that first the only way to get these answers is to actually build ernest bike so let's go do it i'd like to try to replicate ernest's bike as closely as possible so i'm using this my 1974 10 schwinn varsity the schwinn company located in chicago started making the varsity line in 1951. the varsity was a lightweight design weighing in at 38 pounds and the first to feature 10 speeds schwenn dominated the market making dozens of models they mastered the manufacturing of bicycles and coming up with faster ways to weld the frame together as long as bikes have been around people have been trying to make them fly and earnest is no different it's been only recently where people have found success with pedal-powered flight and ernest has helped pave the way through the creation of his machine you got like three feet of air that time can i try it really quick before we start the project i'd like to see how fast the bike can go in its original condition this is going to give us something to compare to when we put the propeller on the back to track the speed and acceleration of the bicycle i'm using a cool gps device called the sky rc it uses the power of satellites to track how fast i went and of course how high i jumped so it's the perfect device to track how fast i go on the bicycle and with the average of the two gps's on my speed runs i came up with 19 miles per hour so now that i know that 20 miles per hour is really fast it makes me a little bit worried about turning a propeller and achieving those speeds the first step i need to do to make this propeller powered is to remove all the original drivetrain components the chain the original sprocket and everything else in between i'm going to keep all the original parts just in case i want to put it back to original but we're not going to need them anymore disconnected oh that's gonna be so weird to try to go with nothing now that everything's disconnected we need to worry about trying to spin the propeller with our feet the first problem is the prop shaft and the pedal shaft are not parallel the second problem is our propeller needs to be up high to clear the ground but our pedals need to be down low for our feet unfortunately i cannot see in the photograph how earnest solved these problems one idea is that he added a gearbox but has its own problems it's gonna add some extra weight it's gonna be a little bit hard to mount to the existing bike frame there's more moving parts and of course finding a location to mount it to to avoid my legs another idea is that we tried to keep it simple and that consists of turning the propeller shaft with two pulleys and one belt the belt is pretty flexible and can be turned 90 degrees i'd like to explore and build this design first because it's much easier to build it may fail but that's okay we didn't put a lot of time into it if it does so i'd like to replace this sprocket with a pulley because this whole mechanism is going to be driven by a belt now this is where it gets tricky i don't know what diameter this pulley needs to be and i cannot see in the picture or the photo how big earnest is i'm cutting this pulley out of three quarters of an inch 6061 solid aluminum i've copied the original sprocket bolt holes that way this pulley should be able to bolt right into its original location so here's the original sprocket with the chain and here's our pulley obviously one is really thin and one is really thick so we're going to have to hybrid both of them what i mean is here's a typical v pulley and i need to copy that profile into the surface but i want it to be close to this thickness to reduce the weight so i'm going to reduce the weight on the inside but keep it fat on the outside and then i made myself this hub so that i can grip on to it with the lathe chuck let's take a look at the pulley for a second the bigger the diameter the faster it spins the propeller so i'm gonna try to target an eight-inch diameter pulley which is the biggest i can fit into the bike frame here's how a v-pulley works a v-pulley is basically a rubber wedge it grips onto the belt from the sides with its 40 degree angle increasing the tension of the belt draws it lower into the v squishing it into the sides creating grip i really need to get the angle correct that way the belt doesn't slip when we go to pedal that looks good the next part we need to build is the propeller drive shaft so looking at ernest's photo it looks like the drive shaft diameter is maybe an inch inch and a quarter three quarters it's really hard to tell the actual drive shaft itself is going to be this 4140 piece of bar stock and why don't i use aluminum well for this exact reason i want to use these sleeve bearings they have a little tiny rollers inside the diameter of this is really small this is a regular ball bearing you can tell the difference in diameter so our drive shaft would need to be giant if we used a ball bearing by using the sleeve bearing we keep it much smaller in diameter the reason why i'm using a hardened shaft is because these needle bearings use the shaft as the race if we were to use an aluminum drive shaft the bearings will just gall and the bearings will get clogged up with filings and just not turn anymore so what i'm going to use to hold the drive shaft is this inch and a quarter aluminum tubing this is going to give the drive shaft the backbone it needs to stay straight and this is going to fit right inside of this tube just like that this requires a half a thousandths press fit so we'll have to turn that on the lathe so this goes inside and then we want the propeller to push on a smooth rotating surface so this is a thrust bearing and it's going to get mounted on the end of the shaft so when the propeller is pushing it has a nice friction free surface to ride on so we'll have to make sure we add that in so we're going to keep this package neat and tidy and as small as possible and we'll recreate this scenario on each end of the drive shaft and then we can get this mounted to the bike got our axle sleeve all bearinged up now i just need to figure out a way to hold it to the bike i need to build a bracket that solves a few problems the shaft is going to be under high stress from the belt tension and pedaling forces so it needs to be able to support the end of the drive shaft to prevent it from bending second it needs to be adjustable for different length belts or for future pulley changes it will also help with belt tensioning and third it must keep the shaft from moving forward and backwards and of course it can't damage the original condition of the bike so welding is definitely out of the question so in order to get started i need to measure the relationship between this upper tube and this main post and i'm going to do it with a level this level has a top secret trick up its leave and it has a built-in protractor inside now i can find the angle between these two tubes flip it over and it's a 71.7 degree angle and that's exactly what i need to take it over to the water jet and get some parts cut i'll leave a link in the description below where you guys can find it so here's our rough bracket shapes that the water jet cut out for us we're going to have to trim them down to make them look good but we also need to find a way to have these brackets grip the tube i have a couple ideas and it's going to require going to the milling machine the bicycle frame is one inch round tubing and i would like a nice good cope to grip around the tube so i'm going to use a one inch ball end mill to make that cope so why is this extra material here this is so that i can put it into the clamp of the vise and get the axes because i'm going to mill a slot right there and now i can put that parallel on the jaws and it sets me up to run a nice straight cut and then we will cut this off afterwards i'm going to set two up at once to achieve a cope i definitely could have used a one inch hole saw but the ball end mill gives me a lot of control on the tolerances which means i can have a little bit smaller so that it really grips onto the tube trimming away that extra material only took a few seconds but man was it handy to have there for the first initial setup the bracket also interferes with the brake cable so i had to make sure to make a slot for that the bracket has a lot of sharp edges and some mill finish that i'd like to remove and blend in so i'm using a ceramic deburring machine and tumbling them for about a half an hour gives me the results i'm looking for well that looks pretty pro now that is just plain cool in order to clamp it to the frame i needed to tap some holes this is going to hold everything securely so check out the mount super strong got the angles correct clears the brake cables but now i need to build a link to tie the tube to the mount using this slot right here that way we can adjust the pulley tension when we go to install the belt so let's go build the link even though this is a little tiny block and looks like a really simple component it's actually really important this is what centers the shaft over the lower pedal pulley front to back and side to side i'm welding it to the aluminum shaft to make sure it doesn't go anywhere i've also installed a spare bearing to keep the tube from deforming when i weld it it will be replaced later so we got everything mounted up front now we need to focus on the back and in earnest his photograph he has a bracket that goes from here down to the center of the wheel and let's recreate that exact same thing because we know it works the challenge with this support is trying to make it look like an original schwinn part i'm using one half solid aluminum round and just bending it in a tight form around the wheel something that looks good the rear wheel axle is a great place to bolt on this bracket it's really going to help keep the wiggle out of the propeller when it's spinning a few good aluminum welds to hold everything secure i definitely feel confident in having the support back here let's do a test with the drive shaft and the pulleys thrust washers on okay let's put the belt on look at that that is so cool we have a shaft coming out the back we have drive so the funnest part about this whole build is building the propeller when i look at ernest's propeller i actually have no idea how heavy it is and it's really hard to tell what material did he end up using is it steel aluminum plastic i have no idea or what pitch angle did he find worked the best ernest's propeller is definitely not flat or i mean constant pitch on a constant pitch prop the blade angle is the same the entire length which would be really easy to make but it sacrifices efficiency earnest propeller is twisted or the technical term is variable pitch this is going to be much harder to duplicate a variable pitch propeller is going to maximize the efficiency of the power source a good way to think about it is that a propeller is a big air scoop and this air scoop puts torque on the shaft the closer to the pivot the more torque you have meaning you can push more air closer to the tip air has the most leverage meaning it should push less air so to maximize the prop performance we need to push more air near the pivot and less air near the tip so let's try to recreate ernest's variable pitch propeller and we're going to start on the water jet taking a look at ernest's propeller again it looks like he used layers of sheet metal but that's probably due to prototyping increasing the propeller size to keep the weight down i'm going to use this 16 gauge aluminum which i think is going to work great i'm also going to try to match the profile and the size of the original as closely as possible all i can do here is estimate if i get it wrong we can try again so here's the part that just came off the water jet and this is going to make up one side of the propeller now this is the closest i can come up with as far as looking at the photograph and copying the design i can tell ernest mounted the propeller to the shaft that's probably about eight to ten inches and this is going to stick out flat now the hard part is how do we curl this big huge flat blade in some sort of spiral shape in order to create the spiral we're going to have to come up with some compound bends and they're going to have to be bent along this grid line it is going to be really challenging to do and then not only to do it once but we got to do it twice but i have one trick up my sleeve this is the beast that's going to help us out this can roll steel 48 inches wide and up to 3 16 of an inch thick so this is not going to be a problem for this thin aluminum i'm using this tool because it can roll cones and how it does that is it tilts this back roller so that it's tight on one end and loose on the other and this is going to give us that gradual bend that we need this would be really hard to do in a press break but i'm going to use it like a press brake so i'm going to try to do this with both of them together so because this corner is the tightest bend it's going to go up tight where these two rollers are the closest and then down here i want the bend to be really gradual and that's going to be the loose end let's start somewhere there and all i'm going to do is raise the roller up by hand if i try to use the power feed that this roller is capable of it would wreck this propeller blade in one second so i have to make sure to do it by hand and go nice and slow also the ends of the propeller blades need to remain flat so i can't roll the whole propeller blade through the roller take a look at that problem number one solved got blades problem number two how do we attach it to the bicycle i want the propeller blades to cross the center line of the shaft so i'm gonna build an attachment hub that gives me that opportunity so we need to create a slot and some way to pinch down onto the blades this hub design is going to allow me to engineer new blades if i need to and just quickly replace them the hub is going to be experiencing a lot of torque so i'm building out of some inch and a half solid aluminum i also want this hub to fit really tight on the shaft that way this is going to reduce the vibration in the propeller i can check the clearance in the hole by using these pin gauges the ground to a specific size to allow me to check the clearance it's a real accurate way to measure the hole oh gosh that's weird [Laughter] i'm at the point in this part where i need to make a really important decision and i could screw it up really fast if i make the wrong choice i would like to have a eighth of an inch wide slot there are several ways i can do this the first one being i could put it in the milling machine and run this slitting saw halfway through flip it over run halfway through it's going to leave me a point in the middle and the back i don't have a large enough diameter to make the whole thing in one pass so that's kind of out of the question the second way to do it is possibly run this through the band saw but it needs to be a little bit wider also the problem with the bandsaw it's going to probably wander and it's not going to be perfectly straight the next solution is take this to the table saw you can cut aluminum with the table saw with a carbide blade but table saws scared me to death and i'm gonna avoid that one like the plague no way dude the next option is to go to the milling machine and run an end mill a tiny end mill down this whole thing with a little whittle the diameter to depth ratio is really bad which definitely means i'm going to be breaking end mills off the last but not least is the water jet i think we can cut the perfect width to length so let's go try that never done this before cutting the slot is actually easy the hardest part is getting it set up to the axes of the machine and i do that just like in any other milling machine where i set up a dial indicator and true in the axes the waterjet will cut anything that goes underneath that nozzle so i'm using a sacrificial v block or a v-pipes to hold it in place yeah baby [Laughter] wow that is a perfect slot thank you waterjet machine you probably can't see it on camera very well but it did a fantastic job we got a nice radius on the inside there that way we won't crack now when you do drill make some bolts to clamp everything together i'm going to be drilling through both sides of this so i just squirted a little bit of hot glue in there to keep it from collapsing and it's really easy to remove later looks square enough for me i probably could have welded these blades to this hub but man it makes me nervous did i get the propeller pitch right so i'm definitely going to be bolting them in place to key the hub to the shaft i'm just going to be using a set screw so i'm going to be drilling a hole into the shaft so that set screw has a nice good mechanical bite to it it also puts the galling from the set screw inside the hole instead of on the ground surface of the shaft thrust bearings set screw got my propeller mount all sorted and machined i'm ready to get the propeller blades mounted up to it so let's do that next i don't know where the blades need to go so i'm just going to wing it somewhere in here we've got this thing all mounted up but look at how wobbly it is super floppy but i got to thinking when i went back and looked at ernest's picture do you remember that sprocket that we saw that looked out of place something looks like this so i think he used the sprocket to tie the wings of the propeller together i made a mock-up version out of some cardboard he basically used the sprocket because it had a hole in it but i don't want to use the sprocket so i made this this is an inspiration on ernest's sprocket this is how we're going to get the rigidity back into the propeller that we need so let's get this installed on the wings it's going to be some rivets and off we go we should be riding this bike here soon look at that we have ourselves a completed propeller it's a little odd looking but i wanted to replicate it as closely as possible to the picture so there's a couple things that i've noticed about it there's going to be some drag in this surface right here it is in the center and this is going to be turning so slow this may not come into effect if it does become a problem i think we can alter it in some ways but i want to test it just like it is the stiffener in the back really did help a lot we have our stub shaft right here and all we got to do is plop this propeller on and if we want to make a change to it we can just pull it off at any time boom that looks amazing since this is a variable pitch propeller i kind of want to give you an idea of how steep an angle it is out here on the tips well let's just grab this stabila protractor kind of give you some idea of the angle i know this isn't the right way to do it but i don't know how to show you on camera so from tip to tip there with it being level it's 60 degrees and of course it's straight here and then it has this scoop to it so ernest in his photograph he has some sort of strut mechanism string or wire that tied the tip to the center of the shaft and i'm guessing that's to keep this wing tip from folding backwards since i formed mine on the roller my wing is pretty stable just in case i need it later i have made these up to add on to the outside and do the same thing but this is just more drag so i'd like to try not to use it if i don't have to but they're ready to go if i need it i should i don't know if this is gonna work this looks ridiculous but ernest knows something that we don't so we have to try it i really wanna see if this big scoop is going to work but it looks good let's get it fastened on here got my trusty hex key holders so here's my predictions on some things that i think are going to go wrong or possibly wrong let me go to test ride it we might run into issues with not being able to turn the propeller fast enough so i have a couple pulleys we don't get the belt speed we're after we can jump down pulley sizes so that's one option the downside to this is that we're gonna probably run into belt slipping issues just because we don't have a lot of surface area anymore i'm pretty confident that this belt will stay on but if it doesn't we'll have to come up with another solution if the belt slips we might have to switch to some sort of cog cogged pulley mechanism so that we get the extra grip we need those are just predictions if i do have to make a pulley change that's going to make my belt length longer or shorter i've thought of that ahead of time and added this slot into the mount so it's an easy adjustment when we're out there trying to do our testing the next thing i'm worried about is the propeller tip getting damaged if the bike gets tipped over or falls down hits the ground as the bike leans let's check out the clearance on the ground i was trying to target around three inches and i looks like i did that so before we take this bicycle on the test ride let's do a little shop science and test the performance of this propeller let's have a little competition let's test ernest's propeller up against a large commercial fan the fan we're going to be using has four blades with a diameter of 42 inches it has a 2 horsepower motor capable of spinning the blades up to 1750 rpm but has constant pitch blades for easy manufacturing it also has a shroud to funnel the air making it more efficient i'm going to be testing the fan in three locations the first one is going to be at two feet and it generated 11.4 miles per hour the second is at six feet and it did 8.9 miles per hour and at 12 feet it did 7.8 miles per hour that's the benchmark let's see ernest's propeller and see how it does all right let's give this bike its first shakedown test oh it's working feels good the belt's not slipping the pedaling feels just like it would with the wheel feels like i'm stuck in 10th gear so i'm gonna pedal my hardest and we'll capture what the fan speed is at two feet it did 15.2 miles per hour at six feet it did 17.2 miles per hour that's incredible and at 12 feet it did 8.3 that is pretty good now that we know what the wind speed is let's actually take a look at how the air moves so let's set the smoke machines up and test them the fan looks like it's really moving a lot of air and it's pretty cool to see the smoke get attracted to the center of the fan the airstream looks really smooth and controlled that's probably due to the fan shroud now that i've seen the fan in action let's take a closer look at the bike propeller i'm going to try pedaling as fast as i can i want to recreate that 17 mile per hour wind speed i have to see this again so let's look at it in slow motion for such a slow spinning propeller it looks pretty effective it's pretty cool to watch the propeller take big gulps of air and throw it out the back you can see the smoke doing a helical twist no wonder why ernest called this the air screw bicycle comparing this propeller to the commercial fan the air coming off of this looks a lot more violent and a little bit more turbulent overall i'm pretty impressed with the performance of this propeller and i still can't imagine that this was a piece of sheet metal here in the shop feeling a little bit more confident about the propeller there's only one thing left to do and that's to take this bike on a ride i want to do some practice writing to get the feel of it and sort out any issues that i might have before i tried the 20 mile per hour speed run but it's the moment i've been waiting for okay prepare to laugh some of the things i'm noticing when riding the bike getting the bike started is probably the hardest you kind of have to kick off like you're riding a skateboard then you have to pedal really fast to get going it's a really weird feeling to have to pedal so hard without going very far it's really strange to have one speed and it feels like you're in 10th gear on the normal 10 speed bike even at maximum speed the propeller is virtually silent also the belt did stay on the pulley the entire time and never really did slip i also thought that the drive shaft would be in my way when i pedaled but i completely forgot it was even there all the brackets and supports we made seemed to keep the propeller in place and never moved at all as you can see accelerating isn't this bike's strength but once it gets up to speed it really does start moving naturally a propeller powered bicycle is going to attract some attention so of course what do you do you have a race this is a perfect time to test out acceleration compared to a normal bicycle [Applause] oh well that was so weird a lot of work for not going very fast but i wasn't trying to go my hardest try to save my strength here but let me catch my breath and we'll go for the speed run while i catch my breath and prepare for the 20 mile per hour run let's talk about the road conditions this is a chip sealed road with some coarse rocks with a sustained wind from two to three miles per hour just something to take into consideration but nothing really to worry about i have the need the need for speed let's go okay no laughing oh we're going holy moly that was fun let's see what my top speed was 17 that's pretty dang good which was exactly the airspeed of the prop 17 miles per hour just ain't gonna cut it so i think we need a rider mod this is jackson and he's our best bet to get this bike up to 20 miles per hour he's been bike racing for eight years and is one of the top rated riders in the region and recently winning several local bike races jackson's used to riding a 18 and a half pound lightweight racing bike equipped with clip-in pedals and a rigid carbon fiber frame it's way more advanced than the 1974 varsity whoa wow oh she weighs quite a bit doesn't she to see if this thing can actually do 20 miles per hour i think you are going to be our best bet to achieve that number well i will i'll definitely try my best on this before he did the speed run jackson wanted to try it out to see how it rode this is uh you know definitely nothing like i've ever been on before wow it's really hard to keep in a straight line whoa it's uh not the most aerodynamic thing yeah i'm getting my warm-up that's for sure there we go getting the hang of it a bit yeah what i first like really felt like was it kind of felt like uh like riding through sand okay it's like an unkin like the front end is like a little wobbly yeah but the back end it just feels like you're you can just put as much power down as you possibly want and you're just staying in one spot riding in sand that is a great description of what it's like to ride this it's an interesting interesting thing you have here now that jackson was feeling confident on the bike all right i asked him to try to start on a hill wow yeah it takes a little bit to get her going definitely a tough one yeah without any success on starting on a hill i asked him to try to ride into the wind and see how fast he could go i'm gonna predict your mate get five i'll try my best okay that was a 10 mile per hour gust but it's hovering around 2.5 [Music] oh that might be it it looks like the fastest jackson got up to was six miles per hour into the wind but 6 miles per hour is actually pretty good after he caught his breath it's now time to see if he could reach earnest's claim of 20 miles per hour [Music] so let's check the speed of jackson's run what do you think about that number pretty i'm pretty pleased with that one 20 miles per hour that's pretty impressive seeing jackson hit 20 miles per hour makes me want to build a bicycle to go faster how cool would it be to build a world record-setting propeller bicycle and try to hit 25 or even higher with modern technology a carbon fiber bicycle and all the trick gadgets thrown at it i'll leave you with a video that i found after i built the bicycle of ernest actually riding his bicycle how cool is this ernie winter reckons he's hit on the last thing in cycling let the pedals drive a propeller not the wheels and he expects to go so fast he'll have to be careful not to take off in healing the nearest they allow to aviation is flights of fancy so far ernie isn't quite satisfied with the screw and his best speed is no more than 20 miles an hour but never mind the first airplane didn't fly the atlantic did it so if you see something strange overhead someday it may easily be ernie [Applause] [Music] [Applause] [Music]

Channel: Fireball Tool

Views: 5,153,334

Keywords: fireball, tool, Fireball tool, Welding, Popular Mechanics, propeller bicycle, Custom propeller, Schwinn, Vintage bike, Bike mods, Air tunnel, Strongway fan, Flying bicycle, Wind powered bike, 1978 schwinn, Austin Powers, Dude Lebowski, Packfiller Productions, Waterjet, Aluminum prop, Pulley, DIY, Lathe, Milling Machine, 1963, Parachute, Volkswagen, Giant lightbulb, Phone music box

Id: a5gbT7Uo5qY

Length: 34min 58sec (2098 seconds)

Published: Sat Apr 30 2022

Reddit Comments

[u/w4laf]

My legs hurt just from watching!

[u/turbofeedus]

Awesome video, but I'm not surprised at the result. The chain-gear driven bicycle is a remarkably efficient vehicle. In fact, it's the most one of the most efficient ways to move a human over any appreciable distance in terms of total energy spent, generally only edged out now by modern electric single rider vehicles, and electric trains. Then next most efficient method is just walking. https://en.wikipedia.org/wiki/Energy_efficiency_in_transport

[u/GlockAF]

Human beings don’t generate very much in the way of horsepower. From Wikipedia:

“When considering human-powered equipment, a healthy human can produce about 1.2 hp (0.89 kW) briefly (see orders of magnitude) and sustain about 0.1 hp (0.075 kW) indefinitely; trained athletes can manage up to about 2.5 hp (1.9 kW) briefly and 0.35 hp (0.26 kW) for a period of several hours.”

The subject of human powered propellers has actually been studied with a surprising amount of rigor, due to the numerous attempts over the years to produce human powered aircraft. At least one guy actually did his thesis on it

https://honors.libraries.psu.edu/catalog/21582

If you want to look at what I really efficient human powered propeller looks like, check out photographs of the record breaking & award-winning winning Gossamer Albatross human powered aircraft from 1979. It’s quite likely that the optimum diameter for a human powered aircraft propeller is much larger than is practical for a bicycle

https://en.m.wikipedia.org/wiki/MacCready_Gossamer_Albatross

[u/3L54]

This guys videos are always very enjoyable.

[u/copperwatt]

That was an unexpected gem!

[u/nuke-from-orbit]

I enjoyed this video a lot

[u/_todash_]

I had a small panic attack when the dog showed up.

[u/Glittering-Animator2]

Dog got pretty close to the propellers lol.

[u/CarnivorousDesigner]

Oh man, this was awesome. Thanks!