Lets talk about Staging LPR vs MPR and/or clustering

The goal of my rocketry program has always been higher and faster.

My latest sport rocket design, the Icarus 3, according to OR, hits an apogee of 2200 ft, at mach 0.56 on a C6-7. I think that pretty much tops out what you can do w/ single stage LPR. Its predecessor Icarus 2, did 2000 ft at Mach .052, and on its first high altitude attempt, was never heard from again. (that is why I name these things Icarus).

Of course, the solution to losing rockets is GPS Telemetry and/or 2 stage recovery, fine. That stuff weighs 22+ grams. By the time I add all that to a single stage LPR, I get an Ap of 500ft, and at that Ap I don't need any of it.

Now if I'm going to need and be able to use an Eggtimer or whatever, I'm going to have to finally go to multi stage rockets. I know The Rocket Equation!..... (exists). I don't know the math, but I do get the concept that there's a best "mass ratio" (?) between the various stages and that roughly each stage ends up being 2 to 3 times the size of the previous stage (i.e. the Saturn V or Falcon Heavy).

In multistage LPR we don't do that, we just tack on another engine mount and fin assembly and call that a stage.But shouldn't we? Shouldn't top stages run on 13mm engines?

I have noticed Estes sells "booster kits" that are 24mm and that opens the MPR can of worms.

These D and E engines are much more expensive to begin with and by the time you factor in the HazMat fee they're ludicrous. And as I look at these MPR kits in the Estes catalog, they don't go any higher or faster than LPR kits. (MPR really does not interest me) Wouldn't clustering Cs do the same thing?

So I'm going start dabbling in multistage w/ a simple LPR 2 stager. but later I want to add a 3rd booster and that should be MPR or clustered LPR (or... what?)

I'll just say this: I fly LPR almost exclusively, and I don't consider D's and E's to be MPR at all. So I kind of disagree with your assertion that 24mm booster kits "open the MPR can of worms". In fact, D12s are by far my favorite motor to fly, and Aerotech E15s are great too. D motors do not incur hazmat fees, nor do Aerotech E15s. BP E and F engines do incur hazmat charges, which is why I rarely fly them.

Therefore I consider a D12-0 based booster as a perfectly great thing for a booster. A D12 booster to an 18mm sustainer is a good formula. A cluster of Cs would cost as much or more than the D. Of course, if clustering is your objective, then go for it, but I wouldn't do it just for avoidance of the D.

The reason the MPR kits don't go higher than the LPR kits is that they're bigger and heavier, and Estes is generally listing altitudes for its BP motors which are not nearly the most powerful thing those kits will take. Shove a G in them and they'll get up there.

P.S. Your avatar looks great

I think that the rule of thumb you refer to (relative size of stages) will fall apart for model rocketry because the fuel to airframe weight ratio is so different- LPR to Real Space Rockets.

For LPR, I think you are challenged by liftoff thrust to weight ratio. The usual model rocketry choice would be to buy a bigger motor (unless deliberately doing clusters for effect or self-challenge). There are only so many BP motors available, even moving up to MPR diameters.

So you may end up with a cluster in the booster. Not impossible. Just more failure modes.

BrainlordMesomorph said:

In multistage LPR we don't do that...

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It is not common, but dig around a little, and you will find multi-stage rockets using different diameter motors. ASP sells an 18mm WAC Corporal + 24 mm Tiny Tim (for instance).

jlabrasca said:

It is not common, but dig around a little, and you will find multi-stage rockets using different diameter motors. ASP sells an 18mm WAC Corporal + 24 mm Tiny Tim (for instance).

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Estes Solar Flare was 18mm -> 13mm. There are others, I think.

The current Estes Comanche-3 is 24-18-18. I thought the Mini Comanche-3 was 18-13-13 - but it's 13s all the way up.

Charles_McG said:

The current Estes Comanche-3 is 24-18-18. I thought the Mini Comanche-3 was 18-13-13 - but it's 13s all the way up.

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Interesting...…...that's where you need an A-3-6T

BigRiJoe said:

Interesting...…...that's where you need an A-3-6T

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I put an Estes Fletcher up on an A10-3 last launch, and it definitely wanted a longer delay.

neil_w said:

I'll just say this: I fly LPR almost exclusively, and I don't consider D's and E's to be MPR at all. So I kind of disagree with your assertion that 24mm booster kits "open the MPR can of worms". In fact, D12s are by far my favorite motor to fly, and Aerotech E15s are great too. D motors do not incur hazmat fees, nor do Aerotech E15s. BP E and F engines do incur hazmat charges, which is why I rarely fly them.

Therefore I consider a D12-0 based booster as a perfectly great thing for a booster. A D12 booster to an 18mm sustainer is a good formula. A cluster of Cs would cost as much or more than the D. Of course, if clustering is your objective, then go for it, but I wouldn't do it just for avoidance of the D.

The reason the MPR kits don't go higher than the LPR kits is that they're bigger and heavier, and Estes is generally listing altitudes for its BP motors which are not nearly the most powerful thing those kits will take. Shove a G in them and they'll get up there.

P.S. Your avatar looks great

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Thanks
That was helpful.

I was under the misconception that 24mm = D and E = mid power = hazmat fees.
Mainly I guess because all those things are equally new to me.

So I thought that as soon as I installed a 24mm engine mount I was signing up for hazmat fees. I see its a more gradual slope than that.

So now I will build a 24mm booster stage.

Have you looked at Aerotech's Single Use 18mm D21's ?

With over twice the total impulse of an Estes C6, that should send you Icarus 3 on a very fast and very high ride.

..... and no Hazmat!!!!

https://www.buyrocketmotors.com/aerotech-d21-blue-thunder-3-pack-single-use/

I'll probably get "flamed" for this comments, but clustering is only good for the "cool look" factor. Clustering only adds weight. For example, an Estes C6-weighs 26 grams. A D12-5 weighs 43 grams. Add in the extra MMT, and you've put a bunch of extra weight on the wrong end of a rocket. That Aerotech D21 weighs the same as an Estes C6.

If you don't want to get into composite motors, I would look at the Estes CC Express.

https://www.amazon.com/dp/B0006NAKLK/?tag=skimlinks_replacement-20

Just install the thrust ring in the sustainer an additional 1 inch forward in the MMT. This is so you can fly E's in the sustainer. Don't waste you time using D12 in the sustainer. A D12-0 to E9 is a incredible flight.


Alan

If you want to read up on some of the recent threads about staging, check out this thread that I compiled: https://www.rocketryforum.com/threads/2018-the-year-of-multistage-awesomeness.144667/

I haven't curated it much lately. (House construction is sucking all of my time.) But it should give you some ideas about the kinds of cool staging projects that people on TRF are currently working on.

One other comment about composite motors...they are absolutely awesome. I definitely suggest dabbling with them. But if you want to fly a multistage rocket with composite motors, you will need to use electronics to light the second stage. If your goal is to start flying multistage rockets, start with black powder motors.

skip_dye said:

Have you looked at Aerotech's Single Use 18mm D21's ?

With over twice the total impulse of an Estes C6, that should send you Icarus 3 on a very fast and very high ride.

..... and no Hazmat!!!!

https://www.buyrocketmotors.com/aerotech-d21-blue-thunder-3-pack-single-use/

I'll probably get "flamed" for this comments, but clustering is only good for the "cool look" factor. Clustering only adds weight. For example, an Estes C6-weighs 26 grams. A D12-5 weighs 43 grams. Add in the extra MMT, and you've put a bunch of extra weight on the wrong end of a rocket. That Aerotech D21 weighs the same as an Estes C6.

If you don't want to get into composite motors, I would look at the Estes CC Express.

https://www.amazon.com/dp/B0006NAKLK/?tag=skimlinks_replacement-20

Just install the thrust ring in the sustainer an additional 1 inch forward in the MMT. This is so you can fly E's in the sustainer. Don't waste you time using D12 in the sustainer. A D12-0 to E9 is a incredible flight.


Alan

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OMG I had no idea!
I didn't know there are 18mm D's (and 21's no less)!

One of those would take the Icarus 3 past the speed of sound! She's fragile little thing, I'm sure she wouldn't survive.

(I GOTTA GET ME SOME O' THAT)

BDB said:

If you want to read up on some of the recent threads about staging, check out this thread that I compiled: https://www.rocketryforum.com/threads/2018-the-year-of-multistage-awesomeness.144667/

I haven't curated it much lately. (House construction is sucking all of my time.) But it should give you some ideas about the kinds of cool staging projects that people on TRF are currently working on.

One other comment about composite motors...they are absolutely awesome. I definitely suggest dabbling with them. But if you want to fly a multistage rocket with composite motors, you will need to use electronics to light the second stage. If your goal is to start flying multistage rockets, start with black powder motors.

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Thanks that looks like it will be helpful too.

Don't use HazMat as your LPR/MPR line. LokiResearch has HazMat free H and I motors which are clearly in the HPR realm. (I-405 is my fav HazMat free motor)

Personally, I look at building techniques that have to change to support the different thrust profiles. I would consider a D21 MPR and an E-12 LPR because you have to build the rocket stronger to support the higher stress of the D21 vs the lower stress of the E12.

BrainlordMesomorph said:

OMG I had no idea!
I didn't know there are 18mm D's (and 21's no less)!

One of those would take the Icarus 3 past the speed of sound! She's fragile little thing, I'm sure she wouldn't survive.

(I GOTTA GET ME SOME O' THAT)

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D21s have a reputation for removing fins. The 18mm D10 might be a better choice for a low mass and lightly-built rocket.

There will be Quest-branded C and D composites soon (we are assured).

As for the division between mid-power and low power, NAR has this

https://www.nar.org/standards-and-testing-committee/standard-motor-codes/

At our club launches, depending on the rocket, E motors can go from the low power pads.

BrainlordMesomorph said:

The goal of my rocketry program has always been higher and faster.

My latest sport rocket design, the Icarus 3, according to OR, hits an apogee of 2200 ft, at mach 0.56 on a C6-7. I think that pretty much tops out what you can do w/ single stage LPR.

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No, not really.
Throw a few stages together, and you can easily go 3+K ft with low-power rockets. You just should be fully prepared to never see them again.

BrainlordMesomorph said:

Of course, the solution to losing rockets is GPS Telemetry and/or 2 stage recovery, fine. That stuff weighs 22+ grams. By the time I add all that to a single stage LPR, I get an Ap of 500ft, and at that Ap I don't need any of it.

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GPS trackers will assure recovery when you go high enough, but once you add up the weight of the tracker, the battery and the mount, you will be approaching 100g.
2nd/3rd stage will do nothing to help with the recovery, only will make it more challenging to recover all stages of your rocket.

Two very distinct challenges.
In due time, you will likely work your way through both.
Working through them one at a time will be cheaper, and less frustrating, then attempting to tackle both at once.
;-)

BrainlordMesomorph said:

I have noticed Estes sells "booster kits" that are 24mm and that opens the MPR can of worms.
These D and E engines are much more expensive to begin with and by the time you factor in the HazMat fee they're ludicrous. And as I look at these MPR kits in the Estes catalog, they don't go any higher or faster than LPR kits. (MPR really does not interest me) Wouldn't clustering Cs do the same thing?

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Your definition of LPR vs. MPR is a bit inconsistent.
It probably does not help that MPR label is not uniformly defined.

To most, MPR starts with 29mm motors. Those could be as mild as E16's, and go into G's, and even H's and I's.
Many of these (E, F, and even G's) RMS reloads can be shipped without HazMat charges. Others incur HazMat, all subject to USPS propellant grain weight rules. So it's not as simple as you state above.

H+ motors are commonly designated as HP.
Yes, one can find G-motors to stuff into a 24mm tubes, and you can label that whatever power level you want.
Frankly, the label does not matter.

BrainlordMesomorph said:

So I'm going start dabbling in multistage w/ a simple LPR 2 stager. but later I want to add a 3rd booster and that should be MPR or clustered LPR (or... what?)

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Sounds good - have fun in all of the above ways!
There is no single right solution, just a common realization that once you start going high enough, often enough, you will be loosing rockets without GPS trackers.
Once you start adding GPS trackers, the extra weight will push you into another power + weight category, which most folks will call MPR. And you can have a LOT of fun there, without ever paying HazMat fees!

a

BrainlordMesomorph said:

The goal of my rocketry program has always been higher and faster.)

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I may be wrong, bit if your goal is higher, for MODEL Rocketry I am not sure staging is the best way to accomplish your goal.

Because MODEL rockets are fin stabilized, every time you add a stage you add more tail weight and need more fin surface area. Becomes a losing battle, particularly as you go from one booster to two or more. SPACE rockets like Saturn V have gimballed engines for guidance, so adding stages DOES make sense to drop you mass with each stage as you ascend.

Don’t get me wrong, staging is cool, but not necessarily the best method to get higher

Recovering your boosters also gets more challenging, particularly if you go with simple black powder staging with tumble recovery. SINGLE booster not too bad, as usually will stage/ignite upper stage below around 200 feet, so booster comes off hopefully within visual range to track it to ground. If you have TWO booster sections, likE Comanche, your second booster is up there pretty high, particularly if you have the original 24/18/18 version and you go D12-0 to C6-0 , the upper booster is gonna be waaaaaaaay up there at separation and with no chute or streamer is gonna be really hard to see(put whatever you want in sustainer, but with above load on boosters, hope for windless day and big field if you don’t have a tracker in it, and I am not sure one will fit.)

There are ways with black powder staging to add a streamer or chute to boosters, but they add complexity, decrease reliability, and more pertinent to your goal of higher , add mass to the back end of your rocket, altering CG which requires either more nose weight or bigger fins ——- either/both will DECREASE your achievable max altitude.

If max VELOCITY is your goal, staging MAY make sense, as, given the same rocket with same motor flying as single stage off the pad vs flying as a sustainer on top of a booster, the two stage version sustainer I THINK would reach a higher maximum velocity as it already has velocity when it ignites off the booster, so it doesn’t waste impulse just getting off the pad. Hopefully you won’t shred your fins!

Summary: at first glance and logically you would expect better ALTITUDE with multistage rockets, but practically with MODEL rockets you can do as well or better with a single stage design and a larger motor. At least gram for gram propellant-wise. Max velocity should be higher for multistage.

afadeev said:

H+ motors are commonly designated as HP.
Yes, one can find G-motors to stuff into a 24mm tubes, and you can label that whatever power level you want.
Frankly, the label does not matter.

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Be careful here, any motor with >80N average thrust is a high power motor in the US, also if it has more than 62.5 grams of propellant. All of CTI's 24mm G motors are either above one or both of those qualifications (The longburn G64 has 80 grams of propellant). Remember the propellant mass also makes these rockets require a waiver to fly.

Also all rocket motors are Hazmat shipping, BUT you can ship motors with individually packaged grains of no more than 30 grams via USPS ground for no additional charge. Everything else has to be sent UPS or FedEx and they slap a ~$30 dollar charge to ship them. https://www.nar.org/wp-content/uploads/2014/05/Shipping-Rocket-Motors.pdf

<125g, <80N, non-sparky.

The issue is, mid power doesn't actually exist legally. So I wouldn't worry about defining it.

If you wanna go fast and high, get into G reloads in the aerotech 29/40-120 case. Many non-hazmat reloads, and the costs are not too crazy. A G76G will easily lift 3.3 pounds... so, play with those numbers in your head.

neil_w said:

BP E and F engines do incur hazmat charges

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buy them from Hobby Lobby. 40% off and no Hazmat

solid_fuel said:

buy them from Hobby Lobby. 40% off and no Hazmat

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Unfortunately they stopped carrying F15-0, which is the one I most want.

Thanks guys this has been very informative.

I thought 24mm meant D meant mid power meant hazmat fees. (I thought LPR stops at C) Now I see its not like that.

I was disappointed that I topped out C class rockets so quickly. But that was just because I had my head buried in the Estes sand.

With 18mm Ds and non-hazmat 24mm Es the speeds and altitudes I was hoping for are going to be within reach (without having to learn to weld) Now I have a good several years of rocketry experimentation ahead of me.

As for clustering:
If that D21 weighs the same as a C6, then that c6 must have a abysmal thrust to weight ratio. and clustering low TWR engines is adding more weight than thrust. Now a pair of those D21s on the other hand....

BrainlordMesomorph said:

If that D21 weighs the same as a C6, then that c6 must have a abysmal thrust to weight ratio. and clustering low TWR engines is adding more weight than thrust. Now a pair of those D21s on the other hand....

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Certainly APCP has much higher thrust to weight than BP. IMHO clustering BP is more for fun than for performance (speaking of which, haven't seen anything new from Boris Katan lately... BrainlordMesomorph: go check out this thread if you haven't already seen it, and/or search Boris Katan on Youtube).

BrainlordMesomorph said:

With 18mm Ds and non-hazmat 24mm Es the speeds and altitudes I was hoping for are going to be within reach (without having to learn to weld) Now I have a good several years of rocketry experimentation ahead of me.

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one thing with the 18mm D motors if ya plan to stage to them: they cant stage like the BP motors. gonna require electronics to light em.

tomsteve said:

one thing with the 18mm D motors if ya plan to stage to them: they cant stage like the BP motors. gonna require electronics to light em.

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Good to know.

I'm going to be hip deep in the electronics once I have rockets that can lift them.

Hey, look at this

https://www.questaerospace.com/2-Pack_D16-8_Q-Jet_Model_Rocket_Motor/p4193205_18980177.aspx

Via shreadvector posting in the Q-jet thread

jlabrasca said:

Hey, look at this

https://www.questaerospace.com/2-Pack_D16-8_Q-Jet_Model_Rocket_Motor/p4193205_18980177.aspx

Via shreadvector posting in the Q-jet thread

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Those are cool.

(The reason professional hand models exist:
)

EDIT: (after reading more about them) OH I SEE, those are very cool.

Brainlord Mesomorph said:

Thanks guys this has been very informative.

I thought 24mm meant D meant mid power meant hazmat fees. (I thought LPR stops at C) Now I see its not like that.

I was disappointed that I topped out C class rockets so quickly. But that was just because I had my head buried in the Estes sand.

With 18mm Ds and non-hazmat 24mm Es the speeds and altitudes I was hoping for are going to be within reach (without having to learn to weld) Now I have a good several years of rocketry experimentation ahead of me.

As for clustering:
If that D21 weighs the same as a C6, then that c6 must have a abysmal thrust to weight ratio. and clustering low TWR engines is adding more weight than thrust. Now a pair of those D21s on the other hand....

Click to expand...

The FAA used to have different rules for rockets that weighed up to a pound in flight ready configuration (model rockets), above a pound and up to 3.3 lbs. (high power model rockets), and above 3.3 lbs. Impulse levels were also conditions.
Now they’ve divided it into Class 1 (model rockets up to 1500 grams and specific impulse requirements - no waiver needed), Class 2 (above 1500 grams with total impulse up to 40,960 Newton seconds), and Class 3 (above 40,960 Ns).
Class 2 rockets can be flown under an event waiver, but Class 3 rockets typically require a certificate of authorization per rocket.

Ok here's a design:
That's a basic design of a three stager that (according to OR) will carry 20g to 40g to 4000 ft and/or break the speed of sound, depending on various motor configurations and payloads.

I love that fact that the stages are interchangeable, so that just a 19mm booster and a 24mm booster. But if you use a D12 (or that F44 ) then stage 2 is falling from 400 ft and its going to need a recovery system. Which means electronics to light stage 3.

I'm not there yet, but I can build this and start flying it with Bs and Cs.
And then get there.

Thoughts?