U.S. official reveals the reason behind Zelensky's Washington trip. A top U.S. official has explained the reason behind the Ukrainian president Volodymyr Zelensky's surprise visit to Washington on Wednesday. In an interview with CNN today, John Kirby, the Strategic Communications Coordinator at the National Security Council, said that Joe Biden invited Zelensky because he believes the war in Ukraine has entered a new stage. The president really believes that as we approach winter, as we enter a new phase in this war, Mr. Putin's aggression, that is a good time for the two leaders to sit down face-to-face and talk, Kirby said. The official noted that the two leaders might also discuss how the war will end. I have no doubt they are going to talk about President Zelensky's notion of a just peace, Kirby went on saying. Mr. Putin is obviously not interested in diplomacy right now. Quite the contrary, he is interested in killing more Ukrainian civilians, Kirby said. The official noted that Washington's ensuring Zelensky's safety during the visit. Zelensky traveled to Washington today in his first visit to U.S. since the start of the war in his country in February. Before the trip, Zelensky wrote on his Twitter account that the visit was aimed at bolstering his country's defense capabilities and also included discussions around the U.S.-Ukraine cooperation. The visit comes amid Washington's announcement to send Ukraine a $1.85 billion aid package that will include much-expected Patriot missile system.


The Deputy Speaker of the House of Representatives rides Honourable Benjamin Kalu as the short members of the Transplant Association of Nigeria of the House's Rediners to collaborate with the association to set up facilities for treatment of cases of argon diseases in the country while receiving members of the association who paid him a katsy visit in his office in Abuja. He lamented the high cases of argon failure and a $1.2 billion spent to treat the disease through treatment abroad while present members of the association for assisting their lower flying their trade and choosing to serve their motherland. The challenge of argon failure is not only a medical concern but also a societal one. It is encouraging to note that the Nephrology Association of Nigeria has reported over 700 kidney transplant carried out within our nation so far and that deserves a handclap. Can I tell you that one or two persons I know in this room pass through the knives of these experts and you will not know because of how well the job was carried out. Earlier the leader of the delegation Dr Olalik Olatishe had called for financial assistance from the House for the forthcoming conference of the association in Abuja which is meant to serve as a venue to sensitize Nigerians on the activities of the association. The scarcity of organ donors all over the world and so what they are doing in other parts of the world now is to have a disease donor program and you are aware that for us to do that in our country there must be some legislative backing must have the right laws in place to be able to carry that out and as you are aware we have a problem here where quite a number of Nigerians think that the power of reincarnation when they come back to this world they donate an organ even when they are dead they may convert and they may not be complete and so we need to change this narrative so that people who are living can have an organ transplant done within the country and as you are aware the prevalence of chronic kidney disease on the right so there's a need to have such an organ band


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So tell me what kind of people do you work with every day? Well in clinical research you can work with all kinds of people and departments and specialties. Those include your PI, your sub-investigators, which are generally physicians. You work with nurses and nurse practitioners, your fellow coordinators. You work with budget and financial analysts. You work with big sponsors. And really many vendors that are involved in the whole clinical trial process.


that is like super bright what's up y'all hope there goes Bowie he goes wherever she goes what's up y'all what's up y'all hey guys what I've been working on today it's taken literally all day maybe if you guys asked just nicely he'll give you a close-up tour. Maria all the way from your Rico Springs Arkansas is it it's our Kansas or Arkansas it's the same difference right so I try to make it darker but then I tap on you and then it just goes vampire white. So let me give you guys a story behind this piece my best friend she was my college roommate we worked together for forever she lives in South Alabama we call it LA and she saw a piece in a gallery and she asked me if I could make a smaller one because it was 5 grand and she couldn't spend that much money don't blame her so she sent me a picture of it was like can you do something similar in your style and I was like sure this is what it looks like yeah and so that's what I'm trying to do so we can deliver it on our way down to Florida we leave on Tuesday so if you guys have nice like you may take you guys for an up close this is where I'm at up close view is that picking up everything I shouldn't all these little sparkles hopefully will stay on I think I was gonna say I think when you put the resin on it's going to well the main reason why I wanted to go ahead and add them under the resin even though they probably will get lost is so that they get stained with the inks and also we'll leave these little dots if they move it's okay he's so like scared to run by me like dude I think it looks like an underwater like right so that's what that is now because I'm limited on space hey guys low e beans this is done with alcoholics thank you so because I have limited space I'm gonna have to resin these sums of guns one at a time if this were a triptych where the design was in resin I would keep them together but since I already did the design where the resin doesn't need to stay connected they're not on canvas they're on custom cradle boards they won't be expensive but you're gonna have to take one check it be it may be set by now the wave you can go ahead and de mold it and just you could still push it so I'll probably leave this set up for a couple days actually I'll probably leave it set till we get back from Florida that way it has a week in the same shade oh you can see that I wonder the crystal and you can see the you can't even see it though here it is oh because this is all right yeah it's not shiny this is the thing though like I think it's gonna be really rigid because it's I mean it's I can kind of push it but not as much as yeah normally it would droop but y'all this looks great I don't know if you can even see this beautiful is that it's gonna take for all three of these so I'm just gonna come out the gate I wish you wouldn't walk around here you say hi to the people okay I'm also working on my dad's memorial flower oh yeah that's got three coats of Mod Podge and two coats of spray varnish so far I'm gonna do a couple more tonight and then let them dry overnight and tomorrow I will go ahead and seal it she has a question for you I love it Glowfish this tripod I'm using right now is as the original one the one that I'm gonna recording in my area I love it I haven't really got to use it I'm just getting used to it being there and setting it up with with the laptop and whatnot but it like I've had my camera on it and it holds it like it doesn't move you can you know have it right over your work or above your work and it's it's a very it's three extending like like these right here I'll try to go slow I just got these little guys for our cameras they look like the what do you call it what are those called yeah like like a desk lamp and what and what I've done is these were microphone stands so they have the wrong size fitting so I just took some JB weld and got a one fourth screw screwed it into the bottom of this and then JB weld it to this arm so you can this is on there it's not going anywhere I can unscrew this but that attachment is on there for good but these work good for just like and these were $11 on Amazon the one that I have for my DSL camera is 111 which is so worth it because it holds mirrorless DLS ours so that mirrorless is a very light lot lot more light than your normal camera I believe that's the term they use well silver locks Paula hall Paula hall not Paula wall Paula hall where's that oh Paula hill thank you Paula so I am separating this a little bit and stirring it so that I can make sure it's completely incorporated ocean what's up my doing this maybe a little overkill but I'm a better safe than sorry type of artists when it comes to resin yeah it's and and glowfish it's so worth it it gets your camera up and out of the way and and I'm going to tell you it comes with two extra springs and what that does is it it basically tightens up that I guess it would be the main arm that that to where you can make it stay at a you know a pretty decent over your work level so it and it won't you know dip down or move or fall over um but it's definitely worth it what what happened no that's an old piece Linda that was one of our first stencil pieces carry it's it's worth it it's worth it just even if you just get one camera for now get a nice holder I mean it's a big difference and it's it's well worth it every birthday ocean and these uh these cameras these days are not not very expensive now I just got a full hd pro 90 degree so it's like a wide angle just for my area for 66 bucks 1080 hd camera yeah what what would happen if you didn't spray it but you sprayed that but not with this I'm I'm thinking yeah I'm just off camera spraying these other two canvases he's like right underneath you come here oh that could have been horrible to your usually do um it is crylon gallery series maybe archival 1387 matt looks like this so how many layers should I put on what do y'all think thanks glow I hope so I mean I told her I don't like recreate other people's work exactly but that um I would do it my way I do like the challenge when people ask me to do stuff that they've seen that they like um and then I get to try to figure out how they did it and what was used and certain techniques I like the challenge of reverse engineering inspired pieces if I knew the artist don't give them a shout out but I didn't see a single turn they have me so the spray is um an archival spray so on one hand it seals in the alcohol links and keeps them from fading and bleeding with the resin and secondarily they um I don't know if that's a word I feel like it is I think it is a word it also gives an extra UV layer protection from the sun so it won't like discolor and fade from sunlight I think secondarily is a word if not it should be I like the more you say it the less it's going to sound like a word so mixing resin like this and two buckets and switching them around to make sure everything's fully incorporated it's great to make sure everything's mixed well but it also mixes a lot of bubbles in so we're after baby said it and watch it with a heat gun make sure what does roughly one more and then we'll dry it and get on with it so look what I made today y'all how was that maker space and I learned how to make stickers I got black white gold and pink how are some is that I gotta get some new I gotta get some different um yeah I know the gold is awesome but uh this sticker transfer paper it's not good for this gold because the gold sticks to it so I have to get different the the normal paper like this white paper this is like shiny you can see it's kind of shiny um it sticks it sticks to it this is what you do is you take this off take this backing off and then you put this on whatever you want it to stick on but but this is this gold is stuck to this paper so you can't use the chrome or the gold chrome with that paper but with this paper like this is like you can see it's like a regular paper this doesn't stick to the gold so I've got to figure out some different paper to use but everything else is awesome and yeah I gotta make some so I know this is not the ideal dryer for this but it's what I have handings that's what we're gonna need oh no do you guys hear that pitifulness wait it's literally he can literally he I know he could he could jump over this I know you can't can just jump jump it's all right at this phase I'll just eat over the resin a little bit and darken it to some areas good boy it's shiny from your side it looks satiny it's a matte so the pink the pink looks good on the rose gold he's over there in his toy Bowie loves broccoli stalks like the and his fiance fan of course hey lost art keeps him from coming over here I know y'all Jeff just put tape measure down and it's it's basically stopping him from you know what is it Bowie get it he would be whining right now if there was a gate like if there was this right here from there to there he would be whining this fades at all I'm just gonna add some ink to the top be careful to use glitter glass sometimes run your hand across the surface you will cut yourself you ran by it how you moved it to the side kind of but I figured if it was moving you'd be like oh it moved scary beams and soft and not faded I don't want too much resin on here so I don't want it to take forever to dry because we have to put it in a car and travel with it I don't want it to bend because I don't want to risk pitting and having to do a top coat so very much catch 22 maybe you took it off and they've been back on um not too um I want to risk it pitting I don't know what this archival story does no one's talking they're talking amongst themselves Nina Mandy now my reference has chunks of looks like glass on their piece so I'm gonna have to do that as well Larry those birds are across the street like when we first moved into this building they used to be right in front of our building because there's a whole line of trees just about five feet in front of this building and they put some stuff on these trees and those birds don't go over here anymore thanks pf are you going to put any blue glass in there this glass does not have the mirror on the back because I don't even know what crane what crane fell where I don't I I know it when I drove from makerspace today here I stopped by Home Depot and over by Lovefield that area was trashed I mean it looked like a tornado went through there and it wasn't it was just the winds see what y'all are saying just for a minute so Jeff we're gonna put you on that yeah and you're you're probably hearing the birds that are way across the street like there there's none in this tree and these trees out in front and they're just kind of like flying around this reference has a lot of glass and a lot of texture I think I'm going to only put the large chunks down here and then use the fine glitter glass for the in-between areas do you remember what goes where yeah this is the far right side I'm picking out any of the larger chunks too I'm not sure why I think I just like it better this way and I'm flattening them so they're sticking like way vertical I'm adjusting it's like she stained some of hers I assume a girl did it but that is going something so I'm going to use some glitter glass which Judy has fronted me because I'm out most I hope it doesn't get lost I don't think it will laying on the top like it's catching the lights so well and just a a pro tip and I'm just saying this because if somebody asks you to do something like this and there's a lot of white negative space in there add a little bit more to the price because it is so difficult especially as an artist and if you're doing it to keep all this area clean without a spot without a wipe without a mist or overspray especially if something is in the center and you have it completely white on the outside surrounding it is oh my gosh it is such it's so difficult I've had somebody ask me why you know a white one was more expensive than one that had a background and that's the reason is because it's so difficult to keep it clean and nice and classy I mean you have to be really careful with with actually doing the painting itself because you will definitely ruin it with one fingerprint or overspray or dot or splatter or like one of the a gold background like using the the uh this gold here like this stuff is amazing it it it looks like it does on the on the top of the can but if you put one tiny fingerprint in that anything if you try to wipe it if you try to respray it you have to completely cover the entire piece again thank you Larry are you painting the ocean um she is not but it sure looks like it doesn't it she is doing a triptych or the two other pieces over there she's she's adding the glass to this one and then we'll put it in the dry zone and then grab the other one and do the exact same thing to to all three of them in the little bowie pants looks good babe all right I was debating on whether I wanted to add more um more of this the darker sharks but good happening no no no hold on babe you're gonna drip that spray sealant to try to keep everything from fading I'm using this UV archival from Krylon I still can't see what you're saying because I've got my reference up sorry y'all so if there's anybody in here from Florida uh around the Neptune beach or Jacksonville or Tampa uh or Lando we will be in Florida on Wednesday we are going to look for some class potentially class spaces uh to try to have a class down there sometime in September which we looked it up and it sounds like it's hurricane season down there then so it might be a little bit later who knows oh lovely well we just need a space that can hold at least 15 people comfortably and have uh electrical outlets that that can withstand a couple heat guns um and parking we'll set up a class so you guys can come to the sunny state what's sunny state sunshine state sunshine state will you touch it and see if it's sticky uh huh it's not that bad with this mat on it really it kind of blends it all together you said that was the only sticky spot uh yes linda it is it is a commission piece and uh each piece is 18 by 36 so a total of 54 by 36 it's like four and a half feet by three feet um what was I gonna say uh but if you if you space it a little bit I'm sure she'll probably space them a little bit like these have like a couple inches in between yeah so it'll probably be around 56 crazy g-lady welcome hey you can't run and bark boi you running like you are scared moose that's enough hey do you catch him before he barks no but he's moe cute all right by katter what's up nene what's up nene I wrote you back but I haven't checked email today confession oh we got some new colors in from color obsession you know she just did uh one of the pieces uh the other one is sitting and waiting over here on the couch of course boi is protecting it and it is green I was really concerned but I really like the vibrancy it adds you know what I'm super excited about with this piece is that I don't have to stress about things landing in it because it's a textured piece yeah that's always good that's that's one thing y'all pro tip getting all of them if you if you just have so much trouble and and and you're down to the to the wire and the deadline and you have one more day and there is trash all up in your stuff and it's just you know your dust free zone is out of commission or it's full and just add a little glass add a little glitter and that will get rid of any kind of dust that you'll see I just realized that I didn't add any heat to that piece um if you could take a torch do it in a minute yeah and hopefully it won't be too random of where you have it laid out on here I'm following the flow of the and I can always like hot glue some and post-production yeah gotta get a man torch why that makes me nervous only is it fire it's jeffrey with fire so that's even extra scarier two things I mean message today and was like what's my piece like what's the what's it called like that you're using is it like watercolor sit down this is like adding glitter without adding glitter blonde java she just left it white she started with white and gradually just faded in the middle right yeah record the process so I'll be posting that probably on Tuesday while we're driving I'm gonna have to do a top layer probably it's repelling off the sides probably what's happening just because he's on the chair no what are you what are you doing i'm getting fire oh i just did it last one you guys now he's getting mad who does like don't you do that to me yeah thanks for watching you guys I know we're not I know the mods are taking care of y'all though and with fire here you guys go over there molly stop it you please you guys go over there go I'm gonna have to do another one of these but with matte all right I don't need this anymore so I can pull up where you y'all are talking about oh uh thanks Gary move don't you jump I don't care how bad it gets um stay out um we've never buffed anything you just have to you just have to make sure you have a good dust-free zone um and a lot of the times you're the only person that's going to see any little dust or specks or oh we don't get a perfect one every time for fair if we if we have one that is too flawed like noticeable flaws then we'll use that layer as a base and sand it down so that the top layer is transparent so nothing's really wasted and thanks for saying that y'all so buffing is um a graffiti turn I guess where's that turn from I think she was just meant buffing the resin no they said buff it out as as in if it has too many flaws to buff it out I'm I'm taking it as it's buffing over something that's a graffiti you're thinking of I'm talking about like they went over it because it's that bad um we're talking about like complete cover which would be graffiti turn for buff with a glass and then inking over it again makes it look really underwatery it may be sticky because all the heat meeting glass I think I have this fire glass on my Amazon down in the description as well as the glitter glass glitter glass I mean it's so pretty let me put it in this first I mean it's literally just ultra fine shards of glass if you don't make sure resin well I highly encourage people not to scrape the sides of their bucket to get all the resin out it's a great way to get weak spots on your surface but if you mix it really well then that's fine what I'm hoping I just made the perfect amount of resin and it's not just under um what is that corkers corkster corkster if you look in the description box below the video there's a little arrow to the right if you hit that it'll drop down information of pretty much everything that we use um and that that amazon sells and if you go do what we don't care it that's where we get it yeah and if what oh nothing I don't like those random yeah like I took those other ones out because they're it's too distracting it's amazing the depth that resin gives again if you put any glitter glass in your piece before you resin it don't just run your hand over it because you will cut yourself I'll post the tutorial or the time lapse of how I did the painting part of this for Tuesday's video did you sponge it Heather wants to know did you sponge it I used a felt dauber for a part of it one of these things you don't have to buy the Tim Holtz thing you should like save money and literally just buy a sheet of felt get a wooden block a little bit of velcro staple the velcro to the block and get your felt on because I was kind of amazed at how much he charged for something so simple so simple you do you want to do the glitter glass fun shard I'll leave it actually it's probably gonna look out of place there are two pairs of gloves if you guys do this with glass to be sure you can go into the white with that and the drop a glob this is great but often like some more reason this is so fun right then we're basically done with this piece y'all yeah I'm just gonna say just do like one up there I don't even know who I am that I forget to add heat to this we'll come back around and hit it with heat again where are you gonna put that I'll leave it here shut these windows where else we can put it he's jumping he doesn't know the procedure yet stop nibbling at your brother mm-hmm thank you all right you guys whoop thanks for watching and seeing what we're up to I gotta take the boys out because they're getting super antsy antsy spancy they're gonna just shed all the hair on the piece that's fine because it's textured and whatever um check us out on facebook snapchat all the information is down below join our facebook group atd's for people um to get updates and to be connected with some awesome awesome filters and things what's happening yeah you can do that on live yeah that was just glow like a really weird haunted look anyways um so yeah I will see you guys tomorrow yep same time same place until then um be kind to one another you never know what someone's going through and we'll see y'all next time bye I said bye


We are talking about component matching of aircraft engines. We also talked a little about sizing of the engines. Today, we will look at what happens when you take an engine that has been designed very meticulously, components have been matched very meticulously and a certain amount of sizing has been done with reference to the design that has been done so that it can go on an aircraft. What we shall see today is when you have this kind of a complicated engine installed on an aircraft and flown, the performance of the engine does not quite match that of what has been designed for. The installed performance of an engine quite often comes out to be somewhat different and more often than not, it somewhat falls short of the requirement of flying of the aircraft satisfactorily. Now, this is a known phenomenon. This happens with civil aircraft engines which are meant for transport or passenger. This happens even more for military aircraft engines because there are number of issues here where the install performance of an engine quite often differs from that of a well designed engine. We have seen in the case when we were discussing very briefly about the sizing of the engine, the component that need to be sized to begin with the intake and the nozzle and we shall see today that after this sizing is done when the install performance is estimated or when an engine is flown they may need to be resized and this is something which needs to be estimated properly. Let us take a look at what are the issues involved. The engine design process using some of the theories that we have done in this lecture series, it sort of comes to an end with the sizing of the engine to achieve the design thrust and in the process of that we have arrived at a certain air flow, mass flow through the engine at the design point which matches that of that aircraft operation at that particular point. Once this is over we have some idea what the size of the engine and the geometry of the engine should be. So, accordingly when a power plant is installed or fitted to an aircraft and flown with it and this is often called the test flying of an engine. What happens is the installed thrust as experienced on board the aircraft comes out to be different from the designed uninstalled thrust. Now, this design uninstalled thrust may have been very meticulously computed or even been bench tested in a test bed for the isolated engine. Even after those procedures are over and one is satisfied that one is getting the design thrust, this still remains the uninstalled thrust. Once it is attached to the aircraft and flown with it, the test flying often reveals certain issues and as a result of it the uninstalled thrust often comes out to be different from the installed thrust. The different between this installed thrust T f and the uninstalled thrust which we have always called f is often quite significant. It is it could be significant at the design point and when it is flown we also get to know its performance at various off design points and as a result we shall see that they vary from one operating point to another of the engine or of the aircraft. If that is significant, if this difference is significant we need to understand that the aircraft will never be able to fly in its scheduled manner with this engine. In case of a military aircraft, this is quite catastrophic really because the military aircraft are designed for much more accurate flight spectrum and if the thrust fall short of the design thrust for the aircraft, the aircraft will never be able to carry out its mission. As a result of which a certain amount of estimation or understanding of what installed thrust is and what an overall installed performance of an engine is is required to be carried out before the engine is finalized and fabricated for flying. So let us take a look at some of the issues that are involved here. The uninstalled thrust or the thrust design thrust as we have called it before represents the results of the internal flow of air inside the engine. So all aspects of the internal flow of air and after it is mixed with fuel we often call it gas inside the engine through the various components of intake and compressor and then combustion chamber where fuel is added and then turbine and nozzle have been done in some detail in this lecture series. All of that put together gives us a reasonably accurate notion of what the design thrust would be. So what we see now is this design thrust is essentially an uninstalled thrust. The installing of the engine if it is mounted outside on the fuselage induces certain aerodynamic forces which we often called drag and this adds to the aircraft drag itself. So there is something like an engine drag which adds to the drag of the aircraft which the aircraft designer may have computed very meticulously and now this engine drag also comes into effect which means that the thrust that needs to be created now is not only to over crop the aircraft drag which we call here DAC but it has to also overcome its own drag which we call now D engine and this is the self drag of the engine and of course we are talking about external pod mounted engines. We shall see later on that engines that are mounted inside also have a few such issues involved. So what we see now is that the installed thrust must be the sum of the uninstalled thrust F and the self drag D engine and this D engine needs to be determined along with the initial engine size. So we have a sizing that has been done of the uninstalled engine what we shall see as we go along today is that the engine would probably need to be resized. Thus the very presence of the engine its inlet and nozzle which are the protruding elements or which are the covering of the engine and the exhaust stream that comes out from the back of the engine influence the flow over the entire aircraft depending on where the engine is actually mounted in the aircraft and it affects the instantaneous thrust or a momentary thrust at the time of its flying. So what we see now is number of issues are involved here which influences the instantaneous thrust created by the engine. So what we see now is that a number of issues where once the engine is mounted its physical presence on the aircraft create certain differences with the design thrust and hence the instantaneous thrust or the thrust obtained at the point of operation of the engine and the aircraft needs to be taken into account as far as possible for a possible resizing of the engine. We have seen in the in this lecture series that typically the modern aircraft engines specially the ones which are used for civil aircraft engines they often favor high bypass ratio. Now we have we have seen number of issues earlier in this lecture series that higher the bypass ratio lower is the specific fuel consumption and hence its economic to have high bypass ratio engines. Now it stands to reason that high bypass ratio engines would also have larger diameters and of course they would have resulting installation penalties that we are talking about now. These installation penalties we shall see that prevent the final benefits that means the benefits that you get from the high bypass ratio. So if you have larger diameters it stands reason that they will produce more of self drag or d engine and if you have more of d engine the engine itself would be called upon to create more thrust to overcome its own drag. So higher the bypass ratio higher is this particular issue of self drag and the need for creating more thrust by itself. Research has been done on this issue and it has been found that after a certain high bypass ratio an externally mounted engine reaches a certain point of diminishing return and there would be no point in increasing the bypass ratio any further. On the other hand if we have a fighter aircraft or a military aircraft where it is most likely the engine would be inside the fuselage of the aircraft the effect of installation would be somewhat different. We shall have a look at some of those issues where some of the effects of the installation would have some small adverse effect on the thrust creating capability of the engine. Now what the engine designer needs to do is he needs to have some idea about these installation effects and in which case he can then influence the design with this prior knowledge of the installation effect. He can go on to resize the engine and the installation penalties that we are talking about needs to be factored into the engine redesign and resizing. So what we see now is that a number of issues which would require the engine to be finally redesigned. Notably some of the component that we have talked about in the recent lectures the inlet and the nozzles and the corresponding exhaust flows these are the ones that affect the instantaneous thrust and these are the components which would probably need to be looked into a little more closely. We have talked about the fact that the inlet is quite often designed not only with reference to the engine but quite often with reference to the aircraft itself which means that if you have an engine used for different aircraft that aircraft may have a slightly different inlet or intake design. Now these are some of the issues that the engine designer would finally have to factor in to get his final engine design. Also there are issues here which are aerodynamic issues not only just geometrical reconfiguration. The inlet and the nozzle aerodynamics of the flow which is just before the inlet or just after coming out of the nozzle influence the thrust creating capability of the engine the net thrust. The net thrust that goes on to the effect of flying the aircraft. So, that net thrust gets affected by some aerodynamics that are happening in front of the inlet or intake and at the jet of the nozzle. Some of these need to be factored in with reference to the particular intake for a particular aircraft because some of these things are a little aircraft specific and not only engine specific. Let us take a look at some of these issues. The installed thrust that is available for flying now needs to be re estimated. Now that is going to be as we see here likely to be a little less than the so called design thrust that had been meticulously arrived at and this is factored in by a couple of parameters that we are introducing here. One is called phi inlet and other is called phi nozzle and these are what is called drag fractions that mean these are part of the drag created by the inlet and the nozzle and fractions of the design thrust the original design thrust and we shall see that if these are estimated or if these are made available or computable they would allow us to show that the design thrust often is fall short of the take off thrust or the necessary thrust of the engine that is required for the aircraft to fly and as a result of which the engine design thrust would need to be reconfigured to higher values and this higher value now factors in the drag fractions phi is the phi inlet and the phi nozzle. So, we need to we see that engine now needs to be redesigned with reference to a new engine design thrust otherwise it is going to fall short of the required thrust. If we look at the two drag fractions that have been introduced here it stands to reason that the true drag fractions the phi inlet and phi nozzle would vary with flight condition and throttle setting of any engine and it varies from aircraft to aircraft slightly even for the same engine and this is what we are talking about that if you put let us say the same engine on two different aircraft you would invariably get two different installed thrust requirements because the phi inlet specifically phi inlet and may be even phi nozzle will vary from one aircraft to another for the same engine. So, we need to figure out a means of computing phi inlet and phi nozzle as a function of flight conditions. Now, flight conditions include the altitude at which the aircraft is flying the attitude at which their craft is flying which means it may be a climbing flight and not necessarily a cruise straight level flight and the velocity at which it is flying. The altitude of course would give us the pressure and temperature at that altitude and in addition to the flight conditions we would need the throttle settings of the engine that means the throttle setting that is exercised by throttling the nozzle of the engines typically and these are the parameters that would influence phi inlet and phi nozzle and many of these parameters are with reference to what we have been calling off design condition of the engine and now we see now that many of these off design conditions refer not only to the off design of the engine but they often refer to off design of the aircraft. So, as we see now when we are trying to figure out the uninstalled thrust with reference to uninstall thrust it is not only the engine but often the aircraft is also coming into the picture and the resizing that needs to be done now factors in the various flight conditions of the aircraft. So, we need to figure out the flight conditions of the aircraft we need to figure out the throttle settings of the engine and then find the install thrust so that we can resize the engine. The number of things that need to be done is we start we have started with a design point we first what did we do we first figured out what the design point is what the design point thrust requirement is we try to design the components of the engine with reference to the so called design point we match the components with reference to the design point and we size the engine with reference to the design point. And after doing all this when we try to put the craft and the engine together we find that the whole engine needs to be slightly resized this needs to be done because as I mentioned earlier there is quite often a significant difference between the installed thrust and uninstalled thrust and as far as possible this needs to be met before the engine and aircraft actually starts flying on a regular basis. Each critical flight condition needs to be found out now some of the critical flight conditions of course we know the takeoff condition the climb condition if there are maneuvers necessary for military aircraft we need to factor them in where there are dives and pullouts and those are the conditions at which the engine needs to be resized till we get the maximum power or the thrust in accordance with the requirement of the engine of the aircraft. Our final goal is to make an aircraft fly to its mission to its actual purpose and to do that it is necessary that the engine itself is very finely tuned to the needs of the aircraft. One of the first things when we need to look at is what is the amount of air flow that is going inside the engine because that is what makes the thrust air flow that goes inside the engine is the working medium through which the thrust is produced. So the first thing we need to ensure is that the engine air mass flow is what is going inside the engine and there is no mismatch between what is required to create the necessary thrust and what is available for creating the thrust. So there is a difference between requirement and availability needs to be looked at very closely and this needs to be done under all flight conditions and that is the important issue. If you put a engine which has been designed meticulously at a design point and fly it with an aircraft whether it meets all the flight conditions needs to be looked at very closely because under all flight conditions it should match the thrust requirement otherwise one or the other flight condition will not be performed according to the design of the aircraft. So if the engine does not create the necessary amount of installed thrust with the aircraft the aircraft itself will fall short of its performance requirement of its own design. So these are the issues that we need to look at very closely. Let us move forward and look at some of the issues. The first thing as I mentioned we need to look at what is the mass flow of air that is going inside. So if we look at the mass flow of the air we see that it gets slightly redesigned or reconfigured with the change of the requirement of thrust from F to T F that is from design thrust to the installed thrust. And here the phi inlet and phi nozzle the two drag fractions have been now factored in and having factored them in we get a new mass flow that needs to be allowed inside the engine. Now this needs to be done for each flight condition. If we take a climbing and accelerating flight as a general description of a flight condition or generalized description flight condition m dot naught that is the mass flow through the engine can be written down in terms of the weight of the aircraft, the instantaneous weight of the aircraft, the drag of the aircraft, the drag of the engine, the velocity of the aircraft and the engine and the height at which the altitude at which it is flying or if it is experiencing a climbing flight and then of course the drag fractions that we have defined and introduced just a little while earlier. Now in order to find each of the flight condition which of them is most demanding is needed to be found out a priority as early as possible. So, each of these mass flow condition needs to be multiplied by a relevant m dot design by m dot of design because most of the flight conditions are indeed of design only one of them is a design point and hence all those flight conditions which we are considering would have such a mass flow ratio of design to of design and this can be obtained from the detailed engine of design calculations. We have done this before and the engine of design calculations need to be brought forth again for the purpose of estimating the install performance. The highest of these the largest product which corresponds to the largest design of the engine now comes out to be the required engine size. So, if you create an engine to meet the maximum performance that would be the largest size of the engine and would be required for flying the particular aircraft. The question is whether this largest size of the engine is what you would like to have on one hand if you do not have that size of the engine you do not get the thrust which is required at the most demanding flight condition. On the other hand at many other off design operating conditions you probably do not need that large engine. So, this is where the decision needs to be taken whether the demanding condition is very critical demanding condition if it is you would need to then go for that engine and then of course, under off design conditions you need to throttle down the engine bring down the rotating speed of the rotating components. So, that engine gives you lesser amount of thrust with the same big sized engine. So, the resizing of the engine that we are talking about now comes out of the most demanding condition of the flight as it is installed on an aircraft. What happens is as I was saying this resized engine could very well be a little too large for all flight conditions and hence the performance at other conditions quite often is obtained by throttling the engine which is the mass flow is brought down to lower values. Then you can bring down the turbine entry temperature then you can bring down the nozzle temperature if it is an after burning engine you may like to switch off the after burner and until a new installed thrust is arrived at for flying the aircraft at that particular operating aircraft flying condition. Now, this process needs to be done meticulously before the installed behavior of the engine or the installed thrust and its instant instantaneous fuel consumption rate is known with certain amount of accuracy. So, the installed behavior of the engine includes installed thrust and installed fuel consumption rate and this needs to be found out as accurately as possible. So, that you can have a close matching between the engine and the aircraft. Let us take a look at some of the factors that govern the installed engine. When an air is entering an intake if we consider to begin with a subsonic intake even before the air has entered the intake because of the shape of the stream tube that it automatically takes before it enters the intake. The pressure that is shown here acting as P external minus P naught P naught being the pressure inside the stream tube and this is quite often called the over pressure on the flow that is coming into the intake. This because of the shape of this stream tube that it has automatically taken shape it often means that if you integrate the all the over pressure over this shape of the stream tube you would probably get a drag or a force which is acting in the direction parallel to the axis of the engine and this is often an additional drag which comes out due to the over pressure of the stream tube that it automatically takes shape. Now, this is typically what we are seeing is a typical situation that happens probably during straight and level flight during cruise, during take off and many other operating conditions. The stream tube that it takes quite often could be extremely different quite different from this and under certain situations for example, during take off the flow coming in would be accelerating flow and would not be slightly diverging or diffusing flow as we see here and in that situation the problems that are encountered by the intake system is quite different from what we are looking at right now. So, right now we are looking at a straight and level flight during which it looks that if the stream tube takes this kind of a shape in which as we see now a 0 the far upstream tube diameter or area is slightly less than that of at the intake phase you would end up getting a drag which is known as additive drag. Now, if we try to factor in this additive drag we can talk in terms of the parameters that the stream tube typically experiences the pressures P 0 and P 1 the areas A 0 and A 1 and of course, the Mach numbers at station 0 and 1 and we can figure out at least theoretically a reasonable idea or notion of what this additive drag is going to be and the point is this additive drag is happening even before the flow has entered the engine. You have done in great detail what happens inside the intake what happens in other components of the engine, but this is happening outside the intake even before the flow has gone in. The aircraft engine combined is experiencing an additive drag. So, the inlet drag fraction now takes another shape that the additive drag essentially creates the inlet drag fraction. This can now be written down as we have been doing with reference to the fundamental parameters the two Mach numbers the temperatures and the areas and the pressures at these stations before the intake system. Now, this can be evaluated for any given set of values for M naught, M 1, A naught which is the sonic velocity and the thrust by mass flow that is specific thrust as we have called it earlier. Now, these are the issues that finally, determine what the inlet drag fraction is going to be and as we see this is happening before the flow actually even enters the intake. If we try to plot this inlet drag fraction with reference to the two important parameters the Mach number upstream and the Mach number at the inlet phase. We see a typical pattern that emerges from which the inlet drag fraction can be computed a priori which means if the two Mach numbers available from the theory that we have established a certain inlet drag fraction can be computed or found out and this can be factored into the installation of the engine. So, what we learn from this intake installation is that the drag fraction phi inlet is not very large if M naught is almost equal to M 1 and that the entering stream tube experiences no change in flow area that is A naught is equal to A 1. In such a situation as we have seen before it stands to reason if we look at the earlier diagram that if A naught is equal to A 1 this shape is going to be a cylindrical flat cylindrical shape and hence the installation drag would essentially be 0 or pretty close to 0. The other thing is that the usual range of subsonic flight which is a normally of the order of 0.8 the value of M 1 that is at the inlet phase or intake phase is often of the order of 0.4 to 0.6 which means a certain amount of pre diffusion we for may call it before it enters the intake may be allowed to happen. The high values of phi inlet occur at mark number 0 that is at takeoff and it is in the range of 0.5 to 1. Now, as we have seen this is not due to the diffusive flow that we have seen in the picture, but it is due to highly accelerating flow that enters the engine from all sides to cater to the engine mass flow requirement and in the process it creates a very large phi inlet during the process of takeoff. So, these are the issues that the engine designer would need to reconsider to create a engine that meets its installed thrust requirement as closely as possible. Let us take a look at what happens when you have a supersonic intake. The inlet drag fraction that we have been talking about for supersonic inlet can be estimated from the momentum change that takes place due to the bypass and the bleed. Now, these bleeds we know and you have done in case in your lecture series that these are often required for various engine purposes and when all these are factored in certain amount of supersonic inlet drag essentially comes through which needs to be factored into the resizing of the engine and essentially other things that come out of the installed engine performance. Now, as we see here a typical supersonic inlet flow model would give you at least one oblique shock and then you might have a boundary layer bleed to control the inlet flow and then you may have a bypass or a bleed which may be required for engine servicing or many other purposes within the engine or the aircraft and one of the bleeds may be occurring during the flow inside the intake which is supersonic. The other of the bleed may be occurring when the flow inside the intake is actually subsonic. Now, if these bleeds are essentially being made to control the mass flow through the intake and through the engine they would entail certain amount of drag penalty when they come out from the size sides of the engines and these are the drag penalties that need to be factored into resizing of the engine because these drags would bring down your thrust calculation and hence the installed thrust would be less than that of the design thrust. The typical supersonic drag fraction inlet drag fraction can be written down again in terms of the areas that we have looked at the Mach number and of course, the A 0 or the local supersonic speed of the flight. Now, once this value of A 1 has been selected the intake area we can use this theoretical derived equation directly into evaluation for any flight condition what the drag fraction should be. So, once the flight condition is known that is the atmospheric pressure temperature and Mach number and the engine throttle setting or power setting that is the area of the intake and the thrust setting we can find out what the drag fraction for this condition flight condition and engine condition could possibly be and this theoretical finding can be factored into the inlet redesign or resizing. Now, what we see here that when this drag fraction approaches a value it approaches a value 0 when M naught approaches unity which is the sonic speed or when A naught approaches A 1 which is the sized value. So, which means that the drag fraction phi inlet can be useful when it is evaluated far from both those conditions at these conditions the phi inlet is likely to be theoretically determined to be 0. So, under those conditions the drag fraction ending could be a little misleading for installed thrust creation. So, at other off design operating conditions the drag fraction that one gets out of this theory is likely to be reasonably accurate for installed performance evaluation. If we now look at the contribution of the exhaust nozzle to the installed thrust re-estimation we see that a typical exhaust nozzle would have a certain contour you have done in great detail what is happening inside the nozzle. We will take a look at what is happening outside the nozzle on the outer surface of the nozzle because for an engine to be created we need to know what is the shape and dimension of the nozzle external surface and we see here we need to figure out what the value of A 10 should be and what the value of A 9 should be because that is where the nozzle gets shaped and then of course, what the length of the nozzle should be and if we try to find out all that what happens is under certain conditions these nozzles would create what is known as pressure drag under either supersonic or subsonic flight conditions and one of the methods by which this shaping can be created is through a parameter called integral mean slope which essentially defines the shape of the nozzle. Now, this integral mean slope can be defined in terms of an equation which essentially takes into account the areas we are talking about and the radii we were talking about and the length A is the area at any point on the intake length and the integral mean slope can be found at any point on this intake shape. So, A is at any point on the intake shape and this can be the integral mean slope over here can be found using the simple definition that we have put down here. For a very quick practical solution quite often integral mean slope can be written down in terms of the diameters and the length that one is conceiving and it gives a first cut notion of what the integral mean slope is should be. If we put this integral mean slope as one of the important parameters what we see here is that the drag that is created by this nozzle shaping can be connected to the integral mean slope or IMS and it is dependent on the shape of the outer shape of the nozzle. Now, the number of nozzle shapes have been factored in here we can have a rounded corner or we can have a sharp corner and the plots have been created here for sharp and rounded corner. The sharp corners are once with filled out symbols and the rounded corners are once with hollow symbols and we can see here what stands to common sense that the rounded corners would have lower drags and the sharp corners would have higher drags under different kinds of IMS values. Now, sharp corner is something which is obviously then an avoidable thing and if you have to create a rounded corner and then the question is we have certain values of small d by d which is the area ratio between the exhaust and the supply first area from which the flow ensues from the into the nozzle and this diameter ratio is one of the parameters that come out as an important issue in figuring out what the nozzle shape should be. If we now look at the rounded shapes we realize the rounded shape is better than the sharp shape there are various ways the rounded shape can be factored in and again if we look at the d by d ratio and factor that with the x by l there are number of rounded shapes n is the parameter here which is been plotted here and one can find out what the shape should be and then one can find out what the nozzle installation penalty can be from this computation. Now, these are the issues that engine designer would typically need to be aware of he needs to factor in what the nozzle external shape should be and then he needs to figure out what the nozzle external shape should be if it is rounded shape which here has been shown in terms of the values of a parameter n which comes out in the diameter ratio and if this is available then we can figure out what the nozzle drag penalty is going to be and then that gives us the nozzle drag fraction which can be then factored into the reconfiguration of the installed thrust of the engine this gives us this puts us together theoretical method of estimation of the nozzle drag fraction for a a priori estimation of the installed thrust. We will put together all these things in the nozzle and in intake resizing which then tells us that if we do all this the engine would need to be resized and the resized engine would eventually meet the thrust requirement of the aircraft under various flight conditions and as we see the thrust requirement needs to be met under various flight conditions and under various engine throttle conditions. If we put them all together and we put together the simple theory that we have introduced in this lecture it gives us an a priori notion of what the installed thrust reconfiguration would require and what the engine resizing needs to be done so that it meets the installed thrust under all flying conditions of the aircraft. In the next lecture we will take a look at some of these theories that we have done over the last three or four lectures and try to see whether some of these theories can be utilized to solve some practical problems that are typical to aircraft engine matching. So, in the next class we will try to solve some practical problems from with reference to aircraft engine matching.