My name is running some I'm Rajan Mantri I mean I'm in the UK And as I was that I mean it was the sling loads are used for very many different types of helicopter missions. They're used for board carrying things like water foam and fire retardant for fighting force fires to aircraft vehicles and artillery for the military but when a helicopter carries a sling load it may encounter some stability issues that will affect the performance capabilities and could potentially be a day or two examples of a couple of hearings our project. Developed from a three year proposal to the vertical lived right across center of excellence to attain stability and performance standards for the U.S. Army by observing the dynamic characteristics encounter when carrying the sling load and in our project we've done lots of wind tunnel testing and it's been done in the seven foot by nine foot test section of the John Jay Harper Wenzel facility and we've been doing testing from air speeds around five to fifty meters per second. The testing that we've been doing is on a small scale model of a comic's container which is just a rectangular box basically and it will be described for later on there are many are aerodynamic concepts that are relevant to the sling load research project we've been working on first of all the sling load it's been set up in our winter. No by having amounts system of the top and then a set of four wires extending down from it to the edges of the of that sling load container and as the airspeed increases as a freestream speed increases in the wind tunnel the sling low starts to swing backwards and that increases the trailing will between the axis of the Mount and the axis of the main center of the box of the conics container. So basically in those interactions. There is different. Movement both in the in the pitching motion there can be roll and ya with the bustling load spinning. What can also happen is that we noticed in some of our testing is that it can start going clockwise and then counterclockwise and spinning back and forth and the main thing that we want to try to identify are some of the unstable cases because these are these are the things that affect the helicopter performance and the safety issues as mentioned earlier. The stable case is found when there's a there's a steady rotation going on with the with the sling load conics. As this as this freestream speed increases. It's also important to note that there is a dynamic coupling between the helicopter system and the sling load in real life performance. So that's why it's very important for the helicopters usually to say very steady when carrying a sling load because both the forces on the sling load and the forces on the helicopter both closely linked. Some of or text affects are also important because the rectangular conics is in a very aerodynamic shape. There is some fluid separation from the edges of the conics and there can be for disease form from the edges that lead to a turbulent flow in the wake region behind the conics container and this once again can cause more unstable effects such as vibration and torsional motion. That will end up affecting the stability of the system. So one of the things that the previous research that we also looked at which was with the Technion case with the Israeli Institute of Technology we looked at their data. Tried to use that as a basis for our our research and what they did is they applied fins at the rear end of the of the conics container and that allowed them to maintain stability at higher speeds. That's one of the things that we're looking to develop later on and that will be talked about later in this presentation. Another factor is the reduced frequency which measures the oscillating flow in the system and the flow around the conics container as it goes around and this is this question can I give a representation of it would be the angular frequency L. is the length of the container over over the free parallel to the free stream distance of the flow and then v is the velocity of the free stream. Drag is also a very important factor to consider for the sling load system as mentioned before as a speed increases the sling that starts to push away and increase the trailing on the trailing Will has a relationship with the aerodynamic forces with the tangent of that trail angle equaling the total drag over the weight of the sling load system you can then up to CD value the drag coefficient from that by using C.T. equals the drag over princes one half times the density times of the flow velocity squared times across sectional area and what we did for that cross sectional area is we took the average based on the rotating conic section. So it's not a square it's not a cube box so there is a length within a height so we did the length and the height and the within the height to get the narrow and and the wide end of the conics as it was spinning around and these are some different values for for a textbook data for for the two D. case it's two point zero five for three D. case it would be one point zero five and from that Technion data that we analyzed before using the measurements. It came to about one point zero two for the CD. All right. Testily. And said We are still a little bit bigger than entering and it hinges eight point three as opposed to their nine point three by three point seven by seven. I'm not a little bit heavier around one point eight gentlemen over there one point six four and our sling link was a little bit shorter which is just all that is is the wires that attach box. To the mouth is done that we had our scaling factor which is in with eleven and all that basically means is that for the height width and depth of our times eleven would correlate with the comic section for math it would be in Q one of three or in the last year for our National Design we had a cardboard box with the dimensions and so forth. It was reinforced with tape on the edges and corners. We're really starting to work with our revised design which is the by wood and it's headed by wood and it has a removable we might want to change the way or other factors in it and this love more flexibility in our you can ration attaches with integral brackets to avoid any error dynamical So these are pictures of our initial test with the cardboard box and you can see right here this is the close up of it that cylinder brought it all together for one point we also did a test which isn't pictured here without the cylinder and we're going with four different points and here's some data from there are four point without the cylinder. It allows for more torque transfer to the management the amount actually fun which is what we were hoping for to use those really good. It was more steady it formed a little bit you know all the ladies but nothing too bad but the single point now which is like. You just saw a picture there was far more variation trailing a lot higher. There were the torch transferred in the mouth. So we got the wires which caused a problem because we were there to see it when you try to measure that in the wires are going one way and so that kind of that is that of the single load when it happened. It's strange because it was just twisting and untwisting and we didn't know the big restring there were it was just residual effects and so we took a string and strained it and then we turned the wind tunnel back up to about thirty five miles an hour and then we released it so that we could get work that I used for the trail angle was thrilled with the flow of this kind of weather and the intro the fire truck and would go pretty much like this for the snow around them trying to get more and here we have the graphs. This is for the triangle that if you see the blue dots are for the single point of the plate is for constraining the low strength of the thirty five and the other green is the four point right. Is that there. We have from the taking on they have been in the what is the predicted here we have the trailer the Greens versus the still being just go from zero to five more than a scaled up knots and as you can see the blue line is a predicted line based on the breadth of vision. You know and then we use that for the mentioned already was very sure a little bit higher than what we predicted which you know we're trying to work right is trying to see where the earth goes from here is from the rotational raids. Again it's R.P.M. vs the scales be an interesting thing we found is that after a certain speed people come to love the love that around thirty R.P.M. and the other. From are using the earth this frequency of point zero four. We saw that the rate of the rate of change in the air. Lots of variations seen the following in the case from a certain range so that would go with you as an eel and Rachel just talk to you. Problems getting Tess one of the main issues that we encountered was that you're using materials we use slang for the connecting with love to them and we recently just used for nylon string that created all sorts of issues with the White House so we're going to be working on different materials you can also arm out the amount that we did initially was in the ball bearing but the ball bearing was designed using one orientation in order to set them out and one time we had to put in opposite or errors and accomplish all we were. Using videos and we're getting direct and house direct measurements downloads and the video cameras we only have one view this is redemptions we're going to be updating our mouth originally and only have two degrees of freedom. We're going to be a thing as a as three he's also going to be introducing a new album coded system which will give us more direct measurements which will increase our act of our houses and then you might we're designing is more is closer to what is actually hardly being used by the U.S. Army in sling loads our future plans as I said we're going to be. And we're going to be using more video cameras to give us better views. We're also going to be testing different shapes because most helicopters don't just carry just boxes as Dr Lee said they're also vehicles artillery other weaponry and in firefighting it's that it's more so. So in general objects. He's going to have different weights are going to get different lengths which we also have to take into consideration and the different materials I'm not sure it's a good match the conclusions. The research that we're doing is helping us understand just what Perry dynamics are occurring in the sling want to help look out. We're seeing that the stable spinning modes are driven by the aerodynamics forces and should have nothing to do with the cable interactions and our results can only show that we are getting higher direct of vision for container than I was reported by the Israelis and that you know now would take any questions like How do you know you know you know the size zero because her lights out. That back could be a factor that could be accounting for the you know we didn't we didn't scale it separately we just had that the dragon that I mean the area is based on the length of the with which is one to run from a from a scaling and it was a revenue but it's in an linear scaling for that we didn't do any separate things on that CD value so that could be a case for the errors but good to know that as well we use that same calculation for the Technion analysis as for our own wants. So they got using their data we got about one point zero two and then using our data it was about one point one point six one point six five for City. It's all use it wasn't a competition but it came from a proposal and so this is really the initial stage of it. We just started work on it in the middle of January of this this year so it's just a stunning misstep for the conics and sling lot of research work leading his right. You believe they will work they should go right right. When the when the sling load is it is located on the on the on the from the trailing that has the speed increases the trailing also increases and then that can cause the form of the different ages and it's not necessarily it's not a completely symmetrical shape. Which can also factor into it but there is a variety of different her dynamic forces that cause some of that rotation we haven't really gone in depth into the area dynamic concepts yet where crime more focused on the initial testing and seeing the results from that. That did it. If there's anyone else that wants to go for the explanation. I said I mean you know it's also based on those forces as I mentioned when we had it with a single point system we did observe that it would it would regrow today in one direction and then it will rotate on in the other so and again that could also be the factor was there. Why are you getting tangled which which affected are the accuracy of your data on that on the single point. Systems but the stable case is found from our previous research on a literature survey on previous research done on sling loads in other companies and in the industry that the stable case is when there is a rotation because otherwise the slow can shift back and forth they can wobble it can all oscillate and vibrate in different directions which affect the stability and performance of the helicopter itself because they're closely were linked in terms of their performance and stability. As when I wrote a comic book well I think it's pretty doesn't prove this is as was known as the rights to the states when it would start just like mediately red tape. First it would kind of want to know and then the rocks. Just get more mileage. So finally you start the bones. You know come arrives and that's what it seems. Once it's done with any other questions. Well the challenge in time right now because since this is one of the first that's when you know things like you know this is all you know it's a it is a good wives but it's no I'm getting all of the so you know your lawyers trying to Tori together. So I guess eliminators them and to follow up on the other challenges are like we mentioned towards the end is looking at different configurations because they can separate thinking significantly impact the performance of how the sling load acts so affecting the amount of weight. We place into the sling load affecting the sides itself because just just to let you know that the Technion case there was performing a much smaller one meter by one meter a wind tunnel so eventually we're going to scale up our own Conex container to a much bigger size since ours is seven feet by nine feet rather than three feet by three feet. So looking at different size is different weights different materials. There's a lot of different data that can be Manipur different configurations that can be used that can affect the data results. I think the main purpose of this study that you know what we're really you know the helicopters all over the place that helicopter and that can be really unstable is that what we're trying to do what exactly is causing all this trying to fix it so that you know you know we can make it safer and better than hell.