Concrete Form Tube Mid-Power?

Onebadhawk
madcow rocketry
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scsager said:
You may already be aware that a rocket with a "lift-off-weight" of more than 1500 grams is considered "high-power" and requires the flyer to be HPR certified REGARDLESS of the size of the motor.

I'm doubtful you could lift an 8" tube with a single G80 motor. If you build a single motor tube, and without a cert, you are limited to just one G80 motor as the most powerful... You can fly a rocket with a "cluster" of TWO G80 motors to provide the maximum power. This is still allowable without certification.

Two G80's weigh about 260 grams, leaving you 1240 grams for the rocket and recovery gear. The questions now becomes... Can you build a rocket with an 8" concrete form tube that weighs no more than 1500 grams ready to fly???
:cool:

The attached pdf should help show where HPR cert is needed.
Click to expand...

I know that now. I did not realize that however at the start of the project. So here's my official plan : Build one short and fat rocket (perhaps a large scale Big Daddy) that meets MPR criteria. I will use the 29mm mount and retainer I have left over from my 38mm Argent. Then I will use the remaining tube and plywood to create a larger rocket that will be standing by for after I've completed my L1, and will make a good static model in the meantime...

Josh
 
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Sounds like a plan! I temporarily forgot about the weight limit (I have the cert and the field, so I tend not to worry about that) and agree that a concrete form rocket will be near impossible to make under that. Another good reason to not rely on clustered G's!

An 8" Fat Boy would be a great idea :)
 
I need Big Daddy dimensions... I already figured on a 260% increase in size. Anyone have the Big Daddy info or know where to find it?
 
joshismycaptain said:
Choose your own adventure! Love it!

I think I'll just put the 38 in it, attempt to launch on a MP once, and keep it around for a possible HP launch, but mainly comic relief... :D

Josh
Click to expand...

iffen ya use a 38mmt, some time during construction you might say," that's pretty small in there."
personally id use a 54mmt. an adapter is always available to go down to 38mm
im wonderin iffen anyone built an 8" rocket and said," I shoulda put a smaller mmt in there."
 
My 8" sonotube rocket has a 3" host mount. I went to 3" back when I hadn't even flown my L1 rocket. I soon realized that it was overkill as it wouldn't handle that size motor. I didn't care much cuz I could build a 54mm mount. As it turned out, I never have. So, yes, the 38mm hole is small...but is all I ever wanted.

However, your point about adapting down is so true Always go with the biggest you would ever want. :D
 
rstaff3 said:
I love mailing tubes too, but haven't found 8" ones.
Click to expand...

https://www.uline.com/BL_3704/Jumbo-Kraft-Tubes

Problem is, you have to buy them in carton quantities. :rant: But wait! Why not construct your own body tube with a central stuffer tube and additional balsa centering rings and longitudinal spars like a model airplane structure? It would be a lot of work but could be made strong yet light enough to handle mid power engines and be would be an interesting challenge.
 
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rstaff3 said:
Ack I focussed on the tube link. I have built a couple of 8" dia rockets with rings and skins. Low tech stuff, but they worked. 8" x 6' on a G80, what's not to like. And inexpensive to boot.
Click to expand...

You successfully launched an 8"x6' rocket on a G80?
What type of material?
We need a poll here or something.

WHAT IS THE BIGGEST ROCKET SIZE TO MOTOR RATIO YOU HAVE SUCCESSFULLY LAUNCHED???
 
joshismycaptain said:
You successfully launched an 8"x6' rocket on a G80?
What type of material?
We need a poll here or something.

WHAT IS THE BIGGEST ROCKET SIZE TO MOTOR RATIO YOU HAVE SUCCESSFULLY LAUNCHED???
Click to expand...

Here is a post about the two versions. https://rocketdungeon.blogspot.com/2010/12/review-grand-whazoo.html

The original barely was MPR legal. After it was rebuilt, it was a tad over and generally flew on small H's. You can see that, even with just paper and foamboard, weight can be an issue.
 
Years ago had the same idea, a wider diameter rocket on mid power.
The goal was to see how big I could go on a lower power motor...outboard air starts an option.

I built an 8.5 " diameter Apollo Little Joe II with the intention of doing a first flight as a mid power on a G80.
I wanted the large wide diameter with some length to it - but for a nice size "scale" project.

But here's where we differ.
I knew it would have to be VERY lightweight.
I would NEVER have used a sonotube for the airframe.
Way over kill and too much weight penalty.

Instead of using sonotube as the airframe, I rolled poster board around it as mandrel, and the rest of it was all foam core, with the main structural element the internal core main motor mount tube with recovery harness attached to that.
I also made built up fins attached to plywood brackets with through the wall to the main motor tube, with 1/64th ply skins on the outside.

It came in under 3.5 lbs...and it flew and recovered on a G80 - but never again!
It was a nail biter.
As you can see from the pictures, the G80 flight was realistically low and slow...really neat...but recovery was a gut check when the motor burned out.
A good parachute packing job got everything out quickly.

I've got 12 flights on it now, using various H motors with altered (shortened delays) in order to get that main out at apogee.
Won't be doing a G80 again- since it is a proven flyer and holds together on H's.

Good Luck.

_LLS9980.jpg

Apollo Little Joe II.jpg
 
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MaxQ said:
I built an 8.5 " diameter Apollo Little Joe II with the intention of doing a first flight as a mid power on a G80.
I wanted the large wide diameter with the relative length but for a nice size scale project.
But here's where we differ.

I would NEVER have used a sonotube for the airframe.
Way over kill and too much weight penalty.

I rolled poster board around it as mandrel, and the rest of it was all foam core, the main structural element was the internal core main motor mount with recovery harness attached to that.
I also made built up fins, with 1/64th ply skins attached to plywood brackets with through the wall to the main motor tube.

It came in under 3.5 lbs...and it flew and recovered on a G80 - but never again!
It was a nail biter.

I've got 12 flights on it now , using various H motors with altered (shortened delays) in order to get that main out at apogee.
Won't be doing G80s - since it is a proven flyer and holds together on H's.

Good Luck.
Click to expand...

:point::point::point::point: (this was s'posed to be complimentary)
 
rstaff3 said:
Yes, it was him.
Click to expand...

...think that was Small Balls - 2000 at Whitakers NC.
Flew great, wouldn't win a beauty contest but who cares.

I was wondering if the nuts and bolts one stayed together...I recall one at Red Glare that took off the rail, and didn't fare so well.
 
MaxQ said:
...think that was Small Balls - 2000 at Whitakers NC.
Flew great, wouldn't win a beauty contest but who cares.

I was wondering if the nuts and bolts one stayed together...I recall one at Red Glare that took off the rail, and didn't fare so well.
Click to expand...

Yes, you are right about Small Balls @ Whitakers in 2000. Here is a photo of the screw together. Check out those old school 1" lugs. I forget how it fared, it was an EX motor IIRC. It had flown before.

Joe May screw together n power.jpg
 
rstaff3 said:
Yes, you are right about Small Balls @ Whitakers in 2000. Here is a photo of the screw together. Check out those old school 1" lugs. I forget how it fared, it was an EX motor IIRC. It had flown before.

View attachment 304527
Click to expand...
LOL...those lugs...great.

Not sure if this was the same one...but I was standing at Ken's truck when we heard a boom followed by what sounded like someone dropping a big box of nuts and bolts on a concrete floor.
I believe Ken said it was the big rocket bolted together (Fred Wallace?).

I recall Dave's "Redemptive Power"....made from salvage parts from construction sites - built in one week.
140 lb. on an Ex N motor / Jim Mitchell blue formula....or something like that.

Add that to the "Where are they now"?
Dave Bullis .jpg[
 
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MaxQ said:
LOL...those lugs...great.

Not sure if this was the same one...but I was standing at Ken's truck when we heard a boom followed by what sounded like someone dropping a big box of nuts and bolts on a concrete floor.
I believe Ken said it was the big rocket bolted together (Fred Wallace?).

I recall Dave's "Redemptive Power"....made from salvage parts from construction sites - built in one week.
140 lb. on an Ex N motor / Jim Mitchell blue formula....or something like that.

Add that to the "Where are they now"?
Click to expand...

This photo is from Feb 2002 at our old Rhodesdale site.
 

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