Rocketarium Trident T222-24 - Build

The Rocketry Forum

Help Support The Rocketry Forum:

new2hpr

Well-Known Member
Joined
Jan 23, 2009
Messages
967
Reaction score
38
Location
Colorado
For the retainer, all you need is that hex standoff, screw, and washer. Why add the time, money, and drag to make the triple-ring thingie? Other than it's fun to design and mill!
 

Eric Nantel - DiaLFonZo

Well-Known Member
Joined
Oct 6, 2019
Messages
117
Reaction score
51
For the retainer, all you need is that hex standoff, screw, and washer. Why add the time, money, and drag to make the triple-ring thingie? Other than it's fun to design and mill!
Well - Because i'm a lot better with a CNC than with my own hands (lol). One still need to glue a matching standoff in the middle and even a 3/16" do not fit and it look so much better (my taste.. ).

Here is the finish result.. False carbon fiber only top and bottom layers but the core is glass fiber, the material was laying around..
 

Attachments

Eric Nantel - DiaLFonZo

Well-Known Member
Joined
Oct 6, 2019
Messages
117
Reaction score
51
Motor fit pretty nicely.
I wonder what people use to coat the inside, making sure the cardboard do not damage over time?
 

kuririn

BARGeezer
TRF Supporter
Joined
Oct 3, 2016
Messages
4,455
Reaction score
1,975
Location
Hawaii
Be careful with all the modifications and additions. You are adding extra weight and potentially changing the CG of the stock rocket.
 

Eric Nantel - DiaLFonZo

Well-Known Member
Joined
Oct 6, 2019
Messages
117
Reaction score
51
Be careful with all the modifications and additions. You are adding extra weight and potentially changing the CG of the stock rocket.
Thanks for the reminder, i really need to watch for that.
I don't think it will be an issue however, the rocket can carry fairly big motors (heavy).

The motor retainer is quite light, don't even pick on my scale.
For the payload bulkhead, a few grams here. The Top 3 tubes bulkhead is glued so cannot weight it but it has larger opening than the stock one and thinner so it might be a gram more.

The "transition" is probably the worst as it doesn't replace anything so pure added weight.
Maybe close to the CG so less of an impact on it and i haven't weight it but CAD say about 6g.

I wonder if i should make the motor stop (in the tubes) in the same material..
 

Attachments

Andrew_ASC

UTC SEDS 2017 3rd/ SEDS 2018 1st
Joined
Sep 22, 2017
Messages
3,869
Reaction score
517
You can add a short body tube of same tube spec diameters of cluster tubes probably and override mass of short body tubes to actual retainer mass. That’s what I did with a Fastback54 retainer on a L2 build for OR but that retainer was really heavy.
 

Eric Nantel - DiaLFonZo

Well-Known Member
Joined
Oct 6, 2019
Messages
117
Reaction score
51
You can add a short body tube of same tube spec diameters of cluster tubes probably and override mass of short body tubes to actual retainer mass. That’s what I did with a Fastback54 retainer on a L2 build for OR but that retainer was really heavy.
I'm not sure I understand the suggestion.
You mean lengthening on the other side of the CG?
 

Eric Nantel - DiaLFonZo

Well-Known Member
Joined
Oct 6, 2019
Messages
117
Reaction score
51
Ok - I had an idea and it will not make everyone happy or excited..
Let me explain what i mean...

- The rocket use a cluster of 3 motors
- So there are 3 ejection charges
- I'd like to channel only one charge to the top for ejection
- Then channel the other two to the sides
- At ejection i'll see 2 side explosions and an ejection

Please.. don't "hate" .. ;)
 

neil_w

Hunkered down and slowly going crazy
TRF Supporter
Joined
Jul 14, 2015
Messages
9,084
Reaction score
2,407
Location
Northern NJ
Ok - I had an idea and it will not make everyone happy or excited..
Let me explain what i mean...

- The rocket use a cluster of 3 motors
- So there are 3 ejection charges
- I'd like to channel only one charge to the top for ejection
- Then channel the other two to the sides
- At ejection i'll see 2 side explosions and an ejection

Please.. don't "hate" .. ;)
No hate, but there is one significant downside: if the one motor that is ducted to the top does not light, then you have... no ejection at all. And that is certainly a possible occurrence.
 

neil_w

Hunkered down and slowly going crazy
TRF Supporter
Joined
Jul 14, 2015
Messages
9,084
Reaction score
2,407
Location
Northern NJ
If the motor in a single-motor rocket does not light, then the rocket does not go up, and therefore will also not come down, ballistic or otherwise. :)

This is a unique characteristic of cluster rockets.

[never mind, seems you got it on your own.]
 

Eric Nantel - DiaLFonZo

Well-Known Member
Joined
Oct 6, 2019
Messages
117
Reaction score
51
If the motor in a single-motor rocket does not light, then the rocket does not go up, and therefore will also not come down, ballistic or otherwise. :)

This is a unique characteristic of cluster rockets.

[never mind, seems you got it on your own.]
See my post just above [emoji1787]
Initially I taught that the ejection charge only would fail.

Good advice.. Might not be a so great ideas.
 

neil_w

Hunkered down and slowly going crazy
TRF Supporter
Joined
Jul 14, 2015
Messages
9,084
Reaction score
2,407
Location
Northern NJ
Good advice.. Might not be a so great ideas.
I think there's much more to be lost than gained by doing it.

I haven't done much cluster flying, but just from hanging out here I can see that a lot of consideration goes into accommodating failed ignitions, where less than the full number of motors starts. There are a lot of "interesting" failure modes and consequences. In general, if you have a rocket that is likely to fail catastrophically if any one motor doesn't light, then you should change your plans.
 

Eric Nantel - DiaLFonZo

Well-Known Member
Joined
Oct 6, 2019
Messages
117
Reaction score
51
I think there's much more to be lost than gained by doing it.

I haven't done much cluster flying, but just from hanging out here I can see that a lot of consideration goes into accommodating failed ignitions, where less than the full number of motors starts. There are a lot of "interesting" failure modes and consequences. In general, if you have a rocket that is likely to fail catastrophically if any one motor doesn't light, then you should change your plans.
It does make sense and I'm happy I've dropped the idea here before doing it. [emoji106]
 

Tyler P

Nom-nom-nom...
TRF Supporter
Joined
Oct 2, 2018
Messages
618
Reaction score
209
Well - Because i'm a lot better with a CNC than with my own hands (lol). One still need to glue a matching standoff in the middle and even a 3/16" do not fit and it look so much better (my taste.. ).

Here is the finish result.. False carbon fiber only top and bottom layers but the core is glass fiber, the material was laying around..
Looks pretty trick!
 

Tyler P

Nom-nom-nom...
TRF Supporter
Joined
Oct 2, 2018
Messages
618
Reaction score
209
Ok - I had an idea and it will not make everyone happy or excited..
Let me explain what i mean...

- The rocket use a cluster of 3 motors
- So there are 3 ejection charges
- I'd like to channel only one charge to the top for ejection
- Then channel the other two to the sides
- At ejection i'll see 2 side explosions and an ejection

Please.. don't "hate" .. ;)
I was thinking the same thing. You could just run two plugged motors and one with a recovery charge.

Having never flown a cluster before, how does one deal with all three charges? Do you just let it go with all three charges or what?
 

kuririn

BARGeezer
TRF Supporter
Joined
Oct 3, 2016
Messages
4,455
Reaction score
1,975
Location
Hawaii
I just run with all three ejection charges. Redundant backup if one motor fails to light. Also not uncommon for the charges to pop a split second apart from each other. So overpressurization of the main motor tube is mitigated. I haven't had a tube split from the ejection charges yet.
 

Tyler P

Nom-nom-nom...
TRF Supporter
Joined
Oct 2, 2018
Messages
618
Reaction score
209
I just run with all three ejection charges. Redundant backup if one motor fails to light. Also not uncommon for the charges to pop a split second apart from each other. So overpressurization of the main motor tube is mitigated. I haven't had a tube split from the ejection charges yet.
Excellent. I was wondering about the pressure. Good to go on all three, then.
 
Top