TRF Summer Build Off: the "Maximilian"

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Cabernut

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I give you the SB-V1!

The "SB" stands for Summer Build and also for Side Booster. I guess it's a code name for now until I think of something better.

Update: the rocket's name will be "Maximilian"

The only way I could draw up what I had in mind is through RockSim since it supports functioning side boosters that separate.

Here is the first draft:

top_view.JPG

Here is the back view:
back_view.JPG
And the .rkt file
View attachment summer_build_v1.rkt

I only have the trial version of RockSim so it only sims to apogee. Seems pretty good. Apogee is nearly 2000 ft.

All three engines will be ignited at lifoff, the F15 burns for 3.45s and during this time, the D12s in the side will burn and eject the pods - I hope. What I'm not sure of is how well a D12-0 will do at ejecting the nose cone and streamer while under boost from the F15 - since it doesn't have an ejection charge per se. A D12-3 would work better but it's an extra 3 seconds of drag.

As far as the booster attachment / detachment mechanism, I was thinking of using slots/tabs which hold vertically but will slide out as if "peeled back" in the same manner that real side boosters do on real rockets. They will be held horizontally by a cord which will be burnt/cut by the motors at burnout.
 
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neil_w

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Sounds cool. Will the boosters have streamers or something?
 

KenECoyote

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...in the same manner that real side boosters do on real rockets. They will be held horizontally by a cord which will be burnt/cut by the motors at burnout.
That's cool! Has that been done before? I'm asking since I haven't heard of this and think it's a great idea (note I don't have any exp with falling side boosters).

Wow, this is one epic Summer Build-off Competition! :pop:
 

Cabernut

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The side boosters will have either streamers or a small chute.

I think the concept has been done a couple times that I know of with varying degrees of complexity. For this one, I'm just going to try and keep it as simple as possible.

I also need to find a way to take it a bit further from the 4fnc mold. Perhaps sci-fi it a bit. If only there was a BT-80 version of the Interceptor-E nose cone. Now that would be cool.
 

neil_w

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The side boosters will have either streamers or a small chute.

I think the concept has been done a couple times that I know of with varying degrees of complexity. For this one, I'm just going to try and keep it as simple as possible.
I recall reading about this sort of thing before, I think it proved pretty challenging to get to work reliably.

I also need to find a way to take it a bit further from the 4fnc mold. Perhaps sci-fi it a bit. If only there was a BT-80 version of the Interceptor-E nose cone. Now that would be cool.
Well, canopies can be added to regular old nose cones. I've seen some beauties (in pictures at least). Hey, you could also cant the boosters outwards, which would be kind of nuts, but I've had canted clusters on the brain lately so I can't help it. That would make a hell of a 3-way smoke trail. Note to self: look into this.

I think you'll have a pretty good success, and a really nifty launch, if you can just get those boosters to work correctly.
 

Cabernut

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Scratch the idea of using -0 motors in the side pods. Doing so would violate the safety code as, even though they may work, it's not the motor's intended use.

Best choice then would be something with a quick burn and short delay. Less than 3.45 sec would be ideal. There's a B6-2, which would burn and eject in under 3 sec. I would like a bit more kick than a B though.
 

dhbarr

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Clustered side pods, yay! :)
 

Amsterdam

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Pretty dumb of me, since I'm in the contest, to help you kick my ass.:wink:
lol it's not all about winning!

Might be more trouble than it's worth but what about clustered A10s in the pods? They burn real quick and are light weight
 

Cabernut

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Interesting read. Pretty cool. I'm going to save that article and maybe try it some other time. In the article, the side boosters are held on with vertical dowels and use rear-eject to separate and then fall straight back. For this build though, I'm pretty much set on having them pivot back before falling away.

While on lunch, I brainstormed about what I want them to do, and how do I get them to do that. This is a quick MS-Paint sketch of the holding mechanism at the base of the rocket.

Capture.JPG

Main body on the left, booster on the right. The tan parts are balsa/basswood, the brown is the booster motor.

A small square dowel with a rounded end extends out from the booster which holds it vertically while upright.
When the booster is released by burn-through of string or elastic attached higher up, aerodynamic forces will push down on the booster, pivoting it outward where it can slide out.

I'll have to make a physical mock-up to get a hands-on feel for how well this might work.
 

Daddyisabar

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Check out the featured article in this Apogee newsletter by Annette Sostarich.
Pretty dumb of me, since I'm in the contest, to help you kick my ass.:wink:
You hit the nail on the head! With all the craziness this "contest" is not at all about winning, in fact, winning should be the farthest thing in your mind. It is all about building, flying and just surviving your twisted and dreamed up design, expanding your horizons and having fun. Maybe it could show the way for NAR contest flying to improve at the local level, but that is a different subject. This is not the NFL, just have fun Baby! Sorry to Al Davis and Raiders fans on that last line.:wink:
 

grapetang

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Neat design! Isn't it OK to use -0 booster motors in side pods? Seems like it should be fine in regards to the safety code.

Re: holding mechanism: You might want to shorten the dowel so it can pivot freely out of the holding block without catching in the circular recess. It looks like it can catch and get stuck or snap off. An alternative would be to use the typically boost glider pop-pod hook, modified with a rounded hook-end to prevent the same thing from happening.

Would you be able to paint it orange/rust with white side boosters, and add a glider-thingy? :)
 

Flyfalcons

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Scratch the idea of using -0 motors in the side pods. Doing so would violate the safety code as, even though they may work, it's not the motor's intended use.

Best choice then would be something with a quick burn and short delay. Less than 3.45 sec would be ideal. There's a B6-2, which would burn and eject in under 3 sec. I would like a bit more kick than a B though.
Why would it be against the motor's intended use? People have been flying -0's as the only source of propulsion in saucers and other configurations, so obviously it doesn't have to be used only as a booster on a multi-stage rocket.
 

Cabernut

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Why would it be against the motor's intended use? People have been flying -0's as the only source of propulsion in saucers and other configurations, so obviously it doesn't have to be used only as a booster on a multi-stage rocket.
Hmm, well I've read threads on this forum about using -0 motors to eject a recovery system at burnout and that was the eventual conclusion. Using them for ejecting at burnout rather than igniting a sustainer motor could be "purposes other than recommended by the manufacturer". :confused2:

Maybe I'll ask the RSO at the next club launch and see what he says.

BTW, I'm not worried about the "win" aspect of the contest either, I'm loving just participating and I'll help others if I can. Perfect way to encourage some really cool designs and creativity! The Scratch Built forum is goin nuts and it's great! :clap:
 

Flyfalcons

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Come to think of it, my Estes CATO uses a -0 motor to turn the whole thing into confetti upon burnout. I'd say you're well within the proper use of the motor.
 

jqavins

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While on lunch, I brainstormed about what I want them to do, and how do I get them to do that. This is a quick MS-Paint sketch of the holding mechanism at the base of the rocket.

View attachment 292911

Main body on the left, booster on the right. The tan parts are balsa/basswood, the brown is the booster motor.
I take it the holder is inside the main body, with that slightly off white bit between it and the booster being the main body's tube? Looks very nice.

What will be burned through for release? I'm picturing a bit of string, anchored to the main tube and into the booster tube through a hole in the side, and a small button or something inside; is that the idea, or something smarter?
 

Cabernut

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For the string, Im thinking maybe just that, a string. Strong enough to hold the boosters horizontally, running as one piece through the main body. So when the first side breaks, the other side is also free and they go together.
In theory...
 

dhbarr

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Yup, burn thread. Apogee heliroc and cirrus both use it, plain ol' thin thread.
 

Cabernut

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So I built a prototype / mock up of the release mechanism with a little more breathing room - worked half the time. Held in solid while upright, but half the time it would bind at about 30-40 deg from vertical.

This gave me a few ideas of how to improve. Smaller / narrower and won't bind if it leans a bit to the side.

What I'm thinking for ver 2 is: at the bottom of the booster there will be a small half-hinge that will hold it from moving downward and horizontally(we don't want them to swing outward under thrust). Then up higher there will be a slot-and-tab to hold the booster from moving upward. When the booster tilts away, the tab is released and then is free to pivot back and away

I must say, this is really exercising my mind-sim. I'm enjoying having to really think about how something is going to work.
 

Cabernut

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It needed a name and it hit me today - along with some design inspiration.

One of the coolest sci-fi robots ever:



Maximilian!

So that lead me to modify the design a bit:

View attachment summer_build_v3.rkt

top_view_v3.JPG

back_view_v3.JPG
 
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Cabernut

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With the new inspiration in mind, I worked on the sci-fi aspects a bit more. What kind of ship would Maximilian have if he flew his own ship?

For the cockpit, It will resemble Maximilian's devilish red eye...

color_view_v4.JPG
top_view_v4.JPG

View attachment summer_build_v4.rkt
 

neil_w

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Looking awesome. I'm digging forward-swept fins (especially canards) these days, so that hits the sweet spot perfectly.
 

Cabernut

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Some parts are on the way. A BT-80 9" ogive nose cone and an extra long 29mm motor mount with plywood centering rings. I should have everything else on hand. But before I start cutting basswood, I need to know if my revised design for the booster separation mechanism works.

This one works. Works really well. At least from the mock-up that I've built to test the idea that is.

This is a crude mock-up made from scrap parts, but the basic function will be the same for the final product.
On the booster, there will be a small hook at the bottom for the pivot point and a tab on the side which will hold it in place as long as it's held parallel to the main body tube. Inside the main airframe will be a slot that will hold the tab from the booster, above which the burn thread will pass through.




A small piece of wood will support the hook instead of just the tube wall.




The burn thread will just be taped firmly to the side like so




Here is a hard-to-get interior shot of the booster showing the thread passing about 2" above the top of the motor.




I tested this by (don't try this at home kids) filling the tube with some butane from a lighter and lighting it to produce a flame so that I could see how fast it burnt and released. It went quick and fell off just as planned.

Here is how it pivots upon burn thread release



A close up shot of the pivot point just before falling away.




This also gave me the idea that I could use alternate sizes for the boosters as well. One set for 18mm motors and another set for 24mm, totally interchangeable.

Next step is to draw up real measurements for all of the little parts needed.
 

dhbarr

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This also gave me the idea that I could use alternate sizes for the boosters as well. One set for 18mm motors and another set for 24mm, totally interchangeable.
29mm long burns, you say? :-D
 

Cabernut

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29mm long burns, you say? :-D
An Estes F15 for starters, 3.45s burn. Long enough. Then there's the Apogee F10, but I can't get those here. Which reminds me, that's a benefit of using booster pods. High initial thrust to get off the rod quick, then a gentle long burn to continue the flight.

And for those who happen to have no idea who Maximilian is:

[youtube]KZWttTwPl_Y[/youtube]
 

BABAR

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Suggestion for burn string. Consider elastic. It burns through just as easily and is self tightening. So you don't need to worry as much about it getting loose once you have tied it.
 

Cabernut

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Suggestion for burn string. Consider elastic. It burns through just as easily and is self tightening. So you don't need to worry as much about it getting loose once you have tied it.
You mean like the thin elastic thread of a paddleball?
 

BABAR

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That would work. I use #16 Rubber bands for ascent rotor retention on my helicopters. When stretched they burn through almost instantaneously. They require slightly bigger holes (think notebook paper punch size). I also use a crochet hook during "rigging." I can run it right through the rocket to pull the band from one side through the rocket to the other.
 
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