Pushing an LPR as a MPR upper stage

[Charles_McG]

I've built a 1/5.5 scale Nike Apache out of an Estes PSII Nike Smoke and sundry custom parts. The Apache is essentially a low power rocket - BT55 and BT60 with a 24mm motor mount.

So as I prep for two stage flights, I'm wondering just how far I can push that Apache. Careful motor choose keeps it subsonic, but still hits about 45G. Can BT55 take it? Do I have a testing option? I've got some spare parts, I've though about setting up the body tube and transition and simply setting 50 times the payload weight on top of it.

Any other ideas?

 

[Sooner Boomer]

One really big problem is that your booster stage will probably be stable after staging (because there is a long body tube in the booster, not just a short tube and a set of fins). This means it will come down (possibly at considerable velocity) and try to core sample whatever's under it. You can fix this by 1) building in some sort of recovery/drag device like a parachute or streamer that's deployed on staging, or 2) carefully plan out the CG of each stage so that the booster is unstable, but the combined stages are stable. I think there's a thread from a few years ago discussing this rocket and this problem.

 

[Charles_McG]

Thanks Sooner. That's addressed and tested already. The booster is a near stock Nike Smoke with a sandman-turned interstage for the nose cone. Yes, the booster is stable - and flying on composite motors. So it will come down after motor ejection and likely with a chute release. Tested last weekend as a boosted dart - flew beautifully, though the stages didn't part by drag like I though they would.

I've even mitigated the known weakness of the Estes PSII Nike Smoke. The fins are foam filled and leading edges taped to prevent air wedging.

Nope, my current concern is just how far can I push the upper stage. Can I really put a G65 in it? Or a G107 Dual thrust - which has better delay options for this flight. Or will the initial thrust at 45-60G crumple my poor Apache?

 

[CPUTommy]

I vote trial by fire... push the button and report back the findings..

 

[Charles_McG]

Ok, following the method outlined on a couple other threads here in TRF, I've calculated the load due to drag and the load due to payload mass for a couple points along the Apache summed flight - Vmax and the end of the main part of the burn.

It looks like a 12lb axial load on the sustainer airframe for the G65 and 16 lbs for the G107.

Instead of trying to calculate the tubing strength, I'll just test it empirically. 15-20lbs is doable.

 

[RIB]

Why not run a length of BT-55 coupler tube up the Apache........leaving room for both the engine mount and the nose cone of course

 

[Charles_McG]

I might end up doing that.

Here's a pad pic from the full electronics test flight - but with a plug instead of the upper stage motor.

 

[Sooner Boomer]

How are you lighting the upper stage?

 

[Charles_McG]

There's an Eggtimer Quantum and an Eggfinder built into the Apache's payload transition, with wire conduits running down the inside to the base of the motor mount.

 

[Charles_McG]

BT55 is tougher than I thought. I don't think I'll have any structural problems after all.

 

[Wallace]

BT55 is tougher than I thought. I don't think I'll have any structural problems after all.

View attachment 324997
View attachment 324998

I'd love nothing more than to see this work. Just keep in mind that there are forces acting on the structure as a whole that can and will be unpredictable, I.E weather/wind shear/balance. Hopefully the stars align and you get some wonderful video. I'd love to see it happen and am close enough to possibly be there for the launch. I'll be following this one.

 

[Tonimus]

I don't think you'll have an issue as long as the rocket has radial symmetry. Having anything uneven will increase the side loading on the tube.

 

[Charles_McG]

I'd love nothing more than to see this work. Just keep in mind that there are forces acting on the structure as a whole that can and will be unpredictable, I.E weather/wind shear/balance. Hopefully the stars align and you get some wonderful video. I'd love to see it happen and am close enough to possibly be there for the launch. I'll be following this one.

It calls for a calmish day, certainly. The single stage test flight was maybe my straightest to date.

Wallace, do you tend to frequent TWA over WOOSH - or versa vice? I try to make all that I can - but WOOSH on Sunday is easier for me to escape the tasting room (1 mile straight north of the launch area) without putting undue strain on my wife. The next TWA launch, I'll be at the Great Taste in Madison. So I'll try to fly a ECOF - though probably not a full impulse flight. I'm building up gradually.

If I try to sneak out for a between-club flight, as I see you do, I just launch from the back corner of the orchard. Which is what we do in Oct/Nov, after the row crops are in - and the clubs stop flying for various hunting seasons.

And Tonimus - it's very symmetrical. Not even a launch lug on the sustainer. I'm not going to try for flight video - unless I put something on the booster. Hmm... one camera up and one down would be symmetrical

 

[BDB]

It calls for a calmish day, certainly. The single stage test flight was maybe my straightest to date.

Wallace, do you tend to frequent TWA over WOOSH - or versa vice? I try to make all that I can - but WOOSH on Sunday is easier for me to escape the tasting room (1 mile straight north of the launch area) without putting undue strain on my wife. The next TWA launch, I'll be at the Great Taste in Madison. So I'll try to fly a ECOF - though probably not a full impulse flight. I'm building up gradually.

If I try to sneak out for a between-club flight, as I see you do, I just launch from the back corner of the orchard. Which is what we do in Oct/Nov, after the row crops are in - and the clubs stop flying for various hunting seasons.

And Tonimus - it's very symmetrical. Not even a launch lug on the sustainer. I'm not going to try for flight video - unless I put something on the booster. Hmm... one camera up and one down would be symmetrical

I'm planning to do something similar this weekend. I made a booster for my BT60 Estes Magnum clone. It's maiden flight will be F23-4-->C11-7, with an Eggtimer Quantum lighting the sustainer and motor eject for the booster's recovery deployment. I'm trying to keep everything under 2k ft so I can see the whole flight profile. I'm just hoping for cooperative weather on Saturday.

Good luck with your flight.

 

[Charles_McG]

And good luck with yours.

What igniter are you using for the C11? My Quantum won't light the orange Estes PS ingiters. I haven't tried the solars, or older black tipped LPR Estes igniters (though Cris says he does test with them.)

 

[djs]

And good luck with yours.

What igniter are you using for the C11? My Quantum won't light the orange Estes PS ingiters. I haven't tried the solars, or older black tipped LPR Estes igniters (though Cris says he does test with them.)

Have you tried the Quest Q2G2? People seem to swear by them (instead of at them).

 

[BDB]

And good luck with yours.

What igniter are you using for the C11? My Quantum won't light the orange Estes PS ingiters. I haven't tried the solars, or older black tipped LPR Estes igniters (though Cris says he does test with them.)

I'm hoping to use an e-match. I know that the quantum will light it, and they are so much more reliable than Estes igniters. I use them exclusively for lighting BP E and F motors now. I just need to figure out how to attach it to nozzle. I've heard that you can just tape it to the bottom of the motor, but I haven't tried that yet. If that doesn't work, I have a stash of a few Q2G2s.

 

[Charles_McG]

Have you tried the Quest Q2G2? People seem to swear by them (instead of at them).

People like the old Q2G2s, Glen. Got any? They are a teensy bit scarce these days. I'll use an ematch - Tim's have worked for me to date.

I'm thinking F79 to D9 for the next flight. I'll have to see what fits in the D9 - but I have some of the skinny First Fire <strike>Jrs <\strike> Minis.

From my pre-BAR days, I recall motors coming with tape dots to hold the igniter in place. They worked. So did masking tape if the dots wouldn't stick.

 

[terryg]

These seem to be available. I have not tried them yet.

https://electricmatch.com/rocketry/see/23/6/bp-rocket-starter

 

[Wallace]

People like the old Q2G2s, Glen. Got any? They are a teensy bit scarce these days. I'll use an ematch - Tim's have worked for me to date.

I'm thinking F79 to D9 for the next flight. I'll have to see what fits in the D9 - but I have some of the skinny First Fire <strike>Jrs <\strike> Minis.

From my pre-BAR days, I recall motors coming with tape dots to hold the igniter in place. They worked. So did masking tape if the dots wouldn't stick.

I just so happen to have a few. If we can somehow make our schedules work I'd be happy to donate for the cause..

 

[Charles_McG]

Thanks Wallace.

In off-forum conversation with Cris, I'm becoming more convinced that my 20C lipos aren't up to snuff - except for low current e-matches.

 

[Wallace]

I was speaking of Q2G2's, the short ones if they could possibly help? I would assume that lipo would be fine.

 

[Charles_McG]

I've got a cluster or two that would benefit from them . Like my Titan IIIe. C11-0s in the boosters. And I just got some F10s. Just the thing for the core. But, boy-oh-boy, everything had better light on the pad!

 

[Charles_McG]

Were I planning on using a black powder motor in the upper stage, I'd also take you up on that offer, right away. But I'm think composite at the moment.

 

[Wallace]

Gotcha, didn't realize what exactly it was you were attempting. I'd love to see that work.

 

[Charles_McG]

Maybe at ECOF. We'll see.

 

[Wallace]

I hope to be there.......But Life may once again deny me.

 

[Wallace]

Btw, I'm scheming on building this out of my "crashed" pile of parts. ..

 

[Wallace]

Progress report ?

 

[Charles_McG]

Ordered the 45C 300mah Turnigy Lipo that Cris recommends, is all. And spent some time making fins to replace the ones missing on my 1/100 Saturn 1B kit. And asked Jackie to hold motors for my for ECOF. And poured cider for the 6000 attendees at The Great Taste of the Midwest.