Sukhoi Su-27/30/33/35/37 Flanker series & Su-34 Fullback - History, Design, Performance & Dissection (Part 1)

[redeyepilot]

I don’t want to enter into this, but I don’t think MiG is saying that the spaceX fins are purposefully designed to be draggy, just that if they are a bit draggy it is not the end of the world. Not totally optimized to be low drag, which would be a design goal for a missile. Since they are used to control the descent if they drag it isn’t a bad thing

[Ziggy1989]

@redeyepilot

I don’t want to enter into this, but I don’t think MiG is saying that the spaceX fins are purposefully designed to be draggy,

Here,

Spoiler

@MiG_23M

Grid fins on the Falcon 9 are optimized as air brakes to slow the rocket down

@MiG_23M

The use of the fin as an airbrake and to slow the rocket down

Can I help you with anything else?

@redeyepilot

just that if they are a bit draggy it is not the end of the world.

For vehicles that renter the earth’s atmosphere near 17,500 mph it is, absolutely.
There is not really any margin for error in the subject putting 220,000–331,000lb payloads into to low earth orbit.

The falcon 9 needs efficient attitude control in the following speed regimes: reentry, high hypersonic, hypersonic, supersonic & transonic. The Grid Fins are aerodynamically designed to work in all 5. However, it is predominately a Hypersonic grid fin.

Making them too draggy when operating in retry can lead to catastrophic consequences.

Too draggy reduces number of flights from increased wear & stress. They can become inoperable in flight due to the immense compression & superheated airflow at reentry speed & hypersonic etc. Or they can simply be ripped off the Falcon 9 and likely take down the vehicle in the process (Space Shuttle Columbia).

[MiG_23M]

You should try comic sans with the bold and enlarged letters

[ZVO_12_INCH]

Spoiler

[BBCRF]

[MiG_23M]

Su-57 is different, of course it can carry quite a few missiles on external pylons as well. What is the maximum payload?

[ZVO_12_INCH]

The most common figure is 10 tons…

[MiG_23M]

I meant the most number of mounted air to air missiles?

[ZVO_12_INCH]

14-16 pieces(P-77-1/ R-74M/R-74M2)…

Spoiler

https://m.vk.com/wall-140312885_307109

[MiG_23M]

So around 12x R-77-1 and 2x R-74M2? Possibly more.

[BBCRF]

The scheme from Arma 3, nothing to do with the IRL

[ID_Heaven]

RD-180 and Merlin are completely different engines.
RD-180 is closed cycle double chamber engine.
Merlin is open cycle single chamber engine.

[Ziggy1989]

They are different engines.

Where was it stated that they are one of the same?

[ID_Heaven]

@Ziggy1989

Where was it stated that they are one of the same?

SpaceX uses RD-180 on Falcon 9

[Joe_Rogan]

Any day now Ziggy

[ZVO_12_INCH]

It does not contradict other data!
http://otvaga2004.mybb.ru/viewtopic.php?id=1998&p=29#p1365056

[Prophet1313]

@Ziggy1989

grid fins are air brakes

Wait is that what you’re arguing??

Jesus christ stop making me agree with Mig_23M. The Grid fins ABSOLUTLY act as airbrakes. Really, anything that generates lift (in this case the force needed to manipulate the booster) necessarily generates drag and it’s a proportional relationship. If it generates a force on the booster through aerodynamic effects it MUST also generate drag.

@Ziggy1989

Yes, Space X uses Russian RD-180 engines on its Falcon 9 rocket.

They absolutely don’t. The Merlin engine used on the Falcon 9 is entirely homegrown. What you’re thinking of is the Atlas 5. That one did use the RD-180 and that’s why it’s now retired, replaced by Vulcan using BE-4s

[Ziggy1989]

lol sorry, about that Prophet. I would never intentionally.

As for the grid fins, they are not airbrakes. they are at best stabilizers with higher drag for immediate stability for in the Soyuz in the event of emergency as explained in detail.

Spoiler

@Ziggy1989

In an abort situation, the booster may be in the process of tumbling or exploding or both when the spacecraft separates. Having draggy fins toward the back of the package quickly straightens out its flight. providing the maximum separation from the booster during the powered portion of the escape and allowing the fairing to separate cleanly from the spacecraft after the escape tower burns out.

Stable flight of a rocket requires that the center of aerodynamic pressure be behind the center of mass. The Soyuz LES abort has to carry both the orbital module (uncrewed during launch) and the reentry module (crewed) with it because the orbital module is stacked above the reentry module. The service module below that is left behind during an LES abort.

@Ziggy1989

Without the fins, most of the pressure would manifest at the point where the base of the LES tower meets the top of the spacecraft fairing, above the orbital module. The center of mass is near the top of the orbital module when the LES is ignited, moving backwards as the LES rocket propellant is expended. With the center of mass behind the center of pressure, the stack would be unstable. Adding the fins moves the center of aerodynamic pressure back, yielding a stable configuration.

I just showed you a diagram of the Soy

Regarding the Falcon 9 its Grid fins are specifically designed for control of pitch, roll & yaw of the Falcon 9. They are hypersonic grid fins.

Spoiler

@Ziggy1989

Falcon 9’s first stage is equipped with hypersonic grid fins which manipulate the direction of the stage’s lift during reentry. The fins are placed in an X-wing configuration and are stowed on ascent and deployed during reentry.

@Ziggy1989

In the atmosphere, RCS thrusters aren’t powerful enough to steer the rocket, and the engine isn’t ignited everytime. The body of the rocket can generate a little bit of lift when moving at the right angle, like a Soyuz. Grid fins are strong enough to resist to the hypersonic flow, that means the air goes by with a speed greater than Mach5 = 6150km/h or, for scientist, 1710m.s^-1. They can control the attitude of the Falcon even at high speeds.)

While the fins are relatively small – they measure just 4 feet by 5 feet (about 1m by 1.5m) – they can roll, pitch, and yaw the 14-story stage up to 20 degrees in order to target a precision landing.

Grids Fins acts like classic control surfaces we can find on an airplane. If they roll 2 by 2 in the same direction (“up - down” and “left- right”) they can control Yaw and Pitch. If you roll the 4 of them in the same direction, the Falcon9 has an excellent roll rate.

[Joe_Rogan]

Aren’t the grid fins just used for manoeuvring?

[MiG_23M]

Seriously, try comic sans