Bare Necessities: N5800 C-Star Flying Case

Just an update-We have mostly settled on a new front-end design. The vehicle mass without motor case is currently at around 7.01lbs; I'm anticipating hitting our 8lb target on the head with recovery hardware etc.. Our new design will be substantially easier to prep on the field as well, and we are discarding our old female mold in favor of vacuum-bagged layer-by-layer layup on a CNC's male mold plug, which will enable us to CNC turn the final profile in ablative, as well as to thoroughly check and test for voids in every layer of the layup, post-curing the entire assembly into a monolithic piece.






The remaining question is flight avionics. Based on its success in the Aeropac Team's rocket, we will be using one of the school's venerable RDAS-Tiny's for apogee detection and primary deployment. The deployment charge will either be a CD3 or a machined O-ring sealed powder charge of several grams-to be determined. I'm leaning to the charge, because AFAIK, no CD3 has ever successfully fired at >>50kft. Our backup deployment is TBD; we are hoping to demo the (relatively) new AIM XTRA GPS-based apogee detection system, which *should* be the best option of any hobby computers based on the market now, but has never been tested in a rocket of any performance whatsoever. If this eventuality happens we will use the RDAS accel-based apogee as a backup.

We do not yet know when or where we will complete the flight. It will take at least a month or so before we are ready with the new nosecone and anchor. Given recent events, I am strongly leaning toward Aeropac; their professionalism, competency, and hospitality were exemplary. We would be honored to return to the Black Rock playa sometime in the near future.

So what is your expected altitude?

This project never ceases to amaze me. Thanks for sharing it.

Would you consider flying this at LDRS this year at black rock? I would absolutely love to see this fly.

Alex

Ahh yes, that's probably another interesting consideration.

As you probably noticed in the full stack render, there is no tailcone. We have decided that the tailcone shouldn't make a big difference. The rocket spends almost no time in flight regimes where a tailcone should really effect the flight. Tailcones are essential for low drag in subsonic and transonic flight, but as the mach number rises, the effect of tailcones on CD should vanish. We believe that Erroneous calculations based on our tailcone in RASAero were partly responsible for our very high altitude prediction before. It also gives more margin to play with stability, which was necessary since we've shedded 6 inches overall with this revision.

All things said and done, however, RASAero still yields an apogee in the 90,000' range when launched from Black Rock. This is with intentionally conservative inputs with regard to the bevel on the fincan, the sharpness of the nose and fins, and the surface smoothness condition (camo paint selected). When we enter correct values for the fin/nose tip radii and the surface condition, we simulate to ~105,000'. In both cases we max out at roughly Mach 4.12, with about 10-12 seconds above Mach 3.

Part of our decision with regards to flight date is going to depend on if the true purpose of the project is met; namely, to help CarVac and I find employment or graduate school admission. Our ideal time to launch would either be at LDRS Black Rock, or to return to XPRS. I am open to Mudroc/Aeronaut based on convenience in my, CarVac's, and our mentor Greg Lyzenga's schedules. That preference might shift if it turns out that the N5800 record contest is extended to 2013.

To be clear, we don't want to have to deal with potential extremely low temperatures reducing the pressure of the CD3's CO2 cartridge below a useful level.

VERY cool. Thanks so much for "taking us along for the ride" here on the forum as this project continues/develops. I've been thoroughly enjoying it so far, and can't wait for more. And I'm really rooting for success in the sky.

s6

Additionally, we intend to (like Don't Debate This) test out the recovery system beforehand with a 4" ~K-powered stand-in for the 98/6GXL, though we won't be flying the actual fincan (unlike Don't Debate This).

That should be fun to make, especially since it has to have approximately the same mass and mass distribution as a burned-out N5800, with a similar fin profile. We're thinking of a single 48" piece of 4" Blue Tube coupler, with a bunch of slugs of aluminum that we have floating around the clubroom VERY firmly mounted inside.

Look forward to build details on that too!

Has anyone tried the disposable hand/foot warmer packets to keep CO2 cartridges
or battery packs from the cold at extreme altitudes?

Always thought this may be a lo-tech approach to a common problem.
Disregard if previously discussed.

It has been used in the past-we were generously given some at XPRS to use, as we had neglected to plan for active heating. This time I think I will have an active heating element running off of a non-flight battery in the avionics bay, in addition to considerable insulation surrounding it.

reeves said:

Has anyone tried the disposable hand/foot warmer packets to keep CO2 cartridges
or battery packs from the cold at extreme altitudes?

Always thought this may be a lo-tech approach to a common problem.
Disregard if previously discussed.

Click to expand...

Not discussed here, but at our first launch attempt at XPRS. Apparently they work alright for keeping batteries alive on balloon flights, so at least new ones should be effective.

I was hesitant about it on our first attempt for several reasions. 1. We had no space set aside for them, and 2. We (I in particular) worried about overpressurizing the CO2 cartridge. I tried some from the pack I had brought along, and they were kinda weak (given they were two years old), so I stuck one in on top of the CO2 cartridge in its tube, but I don't expect it would have had much of an effect either way.

In any case, the CD3 is extremely bulky (wide!) for a given amount of ejection force, not great for such a compact rocket like this one. Our redesign is even smaller than the original, making it a questionable inclusion, especially when black powder charges in latex tubing have been used successfully after extended exposure to near-complete vacuum.

CarVac said:

In any case, the CD3 is extremely bulky (wide!)
.

Click to expand...

Is that because you are using the gold retaining ring? If so, ditch it.

bandman444 said:

Is that because you are using the gold retaining ring? If so, ditch it.

Click to expand...

We were and are not using the retaining ring

It comes down to this: I could fit two or three GIGANTIC black powder charges into the CD3's volume, with no loss of reliability (and perhaps even gains, given the low-temperature problems with CO2).

Additionally, we lose flexibility of placement. The through-bulkhead mounting of a CD3 would be a tremendous waste of space in our updated design, while a black powder charge can be simply placed in the parachute bay on a long ematch wire, followed by the parachute itself. It could theoretically be done with a CD3, but I don't want a CD3 falling on me at terminal velocity from 90-100,000 feet.

Have you thought of using a z-Pard like device for separation? I have one that is essentially a 3/4" diameter piece of aluminum tube the desired stroke length. I've used them very successfully on a few rockets. I've even almost lofted a brick over a house on the maiden test.

Edward

I saw a really cool product a while ago.. It was a reusable heating pack made of silicone. Www.repeattheheat.com I think it was. The heat packs almost gave me a burn, so they are nice and toasty. I thought this might help.

Yoehahn said:

I saw a really cool product a while ago.. It was a reusable heating pack made of silicone. Www.repeattheheat.com I think it was. The heat packs almost gave me a burn, so they are nice and toasty. I thought this might help.

Click to expand...

The sodium acetate pads? Probably not useful, since they're dependent on the release of heat from the precipitation of a supersaturated solution; after an initial heat release it doesn't stay warm.

Someone waay back when mentioned that they had questions about the launch tower. Sometime tomorrow I'll do my best to post a short blurb about the tower.

CarVac said:

Additionally, we intend to (like Don't Debate This) test out the recovery system beforehand with a 4" ~K-powered stand-in for the 98/6GXL, though we won't be flying the actual fincan (unlike Don't Debate This).

That should be fun to make, especially since it has to have approximately the same mass and mass distribution as a burned-out N5800, with a similar fin profile. We're thinking of a single 48" piece of 4" Blue Tube coupler, with a bunch of slugs of aluminum that we have floating around the clubroom VERY firmly mounted inside.

Look forward to build details on that too!

Click to expand...

You can fly a K1620 (CTI 1 grain V-max) in a 6xl case with 2 forward closures, one at the top of the case and one at the top of the motor. 3" PVC works as a spacer. Not sure what the mass & mass distribution would be like though, as the PVC is probably heavier than the burnt out liner and stuff.

CarVac said:

We were and are not using the retaining ring

It comes down to this: I could fit two or three GIGANTIC black powder charges into the CD3's volume, with no loss of reliability (and perhaps even gains, given the low-temperature problems with CO2).

Additionally, we lose flexibility of placement. The through-bulkhead mounting of a CD3 would be a tremendous waste of space in our updated design, while a black powder charge can be simply placed in the parachute bay on a long ematch wire, followed by the parachute itself. It could theoretically be done with a CD3, but I don't want a CD3 falling on me at terminal velocity from 90-100,000 feet.

Click to expand...

I did an article for Rockets Magazine on high altitude deployment that might be helpful to you. It was in the June 2011 issue.

Jim

xenon said:

You can fly a K1620 (CTI 1 grain V-max) in a 6xl case with 2 forward closures, one at the top of the case and one at the top of the motor. 3" PVC works as a spacer. Not sure what the mass & mass distribution would be like though, as the PVC is probably heavier than the burnt out liner and stuff.

Click to expand...

1. Not really feasible because we only have one 6XL case and it is currently loaded with an N5800, and we're not intending to wrestle the fincan off of it until after it flies.
2. Even if we did, we won't need a second forward closure due to some Secret Sauce attachment methods.
3. We would need access to a research launch to fly that due to using other spacers being uncertified.

CCotner said:

It has been used in the past-we were generously given some at XPRS to use, as we had neglected to plan for active heating. This time I think I will have an active heating element running off of a non-flight battery in the avionics bay, in addition to considerable insulation surrounding it.

Click to expand...

I presume that you'll use a set of thermistors and a battery pack. That would provide a very reliable, high energy heating source with low-complexity and relatively few failure modes.

JordanT said:

I presume that you'll use a set of thermistors and a battery pack. That would provide a very reliable, high energy heating source with low-complexity and relatively few failure modes.

Click to expand...

That is pretty much what I was thinking of. I just need to find one that works on multiples-of-lipo voltages, and maintains room temperature at that...

thread...BUMP

I am pleased to announce our intention to fly Bare Necessities (rev16 lol) at LDRS 32 this summer in the Black Rock Desert. A big thanks to Special Projects Manager MClark for working through design revisions with us!

Now, some goodies:
View attachment AvBayLayout.PDF
View attachment Bare_Necessities_v16.rkt
View attachment ExternalDimentions.PDF
View attachment InternalDetails.PDF
View attachment N5800CS_v16.alx1

View attachment v16_N5800CS_Mach.pdf
View attachment v16_N5800CS_Alt.pdf
View attachment v16_N5800CS_MachDetail.pdf

And, just for fun:

View attachment v16_O3400_Mach.pdf
View attachment v16_O3400_Alt.pdf

In the next weeks, we will begin fabrication of the new top end. I will do my best to keep this updated. We are no longer interested in 'secret sauce methods', and have elected to be as open and forthright about our fabrication as possible. Looking forward to finally seeing this thing fly!

EDIT: I almost forgot! This will also serve as a demonstration flight of Entacore Electronics' AIM XTRA flight computer! This is (as some of you know) a flight computer that detects apogee for deployment purposes through kalman-filtered GPS position (ublox 6) and a combination of high-precision accelerometers. We are excited to demonstrate the potential of this approach for limit-pushing amateur rockets, where many other existing technologies fall short.

https://entacore.com/electronics/aimxtra

USA Dealer: https://www.offwegorocketry.com/

Pics and Vids Please

Oh, there will be. We might-no promises- even be able to fit a GoPro Hero3 Black inside...but that will be subject to the mercy of volumetric and structural concerns, of course.

I was going back on fourth on whether to attend LDRS or not this year. I eventually decided on going and this project was one of the reasons why. I can't wait to see this in real life.
Edit: I will be able to get good video from the ground.

Alex

NICE!

Tony