Back to the Drawing Board for LVL 2

[Dragoon]

Ok so i went to AirFest this weekend and attempted my LVL 2 and failed due to putting a very large motor in a rocket that wasnt meant for J impulse. Needless to say it failed and im back to the drawing board and while i was at AirFest i picked up an Intimidator 4 for a steal and even though the plan was to eventually make it my LVL 3 (before the destroyed rocket) im now going to make it my LVL 2 and go low and slow on this one.

That being said please by all means give your 2 cents over the course of this build so that i may learn even more than i already have this weekend and hopefully have a successful flight whenever that happens. So without further ado im keeping with rocket tradition and doing a dorky dry fit of the rocket because i hope it gives me good rocket karma down the road when i need it.

AS A FINAL SIDE NOT. i would like to sincerely thank all those that put up with my 4 Billion questions this weekend i really do appreciate it............specific shout outs to Wildman and Jackie of course, Crazy Jim, Tim Sapp, all the guys from Carolina Rocket Composites, all the guys from the St Louis Rocket club, and anyone else that ive forgotten seeing as how im terrible with names.

 

[DavidMcCann]

sucks you dropped the first, but learning from failure is a good thing.


This is a BIIIIIIIg L2 bird.....but drop a nice L in there and that's doing it in style

 

[tim cubbedge]

I have the 3" version and it screams on J motors. Put an L1115 in it for your cert flight, awesome motor!

 

[Dragoon]

to be honest ill probably still do it on a J and only send it to 2k for the cert flight so i have a better chance of getting it back................then ill put the big motor in it

 

[DavidMcCann]

That size, a little juice is a safer flight

 

[noffie79]

Maybe you could split the difference and go with a K motor this time. More robust than a J, but not as big of a kick in the pants as an L. I imagine a K550 would give it a decent ride.

 

[sharkbait]

That size, a little juice is a safer flight

+1.

Under powered and low end thrust flights often end in a bad way.

My I-4 doesn't allow me to put anything smaller than a K in it

 

[markkoelsch]

Build it and document it like a L3. Then adapt to a 54mm K motor for your L2.

My L3 is a Wildman Extreme. Test flight on AT K805 to about 4K'. Works great.

 

[Dragoon]

So i got to work on my I-4 a little more this evening...... i worked on building the MMT

For this build im doing something that ive found that works well and thats gluing the kevlar shock cord all the way through to the bottom of the MMT and epoxying it the whole way up so i started working on that a little bit got my kevlar cut to the right size and tacked in place before i epoxied my top 2 centering rings in place

I also cut out the BT so that i can pre build the fin can and just slide it in when its ready as ive been told works really well by a lot of people so this is the first time i will be trying this i hope it goes well.............all input here is most certainly welcome..............i also cut off a 1/4" of coupler to glue into the bottom of the BT to give the ass end a bit more strength but i forgot to take a picture

Also since i work on airplanes for a living i acquired a sealant tube and applicator and im very pleased with it since i didnt make mongo mess with the rocketpoxy

As usual all the 2 cents is appreciated especially if the 2 cents comes with pictures and examples because im a visual learner thanks

 

[fyrfytr310]

K550, baby! Let'er rip!

 

[cherokeej]

K550 will be borderline for this bird. I fly a Competitor 4, almost identical to the Intimidator. I would suggest a thrusty 2 grain 75, like the AT K1000. If he wants to keep it really low, consider the J800 or the K1100. Use something that will get it off the pad.

Hey Dragoon... Good job. When you tack the fins in place, before you remove the mmt/fin assembly from the body tube to complete it, I find it's a good idea to put a reference mark on one fin and the b/t. then when installing it back into the b/t, I like to put a wrap of saran wrap on the coupler, slip it in behind the fin can, then clamp it with a tourniquet made of tubular nylon. Helps hold the tube round.

And usually on a bird this size, we leave out the shock cord attached to the motor mount. Attach recovery to a cast eyebolt jam nutted to the forward closure of the motor. Strongest point in the entire rocket. But then, that would dictate flying with electronics. Which you'll need for the bigger motors anyway.

Good luck with it this time, brother. Up fast, down slow.

 

[Dragoon]

K550 will be borderline for this bird. I fly a Competitor 4, almost identical to the Intimidator. I would suggest a thrusty 2 grain 75, like the AT K1000. If he wants to keep it really low, consider the J800 or the K1100. Use something that will get it off the pad.

Hey Dragoon... Good job. When you tack the fins in place, before you remove the mmt/fin assembly from the body tube to complete it, I find it's a good idea to put a reference mark on one fin and the b/t. then when installing it back into the b/t, I like to put a wrap of saran wrap on the coupler, slip it in behind the fin can, then clamp it with a tourniquet made of tubular nylon. Helps hold the tube round.

And usually on a bird this size, we leave out the shock cord attached to the motor mount. Attach recovery to a cast eyebolt jam nutted to the forward closure of the motor. Strongest point in the entire rocket. But then, that would dictate flying with electronics. Which you'll need for the bigger motors anyway.

Good luck with it this time, brother. Up fast, down slow.

Well this missile will never be going up without electronics so that's not even a question after losing the last one and one disintegrating I wont be launching anything anymore without a gps in it and since I'm at it I might as well do dual deploy. also I don't have any 54 or 75mm casings or anything like that just yet so I hadn't even thought about the forward closure attachment (which the way its being built I could still technically do) but if you have any of these cases especially the 54mm can you tell me if it has the bolt in that size motor casing

and thanks for the words of encouragement this is just one step closer to the end goal of 100k+ with video of the curvature of the earth

 

[Dragoon]

Since I'm getting closer to putting this MMT into the body tube does anyone have any advice on foaming the fin can particularly what kind and where to get it from and why you like it so much

 

[tbonerocketeer]

Since I'm getting closer to putting this MMT into the body tube does anyone have any advice on foaming the fin can particularly what kind and where to get it from and why you like it so much

Don't foam it.

 

[tim cubbedge]

Don't foam it.

Exactly! You want good internal fillets on that rocket!

 

[Dragoon]

Exactly! You want good internal fillets on that rocket!

wouldn't internal fillets plus foam be even stronger?

 

[tim cubbedge]

I don't know if it will make it stronger but it will definetly add more weight where you don't want it.

 

[dixontj93060]

Do the math (posted by me somewhere on this forum). Typically foam is lighter than filleting if your rocket can stand root edge adhesion and foam only. If you are going to add the higher weight of internal fillets then don't overkill with foam.

 

[Dragoon]

Okie dokie

 

[cherokeej]

Well this missile will never be going up without electronics so that's not even a question after losing the last one and one disintegrating I wont be launching anything anymore without a gps in it and since I'm at it I might as well do dual deploy. also I don't have any 54 or 75mm casings or anything like that just yet so I hadn't even thought about the forward closure attachment (which the way its being built I could still technically do) but if you have any of these cases especially the 54mm can you tell me if it has the bolt in that size motor casing

and thanks for the words of encouragement this is just one step closer to the end goal of 100k+ with video of the curvature of the earth

54mm AT hardware has threaded forward closures available. Not familiar with the 54mm Cesaroni offerings, but the larger stuff in both come with threaded closures for eyebolts. And do not be tempted to use a cheap, bent eyebolt. Spend the dough on the solid cast ones. It is worth it. Especially when you want to fill up that 75mm hole in the bottom.

Yeah, foam isn't the ticket here. Rough everything up, and make good fillets containing plenty of chopped carbon fiber both inside on the mount and outside on the a/f. If you're planning a lay-up, plan and prepare ahead, and do it while the fillets are still green. You'll get a more solid structure.

All this is just my 2 cents. But I've flown a Comp4 as a Rx test-bed for years, and spent 8 years as an L3CC.

And when you fly the bigger motors, you'll wanna remember to pin the nose. Cuz forgetting the pins on a 23K flight makes for a really, really long drive. D'oh!!

 

[NateLowrie]

I don't know if it will make it stronger but it will definetly add more weight where you don't want it.

It'll make it marginally stronger but it a) definitely puts weight where you don't want it and b) is a total pain in the butt if you ever need to fix anything in the fin can.

My advice: Good internal fillets on the motor mount to fin root attachment edge using epoxy with chopped FG/CF. Follow up with good fat external fillets. That should be plenty for your L2. If you want extra reinforcement, Tip to tip fiberglass is a much stronger reinforcement and will be lighter.

 

[ksaves2]

Do the math (posted by me somewhere on this forum). Typically foam is lighter than filleting if your rocket can stand root edge adhesion and foam only. If you are going to add the higher weight of internal fillets then don't overkill with foam.

Ditto, One or the other, not both. If it's easy enough to get in there, lay the internal fillet and call it good. Don't epoxy that aft centering ring. Can use a syringe with epoxy and tubing or run it in. If you epoxied the aft centering ring you can drill holes next to the fins and run it in a' la Wildman method. Download instructions for the Wildman rocket and you'll see what is meant.

For future consideration, where your harness exits through the notches in the forward centering ring, I try to avoid laying epoxy on the harness at the notch. The epoxy makes the fibers brittle. Now you don't have much side to side play in the harness that far down in the rocket so you should be fine. Your tails didn't have to extend that far down and you have plenty area of adhesion. Make darned sure your epoxied harness tails don't end up directly under your fin slots. The root edge is better off
bonding to the motor tube itself and not the kevlar harness. Kurt

 

[Dragoon]

Thanks everyone for the comments on the Foam vs fillets

and luckily i had a moment of brilliance and havent glued the aft centering ring so that should certainly help and the black paint on the tube in the pictures is where the fins will be going