I call it "The Trident"

[Nate]

Ok, just came up with a really cool idea. you probably won't use it, but it'll look so cool I might just cry.

First, cant all the fins about 1 degree in the same direction so you get a low rate of spin on the rocket.

Second, put smoke cannisters in the outboard instead of motors so you don't have to worry about it shredding or being unstable or anything.

Third, but a smokeless hybrid in the main so that the only smoke visible will be three white columns braiding around themselves during flight.

Can you picture that? woah.

 

[BobCox]

Originally posted by Nate
... three white columns braiding around themselves during flight.
Can you picture that? woah.

That would be wicked cool!

 

[Gunny]

I have already put a nice chamfer on the leading and trailing edges using a 22.5° router bit. However, I will incorporate the conduit along the trailing edge as a few of you have recommended. I found some miniature brass tubing at McMaster-Carr that should work quite nicely.

I want to thank you all for your suggestions, recommendations, and support. I was already pretty excided about this build, but due to all your enthusiasm… now I’m totally stoked!

I will post some build pics when they become available and most definitely coverage of the flight-ops as they progress towards the big one.

Keep the feedback coming… great stuff.

 

[speedyweasel]

Just a thought about the spiralled smoke post... you could still accomplish this goal even with the rocket assembled. Simply use your router (or better yet, a RotoZip [or similar]) to modify the leading edge bevels.

You mentioned it's a 45° angle (22.5° x 2) but if you modified that to, say, 70 degrees in one direction that would induce a nice, slow rotation to achieve the same effect as canting.

 

[BobCox]

You could also acheive the same effect without modifying the fins by mounting the wiring conduits on the face of the fins instead of on the edge. If you put them all on the same side, they will act like spin tabs.

 

[speedyweasel]

Dang, Bob... that's not a bad idea, either. The only downside I see to that is it's more draggy than a modified bevel.

 

[SpartaChris]

Originally posted by Manwithbeers
Sorry, but, if that were my rocket I would scrap the plan and use the parts in real rockets. The design is just too dangerous. If I were an RSO at a launch that rocket would never see a pad with motors on the fins.

If you really plan to build this I suggest you find an RSO who will let you fly it. Otherwise I think the only chance for you to see it fly is at a non public, un-insured launch where there is no danger of damage to personal property. Or at least where you will be responsible for the risks.

I completely disagree with your sentiment. If I were an RSO, I would certainly let it fly. It has to be at one of the far away pads anyway, so I see no reason why it shouldn't be able to get off the ground.

Several "head's up" announcements prior to flight would be a good idea too.

 

[Nate]

Originally posted by SpartaChris
I completely disagree with your sentiment. If I were an RSO, I would certainly let it fly. It has to be at one of the far away pads anyway, so I see no reason why it shouldn't be able to get off the ground.

Several "head's up" announcements prior to flight would be a good idea too.

Amen. if you air start the fin motors, No RSO would be able to argue the fact that it would get safley airborne on a central 76mm.

However, I think if you choose to make it spin, then putting motors in the outboards might not be a good idea...seems to me having them powered and canted (or beveled or however you want to do it) might put too much undo stress on the assembly. Anyone care to disagree? I kinda hope I'm wrong because it would be super cool, but I think you'd have to chose between one or the other.

 

[susblas]

AWSOME ROCKET! Can't wait to see launch pic's or vid. I agree with everybody it would be safe to use CTI.

 

[metalwizard]

one other suggestion, carbon fiber those fins!! anything large will put some stress on those things, a missfire would be a little scarry, a schread would be...... almost dangerous.

i would rso it as long as the fins are strong and well attached. they really arent out too far to cause a major vector if they dont light.

good luck and keep us informed!!

 

[KermieD]

Originally posted by Loopy
Wow - cool looking rocket! Kermie would be proud...and might recommend stainless steel...(ask him what I'm talking about).

I don't think you'd find too many RSO's that would allow you to light those outboards on the ground. If they're going to hold motors, light them in the air. Question is, how are you going to get the igniter wires to them?

I saw that!!

Loopy is referring to my L2 attempt that had forward swept fins that shredded at maxQ.

I'm not sure what you had in line for motors, but make sure you both a) glass the snot out of those fins. I would actually suggest laminating with different materials (i.e. a layer of carbon, a layer of kevlar, then a layer of glass) to help compensate for resonance frequencies on the flutter and b) make sure you keep the speed well below mach 1. I say well below because, interestingly enough, at higher speeds, forward swept wings are more aerodynamically efficient than sim software allows for. My rocket simmed at about .87 mach, but alt data indicates that it busted mach1. Also, forward swept wings are also *far* more susceptible to flutter at speed.

Also, you want to create a curved connection betwen the leading edge of the fin and the BT. A sharp angle at that connection point will cause the destructive forces of any kind of flutter to focus on one point, where a curve at that area will distribute the forces a bit.

Also, I would suggest running the ignition wires through the front of the fins instead of the rear, as that still follows standard airfoil shapes. You really want airflow to be as clean as humanly possible with this design.

 

[daveyfire]

Just FWIW...

the "expanded outboards" on the tips of the fins is WAY COOL. Paul Sutchek did it a few years ago at BALLS with all red motors... center Wimpy K970 and four wimpy 29mm Hs, with four AT H210Rs on the fin tips. He took off on all the center motors and airstarted the motors on the fins shortly after the rocket left the rail.

It was awesome to watch. This with 38mms should be even better.

Go for it Gunny!

 

[rocwizard]

Paul flew it again on cert motors. lighting 4 J350s in the outer pods on the ground, then lighting a K700, and then 4 H180s

See pic.

 

[gregzo]

Originally posted by rocwizard
4 J350s in the outer pods on the ground, then lighting a K700, and then 4 H180s

See pic.

WOW !!!!

Great photo. I would love to see more pics and especially a video if anyone has one???

 

[karatekicker271]

Originally posted by marvSRG
Awesome! Just do it, man...as DPatell said, I've seen riskier flights

You've seen? All the ones I have seen are made by... you! JUst kidding-
Very Very cool rocket. I am a little late here, but its a very cool design

 

[Ray Dunakin]

Originally posted by rocwizard
Paul flew it again on cert motors. lighting 4 J350s in the outer pods on the ground, then lighting a K700, and then 4 H180s

See pic.

Wow, great pic!! Is that at Jean dry lake?

 

[Gunny]

Here’s a pic of the fin can tacked together with 5 min. epoxy.

 

[Gunny]

The largest outbds I plan to use are J570's... so some reinforcing may be required?

 

[Nate]

I think a little reinforcing wouldn't be a bad idea. Also, make sure your fillets are super strong, especially down at the bottom of the fin. the way the fins are swept forward like that it's going to be pulling hardest on that part of the joint.

 

[Gunny]

Pics of the fin can reinforced with some fiberglass and Kevlar fabric using West Systems Epoxy.

On the fins I used (2) layers of 6 oz, then (1) layer of 3 oz, and (1) final layer of 4 oz glass. I wanted to have a nice veil.

 

[Gunny]

For the motor mount and centering ring to fin attachment points I used (2) layers of 9 oz Kevlar.

I’d like to got some opinions… do you fine folks think this is sufficient or more like way over-kill?

 

[Gunny]

Beautiful day for sanding fins… it’s been 70-75° all week, SWEET!

Tomorrow it’s blackeye peas, collard greens, fat back, and cornbread… oh ya babe!

Happy New Year everybody.

 

[Nate]

Originally posted by Gunny

I’d like to got some opinions… do you fine folks think this is sufficient or more like way over-kill?

Hmmm....I vote that should probably hold it.

Just make sure you launch it on the 4th of July so you have an excuse if it doesn't...you can just claim it was fireworks!

 

[jraice]

NICE JOB!!! You did a very neat looking job (even though nobody see's it on the field) with the kevlar on the motor mount and fin tabs. I cant wait to hear about this one!

 

[quickburst]

Originally posted by Gunny
I have already put a nice chamfer on the leading and trailing edges using a 22.5° router bit.

Would you mind posting the details on this? I'd like to see how it's done. I have a router but have no idea how you are doing this.

Please share.

 

[Gunny]

I use a router table to do the chamfers. The wood is routed on end, not laid flat.

First I run scrap pieces of wood through to fine-tune the bit height and the fence distance in order to get the desired flat width at the tip… then go for it.

The pic is of one of the test pieces propped up against the chamfer bit. I wanted just under 1/8th inch flat at the tip.

 

[Adam Selene]

makes me wish i hadn't sold my router table!

to unhijack the thread: VERY cool looking rocket! Do you plan on launching it anywhere out east?

 

[metalwizard]

Originally posted by Gunny
For the motor mount and centering ring to fin attachment points I used (2) layers of 9 oz Kevlar.

I’d like to got some opinions… do you fine folks think this is sufficient or more like way over-kill?

you can never over build. but you can under power.

 

[RalliART]

That thing looks cool.

I can't wait to see that fly.

 

[Nate]

I miss the trident!!!! it's been over 3 weeks since the last post here.

Any progress? my life isn't complete without this fantastic rocket....