Awesome content... Wish he uploaded more.... I wanna buy his flight computer but for $300 ill go without 😂 there's a few other channels that are gonna smoke him on his own challenge.
@@221b-l3t Nah. As much he's havign fun with what he does, he's only doing advanced model rocket powered by solid fuel (so overall his rockets are "just" boosters ) The first private citizens to reach orbit would be the team of Copenhague suborbital, they have much more advanced and bigger rocket using ethalox and have pretty good plans on what could be the final rocket.
@@ballom29 People have reached orbit with pretty small solid rockets. JAXA put a 9 pound microsat into orbit on top of a modified S-520 sounding rocket with a third stage.
You represent all these topics perfectly, and thats why you are my favorite TH-camr to go to for space. Thank you for being this awesome and keep it up
Been watching your channel for a bit now, and while neither an engineer or scientist, I do enjoy your channel. You keep it informative all the while engaging with your audience though humour. Keep up the good work!
@@dwightk.schrute6743 Has to be the cape in Florida. Probably a manned capsule will never fly from the west coast just because of the available orbits from there. You can't really get to the ISS from Vandenberg.
@@williamgreene4834 Well, originally they were planning to use the same capsule from the pad abort, and do the in-flight abort at Vandenberg. I dunno why and when they changed it, but it's definitely happening at the Cape now.
_"It's like cars! Fins make it go faster!"_ Actually that is not the case at all. Fins increase aerodynamic surface area which in turn creates more aerodynamic drag. In the late 1940s and throughout the 1950s, auto makers around the world - Ford, Chevrolet, Dodge, Mercedes-Benz et al - all toyed with having fins on the trailing quarter panels of their cars - the Cadillac Eldorado was the first to use them in excessive styling. In the end, even in minor aesthetic form, they were found to cause more harm to the vehicle's handling stability at high speed than improve safety - a relatively low velocity crosswind on a high-speed motorway ( 100+ km /h [75+ mph]) was enough to cause the vehicle tail to suddenly swerve and to a inattentive drivers of the day (which amounted to essentially everyone who drove on the roads back in the 1950s into the 1970s ), this was an accident waiting to happen. Remember all MVs back then were rear-wheel drive, and if the drive wheels (thrust) were thrown out of alignment with the direction of travel, the result could be catastrophic for the occupants of the vehicle. This was a serious injury liability potential to the auto makers. One they did not want to pay for. It's why you don't see them today. Fins may have made cars look cool and futuristic, but it also made them more deadlier than they already were.
You weren't wrong during the (yet again) scrubbed Delta 4 launch livestream when you said you had a surprise video for us! Really like when you do comparisons in Kerbal Space Program! Glad you do your homework and give us quality videos!
I couldn’t agree more! The time and effort you put in to your videos, Tim, is amazing!!! I love everything about this video! Very well done from a huge fan!
What I really love about SpaceX is that a video about them that is a year old is OLD. Even though this one still holds up. They progress so fast that a year makes a big change. 2021 is going to be exciting, either a huge disaster or great leaps forward.
they could use the booster that recently landed in water with only minor damage for the in flight abort as they cant use it for commercial missions anymore so there would be nearly no losses to detonate the booster and just in case the booster does actually fail the test would still be successful just the abort happening earlier in the mission
@@fredericvadez7998 Wouldn't work, since NASA standards say a rocket has to safely fly 7 times or so unchanged to pass for manned rating. If they used a Block 4 it wouldn't be representative of a Block 5.
I doubt it will actually be used again. Elon tweeted out the internal usage statement before he knew the true condition of the booster. If you watch the recovery videos it's all bent up. I'm sure they're going to use the fins in the landing legs and it's here and there but the main tube of the rocket fuselages is toast
Really looking forward to what India is doing with their manned and unmanned space program. Be good to have another nation with more presence in space.
@@krisdevalle yeah indeed! That's how we are all together as a spiceis in 1⃣ direction without any doubts or filters if u know what I mean.... Isro always comes up with their own challenges and it's Great to watch them accomplishem each time.... Sounds good.... Good to hear from you also :) Thank you! We can definitely talk (Dm) for further healthy talks together. 😊
7:23 I like how Tim decided to use the Thud engines to represent superdraco motors when he has a mod that adds superdraco motors. You can even see the part at the bottom of the screen. I think he just forgot that he had that.
Just found this channel. Watched my first SpaceX launch live from the Cape a few weeks back and boy have I caught the bug! Loving this channel to keep me in the loop!
10:17 No, when the center of lift is under the center of mass, the craft can be stable. However it has to get wings or fins to stabalize using aerodynamics. The first craft clearly did not have fins so the center of lift cannot form a straight line with the ground, then the center of lift will cycle upward and downward because of no fins or wings to control the craft in any sort of way. Therefore the cycle continues and the craft spins as shown. The reason why they have to extend a part to add fins is because the crew capsule is designed to flip and any sort of fins cannot achieve that balance because the capsule would like to flip and then any thrust will be unstable. The reason I can think of not adding grid fins is because it makes the crew capsule less aerodynamic though I can't see why they won't do that. Maybe they want to maintain the beauty of the capsule. After all, they designed the craft for us to see.
Tim, isn't it called Center of Pressure? I think Center of Lift is more of a KSP thing, or is it a synonym? ;D Interesting topic and cool video nonetheless!
DrGraypFroot Yeah, I think "center of pressure" or "aerodynamic center" would be more general, as lift is an aerodynamic force in a particular direction. Technically, though, the center of pressure or aerodynamic center is the point at which all aerodynamic forces can be resolved into a single vector, so they would be at the same location.
@@brainmind4070 Not entirely true. Center of pressure and aerodynamic center are two different things. Center of pressure is the point, where the sum of a pressure field acts on a body (eg. where the force is concentrated), the aerodynamic center on the other hand is the point where the rotational moment does not change, regardless of the angle of attack (pivot point). Never heard center of lift before though other than from KSP..
Wish you'd mentioned spin testing apropos model rockets. It makes the concept clear to everyone. If you spin it and the front doesn't point forward you need a redesign. Then you could show the same with spin testing a reentry module, only in reverse. It's such a basic easy thing that can't lie.
I remember the first Dragon Abort Test. Of course, it being unmanned meant that it didn't necessarily need extra stability. As the Dragon 2 will be manned. It needs a higher degree of safety. So the fins make sense. Great content as always Tim. Blue Origin's New Shepherd Capsule. Isn't the right shape for fins. Grid Fins might be okay though. I'm not a designer. So don't really know how feasible they are.
Now can you mod Kerbal to add differential thrust? An active system to stabilize the capsule during abort, no truck and no fins. The reason is Dragon was originally intended for the Moon. To return from the Moon, it required a service module. I was modified to service ISS only, the service module was replaced with a trunk that holds solar panels and acts as a spacecraft adapter for the Falcon 9 rocket. But to use Dragon to go to the Moon, it will need some way of returning from Lunar orbit. That means adding propellant tanks and engine(s) to the service module for TEI. Once you add that mass, pad abort engines will not longer be able to drag the service module with it. This will require the capsule to abort without any sort of trunk. So again, demonstrate active differential thrust to maintain orientation just long enough for abort.
Haven't tried anything like that in KSP for a long time, but many revs ago adding fins to an upper stage was a disaster waiting to happen, and not waiting long, either. By adding fins to an upper stage, you're moving your CoL forward, at least until such time as you jettison the lower stage. Add to that the stability control loop delay plus the noodle joints, and you'd be in for a hysterical (in all senses of the word--funny, terrifying, and organ-displacing) time.
In everyday general aviation, pilots must consider weight and balance calculations before they take off. The center of lift is mostly fixed in a certain position. But the center of gravity (CG) can be shifted depending on where we place the heavier passengers and our baggage and fuel. The greater the distance between the CG and the CL, the more stable the aircraft becomes. When the CL is behind the CG we call it positive stability. That means that if the airplane is flying straight and level in a normal cruise configuration and you upset the cruise, for example by pulling back on the stick and letting it go, the airplane will oscillate into a waveform and return to normal straight and level flight. That is called "positive stability'. That's a good thing. However, if the pilot misloads the airplane and places the GC at or near the CL, and upsets the cruise configuration, the aircraft will go into continuous oscillation and its waves will continue as usual. This is called "neutral stability". BTW, some military jets that "fly by wire" are designed for "neutral stability" because of aircraft will maneuver more readily. Safety is conserved by the "fly by wire" computers. The worst way to misload an airplane to put the CG behind the CL. If you upset the cruise by pulling back on the stick or control wheel, the oscillations will continue to grow in wave height. This is called "negative Stability". No pilot want's to be in a negatively stable condition if he/she enters a stall because it might be impossible to recover from such an upset. Just a little basic aerodynamics 101 for review. So the next time you get into a small airplane, don't be upset if the pilot asks you how much you weight and wants you to sit in any particular seat in the airplane. Even in a lightly loaded airline jet, the crew may ask passengers to move their seat, for weight and balance purposes.
I have a rocket motor for the top of landers, a toroidal sheath motor designed to leverage the gases as an atmosphere for lift on top of the thrust vector, a thust-lift design the nacelle shaped gives lift and it needs fins to not spin, and to cool flow raising density and thickening the boundary-layer for lift power. Works in a vacuum, things point to having them on payloads to stabilize on takeoff before it has momentum, and reduce the max pressure reached. Cheers, tom
Tun, another really good video. You, along with Amy at Vintage Space, Scott Manley and Curious Droid have become my main source for space news, and increasingly your content has been among the top even in that group. Good stuff!
🙏🙏🙏 wow that’s huge praise! Thank you!!! I greatly admire all those channels and people, so that means a lot. Amy is great. I can’t wait for her new book to be done so she can get back to TH-cam!!!
I really enjoy your channel. Your launch live streams are great. I have totally gotten into rockets because of watching your content. Thanks for all your work!
Since nobody seems to have mentioned this in the first 100 or so comments... notice the clip of an Apollo abort test that starts just before the 3 minute mark. No fins. How do they keep it from turning around? I suppose it's one of two things--possibly those smaller motors at the top of the escape rocket are correcting for the capsule's desire to go flat-end-first... or, possibly, the presence of the escape tower renders the assembly stable. I recall from my model rocket days that a cone's center of pressure (the term we used in those days, side-stepping the question of whether it's more accurately called center of drag or center of lift) is two-thirds of the way back from the point to the base. And that's why the capsule wants to go blunt-end-first: unless it's got some serious ballast in the pointy end, a cone's center of mass is going to be a lot closer to the base of the cone than that. Did the Apollo's big heavy escape-rocket tower, well forward of the conical capsule, move the center of mass far enough forward for the assembly to be stable?
The video is not right. There are important 3 centers on the rocket: center of mass (abbreviated COM or CoM), center of thrust (COT), and the center of lift (COL). If the center of thrust (defined by position of engine nozzles) is above center of gravity and center of lift, then it doesn't matter if center of lift is even above the center of mass. That is why Mercury or Apollo capsules with escape engine tower high above the capsule did not need any fins when escaping away from exploding rocket , even when both had center of lift above the center of mass.
Center of mass, center of thrust and center of drag. A dart works as the center of mass is in front of the center of drag. Fins on a rocket keep the center of drag behind the center of mass.
The Crew Dragon fins will push the center of lift quite a way forwards on the Falcon 9 rocket. I hope they have enough gimbal authority to keep the whole vehicle stable. They probably simmed it a lot.
bingo. I'm not a rocket scientist but have built and flown many a model rocket and if you don't get that relationship correct (CG to CP), you have what is known as "an interesting flight"!!! And if your model was built from a kit, when it hits the ground it is said to be "re-kitted". His first demo here was a "re-kit" for sure!!
There are 3 centers important on the rocket: center of mass (abbreviated COM or CoM), center of thrust (COT), and the center of lift (COL). If the center of thrust (defined by position of engine nozzles) is above center of gravity and center of lift, then it doesn't matter if center of lift is even above the center of mass. That is why Mercury or Apollo capsules with escape engine tower high above the capsule did not need any fins when escaping away from exploding rocket , even when both had center of lift above the center of mass.
It’s probably to verify that the abort system can both detect a problem _and react to it_ in time to save the crew. It doesn’t do any good for the abort system fire if half the capsule has already been destroyed.
www.faa.gov/about/office_org/headquarters_offices/ast/environmental/nepa_docs/review/launch/media/Draft_EA_for_SpaceX_In-flight_Dragon_Abort_508.pdf the booster is going to shut down its engines, effectively, without telling Dragon about it, so Dragon will think there's something wrong and abort immediately. The report there says the booster is expected to break up, and that they've designed the dummy 2nd stage to facilitate burning of the fuel.
Kerbal is just the best for intuitioning spaceflight. If you don't have it, get it! You will see the world differently after a few hundred hours of kerbal.
Inflatable fins (think marriage of airbag with 747 escape chute) might make even more sense. Compact, lightweight, instantly deployable, no/minimal control surfaces. They'd give you the desired drag and slipstream without weighing tons during ascent.
I recently saw a shooting video using a standard air rifle pellet shape of various sizes used with and without spin to stabilize it and it seems to fly true fired backward as well as forwards, it seems a bullet with a waist and hollow skirt is an ideal shape facing either way.
Thanks for a very informative video! Wondered about the fins myself. Excuse me if the answers are on the surface, but my questions are related to the strange design of the solar panels on Dragon 2: 1) how come they won't be damaged during the ascent? 2) why SpaceX decided to go with unmovable panels in the first place? 3) Are there solar panels on Starliner and if yes, where, if no, how limited its batteries?
"they are going to explode the falcon 9 beneath it"
Maybe Elon wanted to see something explode, and when falcon heavy didn't he planned this.
important for testing, but bad for PR and marketing for folks to get in it :D
4:32 Everyday Astronaut: *"A vehicle that could use fins of some kind is Blue Origin's Shepard"*
*_Jeff Bezos is typing_*
Jeff Who?
Wasn't that the guy from "Full House?"
I think Blue Origins Shepard is ugly
@@mz00956 It suffers from over compensatious.
@@mz00956 it look like a .....
You've been totally on fire with the meaty educational content videos lately, I'm loving it.
Thanks ...
BPS is such an amazing and underrated channel, nice that you gave him a shoutout
Yep
Agreed
Awesome content... Wish he uploaded more.... I wanna buy his flight computer but for $300 ill go without 😂 there's a few other channels that are gonna smoke him on his own challenge.
A model rocket with a gimbal?!?! Now that's a dedicated hobbyist.
Glad to see BPS.space getting much needed attention
Yes
Wouldn't be surprised if that guy becomes the first private citizen to reach orbit.
@@221b-l3t Nah.
As much he's havign fun with what he does, he's only doing advanced model rocket powered by solid fuel (so overall his rockets are "just" boosters )
The first private citizens to reach orbit would be the team of Copenhague suborbital, they have much more advanced and bigger rocket using ethalox and have pretty good plans on what could be the final rocket.
@@221b-l3t me neither
@@ballom29 People have reached orbit with pretty small solid rockets. JAXA put a 9 pound microsat into orbit on top of a modified S-520 sounding rocket with a third stage.
You represent all these topics perfectly, and thats why you are my favorite TH-camr to go to for space. Thank you for being this awesome and keep it up
Great video! Appreciate all the hard work you do to make these high quality videos.
what impresses me the most about the Dragon capsule is that finally we get a spacecraft that doesn't look like a modified garbage can.
So it can flex on the other capsules
Been watching your channel for a bit now, and while neither an engineer or scientist, I do enjoy your channel. You keep it informative all the while engaging with your audience though humour. Keep up the good work!
I was thinking about BPS.space when you were talking about fins...
Bps.space just posted
Is it just me or does Joe look quite a lot like a young Elon? Hmmm...😕
I came here right after watching their post
Thats why North Korea use such components
Merry Christmas *everybody*
You too!
Great video! I can´t wait for the falcon 9 explosion xD
Where is it launching from?
@@dwightk.schrute6743 Has to be the cape in Florida. Probably a manned capsule will never fly from the west coast just because of the available orbits from there. You can't really get to the ISS from Vandenberg.
@@williamgreene4834 Maybe, but they're not trying to reach leo. Its just a test of the escape system. I've seen Falcon 9's launch from vandenburg.
@@williamgreene4834 Well, originally they were planning to use the same capsule from the pad abort, and do the in-flight abort at Vandenberg. I dunno why and when they changed it, but it's definitely happening at the Cape now.
@@dwightk.schrute6743 Yes they have, I'm just saying they will probably not launch humans from there because of the orbits available.
As always an audible pleasure to watch and listen.
Best video on TH-cam to explain why most rockets have fins
It's like cars! Fins make it go faster!
And Spoilers!
Don't forget about the NOS stickers.
And flames! Oh wait. OK pin stripes.
yeah, Chrysler figured this all out in 19 freaking 57!!! :D
_"It's like cars! Fins make it go faster!"_
Actually that is not the case at all. Fins increase aerodynamic surface area which in turn creates more aerodynamic drag.
In the late 1940s and throughout the 1950s, auto makers around the world - Ford, Chevrolet, Dodge, Mercedes-Benz et al - all toyed with having fins on the trailing quarter panels of their cars - the Cadillac Eldorado was the first to use them in excessive styling.
In the end, even in minor aesthetic form, they were found to cause more harm to the vehicle's handling stability at high speed than improve safety - a relatively low velocity crosswind on a high-speed motorway ( 100+ km /h [75+ mph]) was enough to cause the vehicle tail to suddenly swerve and to a inattentive drivers of the day (which amounted to essentially everyone who drove on the roads back in the 1950s into the 1970s ), this was an accident waiting to happen. Remember all MVs back then were rear-wheel drive, and if the drive wheels (thrust) were thrown out of alignment with the direction of travel, the result could be catastrophic for the occupants of the vehicle. This was a serious injury liability potential to the auto makers. One they did not want to pay for.
It's why you don't see them today.
Fins may have made cars look cool and futuristic, but it also made them more deadlier than they already were.
You weren't wrong during the (yet again) scrubbed Delta 4 launch livestream when you said you had a surprise video for us! Really like when you do comparisons in Kerbal Space Program! Glad you do your homework and give us quality videos!
I couldn’t agree more! The time and effort you put in to your videos, Tim, is amazing!!! I love everything about this video! Very well done from a huge fan!
Not sure if I ever told you how awesome your channel is.
Your channel is awesome.
What I really love about SpaceX is that a video about them that is a year old is OLD. Even though this one still holds up. They progress so fast that a year makes a big change. 2021 is going to be exciting, either a huge disaster or great leaps forward.
That side-by-side was ace!
The fins (as well as the surface area of Crew Dragon's trunk) are also used for solar power cells on one side, and heat radiators on the other side.
they could use the booster that recently landed in water with only minor damage for the in flight abort as they cant use it for commercial missions anymore so there would be nearly no losses to detonate the booster and just in case the booster does actually fail the test would still be successful just the abort happening earlier in the mission
That booster is scrap metal now
@@cazymike87 no, as they said they are saving it for an internal mission, most likely this one, as it did a soft water landing.
Seems like they will use an old flight proven block 4...
@@fredericvadez7998 Wouldn't work, since NASA standards say a rocket has to safely fly 7 times or so unchanged to pass for manned rating. If they used a Block 4 it wouldn't be representative of a Block 5.
I doubt it will actually be used again. Elon tweeted out the internal usage statement before he knew the true condition of the booster. If you watch the recovery videos it's all bent up. I'm sure they're going to use the fins in the landing legs and it's here and there but the main tube of the rocket fuselages is toast
Thank you for mentioning ISRO! 😊
Really looking forward to what India is doing with their manned and unmanned space program. Be good to have another nation with more presence in space.
@@krisdevalle yeah indeed! That's how we are all together as a spiceis in 1⃣ direction without any doubts or filters if u know what I mean.... Isro always comes up with their own challenges and it's Great to watch them accomplishem each time.... Sounds good.... Good to hear from you also :) Thank you! We can definitely talk (Dm) for further healthy talks together. 😊
7:23 I like how Tim decided to use the Thud engines to represent superdraco motors when he has a mod that adds superdraco motors. You can even see the part at the bottom of the screen. I think he just forgot that he had that.
Just found this channel. Watched my first SpaceX launch live from the Cape a few weeks back and boy have I caught the bug! Loving this channel to keep me in the loop!
10:17 No, when the center of lift is under the center of mass, the craft can be stable. However it has to get wings or fins to stabalize using aerodynamics. The first craft clearly did not have fins so the center of lift cannot form a straight line with the ground, then the center of lift will cycle upward and downward because of no fins or wings to control the craft in any sort of way. Therefore the cycle continues and the craft spins as shown.
The reason why they have to extend a part to add fins is because the crew capsule is designed to flip and any sort of fins cannot achieve that balance because the capsule would like to flip and then any thrust will be unstable. The reason I can think of not adding grid fins is because it makes the crew capsule less aerodynamic though I can't see why they won't do that. Maybe they want to maintain the beauty of the capsule. After all, they designed the craft for us to see.
6:04 : YES!!! I always wondered if they would!
That's going to be the awesomest (intentional) firework ever!
Hey! Love both you and Joe B! I try to express what I learn on your channel through techniques from Joe's channel.
Tim Astronaut the Everyday Dodd
I've had ur music stuck in my head waking up in the morning after long night rocket streams
Great video. Neatly explained. Please do more of these!
good basic "rocket science" for the none scientist!!
Love your vids want to be rocket engineer when I grow up you teach me a lot
i loved the side by side with spacex and kerbal
Dude. Love your music. Just found you on Spotify. You've definitely got whatever "it" is and I thank you for putting it out there. Subbed.
Fantastic expansion Tim!!!
I love your original music! Especially how you add it as your background soundtrack/score!
Tim, isn't it called Center of Pressure? I think Center of Lift is more of a KSP thing, or is it a synonym? ;D Interesting topic and cool video nonetheless!
DrGraypFroot Yeah, I think "center of pressure" or "aerodynamic center" would be more general, as lift is an aerodynamic force in a particular direction. Technically, though, the center of pressure or aerodynamic center is the point at which all aerodynamic forces can be resolved into a single vector, so they would be at the same location.
@@brainmind4070 Not entirely true. Center of pressure and aerodynamic center are two different things. Center of pressure is the point, where the sum of a pressure field acts on a body (eg. where the force is concentrated), the aerodynamic center on the other hand is the point where the rotational moment does not change, regardless of the angle of attack (pivot point). Never heard center of lift before though other than from KSP..
DrGraypFroot You're right. My aerodynamics is rusty.
@@brainmind4070 We're all here to learn :) and I'm no scientist either ;)
DrGraypFroot I aced fluid mechanics and aerodynamics in college, but alas, it has been awhile since I've delved into such concepts.
I'm surprised I don't study basic Physics like this in high school.. Thanks Tim!
Very, very cool explanation, sir!
love the explanations ... Wish youtube was a thing when I was in school
Wish you'd mentioned spin testing apropos model rockets. It makes the concept clear to everyone. If you spin it and the front doesn't point forward you need a redesign. Then you could show the same with spin testing a reentry module, only in reverse. It's such a basic easy thing that can't lie.
I remember the first Dragon Abort Test. Of course, it being unmanned meant that it didn't necessarily need extra stability. As the Dragon 2 will be manned. It needs a higher degree of safety. So the fins make sense. Great content as always Tim. Blue Origin's New Shepherd Capsule. Isn't the right shape for fins. Grid Fins might be okay though. I'm not a designer. So don't really know how feasible they are.
Wow, that dragon abort test would be one wild ride.
I would say "center of pressure" rather than "center of lift". Excellent video.
SOOO happy i discovered this channel! :D i love these Rocket science vids and simulations with KSP
Excellent explanation, Tim!
Thanks for including ISRO
Now can you mod Kerbal to add differential thrust? An active system to stabilize the capsule during abort, no truck and no fins.
The reason is Dragon was originally intended for the Moon. To return from the Moon, it required a service module. I was modified to service ISS only, the service module was replaced with a trunk that holds solar panels and acts as a spacecraft adapter for the Falcon 9 rocket. But to use Dragon to go to the Moon, it will need some way of returning from Lunar orbit. That means adding propellant tanks and engine(s) to the service module for TEI. Once you add that mass, pad abort engines will not longer be able to drag the service module with it. This will require the capsule to abort without any sort of trunk. So again, demonstrate active differential thrust to maintain orientation just long enough for abort.
Mechjeb adds differential thrust capabilities. It's INCREDIBLY useful for skycranes.
you can use a mod called throttle controlled avionics, it lets you use thrust differential steering and hovering
.
Haven't tried anything like that in KSP for a long time, but many revs ago adding fins to an upper stage was a disaster waiting to happen, and not waiting long, either. By adding fins to an upper stage, you're moving your CoL forward, at least until such time as you jettison the lower stage. Add to that the stability control loop delay plus the noodle joints, and you'd be in for a hysterical (in all senses of the word--funny, terrifying, and organ-displacing) time.
In everyday general aviation, pilots must consider weight and balance calculations before they take off. The center of lift is mostly fixed in a certain position. But the center of gravity (CG) can be shifted depending on where we place the heavier passengers and our baggage and fuel. The greater the distance between the CG and the CL, the more stable the aircraft becomes.
When the CL is behind the CG we call it positive stability. That means that if the airplane is flying straight and level in a normal cruise configuration and you upset the cruise, for example by pulling back on the stick and letting it go, the airplane will oscillate into a waveform and return to normal straight and level flight. That is called "positive stability'. That's a good thing.
However, if the pilot misloads the airplane and places the GC at or near the CL, and upsets the cruise configuration, the aircraft will go into continuous oscillation and its waves will continue as usual. This is called "neutral stability". BTW, some military jets that "fly by wire" are designed for "neutral stability" because of aircraft will maneuver more readily. Safety is conserved by the "fly by wire" computers.
The worst way to misload an airplane to put the CG behind the CL. If you upset the cruise by pulling back on the stick or control wheel, the oscillations will continue to grow in wave height. This is called "negative Stability". No pilot want's to be in a negatively stable condition if he/she enters a stall because it might be impossible to recover from such an upset. Just a little basic aerodynamics 101 for review. So the next time you get into a small airplane, don't be upset if the pilot asks you how much you weight and wants you to sit in any particular seat in the airplane.
Even in a lightly loaded airline jet, the crew may ask passengers to move their seat, for weight and balance purposes.
I have a rocket motor for the top of landers, a toroidal sheath motor designed to leverage the gases as an atmosphere for lift on top of the thrust vector, a thust-lift design the nacelle shaped gives lift and it needs fins to not spin, and to cool flow raising density and thickening the boundary-layer for lift power.
Works in a vacuum, things point to having them on payloads to stabilize on takeoff before it has momentum, and reduce the max pressure reached.
Cheers, tom
❤️ I am blown away 🔥🔥
U r definitely awesome dude
Tun, another really good video. You, along with Amy at Vintage Space, Scott Manley and Curious Droid have become my main source for space news, and increasingly your content has been among the top even in that group. Good stuff!
🙏🙏🙏 wow that’s huge praise! Thank you!!! I greatly admire all those channels and people, so that means a lot. Amy is great. I can’t wait for her new book to be done so she can get back to TH-cam!!!
"... as well as Boeing CST-100 Starliner"
that didn't age well
I really enjoy your channel. Your launch live streams are great. I have totally gotten into rockets because of watching your content. Thanks for all your work!
I had always learned it as 'center of pressure', not center of lift (but center of drag is pretty descriptive).
With the amount of knowledge that you're dropping in your videos, you should start a kickstarter campaign to build your own rocket....
I kind of felt about your astronaut suit the same way Joe wondered about the fins - with the difference that the fins actually serve a purpose...
Since nobody seems to have mentioned this in the first 100 or so comments... notice the clip of an Apollo abort test that starts just before the 3 minute mark. No fins. How do they keep it from turning around? I suppose it's one of two things--possibly those smaller motors at the top of the escape rocket are correcting for the capsule's desire to go flat-end-first... or, possibly, the presence of the escape tower renders the assembly stable. I recall from my model rocket days that a cone's center of pressure (the term we used in those days, side-stepping the question of whether it's more accurately called center of drag or center of lift) is two-thirds of the way back from the point to the base. And that's why the capsule wants to go blunt-end-first: unless it's got some serious ballast in the pointy end, a cone's center of mass is going to be a lot closer to the base of the cone than that. Did the Apollo's big heavy escape-rocket tower, well forward of the conical capsule, move the center of mass far enough forward for the assembly to be stable?
The video is not right. There are important 3 centers on the rocket: center of mass (abbreviated COM or CoM), center of thrust (COT), and the center of lift (COL). If the center of thrust (defined by position of engine nozzles) is above center of gravity and center of lift, then it doesn't matter if center of lift is even above the center of mass. That is why Mercury or Apollo capsules with escape engine tower high above the capsule did not need any fins when escaping away from exploding rocket , even when both had center of lift above the center of mass.
YUP, I GOTTA SEE THAT FALCON 9 GOING BOOM!
Center of mass, center of thrust and center of drag. A dart works as the center of mass is in front of the center of drag. Fins on a rocket keep the center of drag behind the center of mass.
Another great video, looking forward to playing with this in KSP tomorrow morning. Nicely done!
I love that you use KSP as a example. Really gives life to the game
It's crazy that tonight is the first manned spacex flight!
The Crew Dragon fins will push the center of lift quite a way forwards on the Falcon 9 rocket. I hope they have enough gimbal authority to keep the whole vehicle stable. They probably simmed it a lot.
I think the actual term is "Center of Pressure" instead of Center of Lift.
bingo. I'm not a rocket scientist but have built and flown many a model rocket and if you don't get that relationship correct (CG to CP), you have what is known as "an interesting flight"!!! And if your model was built from a kit, when it hits the ground it is said to be "re-kitted". His first demo here was a "re-kit" for sure!!
Aren't lift and pressure the same thing in this case?
@@marctardif9756 no
love your work EA
I'm hoping Everyday Astronaut goes to the DM-1 behind the scenes social media event so we can get more awesome information like this.
There are 3 centers important on the rocket: center of mass (abbreviated COM or CoM), center of thrust (COT), and the center of lift (COL). If the center of thrust (defined by position of engine nozzles) is above center of gravity and center of lift, then it doesn't matter if center of lift is even above the center of mass. That is why Mercury or Apollo capsules with escape engine tower high above the capsule did not need any fins when escaping away from exploding rocket , even when both had center of lift above the center of mass.
Tim you should do more Kerbal Space Program. Go to the planets and their moons and you can also test mods etc.. I’m looking forward for next year!
This channel is underrated
IIRC it is "designed that way" as COB/COG shifts are used to correctly orientate the capsule (and even different shapes were tested).
Looks like a flying little bunker!
Your comparison to the Crew Dragon abort test was really cool, you did a great job!
Good quality, well constructed videos made me a subscriber... Thanks for the good work.
It will be awesome seeing the dragon fly! Loved the video!
Thank you for the awsome info!!!!
Really good explanation!
Indian 🇮🇳 Human Spaceflight mention at 4:11 👏 🚀❤️Gaganyan crew capsule.
Yes there is thrust deferential in ksp, using TCA mod it's amazing
OMG i had no idea they were going to freaking detonate the rocket on the in flight abort. WHAAAAT
I wonder what mission it will be...
NASA wanted real abort test and they will get it
It’s probably to verify that the abort system can both detect a problem _and react to it_ in time to save the crew. It doesn’t do any good for the abort system fire if half the capsule has already been destroyed.
The booster would most likely not survive MaxQ without the dragon on top, so they would lost the booster anyway.
www.faa.gov/about/office_org/headquarters_offices/ast/environmental/nepa_docs/review/launch/media/Draft_EA_for_SpaceX_In-flight_Dragon_Abort_508.pdf the booster is going to shut down its engines, effectively, without telling Dragon about it, so Dragon will think there's something wrong and abort immediately. The report there says the booster is expected to break up, and that they've designed the dummy 2nd stage to facilitate burning of the fuel.
Kerbal is just the best for intuitioning spaceflight. If you don't have it, get it! You will see the world differently after a few hundred hours of kerbal.
That’s looks like a really rough abort ride on the Dragon. Big whip with a quick direction change.
It looks like your first craft on Kerbal with the Mk1 pod and a booster
Amazing video!
Thanks a lot
I didn't actually know they were gonna detonate the Falcon 9 stage. I really can't wait for that now
Haven’t watched the video but they are 100% to look cool af.
Great video! Best in a long time and the first time your KSP demo interested me.
Inflatable fins (think marriage of airbag with 747 escape chute) might make even more sense. Compact, lightweight, instantly deployable, no/minimal control surfaces. They'd give you the desired drag and slipstream without weighing tons during ascent.
I love when you use Kerbal to explain things
CRAP!
how big is the dragon!?!
Great video! Was really cool seeing the real life & kerbal side by side comparison and how close they were.
I recently saw a shooting video using a standard air rifle pellet shape of various sizes used with and without spin to stabilize it and it seems to fly true fired backward as well as forwards, it seems a bullet with a waist and hollow skirt is an ideal shape facing either way.
Thanks for a very informative video! Wondered about the fins myself. Excuse me if the answers are on the surface, but my questions are related to the strange design of the solar panels on Dragon 2: 1) how come they won't be damaged during the ascent? 2) why SpaceX decided to go with unmovable panels in the first place? 3) Are there solar panels on Starliner and if yes, where, if no, how limited its batteries?
Wow you're good at simulating real scenarios, both crs 16 landing and dragon abort test.
Ok You BPS.space and the slo mo guys are my favorite channels
I had no idea that the Soyuz had grid fins on it!! fascinating.
yup, from like the 1980's!!