Multi-Stage Rocket Help

So, You may have already seen this video of my 4' tall 3in dia model rocket launch...

However, I recently been processing ways to get this thing higher. (Not to "high altitude", just at least 3x higher than befor (It reached 1300ft))
[video=youtube;AKCJOxggPLc]https://www.youtube.com/watch?v=AKCJOxggPLc[/video]
I used two F engines placed side by side inside the body tube. Rather than increasing the number of engines or size, I've been processing
setting them in multistage. (two boosters below with two cruise engine above) I sort of new to this, any suggestions to the best ways to do this? Do the booster stages have to fall out after ignition of the second stage? Also, with all that flame of the second stage buried up inside the body tube, don't i risk it catching fire? thanks!

--Grant Wise

To send it higher, you of course need more total impulse - from either more motors (staged or clustered) or more powerful motors (or both.)
Note: going above 125g of total propellant would put you in high power, level 1 certification territory so watch those numbers.
Among the options would be to:
A. change the motor scheme to a cluster of four composite F motors
B. change the motor scheme to use two composite G motors
C. build a booster stage and use the current rocket as the sustainer, two composite F's in the booster and two composite
F's in the sustainer.
D. stacking two composite F's (I think that was what you were asking about)

I would recommend against option D.
To keep the propellant weight down at higher total impulse, you will need to use composite motors.
It may be difficult to get both motors of the sustainer stage to light.
It seems easiest to use two G composites.

Good luck with whatever route you choose!

Do you want to get 'this' rocket higher, or 'a' rocket higher. jjhdnd is right for 'this' rocket. A 3" tube with those huge fins means a lot of drag. For 'a'nother rocket, I would recommend a minimum diameter 29mm, 3 minimum size fins for 1 caliber of stability. Then stuff a max G long burn motor in it.

I used two F engines placed side by side inside the body tube.

Click to expand...

That was for 1300'. My Big Bertha with a minicam and altimeter reached over 1400' with one E9. Don't over complicate things when you don't have to. Just more things to go wrong. Murphy never sleeps.
That bird looks good.

Not sure how new you are to all this, so here are some definitions:

Clustering - multiple motors that fire all at the same time in a single airframe stage

Staging - multiple motors that fire sequentially in multiple airframe stages

Staging can be done with black powder motors by letting the burnout of the first stage motor ignite the second stage motor, and so on. But with AP composite motors, this doesn't work. So one can use a flight computer (altimeter, etc.) to do an "air start." In this case, the flight computer ignites the second motor while it is traveling through the air.

I want to elaborate on what "jjhdnd" wrote.

If you are unaware, the BATFE (Bureau of Alcohol, Tobacco, Firearms, and Explosives) regulates use of explosives in rocket motors, as well as the FAA anything that flies in the air, and there are legal guidelines as to who can fly rockets based on their expected altitude and the amount of explosive in the motor(s).

Please see the NAR or TRA guidelines for High Power Rockets (HPR). If you cluster motors, you may be flying a HPR, even though the individual motors are not HPR motors. If you cluster two G motors, for instance, you may have drifted into H total impulse. This is illegal unless you are HPR certified by NAR or TRA.

As for altitude, the FAA controls the airspace, and they have regulations as well. Rockets traveling exceptionally high require an FAA waiver. This is a permission granted by the FAA for a particular date, location, and altitude. The FAA then informs airports of the waiver, to ensure that planes fly above the waiver or avoid the area.

I don't recall offhand what the lowest altitude requiring a waiver is, so find out.

To answer your question about staging--yes, the booster must fall away when the second stage ignites; otherwise you end up with a fire.

If you want to get a gopro camera to 3K, you're probably gonna have to look at HPR as an option. I'm not sure what diameter you need, but I'd guess 2.5 at least. to put a 2.5" rocket with a 3-4oz camera in it, You're going to need a decent sized motor. A quick and dirty sim of a 2" diameter weighing 15oz with the camera in it needs an H180W to put it to 3k. 2 G64Ws will do it in a 13oz, 2.5" rocket, but only just.

Nate

jjhdnd said:

Among the options would be to:
A. change the motor scheme to a cluster of four composite F motors
B. change the motor scheme to use two composite G motors
C. build a booster stage and use the current rocket as the sustainer, two composite F's in the booster and two composite
F's in the sustainer.
D. stacking two composite F's (I think that was what you were asking about)

I would recommend against option D.
To keep the propellant weight down at higher total impulse, you will need to use composite motors.
It may be difficult to get both motors of the sustainer stage to light.
It seems easiest to use two G composites.

Click to expand...

Thanks!
It does seem that going with two composite G's would be my best route, and a whole lot easier than trying to set up a staged ignition.

Bat-mite said:

Please see the NAR or TRA guidelines for High Power Rockets (HPR). If you cluster motors, you may be flying a HPR, even though the individual motors are not HPR motors. If you cluster two G motors, for instance, you may have drifted into H total impulse. This is illegal unless you are HPR certified by NAR or TRA.

Click to expand...

Any idea how hard it is to get one of these? Is it even possible for someone under 18?

Bat-mite said:

To answer your question about staging--yes, the booster must fall away when the second stage ignites; otherwise you end up with a fire.

Click to expand...

Do you know of any sources that go further in-depth as to how this is done?

Thanks!

mikemech said:

Do you want to get 'this' rocket higher, or 'a' rocket higher. jjhdnd is right for 'this' rocket. A 3" tube with those huge fins means a lot of drag. For 'a'nother rocket, I would recommend a minimum diameter 29mm, 3 minimum size fins for 1 caliber of stability. Then stuff a max G long burn motor in it.

Click to expand...

Specifically "this" rocket. So even if I rebuilt it, a 29mm tube would not be large enough to cary my GoPro. Also, based on my rocket size do you think my fins are to big? I have read about CP and CG, and used rocketsim to make sure it flew properly, but I had know way of knowing just how small I could get them before i start sacrificing stability for drag.

Thanks!

mikemech said:

That bird looks good.

Click to expand...

Here are all the NAR and TRA HPR rules. There is a junior program for HPR under 18, but there are additional requirements and restrictions.

Here are two excellent articles on staging by Tim van Milligan of Apogee Components. One Two

It might behoove you to buy a small, two-stage kit like an Estes Hyper-Bat or a Fliskits Cheetah! to get familiar with the concepts. Then apply what you learn to your bigger rocket.

Bat-mite said:

Here are all the NAR and TRA HPR rules. There is a junior program for HPR under 18, but there are additional requirements and restrictions.

Here are two excellent articles on staging by Tim van Milligan of Apogee Components. One Two

It might behoove you to buy a small, two-stage kit like an Estes Hyper-Bat or a Fliskits Cheetah! to get familiar with the concepts. Then apply what you learn to your bigger rocket.

Click to expand...

Thanks! I will look into that.

Mission parameters:
4000 feet altitude
3" dia camera payload
Camera weight?

In RockSim open your rocket file. Go to 'Save As' and name the file '(rocket) a'. You now have two files with the same rocket. Leave the '(rocket)' file alone and make changes to the '(rocket)a' file.
In the '(rocket)a' file, highlight the aft airframe tube and click 'subassembly'. Move all your motor mount parts into this subassembly. Save.
You can make different motor mounts for the rocket this way and switch them around until you get the sim results you want.
Make a '(rocket)fin' file. This will be for fin modifications.
Delete the fins. Highlight the aft airframe tube and click 'Fins'. Load the heaviest motor(s) you think that you will use. Look at the stability margin. Must be between 1 and 2. If it is below 1, you need more fin area. Above 2, less fin area. Play with the fin dimensions until the stability margin is OK.

Re-reading this, it sounds like I'm giving detailed instructions to a moron. I don't mean it that way. Seeing you rocket shows that you are not stupid. Reading your text shows that you are inexperienced.

See tech reports here: https://www.spacemodeling.org/JimZ/index.htm
Read the "Handbook of Model Rocketry" by Stine, and "Model Rocket Design and Construction" by Van Milligan.

mikemech said:

Mission parameters:
4000 feet altitude
3" dia camera payload
Camera weight?

In RockSim open your rocket file. Go to 'Save As' and name the file '(rocket) a'. You now have two files with the same rocket. Leave the '(rocket)' file alone and make changes to the '(rocket)a' file.
In the '(rocket)a' file, highlight the aft airframe tube and click 'subassembly'. Move all your motor mount parts into this subassembly. Save.
You can make different motor mounts for the rocket this way and switch them around until you get the sim results you want.
Make a '(rocket)fin' file. This will be for fin modifications.
Delete the fins. Highlight the aft airframe tube and click 'Fins'. Load the heaviest motor(s) you think that you will use. Look at the stability margin. Must be between 1 and 2. If it is below 1, you need more fin area. Above 2, less fin area. Play with the fin dimensions until the stability margin is OK.

Re-reading this, it sounds like I'm giving detailed instructions to a moron. I don't mean it that way. Seeing you rocket shows that you are not stupid. Reading your text shows that you are inexperienced.

See tech reports here: https://www.spacemodeling.org/JimZ/index.htm
Read the "Handbook of Model Rocketry" by Stine, and "Model Rocket Design and Construction" by Van Milligan.

Click to expand...

Thanks. I am inexperienced. Even though I love physics and engineering and have been building things for years, this was only my third homemade rocket.
and I am still picking up some new terms and concepts.

Anyone stage a composite to a BP motor using the composites ejection to start the BP motor?

crazyed said:

Anyone stage a composite to a BP motor using the composites ejection to start the BP motor?

Click to expand...

It has been done, but more likely than not you won't get an upper stage ignition as the ejection charges are pretty powerful and likely to separate the stages but not ignite. Also you have to worry about the rocket staying upright during the coast phase so you don't get a staging event horizontally or worse, pointing down. A staging timer would take care of that.

The original rocket used a cluster of BP F motors. There are BP F motor boosters out there. I don't know if they have the oomph to get this particular rocket off the ground safely. Plus you run into the propellant weight limit- F15 has 60g each, 4x60= 240 which puts you into HPR territory

Grant asked about a resource for going more into staging- Handbook of Model Rocketry
has this and you might even find a copy at your library.

kj

kjohnson said:

Grant asked about a resource for going more into staging- Handbook of Model Rocketry
has this and you might even find a copy at your library.

kj

Click to expand...

Thanks! I'll check it out.

So.... The only way I can become HPR certified is by first becoming a NAR member and then.......

NAR membership costs $$$$. This seems stupid that for me to become "legal" I have to pay an organization $$. Is it even a government organization?
Can I get certified without going through NAR?

Thanks!

The government organizations that regulate rocketry would, in all honesty, prefer that rocketry go away. The NFPA and FAA have strict guidelines as to what is legal or not legal.

NAR and TRA are non-profit organizations that promote rocketry. As such, they grant memberships and collect dues. They ensure that NFPA and FAA guidelines are met so that people are not breaking rocketry laws and rocketry does not become outlawed.

Almost everyone who posts to these forums is a member of NAR or TRA or both.

No one is requiring you to join a club or to fly high power. If you want the thrill of launching a rocket with a HPR motor or clustered motors that cross into HPR territory, then that is how you do it. Like paying for a movie ticket when you could stay home and watch TV. Is it worth it to you? Your choice.

But if you launch a rocket that falls into regulated territory without being certified, you can go to jail.

crazyed said:

Anyone stage a composite to a BP motor using the composites ejection to start the BP motor?

Click to expand...

Yes, with some modifications. https://forums.rocketshoppe.com/showthread.php?t=12147

Bat-mite said:

The government organizations that regulate rocketry would, in all honesty, prefer that rocketry go away. The NFPA and FAA have strict guidelines as to what is legal or not legal.

NAR and TRA are non-profit organizations that promote rocketry. As such, they grant memberships and collect dues. They ensure that NFPA and FAA guidelines are met so that people are not breaking rocketry laws and rocketry does not become outlawed.

Almost everyone who posts to these forums is a member of NAR or TRA or both.

No one is requiring you to join a club or to fly high power. If you want the thrill of launching a rocket with a HPR motor or clustered motors that cross into HPR territory, then that is how you do it. Like paying for a movie ticket when you could stay home and watch TV. Is it worth it to you? Your choice.

But if you launch a rocket that falls into regulated territory without being certified, you can go to jail.

Click to expand...

So if my HPR rocket does not encroach upon FAA airspace and It lands safely on my property, I don't "technically" have to be certified?

Grant,

First off welcome to the forum. You've covered an awful lot of ground in this thread and I'll try not to re-hash it all. I think there is alot you can do with rockets before getting into high power and certification issues. Take a look at the Handbook and some of the other resources mentioned. I might be inclined to hit up the Science Department at school to see what their knowledge base is. Better yet attend a club launch if you can to see the rockets and talk to the local experts.
The certification process was developed by the two national hobby rocket organizations (NAR and Tripoli) and the insurance industry to promote the safe growth of the hobby and to give local jurisdictions a framework to separate the hobby from other pyrotechnic activities like fireworks displays. Now to address a practical matter I can't think of any vendor who would sell high power motors to anyone who didn't have proof of certification so there's that. But, really, I think that's getting ahead of your present situation.

Take a look at these two sites to find a club and a high power launch near you and go learn and have some fun, and don't worry about jail time. :wink:

https://www.nar.org/find-a-local-club/nar-club-locator/

https://www.tripoli.org/Membership/PrefecturesClubs/USAPrefectures/tabid/257/Default.aspx


{edit} Sorry, the answer to your question is "No, you don't". My advice is NOT to go down that road. Good luck and stay safe.

grwise1 said:

So if my HPR rocket does not encroach upon FAA airspace and It lands safely on my property, I don't "technically" have to be certified?

Click to expand...

If you are flying on your own property or on the property of others with the permission of the landowner, you do not need to be a member of either the NAR or TRA organizations. However, you will not have the benefit of liability insurance and you will be obligated to all the local, state and federal laws that apply. The FAA is primarily concerned with hazards to aircraft while your state and/or local fire marshal will be concerned about wildfires. Your neighbors may complain should you do something really stupid.

Here https://www.ecfr.gov/cgi-bin/text-idx?rgn=div5&node=14:2.0.1.3.15 are the current FAA regulations regarding Amateur Rockets.

You say your Go-Pro rocket went to 1,300 feet on two F motors. Would those motors have been Estes F-15 black powder motors? Looking at your YouTube videos that would appear to be the case. I also note that you are a minor and assume your parents must buy the motors you are using. This presents a problem for you until your are 18 and all of these motors call for "adult supervision" when used by minors. It sucks, but hey, it is what it is. All that being said, I think your best bet would be to build a stronger air frame with a single 29 mm motor mount for a G size Aerotech motor and a payload bay up front to house your Go-Pro camera. I have a scratch built rocket that I made from a two inch I.D. mailing tube that has a total lift off weight with motor of about 19 ounces (1.25 lbs) It will easily exceed 3,000 feet and you could expect similar results with a similar design. If the camera is toward the front it will help you with your CG/CP stability requirements.

I am very impressed with your progress as a rocket maker and flyer. And it looks like you guys were having a blast with your rockets. Have fun, use common sense and be safe!

Okay.

Thanks.

tmacklin said:

You say your Go-Pro rocket went to 1,300 feet on two F motors. Would those motors have been Estes F-15 black powder motors?

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Yes

grwise1 said:

Yes

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I read further in your links and see that now.

I don't have a Go-Pro camera but now you've forced me to buy one! That is a great video and a great flying rocket, despite the deployment failure. Keep up the good work and please, post more videos!

tmacklin said:

I read further in your links and see that now.

I don't have a Go-Pro camera but now you've forced me to buy one! That is a great video and a great flying rocket, despite the deployment failure. Keep up the good work and please, post more videos!

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Thankyou! I hope to continue more vids. I should mention that photography is another one of my hobbies. You can also subscribe to my YouTube channel to get the lates videos that I post. YoutTube/GrantWise

grwise1 said:

Thankyou! I hope to continue more vids. I should mention that photography is another one of my hobbies. You can also subscribe to my YouTube channel to get the lates videos that I post. YoutTube/GrantWise

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Will do, Grant!

There were a couple of comments on the difficulty of igniting upper series staged motors. Be sure to check out parallel staging (strap on boosters).

mikemech said:

There were a couple of comments on the difficulty of igniting upper series staged motors. Be sure to check out parallel staging (strap on boosters).

Click to expand...

Alright. I will. Although I plan to build some multi-stage rockets in the future, I will probably end up just increasing my GoPro rocket's engine size to a G...

Thanks for all the comments!

Lots going on in here, I'll touch on what caught my eye.

Under 18, the best option is single use G motors. You'll run into hazmat shipping for those, so order many at once to make the sting less. (unless you can get in on an order with other local fliers)
If you have an adult load and fly reloadable motors are a cheaper and non hazmat option. (those are the rules, which are what I'm able to tell you to do)

Single use G's (aerotech G77,G78,G79, and G80) all can be flown in a double cluster without breeching into HP.
Reloadables for the 29/40-120 (G53,G64, G76) and for the 29/120 (G25, G77,G79) can be flown in pairs without going into HP.

This graph combines FAA/NFPA/TRA/NAR rules/laws
https://www.doug79.com/stuff/HPR_metric9c.pdf

As far as I know, all airspace is FAA controlled. (could be wrong, but this is one I don't want to run afoul of)

TRA and NAR are organizations that provide many benefits. Insurance, information, and a great resource for clubs. If you're not venturing past a pair of single use G's or launching with a club, it may not be for you. If you're going to cross over into HPR it makes a ton of sense. Not to mention they fought a nearly ten year legal battle with the ATF and won. Without that we'd be paying the government a hell of a lot more to be able to fly anything....and jumping through even more hoops.

Grant,

Nice flight and video. I am particularly interested in your recovery rig. Most rockets "dangle" on a single shock cord and bounce around like crazy on descent. Your descent video was really smooth, perhaps even better than the ascent portion. Did you have a single shock cord or any other special attachment of rocket to chute?

BTW, NAR membership for under age 21 is 25 bucks a year. https://www.nar.org/wp-content/uploads/2014/05/membership.pdf
It comes with 2 million dollars of liability insurance (which certainly might make your PARENTS willing to ante up!) and provides a pathway to legal HPR. Overall annual cost is about the same as one three F motor launch. I think it is a pretty good (and smart) deal for you.

Looking forward to more posts and videos from you.

Tom