2021 Virtual Spaceport America Cup - BurnSim for SRAD Solid Motor Simulation

the winner says okay it says broadcaster started so i guess i'm here um all right so uh uh my name is greg deputy just in the way of quick introduction uh uh i guess i'm here because i'm the author of burdensome um in way of personal introduction i was uh in about in the i graduated from high school and went to byu studying chemical engineering with the intention of uh getting into uh the propulsion field um actually ended up dropping out and getting pulled into an it uh it career which is what i'm still doing today so i ended up doing um propulsion and rocketry as a hobby um and i uh burns him it's a program that i wrote in my spare time it's still something i maintain my on my own uh started way back well year 2000 is when i when it first came out it was a program known as it first was called k inculator or kn calculator um for those of us that are uh k n was kind of or using kn to develop motors way back in the early 2000s was kind of the norm for tripoli and people doing research motors and so that was kind of the first tool that i came up with for simulating where those curves would end up so people could build motors that would blow up left less often and that eventually developed into burn sim which uh took it beyond just simulating the cayenne which is the ratio of propellant surface area to nozzle throat area over time um i'll do a quick walkthrough i don't know i have no idea what uh how many people uh who are attending today have used burn simmer been exposed to it but give a let me share share screen and do a quick walk through let me see there we go of so this is burn sim uh it's a few areas here to walk through how it works and what you what uh what's important uh it starts out over in this area here i hope you can see my mouse moving where you define the different grains of propellant that you have there's a few details over on the upper right here for nozzle your propellants and there's actually a startup tab here which isn't currently enabled this is some some stuff i was playing around with to simulate startup transients and that sort of thing but very basically if you want to simulate a rocket a rocket motor in burn sim obviously the most important thing is to get accurate results is to have a characterized propellant if you don't have that there are well you're going to yeah there's the two default propellants that come with burn sim called slow and viper um they're uh just a couple of pretty vanilla ammonium perchlorate propellants uh the important numbers um when you're simple when you're when you're putting in a propellant and your well your characterization numbers that really matter are number one the burn rate coefficient burn rate exponent and those are pieces of the burn rate formula actually i can throw that up really quick here too if it'll let me um i'm just going to switch to sharing my whole screen so i can see so you guys can see everything i'm doing share screen share my entire screen there we go so i see myself okay so jumping over here this is kind of the core of what burn sim does um using the burn rate formula to calculate how how fast profile is burning and all that is this is kind of a simplified formula but all it is is the burn rate coefficient times the chamber pressure to the burn rate exponent and all burn sim does is when you design them let's go back here real quick so we can just see okay i'm going to add a propellant i'm just going to choose choose a propellant and i'm going to do a small like a 29 millimeter motor or thereabouts actually we'll just say pick a random grain length of three inches one inch diameter with a quarter inch quarter inch core oh i'm sorry here we go quarter inch core one inch diameter uh no ends inhibited so this is just a typical bait strains other grains are available uh base screen is obviously the most common but there's a lot of other things that people mess with in here and you just add a grain and let's say there's two grains and this just kind of gives you a 2d representation of the cross section of the grain pick a nozzle size we're going to say you know just nozzle diameter 0.2 minute 22 inches exit diameter is going to be a little bit bigger just say one and you just start getting data and what you're seeing over here is i'll turn these all off and then just put them back on one at a time this again as you can which was the beginning of the whole program which is you know your ratio of propellant surface area to the throat area and the reason that's an important number it's an easy way to keep your to define where a propellant is going to basically work in a motor if you keeping you know you you can without having to go through the hassle of characterization it used to you you'd um mix up a propellant you tested motor if it didn't blow up you were happy and you could figure out oh the k n maxed out it you know in this case our maximum can was you know 450. so typically you can say okay this propellant ran at 450 it didn't didn't rupture the case as long as i designed other motors to keep the k n under that i'm good to go and then later on we wanted more than just doing the kn so it's added thing you know where we can simulate the pressure which in this case you know we're heading up heading up around 100 psi which is you know for for a smallish illumina cases is fine on the higher end um and then we also do some thrust calculations based on your nozzle dimensions to give you a simulated thrust uh this is currently in pounds and i'm going to turn these off so you know so in this case this is a pretty small motor peaking up around 40 psi or 40 pounds of thrust and i apologize for all my english units like i said it's uh that's just how i've been doing things forever but we do support uh metric units in here as well anyway so so what's actually going on here is burn sim is taking a look at your initial uh dimensions and everything of the motor calculating the surface area and starting with an initial you know pressure just atmospheric pressure and it goes back to using the burn rate formula here and it will calculate basically it'll start with okay the pressure is well 14 psi you know atmospheric pressure whatever to calculate an initial hop and it's got a little setting in here where you can choose your simulation sample intervals this is in seconds it's going to calculate how much propellant was consumed every 0.1 of a second and it'll iterate through that go through that over and over and over again and as it's doing that calculate how the dimensions of the grain are changing how that changes the the surface area and that sort of thing it's pretty straightforward people actually done this in the past with spreadsheets or done some approximations of it and that kind of a thing when you're using burn sim a lot i get a lot of questions a lot of time about number one oh what are you know what are these basic propellants in here and i give out the formulas for them like i said they're nothing special there's something on the order of you know a medium to low solids uh pretty typical family propellant propellant um where things get more difficult is if you're doing your own propellants and you want to characterize them yourself so there's that you know you get a little more you know your difficulty level goes up a little bit there and you have to have access to some equipment there's two pretty standard ways of getting the data you need to characterize propellant or to take a step back what you need to characterize a propellant are burn rate and pressure data points you want to know what the burn rate of a propellant is at a given pressure if you have two of those data points you can you can do a basic characterization three or more are obviously better but you need a minimum of two and uh in the industry the typical way of doing that is with what's called the strand burner which is a specialized piece of equipment which will burn a length of propellant in a chamber it'll have measurement wires in that propellant so it can measure the amount of time it takes to go from one from one one point to another to basically measure the burn rate and the chamber will have mechanisms to maintain a specific pressure so you know you can run multiple you can run multiple strand tests at different pressures and get a whole bunch of data points um for those of you going into the field and in you know having access some of this equipment in college you will probably get some hands-on with that potentially and that that's that's cool for for someone like myself who's a hobbyist that kind of equipment is a little bit out of our reach but there's a second method where they call it's often called a ballistic test motor which is basically a large heavy walled motor that's an end burner and will burn essentially a piece of propellant like the shape of a hockey puck a really big end burner and so the purpose there and you'll have a pressure transducer in there to measure pressure so uh in a perfect world you have like a hockey puck that's one inch thick all the you know one surface that burns the rest of it inhibited you have a pressure transducer in there you can light that motor you can measure the pressure in there and you can control what you're going to end up with as nozzles so you do one test one pressure test with a large nozzle and you'll get one data point and do it again with a little bit smaller nulls and get another data point and you get your stuff to characterize your propellant and then with that data um you can do a couple different things there is i'm going to take it to an ancient website here amarok.com is done by james lanier i this site's been around for 20 some odd years but nice thing about it is a very straightforward procedure for doing uh propellant characterization here's kind of a representation of that test motor that i was talking about this one's actually a little bit more uh well enhanced because it's got two different diameters of propellant so you could do this with a single burn if you the the hard part here is getting this entire surface lit evenly but ideally you could do one single burn you have when this portion burns you've got a one pressure and you can based on how tall that is you know how long it take you know get your burn rate same thing you'll see a transition to a lower pressure and so you get two data points out of a single burn but once you have that there's some math that you can go through and use to calculate your isp well your characteristic isp as well as your a and your n and get that stuff so uh there's also i saw a spreadsheet that i put out that makes it another if you run excel if you have access to excel microsoft excel you can use this spreadsheet this is another old website of mine rob burnson this is my personal website that i i can send these links out if anybody's interested um i have a spreadsheet let me open it really quick here and what this spreadsheet lets you do is all you have to do is you get those data points you get oh i have you know my burn rate at this pressure and you just have to plug the numbers in and it will give you the a and the n numbers that you're interested in you take those you plug those in the burn sim uh you have to wait for that to open there we go so as an example this is a real straightforward thing to use makes life pretty easy if you get those data points you have your put putting your test data you have your what pressure you got at what burn rate and the k n which is again it's just the ratio of the nozzle throat area to the propellant surface area here you see you got three data points it grabs them for you and it gives you these numbers there's this is a representation of the burn rate formula so in this case your a value is the .0174 the n your exponent is 0.4285 take those numbers plug them into the burn sim and you're off and running um the way that you plug those into burn gym really quickly you've got there's your burn rate coefficient right there your burning exponent right there uh propellant density is also an important characterization number but that's pretty easily measured now yet another piece of software out there called there's actually a lot of different versions of it uh pro pap that is a piece of software where you plug in the ingredients of your propellant and it will give you numbers like your density and the the st the c star value which is just another way of representing the characteristics characteristic characteristic isp which um that's a measure of the amount of energy available in a propellant and how much you can ideal world push out um a couple other things in here in burn sim uh there's something that's called pressured varied properties and this is something more specific to sugar propellants they have a tendency to the for these numbers your characterization numbers can actually vary at different pressures which can make things more complicated and a uh ammonium perchlorate propellants are generally pretty pretty flat you can ignore the changes there but with sugar propellants that can change more so if somebody wants to simulate a sugar motor in here and they want to have their characterization numbers that vary based on chamber pressure you have the ability of plugging in you can add you know a new value that says here's all my characterization numbers oops that was the wrong button i need to edit there we go you can put in characterization numbers you can say you know between this pressure this low pressure and this high pressure these are my a n isp values there's a few other things you see in here like specific heat ratio and molar mass those are not currently used in the simulation they're something that again are part of the trans startup transient and some other things where i was playing around with some thermal thermal dynamic calculations some other things where these numbers come into play but they're not used in the standard simulation so burnsim does a pretty good job of simulating a motor burn and where things start getting out of hand is in very high length to the diameter ratio motor so if you have a very long motor uh what comes into play there is uh erosive burning which is you know we're like you saw the burn rate formula where we're calculating our burn rate based on the propellant characterization another a factor that comes in is the speed of the speed of the gas moving through the motor down the core of the motor and what will actually happen is as that speed increases it actually compresses the flame front well there's a lot of different a lot a lot of theories and a lot of explanations of what erosive burning is but the short version is is the enhanced enhancement of the burn rate of a propellant caused by rapid gas movement through the motor and one of the mechanisms to theorize there is how as the gas is moving through the motor quicker it compresses that flame front which causes the uh propagation of the burn to increase which increases your burn your burn rate the problem with that is increased burn rate means increased pressure and what you can end up happening is um a runaway where you'll you'll end up with a case rupture um experiences personally ran into that when i started doing longer motors and everything simulates looks like it should run just fine but uh you have a motor on a test stand or a rocket on the pad you hit the button and it immediately goes boom and unfortunately the worst time for erosive burning is in the middle or i'm sorry is in the very beginning of the burn because that's when your core like in a base grain your core is the smallest and you intentionally have the fastest gas velocities moving through the motor one way to measure that is what we call mass flux which is basically a measurement of oh i apologize i figured off the top of my head but it's basically how much gas is moving through how much space and it's the higher that number is basically is kind of translates to gas velocity and or it's a representation of gas velocity so the higher that number is the more erosive burning potential you have going on there and again that's another propellant dependent variable some propellants will have a increased propensity for erosive burning others will be more tolerant in other words some propellants will a little bit of a of you know your mass flux gets up to a level and it'll impact the the burn rate a lot and other propellants it won't and a lot of the reasons behind that can have to do with particle grain size and propellant ingredients burn rates enhancers and that kind of stuff fortunately in the short term it's something you can similar to kn you can watch for where you start seeing burn rate changes based on mass flux so if you you can do some experimental test runs with motors you don't do a series of motors where you're where your mass flux is increasing based on the design of the motor and watch for where the burn rate starts going out of line with your simulation if you see that you know at which point using mass flux as a threshold that your burn rate's going to get out of hand and you can just stay under that and and one way you can keep the mass flux down or reduce your gas velocity is things like you'll see motors with stepped cores where the bottom grain will have a much we'll have a larger core and it gets smaller towards the top rather than having the same diameter all the way down eventually my goal is to be able to characterize and simulate that as well that will involve i mean the problems there number one is character is that characterizing erosivity in a motor in a in a propellant so one way that that can be measured is to do partial burns of a motor where the a a motor will be tested and then interrupted in the middle of the burn uh techniques for doing that involve explosively opening a case to try and extinguish the burn part way through which is difficult um and the the reasoning behind that is they'll go and look at uh expected burn you know how much how much of the profile is consumed versus how much is actually consumed and use that to figure out how much erosivity is going on a little easier way to approach that or at least the way that i look at it is to do again or your mass flux is increasing as you as you go collect data on those and then compare the results to what is simulated burn sim does actually let you do some of that as well you can take a simulated motor and import test data and then line that up against your actual uh your actual collected thrust date or not thrust data but pressure data um so you're doing okay on time i can try and think of where i have an example of that i jump to another computer here really quick where i have all of my personal simulations and things like that let me get this stuff out of the way and i'm just going to bring the burn sim here enjoy my wallpaper or rocket recovery uh i know i'm going to do that right now that's fine let me see if i have one of these motors i believe i have test data loaded for these are some 114 millimeter motors that i have done in the past there we go all right so here we've got a two grain 114 millimeter diameter motor that i actually flew this years ago but i had done some tests and runs and actually collected data so you can see here i've got a data set that i've imported if you're curious on how to do this it's pretty straightforward there's a tutorial for it on the website but basically you just if you have your data in a csv or in a spreadsheet you can actually highlight that data in excel copy it to your clipboard and then import it in here and you can also import csvs but i'll go over here to my graph lines and i can see here let's turn everything turn some stuff off here to make it a little clear apologize from a small screen on this laptop okay so we've got here's our simulated pressure here is our imported pressure which is oh i got to go over here and tell it to show me the graph the data there we go so this is fun where you can actually see okay the green line is my simulation i'll turn that on and off to make it this and the orange line is the actual collected test data from from from a burn this is actually a pretty good example this is a very well characterized propellant the simulation and the and the test data line up really good um this is not always the case and this uh if you don't have a well character that characters as eyes wow excuse me characterized propellant your number you know you're not going to get a nice something that lines up this nice um and also this like i said this is a two grain motor length diameter is very short for small so there's not any erosive burning going on here and so it lines up really nicely an example of where you start seeing erosive burning it would it will typically look like a pressure spike in the first part of the burn that doesn't you know that so you can like i said you can you can propellatize or i'm sorry characterize propellant figure out where your mass flux threshold is where things start deviating from simulation and stay under that uh you can design motors to try and keep your mass flux low you can also do a do a motor which uh is a very progressive burn where the simulation has a starting out at a very low pressure and what you are expecting to see is a erosive burning spike in the beginning of that but you take that into account to keep your pressure within within design limits early on and um so i mean that's there's several techniques to either deal with that you know like i said ideally i'd like to be able to simulate it but i haven't gotten to the point yet where i can reliably characterize that characterize a propellant for its erosivity and then define that in a way that you could plug in here and say okay you know it's given an erosivity factor of x that starts at mass flux y and have it start simulating additional burn rate based on that it's i've been thinking of ways to do it kicking it around haven't done it myself and i there's a lot of a lot of papers out there and a lot of research on on erasivity and how to how to predict it how to calculate that kind of thing so a lot of interesting reading on that as well um trying to think of what else might be interesting to talk about uh let me get back to hey greg popping around this is steve hey we've got a question over on the q a tab it's uh when using a ballistic test motor is it necessary that we use the end burning configuration or can we use other grain geometries well the idea you don't want the pressure well i guess you don't want the surface area to change during the burn so if you you could use a bait screen that's optimized to keep your surface area as flat as possible during the burn so so so i guess yeah the answer there is no you don't have to use a an end burner yeah he follows up with uh and this is a question from david vestal if we can use other geometries i assume we would use average pressure to determine the burn rate so that breaks me to wonder what an appropriate cutoff would work to give a accurate result that yeah so the devil's in the details on this stuff absolutely and uh like i said like i mentioned like when you're using an end burner configuration you're using a big they get big and it gets hard to light that surface evenly to get a clean burn that kind of thing um and also when you get that data you'll see you're not going to get you know in a perfect world you get a nice up flat down if you get that you've got great data but that typically doesn't happen you'll usually see your you know you've got your igniter and typically a lot of the time we've tried things like uh therma uh copper thermite and other things to try and get that burn to go and you're gonna end up with you know a pressure spike in ignition and then it levels out and then if it drops off that is a good indicator that you got that whole surface lit all at once if it kind of tails off then that's usually an indication that you know you had more of a you know not a flat burn but more of kind of a concave burn so those are challenges that you end up having to try and find solutions for as you go and it's um you know other things too you can put like likes used in a strand burner you can put uh burn wires in you know thin wires at different points in the propellant and measure that along with your data and that can be used instead of just oh the propellant was one inch long and took this long to burn you can actually have different data points in there to measure oh it went from from the i know the wire was at this point and at this point and you know take your measurement there so there's options another approach that is a feature in burn stem that i'm playing with it's enabled i don't it's it's very experimental is you can take a motor and design it and burn sim and then collect your test data import it into burn sim and then there's a feature in there let me jump right back to really quick where you can characterize characterized propellant yeah the magic button and what that'll do what what it attempts to do is it actually runs a whole bunch of simulations it it very it takes characterization numbers and if it's doing a whole bunch of simulations here and you can see in the background the graph is kind of changing what it's trying to do is try different iterations and get and then every every iteration it measures how far the curve is from the actual data and then it will continue to do that until it gets the closest that it can and say okay this is what i think your propellant number should be and so this is something that you can use as a yeah you know a swag at you know if you're in a hurry you want to get something ballpark and you have some test data you can you can use this feature to to get in the ballpark and it's you know like i said it's experimental it's kind of fun and you can do it with any motor obviously the more simple the motor the better um and you do not do it with a long motor if there's a receive if there's erosive burning going on in here then any results you get from this kind of an approach are going to be completely wrong and like i said it's experimental it's buggy it's throwing exceptions here it is enabled though so it's there if people want to play with it um but yeah there's there's been a lot of different approaches to doing ballistic test motors to pre characterize propellant because that's your first if you really want to get some accurate simulations that's your first step you got to do you got to have you know garbage and garbage out you got bad numbers on your on your propellant your simulations are going to be meaningless all right we got another question here uh it's about smoke grains and when testing motors we static test with should we static test with with a smoke grain and will it impact the pressure rating oh it absolutely will in fact you're reading it's propelling it contributes to the motor what i personally do is when i make my smoke grain i try to well you can do different things but i like to have the smoke green actually consist of two layers there'll be one layer that's the same propellant that i'm using and i'll target that thickness of that to match the web thickness of the motor and that can actually be added to burn sim as an additional and burning grain so you can simulate for that you can also burnsome will support simulating a motor with different propellants as well so you could characterize your smoke grain propellant as a propellant and and it'll it'll handle that as well but it absolutely will affect your your uh pressures and in fact i had a case where a guy a friend of mine had him had a 38 millimeter motor ran great decided to throw a smoke grain in it and it catered because it added enough pressure to to over pressure the case so yeah you definitely have to take that into account very interesting actually yeah the heat of those as well is something to keep in mind as well if you have a smoke green a long smoke grain that keeps burning you know 5 10 15 seconds after the motor goes out that generates a whole heck of a lot of heat and will really heat your case up as well so yeah another one of those things to keep in mind uh let's see any more questions uh you know one i have a question about strand burners i mean um i i i don't know that i've seen a commercially available strand i don't think there is one it's you know it's it's things i've read about papers i've never even seen one in operation but you know the concept is a a pressure vessel that can maintain a given pressure and and then you you know you can burn your your strand in there and measure the actual burn rate excuse my cat it was perfect we're open for question guys anybody have any other questions you can put it in the q a tab was there anything else that you were hoping to uh to show or anything else you would like to show everybody um nothing that's coming to mind i mean like i said this is a fun thing i i i enjoy this as a hobby i've been doing it for i you know i got hooked on rockets when i was a eight-year-old cub scout and over the years you know high power became a thing got into that making your own motors research experimental whatever you want to call it became more popular was able to you know get into that and that's that's you know if it's not it's not a way to save money you don't you know unless you're unless you're flying you know nop motors on a constant basis you're not saving money there's a lot of investment in equipment and that kind of a thing but it's a heck of a lot of fun bernie motors on test stands lots of fun um always keep the safety aspect in mind especially if you're doing this stuff you know on you know there's the schools are good about you know keeping that and but when you're doing the stuff on your own i've had i've had motors come off of tents test stands i've had motors fly test stands you don't always realize how much thrust is there and you think oh my you know i got this big steel test stand it'll be fine and next you know it's flying across the field um so you know if you're doing that kind of stuff safety first always you know the alive uninjured and out of litigation is always assume it's going to fail in the worst possible way and if it does that what's going to happen you know if you're if you're testing a motor in your backyard and it fails in the worst possible way it's going to break off the stand fly through your window and burn your house down and you know if that's the worst possible scenario it's not the right place to test a motor if you test that motor out in the middle of a desert and worst thing you can do you know it breaks flies off the test and explodes sets everything on fire and you end up with you know a black spot on the ground but you know okay maybe that's a little bit safer way to do a motor test sure yeah hey there are a couple of questions that have come in uh if you had a model erosive burning how would you go about it so what i'm trying to do well you know the way that i'm approaching that problem is you know because that varies based on a propellant you know different propellants or behave different ways need to have a way to number one measure that or you know so i you know my approach is doing test motors that have short motors moving into long motors so your your mass flux is changing and identify you know look at your test data and identify okay mass flex gets to here i'm seeing the burn rate accelerate this much mass you know mass flux is higher the burn rate's accelerating more and quantify that in some way which obviously i haven't nailed that down otherwise i'd be doing it in burn burnsome but quantify that in a way that you can't it's probably gonna what i'm thinking is gonna end up being a burn rate enhancement factor that is based on your mass flux so as the mass flux gets higher it's going to increase your burn rate by this much um and then being able to simulate that also becomes more difficult because you have to take into account okay my burn increased and now my propellant regression is actually this much more and that throws off that also changes at different points in the motor because at the very top of the motor your mass flux is very low and so there's going to be almost there's going to be no erosivity but at the very bottom green of the motor the erosivity is very high and you're going to have more so right now burnsden assumes the same regression throughout the entire motor with taking erectivity into account that doesn't work anymore now i have to keep track of okay the bottom well if i do it by grains okay the bottom grain is expanded this much the core the bottom grain the core the next grain is expand a little bit less but in reality that's still only a best guess because it's not doing you know because the mass box is increasing going down the motor not just grain by grain but you know millimeter by millimeter so it's realistically going to be turned into a three-dimensional simulation of your motor because now that base grain instead of just burning like this it's now burning like this and so things get really complicated really fast yeah well he does follow it up with is there any other software that does it or is there some way we could he i don't know if he's offering but i don't think so but is there a way to add a plug-in to burn sims uh currently there's not um open rocket is an open source motor simulator which not i mean obviously i'm not in this for commercial i do charge for the software but i'm not making a living off it it's not like a commercial game so open rocket technically i guess would be a competitor but that you can get involved with and i know they've been talking about erosive burning as well so if you're interested in getting more into the software side of it i would recommend looking at them and potentially participating there and i'm pretty being an open source project you would be able to do whatever you want with it yeah i i know that some of the other schools are looking at uh augmenting uh open rocket with not not more of the [Music] uh laminar flow type stuff but um uh but at any rate yeah so yeah that was that's what i thought the answer would be to your to the yeah there i know there's other software there's that is like not commercially not commercially available where it's used in the industry and in the schools and it's i know the software out there but um that's about as far as much as i know well this is sort of the perfect next question is is do you offer licenses to uh spaceport america cup teams looking to try srack um yeah actually um probably gonna be just doing free student licenses here going forward pretty soon just i mean we've i've had some schools approach me and want to buy like large chunks of licenses for classes and stuff and we do discounted licenses for that but i'm getting to the point where there's i mean for education and students i should just be giving it away so that's watch yeah i know that we've had a little that sort of discussion in the past and so you know i know you've been very generous with the uh college students so thank you um then there's one last question we have right now which is uh for the strand burner when you say it maintains a constant pressure does that mean it has to release the pressure when the propellant burns yes yeah it has to i've heard of ones that you know you can't will bring the pressure up to the value that you want and then you start the burden and then yet it will vent the pressure at an appropriate rate to keep it at where you want it so if you want to do a test at 500 psi it will event pressure to maintain it at 500 psi or a thousand psi or 1500 psi and obviously that's a pretty complicated thing to have you know you're gonna have to have some pretty good sensors and valves and and those kind of things to do that and you're not just dealing with room temperature gas you're dealing with you know combustion products and stuff like that so it's it's uh compared to a ballistic test motor it's a pretty complicated piece of equipment uh any other questions out there don't uh don't see anybody with any other questions um i just uh really want to thank you greg for taking the time to present to the to the to the teams and uh really like what you're doing i'm uh i have about uh a foot and a half into the srad motor development at this point i've done a few use your software for the last uh two years so your contribution to the to the hobby has been great and uh thank you for it thank you my pleasure i'm glad i'm i'm excited to see it being used well that's great so with that i think we'll stop the broadcast and again thanks again greg okay good to talk to you bye