Rocket Motors

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Rocket Motors
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Kerosene and O2

• Must be pumped very fast and at a high pressure.
• Pump turbines spin at 35,000 rpm, which is twice
  as fast as a jet engine.

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Kerosene and O2

• Temperature
• The temp inside the combustion chamber has to be
  extreme in order to achieve maximum thrust.
• Temp raises pressure pressure raises temp.
• As a result, a motor can only be used once.

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O2 (Oxygen)

• As a gas it takes up a great deal of space.
• To compress it, you need to supercool it so it
  becomes a liquid. (-4000 F)
• As a result, you need very strong tanks.

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O2 Continued

• The system must be kept very cold because as it
  will expand as it heats up.
• Must bleed-off this pressure or it will explode.

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O2 Drawbacks

• Tanks are very expensive because they need to be
  very strong but, at the same time, light.
• LOX can only be stored inside the rocket for a
  short period of time.
• LOX is very dangerous because it is so volatile.
• (Supreme Oxidizer)

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Kerosene

• Remains a liquid at room temp.
• Only buns in the presence of oxygen.
• It is relatively heavy and not a very big Bang
  for the Buck

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Russian R-7 (Little Seven)

• Aug. 3, 1957 flew a nuclear strike trajectory.
• Two months later (Oct. 4) launched Sputnik.
• Needed 3-4 hours to fill and prime
• Too Long!!

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Hydrogen/O2

• When a liquid form it is lighter and more
  chemically energetic than kerosene.
• Was used in the Saturn V and the main engines of
  the Space Shuttle.
• Space Shuttle engines are reusable. (not really)

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Hydrogen/O2 Drawbacks

• Hydrogen is very difficult to keep in a liquid
  form.
• Since it is such a small molecule, it will leak
  out of even microscopic holes.
• No flaws in tankgtgtgtgtgtBOOM
• Welding these tanks is very difficult.
• This is why the Russians lost the space race.
  They could not handle H2.

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Hydrogen/O2

• If hydrogen ignites when you dont want it to,
  you have the destructive energy of a small atomic
  bomb.
• Ex. Challenger in 1986

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Hypergolic Chemicals

• Chemicals that will ignite spontaneously on
  contact with each other.
• They are among the nastiest and most toxic
  substances on the planet.

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Hypergolic Fuels

• Can be stored. (Sort of!)
• Very corrosive so they will eat away at anything
  they come in contact with.

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Secret Missile R-16

• October 1960 Single Worst Rocket Disaster
• Used Hypergolic Fuels (Nitric Acid Hydrazine)
  Devils Venom
• On Oct. 23rd the missile was fueled for launch.
• At this time, just like our launches, all
  unessential personnel were supposed leave the
  area.

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Secret Missile R-16

• Nedelin ignored the safety rules and kept around
  150 military and civilian people at the pad.
• Soon after fueling, it was discovered that fuel
  was oozing from dozens of pipe joints and tank
  seams.
• The supposed storable fuel was not storing.

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Secret Missile R-16

• Nedelin characterized the leak as acceptable.
• The following day (Oct. 24) he sent even more
  crew to the pad to fix the problem.
• He himself, demanded a chair to sit in and sat
  within 15-20 meters from the missile.
• The membranes on the fuel and oxidizer lines in
  the second stage had been activated to the
  self-igniting propellants were only one valve
  from the combustion chamber.

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Secret Missile R-16

• An estimated 250 unsuspecting people were still
  around the rocket when the valve was prematurely
  activated.
• Instantly, the roaring flame of the second stage
  engine burst through the fuel tank of the first
  stage directly below it causing an enormous
  explosion of the fully fueled rocket.

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Secret Missile R-16

• Many of the people close by were incinerated
  instantly.
• Next, the upper stage crashed down and spilled
  its fuel into the flames.
• The roadways and tarmac around it melted and also
  caught fire.
• The flames spread for 1000s of meters engulfing
  everyone.

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Secret Missile R-16

• Over 190 people were killed including Nedelin who
  was perched on his chair watching the whole thing.

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Black Powder (China)

• Made from sulfur, charcoal and saltpeter
  (potassium nitrate).
• Clever feature is the chemical mix contains its
  own oxidizer as well as its own fuel.

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Black Powder/Advantages

• External source of oxidizer in not necessary once
  it is lit.
• No super cooling of liquid, no turbo pumps or
  complicated pipes and valves.
• Can be stored for months or even years.
• Worlds simplest rocket motor.
• NASA uses them for to lift heavy satellites and
  the space shuttle.

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Black Powder/Disadvantaages

• All or Nothing Once they are lit, they burn
  until their fuel is used up.
• They can not be throttled and cant be shut down.
• 1986 Challenger A solid booster sprang a small
  exhaust leak. It acted like a small flamethrower
  aimed at the shuttles massive hydrogen tank.

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The Ideal Propulsion System

• Must be simpler than a liquid engine yet more
  controllable than a solid one.

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Hybrid Engines

• Hybrids offer the best aspects of both.
• The fuel grade is made from hydroxy-terminated
  polybutatiene.
• Very cheap and easy to produce.
• Uses Nitrous oxide as an oxidizer which can
  easily stored as a liquid as room temp.
• Has the advantage of being self pressurizing.

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Hybrid

• Nitrous turns from a liquid to a gas jet by
  simply opening a valve.
• No need for any pumps or expensive plumbing.
• Relatively clean burning. Exhaust is mainly water
  vapor, carbon monoxide and nitrogen.

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Hybrid

• Virgin Galactic uses these engines in the Space
  Ship II and their new rocket the Launcher One

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Space Ship II
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Launcher One