I Just Broke My Airplane Wing Spar - What I Learned | Scrappy #47

i bent the wingspar machine it draft it build it test it break it not always in that order let's get to work it's physics math and engineering machine it draft it build it test it break it every time something new gets built the entire world advances laying in bed at night it's designing new parts designing new suspension designing new wings hey guys okay i'm excited and super nervous because i'm about to do something that's going to let me know whether or not scrappy is flying this year or next year so go back in time i was designing a wing a long time ago for scrappy and it's a really cool wing and i can't wait to dive into it we're going to dive into the swing spar on this video and we're going to break a wingspar on this video but what had to happen is i had to find a spa that worked for scrappy the loads the weight the g's everything i want scrappy to do and nothing existed anywhere that would work for what i needed and so rather than trying to adapt and add spar doublers and spacers and all kinds of things that still wouldn't get me to the ultimate loads i want for scrappy i had to design and engineer my own wingspar one of a kind and then do an analysis on it to make sure it can handle the load so here's where it gets scary these bars are showing up in a couple of days i just got word they're in route and we got to test them but this is where the rubber meets the road because all the engineering was done in two ways so far one was on paper old school the way i learned a long time ago the next was on solidworks and those tend to agree really close so it's a start unless i screwed up but the real test is how good is modern day analysis fea analysis finite element analysis of saying fea analysis is like saying finite element analysis analysis anyway we need to do a test structural loads poll on a computer and then i had to order that and not be able to test it and then design the entire wing around something i haven't tested and so it made me nervous so i made a mold to extrude hot aluminum our own we have to get aluminum up to 800 degrees optimal is seven to nine hundred at eight hundred degrees we started pushing aluminum through a mold for strap these new spars now what's really cool about extrusion is the metal isn't actually molten it's not a liquid state it's still a solid matter seven to eight hundred degrees it doesn't go into a liquid state where you could pour it until you're upwards of above 1200 degrees so we actually had to push hot aluminum through an extrusion make a spar and since the extrusion companies were way behind because of all kinds of reasons in the world today i'm just barely getting the spars and the entire wing design is done and design free so if this doesn't work i'm host then we'll really have to get back to work so here's what we're gonna do uh they had a minimum order for my spars so i wanted four anyway two for the plane and two for testing um but i ended up with like 30 of them because i had to order a whole pallet so i'll end up making tables and all kinds of other things with the spares but they're showing up i'm a little nervous we're going to test solidworks i hope this is good for you because we're going to find out how is solidworks analysis compared against old school pull it till it breaks and what is the deflection angle and return deflection and return what does the computer say and what does the world would say and when does it deflect and not return to a zero state so these are the tests we're about to do they're showing up i'm gonna start getting stuff ready on the floor and we're gonna break some spars hey guys i guess what we're gonna do today we're gonna break wing spars front rear regular cubs and scrappy's custom spar that was made just for scrappy for the higher load higher g's higher payload i want and the fact that it's a bigger aircraft so i'm super excited because i'm building an entire frame on the floor a jig to bend it and break it and there's some rumors out there about people wanting to do things like remove ribs because they think their fabric is strong enough to be able to remove ribs and span fabric from rib to rib and that that may not have an effect on the spar and it does but i want to test the theory for sure because as soon as you bend a spar when it starts to fail it wants to bow out sideways one way or the other so the ribs aren't just for fabric the ribs are so when you bend a spar it has nowhere to go but one direction and not bulge another so for those of you who've had these campfire conversations about saving weight by pulling ribs let's put this theory to test and see if you actually can or can't but i bought a whole bunch of spars we're going to break them all let's get to work all right got pipes about a quarter inch wall cut a piece of it off weld it on here so there's a big radius then i'll bolt this to the concrete floor this is going to give me a nice rounded edge to bend this the spar against i don't want to have just a sharp point load i won't have something more true to if it were bolted with several bolts and attached so we're just going to give it a little radius edge and pull on it that way so i got to quickly make this bolt the foot floor that works [Music] [Applause] [Music] [Music] [Music] okay for those who want to know the size difference dimensions real quick the rear spar a traditional cub traditional cubs four inches scrappy's rear spar will be five and three quarter inches a traditional cubs main spar five and three quarters scrappy's main spar seven and a half and then the thickness difference about a 0.08 0.08 3 maybe um this will be likely the same nope there we go let's 0.0685 so it looks the same but it's a significant bump up so my rear spar is going to be a lot thicker because i'm moving from 0.685 up to 0825 so quite a jump when we go up to my main spar we jump all the way up to 0.135 so it's a significant amount more material but that gives you an idea all right guys let me show you what i'm doing i'm starting with a rear spar of a traditional cub i've got it right here sitting at 9.5 inches so i'm going to write that right here 9.5 inches as a starting point we'll pull right here i've put these braces on the wall simulating if the spar was inside a rib these spars if i tried to bend it and it wasn't pinched in something as soon as i started to bend it it would just start to bend and then it would bow up and once it did that we wouldn't have any real measurement this mark right here is where it's going to fold against this is at 112 inches representing the connection point of a wing strut now i've kept it away from the wall because as i bend that way simulating the tip of the wing over this point this spar is going to bow towards the wall and if i didn't give it room to actually flex that direction it also wouldn't be as accurate of a representation because that needs to be able to move create the ark and then eventually break so i've got gap so this can bow in and out as needed as it flexes and then this end is just compressed against the wall so it's locked as if it were attached to the airframe airplane wing strut pull cable chain and our load measuring right here so we'll go ahead and crank this now it's not going to take very much weight to bend this so i kind of want to emphasize this is to test how strong a current spar is compared to what scrappy's going to be and a relative load increase i'm going to be able to do on an actual aircraft you build an entire wing for the faa load it up with bags and that load is evenly distributed and that allows the spar to go much further but the fulcrum snapping point is still at the strut if you hit a heavy bump that's where the heavy load is and that's where it will break but in flight it's even load what we want to know is pulling at the weakest link how far till it breaks and what is that percentage to each increase in spar strength so it's a good baseline to check against against the computer see how far we've gone make sure it's going to carry the loads i want which is scrappy anything i can put in the door i want it to fly with a significant margin of safety all right so i just made a quick simple chart cub rear spar traditional cub main spar which is also scrappy's new rear spar and then scrappy's main spar so i'm going to start at 100 pounds and i'm going to write down how many inches of deflection and then we're going to note when it bends and doesn't return to its original state that's its initial fail point might still be flyable if it bent in a big bump to that but then there's gonna be a point when it bends so far or breaks and likelihood likelihood here is it actually won't break it's just gonna keep bending if there's a point we could pull it far enough which we won't do you could actually break it as soon as it bends enough that you wouldn't be able to keep your control surfaces we're going to call that ultimate bail or a break as an ultimate fail let's get out [Music] okay all right so here's the numbers on the first part of catastrophic failure what i'm calling catastrophic failure is one inch it's deflected and this one deflected from nine and a half to eighteen so the spar actually bent uh eight and a half inches and when it returned it stopped at 10.5 and starting point was 9.5 so we're gonna cut that's exactly one inch so we had to bend it eight and a half and it came back within one inch now at that point your wing has literally become a twisted aileron and it's the whole wing tip would be moving and at that point you're going to be hard-pressed to have the aileron have enough control to counteract that much twist in the wing so we're gonna stop the pull right here and call it completely done that was at 250 pounds of pressure at the very end of the rear spar so we're gonna stop here we're going to put in the next bar which is the main spar of a cub which will be the rear spar of scrappy we'll pull it see how much further it goes then we'll do it again with scrappy's new spar so i'm really happy with the results this is very definable usable data actually felt a little lower than i anticipated i thought we could hit uh upwards of 300 pounds and and still be close but 250 we're done let's get back to work i gotta put my glasses on and ron will hit me with them from across the shop [Music] [Music] all right let's see what it returns to all right exactly back to the regime we have no deformation at all yet [Music] [Music] okay i've got little wood paint sticks that are underneath the two by fours to keep it pinched on the spar so it doesn't twist so it acts like it's in the ribs um one of them is slid out i'm going to quickly adjust that but let's check the measurement all right that's definitive now we're a 16th we're 8 and 9 16. so i'm going to say that the last one did move a 16th because this was definitive it moved another 16. so i'm going to put its new point at 8 return deflection 8.67 all that i'm going to put the shims back in let's pull some more this is definitely at a point where if it did abandon just absolute severe turbulence or overloaded in your cub and you bent it you wouldn't even know it there could be cubs flying all over the place like this there is no structural real integrity damage yet just moving that much i mean about an eighth of an inch over that distance is minimal and if you let this sit for a couple days it might relax back in the state so but we're on the edge of going into an actual failed state i would call this you'd never go past this but we're going to keep pulling let's go we want to go tell it goes a full inch and doesn't return i don't know how well my wood's going to hold up trying to get that much tension on it because it's going to take a lot but let's try okay you see the spars ending bending way at the back over there some of the spacing back there is similar to the spacing on a cub as you get further out um that's bar is done we're at 512 pounds let's go ahead and just keep pulling i'm just gonna say what's happening now is i load the weight up and the waist is falling back down this bar is done 500 pounds anything past that now if i wanted this bar to go further i can and that's really simple it's by just tightening up the spacing between the ribs so right now i'm not failing at the bending moment i'm just starting to because we saw an eighth of an inch where it didn't return but we're failing it that there isn't enough side support that keeps the spar from going sideways and kinking there which becomes a catastrophic failure if we want to push this a little further matter of fact i want to i got another spar i'm going to go ahead and add twice as many ribs the equivalent of testing more ribs i'm going to take them and put them down that side which actually would be the correct way to do it because down at that end is closer to the fuselage and that is a little bit tighter so we're going to go ahead and tighten that up and pull it again but if you're wondering why there's so many ribs this is a perfect example so stop that bow out but let's add some more ribs on that end this is going to be a little tighter we're going to pull it to the max and see when the the bending fatigue moment gives completely out with twice as many ribs let's get to work all right we're going to redo the front spar of a cub with the rest of the rib simulation bolted to the wall so we've got the ribs tightened up from 22 inch spacing to 11 inch spacing to see if we can get a better result than this one when it blew out the sides i'm going to go ahead and get my starting measurement 8.5 let's pull it [Music] [Music] now this is the good news guys at 550 pounds the other rib between the ribs completely kinked bowed out the spark came completely unusable and it jumped to a 10 and a half which was let's be clear the tape measure if it says 14 and 7 8 right now let me write that down at 550 it started at 8.5 so i write down on the spar the delta of the tape measure just so you're clear so at this point this bar was done it exploded out the ribs now holding it let's see how far it goes back all right it has deflected an eighth of an inch we're eight and five-eighths look at the difference guys this is how ribs make a difference 550 pounds when we bent at seven and five-eighths it didn't return it was two and an eighth inches bent out of whack and did not go back we're now at 550 pounds it never kicked and it's within an eighth oh and shrinking so starting to relax back so let's keep going see how far it goes for me that tells me everything i need to know for the teeny tiniest fraction of weight each rib saves you you're giving up safety of a king spark and see if we can get it for 600 pounds our 550 600 all right now we've started permanent deformation we are now at eight and three quarters the plane's still flyable so if you saw this wing in flight and you hit severe turbulence and bent it to this point you're absolutely still flying the wings aren't going to crack and come apart but it is deformed and you would want to fix it but we're 100 pounds past the other one and that is coming up on a 20 improvement and we haven't blown the spa out yet all right i'm now lost the structural integrity of the spark so if you look what's happening to this i got it just about to 600 pounds and the more i pull it tightens and then falls back down so i'm going to tighten it some more we are at catastrophic failure right now really cool to see i go tighter and tighter you can see the rib blow out right there between the ribs we're 100 done we got an overall 20 percent gain uh which is a giant number on aircraft guys a twenty percent gain by just leaving in a couple pounds of ribs so i'm gonna call that ultimate fail at six hundred plus as we pass through 600 complete catastrophic catastrophic failure that plane's not flying it's coming out and you better hope you have a brs parachute at that point so because that's a bad day we got one more to pull i'm gonna yank this out of here throwing a scrappy spar i'm super excited to see this number all right guys just pulling this pin out it's kind of fun to see the point at which the spar fail we're doing no damage at the bolt point through the thin spot on the spar but this is an actual normal loading you're actually pulling from one fixed point we'll have a big giant bracket that has multiple bolt points and that i'm not worried about at all every bolt going through it has more shear load capacity than four times the max gross weight of this aircraft and there'll be multiple bolts but it is kind of neat to see that we haven't even deformed the thin metal as we're pulling here and the spar let's go so just kind of fun little things to see the other thing i thought was really cool is if you look right here you might think it would bend here i put the round bar so that i could disperse the load and see where it bent and i'm glad to see it wasn't here even though if it was here we would still have data at what point how much stronger one spar is over another but it's kind of neat to see that it failed elsewhere so let's put in scrappy's one-of-a-kind spar and cross our fingers backwards we're following scrappy's main spar now i'm going to do a starting point right there um nine and three eight let's pull glasses turn to zero when i say return to zero i mean return to the starting point okay let's go to 400 pounds well i went a little don't make a joke about that ah ten and seven eighths [Music] return to zero we have now just equaled the better of the two main spars of a cub test at zero we just did 800 pounds which is double that weight return to zero we have officially doubled the strength of the main spar which has already given scrappy several thousand pounds of payload by the way i'm gonna get excited guys i just hit the target 800 is where i needed to be on this engineer's spar for scrappy i put a little buffer on top of that scrappy's gonna weigh a two thousand pound cub it's a heavy cub most cubs have a two thousand pound gross weight if i go to 4 000 pounds that's double instead of having a thousand pounds of payload i have 2 000 pounds of payload at this point i don't know how i'd ever get it in the plane but that's what i wanted a plane that i can't get enough in it i built the tail to handle it i got a way broader cg envelope and the horsepower to get it off so oh my gosh i'm gonna have a wing because i now already know i'm officially done but let's pull it till it fails i couldn't be happier guys success now let's see how far it will go full return we're at zero we are now going beyond the two thousand pound payload guys as i tighten this up i'm here to go for the thousand mark you can't just increase the spars front and rear which is what i've just done to hit it everything else the brackets the struts the bolts the tie-in the well points you have to chase down every component to its weakest link and on scrappy the weakest link is actually whatever the spar is because all my points my attach points my struts everything is the magnitude of multiple times over the max i'll ever get out of this far so everything has been changed to match it's not just as far so nobody thinks you can just increase the spar and then have the plane fly it so but i'm excited this was a big milestone because it took much to get that aluminum extruded for me and if it didn't pass i'd be starting over with the new extrusion we're past and here comes our thousand ten and three eighths full return to zero i'm gonna sleep good tonight oh my gosh means i'm gonna have some wings the rest of the designs can stay as is now we're just getting stupid because this is crazy we finally bent it a 16th of an inch if we wiggle it it's exactly a sixteenth of an inch i don't know if it would relax back we've officially hit the first onset which would be isn't enough for me to even have a tip like i made on those so we're going to mark that 1 16 of an inch and the best news i got to turn the page i ran out of room let's go for 1200 pounds [Music] [Music] 1500 for 15 and 3 8 and three where it finally hit a quarter inch about 1500 pounds 1600 pounds on the very tip of the wing 15 and three quarters if you look at this right here when we finally hit a quarter inch deflection on this one we are at 550 pounds the quarter inch deflection on this one 1500 pounds almost 300 percent that'll do it we're finally at 3 8 of an inch deflection 1600 pounds let's go for 1700. [Music] it's getting harder to pull [Music] come on break getting tired there it went i think he just went all right it's done come look at this scale fall my scale is falling not going up we officially broke at 675 pounds kink the spar and the weight is falling the other way i just released the tension from the 675 pound max when it bent and let go and started reducing i went down to 11 and 7 8 so if i look at that number off of that nine and [Music] oh yes i can't with my finger it's not that far off of some of the others what's really amazing is that the deflection at ultimate failure as a percentage was pretty much in line it's just the amount of weight it could carry is 300 percent more let's just summarize it 400 pounds it returned to zero on this one we were at zero at 800 which is 200 percent we stayed zero not over failure to over a thousand pounds which is 250 percent of my target which is a thousand pounds above my 2 000 pound payload i wanted it's a 3 000 pound payload with return to zero i don't think i could ever fit 3 000 pounds of payload even with the massive gas tank i have in here to go 10 hours of fuel on board um i can't get it i think i'd have to i need to go to alaska for hunting gold bars let me fill it clear full oh my gosh it's a good day what's fun to think about is how much weight you can hang on the tip of scrappy literally at the tip so if you were worried about whether or not you'd hang your hammock up don't even if it's at the tip not at the wing strut because at the tip of scrappy with a full return to zero no damage to this bar at all i can hang a carbon cub motor and all all three wheels off the ground off each wing tip of scrappy and not hurt the wings cards that doesn't count the additional support of the rear spar that's also a couple hundred percent stronger for my rear spar so i don't see any reason i'd try and hang a cup for my wing tip but i could this is really cool here's some old modeling when we decided to order the spar this is solid works bend testing and then i had a graph i got another graph here the graph that i used to figure out the desired load limits and i overlaid the testing we did on the floor with the original design that we engineered the spar off of and what's really amazing and i'll throw it up on the screen is to look my test shows my ticks kind of go up and down and up and down but they're so close together the computer model and the floor test model are literally within two percent on almost every single one there's a couple outliers one right there one right there and those are when i was ratcheting sometimes i rashed it just a little too far instead of 600 pounds i took it to 625 but it showed every one of those outliners and overlaid on solidworks they chase each other all the way up on all three spars so i'm blown away i mean technology has made designing aircraft so much better so much safer so good job solidworks i am further even more a fan than i already was all right guys i got a crazy idea i was just thinking about what am i going to do with all these bent up spires including the scrappy spa right there and i've really enjoyed playing with these things so i think what i'll do and i hope someone may have interest if not it's i'm going to try it anyway i think it could be fun is i'm going to laser cut all this up into nice rounded clean edge pieces put the scrappy logo across this my name on it maybe i'll uh i'll go ahead and sign the back i don't know if anyone cares but i'll sign in case someone does and then i'm gonna anodize them scrappy colors okay guys i got them all anodized and done orange black silver so this is the set scrappy spar traditional cups bar traditional cub rear spark and then scrappy's rear spar is gonna be a traditional cubs front spar i'm super pumped about i think they turned out really really cool uh unfortunately because i'm not doing mass quantities it costs quite a bit more than i thought to individually waterjet cut a bunch of these and then send them off to anodizers and get them back so um at the best i can sell these for is 50 bucks a set i actually won't make any money on it but i thought some of you might think it'd be fun to have these i'll sign it back i'll put a uh a picture a paper picture or scrap unit or something maybe put the stats of each of the pull tests but it's really just about giving back sharing aviation if for some reason a lot of you bought this little set of three spars of scrappy from me and there was a little bit of money to be made i'll just take that money put it right back into the program of giving away free dracos uh to everybody so i always just want to give it back but it turned out really really cool i really really like it i hope you guys do too this is just a limited thing i only have a few and then when they're gone unless for some reason we got some absurd order uh i could make more but likely they're just gonna be a limited amount and uh when they're done they're done i hope you like it you guys know the drill let's get back to work scrappy's a heavy cub let's make a crazy wing for it i am officially done bending my spar let's get back to work [Music] you

Channel: Mike Patey

Views: 270,265

Rating: 4.9616842 out of 5

Keywords: Air racing, turbulence, Draco, wilga, mike patey, STOL aircraft, Bush Flying, Flying Cowboys, Mark Patey, Mike Patey, Pylon Racing, Patey Twins, Fastest Turbo Prop, Turbine Lancair, Turbine Legacy, Hillside Landing, Crosswind Landings, Water Landings, Water ski airplane, Best tugs, Grip lock ties, Back to work, Carbon Fiber Molds, Carbon fiber layout, how to carbon fiber, custom parts, world record aircraft, experimental, super cub, engineering, how it's made

Id: zcaaznmp4hQ

Length: 36min 24sec (2184 seconds)

Published: Sat May 01 2021