The DAllen and rfjustin 3" Prometheus COMBINED Build Thread - LET THE CHAOS ENSUE

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Welp...."Upset Homer" is loaded up with a J800 and ready to go. Sim sez 5800' and with the forecast tomorrow I don't know we'll ever get a better day to fly this time of year...If successful this will be a new personal altitude record for me.
 
What did you end up using for BP? Mine is currently loaded with 2.0 in the booster and a punchy 2.5 in the top.
 
For the next flight I do plan on pinning the fin can to the ebay. I learned that using tape to make the fit between a fiberglass coupler and body tubes is a PITA unlike paper rockets. So next time I'm going us two 2/56 nylon screws to pin the can to the ebay and up the charges to 2.5g.....In case anyone was wondering lol.

Sooooo I should be getting a camera shroud for this baby tomorrow from Additive Aerospace. Now on a paper/phenolic rocket I think I know how I'd attach it. Just curious what others prefer to do on a fiberglass rocket like this one. I have a few ideas:

- Glue the SOB right to the side of the rocket. Make it permanent.
- Drill 4 holes and use the screws that come with the shroud. Sorta kinda permanent. Could remove the shroud if I REALLY wanted to.
- Figure something else out that doesn't require a commitment. Maybe PEM nuts? Blind nuts that won't interfere with recovery gear somehow...? Maybe something else?

I am kind of leaning toward a solution where I can easily take on and remove the shroud. On-board videos are nice and all but I foresee a point at which where I may want to really push the limit of this rocket (or the limit of my wallet) and may not want the added drag of a shroud just so I can see what it can do. But then like this past weekend I flew it once on a J800 - and subsequently bought ANOTHER J800 for the next flight - now I want an on-board video with that motor.
 
J800

Justin’s rocket might be prettier than mine BUT I GOT MINE IN THE AIR FIRST

NYAH NYAH

:dancingelephant::headspinning:

the adult beverages are going to taste great tonight!!!
Haha, called it. Just not at his drippy fillet stage 🙂

Of course without a liftoff pic or video that could very well be staged 😜
 
For the next flight I do plan on pinning the fin can to the ebay. I learned that using tape to make the fit between a fiberglass coupler and body tubes is a PITA unlike paper rockets. So next time I'm going us two 2/56 nylon screws to pin the can to the ebay and up the charges to 2.5g.....In case anyone was wondering lol.

Sooooo I should be getting a camera shroud for this baby tomorrow from Additive Aerospace. Now on a paper/phenolic rocket I think I know how I'd attach it. Just curious what others prefer to do on a fiberglass rocket like this one. I have a few ideas:

- Glue the SOB right to the side of the rocket. Make it permanent.
- Drill 4 holes and use the screws that come with the shroud. Sorta kinda permanent. Could remove the shroud if I REALLY wanted to.
- Figure something else out that doesn't require a commitment. Maybe PEM nuts? Blind nuts that won't interfere with recovery gear somehow...? Maybe something else?

I am kind of leaning toward a solution where I can easily take on and remove the shroud. On-board videos are nice and all but I foresee a point at which where I may want to really push the limit of this rocket (or the limit of my wallet) and may not want the added drag of a shroud just so I can see what it can do. But then like this past weekend I flew it once on a J800 - and subsequently bought ANOTHER J800 for the next flight - now I want an on-board video with that motor.

I used well nuts secured -inside- the airframe. Goal was to allow the properties of the well nuts to conform to the internal contour of the airframe, while still securing the shroud. This was on a 4" airframe so I had plenty of room to apply pressure while turning the machine screws. I used the shortest screw possible so as to minimize the opportunity of a long screw snagging the shock cord.

Maybe next time I'll machine a block to go on the inside. Or even 3d print. Hmmmm 3d printing a block to go on the inside sounds pretty feasible. Could add some PEM or threaded inserts for more security.
 
For the next flight I do plan on pinning the fin can to the ebay. I learned that using tape to make the fit between a fiberglass coupler and body tubes is a PITA unlike paper rockets. So next time I'm going us two 2/56 nylon screws to pin the can to the ebay and up the charges to 2.5g.....In case anyone was wondering lol.

Sooooo I should be getting a camera shroud for this baby tomorrow from Additive Aerospace. Now on a paper/phenolic rocket I think I know how I'd attach it. Just curious what others prefer to do on a fiberglass rocket like this one. I have a few ideas:

- Glue the SOB right to the side of the rocket. Make it permanent.
- Drill 4 holes and use the screws that come with the shroud. Sorta kinda permanent. Could remove the shroud if I REALLY wanted to.
- Figure something else out that doesn't require a commitment. Maybe PEM nuts? Blind nuts that won't interfere with recovery gear somehow...? Maybe something else?

I am kind of leaning toward a solution where I can easily take on and remove the shroud. On-board videos are nice and all but I foresee a point at which where I may want to really push the limit of this rocket (or the limit of my wallet) and may not want the added drag of a shroud just so I can see what it can do. But then like this past weekend I flew it once on a J800 - and subsequently bought ANOTHER J800 for the next flight - now I want an on-board video with that motor.
I like this option best.... :) "Glue the SOB right to the side of the rocket. Make it permanent."
https://www.rocketryforum.com/threa...-needs-built-first.167169/page-3#post-2185110
 
For the next flight I do plan on pinning the fin can to the ebay. I learned that using tape to make the fit between a fiberglass coupler and body tubes is a PITA unlike paper rockets. So next time I'm going us two 2/56 nylon screws to pin the can to the ebay and up the charges to 2.5g.....In case anyone was wondering lol.

OK, I am wondering! Why do plan to pin the fin can to ebay? Is the fit too loose or wobbly for your comfort? This rocket is probably not prone to drag separation.

In my FG rockets, the fit is usually good enough or I add just a couple tabs of masking tape to tighten things up a bit.
 
I agree that drag separation isn't likely. However, the fit at that connection was just too loose IMHO. I put tape on the ebay and when I slid the BT on it just scrunched the tape up and made a mess of the situation and I spent a lot of time in the field screwing around with tape, re-sliding the BT on, pulling it off, putting more/less tape on, etc. I figure it might be easier (and less frustrating) to just slide the BT on and pin the sucker. I donno maybe I need to play with it some more at home....maybe I was a little wound up with launch fever in the field lol.
 
I agree that drag separation isn't likely. However, the fit at that connection was just too loose IMHO. I put tape on the ebay and when I slid the BT on it just scrunched the tape up and made a mess of the situation and I spent a lot of time in the field screwing around with tape, re-sliding the BT on, pulling it off, putting more/less tape on, etc. I figure it might be easier (and less frustrating) to just slide the BT on and pin the sucker. I donno maybe I need to play with it some more at home....maybe I was a little wound up with launch fever in the field lol.
Dave,

If you have time, try thin aluminum tape in non wide strips (2 or 3 at about 1.5 to 2 inches long by 1/2 inch wide)) placed vertically towards the bottom of the AV-bay but not infringing the bulkhead to booster joint. In either case (aluminum tape or shear pins)-I'd repeat ground testing
Fred
 
I put tape on the ebay and when I slid the BT on it just scrunched the tape up and made a mess of the situation
That sounds like the inside edge of the fin BT is too sharp.
Deburr/round the inside BT edge with sand paper. Then it will slide over the tape and not catch the tape scrunching it up.
 
That sounds like the inside edge of the fin BT is too sharp.
Deburr/round the inside BT edge with sand paper. Then it will slide over the tape and not catch the tape scrunching it up.

Omg why didn't I think of that??? That's a easy solution...thanks
 
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