Level 3 MadCow Super DX3: No Fiberglass, No Carbon Fiber, no sweat ... ?

FerdBerful · Oct 10, 2013

Perhaps a bit premature, but I'm planning to build a kit-bashed MadCow Super DX3 with a 75mm motor tube
with the idea that I might try to get my level 3 with it (not on the first flight)

Almost every experienced rocketeer I've talked to says (paraphrase) "Not sure that's a good idea"

Unfortunately, given my nature, that's just increased my motivation to try it

It started out as a bit of a joke, but as I've thought about it, I get ideas ...

I recently bought some 1/16" walnut veneer with that wacky idea that I would make 5 ply plywood
with it and use it for fins, centering rings, etc.

And then I was talking to someone about the cardboard level 3 and how heavy it might be and
they said that instead of making it heavy I should be thinking about drag (E.g. tube fins, ...)
... But it *has* to be a Super DX3. So ...

I thought, what if I leave off the (outer) airframe for (say) 12" - 18" and have exposed centering rings
and various truss-like "stuff" glued between them? That ought to increase the drag a wee bit.

Anyway, just thought I'd start a thread to document the build (or lack thereof)

cbrarick · Oct 11, 2013

so, how would you connect the body tube to the motor tube if the centering rings are all exposed?

Long before composites and epoxy became the mainstay of our hobby, people did L3s on cardboard rockets built with (gasp) wood glue.

but I got 2 questions....

will your L3CC or TAP approve this? (do you have one, have you written your package)
do you have the waiver to just do it with a regular DX3 and a M?

JMHO

ColumbiaNX01 · Oct 11, 2013

Perhaps a bit premature, but I'm planning to build a kit-bashed MadCow Super DX3 with a 75mm motor tube
with the idea that I might try to get my level 3 with it (not on the first flight)

Almost every experienced rocketeer I've talked to says (paraphrase) "Not sure that's a good idea"

Unfortunately, given my nature, that's just increased my motivation to try it

It started out as a bit of a joke, but as I've thought about it, I get ideas ...

I recently bought some 1/16" walnut veneer with that wacky idea that I would make 5 ply plywood
with it and use it for fins, centering rings, etc.

And then I was talking to someone about the cardboard level 3 and how heavy it might be and
they said that instead of making it heavy I should be thinking about drag (E.g. tube fins, ...)
... But it *has* to be a Super DX3. So ...

I thought, what if I leave off the (outer) airframe for (say) 12" - 18" and have exposed centering rings
and various truss-like "stuff" glued between them? That ought to increase the drag a wee bit.

Anyway, just thought I'd start a thread to document the build (or lack thereof)

This guy seems to be a little out of touch with reality!!
Level 3 certification is not the time to do anything fancy and or crazy. Do what people have done in the past tried and true. Once you get your level 3 cert then start with some fancy stuff.

qquake2k · Oct 11, 2013

You plan on flying it at Snow Ranch? I want to be there for that launch!

chadrog · Oct 11, 2013

I asked this in another thread but was ignored - Doesn't a rocket for a level 3 certification attempt need to be planned out and approved before the building starts? I know it does for a NAR certification, is it different with TRA? Statements like "with the idea that I might try to get my level 3 with it" confuse me.

dixontj93060 · Oct 11, 2013

chadrog said:
I asked this in another thread but was ignored - Doesn't a rocket for a level 3 certification attempt need to be planned out and approved before the building starts?

Yes.

jmight · Oct 11, 2013

andrewlathrop87 said:
This guy seems to be a little out of touch with reality!!
Level 3 certification is not the time to do anything fancy and or crazy. Do what people have done in the past tried and true. Once you get your level 3 cert then start with some fancy stuff.

At the same time, is it not fun to test the limits and push to do something that is unique and original? Assuming it passes muster with respect to safety and structural integrity, why not encourage the pursuit of a fun and quirky project? It seems that people often are quick to jump someone because their ideas differ from the norm, but in my opinion the ability to break that mold is a sign of ingenuity.

chris m · Oct 11, 2013

Do what makes you happy .

CCotner · Oct 11, 2013

andrewlathrop87 said:
This guy seems to be a little out of touch with reality!!
Level 3 certification is not the time to do anything fancy and or crazy. Do what people have done in the past tried and true. Once you get your level 3 cert then start with some fancy stuff.

Not necessarily-Look at Jim Jarvis L3'ing on an N4000BB minimum diameter. =p

Once I'm rich and famous, I (tentatively) plan on L3'ing on a 75mm Minimum Diameter full M, entirely scratchbuilt except for the electronics. =p

CarVac · Oct 11, 2013

CCotner said:
Not necessarily-Look at Jim Jarvis L3'ing on an N4000BB minimum diameter. =p

Once I'm rich and famous, I (tentatively) plan on L3'ing on a 75mm Minimum Diameter full M, entirely scratchbuilt except for the electronics. =p

Of course, you're not gonna build it with wood glue and paper tubes, though.

A cardboard 4" rocket with a 3" motor sounds like a recipe for disaster. Not "Not sure that's a good idea", but a disaster.

Cardboard might be ok with an 8" rocket on an M, but not for this.

REK · Oct 11, 2013

No reinforcements what so ever eh? I like your passion, however with the cardboard tubes I too think they can shatter from such a stressful flight without any glass. My advice to you is replacing the tubes with either phenolic or the almight Blue Tube. That way you dont have to worry about reinforcing anything with glass or carbon.

DizWolf · Oct 11, 2013

I said I'd never go for L3. Then I promised I'd wait a year after my L2 before I even started planning L3. That lasted about the car ride home... So I've just started poking around for ideas and planning things. An M is a hell of a lot of motor. Which is why I don't quite understand why L3 is where a lot of people take a minimalist approach. Don't get me wrong, it's your rocket, and should be what makes you happy. But the fiberglass Super DX3 kit is right there, all set to go with a 75mm mount and has a much higher chance of survival. On an M1500G a stock cardboard DX3 is going to go around 1400 mph and 14K feet if it survives. Rocksim puts that at mach 1.8. that's a lot for cardboard to take. Then again if you ran the mmt almost to the top and reinforced the inside like crazy the booster may take it, but I'd worry about folding the payload. I haven't been there, so I'm just thinking out loud.

gldknght · Oct 12, 2013

I agree with DizWolf and the others, do what makes you happy, but do it safely. Fiberglass reinforcement is not completely necessary for a L3 project if it's constructed from appropriate materials, but your certification flights at any level are not the best times for experimentation with unusual or untried designs.

FerdBerful, what's your current cert level? Why not build a "scaled down" model of what you intend for your cert flight and see how it performs on smaller motors? You'll have fun learning without the huge risk of an M powered experimental design.

Sailorbill · Oct 12, 2013

gldknght said:
I agree with DizWolf and the others, do what makes you happy, but do it safely. Fiberglass reinforcement is not completely necessary for a L3 project if it's constructed from appropriate materials, but your certification flights at any level are not the best times for experimentation with unusual or untried designs.

FerdBerful, what's your current cert level? Why not build a "scaled down" model of what you intend for your cert flight and see how it performs on smaller motors? You'll have fun learning without the huge risk of an M powered experimental design.

I agree on the "proof of concept" route if you are using something different for a cert flight. If you can prove to your L-1, 2 or 3 cert folks that the design works they should be more likely to approve it.

UPscaler · Oct 12, 2013

andrewlathrop87 said:
This guy seems to be a little out of touch with reality!!
Level 3 certification is not the time to do anything fancy and or crazy. Do what people have done in the past tried and true. Once you get your level 3 cert then start with some fancy stuff.

Cardboard L3 rockets aren't crazy stuff. I would fly a 4" cardboard and wood glue rocket on an M. Not a high thrust one, but these rockets can take more than people seem to think. A long nice long burning M would likely make for a sweet flight.

Braden

Aksrockets · Oct 12, 2013

gldknght said:
FerdBerful, what's your current cert level? Why not build a "scaled down" model of what you intend for your cert flight and see how it performs on smaller motors? You'll have fun learning without the huge risk of an M powered experimental design.

A downscaled DX3 (lets say a 3in with a 54) will not go through the same stress that the 4in with a 75 will.

Ferd,
Read through this thread:
https://www.rocketryforum.com/showt...sible-LOC-Magnum-quot-Price-of-Admission-quot
A 5in rocket with a M650 did not end well.

Alex

tuxxi · Oct 12, 2013

[video=youtube;ijxpg5iqTjs]https://www.youtube.com/watch?v=ijxpg5iqTjs[/video]
Minimum Diameter M650W rocket. Mach 1.5. No FG of CF according to the uploader. Cardboard is great stuff. I've flown straight cardboard to ~Mach 1.5 time and again.

gldknght · Oct 12, 2013

Aksrockets said:
A downscaled DX3 (lets say a 3in with a 54) will not go through the same stress that the 4in with a 75 will.

Ferd,
Read through this thread:
https://www.rocketryforum.com/showt...sible-LOC-Magnum-quot-Price-of-Admission-quot
A 5in rocket with a M650 did not end well.

Alex

I'm not sure I agree with your analysis. The rocket in that thread had a catastrophic fin failure due to unreinforced ply fins going through transonic shock waves. It was not the result of too much motor.

I'm sure there are several hard hitting 54 mm motors out there that will send a 3 inch rocket supersonic.

jmight · Oct 12, 2013

Alex is still right that that is not a direct comparison. Forces can't be assumed as scale-able between a smaller model and the real thing. When a company building a rocket or something similar builds a small scale model, they are generally putting it in a wind tunnel under very controlled conditions and making comparisons using dynamic similarity. (Relations between Reynolds Numbers, and the various aerodynamic coefficients that the model will undergo.)

CarVac · Oct 12, 2013

gldknght said:
I'm not sure I agree with your analysis. The rocket in that thread had a catastrophic fin failure due to unreinforced ply fins going through transonic shock waves. It was not the result of too much motor.

I'm sure there are several hard hitting 54 mm motors out there that will send a 3 inch rocket supersonic.

Of course, but stresses scale differently.

troj · Oct 13, 2013

SinfulDarkLord said:
No reinforcements what so ever eh? I like your passion, however with the cardboard tubes I too think they can shatter from such a stressful flight without any glass. My advice to you is replacing the tubes with either phenolic or the almight Blue Tube. That way you dont have to worry about reinforcing anything with glass or carbon.

Cardboard can "shatter"?! Only if you chill it down way below freezing, first! Cardboard might crumple, it might tear, but it certainly won't shatter.

Phenolic, on the other hand, shatters quite nicely. Even when reinforced with fiberglass -- whack it hard enough and the fiberglass stays intact, while the phenolic inside shatters. Learned that the hard way!

There is absolutely nothing wrong with a Level 3 rocket built from cardboard and wood. We've launched a Q motor where the entire structure was cardboard and wood, and held together with Titebond II.

andrewlathrop87 said:
This guy seems to be a little out of touch with reality!!
Level 3 certification is not the time to do anything fancy and or crazy. Do what people have done in the past tried and true. Once you get your level 3 cert then start with some fancy stuff.

Ugh. KISS. Boring

Going the "safe" route on a certification flight is the epitome of boring, to some. Fly what makes you happy.

If you want to try something different, work up to it, first -- for example, don't make Level 3 your first extreme flight. Don't make it your first flight of an all cardboard rocket.

But don't believe that you have to fly a 6" diameter all fiberglass rocket, either....

-Kevin

cwbullet · Oct 13, 2013

Pass the popcorn, this should be interesting.

FerdBerful · Oct 14, 2013

RE: how to attach the body tube

I have a 36" motor tube. My plan is to only have (say) 24" exposed with 12" inside the airframe tube. My plan is to use 8" couplers
epoxied inside the full length of the body tube so the centering rings/reinforcing struts would be inside this double layer.

RE: L3CC/TAP not there yet. My plan is to fly it starting with a J or K and if all goes well eventually a full L. If that is successful, it's a tiny
jump to a baby M and level3 .

Aksrockets · Oct 14, 2013

Consider lining the entire BT with a coupler. That'll give you a lot of strenth and doesn't use composites.

Alex

FerdBerful · Oct 14, 2013

RE: start with tried and true:

That's plan B. This just sort'a happened. If you know Myers-Briggs, I'm an INTJ: "Life's independent thinker"
I get a kick out of doing something unusual. A friend of mine got his level 3 using a PVC pipe, tube fin rocket.

FerdBerful · Oct 14, 2013

RE: Snow Ranch:

Probably not any level 3 flight. Given how slow I am at building, next summer at Black Rock might be the "stretch" goal

FerdBerful · Oct 14, 2013

If it's a disaster, I'm committed to it being be a very safe disaster after a series of progressively more powerful motor flights. If (say) the LCO is concerned,
it's certainly an option to launch from (say) a 1000ft pad as a heads up flight.

FerdBerful · Oct 14, 2013

RE: 1/16" x 5 plywood (fins)

I left out that I plan to double up the 5/16" plywood to 10/16" for the fins. (aka 5/8" or ~ 16mm)

These should be *really* stiff. Perhaps even stiff enough for transonic
(which may not occur if the rocket is "draggy" enough.)

FerdBerful · Nov 11, 2013

Some photos:

120LBS homemade plywood press:
https://lh4.googleusercontent.com/-...YQC5C5qsM/w544-h799-no/walnutPlywoodPress.png

Homemade five ply solid walnut plywood. Created with 1/16" walnut veneer. Sheet is ~ 12" x 24":
https://lh4.googleusercontent.com/-...LgXZ88/w742-h390-no/walnutPlywoodOnTblSaw.png

Close(er) up of walnut plywood:
https://lh6.googleusercontent.com/-...AMI/PZr2395Cvs0/w742-h507-no/walnutPlyEnd.png

The epoxy soaked through around knots and such:
https://lh3.googleusercontent.com/-...aLh0jugPs/w742-h575-no/walnutPlyEpoxySoak.png

FerdBerful · Nov 27, 2013

Updates:

- I've come up with a name for my new rocket:

Leapy McWonder Woody

- I'm making a single throw double poll screw switch for the rocket:

Part for my home-made screw switch

Part for my home-made screw switch (2)

- I've cut out the fin blanks:

Home-made walnut plywood fin blanks

Home-made walnut plywood fin blanks (2)

Level 3 MadCow Super DX3: No Fiberglass, No Carbon Fiber, no sweat ... ?

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