Booster Shot: another dubious build thread

[BABAR]

Did I miss the masses of the “as built”.sustainer alone and the full stack?

Your C11-0 booster is rated at 6 ounces max lift off, your sim file puts the stack at 4.54 ounces, so unless you were heavy on paint, you should get off the rod with authority. Plus it eyeballs far las draggy than some of your creations.

Concur with @lakeroadster , your vents are nicely placed and that is a reeeaaallly short gap. Seems like overkill, but I use a red sharper on the nozzle end of the casings of the zero delay motors so I can confirm right up to launch that I put the right motor in. don’t as how I know this.

Going with an A10-3 in sustainer gives you a larger sustainer bore for the booster to target. Not sure how that effects apogee ejection speed.

In any case, short of putting an empty motor casing , a non zero delay booster motor, OR putting the sustainer motor in BACKWARDS (yup, I’ve done them all - I’ve done a LOT of BP STAGING) staging won’t be a problem.

Bring an alcohol pad to wipe down the rail before the shot. Gloves would be a nice touch for the pad loading pictures.

And check your range box for your camera and everything. You don’t want anything left behind.

 

[neil_w]

Did I miss the masses of the “as built”.sustainer alone and the full stack?

You did not, because I didn't post it.

Sustainer dry weight: 2.65 oz
Booster dry weight: 0.65 oz
Total: 3.3 oz

With C11-0 + C6-3: 5.36 oz
With D12-0 + C6-3: 5.62 oz

Obviously smaller motors will weigh less. My goal for first two-stage flight would be C11-0 -> A8-3 or B6-4 (only about 100' difference in apogee).

Seems like overkill, but I use a red sharper on the nozzle end of the casings of the zero delay motors so I can confirm right up to launch that I put the right motor in. don’t as how I know this.

Not a bad idea. I like the idea of putting motor labels around the nozzle end of every motor, so you can always verify exactly what's loaded up. I wish motor manufacturers would do that (at least, for Estes and Q-jets, where it would make the most sense).

The two most important things I need to remember for this rocket are (a) verify booster/sustainer coupling stickiness, and (b) retain the booster motor, either friction or tape. I did forget to tape the motors in my Deuce's Wild once, was very thankful the rocket survived that one.

 

[jqavins]

Bring an alcohol pad to wipe down the rail before the shot. Gloves would be a nice touch for the pad loading pictures.

I love it! Mind you, an alcohol wipe of the rod is never a bad idea anyway.

As for the rest, I agree with the group that you'll be fine. But there's nothing wrong with cautious steps if that's what feels right.

 

[BABAR]

Obviously smaller motors will weigh less. My goal for first two-stage flight would be C11-0 -> A8-3 or B6-4 (only about 100' difference in apogee).

Is there much difference in the velocity at ejection? I’ve always been a fan of smaller sustainer motors for sport rocket flights where altitude isn’t really a goal. And I’m more than happy with my success rate. I don’t run sims, I guess smaller motors may have either a suboptimally early or late sustainer ejection even than more technically “right sized” motors that may better achieve a near zero velocity ejection event.

.


The two most important things I need to remember for this rocket are (a) verify booster/sustainer coupling stickiness,

Again concur with @lakeroadster that you don’t want any angular or lateral “slop” in the coupling, but as for longitudinal slop:

Backward slop of the sustainer should be zero, as something should be butted against something (usually sustainer body tube to booster body tube, around the coupler. Should be a non-issue.)

“forward slop” can be defined essentially as resistance to the separation of the booster and sustainer, or “how tightly or loosely” the coupler joint is to relative FORWARD motion of the sustainer. For BLACK POWDER staging, this should be near 100% (put differently, little or no resistance to forward separation.

Rational:

This is “BLACK POWDER”, not electronic. It is as near instantaneous* as you can get, there is no drag separation.

Properly vented, the booster is NOT going to “blow off” the sustainer before the sustainer ignites. It MAY Fall off before ignited sustainer comes up to full power due to drag, but if anything that’s a good thing.

Most commonly I think black powder separation occurs when booster is BLOWN OFF the sustainer. In this likely most common case, the longer it takes to loose the booster (the “stickier” the coupling in this specific longitudinal vector) the more likely you are to barbecue the forward end of the booster. I’ve seen this a lot mainly in minimum diameter BT5 stagers, I think the “grip” is a bit tight, but hard to loosen without lateral or angular slop.

The downside of a “loose” forward slop is not in flight, it’s in getting the darn thing on the pad in one piece. You have to be careful carrying it to the pad and sliding it down the rail.

In summary, the joint shouldn’t be any firmer to forward separation than a low power nose cone in a properly vented rocket.

*Instantaneous Ignition— yes I know it is not truly instantaneous, but in terms of the physics involved, ignition should occur far faster than the parts can physically separate PROVIDED the system is properly vented.

 

[PhilC]

Reminds me a bit of my post-covid rocket 'Per Ardua ad Astrazeneca'.
https://fogrocketry.bmfa.club/media/gallery

 

[BABAR]

Reminds me a bit of my post-covid rocket 'Per Ardua ad Astrazeneca'. View attachment 664986
https://fogrocketry.bmfa.club/media/gallery

For those of us less erudite.

Per ardua ad astra is a Latin phrase meaning "through adversity to the stars

I wanted to make sure everyone got this in the end.






(Can I get booted for re-using the same jokes? I always want to work at Disneyland on the Jungle Cruise……)

 

[neil_w]

Is there much difference in the velocity at ejection? I’ve always been a fan of smaller sustainer motors for sport rocket flights where altitude isn’t really a goal. And I’m more than happy with my success rate. I don’t run sims, I guess smaller motors may have either a suboptimally early or late sustainer ejection even than more technically “right sized” motors that may better achieve a near zero velocity ejection event.

They're both about equal... assuming the sim is accurate.

Again concur with @lakeroadster that you don’t want any angular or lateral “slop” in the coupling, but as for longitudinal slop:

Backward slop of the sustainer should be zero, as something should be butted against something (usually sustainer body tube to booster body tube, around the coupler. Should be a non-issue.)

“forward slop” can be defined essentially as resistance to the separation of the booster and sustainer, or “how tightly or loosely” the coupler joint is to relative FORWARD motion of the sustainer. For BLACK POWDER staging, this should be near 100% (put differently, little or no resistance to forward separation.

Rational:

This is “BLACK POWDER”, not electronic. It is as near instantaneous* as you can get, there is no drag separation.

Properly vented, the booster is NOT going to “blow off” the sustainer before the sustainer ignites. It MAY Fall off before ignited sustainer comes up to full power due to drag, but if anything that’s a good thing.

Most commonly I think black powder separation occurs when booster is BLOWN OFF the sustainer. In this likely most common case, the longer it takes to loose the booster (the “stickier” the coupling in this specific longitudinal vector) the more likely you are to barbecue the forward end of the booster. I’ve seen this a lot mainly in minimum diameter BT5 stagers, I think the “grip” is a bit tight, but hard to loosen without lateral or angular slop.

The downside of a “loose” forward slop is not in flight, it’s in getting the darn thing on the pad in one piece. You have to be careful carrying it to the pad and sliding it down the rail.

In summary, the joint shouldn’t be any firmer to forward separation than a low power nose cone in a properly vented rocket.

*Instantaneous Ignition— yes I know it is not truly instantaneous, but in terms of the physics involved, ignition should occur far faster than the parts can physically separate PROVIDED the system is properly vented.

Slop and/or excessive looseness will not be a problem. I need to make sure it is not sticky and will release cleanly.

 

[neil_w]

Reminds me a bit of my post-covid rocket 'Per Ardua ad Astrazeneca'.
https://fogrocketry.bmfa.club/media/gallery

Nice, and a fantastic name.

 

[BABAR]

Nice, and a fantastic name.

Yeah. Moderna or Pfizer wouldn’t have worked nearly as well.

Now, “Per Ardua ad Asstra……”

 

[billpr]

Done. Well, close enough... I'll have to steal a 12" parachute from another rocket when needed.
View attachment 664688

Done.
View attachment 664690

Done.

Sanded off the paint on the front centering rings (I had meant to mask those off before painting but forgot), and found that a bit of talcum powder is enough to make for a smooth release.
View attachment 664691

I also applied Future on all the decals.

And that makes it official. Up it goes...
View attachment 664693

Nice group of rockets. Your work really impresses me. Thanks for posting.

 

[PhilC]

Reminds me a bit of my post-covid rocket 'Per Ardua ad Astrazeneca'.

For those of us less erudite.

Per ardua ad astra is a Latin phrase meaning "through adversity to the stars

I wanted to make sure everyone got this in the end

Its also the motto of the Royal Air Force is which I had the honour to serve.

 

[ljwilley]

Done. Well, close enough... I'll have to steal a 12" parachute from another rocket when needed.
View attachment 664688

Done.
View attachment 664690

Done.

Sanded off the paint on the front centering rings (I had meant to mask those off before painting but forgot), and found that a bit of talcum powder is enough to make for a smooth release.
View attachment 664691

I also applied Future on all the decals.

And that makes it official. Up it goes...
View attachment 664693

What is the one on the wall that is black and green with crazy twisty fins? I like that idea!

 

[neil_w]

What is the one on the wall that is black and green with crazy twisty fins? I like that idea!

https://www.rocketryforum.com/threads/starship-avalon-build-thread.136389/