# Princeton University attempt at a suborbital space shot?

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#### RGClark

##### Mathematician
This seems to be saying that Princeton's Rocketry Club will be making an attempt at a flight beyond the 100 km von Karman line in May, 2018:

If so, then we may have a space race between Princeton and USC, which earlier announced they'll make a suborbital space flight attempt April, 2018:

The Princeton rocket appears to be based on the famous Super Loki boosted dart suborbital launcher:

Space Data PWN-12 Super Loki ROBIN.
http://www.designation-systems.net/dusrm/n-12.html

That page doesn't give the weight of the Super Loki ROBIN, but it's probably somewhat less then this version which weighed 31 kg:

Space Data PWN-10 Super Loki Datasonde.
http://www.designation-systems.net/dusrm/n-10.html

The ROBIN version used a lighter and thinner "dart" than the Datasonde version that allowed it to reach beyond 100 km altitude. The Datasonde version was limited to 70 km altitude.

A little more about the Princeton project here:

Iain in Princeton Rocketry April 20, 2018
Princeton Rocketry Club Aiming for May Spaceshot.
https://mach5lowdown.com/2018/04/20/princeton-rocketry-club-aiming-for-may-spaceshot/

It discusses the Princeton rocket will use commercial motors. Using commercial motors gives you another level of safety.
Also, it seems to saying here it's somewhat different than the Super Loki because it does have motors in the second stage.

If Princeton succeeds, then given the rockets small size of less than 31 kg, it's probably a launch other universities with high power rocketry programs could emulate.

Bob Clark

#### Andrew_ASC

##### UTC SEDS 2017 3rd/ SEDS 2018 1st
Well they have papers on the Coyote missile, that Virginia Tech... Lol.

#### egp

##### Well-Known Member
Well they have papers on the Coyote missile, that Virginia Tech... Lol.
I dont understand.

#### egp

##### Well-Known Member
Thats a bit harsh, but fund raising has been part of the teams focus.

I was trying to make the point that Collegiate rocketry is very much alive, which is a good thing for the profession and the hobby of model rocketry. Student teams are doing things that were once unimaginable. That is very cool.

At VT, we have a number of teams. One is participating in IREC, and OLVT doing their own thing with goal of orbital payload. One club is certifying (L1) something like 20 students this semester (big order from Wildman!). OLVT has been able to secure industry sponsorship from major companies with HQ in Virginia, so I guess their website has been successful.

#### Andrew_ASC

##### UTC SEDS 2017 3rd/ SEDS 2018 1st
I don&#8217;t understand.
It was graduate level work on the solid fuel ramjet that Aerojet calls proprietary. The political correct name is "Numerical modeling of a ducted rocket combustor with experimental validation"

They dork missile motors for Aerojet.

#### Andrew_ASC

##### UTC SEDS 2017 3rd/ SEDS 2018 1st
I don&#8217;t understand.
Most people don't understand. It's a solid fuel ramjet. There's blank pages on those since 1974.

#### mpitfield

##### Moderator
Staff member
Global Mod
I see Coleman let the cat out of the bag.

#### egp

##### Well-Known Member
Most people don't understand. It's a solid fuel ramjet. There's blank pages on those since 1974.
Andrew, you don't know me. Please don't be so condescending. I presume that you are referring to the GQM-163 Coyote, but a sea-skimming supersonic rocket has nothing to do with our student orbital launch vehicle team (OLVT), or the team at Princeton. I weighed in on this thread because I think it is exciting that many groups of university students across the country are aiming for very ambitious projects. For the well-funded teams, they are doing some amazing things that were unimaginable not so long ago.

#### dhbarr

##### Amateur Professional
Now if back in my college competition days you just had a composite casing for the second stage and an army of free postgrad labor to work the top secret CFD, you could go to orbit like The Man doesn't want!

Don't take it too serious, or me either for that matter.

#### RocketHunter

##### Well-Known Member
I see Coleman let the cat out of the bag.
A little bit at least! A bit more recent info on FB page: https://www.facebook.com/princetonspaceshot/posts/827101934147282.

Launch contract with spaceport america and our FAA waiver are both nearly finalized, and the vehicle is just about done and ready for ground testing. Only four weeks to go! Going to be happy when I'm truly done building this thing, as one tries to make things lighter and stronger the time to make them goes up exponentially and the margin for error vanishes!

#### egp

##### Well-Known Member
A little bit at least! A bit more recent info on FB page: https://www.facebook.com/princetonspaceshot/posts/827101934147282.

Launch contract with spaceport america and our FAA waiver are both nearly finalized, and the vehicle is just about done and ready for ground testing. Only four weeks to go! Going to be happy when I'm truly done building this thing, as one tries to make things lighter and stronger the time to make them goes up exponentially and the margin for error vanishes!
Good luck! We look forward to hearing about your attempt and hope that it is successful.

#### jsdemar

##### Well-Known Member
A little bit at least! A bit more recent info on FB page: https://www.facebook.com/princetonspaceshot/posts/827101934147282.

Launch contract with spaceport america and our FAA waiver are both nearly finalized, and the vehicle is just about done and ready for ground testing. Only four weeks to go! Going to be happy when I'm truly done building this thing, as one tries to make things lighter and stronger the time to make them goes up exponentially and the margin for error vanishes!
When is the target launch date for your Space shot?

#### RGClark

##### Mathematician
I tried to model a two stage rocket using commercial motors with an O-class booster and N-class sustainer in RASAero II. But I was getting unreasonably high values for the altitude well above the Karman line of 100 km. A simulation I did in OpenRocket gave a more conventional answer of 8 km. But I'm just starting using these programs. Perhaps someone more familiar with them can do runs to check this.

Here's an image of the rocket in RASAero II:

It uses the CTI O8000-P for the booster and an Aerotech N1000W for the sustainer.

Bob Clark

#### RGClark

##### Mathematician
USCRPL announced on their mailing list that they have scheduled May 5th for their suborbital launch.

http://www.uscrpl.com/join-us

Bob Clark

#### RGClark

##### Mathematician
I attached the OpenRocket sim to this post. I wanted to attach the RasAero sim but the extension on the RasAero files are not among those allowed by the forum to be uploaded.

Anyone know how to upload a RasAero sim?

Bob Clark

View attachment O8000 to N1000.ork

#### jsdemar

##### Well-Known Member
I attached the OpenRocket sim to this post. I wanted to attach the RasAero sim but the extension on the RasAero files are not among those allowed by the forum to be uploaded.

Anyone know how to upload a RasAero sim?

Bob Clark
Save it somewhere else (Dropbox, etc.) and post a link to it.

You may get more replies to your simulation learning curve if you start a new thread with an appropriate topic.

#### Chuck Rogers

##### Well-Known Member
Bob:

For rockets of this type, I recommend using the settings All Turbulent Flow (Pages 37-19 in the RASAero II Users Manual), and Rough Camouflage Paint (Pages 34-35 in the Users Manual). Mach 3+ rockets typically have roughened surfaces from the scarring from aerodynamic heating, which trips the flow to turbulent flow, and increases the surface roughness. From altitude comparisons (predicted altitude compared to actual altitude from flight data) for Mach 3 class rockets, these settings provide the most accurate altitude predictions.

Does the rocket have a rail guide or launch shoe? An appropriately sized one has to be added.

You can see the trend here. As you add more and more realism, the altitude keeps falling.

These types of rockets are very sensitive to weight and Drag Coefficient (CD). You'll see a considerable decrease in altitude from using All Turbulent Flow and Rough Camouflage Paint, compared to the default (All Turbulent Flow Box Not Checked) Laminar-Transition to Turbulent-Turbulent Flow and the Smooth (Zero Roughness) settings. Again, for Mach 3 class rockets these settings have provided accurate RASAero II altitude predictions up to 120,000 ft.

Your second stage empty weight is really inaccurate. An N1000W has a loaded weight of 27.3 lbs. Your second stage loaded weight is only 30 lbs. It's unrealistic that the rest of the second stage, minus the motor loaded weight, is only 3 lbs. I'm guessing your first stage empty weight is also inaccurate. These unrealistically low empty weights will have a BIG effect on the apogee altitude.

Take a look at the empty weight of the Loki Dart first stage, to get some idea of the empty weight of what the first stage or second stage would look like. Of course that would include the Loki Dart motor case, but that will represent the metal airframe over the motor you would like use. If you mount Fin Cans to the motors, then the weight would be conservative. Which reminds me, you'll likely use Fin Cans on each stage. They will cause additional drag, so you will have to add Fin Cans to your configuration.

Could an amateur build a rocket with as low of an empty weight as a Loki Dart first stage?

Add the above to the RASAero II sim, and put in more realistic empty weights, and you'll improve the realism of your altitude prediction.

Chuck Rogers
Rogers Aeroscience

#### RGClark

##### Mathematician
USC's rocket propulsion lab just announced on their mailing list that they are pushing back their suborbital space flight attempt from May 5th to May 19th so as not to conflict with Finals week.

To subscribe to their mailing list:
http://www.uscrpl.com/join-us

Bob Clark

#### Andrew_ASC

##### UTC SEDS 2017 3rd/ SEDS 2018 1st
They can always reach out to UTSI if they need a Mach 4 wind tunnel. Or NAS Tullahoma for more Mach. I'm not familiar with VT wind tunnel facilities. I'm just a graduating senior mech engineer student with some competition rocket experience (which seems toy like compared to this), but if I was on that VT project I'd want real drag coefficients not just CFD math models, because of the expenses and uncertainties involved. They can experimentally flutter those fins in a wind tunnel before it leaves earth as added plus, for the expense of wind tunnel testing which may save VT money on liabilities later. Actual thermal data may be nice too. Serious projects demand respect and even engineering students and professors have limitations on tooling and test equipment which will limit theoretical testing abilities in the design phase. CFDs don't appreciate large angle of attack changes at high mach.

Depending on what kind of deviations off flight path you are expecting, it may take a VT defense contractor employed engineering student running a model in Missile Datcom at a defense contractor (with permission), or an actual wind tunnel test at angles of attack due to limitations of math models. And even the Air Force ripped fins off a sounding rocket once going Mach 4. Some CFDs do up to Mach 25, but questionable accuracy is at high angles of attack. What you are attempting isn't always trivial or well known empirically. Real world wind tunnel data is expensive.

#### jsdemar

##### Well-Known Member
News is that the second stage did not light.

I believe it was a red Loki M1378?

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#### JimJarvis50

##### Well-Known Member
News is that the second stage did not light.
Didn't use one of your igniters??

Jim

#### jsdemar

##### Well-Known Member
Didn't use one of your igniters??
It will be interesting to learn what they used as a second-stage ignition system, and why it failed. Sustainer came back under 'chute, from what I can tell.

#### timbucktoo

##### Well-Known Member
Staff member
Global Mod
News is that the second stage did not light.

I believe it was a red Loki M1378?
I always thought that red motors were a bad choice for 2nd stage, hardest to light.

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