Princeton University attempt at a suborbital space shot?

the model rocket show
madcow rocketry
The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
mikec said:
From their Facebook page:

"We had a successful launch at 0939 MDT yesterday. After a successful boost phase of the first stage, the second stage igniter failed to initiate the upper stage motor. The second stage then reached about 50,000 ft.

We also apologize for the interruption in the live stream Spaceport America due to network issues.

Nevertheless, all other systems performed nominally leading to a perfect recovery of the sustainer 2 miles away. We are very happy with the vehicle’s performance: the full stack reached and survived max-Q at booster burnout, thermal protection surfaces acted as expected, and all onboard electronics performed perfectly. According to our trajectory analysis, we would have likely reached outer space if the second stage had ignited. More data and video will follow.

We look forward to making another attempt in the future, building off lessons learned in both the construction and launch phases of the project!"
Click to expand...

And if the sustainer doesn't light, this is exactly what you'd want to have happen... it comes down on chute to be flown again. I'm sure they learned something out of this, and they probably don't need to do very much to make another go at it. Good job, guys!
 
cerving said:
And if the sustainer doesn't light, this is exactly what you'd want to have happen... it comes down on chute to be flown again. I'm sure they learned something out of this, and they probably don't need to do very much to make another go at it. Good job, guys!
Click to expand...

And not only them. Other university teams and independent amateur teams by emulating their detailed descriptions of the FAA applications and rocket construction details could also make an attempt at suborbital space, especially since it used COTS (commercial off-the-shelf) motors.

Bob Clark
 
cerving said:
And if the sustainer doesn't light, this is exactly what you'd want to have happen... it comes down on chute to be flown again. I'm sure they learned something out of this, and they probably don't need to do very much to make another go at it. Good job, guys!
Click to expand...

It is standard practice to have the recovery electronics bring back the second stage if it doesn't light. No extra design work is needed. The only consideration is that the descent rate will be higher due to the mass of the unfired propellant.

RGClark said:
And not only them. Other university teams and independent amateur teams by emulating their detailed descriptions of the FAA applications and rocket construction details could also make an attempt at suborbital space, especially since it used COTS (commercial off-the-shelf) motors.
Click to expand...

Not exactly. The use of commercial motors limits the options for the flight profile, thrust curve, mass distribution, mass ratio, and second stage ignition characteristics, to name a few. Though, it is certainly faster to get to a flight-ready rocket, but not optimal. This is also contrary to your previous statements that it must be done without an airframe, with a fin can attached to the motor.

I think it was an excellent first attempt for a student team in a short time. The technical document is very good, but needed some additional review that probably wasn't possible in the time frame they had.
 
RGClark said:
Other university teams and independent amateur teams by emulating their detailed descriptions...
Click to expand...
Since they didn't even attempt to recover the first stage and the second stage descent rate was very high, this wouldn't be allowed to fly at any amateur range under HPR rules. Probably Spaceport America is the only place you could try something like this.
 
Spaceport America is the only place you could try something like this......and very few teams can scrape up the launch fee......
 
Nice to see so many people following the flight! It was certainly an ambitious project, but I think overall it went pretty well. Would have loved to see the second stage ignite but still a great flight in my book. Looking forward to making another attempt next year, construction should be easier after all I've learned in making this rocket. Going to be a ton of work again for myself, but at least I will have less classes to deal with doing it as my thesis!

Just glad we got to this point - halfway through the year it didn't even seem like the school was going to let me/us... As our contact at Spaceport America said, Princeton was by an order of magnitude the most overly risk averse/slow school they had ever had to deal with (took 3+ months to get our contract with SA approved by the schools risk management team/office of general counsel despite the engineering dept./faculty approving it from the get go)

jsdemar said:
It is standard practice to have the recovery electronics bring back the second stage if it doesn't light. No extra design work is needed. The only consideration is that the descent rate will be higher due to the mass of the unfired propellant.


Not exactly. The use of commercial motors limits the options for the flight profile, thrust curve, mass distribution, mass ratio, and second stage ignition characteristics, to name a few. Though, it is certainly faster to get to a flight-ready rocket, but not optimal. This is also contrary to your previous statements that it must be done without an airframe, with a fin can attached to the motor.

I think it was an excellent first attempt for a student team in a short time. The technical document is very good, but needed some additional review that probably wasn't possible in the time frame they had.
Click to expand...

Thank you! Yeah I kind of wish I had had more time to put into that report, it kinda got left to the last minute (i.e. two days) between Formula Hybrid competition stuff and shipping out the finalized rocket - definitely left some stuff out unfortunately. Could have easily written double what it was!

Any major design comments? Don't get much feedback/help from the faculty here, only thing they do is fluids/combustion research haha! I would say major things that needed a bit more work were ignition methods and more analysis of the effect of wind on dynamics (some of which was done but not included in the report as my cohort did some of that work so couldn't put it in my personal report). Also left out quite a bit of more broad FEA on things like overall vehicle stack, thermal expansion at joints, vacuum testing of igniters/deployment/batteries, etc.

Our final ignition method used a slow burning igniter and a burst disk on the nozzle to maintain ~ ground level pressure and help the motor come up to pressure faster (recommended by Karl @ AT). Initial analysis of accelerometer looks like both worked as intended, but the disk needed to be sized for more pressure - it ignited and produced momentary thrust then immediately chuffed out.

The instability off the rail seems to be due to an unexpected wind shear/gust off the pad in combo with such a long slender vehicle. We plugged in a 20 mph ground wind into ASTOS and got nearly the exact oscillation shown by the rocket. Combo of slightly larger fins, longer launcher, spinning up booster, and possibly a shroud for sustainer fins are under consideration for solving this for next year.


FredA said:
Spaceport America is the only place you could try something like this......and very few teams can scrape up the launch fee......
Click to expand...

It isn't particularly bad for what you get - ~$5,000 gets you access to WSMR's airspace and things like a place to work with power/AC/fire crews/etc. They're certainly not making money! I would bet most of the 120+ college teams going to the SpacePort Cup pay nearly as much to fly/house/feed their teams - it really is in reach of most teams. On par with cost to go to an FSAE/Formula Hybrid competition as well. Compare it to WSMR which would be $50-100,000 or Wallops which was $100,000's, or BlackRock which is free but smaller and a logistical nightmare especially for an east coast school.
 
"It isn't particularly bad for what you get - ~$5,000 gets you access..."
I thought I read $12k for access....agree that $5k is a pretty good deal.
Especially since you get to save on booster recovery gear! ;-)

Nice try gents - hope you get to go again!
 
FredA said:
"It isn't particularly bad for what you get - ~$5,000 gets you access..."
I thought I read $12k for access....agree that $5k is a pretty good deal.
Especially since you get to save on booster recovery gear! ;-)
Click to expand...

They have a flexible fee, depending on requirements, commercial aspects, and risk. A large, well-known university has a little more clout to negotiate than an individual would have.

Black Rock actually has more recovery area and far easier access than Spaceport America. You are ~3 miles from the restricted property line of the White Sands Missile Range. Getting a waiver there (which I've done a few years ago) is more difficult because the FAA does not control the airspace. And there is minimal road access plus protected areas due to the Native American artifacts survey.
 
RocketHunter said:
...
It isn't particularly bad for what you get - ~$5,000 gets you access to WSMR's airspace and things like a place to work with power/AC/fire crews/etc. They're certainly not making money! I would bet most of the 120+ college teams going to the SpacePort Cup pay nearly as much to fly/house/feed their teams - it really is in reach of most teams. On par with cost to go to an FSAE/Formula Hybrid competition as well. Compare it to WSMR which would be $50-100,000 or Wallops which was $100,000's, or BlackRock which is free but smaller and a logistical nightmare especially for an east coast school.
Click to expand...

Spaceport America is privately run. The others are government run. I wonder if that is related to the fact Spaceport America is a factor of 10 cheaper. This is a primary argument of those supporting commercial space.

Bob Clark
 
RGClark said:
Spaceport America is privately run. The others are government run. I wonder if that is related to the fact Spaceport America is a factor of 10 cheaper. This is a primary argument of those supporting commercial space.
Click to expand...

Wrong again, Bob. Spaceport America is owned and operated by the State of New Mexico. There is no private investment. The $250M (and going) investment is from New Mexico tax payers, like myself. They are still operating at a loss. Virgin Galactic pays a minimum lease fee until (if) they begin operations. There really isn't any regular operating tenants there (CTI and UPA are there occasionally).
 
jsdemar said:
Spaceport America is owned and operated by the State of New Mexico.
Click to expand...
Yikes, you're right, John. Somehow I thought there was at least a shell of a private company behind it, even if it was 100% paid for with state funds, but it's right there in the wikipedia page: "Spaceport America is owned and operated by the State of New Mexico, via a state agency, the New Mexico Spaceport Authority."
 
mikec said:
Yikes, you're right, John. Somehow I thought there was at least a shell of a private company behind it, even if it was 100% paid for with state funds, but it's right there in the wikipedia page: "Spaceport America is owned and operated by the State of New Mexico, via a state agency, the New Mexico Spaceport Authority."
Click to expand...

Odd that in that same wiki entry it is described as:
Airport typePrivate Commercial Spaceport

And when you click on the link for "private" it says:

A privately held company, private company, or close corporation is a business company owned either by non-governmental organizations or by a relatively small number of shareholders or company members which does not offer or trade its company stock (shares) to the general public on the stock market exchanges, but rather the company's stock is offered, owned and traded or exchanged privately. More ambiguous terms for a privately held company are unquoted company and unlisted company.

 Bob Clark
 
plugger said:
Yep. When your exhaust resembles a corkscrew that's a pretty reasonable indicator something is out of whack.
Click to expand...


Saw a discussion on the Arocket list on the Princeton attempt. It noted the corkscrewing in the flight path, i.e., coning, suggesting some possible causes.

From: William Claybaugh <wclaybaugh2@xxxxxxxxx>
To: arocket@xxxxxxxxxxxxx
Date: Sat, 9 Jun 2018 09:07:42 -0600

Launch video can be found at https://www.facebook.com/princetonspaceshot/

The vehicle appears to start coning a few seconds after launch; that would
either be caused by a mechanical misalignment of the vehicle rotational
axis (one or all of nose cone / instrument assembly / upper stage were or
became canted wrt the first stage axis) or due to a rotational mass
asymmerty (typically, failure to spin balance the vehicle).

Still, a good effort,

Bill
Click to expand...

There is no substitute for practical experience. Amateurs well experienced in high power rocketry may be able to do a follow-on to the Princeton rocket, but using their knowledge and experience to avoid making the same mistakes.

Bob Clark
 
RGClark said:
Saw a discussion on the Arocket list on the Princeton attempt. It noted the corkscrewing in the flight path, i.e., coning, suggesting some possible causes.

There is no substitute for practical experience. Amateurs well experienced in high power rocketry may be able to do a follow-on to the Princeton rocket, but using their knowledge and experience to avoid making the same mistakes.
Click to expand...

Already pointed out earlier. These are well-known issues for sounding rockets over the past 75 years. The Princeton team had schedule limitation and most likely knew of the structural/balance/dynamics risks. This is not simply going to go away with follow-up amateur college projects. You need engineered solutions, test iterations, and access to the right resources. It can't just look like a good rocket and simulate ok. There's a big difference between an academic project (the goal is a grade) and a amateur/HPR project (altitude goal, or a personal best, or a cool flight). For a commercial system, add the goals of delivering on-time, under budget, and it must perform well repeatedly. All different Worlds. But, again, the design issues are well known from sounding rocket development over the years, all in the public domain.
 
jsdemar said:
Already pointed out earlier. These are well-known issues for sounding rockets over the past 75 years. The Princeton team had schedule limitation and most likely knew of the structural/balance/dynamics risks. This is not simply going to go away with follow-up amateur college projects. You need engineered solutions, test iterations, and access to the right resources. It can't just look like a good rocket and simulate ok. There's a big difference between an academic project (the goal is a grade) and a amateur/HPR project (altitude goal, or a personal best, or a cool flight). For a commercial system, add the goals of delivering on-time, under budget, and it must perform well repeatedly. All different Worlds. But, again, the design issues are well known from sounding rocket development over the years, all in the public domain.
Click to expand...

Agreed. Moving this conversation forward is there a simple and effective way to "build in" spin stabalization on a booster of a two stage project? I ask as I'm planning to attempt a two stage flight at THUNDA 2019 (75mm to 54mm) and ideally I'd like the stack to be as stable/straight up as possible. I'm going to use a EasyMEGA for staging logic in the sustainer in combination with a CCR HEI CTI forward closure and ideally I'd like to be as close to vertical when the sustainer motor lights, hence the question re spin stabalization. Any advice would be appreciated.
 
plugger said:
Agreed. Moving this conversation forward is there a simple and effective way to "build in" spin stabalization on a booster of a two stage project? I ask as I'm planning to attempt a two stage flight at THUNDA 2019 (75mm to 54mm) and ideally I'd like the stack to be as stable/straight up as possible. I'm going to use a EasyMEGA for staging logic in the sustainer in combination with a CCR HEI CTI forward closure and ideally I'd like to be as close to vertical when the sustainer motor lights, hence the question re spin stabalization. Any advice would be appreciated.
Click to expand...

To have effective spin stabilization the rocket must be balanced, like a car tire has to be. Otherwise, spinning will cause a precession or corkscrewing motion. Likewise, if the stack flexes it will wobble and possibly fail dramatically.
In pro rockets they have a spin table to test the payload section. The advanced design of the motor is assumed to be balanced (no offset cores).
If the mass balance is taken care of, the aerodynamic symmetry needs to be considered. Camera pods, fin alignment (4 is better than 3), and other external feature.
Imparting a spin may be done using slight fin canting or using fin tabs. Also, some small sounding rockets in the past have used rifled launch towers.
The design process to predict all this requires lots of math and high-end simulations. Or many iterations with piles of dead rockets.
 
Here are some videos of our boost. It's straighter than you think - the oscillations that were noted were greatly exaggerated due to the camera angle in the previous video.

https://drive.google.com/open?id=1tZrbbeyEAmpa48otXwp8ZAANWY3WrsxG
https://drive.google.com/open?id=1tTp-SXR3hsv0SFmVRXbDHIRB3dXBDJ_1

The angular motions shortly after rail exit were not coning, as the vehicle did not roll up until after the dramatic oscillation.

What earlier posters discussed (geometric axis different from center of mass axis) is a bigger concern when the roll rate passes through the undamped pitch natural frequency, known as the period of roll-resonance. This can lead to roll lock-in, characterized by loss of directional, lateral, and longitudinal stability. This did not happen either, becaause our roll rate never touched the pitch natural frequency.

That said while we didn't have the resources to do spin-balancing, like Wallops, our vehicle was fairly symmetric in its mass distribution.
 
saadzmirza said:
Here are some videos of our boost. It's straighter than you think - the oscillations that were noted were greatly exaggerated due to the camera angle in the previous video.

https://drive.google.com/open?id=1tZrbbeyEAmpa48otXwp8ZAANWY3WrsxG
https://drive.google.com/open?id=1tTp-SXR3hsv0SFmVRXbDHIRB3dXBDJ_1

The angular motions shortly after rail exit were not coning, as the vehicle did not roll up until after the dramatic oscillation.

What earlier posters discussed (geometric axis different from center of mass axis) is a bigger concern when the roll rate passes through the undamped pitch natural frequency, known as the period of roll-resonance. This can lead to roll lock-in, characterized by loss of directional, lateral, and longitudinal stability. This did not happen either, becaause our roll rate never touched the pitch natural frequency.

That said while we didn't have the resources to do spin-balancing, like Wallops, our vehicle was fairly symmetric in its mass distribution.
Click to expand...

Is there a set length for the launch rail? I noticed the rocket straightened up after awhile. Could it have been that a longer rail would have allowed spin-stabilitization to be in effect by the time it left the rail?

Bob Clark
 
saadzmirza said:
Here are some videos of our boost.
Click to expand...
Not to sound critical, but you'd think that with all this money and effort spent, you might have had somebody with an actual video camera and a zoom lens, not just a couple of phone videos. It would have been well worth it for diagnosis.

Is the flight data going to be posted?
 
RGClark said:
Is there a set length for the launch rail? I noticed the rocket straightened up after awhile. Could it have been that a longer rail would have allowed spin-stabilitization to be in effect by the time it left the rail?

Bob Clark
Click to expand...

No.

A rocket can't begin to spin while engaged to a straight rail.

Some sounding rockets (Loki Dart, for example) use(d) a helical launch tower to induce spin at launch. Building one is in itself a huge endeavor and many tests (expensive, defense department budget kind of money) were done before the final design was perfected.
 
plugger said:
Agreed. Moving this conversation forward is there a simple and effective way to "build in" spin stabalization on a booster of a two stage project? I ask as I'm planning to attempt a two stage flight at THUNDA 2019 (75mm to 54mm) and ideally I'd like the stack to be as stable/straight up as possible. I'm going to use a EasyMEGA for staging logic in the sustainer in combination with a CCR HEI CTI forward closure and ideally I'd like to be as close to vertical when the sustainer motor lights, hence the question re spin stabalization. Any advice would be appreciated.
Click to expand...

I recommend not using spin stabilization in combination with an EasyMega. I know for sure that rotation will affect the ability of the gyros to determine the tilt angle, although I can't claim at this moment (until I run some tests) what the effect is of continuous rotation in one direction. For now, I would just not do it.

Jim
 
saadzmirza said:
Here are some videos of our boost. It's straighter than you think - the oscillations that were noted were greatly exaggerated due to the camera angle in the previous video.

The angular motions shortly after rail exit were not coning, as the vehicle did not roll up until after the dramatic oscillation.

What earlier posters discussed (geometric axis different from center of mass axis) is a bigger concern when the roll rate passes through the undamped pitch natural frequency, known as the period of roll-resonance. This can lead to roll lock-in, characterized by loss of directional, lateral, and longitudinal stability. This did not happen either, becaause our roll rate never touched the pitch natural frequency.

That said while we didn't have the resources to do spin-balancing, like Wallops, our vehicle was fairly symmetric in its mass distribution.
Click to expand...

Are you saying you had an intentional method to spin up the rocket after it left the rail?

You must have some sort of onboard data to show accel (and maybe gyro) information. You can't use video to verify motion artifacts like pitch and roll oscillations. You have one initial significant pitch deviation followed attempts to recover. The source of that pitch event could be many things, including: structural flex, wind shear, shifting payload, dynamic resonance, nozzle failure, etc.
 
mikec said:
Not to sound critical, but you'd think that with all this money and effort spent, you might have had somebody with an actual video camera and a zoom lens, not just a couple of phone videos. It would have been well worth it for diagnosis.
Click to expand...

Do you mean like these?

[video=vimeo;274888874]https://vimeo.com/274888874[/video]
[video=vimeo;272356856]https://vimeo.com/272356856[/video]
[video=vimeo;272357032]https://vimeo.com/272357032[/video]
 
Eyesinthesky said:
Do you mean like these?
Click to expand...
Those are really cool, and far more diagnostic than the cell phone videos for the early ascent, but I don't think being almost directly below the rocket is the optimal viewpoint.
 
Eyesinthesky said:
Do you mean like these?

[video=vimeo;274888874]https://vimeo.com/274888874[/video]
[video=vimeo;272356856]https://vimeo.com/272356856[/video]
[video=vimeo;272357032]https://vimeo.com/272357032[/video]
Click to expand...

Funny these videos don’t show up On the desktop version.
 
JimJarvis50 said:
I recommend not using spin stabilization in combination with an EasyMega. I know for sure that rotation will affect the ability of the gyros to determine the tilt angle, although I can't claim at this moment (until I run some tests) what the effect is of continuous rotation in one direction. For now, I would just not do it.

Jim
Click to expand...

Well there goes that plan! Thanks for sharing Jim.
 

Similar threads

RGClark
Attempt towards an amateur orbital rocket.
5 6 7
Replies
183
Views
12K
bad_idea
bad_idea
RGClark
  • Locked
USC's rocket for suborbital attempt ground tested.
2
Replies
37
Views
5K
Peartree
Peartree
RGClark
Unexpectedly high RASAero estimate for a two-stage rocket.
3 4 5
Replies
142
Views
16K
jsdemar
jsdemar
Winston
Joint Strike Missile destroys target in challenging flight scenario
Replies
0
Views
1K
Winston
Winston
verex
TRSOV-1A experimental two-stage rocket
Replies
3
Views
840
RocketFeller
RocketFeller

Latest posts

Back
Top