2.6” Nike/Arcas style high power two-stage

[rfjustin]

Inspired by some fine two-stage action at Airfest 26 (2020) in KS over Labor Day weekend, I cooked up a preliminary design in my head for a 2.6” diameter two-stage, 54mm mounts in both top and bottom. (4) Nike style fins for booster, (4) Arcas style fins for sustainer. This is not meant to be scale in any way, just a sporty two stage that should be able to stretch its legs a bit in KS next year.

Overall length will be kept minimal, but not painfully so. Max motor for both top and bottom will be the AT 2800/CTI 6XL. Intended motor combo for Airfest 27 (2021) is an AT L-1090 to AT K-250. Booster components are on order from Mach 1 rocketry, and other orders need to be placed to PerfectFlite, Missile Works, Wildman, Additive Aerospace, and Featherweight.

Sustainer will be head-end dual deploy, with Missile Works RRC3 and Featherweight Raven 4 for deployment back-up and lighting of the sustainer motor intelligently. Booster will be single deploy from an RRC3, plus PerfectFlite timer to fire a small separation charge.

This is a less than typical build thread for me as I usually don’t begin a build thread until I have all the parts in hand, but this will be a work in progress over the fall/winter, so here goes. I’m very much looking forward to seeing what Mach 1 Rocketry delivers in the near(ish) future. Fins are also on order, more to come…

 

[mo2872]

Following.......

 

[Nytrunner]

What's your expected altitude? That's going to get UP there

 

[rfjustin]

What's your expected altitude? That's going to get UP there

Have not simmed it yet, but guessing 30-40K depending on many factors.

 

[Eric]

That will be an amazing flight. Looking forward to seeing your interstate coupler design.

 

[rfjustin]

That will be an amazing flight. Looking forward to seeing your interstate coupler design.

Nothing fancy, just glass coupler that will slide into sustainer, avionics contained inside said coupler for booster deployment as well.

 

[rfjustin]

Fins arrived and passed them over the router with good results.

 

[rfjustin]

 

[rfjustin]

Was able to grab test flight motors and Airfest 2021 motors today from Wildman.

 

[rfjustin]

Some parts beginning to arrive...

 

[David_Stack]

'passed them over the router with good results...' I'll say. That looks fantastic!

Would be curious to gain a better understanding of how you did that work. CNC, or otherwise? If your process has been addressed in a prior thread, a hint on where to look would be greatly appreciated.

 

[rfjustin]

'passed them over the router with good results...' I'll say. That looks fantastic!

Would be curious to gain a better understanding of how you did that work. CNC, or otherwise? If your process has been addressed in a prior thread, a hint on where to look would be greatly appreciated.

https://www.rocketryforum.com/threads/wildman-mach-3.158888/#post-1988355
https://www.rocketryforum.com/threads/glasspacks-lvl-ii-build.157524/page-2#post-1993094

 

[crossfire]

Some parts beginning to arrive...
View attachment 433438View attachment 433439

How did you slot the tubes?

 

[TimothyG]

I can't believe you found a K250. I've been looking for a year now with no luck. Any chance your source has another?

 

[Cameron Anderson]

I can't believe you found a K250. I've been looking for a year now with no luck. Any chance your source has another?

Wildman has them. Got one myself.

 

[rfjustin]

All Mach 1 glass parts are now in, time to really map this thing out and make some tube cuts.

 

[Cameron Anderson]

All Mach 1 glass parts are now in, time to really map this thing out and make some tube cuts.

View attachment 435118

How long are those motor mounts?

 

[rfjustin]

36" currently, they will be cut down to 26-27"

 

[rfjustin]

Shout-out to Ian D. from Badass Rocketry for getting me set up with proper fin thickness 2.6" guides. Now we can really think about putting pen to paper in the next couple months.

 

[rfjustin]

With a sigh, project has been abandoned.... the 2.6" thin walled components are not going to be able to handle the stresses involved without double walling every coupler and airframe. I'm just going to pivot to a 3" airframe, both with 54mm holes for some two stage fun. I have to build something to use the motors already purchased!

 

[Nytrunner]

Whats the breaking point of the thin wall stuff?

 

[rfjustin]

Whats the breaking point of the thin wall stuff?

To be honest, I'm not sure what the breaking point would be, but I don't really want to find out. What gave me pause and concern was the amount of noticeable flex in the thin wall stuff.

I think the components would be great for a small, lightweight head-end bird (building it now with the Arcas style sustainer fins) without too much concern of it folding, but we shall see.

 

[Jee3300R]

I think the Thinwall would have been fine with a good coupler fit and overlap. But a 3” to 3” two stage will be much more convenient and will put in nice high flights to 20-25k on the right motors.

 

[plugger]

Sustainer will be head-end dual deploy, with Missile Works RRC3 and Featherweight Raven 4 for deployment back-up and lighting of the sustainer motor intelligently. Booster will be single deploy from an RRC3, plus PerfectFlite timer to fire a small separation charge.

Hey Justin, won't you need to use tilt inhibit? Not trying to cause difficulties, just more hoping you don't rock up to launch and be told no as your electronics don't support tilt inhibit.

In the US, angle lockouts are required by both NAR & TRA for multi-stage flights.

 

[rfjustin]

Hey Justin, won't you need to use tilt inhibit? Not trying to cause difficulties, just more hoping you don't rock up to launch and be told no as your electronics don't support tilt inhibit.

Can you post the link that Johnly referenced please? "In the US, angle lockouts are required by both NAR & TRA for multi-stage flights."

Thank you,

 

[rfjustin]

Hey Justin, won't you need to use tilt inhibit? Not trying to cause difficulties, just more hoping you don't rock up to launch and be told no as your electronics don't support tilt inhibit.

I believe Johnly 's reference is not accurate. There is no specific reference to "angle lockouts" aka tilt inhibit for multi-stage flights published on TRA's website, unless I missed something.
https://www.tripoli.org/Portals/1/Documents/Safety Code/Range Safety Guidelines v1.3.pdf


· Make sure that none of the HPR motor ignitors are installed until the rocket is at the launch pad.

· Make sure that the rocket will be stable during its entire flight profile: Ask the flier to show the CP of the fully assembled rocket (i.e. all stages assembled). Ask the flier to show the CP of the rocket after each staging event.

· Make sure the booster motor(s) have sufficient power to get the rocket stable.

· Make sure that the electronics to control the staging motor ignition will only be armed once the rocket is on launch position. Make sure that the same electronics can and will be disarmed if the rocket needs to be removed or lower off the launch pad.

· Ask the flier about the delay(s) that are used between staging events. Make sure that the delay is not so long as to happen if the rocket has arced over into an unsafe orientation. Ask to see flight simulation if there is a concern.

· Ask the flier if the stages are expected to “drag separate”, or is there a separation charge to initiate separation prior to sustainer ignition. Depending on the location of the staging electronics (sustainer vs. inter-stage coupler), premature separation could prevent sustainer motor ignition.

· If the sustainer motor is used to initiate stage separation, check to make sure that the blast from the sustainer motor will not damage the booster’s ability to safety recover.

· The upper stage(s) of HPR rockets must be using electronic recovery, and not rely on motor ejection.

· If required, make sure that the staging electronics have a feature to inhibit staging events if the rockets flight profile does not follow expected behavior.

 

[SparkyVT]

I believe tilt-lockout is only required for Class 3 flights:

https://www.tripoli.org/C3RC

 

[plugger]

I believe Johnly 's reference is not accurate. There is no specific reference to "angle lockouts" aka tilt inhibit for multi-stage flights published on TRA's website, unless I missed something.

Thanks for clarifying Justin. Obviously I don't have any skin in the game so to speak but it's good to know how y'all handle it on the other side of the fence.

· Make sure that none of the HPR motor ignitors are installed until the rocket is at the launch pad.

I'm struggling how this rule works with HEI. Does it imply that a HEI stustainer motor isn't to be assembled until the flyer is at the launch pad?

· If the sustainer motor is used to initiate stage separation, check to make sure that the blast from the sustainer motor will not damage the booster’s ability to safety recover.

I'm not sure how one is meant to do this without doing it. I've successfully lit a sustainer motor via the booster twice in high power staging attempts and both times I thought the booster's av bay would be fine. Both times I was wrong.