# Tag Info

10

In the USA you must be at least 18 years old for the following, so that video may be incorrect. For example HPR Level 1 Certification by the National Association of Rocketry or NAR provides certification for: Level 1 allows the purchase and use of H and I impulse class motors; solid and hybrid. Certain F and G motors may also require Level 1 certification ...

8

First things first: Many launch vehicles initially operate open loop, with guidance and control based solely on time since ignition until main engine cutoff. Precise guidance, navigation, and control becomes much easier when the launch vehicle has left the bulk of the atmosphere behind. A wide variety of sensors exist for those vehicles that instead use ...

7

Ground control of the rocket should know the speed. A proven method used since the V-2 of WWII uses the doppler frequency shift of radio signals. A signal with known and very stable constant frequency is send from ground to the rocket. The rocket sends a signal back derived from the received signal, for instance the doubled frequency ( or another constant ...

6

Isentropic Flow First off: the flow in a real rocket nozzle is not isentropic. It is a simplifying assumption that comes reasonably close to real world observations. As is all of ideal rocket theory, which you are most likely studying. So you are absolutely right, there are losses due to heat flowing to the surroundings and friction losses at the nozzle wall....

4

It sure is, by some small portion of the industry. I don't think we'll be seeing any big EthyLox (if you'll excuse the neologism) boosters taking off as first stages, though: it's a complicated thing to deal with, Ethylene. it being a room temperature gas means it entails all the hassle methane or hydrogen brings (i.e. you need to chill it down in order to ...

4

I agree with your analysis. To maintain a nominal engine inlet mixture ratio, the main chamber must operate above the nominal mixture ratio to compensate for the lower mixture ratio in the gas generator. This sentence makes a certain amount of sense in isolation; if the complete engine specifies a given mixture ratio, then the main chamber will be at a ...

3

First of all: great observation! This is indeed the reason why pressure fed rocket engines are limited in possible chamber pressure, the added weight from the tanks isn't worth it at a certain point. Which is why we have pump fed rocket engines. Question 1: Some equations from Ideal Rocket Theory: Specific Impulse is the characteristic velocity divided by ...

2

This has essentially been cleared up, but unfortunately nobody posted an answer. Since that's an unfortunate situation on SE, here's a quick summary. There's indeed a need for such a manoeuvre, the term used is "Powered Explicit Guidance". A very simple launch model is: Do a gravity turn. When the trajectory arc reaches the target orbital altitude,...

2

Although I agree with Organic Marble that open expander cycles should most likely split the fuel before the cooling jacket, there are some examples where this isn't the case. For example in the RD0146 there is a split of the fuel line after the cooling jacket (see image), although this is just to power the fuel boost pump (so in essence it is more a closed ...

2

The equation shows that the cross-sectional area of the nozzle depends on the local pressure $P$ and values that are constant. So, he expects you to differentiate with respect to $P$, set the result to zero and solve for the value of $P$. Sounds like a fun project. I would let $x=P/P_c$ and take derivative wrt x. Some books go through equations with Mach ...

2

"You save a bit less than 2 minutes of rocket" or "half a stage less" or "You can cut the boosters" One simple way to go about this is just to see how much of a rocket is spent reaching the initial conditions you are providing for free. The Saturn V S-IC stage cuts off after 2.5 minutest at 67km and 2,300m/s Space Shuttle SRB ...

1

Maybe the key lies in equating the difference in gravitational potential energy between that point and at the surface while accounting for the change in mass due to combustion and loss of fuel, and the product of the mass of the fuel and its calorific value.

1

It seems like the principles are similar, holding clamp at the bottom for lift-off and one on the top to set it upright. Compare for example this set-up of the Electron at Launch Complex 1 pad A with the set-up of the Falcon 9 at KSC pad 39A. It also matters which launch pad you compare with ofcourse, Falcon 9 mostly launches from SLC-40, but also from 39A ...

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