An "R"-powered rocket build

[Paulb06]

I’ve been told you can drill holes into the metal router table and insert a metal pin first for the outer cut then one for the inner cut?

Would this not work?

Chuck C.

Yes but you need to be able to adjust the distance...its unlikely you'll hit it perfectly the first time....the router mount will probably have some adjustment in it, so that may work....cutting the inside hole is trickier, when you finish the cut, hold the ring still and shut the router off

 

[Rail Dawg]

Yes but you need to be able to adjust the distance...its unlikely you'll hit it perfectly the first time....the router mount will probably have some adjustment in it, so that may work....cutting the inside hole is trickier, when you finish the cut, hold the ring still and shut the router off

Got it. Fortunately most of the CR’s don’t have to be perfect on the ID.

They are for the stringers and strength of the airframe.

Just the very bottom and very top of the lower stack needs to be right on to center the motor.

Thanks for the info.

Chuck C.

 

[TonyL]

Trying to get 12" custom centering rings is not an easy task. Most rocketry stores say sure but they can't guarantee the size will be exactly what I ordered.

Chuck, ultimately it is just a centering ring, not the injector plate for an Apollo mission

A circle cutter attachment for a router [plus a router] and a 1/4 sheet of plywood and a ruler is all you actually 'need'. If one is patient enough, a hand saw and sandpaper would work but it takes longer. I have used the circle attachment many times for large centering rings that are dead on each time once the fixture is adjusted.

Getting a store to commit to a tight dimensional tolerance is asking a lot unless you tell them they can charge you for the scrap too, and even then they probably won't be happy about that. If you really want it CNC cut, then a serious cabinet shop would have a CNC router that does what you want, but you will have to pay for their time & overhead. Using the fixture you can theoretically hit a tighter tolerance and precision than the CNC cutter.

br/
Tony

 

[Rail Dawg]

Chuck, ultimately it is just a centering ring, not the injector plate for an Apollo mission

A circle cutter attachment for a router [plus a router] and a 1/4 sheet of plywood and a ruler is all you actually 'need'. If one is patient enough, a hand saw and sandpaper would work but it takes longer. I have used the circle attachment many times for large centering rings that are dead on each time once the fixture is adjusted.

Getting a store to commit to a tight dimensional tolerance is asking a lot unless you tell them they can charge you for the scrap too, and even then they probably won't be happy about that. If you really want it CNC cut, then a serious cabinet shop would have a CNC router that does what you want, but you will have to pay for their time & overhead. Using the fixture you can theoretically hit a tighter tolerance and precision than the CNC cutter.

br/
Tony

Ah words of wisdom! So true!

The main motor CR’s (5-6 at most and those are stacked at 2-3 each) need to be right on but the rest... no big deal.

Thanks!

Chuck C.

 

[TonyL]

Chuck,

So technically you only need one motor centering ring to be precise in each stack, one in the top and one in the bottom. The rest are just reinforcing the precise ring. The top motor centering ring usually does not need to be very thick if you are transferring thrust through the bottom ring, and neither would need to be very thick if you are transferring thrust at the head end. Keeping weight out of the tail end is very desirable for most rockets.

br/

Tony

 

[Rail Dawg]

Chuck,

So technically you only need one motor centering ring to be precise in each stack, one in the top and one in the bottom. The rest are just reinforcing the precise ring. The top motor centering ring usually does not need to be very thick if you are transferring thrust through the bottom ring, and neither would need to be very thick if you are transferring thrust at the head end. Keeping weight out of the tail end is very desirable for most rockets.

br/

Tony

The loaded motor is 300 lbs so am going a little overboard.

In fact the whole rocket is being built strong. Other forces are deployment. Should the main anchor point fail (the motor upper enclosure eye-bolt) the upper centering rings and upper thrust plate will be the back-up.

This rocket actually is over-stable due to the length and weight of the motor.

Keep the suggestions coming Tony.

Chuck C.

 

[Wallace]

Ah words of wisdom! So true!

The main motor CR’s (5-6 at most and those are stacked at 2-3 each) need to be right on but the rest... no big deal.

Thanks!

Chuck C.

There's your answer; plenty of practice rings to make for starters, by the time you get those finished you'll be an old hand that'll be able to make perfect motor rings. Practice after all does make perfect...

 

[HASTE]

Outside the square thought, do they have to be centering rings for the motor case ?
Could they be 4 rods or similar spaced at 90 degrees laying length ways inside the body to support the case to do the same task ?

 

[HASTE]

double post

 

[Rail Dawg]

The CR’s on the top and bottom of the motor will be a perfect fit through sanding.

The others in between can be slightly larger to ensure the motor will slide up the almost 10 ft length.

I think it’s going to work well.

Chuck C.

 

[EeebeeE]

I tdon'k know about the outer diameter of your CR, but Dremel makes an excellent circle cutter for your motor tube hole.

 

[Rail Dawg]

Thanks for that Evan.

I've been following your 100,000 ft thread.

Good stuff.

Chuck C.

 

[Ez2cDave]

Fortunately most of the CR’s don’t have to be perfect on the ID.

Chuck C.

AHEM ! This ain't no Estes "Mosquito", Chuck . . . LOL !

Recovery is still the primary concern, "from my chair" . . . Getting RELIABLE ejection, above 40,000 ft. AGL is "Job #1".

If that fails to occur, the rest of the Recovery System means nothing, with a streamlining rocket . . . I do not want to "put Sir Isaac Newton in the Driver's Seat" !

Adapt & Overcome . . . Failure is not an option !

Dave F.

 

[davdue]

Next years BALLS is the plan!

Would like to learn more about building a large nosecone if I go bigger than 12”.

Any custom builders of these out there?

Chuck

I think this should fly at LDRS 38. I may have missed it as I have read most of this thread, but what is the expected altitude?

 

[Rail Dawg]

I tdon'k know about the outer diameter of your CR, but Dremel makes an excellent circle cutter for your motor tube hole.

AHEM ! This ain't no Estes "Mosquito", Chuck . . . LOL !

Recovery is still the primary concern, "from my chair" . . . Getting RELIABLE ejection, above 40,000 ft. AGL is "Job #1".

If that fails to occur, the rest of the Recovery System means nothing, with a streamlining rocket . . . I do not want to "put Sir Isaac Newton in the Driver's Seat" !

Adapt & Overcome . . . Failure is not an option !

Dave F.

I have to defer to an old rocketeer friend Jim Jarvis and his good work in BP-at-altitude techniques:

https://www.rocketryfiles.com/files/Technicalarticles/Jim_Jarvis_Highaltitude_deployment_2013.pdf

Take a look at the "postscript" at the bottom of his article.

Bottom line is we are going to design redundant metal "cannons" with 2 igniters each, the right amount of BP and plenty of air trapped in the cannon so the BP has enough air for the heat transfer.

Looking at surplus military T10D chutes that have been replaced by the T11. With the correct packing in a deployment bag and using the techniques the military uses we're pretty confident of recovery success.

Need to do a drop-test with a 350-lb sandbag off a tall bridge to test the whole thing out. Well that would be if we could do it with the right permissions lol.

Appreciate your keeping us on our toes Dave. Don't stop with the ideas and suggestions.

Chuck C.

 

[Rail Dawg]

I think this should fly at LDRS 38. I may have missed it as I have read most of this thread, but what is the expected altitude?

Hi Dave the expected altitude is 38,000 - 40,000 ft. It's not being built to set records but to be as safe/strong as possible.

It will weigh about 575 lbs loaded.

The KloudBusters sponsoring LDRS 38 are rightfully concerned about the safety of all spectators. Perhaps as we go through the Tripoli C3RC (Class 3 Review Committee) procedures we might get an invite to LDRS 38.

But this is really a BALLS rocket.

Next year will be an R to R staging so hang onto your hats!

Chuck C.

 

[Rail Dawg]

OK I'm cooking with gas now!

Got the router table all set up. Table saw all warmed up and belt sander ready to belt out some CR's and stringers.

Just got the rock-solid specs for the OD and ID of the 11.67" airframe and couplers along with the motor casing OD.

Got to practice some but I suspect shortly you'll all see CR's and stringers flying out of the rocket shed like it's nobody's bidness lol.

PS: My hot-blooded Latin woman is starting to look at me sideways with all the boxes being carried into the rocket shed. Must tread carefully!

Chuck C.

 

[Ez2cDave]

Hi Dave the expected altitude is 38,000 - 40,000 ft. It's not being built to set records but to be as safe/strong as possible.

It will weigh about 575 lbs loaded.

Chuck C.

Chuck,

We won't know, for sure, until actual static motor testing has been done and we have accurate "numbers" for both the empty and "all up" weight.

FWIW - An all Cast Iron ( Block, Heads, & Intake ), Chevrolet Small-Block 350 V-8, from the early 1970's, weighed 575 lb, without all the brackets and accessories hooked up.

Dave F.

 

[Ez2cDave]

Next year will be an R to R staging so hang onto your hats!

Chuck C.

Chuck,

Velocities in excess of Mach 4 will likely be encountered on that project . . .

Dave F.

 

[Ez2cDave]

Need to do a drop-test with a 350-lb sandbag off a tall bridge to test the whole thing out. Well that would be if we could do it with the right permissions lol.

Appreciate your keeping us on our toes Dave. Don't stop with the ideas and suggestions.

Chuck C.

Chuck,

I have an idea for the Drop Test . . .

Contact a local Skydiving Club and have them do the test from a higher altitude. They typically "bail out" at 12,500 ft. AGL.

Use a timer or an altimeter to trigger it and set the deployment for the same altitude you want for the Main Chute to deploy.

That way, you get a "real world" test of the system, at altitude. Attach your Drogue to it and you get an "all up" test of the recovery system !

Shoot video of the test for later analysis and evaluation.

Dave F.

 

[Rail Dawg]

Chuck,

I have an idea for the Drop Test . . .

Contact a local Skydiving Club and have them do the test from a higher altitude. They typically "bail out" at 12,500 ft. AGL.

Use a timer or an altimeter to trigger it and set the deployment for the same altitude you want for the Main Chute to deploy.

That way, you get a "real world" test of the system, at altitude. Attach your Drogue to it and you get an "all up" test of the recovery system !

Shoot video of the test for later analysis and evaluation.

Dave F.

Not a bad idea at all. Those guys would dig it.

Chuck C.

 

[Ez2cDave]

Chuck,

The only "caveat" is that either you or another Member of the "Prime Team" would need to be on board the plane ( not necessarily jumping ) to safely arm the electronics and oversee the deployment from the aircraft.

If using an Altimeter, things like "do not arm the electronics until the Cabin Door is open" come to mind ( pressure change might fire the deployment charge / charges ).

With a Timer ( possibly using a "pull-pin" ), the main concern is to make sure all electronics are dead AND the ""ACTIVATION PIN" is SECURELY in place until just prior to actual deployment.

I strongly suggest the above measures, on many levels ( more may be needed ).

If it is determined to be "safe enough" by you and the rest of the Prime Team ( not in my "job description" ). "Go-Pro"-wearing skydivers could, at a safe distance, free-fall along with the "package", possibly until deployment, altitude permitting ! If so, a free-falling skydiver descends at a rate of 175 - 250 ft/sec ( 53 - 76 m/sec ). I am NOT a skydiver, so ask the experts !

https://skydiveparacletexp.com/2016/11/10/how-fast-do-skydivers-fall

https://www.chattanoogaskydivingcom...es/how-fast-do-skydivers-fall-through-the-air

https://www.quora.com/If-a-skydiver-is-falling-how-long-would-it-take-to-reach-terminal-velocity

A handy calculator, if a TIMER is used :

https://www.angio.net/personal/climb/speed.html

Dave F.

 

[TonyL]

Chuck,
a word of advice from past experience: be careful about making your centering rings too 'perfect'. Stuff changes size with temperature. 11.67 inches is not all that precise in the realm of metal tubing, more so for cardboard [phenolic, fiberglass, whatever], but even cardboard will match the mandrel better than that. Having a piece of airframe to fit the rings to is extremely desirable. Having your motor guy tell you how oval the motor case is would be good to know. filament wound tube often has a very slight taper to the ID.

Also blue tape [or kapton if you want to use what rocket scientists use] makes a fine shim, much better than being out at the launch site with the motor jammed halfway into the rocket because something does not fit like it did at home.

I would cut the hole between 1/32" and 3/64" oversize as a starting point against the max diameter of the case if you don't have it available to fit the rings to it. The OD can be a closer fit to the airframe as one wants a 0.005" to 0.020" thick bond thickness [0.005" preferred] for typical epoxy. The thinner the gap, the easier the ring is to cock in the tube and jam.

br/

Tony

 

[Rail Dawg]

Chuck,
a word of advice from past experience: be careful about making your centering rings too 'perfect'. Stuff changes size with temperature. 11.67 inches is not all that precise in the realm of metal tubing, more so for cardboard [phenolic, fiberglass, whatever], but even cardboard will match the mandrel better than that. Having a piece of airframe to fit the rings to is extremely desirable. Having your motor guy tell you how oval the motor case is would be good to know. filament wound tube often has a very slight taper to the ID.

Also blue tape [or kapton if you want to use what rocket scientists use] makes a fine shim, much better than being out at the launch site with the motor jammed halfway into the rocket because something does not fit like it did at home.

I would cut the hole between 1/32" and 3/64" oversize as a starting point against the max diameter of the case if you don't have it available to fit the rings to it. The OD can be a closer fit to the airframe as one wants a 0.005" to 0.020" thick bond thickness [0.005" preferred] for typical epoxy. The thinner the gap, the easier the ring is to cock in the tube and jam.

br/

Tony

Good stuff there Tony. Gave me something to think about.

Chuck C.

 

[Rail Dawg]

Another part of the project is getting a trailer/launch pad set up.

I'm thinking a long trailer in the range of 20+ feet with a custom launch rail built on it.

Perhaps 12V hydraulics to do some of the heavy lifting?

Sure would be much easier to have the trailer be an all-in-one with cradles to hold the rocket in transit.

Could use some suggestions on what to have and what to avoid.

Thanks.

Chuck C.

 

[Paulb06]

Another part of the project is getting a trailer/launch pad set up.

I'm thinking a long trailer in the range of 20+ feet with a custom launch rail built on it.

Perhaps 12V hydraulics to do some of the heavy lifting?

Sure would be much easier to have the trailer be an all-in-one with cradles to hold the rocket in transit.

Could use some suggestions on what to have and what to avoid.

Thanks.

Chuck C.

Keep in mind that the RSO will probably require anything flammable like tires etc... to be removed

 

[boatgeek]

Another part of the project is getting a trailer/launch pad set up.

I'm thinking a long trailer in the range of 20+ feet with a custom launch rail built on it.

Perhaps 12V hydraulics to do some of the heavy lifting?

Sure would be much easier to have the trailer be an all-in-one with cradles to hold the rocket in transit.

Could use some suggestions on what to have and what to avoid.

Thanks.

Chuck C.

Others can offer more experience, but it seems to me that transporting the rocket on the launch rail is a bit fraught with chances for disaster. The biggest risk I see in that is that movement of the tower or rocket might rip out a "rail button." You'll need to disassemble the rocket at some point to add charges and pack chutes, so you may as well do that as you assemble the rocket on to the tower. I do like the idea of an integrated tower and trailer with a winch to lift it into position. Your pad slaves will thank you! If you got really clever, you could maybe have the rocket parts slide straight out of their boxes and on to the tower rail in the right position. That would be really cool.

 

[Rail Dawg]

Keep in mind that the RSO will probably require anything flammable like tires etc... to be removed

I hadn't considered that Paul.

Definitely makes a difference in the planning if that is the case. Don't want to remove tires so the pad would have to be separated from the trailer.

Chuck C.

 

[Rail Dawg]

Others can offer more experience, but it seems to me that transporting the rocket on the launch rail is a bit fraught with chances for disaster. The biggest risk I see in that is that movement of the tower or rocket might rip out a "rail button." You'll need to disassemble the rocket at some point to add charges and pack chutes, so you may as well do that as you assemble the rocket on to the tower. I do like the idea of an integrated tower and trailer with a winch to lift it into position. Your pad slaves will thank you! If you got really clever, you could maybe have the rocket parts slide straight out of their boxes and on to the tower rail in the right position. That would be really cool.

I agree it would be really cool. I'm going to email the BALLS folks right now and ask about the removal of tires.

Oh and we're not going to transport the rocket mounted on the rail. The rocket would be set into padded cradles for the ride.

Keep the ideas coming!

Chuck C.

 

[Theory]

Thinking about the airframe / coupler and centering ring structure. From what I see, you are building something crazy strong: CR, coupler, CR; all tied together with glassed stringers and all thread rods, all repeated 10 or so times, correct?

If im on track here, this structure “is” the rocket with the G12 airframe being along for the ride. If so, why not assemble all of the couplers, rings etc. outside the rocket and then ‘slide’ the airframe over and screw the airframe yo the CRs. A dozen grade 8 screws per ring would be plenty strong and would negate having to crawl/reach into the airframe to glass and would also address any possible issues with the epoxy grabbing / sizing the couplers

Just thinking out loud, but “removing” the confined space of the airframe may make a lot of assembly easier