Body Tube Diameters

[samb]

Thank you for the post. Very interesting article. What year was it written? 2018?

2006 or 2007.

 

[steveh.jae]

Simple answer: It doesn't. The BT numbering is fundamentally arbitrary, although there is logic in it here and there. For example, a BT-60 can fit three BT-20s in a cluster. Higher numbers mean larger.

So, in general, don't try to look for significance in the numbers. Know the important facts, like BT-5, BT-20, and BT-50 are motor mount tubes for 13mm, 18mm, and 24mm motors, respectively. Committing diameters of the most frequently-used sizes to memory is also pretty useful when scratch-building.

And when in doubt, go to a reference table, such as https://www.ninfinger.org/rockets/body_tubes.html or https://www.erockets.biz/body-tube-sizes/.

Thnx 4 the links

 

[Rocks&Rockets]

"Sometimes you have to conform to a long established standard, no matter how illogical it is."
[/QUOTE]
Read as- Imperial feet & inches.
Learn METRICS! Simple and Logical

 

[Ez2cDave]

Read as- Imperial feet & inches.
Learn METRICS! Simple and Logical

Sorry, "forced conformity" is not in the vocabulary of true Americans !

Dave F.

 

[kuririn]

Learn METRICS! Simple and Logical

Agreed! I remember when liters instead of gallons started showing up on gas pumps in the US.
Guess where the Great Metric Conversion winded up. In the dump heap.
People like what they are used to, even if it is illogical.

 

[Ez2cDave]

Agreed! I remember when liters instead of gallons started showing up on gas pumps in the US.
Guess where the Great Metric Conversion winded up. In the dump heap.
People like what they are used to, even if it is illogical.

One man's "illogic" is another man's "normalcy" . . . The real "illogic" is demanding "conformity" !

Dave F.

 

[steveh.jae]

Agreed! I remember when liters instead of gallons started showing up on gas pumps in the US.
Guess where the Great Metric Conversion winded up. In the dump heap.
People like what they are used to, even if it is illogical.

So, so dispiriting. WTF!!!???

how many inches in a mile?
how many meters in a kilometer?

Base 10. People!

please Base 10
(remember/forget) JPL v. JSC

History will TRULY judge us as dentitionaly challenged if we can’t recognize this for what it is, a full-on coup-de-etat

 

[RoyAtl]

How does Estes do it's body tube nomenclature? BT-50 that's about 1 inch.
How does 50 relate to an inch!?

Initially Estes had two body tube sizes. BT-1, which was the tube for the Model Missiles Aerobee and Arcon. Surplus stock from them. BT-3 was a tube initially hand-rolled by Gleda Estes (on the kitchen floor!) that they used on the Astron Scout and other early kits (SkyHook, WAC Corporal). later on, Bill Simon found Euclid, and Estes started using those tubes while also selling the earlier tubes. So that initial line up was:
BT-10 The mylar tube for the Astron Streak .720 od
BT-20 The new standard minimum diameter tube. .736 od
BT-30 The new name for BT-3. .765 od
BT-40 The new name for BT-1 .825 od
BT-50 new tube .976 od
BT-60 new tube 1.637 od

And so for that brief time, the system was sorta logical. And as he said in that article, new diameters would get assigned numbers in-between those!

BT-5 smaller than BT-10
BT-55 in-between 50 and 60
PST-65, plastic payload tube a little larger than 60
BT-70 body for Gemini Titan 3, and ring tubes for Astron Sprite and Starlight.

But then they got into weird tube sizes for scale models!
BT-51 (because BT-50 didn't quite work for the Saturn 1 model)
BT-52 for the Thor Agena (later used on Battlestar Galactica rockets)

More sizes for the Saturn IB and V
BT-3 for the Saturn IB's apollo escape tower
BT-58 for Apollo Saturn V CSM
BT-63 for Saturn IB internal ("Juno II" tank diameter to cluster the "Redstone" BT-51s) and Saturn V replaceable motor mount (mount made of BT-60 could slip fit into it!)
BT-80 for Apollo Saturn V SIV-B stage
BT-100 for Saturn IB SIV-B stage (later also Mars Lander and initial R2D2)
BT-101 for Saturn IB engine section and Saturn V main body.

When they started using a couple of Centuri's tubes, they stuck weird numbers on them too.
ST-13 became BT-56 -- the workhorse tube for Astrocam 110, and many of their initial china-made starter kits.
ST-20 became BT-68 -- Space Shuttle main tank, Jupiter C, later Mercury Redstone.
ST-8 was used for Space Shuttle SRBs but I don't think a BT number was assigned, just a computer stock number.

 

[jimzcatz]

estes bt70 is 2 inches

 

[Ez2cDave]

estes bt70 is 2 inches

Sorry, Jim . . . BT-70 is 2.217" .

Dave F.

 

[Ez2cDave]

Go "Old School" . . . a 1/64 Ruler !

 

[tab28682]

estes bt70 is 2 inches

?? BT-70 is 2.217" OD and 2.175" ID.