Michael Duitsman

Michael Duitsman

@DuitsyWasHere

Followers2.6K
Following360

Research Associate @CNS_Updates. Rocket propulsion and radiological security (usually not at the same time). Opinions my own. Faves/RTs ≠ endorsements

Monterey, CA
Joined on August 27, 2015

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We looked inside some of the tweets by @DuitsyWasHere and here's what we found interesting.

Inside 100 Tweets

Time between tweets:
2 months
Average replies
2
Average retweets
9
Average likes
16
Tweets with photos
62 / 100
Tweets with videos
0 / 100
Tweets with links
5 / 100
Since it was popular, I fixed up my Brahmos notes and added extra information on the booster.
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Since it was popular, I fixed up my Brahmos notes and added extra information on the booster.

Meanwhile, in Colorado...
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Meanwhile, in Colorado...

Bureau of Ships made some... interesting graphic design choices here...

If I recall correctly, a lot of the developmental work on naval decontamination was done in the SF bay area.
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Bureau of Ships made some... interesting graphic design choices here... If I recall correctly, a lot of the developmental work on naval decontamination was done in the SF bay area.

14/ UPDATE: I might have made a mistake about the effectiveness of control surfaces at high altitudes. Working through it with @GeorgeWHerbert. Any advice is welcomed. Apologies in advance if I was wrong, I wasn't trying to mislead anyone.

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13/ The Iskander and DF-12 also use thrust vanes. In these missiles, the vanes are used to help control the missile during boost, especially during the first seconds, while the missile accelerates away from the launcher. After main engine cut off, the vanes are useless.
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13/ The Iskander and DF-12 also use thrust vanes. In these missiles, the vanes are used to help control the missile during boost, especially during the first seconds, while the missile accelerates away from the launcher. After main engine cut off, the vanes are useless.

12/ Thrust (jet) vanes are heat-resistant fins protruding into the rocket motor’s exhaust stream. Rotating the vanes changes the direction of the exhaust, steering the thrust. This is a form of thrust vector control. Some missiles (Scud, V-2, etc) rely on jet vanes exclusively.
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12/ Thrust (jet) vanes are heat-resistant fins protruding into the rocket motor’s exhaust stream. Rotating the vanes changes the direction of the exhaust, steering the thrust. This is a form of thrust vector control. Some missiles (Scud, V-2, etc) rely on jet vanes exclusively.

11/ A few more...
The astute amongst you may have noticed these boxes at the base of the missile. These are the housings for the thrust vane actuators.
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11/ A few more... The astute amongst you may have noticed these boxes at the base of the missile. These are the housings for the thrust vane actuators.

10/ Please hold while I write more tweets. In the meantime, here is a video about ATACMS with a narrator that lies and claims that it’s not a ballistic missile.

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9/ (If you think the sheet metal fin on that Iskander looks weird, you’re right; that’s not the real fin. I’ll get to that later.)

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8/ In this picture from yesterday’s North Korean launch, you can see the space between the fin and the missile body, as well as the location of the actuator shaft. The shaft is located in approximately the same position on the fin as in the Russian Iskander (third picture).
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8/ In this picture from yesterday’s North Korean launch, you can see the space between the fin and the missile body, as well as the location of the actuator shaft. The shaft is located in approximately the same position on the fin as in the Russian Iskander (third picture).

7/ The fin connects to the motor via an actuator shaft. The shaft is the only point of contact between the missile and the fin. This is called an all-moving control surface, because the entire fin moves.
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7/ The fin connects to the motor via an actuator shaft. The shaft is the only point of contact between the missile and the fin. This is called an all-moving control surface, because the entire fin moves.

6/ Staying in the atmosphere avoids this problem. Even at 50,000 meters, where the atmosphere is very thin, control surfaces are still rather effective, and only require actuation motors and batteries to operate. In these pictures of ATACMS, you can see the fins and motors.
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6/ Staying in the atmosphere avoids this problem. Even at 50,000 meters, where the atmosphere is very thin, control surfaces are still rather effective, and only require actuation motors and batteries to operate. In these pictures of ATACMS, you can see the fins and motors.

5/ In the vacuum of space, wings and control surfaces don’t work. Spacecraft must expend propellant in reaction control system thrusters in order to maneuver. Propellant has weight, so increasing maneuverability means increasing propellant weight, and reducing payload weight.
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5/ In the vacuum of space, wings and control surfaces don’t work. Spacecraft must expend propellant in reaction control system thrusters in order to maneuver. Propellant has weight, so increasing maneuverability means increasing propellant weight, and reducing payload weight.

4/ How does it enable maneuvering? Staying in the atmosphere means dealing with atmospheric drag. This results in increased airframe heating and deceleration. However, it is also advantageous because it enables the use of aerodynamic control surfaces (steerable fins or wings).

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3/ Depressed trajectories are used for several reasons:
-Shorter flight time
-Enables maneuvering to avoid defenses and increase precision
-Takes longer for enemy radar to spot it
(These figures do not represent the North Korean missile’s trajectory or range)
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3/ Depressed trajectories are used for several reasons: -Shorter flight time -Enables maneuvering to avoid defenses and increase precision -Takes longer for enemy radar to spot it (These figures do not represent the North Korean missile’s trajectory or range)

2/ Missiles like Russia’s Iskander, China’s M20/DF-12, the US ATACMS, and the new North Korean Missile fly on depressed trajectories, never leaving the atmosphere and maneuvering throughout the whole duration of flight. They are sometimes called “quasi-ballistic” missiles.
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2/ Missiles like Russia’s Iskander, China’s M20/DF-12, the US ATACMS, and the new North Korean Missile fly on depressed trajectories, never leaving the atmosphere and maneuvering throughout the whole duration of flight. They are sometimes called “quasi-ballistic” missiles.

Quoted @joshjonsmith

'Missiles like these will start the war': North Korea tests showcase growing capability. Experts weigh in on what Thursday's tests show about the new missiles https://www.reuters.com/article/us-northkorea-missiles-capability-analys/missiles-like-these-will-start-the-war-north-korea-tests-showcase-growing-capability-idUSKCN1SG0CR?feedType=RSS&feedName=newsOne …

1/ Was glad to help with this. Now that it’s out, I can give some explanations. I have the first nine tweets planned out. Then I’ll need to pause and write the rest This thread might end up rather long. I apologize in advance.

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Mulvaney: “These missiles, whatever they were, whatever you want to call them, they were very small and not aimed at Japan, not aimed at Guam, they were aimed up the North Korean coast. So it's a very non-provocative provocation."

Mulvaney: “These missiles, whatever they were, whatever you want to call them, they were very small and not aimed at Japan, not aimed at Guam, they were aimed up the North Korean coast. So it's a very non-provocative provocation."

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Quoted @aldin_ww

#NorthKorea released images of today's missile testing.

#NorthKorea released images of today's missile testing.

I am oddly excited by the use of a tracked TEL. Makes me wonder what else they'll try to put on a tank chassis.

Quoted @ArmsControlWonk

Initial reports put the apogee of the DPRK missiles at 50 km. That is too low for a ballistic trajectory at either stated ranges on a minimum energy trajectory.

Initial reports put the apogee of the DPRK missiles at 50 km.  That is too low for a ballistic trajectory at either stated ranges on a minimum energy trajectory.

If today's launches were of the new SRBM, then the range and apogee are actually in line with the Iskander-M (rather than the export model), though we still can't establish accuracy and maneuverability performance.

Quoted @ArmsControlWonk

Want to see the May 4 North Korea missile launch in 3-D? @grace_c_liu and I took satellite images from our friends at @planetlabs and made a stereogram. You can view it with your phone using a #GoogleCardboard.

Want to see the May 4 North Korea missile launch in 3-D?
@grace_c_liu and I took satellite images from our friends at @planetlabs and made a stereogram.
You can view it with your phone using a #GoogleCardboard.

Can confirm that this works. Can also confirm that Jeffrey spent hours on this yesterday and was super excited by the result.

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