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337% Big Daddy - "Midnight Express" - L3 cert project

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delta22

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LDRS is coming back to NY for 2012 and I'm going for my L3!

Decided to build an upscale Big Daddy because:
> I like the way they look
> Could use 10" diameter parts from Polecat Rocketry for reasonable cost
> Short rocket would fit in my car
> By building relatively light could fly a wide range of motors

Naming it "Midnight Express".

The 337% (or approximately 3.4x) upscale Estes Big Daddy will be 68" tall x 10" diameter, estimated L3 flight weight 33 lbs.

On a ProX 75mm 4grain M1230 Imax, should hit about 3800ft at just over 500mph.

On a ProX 54mm 4grain K740 C-Star, should reach about 1500ft. Love the idea that this is the same propellant used in the Space Shuttle's boosters. A K maxes out my regular CMASS flying field and 1500 feet dual deploy recovers well there.

Thanks to Robert DeHate for providing expert advice and being my L3CC. Thanks also to Sport Rocketry magazine for instituting a policy of paying for feature articles, providing a significant piece of the funding for this project.
 
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delta22

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Primary parts for this project:

Polecat Rocketry 10" fiberglass nose cone, $129. Nicely formed, Gel coated, thin and light for its huge size.

Polecat 10" x 4 ft body tube, $100. 1/8" cardboard covered by what looks like one wrap of 6 oz fiberglass.

3/8" x 2' x 4' sheet of end-grain balsa, $30. Will be covered with carbon fiber to form fins.

Four foot ruler in image for scale. These are BIG parts.

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UPscaler

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This is AWESOME! M1230 is an awesome motor too, I'm sure Eric foster will be here shortly :wink:



I'll be watching this one!

Don't tell me there's only going to be one motor tube in this thing...


:grin:



Braden
 

delta22

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The big Polecat NC is similar in shape to the Big Daddy NC, but not an exact match. First picture shows the 3" BD NC in the foreground and the big NC in the darker background.

Two main differences are the BD NC has a more conical shape at the very tip and Polecat NC is more gradual and stretched at the base.

pic 2: Rounded Polecat NC tip

pic 3: small paper cone with epoxy in tip, later filled with epoxy and glued to big NC

pic 4: Epoxy tip sanded and rounded at the tip, with Bondo filler

Later wrapped NC tip with 6 layer build up of 1.3 oz FG to strengthen.

To deal with the fact that the Polecat NC is proportionally longer at the base, will shorten the body tube the same amount to keep overall rocket correctly proportioned. Instead of scale 30" NC and 34" body, build will have 34" NC and 30" body. Including swept back fins, NC split point will be exactly at middle of rocket.

Body will be dark blue and curvature of NC at base is extremely slight.

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delta22

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The NC is nicely formed and a good price for its huge size.

It is fairly thin and light, at about 4 lbs and 3/64" thickness, I'm guessing a buildup of 30-40 oz of FG.

Wanted to 1) add weight at the front of the rocket for stability and 2) strengthen the NC.

Fiberglassed two layers of 10oz glass to the inside of the NC using Light 12" sleeving from Soller.

Now NC is about 6 lbs and feels stiffer and more solid. Also has the right amount of weight to make my RockSim model stable.

pic 1: improvised tool to sand deep down the inside NC

pic 2: the big FG sleeve, 1 of 2 that went in along with 1+ lb of West 206 resin

pic 3: additional FG in place

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delta22

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This is AWESOME! M1230 is an awesome motor too, I'm sure Eric foster will be here shortly :wink:

I'll be watching this one!

Don't tell me there's only going to be one motor tube in this thing...

:grin:

Braden
Thanks.

Yes, I like the Imax motors too, for their bright white flames and long burns.

There will be one 3" motor tube for the big AP motors .....

....and the bottom centering ring will be recessed 2.5" up from the bottom of the body tube. That way, if I ever have the funds, the rocket can be fired by a pancake of 127 Estes C6 motors!

I didn't mention that up front because I don't know when I will have the opportunity to do this.
 

UPscaler

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Thanks.

Yes, I like the Imax motors too, for their bright white flames and long burns.

There will be one 3" motor tube for the big AP motors .....

....and the bottom centering ring will be recessed 2.5" up from the bottom of the body tube. That way, if I ever have the funds, the rocket can be fired by a pancake of 127 Estes C6 motors!

I didn't mention that up front because I don't know when I will have the opportunity to do this.
OH MY.


I knew there had to be something of that hanging around :wink:



Braden
 

Eric1

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This is AWESOME! M1230 is an awesome motor too, I'm sure Eric foster will be here shortly :wink:



I'll be watching this one!

Don't tell me there's only going to be one motor tube in this thing...


:grin:



Braden

Yep! Here I is!!! Subscribed!!:D
Looking good so far!:cool: The Imax is a most excellent choice!
 

GRIFFIN

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this will be cool. Are you going to make the nose the Av-bay??

I am building a Gizmo XL with 3 motor airstart cluster, so I will be watching this one. Looks good.





Jason
 

eggplant

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It looks great so far! Other than the future "pancake", is there any plan for a cluster?
 

Rocketman248

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If you like the idea of C-Star being the same propellant as the SRBs, take a look at the M2250C-Star. Same case as the M1230. Either way, this will be an awesome project!
 

redsox15

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subscribed. Can't wait to see it at LDRS!!

Matt
 

delta22

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this will be cool. Are you going to make the nose the Av-bay??

I am building a Gizmo XL with 3 motor airstart cluster, so I will be watching this one. Looks good.

Jason
Yes, e-bay will be in base of NC. There will also be a 4" central tube in NC containing main chutes that will have a shear pinned plug at the bottom.

E-bay will wrap around central tube and be closed top and bottom by centering rings. This will allow for 3 e-bay vent holes evenly spaced around the circumference of the rocket placed 1-2" above the split point.

It looks great so far! Other than the future "pancake", is there any plan for a cluster?
Trying to strike a balance between strength and light weight, particularly at the tail of the rocket. So one 3" motor tube and room for BP motor pancake only. Also carbon fiber over end-grain balsa fins - crazy light and strong. Thanks to R. DeHate for advice on this.

With exposed CF fins and dark blue body should look cool. Also vinyl white stars and red flames for the full "Midnight Express" effect.

If you like the idea of C-Star being the same propellant as the SRBs, take a look at the M2250C-Star. Same case as the M1230. Either way, this will be an awesome project!
Thought about the M2250 C-Star, but the 666 lbs peak thrust is more stress than I want to put on this airframe, and the M1230 Imax has a nice bright, white flame and a 4.5 second burn.

subscribed. Can't wait to see it at LDRS!!

Matt
Thanks. I'm looking forward to LDRS too. It will be amazing.
 

Sailorbill

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delta22 said:
Thought about the M2250 C-Star, but the 666 lbs peak thrust is more stress than I want to put on this airframe, and the M1230 Imax has a nice bright, white flame and a 4.5 second burn.


If you want a motor to get it moving and have the room, try theM1300 Imax/Dual Thrust™. 635 lbs of thrust for one second the drops back to 250 lbs for another 3 plus seconds.:D A bird that big needs to get moving fast so the effect of the wind is minimized and the M1300 does that. Then the power throttles back so it doesn't reach the higher speeds that could harm those big fins. I used one in my Ultimate Endeavour in fairly strong winds and it flew like it was on a rail.

Good luck on your flight a friend of mine is buildig a 9" version.
 

JDcluster

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I know of 2 other large upscales of Estes kit planned to be launched this year
both being Fat Boys.


JD
 

delta22

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Catching up on posts for this build:

Created a cardboard template for the fins, which included the large tab.

Cut out oversized fin cores from 3/8" end grain balsa. Sandwiched cores with 2x layers of 6 oz carbon fiber and West 207 epoxy.

Covered each side with release plastic, squeegeed out air bubbles and pressed between sheets of glass.

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delta22

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Cut off excess from fins and sanded edges uniform.

Carefully vacuumed up carbon fiber dust.

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delta22

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Covered each outer fin edge with 2x layers of 6 oz fiberglass and a cap of basswood.

The FG for structural strength and the basswood for additional wear resilience and shape.

Bottom and outer edges got 1/8" basswood cap.

Leading (upper) edge was built up and shaped from 3x layers of 1/8" basswood.

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delta22

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Polecat 10" body tube came with one wrap of medium thick fiberglass. Added two more layers of 1.3 oz FG for uniformity and smoother finish.

Put one layer of 6 oz FG on outside (exposed) surface of engine centering rings.

Installed Ubolt on top CR and 2x 1/4" Tnuts on bottom CR.

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delta22

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First tacked fins in place with CA.

Then adjusted slightly and tacked further with a few spots of fast epoxy.

Then filleted and tied it all together with 2x layers of 6 oz FG, anchoring together motor tube, fins and top and bottom CRs.

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delta22

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Slotted Body tube.

Epoxied fin assembly in place using a generous amount of West 206 epoxy. Included a thrust ring of coupler tube above the top CR for good measure.

2x layers of 6 oz FG inside recessed bottom CR. Is recessed slightly so that someday a pancake of 127x C6 motors might sit there.

Filleted fins to body tube.

While there is plenty more work to do, got things far enough along to see what completed rocket looks like standing next to an Estes Big Daddy.

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gdjsky01

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Polecat 10" body tube came with one wrap of medium thick fiberglass. Added two more layers of 1.3 oz FG for uniformity and smoother finish.
Putting on the light FG for a smoother surface makes good sense. Will you need to still fill in weave? If so, with what if I may ask? Or since the 1.3oz is probably not for strength, will you just sand it smooth (and if some fibers get sanded off, oh well?)

GR8 build so far! :clap: Kind of a "Daddy - Oh!!"
 

delta22

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That thing is going to be bullet proof!
Trying to strike a balance between strength and weight. Strong enough plus a safety margin, to fly just past 400mph on a baby M1230, light enough to fly nicely on a K or even on a mega cluster.

The carbon fiber is sandwiched around end grain balsa, both to reduce weight and to try a new technique. Knocked off about 2 pounds compared to conventional plywood fins. Had hoped to save more weight, but not vacuum bagging reduced benefit.

Robert DeHate, my L3CC advisor, suggested the technique. While I am glad to have done it for this project. Not sure I will take the time and money to do it again.

Very! nicely done B.
Thank you Gary, that means a lot from someone who has built as many cool rockets as you have.

Putting on the light FG for a smoother surface makes good sense. Will you need to still fill in weave? If so, with what if I may ask? Or since the 1.3oz is probably not for strength, will you just sand it smooth (and if some fibers get sanded off, oh well?)
FG that fine has such a fine weave that it would be hard to see even if you painted directly over it.

I always sand FG for epoxy and paint adhesion, quickly removing the slight texture from this glass surface.

A thin final wrap of FG like this is often referred to as a "veil", as it is as thin and translucent as a veil.
 

delta22

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Added 2.1 lbs nose weight to get stability plus a safety margin with all planned motor combinations.

Lead shot plus West 206 epoxy.

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delta22

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In order to fill uneven areas in the wood trim and carbon fiber and just slightly further tie tail together, covered fins tip to tip with 2x layers of 1.3 oz FG.

Later sanded it all smooth and rolled on a very thin top coat of West 207 epoxy with 15% alcohol.

Finally got the mirror finish on the fins that I had been looking for.

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cwbullet

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That is one big daddy.
 
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