egp
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- May 9, 2017
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Wouldn't be fun if RGClark, Andrew_ASC, and nickcodybarrett were all at the same university?
Have you ever seen them in the same room? Maybe they are all the same person?
Wouldn't be fun if RGClark, Andrew_ASC, and nickcodybarrett were all at the same university?
Maybe you could show us how to slide rule.Have you ever seen them in the same room? Maybe they are all the same person?
... No one here will be surprised if Princeton, USC, or other amateurs cross the Karman line, and no one is suddenly going to acquire a many-thousand dollar filament winder and a 60 quart mixer as a result. It has been done before (CSXT) and all that was shown is that the investment required was significant.
Did you even read my previous post?People say they won't be surprised by it. But if that were the case, there wouldn't be so much strenuous argument against it.
Crossing the Karman line by university teams or independent amateurs is important, because the natural progression after that is to do a fully orbital flight. But then the suborbital rocket can form the the first, and largest, and most expensive, stage(s) of the orbital rocket.
Once the mindset is broken against it for the suborbital case, it will be recognized there really is no impediment to the fully orbital case either.
Bob Clark
This is exactly the problem with your posts, the false equivalency you apply to things. People won't be surprised when universities succeed at suborbital flight, but not because it is easy as you suggest but because they have large budgets and access to facilities and laboratories that often rival major corporations. To say "if a university can do it, so can an amateur" is a false equivalency. A university succeeding at it therefore doesn't open any does to others to replicate they're results.People say they won't be surprised by it. But if that were the case, there wouldn't be so much strenuous argument against it.
Crossing the Karman line by university teams or independent amateurs is important, because the natural progression after that is to do a fully orbital flight. But then the suborbital rocket can form the the first, and largest, and most expensive, stage(s) of the orbital rocket.
Once the mindset is broken against it for the suborbital case, it will be recognized there really is no impediment to the fully orbital case either.
Bob Clark
Did you even read my previous post?
You're referring to the objection that I did not consider the mass of the payload that could be lofted to suborbital space for it to be used as a first stage of an orbital launcher.
We can make a comparison to the SpaceLoft XL by UP Aerospace suborbital sounder rocket. It uses a Cesaroni made rocket motor with carbon fiber casing:
https://www.cesaroni.net/news.php
It's listed as carrying a 412 lbs propellant load. and 0.8 propellant fraction, so the total mass of the motor only would be 515 lbs, 234 kg. Now according to the UP Aerospace SpaceLoft XL payload guide, the total mass of their rocket with payload can be 354 kg:
SpaceLoft® XL Sub-Orbital Launch Vehicle.
The SpaceLoft® XL has an overall height of 6.1 meters, a
maximum diameter of 26.4 centimeters, and a maximum
lift-off weight (including payloads) of 354 kg in its
standard mission configuration.
https://www.upaerospace.com/custom-1/UPA PUG Lite R121214.pdf
So for the use as a first stage of an orbital launcher, the Cesaroni motor could loft, 354-234 = 120 kg to suborbital space. Take the required tangential delta-v for orbit as 7,400 m/s, once you subtract off the velocity you get for free from the Earth's rotation. For 3 additional stages, assume they also have a 0.8 propellant fraction, such as also using carbon fiber casing. Then I estimate you can get a payload of 2 kg to orbit, by the rocket equation.
The USC student rocket scheduled to launch in a week is to be a suborbital rocket about half-size to the Spaceloft rocket, and will also use carbon fiber casing. Then estimate the payload to orbit with three additional stages as ca. 1 kg.
Bob Clark
Not nearly that clever or entertaining.Does this thread remind anyone else of Monty Python's Argument Clinic?
Not nearly that clever or entertaining.
OP added to ignore list and I'm not looking at this thread any more.
Best post of the thread......
Let it be known by all that Bob Clark is not related to me.
Mark Clark
I only wish the ignore list was able to hide threads started by a given user, not just their posts. That would be a treat.
Back to "Karman line" AGAIN...
You've all been "BobClarked"! See my post here.
Technically, flying an Estes Alpha on an A motor is suborbital...
Technically, flying an Estes Alpha on an A motor is suborbital...
This....Redo your sim with realistic data and see what your result is...
It is possible to reach space using a N to N staged rocket *if* you don't have the requirements that we as hobbyist have. We have a requirement to keep frangible metals to an absolute minimum. We have a requirement to fully recover all parts/stages. We have a requirement to meet FAA regulations. Nearly all of us have budget restrictions. Basically, if we could ignore all the requirements we have, it would be just as easy as these universities are finding it is. Not a walk in the park, but not limited to governments any more either.
As for your simulations, please keep in mind that simulations are not real world and you can't say something is 100% possible because it worked in the sim. Sims take shortcuts, sims have errors, sims make assumptions, sims are only as good as the data you feed them. Redo your sim with realistic data and see what your result is. Now add all the requirements that we have into that sim and see what happens. We as a hobby have come very far in the last decades but except for a few of us, we're still not quite there yet.
Did you actually read the first page of the PDF?
There is a chart of payload mass to altitude, right at the bottom of page 1. To the 115km nominal altitude you only have 40kg of payload space. That's only 700 g of payload by your math, and you haven't considered any control hardware. You will need attitude control (e.g. cold gas thrusters), because if you're not perfectly horizontal you'll burn up. And you'll need ignition control for all of your various stages, and you'll need to make it semi-rad-hardened and capable of working at extreme temperatures at either end of the scale. That's not going to be cheap or light. All without having it collapse under 14 G loads.
Show me a full-attitude-control rad/temp hard system under 24oz and I'll move on to the next issue. There's a reason spaceflight is expensive.
The SpaceLoft XL suborbital sounding rocket by UP Aerospace, Inc. is launched from Spaceport America in New Mexico. As with most rockets sent to suborbital or orbital space, the SpaceLoft XL rocket does not recover the rocket booster, though it does recover the payload section. Readers of this forum are familiar with the Spaceport America site as it is also where university competitions of rocket launches are often held.
I believe the Princeton team aiming for a suborbital space launch near the end of this month will also launch from Spaceport America. The Princeton team is very open to discussing the process towards getting to this point and also the technical details of their rocket. Amateurs interested in attempting a suborbital space launch and interested in the question of the necessity of recovering their boosters should be able to get useful information from them.
About the sims, I am just getting started using them. I would be interested to see what the results are for others who did sims for O8000-to-N1000, N5800-to-N1000, and N5800-to-N5800 rockets. For one thing I don't know what are the best designs for fins for rockets expected to reach supersonic speeds. Actually for reaching the Karman line, the needed speeds are hypersonic.
Bob Clark
You're referring to the objection that I did not consider the mass of the payload that could be lofted to suborbital space for it to be used as a first stage of an orbital launcher.
We can make a comparison to the SpaceLoft XL suborbital sounder rocket by UP Aerospace. It uses a Cesaroni made rocket motor with carbon fiber casing:
https://www.cesaroni.net/news.php
It's listed as carrying a 412 lbs propellant load. and 0.8 propellant fraction, so the total mass of the motor only would be 515 lbs, 234 kg. Now according to the UP Aerospace SpaceLoft XL payload guide, the total mass of their rocket with payload can be 354 kg:
SpaceLoft® XL Sub-Orbital Launch Vehicle.
The SpaceLoft® XL has an overall height of 6.1 meters, a
maximum diameter of 26.4 centimeters, and a maximum
lift-off weight (including payloads) of 354 kg in its
standard mission configuration.
https://www.upaerospace.com/custom-1/UPA PUG Lite R121214.pdf
So for the use as a first stage of an orbital launcher, the Cesaroni motor could loft, 354-234 = 120 kg to suborbital space. Take the required tangential delta-v for orbit as 7,400 m/s, once you subtract off the velocity you get for free from the Earth's rotation. For 3 additional stages, assume they also have a 0.8 propellant fraction, such as also using carbon fiber casing. Then I estimate you can get a payload of 2 kg to orbit, by the rocket equation.
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