CRC High power builds

CRC · Feb 21, 2014

Hello guys, I'm starting this thread with my first rocket I'm building that I plan on using for HPR, not just a rocket that could take a HP motor, this one will take one at some point.
I'll be asking for opinions & reccomendations through out I'm sure, so please try to keep me from doing something dumb

I'll start by saying this rocket will be used for mid F's-mid H's & will be launched most of time with G's but it will be a back up for level 1 cert.
It is an aerotech HV Arcas, It came with a damaged upper BT so I got to wait to get the replacement before I can complete it, but I'll still have lots to do in the meantime.
Here is the come with contents of the kit with pics of tube damage(big thanks to Pavel for replacing the tube for me)

DAllen · Feb 21, 2014

CRC said:
Hello guys, I'm starting this thread with my first rocket I'm building that I plan on using for HPR, not just a rocket that could take a HP motor, this one will take one at some point.
I'll be asking for opinions & reccomendations through out I'm sure, so please try to keep me from doing something dumb
I'll start by saying this rocket will be used for mid F's-mid H's & will be launched most of time with G's but it will be a back up for level 1 cert.

Do you realize that you will need to modify it to take H's? The stock motor mount is only long enough for the Aerotech G motors. It can be done just keep that in mind while constructing it. Also, an H - even a small one is going to poke this little guy a looooong way up there. You want to consider the field you are flying in and the conditions. I would try a few flights on some big G motors and see how it does before jamming an H in it.

CRC · Feb 21, 2014

Yes I do realize that I'll need to modifiy it & it will go high on an H, this is why I got this kit, so I can still fly it at my field with G's yet still have it as a back up for cert if needed. First flight will be a F20-4W, then G77-7R, then a small H, Ill post pics of parts I've added & took away from original kit after dinner.

nute · Feb 21, 2014

CRC said:
Yes I do realize that I'll need to modifiy it & it will go high on an H, this is why I got this kit, so I can still fly it at my field with G's yet still have it as a back up for cert if needed. First flight will be a F20-4W, then G77-7R, then a small H, Ill post pics of parts I've added & took away from original kit after dinner.

This will be an interesting build. I'm finishing up an Astrobee-D (basically this kit extended with some scale parts) also modified for HPR. A member of the club I fly with (Onebadhawk) gave me an HV Arcas, and as a test flight I flew it on a G64W. Sims estimated well over 1400ft. and It easily reached that. Even a tiny H165 will really get this baby moving. I believe in fly what you like for certs, and if you like high and fast, then that'll work just fine with a large field.
Also, I don't know what you're planning to use for a cert, but personally I would strongly recommend some practice with building RMS motors before betting your cert, biggest/newest rocket, and new RMS casing on it. A way around this would be to use Aerotech's single use H135 or similar motor though.
I'll be watching this thread closely!

CRC · Feb 21, 2014

DAllen said:
The stock motor mount is only long enough for the Aerotech G motors.

12" is stock Motor tube, thats not long enough for a 29mm H? The aerotech sumo level 1 uses the same motor tube.

Here is pics of parts I'm using, note no motor hook or thrust ring

I've added my 3/16" baffle style sc mount, welded 3/16" eyebolts, 1" rail guides & kevlar 1500# line, 490# swivel, not sure if I should use the cooling mesh, anybody have thoughts or experiance using cooling mesh in HPR, I see the at sumo kit uses the plastic baffle & a piston, but not cooling mesh.
My thought was to use the plastic at baffle & my baffle style sc mount, but not sure if thats enough to keep my chute or sc from burning.

DAllen · Feb 21, 2014

CRC said:
12" is stock Motor tube, thats not long enough for a 29mm H? The aerotech sumo level 1 uses the same motor tube.

OH! Well that's a different pile 'o parts than I remember the last time I built an AT kit. Usually the length of the tube didn't determine the longest motor it was the baffle at the end of the tube that limited motor length...

1tree · Feb 21, 2014

There are not two things needed to stuff an H into that rocket:
1) Leave out their cooling mesh
2) leave out their engine block in favor of a retainer ring or other similar item.

When I built mine, I also put in plywood centering rings, though I am not really sure that was needed. I launched on an Aerotech H128 and it went to 2350 feet in a beautiful flight.

Kirk

CRC · Feb 22, 2014

nute said:
This will be an interesting build. Also, I don't know what you're planning to use for a cert, but personally I would strongly recommend some practice with building RMS motors before betting your cert, biggest/newest rocket, and new RMS casing on it. A way around this would be to use Aerotech's single use H135 or similar motor though.
I'll be watching this thread closely!

Good idea about practicing with rms reloads.....since me or my buddy never seen one, let alone build one, really I'm not certing, my buddy is first. I'm just trying to make sure he has a back up plan, cause right now he don't. I still dont even own a 29mm casing. But eventually I will along with eventually I'll cert.

1tree said:
There are not two things needed to stuff an H into that rocket:
1) Leave out their cooling mesh
2) leave out their engine block in favor of a retainer ring or other similar item.

When I built mine, I also put in plywood centering rings, though I am not really sure that was needed. I launched on an Aerotech H128 and it went to 2350 feet in a beautiful flight.

Kirk

Good info, when you say "when I build mine" are you talking about an AT Arcas? I'm using an estes 29mm retainer & I guess I get to save my cooling mesh for another project.
I wonder if I should laminate some cardstock rings onto the aerotech centering rings just to add strength & more gluing surface.....anybody have thoughts about that?

GRIFFIN · Feb 22, 2014

Just build it stock (without the mesh or a motor hook). I have flown one of these on a H399 (trying to rip off the fins) and it flew like a champ. Pretty straight forward build. Like others have said, dont limit yourself to the motr length by adding any sort of hook retainer or Errortechs mesh "stuff"

DAllen · Feb 22, 2014

CRC said:
...I guess I get to save my cooling mesh for another project.

I'd throw it out. It's pretty worthless IMHO. Either use an open chamber style baffle a la Semroc, nomex chute protector, piston or (my favorite) oodles of dog-barf.

-Dave

CRC · Feb 22, 2014

Well I dont think I'll throw the mesh out, after all I do got dishes

So progress & the build has started.....
1st pic: I measured out the finlock rings with the estes retainer I'm using & discovered I have to move the finlock rings ahead a bit to allow the estes retainer to fit all the way on with the rear centering ring behind the retainer, you can see pencil mark where stock says it should be. 1st f-up avoided

2nd pic, I got the rings & mid centering ring CA'd in
3rd pic: I attched my 1500# kevlar coard to my baffle style sc mount I made from a 1/4" bulkhead(not 3/16 like I said before)
Now big decision is do I use the stock 8' aerotech sc or a fabric store 12' braided elastic sc, either one will be attached to the kevlar loop. Which would you guys use? Also I Cd'd the knot on the kevlar loop

1tree · Feb 22, 2014

Yes sir, it was the exact same rocket. Now for another word of advice, do NOT use an Estes retainer for the motor if you intend to fly HP.

The issue is that the thrust ring on an HP motor is about double that of the mid power (such as the 29/40-120 case. Thus there isn't as much bite for the retainer when you put in your HP. And many people fly this just for without incident.

Now I will go public with my error and hope others can learn. You see I was a bit behind the curve and rushed the end to be ready for HP launch, and the coupler was on the long side to hold the rocket together. That then jammed at the ejection charge. The ring holding the motor gave loose and the casing went flying. Now I happened to get extremely lucky in that the thing landed a couple feet from where another rocket landed under chute. Thus my casing was not gone forever, but I can say I won't use Estes for a HP rocket. Plenty good for mid power. And if the thrust rink of HP wasn't as thick, it would be fine for that as well.

In the end, I decided the rocket gods didn't want me to own that model of rocket. You see, this was actually a warranty replacement after the original had a motor crack and blow flames out the side at ignition. But it was a beautiful flight even if the landing ended its usefulness.

Sent from my iPad using Rocketry Forum

CarVac · Feb 22, 2014

1tree said:
Yes sir, it was the exact same rocket. Now for another word of advice, do NOT use an Estes retainer for the motor if you intend to fly HP.

The issue is that the thrust ring on an HP motor is about double that of the mid power (such as the 29/40-120 case. Thus there isn't as much bite for the retainer when you put in your HP. And many people fly this just for without incident.

Now I will go public with my error and hope others can learn. You see I was a bit behind the curve and rushed the end to be ready for HP launch, and the coupler was on the long side to hold the rocket together. That then jammed at the ejection charge. The ring holding the motor gave loose and the casing went flying. Now I happened to get extremely lucky in that the thing landed a couple feet from where another rocket landed under chute. Thus my casing was not gone forever, but I can say I won't use Estes for a HP rocket. Plenty good for mid power. And if the thrust rink of HP wasn't as thick, it would be fine for that as well.

In the end, I decided the rocket gods didn't want me to own that model of rocket. You see, this was actually a warranty replacement after the original had a motor crack and blow flames out the side at ignition. But it was a beautiful flight even if the landing ended its usefulness.

Sent from my iPad using Rocketry Forum

It's OK with a CTI high-power motor because they have the same 1/4" thrust ring length as the hobbyline case.

CRC · Feb 22, 2014

CarVac said:
It's OK with a CTI high-power motor because they have the same 1/4" thrust ring length as the hobbyline case.

Bingo!!! Thats what I have read & seen in an awesome detailed pic/discription from a fellow member(cant remember who or what thread) Estes retainers fit cti casings better then aerotech for the reason 1tree gave, AT thrust ring thicker. Also I'll be going with CTI casing since I've heard aerotech casing dont last as long since the aluminum is a lil thinner, dont know if thats true, but it's what I heard.
Only downside of estes retainer I know of is the heat can damage them easier, but hopefully only the cap would get damaged & therefor easily replaced for an affordable cost.

Shock coard though....8' stock, or 12' fabric store braided elastic?

nute · Feb 22, 2014

CRC said:
Bingo!!! Thats what I have read & seen in an awesome detailed pic/discription from a fellow member(cant remember who or what thread) Estes retainers fit cti casings better then aerotech for the reason 1tree gave, AT thrust ring thicker. Also I'll be going with CTI casing since I've heard aerotech casing dont last as long since the aluminum is a lil thinner, dont know if thats true, but it's what I heard.
Only downside of estes retainer I know of is the heat can damage them easier, but hopefully only the cap would get damaged & therefor easily replaced for an affordable cost.

Shock coard though....8' stock, or 12' fabric store braided elastic?

Abandon Aerotech? How could you?!
Jk :wink: the CTI will be much easier to assemble, and you do have the aforementioned size benifit. I personally love Aerotech for the low cost of reloads, but being in Canada maybe you guys have some do sort of discount or somethin... either way, flying what you like and a re comfortable with is the most important.
However I must say that I used the estes retainer on my L1 cert rocket and it has stood up fine to so far 2 HP motors without problem. I plan to use them whenever possible in my future HP builds. Personally, I trust them on HPR motors, but again being Comfortable is the most important.

Edit: for the shock cord I vote 12'. However, on a HPR rocket, tubular nylon or similar is ideal.

Nate

1tree · Feb 22, 2014

And the learning goes on as I didn't know the CTI ring was thinner. As for the heat, I think far too many people over concern themselves with it. I have yet to see any reports of the ring melting. And honestly, I do believe that you would likely have more problems than the melted ring from that heat.

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CRC · Feb 22, 2014

nute said:
Abandon Aerotech? How could you?!
Jk :wink: the CTI will be much easier to assemble, and you do have the aforementioned size benifit. I personally love Aerotech for the low cost of reloads, but being in Canada maybe you guys have some do sort of discount or somethin... either way, flying what you like and a re comfortable with is the most important.
However I must say that I used the estes retainer on my L1 cert rocket and it has stood up fine to so far 2 HP motors without problem. I plan to use them whenever possible in my future HP builds. Personally, I trust them on HPR motors, but again being Comfortable is the most important.

Edit: for the shock cord I vote 12'. However, on a HPR rocket, tubular nylon or similar is ideal.

Nate

Easier to assemble is good, however you are correct they are more $ then aerotech, even for us Canadians, Yeah tubular nylon would be ideal, but I don't have any, & this will not be a strictly HPR so I figured elastic coard would work. I assumed longer is better for a SC since I'm not concerned about weight & will have enough space to BT, but I know what assuming can lead to. If anyone else thinks 12' is better then 8' then thats what I'll go with, although I like the look of the black AT one lol
Here is a few more pics of my progress,
1st pic: I cut out fin can tubes
2nd pic: I got plastic AT baffle & forward CR CA'd on, no mesh inside

CRC · Feb 22, 2014

1tree said:
And the learning goes on as I didn't know the CTI ring was thinner. As for the heat, I think far too many people over concern themselves with it. I have yet to see any reports of the ring melting. And honestly, I do believe that you would likely have more problems than the melted ring from that heat.

Sent from my iPad using Rocketry Forum

Good to hear you have not heard of any melting, singeing is ok(adds caracter) I just fear, plastic + heat, could be bad.

Rex R · Feb 23, 2014

to answer your question(that you posed in the mid power section), the kit was designed for 'thick' (gel should work) CA. I've worked with this type of plastic before...epoxy will form a weaker bond than the CA, you also need to be careful about which paint you use.
Rex

CRC · Feb 23, 2014

Rex R said:
to answer your question(that you posed in the mid power section), the kit was designed for 'thick' (gel should work) CA. I've worked with this type of plastic before...epoxy will form a weaker bond than the CA, you also need to be careful about which paint you use.
Rex

instructions say use Med viscosity CA, I've never used the gel, but I'm using Gorilla brand, which seems to be med, I don't know what if any diff there is other then dry times. Good info about the bonds, thanks, paint.....yes that can always be ummmm fun.

CRC · Feb 23, 2014

Here is a few more pics....
1st pic: I drilled holes for rail buttons
2nd pic: I drilled the forward one too low so I had to do this to make the centering ring clear the button
3rd pic: Flange nut that centering ring had to clear
4th pic: my baffle style sc mount with welded 3/16" bolt I will scew into the AT baffle, so it will be strong, maybe overkill, but I like it.
One queston for you HP experianced, will my holes be big enough to allow gasses through to deploy properly? (2.6" diameter BT)

Rex R · Feb 23, 2014

I'd go with between 0.75 and 1 square inches of 'hole' area for your baffle.
Rex

CRC · Feb 24, 2014

Thanks rex, so is it safe to say around 1/4-1/3 of BT size to be "open" for a baffle to work properly?

So I got my buttons & LL on along with my fins, I did beads of CA inside, but now I'm going to apply epoxy over everything in fin can, just to lock everything in there real good.

Rex R · Feb 24, 2014

here is the baffle that I did for my argent. the plate covers 2/3s of the opening.
Rex

CRC · Feb 24, 2014

One day I'll try the semroc style baffle.
More progress pics
1st pic: got the rear centering ring in after spreading epoxy on everything in the fin can
2nd pic: I got the bulkhead on the coupler with welded eye bolt
3rd pic: I got the 1st of 4 fin can segments CA'd on(not sure if I should blend the edge of it in with glue or leave it with the lip)
4th pic: My Baffle style sc mount. I'll add gussets later, & I can admit I didnt get it screwed into the AT plastic baffle as much as I wanted. prob only half a turn, but there is epoxy on it so that will be attached, plus it will have the gussets and epoxy all around, I think that should hold the shock cord in there.

CRC · Feb 25, 2014

Got my fin can segment made & on for other side with buttons.....queston though, since I've yet to use or see a rail, will this work with the raised fincan section? or will I have to make a standoff/raise the buttons. I really hope I can just fill around cutout with glue or filler without it affecting the button on rail.

Rex R · Feb 25, 2014

the rail slides/uses the channel in the button. so as long as the shoulder next to the airframe is above the level of your cutout, you should be good. remember, to 'reduce wear', the button should be free to rotate.
Rex

DAllen · Feb 25, 2014

Rex R said:
the rail slides/uses the channel in the button. so as long as the shoulder next to the airframe is above the level of your cutout, you should be good. remember, to 'reduce wear', the button should be free to rotate.
Rex

Reduce wear? Is there any evidence this is happening? If your buttons are getting worn then your club needs to get off their lazy butts and clean the rails once in a while. Or just replace them.

This is the second time I've heard this in less than a month and I have never heard it before. I still have my L1 rocket from '07 with 30+ flights on it and have yet to see ANY wear on buttons that are screwed on tight. I've flown that thing not just at our club but dang near every launch I've been to. Seems like a little bit of excessive engineering for something that is probably not going to happen. I can take pictures if you want...

CRC, I would make a little stand off for that button which can be done a number of ways. The simplest being getting a plastic/delrin washer from the hardware store and put it under your buttons. What I see in the photo will likely work but your paint is going to get scratched.

-Dave

CRC · Feb 25, 2014

Thanks guys, by the sounds of it I think I'll add a washer to raise the buttons slightly, since I dont want any binding or paint scratching. Trick is I only need it a hair higher.
I'm not getting into what way is right but I will say on rail instructions it says to tighten screw all way, then back it off just enough the button spins freely.
Here is some more progress pics....
1st pic: got another fin can segment on
2nd pic: I got the rear centering ring & retainer CA'd in with cr having a bead of wood glue around it(CA underneath)
3rd pic: my gussets(not sure what rocketeers would call them) for sc mount. I still got to epoxy all that in place.

DAllen · Feb 25, 2014

CRC said:
Thanks guys, by the sounds of it I think I'll add a washer to raise the buttons slightly, since I dont want any binding or paint scratching. Trick is I only need it a hair higher.
I'm not getting into what way is right but I will say on rail instructions it says to tighten screw all way, then back it off just enough the button spins freely.

Well, I certainly don't agree with that instruction but whatever. I bet it will work just fine either way. But if you happen to notice a lot of crud where the rail makes contact with the button then it is high time for a rail cleaning. All it takes is; power washer + steel wool + elbow grease and not necessarily in that order.

Another thing you will find as you get into this hobby is the local hardware store is your friend. All sorts of solutions for your rocketry design conundrums exist there. Sometimes I find solutions just by walking around and looking at stuff and then it’s almost like it jumps out at me. The washers for example I use when I know I am going to put a lot of extra time into painting a project. It’s a cheap, easy and effective solution.

CRC High power builds

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