# 2018 IREC

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#### jnelson

##### Well-Known Member
The 2018 IREC / Spaceport America Cup is just over a week away. Fortunately, it looks like we won't be roasted like last year.

My team is almost ready. The airframe just needs a couple finishing touches. We'll be doing the 10k SRAD category again.

So, who's going?

#### Eat, sleep, and Fly

##### Well-Known Member
Purdue's team is prepped and ready, we're competing in the 30K COTS division with a minimum diameter CTI N5800 (wish us luck). Now we just have to drive the ~27 hours one way to get there. If you're there definitely stop by and say hi at the range or poster session.

It should be a really great week at an awesome venue!

#### Aksrockets

##### Now with 8% more aluminum
Yeah, i got a 100k shot going on some time this week. Presentation tuesday at 4:00

Casper

#### ChrisAttebery

##### Well-Known Member
That looks wicked Casper. What motor are you using?

#### jnelson

##### Well-Known Member
Just got home... event was significantly better than last year, but they've still got some work to do... I might expand on that later. I took video of almost every flight except for 2 or 3... I'll post that later.

Purdue's team is prepped and ready, we're competing in the 30K COTS division with a minimum diameter CTI N5800 (wish us luck). Now we just have to drive the ~27 hours one way to get there. If you're there definitely stop by and say hi at the range or poster session.

It should be a really great week at an awesome venue!
I saw it, nice job. I heard your team call out a few of the altitude readings on the way up, but what was the max altitude?

Yeah, i got a 100k shot going on some time this week. Presentation tuesday at 4:00
I made sure to be there for the presentation and really enjoyed it, any plans for next year?

#### stealth6

##### insert witty tagline here
While I understand that the new venue is vastly more appropriate, I gotta say I miss this event being in my backyard. Was a favorite of mine to go hang out and spectate at.

View attachment 355973 Yeah, i got a 100k shot going on some time this week. Presentation tuesday at 4:00
Casper

s6

#### jnelson

##### Well-Known Member
While I understand that the new venue is vastly more appropriate, I gotta say I miss this event being in my backyard. Was a favorite of mine to go hang out and spectate at.
Agreed. I'm part of the SUU team. Our first year was the last at Green River. We sure miss the 3 hour drive (now 12).

#### Eyesinthesky

##### Well-Known Member
Uploaded a few videos and images from SAC 2018. This rocket from Oronos Polytechnique went to about 30,100 feet and shot at over 1,000 fps.
https://vimeo.com/276555084
This was the first flight of the event by a team from Turkey. Footage was shot at just under 2,000 fps.

#### stealth6

##### insert witty tagline here
Doug's camera/launch-tower rig is simply awesome.
Another thing I miss about my "backyard" location....I was sometimes helping Doug (and MotoJoe) out a bit on their rig.

s6

#### Rocketjoe13

##### Certified L2
You missed out on another epic IREC. Pitch mounts and rail cameras worked overtime - those Chronos cameras are way kool!

#### Eat, sleep, and Fly

##### Well-Known Member
I saw it, nice job. I heard your team call out a few of the altitude readings on the way up, but what was the max altitude?
We overshot the altitude quite a bit, AFAIK we had the highest at the launch. Hit ~42K at mach 2.5 pulling 31G's. We intentionally overestimated sims assuming it would underperform, sims said ~33 Mach 2.2 and 21G's. Still not sure what happened there, but if we were going to essentially disqualify ourselves that's the way to do it.

My best guess is that there was a pocket of inactive turbulent air surrounding the body. We had a fincan lip which was intended to act as an altitude and speed inhibitor, and I'd be willing to bet we weren't feeling the effect of that. We'll have to wait until we get back to school and can throw it in some CFD to confirm that theory. I'm just glad it held together. A successful minimum diameter N5800, even a heavy one, is no small feat.

#### djs

##### Well-Known Member
I'm just glad it held together. A successful minimum diameter N5800, even a heavy one, is no small feat.
Congrats on this! Better than having to shoot your rocket while it was on the pad, like A+M.

#### RGClark

##### Mathematician
How did your flight go AKSrockets? Flights to 100k are quite an accomplishment.

Bob Clark

#### jnelson

##### Well-Known Member
Okay, here's the compilation video. I got almost every launch.

#### sean_journot

##### Member
Our rocket is at 32:30 in that video (Washington State University). It looks like it has two wind cocking events during launch, either that or we had stability issues; What do you think? I was standing at the cross road 90 degrees out from the video's point of view and it looked like it went straight up from my perspective. was a multiple diameter rocket (6" payload bay, 4" main chute, motor section) which used a fly away rail. Main chute deployed and we had a bearing to (telemetry failure) it but after ten hours of searching we gave up and didn't recover.

#### AlphaHybrids

##### Well-Known Member
Sean - I'd guess that you had stability issues, probably partially due to the two diameters that you had. The larger 6" portion was partially shadowing the fins so they weren't as effective as simulated. That is a disappointment you weren't able to recover the rocket. Does it have identification information in case someone walks upon it in the future?

Edward

#### sean_journot

##### Member
Our team number and school logo were painted on the fins, I doubt anyone will find it out there. They would have to walk within 20 feet of it to spot it.

Using openFOAM in-compressible solvers it appeared that the fins were far enough back that they were not being affected by the payload bay; our max velocity was around 900 ft/s however and there could have been shock waves running around the nose cone but if that caused an instability it should have shown up just before and after motor burn out.

I think that either the rocket was over-stable and passed through a wind sheer or marginally stable at lift off. After studying the concept of stability I don't have faith in the cardboard cutout method anymore and believe that center of pressure is an oversimplified metric for stability. I have an idea of how I can go about developing a 6 degree of freedom simulation that determines stability from a data set derived from CFD simulations; if the rocket is ever found comparing actual flight data with such a simulation may reveal what actually happened.

#### Nytrunner

##### Pop lugs, not drugs
I think that either the rocket was over-stable and passed through a wind sheer or marginally stable at lift off. After studying the concept of stability I don't have faith in the cardboard cutout method anymore and believe that center of pressure is an oversimplified metric for stability. I have an idea of how I can go about developing a 6 degree of freedom simulation that determines stability from a data set derived from CFD simulations; if the rocket is ever found comparing actual flight data with such a simulation may reveal what actually happened.
Great motor choice with the L2200. Sad to hear about the poor flight and recovery.

You must promise me to never let your university team use the cardboard cutout method again. It is an Approximation for helping schoolkids build smaller model rockets. You guys have more technical and mathematical resources at your disposal than the gradeschoolers that the cutout method is meant for.

The center of pressure is a fine concept if it's treated as the resultant point of aerodynamic forces acting on an airframe. That includes pressure distributions, sheer distributions, base drag, etc. What I've been doing recently (strictly for hobby purposes) is using a basic CFD tool to sum and resolve the aerodynamic moments on my airframes and comparing those to the CP provided by programs like OpenRocket.

Also, if your rocket isn't a nice 10:1 Length/Diam build, lean more towards 10-12% of rocket length for distance between CP and CG than relying on 1 "caliber". Heck, which caliber did y'all se? the 6" or the 4!?

#### wyattjohnson35

##### Well-Known Member
Purdue's team is prepped and ready, we're competing in the 30K COTS division with a minimum diameter CTI N5800 (wish us luck). Now we just have to drive the ~27 hours one way to get there. If you're there definitely stop by and say hi at the range or poster session.

It should be a really great week at an awesome venue!
If you're flying an N does that many any flyer with the Purdue team has to be certified with an L3 flight beforehand?

#### Nytrunner

##### Pop lugs, not drugs
Unless they've changed the rules, no

#### wyattjohnson35

##### Well-Known Member
Unless they've changed the rules, no
So essentially you can go and launch N motors to 30k ft without ever having built and launched an L1 much less an L3? Dang.

#### Nytrunner

##### Pop lugs, not drugs
On the surface, yes. That being said, the teams have several data and design deliveries throughout the competition plus safety and readiness checks.

It is a different research environment than what you'll find at the average Tripoli launch and provides a framework for schools and students to engage in these activities without being locked into the Org/certification pipeline. Mentors and certification are great (and I fully support the idea), yet that can be a roadblock for some schools being able to participate. Plus it's a forum for experimentation and innovation outside what normally occurs (with associated risks club activities won't accept), and that experience is priceless. I wouldn't have gotten into High-power rocketry if not for IREC when I was a student.

#### Steve Shannon

##### Well-Known Member
TRF Supporter
If you're flying an N does that many any flyer with the Purdue team has to be certified with an L3 flight beforehand?
Yes, if you wish to test fly it at a Tripoli launch site.

#### boatgeek

##### Well-Known Member
If you're flying an N does that many any flyer with the Purdue team has to be certified with an L3 flight beforehand?
So essentially you can go and launch N motors to 30k ft without ever having built and launched an L1 much less an L3? Dang.
My understanding is that there is a loophole* in the NFPA rules where a university group under the supervision of a professor can fly high power motors without having to go through the normal HPR certification processes. My older kid is on an IREC team, and they have some issues with people having little rocketry experience between LPR and full O hybrids. Many clubs are somewhat skeptical of IREC teams for this reason, and the number of off-nominal flights on the IREC scoreboard bears this out to some extent. For some university teams, I think it's also worth being skeptical about how much supervision the professor is providing, and whether the professor has enough experience to provide adequate supervision.

* One man's loophole is another man's necessary exemption.

#### wyattjohnson35

##### Well-Known Member
My understanding is that there is a loophole* in the NFPA rules where a university group under the supervision of a professor can fly high power motors without having to go through the normal HPR certification processes. My older kid is on an IREC team, and they have some issues with people having little rocketry experience between LPR and full O hybrids. Many clubs are somewhat skeptical of IREC teams for this reason, and the number of off-nominal flights on the IREC scoreboard bears this out to some extent. For some university teams, I think it's also worth being skeptical about how much supervision the professor is providing, and whether the professor has enough experience to provide adequate supervision.

* One man's loophole is another man's necessary exemption.
Does this loophole also apply to high school? At the moment I'm helping my students work up from midpower to L1 to L2 because I think its good to have a strong foundation in good build practices, safety, and of course, actual certification, but just wondering

#### Steve Shannon

##### Well-Known Member
TRF Supporter
Does this loophole also apply to high school? At the moment I'm helping my students work up from midpower to L1 to L2 because I think its good to have a strong foundation in good build practices, safety, and of course, actual certification, but just wondering
It’s only for colleges and universities. Here’s the actual language, but my personal opinion is that it’s self defeating to use the exemption to avoid becoming members of Tripoli or NAR and proceeding through their certification levels. Tripoli membership for students is only $30 for the first year and$20 for renewals. For that you get insurance, access to launch sites with FAA waivers, and access to programs like the Tripoli Mentoring Program, which allows youths aged 12-17 out on the high power range with their mentors.

Here’s the NFPA 1127 exception:
1.3.3 This code shall not apply to the design, construction, production, manufacture, fabrication, maintenance, launch, flight, test, operation, use, or other activity connected with a rocket or rocket motor where carried out or engaged in by the following entities:
(1) National, state, or local government
(2) An individual, a firm, a partnership, a joint venture, a
corporation, or other business entity engaged as a licensed business in the research, development, production, testing, maintenance, or supply of rockets, rocket motors, rocket propellant chemicals, or rocket components or parts
(3) College or university

#### Andrew_ASC

##### UTC SEDS 2017 3rd/ SEDS 2018 1st
Not an IREC team, not going, but to help Wyatt Johnson, my professor got L-1 certified for a SEDS team so we could use sanctioned Tripoli and NAR launch sites. The benefits to Tripoli and NAR are insurance coverage at said sanctioned launch sites after certification. SEDS was lax on req. we appreciated additional oversight offered by LCO/RSO at normal sanctioned events.

I ended up becoming a Tripoli L-1 later.

#### wyattjohnson35

##### Well-Known Member
It’s only for colleges and universities. Here’s the actual language, but my personal opinion is that it’s self defeating to use the exemption to avoid becoming members of Tripoli or NAR and proceeding through their certification levels. Tripoli membership for students is only $30 for the first year and$20 for renewals. For that you get insurance, access to launch sites with FAA waivers, and access to programs like the Tripoli Mentoring Program, which allows youths aged 12-17 out on the high power range with their mentors.

Here’s the NFPA 1127 exception:
1.3.3 This code shall not apply to the design, construction, production, manufacture, fabrication, maintenance, launch, flight, test, operation, use, or other activity connected with a rocket or rocket motor where carried out or engaged in by the following entities:
(1) National, state, or local government
(2) An individual, a firm, a partnership, a joint venture, a
corporation, or other business entity engaged as a licensed business in the research, development, production, testing, maintenance, or supply of rockets, rocket motors, rocket propellant chemicals, or rocket components or parts
(3) College or university
Interesting, so it says that the codes don't apply if you are the company, and Atlas Rocketry is an incorporated company with a 501c3 pending, so all the rules of don't apply to us ? What rules would then apply??

#### Nytrunner

##### Pop lugs, not drugs
Interesting, so it says that the codes don't apply if you are the company, and Atlas Rocketry is an incorporated company with a 501c3 pending, so all the rules of don't apply to us ? What rules would then apply??
That's a really good question

I'd guess it depends on whether your corporation is specifically licensed for research/development/production/testing/maintenance/supply of rockets/rocket motors/rocket propellant chemicals/rocket components or parts.