DD Scion for L1 Build Thread

So I've been posting a lot about my L1 cert. Many builds and build ideas. I've been advised against DD. I've been advised to use DD. I've been told to build a heavy rocket. I've been told to do what I want. And my first try failed on it's test flight thanks to wind. So I've considered it a lot. Thought it all through. Made my decision.

My thoughts lie in the idea that success is the goal. The singularly important goal. Based on my observations, studies, and advice, I have decided that DD does not worry me. It's something that can be scientifically calculated and made redundant. I want to run everything from a baby G to an I200 in this rocket. That means a light rocket. Light means high alt. High alt means DD.

So my decision has been to build a DD Estes Scion. I'll be using the base kit with minor modifications. The coupler will be my a/v bay. I'll be replacing the stock 4" coupler with a 6" coupler from BMS. Obviously there will be SS forged eye bolts, SS all thread rod and hardware and 1/4" tubular kevlar shock cord. I still need to figure out how I'm going to work with the nose cone. I dont think I want to use the stock mounting point. I'm not aware of any coupler or tubing that will fit snuggly inside the shoulder and I doubt the shoulder will be long enough if I cut it off above the slanted section. Any suggestions to resolve this?

I've also started reinforcing the ends of the body tubes. I've used both CA soaks and epoxy inside the ends of the tubes then sanding smooth. Will epoxy bond strongly to cured epoxy? Or even to cured CA? I'd like to reinforce the fin canister of the sustainer but I'm worried about the bond. Also, what is the best lightweight, small charge canister I could use? I'm not against the tape wraped charges, but I'd feel more comfortable with a directional charge. I believe I have everything else ready and the RockSim file will be completed tonight.

Yes.

:lol:

Actually, I was just thinking earlier today about your thread about the 4" PAC-3 as a L1 attempt and was thinking of suggesting to you another rocket which you can do shakedown/test/warm-up launches on G motors first (so many to choose from too!). I feel it's better to know how a rocket flies before you take it up to the next level rather than just taking it to L1 on the first launch with your fingers crossed.

The Scion sounds like a good choice...if you want, you can fly it first without DD, then with DD and then try for L1. Also not too much $$ in case anything goes wrong. I'll let others answer the other questions since it seems that when I answer something early, it ends up being countered by the next 4-6 people.

Pfft. Post your opinions. It's always nice to see several options, opinions and ideas, but at the end of the day, it's up to the OP to filter and decide. I have many of my own opinions about rocketry, not shared by others, yet I still stand behind it. What works for one may or may not work for another. Even with my limited HPR experience, I have seen designs for the guts of several rockets I would never attempt. Either I feel they are unnecessary, overly complicated or just plain too far out there. the K.I.S.S. rule applies in most areas. But advancement requires risk. I just prefer to limit the risk and go with what I understand. What makes sense. So share yours and let me see if it makes sense.

Why use ss hardware? Zinc plated cost less and is ample for our applications.

The NC is a really easy fix. Just drill two holes largest enough for Kevlar in it. Tape the end of a 12" piece of Kevlar to keep it from fraying, then thread that into the NC through the hole and back out the other hole. Tie that Kevlar into a loop and you have a very robust attachment point.

You can absolutely do this for an L1. I have flown an almost stock PSII Nike Smoke (just a few oz of nose weight) on an H97 for a beautiful flight. I also have a cardboard 2.6" PAC-3 that I fly on I200 motors. These cardboard airframes are just fine on strength.

Also, don't shy away from DD. Just be deliberate in your prep, and everything will be fine.

One way to extend the NC to add length to the main chute payload bay is to drill all the way through the nose cone about 1" below the tip and put 2 brass pins (1/8" diameter is good) in at right angles to each other, making sure a loop of kevlar for shock cord attachment goes around the pins. Then fill with epoxy over the pins securing the kevlar loop. The loop should be long enough to hang out of the base of the nose cone a bit, of course all this is done after removing the sloped section of the Scions shoulder. Due to the lightweight nature of the Estes airframe a friction fit may be a better choice than shear pins on the main, or you can make special provisions to reinforce that area so the 2-56 nylon screws don't prematurely wear out the forward section of the airframe.

Using the 6" BMS coupler for the Av-Bay is a good choice, order 2 while you are at it and split one down the side and use it to double the coupler similar to a Loc Stiffy (yep I posted this in your other thread too.) Metal Hardware is really not necessary other than quicklinks on this build, as lightweight as the rocket is you could probably use nylon allthread in the Av-Bay and save some weight. Bulkheads could be made from 1/8" ply with a basswood step on the inside of the Av-Bay bulkheads. Epoxy really is unnecessary in most of the build as it adds a lot of weight, Carpenters wood glue, and Trim and Moulding glue will do the bonding and fillets nicely and save a lot of weight.

I would also recommend pvc or copper pipe fitting as charge wells, the Estes 3" tube might be a little light for a rubber glove type BP charge going off right next to the wall of the airframe, and directing the pressure up rather than out towards the airframe walls might help protect the cardboard from damage.

All of this is my opinion and how I plan on building my Scion as a DD. As for L1 as DD go for it if you feel comfortable, lots of people told me not to do DD on my L2 and just K.I.S.S. it. Well I did my DD and prepared carefully, my first DD was my L2 and it was successful, I did however keep my motor ejection as drogue backup and it may or may not have been what seperated the airframe (the drogue charge did go off).

Well my build is on a very temp hold. Mother in law is arriving Thursday. Plus I've hit a snag. I wanted to upgrade the mmt to 38mm. Will this thing even survive the mach transition? Its a concern that popped up tonight.

rharshberger said:

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Using the 6" BMS coupler for the Av-Bay is a good choice, order 2 while you are at it and split one down the side and use it to double the coupler similar to a Loc Stiffy (yep I posted this in your other thread too.) Metal Hardware is really not necessary other than quicklinks on this build, as lightweight as the rocket is you could probably use nylon allthread in the Av-Bay and save some weight. Bulkheads could be made from 1/8" ply with a basswood step on the inside of the Av-Bay bulkheads. Epoxy really is unnecessary in most of the build as it adds a lot of weight, Carpenters wood glue, and Trim and Moulding glue will do the bonding and fillets nicely and save a lot of weight.

I would also recommend pvc or copper pipe fitting as charge wells, the Estes 3" tube might be a little light for a rubber glove type BP charge going off right next to the wall of the airframe, and directing the pressure up rather than out towards the airframe walls might help protect the cardboard from damage...

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I agree.. but in the spirit of K eeping I t S imple S ir ..

Would suggest a Blue Tube coupler if it is the correct diameter ..since you are talking to BMS anyway.

Because you are looking to Shed weight there is Aluminum all thread available.. I got mine at Grangers.

Grab a set of charge wells from Dog house and their great terminal blocks.

Never too early to start working with Fiberglass av bay lids .. they are thin and fireproof. Dont forget a bulkhead for the nosecone too

Kenny

KenRico said:

I agree.. but in the spirit of K eeping I t S imple S ir ..

Would suggest a Blue Tube coupler if it is the correct diameter ..since you are talking to BMS anyway.

Because you are looking to Shed weight there is Aluminum all thread available.. I got mine at Grangers.

Grab a set of charge wells from Dog house and their great terminal blocks.

Never too early to start working with Fiberglass av bay lids .. they are thin and fireproof. Dont forget a bulkhead for the nosecone too

Kenny

Click to expand...

Unfortunately, its not the same diameter as bluetube. It's 3.0 OD and the LOC is 3.1 OD. The tube material and thickness is what reminded me of the LOC tubing. I do have the plywood bulkheads for this tube from BMS. And I'm getting the 6" coupler. I'm really just worried about the tubing surviving mach at this point.

KenRico said:

I agree.. but in the spirit of K eeping I t S imple S ir ..

Would suggest a Blue Tube coupler if it is the correct diameter ..since you are talking to BMS anyway.

Because you are looking to Shed weight there is Aluminum all thread available.. I got mine at Grangers.

Grab a set of charge wells from Dog house and their great terminal blocks.

Never too early to start working with Fiberglass av bay lids .. they are thin and fireproof. Dont forget a bulkhead for the nosecone too

Kenny

Click to expand...

3" Blue tube couplers are too large diameter (2.997" OD) for Estes 3" (2.93" ID).

Aluminum threaded rods are easy to custom make with a hack saw and some 1/4" aluminum rod, if you have a 1/4-20 threading die, if not buy them (not that the die is expensive, its about the most common size).

I don't like terminal blocks nor do many members of my club, the reason is they can be a point of failure/loss of connection between the igniter and altimeter, a terminal block uses 3 connection points (unless it is soldered on one side, then its two). I would like to suggest two methods one I currently use and one I am switching to using.

Method 1: Drill a hole through the bulkhead large enough to fit a Well Nut of what ever size you choose, I then file a slot in the edge of the hole large enough to put the wire mostly in, then I push the Well Nut into the hole and tighten, the hole is now sealed and the igniter can be wired directly to the altimeter. This is the method I currently use and the well nuts are available at my local Ace Hardware, Lowes and HD.

Method 2: Drill hole for a #4 or #6 machine screw though the bulkhead, take piece of brass (or other stiff metal) about .25"wide by 1" long about 1/8" thick, drill a hole for the machine screw near one end. Put machine screw through hole in metal strip and bulkhead holes, but a nut or tee-nut on backside of bulkhead (strip should pivot around screw). Determine where to drill a 1/8" hole through bulkhead that will be about .25" beneath the solid end of the brass strip. Pass igniter wire through this hole. Take some Elmers Poster Tack (putty type non-permanent adhesive, just a square piece about .25") and press it firmly over the wire and hole, loosen screw enough to place metal strip over poster tack and wire, then tighten screw and the poster tack seals the hole through the bulkhead, again you directly wire to altimeter. This method is the one I am switching too due to ease of use and the fact that the poster tack is very cheap and it can be reused a number of times before it needs to be discarded.

The well nuts and homemade threaded rods are shown in the pictures below, the two pics on the left and center are from my L2 rocket, and the right one is the from my L1 Crayon rockets nose cone Av-Bay.

I'm not trying to step on Kennys post he has good advice and probably far more experience than me, the above is just how I do it.

This is an aggressive L1 build, and with a few strengthening techniques, you could build a Scion that can take an I200... but probably not a "baby" G (too heavy). I'm not real familiar with the Scion, but Estes materials are known to be on the light side, so any amount of strengthening, such as composite laminating (glassing) 0f the tubes would be a plus for those high thrust H and I-class motors. What is your cert motor of choice?

Time to revisit this thread.. getting my buddy a Scion for his birthday.

Maybe i will build my Partizon so we can drag race

Kenny

I made a Leviathan dual deployment once. Those materials are not made for the rigors of a typical configuration; would use small charges and tape friction if I did it again.

Kruegon said:

Well my build is on a very temp hold. Mother in law is arriving Thursday. Plus I've hit a snag. I wanted to upgrade the mmt to 38mm. Will this thing even survive the mach transition? Its a concern that popped up tonight.

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I like the idea of doing DD for your L1 and going with 38mm. I scratch built a DD 38mm rocket for my L1. What I don't quite agree with is using the Estes kit as a basis of the build. I have a Leviathan I have flown with H128W and H250G AT motors and the H250G seems to have wrinkled the BT some just above the upper CR. I would not recommend Estes tubing for a rocket that will fly the full range of L1 motors (i.e. 38mm) unless you put one or two wraps of fiberglass cloth on it. A couple of wraps of 3 oz. should work fine. Of course, the option is to just scratch build it with LOC tubing.

What I ended up doing was getting my L1 cert with an I motor and then ended up using I motors for the first 6 flight or so. I also flew it a couple times on an I1299N-P and after getting my L2 I also flew it on a J350W AT motor. My point is, by using a rocket designed by Estes for MPR flights, you are structurally limiting what you can do with it in the future. I would recommend you design/build a rocket for the full range of L1 motors because you will want to fly it on those at some point.

Don't worry about the DD, once you get a little experience with DD, I think you will want to use electronic deployment for all your flights.

Good luck on the L1.