What size body tube is this?

[Odo]

Can anyone tell me what size body tube this semroc kit is? It says the body tube diameter is 1.54" (3.9 cm) Im sure that would mean something to one of you, because it certainly doesnt to me Im thinking of getting it and adding modifications but I am a scrub when it comes to body tube sizes.
https://www.semroc.com/Store/scripts/RocketKits.asp?SKU=KS-12

Thanks!

 

[Kehoes23]

Can anyone tell me what size body tube this semroc kit is? It says the body tube diameter is 1.54" (3.9 cm) Im sure that would mean something to one of you, because it certainly doesnt to me Im thinking of getting it and adding modifications but I am a scrub when it comes to body tube sizes.
https://www.semroc.com/Store/scripts/RocketKits.asp?SKU=KS-12

Thanks![/
Not sure what you are asking, are you familiar with millimeters? The motor this kit uses is 18mm.

 

[Odo]

Can anyone tell me what size body tube this semroc kit is? It says the body tube diameter is 1.54" (3.9 cm) Im sure that would mean something to one of you, because it certainly doesnt to me Im thinking of getting it and adding modifications but I am a scrub when it comes to body tube sizes.
https://www.semroc.com/Store/scripts/RocketKits.asp?SKU=KS-12

Thanks![/
Not sure what you are asking, are you familiar with millimeters? The motor this kit uses is 18mm.

I meant like, is the body tube for this kit a bt-50 or bt-60

 

[kruland]

The wonderful thing about Semroc is they have lots of different tubes - weird sizes, thick wall, etc. I suspect they stock this tube. Go here Semroc Body Tubes and see if you find something which matches. Here's a hint, it's not bt-50, 55, or 60

I meant like, is the body tube for this kit a bt-50 or bt-60

 

[Odo]

The wonderful thing about Semroc is they have lots of different tubes - weird sizes, thick wall, etc. I suspect they stock this tube. Go here Semroc Body Tubes and see if you find something which matches. Here's a hint, it's not bt-50, 55, or 60

bt-58....
Dahell?
Im assuming a fliskits dual bt-50 engine mount wont fit that... :/

 

[Kehoes23]

I meant like, is the body tube for this kit a bt-50 or bt-60

Do you have this?
If so find the same size body tube to find out if its a bt-50 tube or not.
Sorry I could not be of any more help to you.
I bought these when I was building LPR, now I mostly build HPR and have no spare LPR material to check for you

 

[kruland]

Lets see. BT-50 od = .95". Two side by side would be 1.9". OD of BT-58 is 1.54". Nope, not without some funky fairings which would ruin the scale nature of the kit. You could do two Bt-20s though.

The wonderful thing about Semroc is they have lots of different tubes - weird sizes, thick wall, etc. I suspect they stock this tube. Go here Semroc Body Tubes and see if you find something which matches. Here's a hint, it's not bt-50, 55, or 60

bt-58....
Dahell?
Im assuming a fliskits dual bt-50 engine mount wont fit that... :/

 

[Odo]

Do you have this? View attachment 146166
If so find the same size body tube to find out if its a bt-50 tube or not.
Sorry I could not be of any more help to you.
I bought these when I was building LPR, now I mostly build HPR and have no spare LPR material to check for you

I dont actually have the kit yet, I am just plotting away a custom build of it, but I needed to know the tube size..
Hm. Maybe someone else will come along

 

[bradycros]

Can anyone tell me what size body tube this semroc kit is? It says the body tube diameter is 1.54" (3.9 cm) Im sure that would mean something to one of you, because it certainly doesnt to me Im thinking of getting it and adding modifications but I am a scrub when it comes to body tube sizes.
https://www.semroc.com/Store/scripts/RocketKits.asp?SKU=KS-12

Thanks!

BT-58

 

[Odo]

BT-58

So a Bt-50 motor mount will NOT fit that tube, correct?

 

[bradycros]

So a Bt-50 motor mount will NOT fit that tube, correct?

Incorrect. A 24 mm (BT-50) motor tube will fit inside a BT-58 with the right centering rings.

 

[adrian]

So a Bt-50 motor mount will NOT fit that tube, correct?

A single BT-50 mount will, though you'll need to build your own centring rings. A dual motor mount definitely won't fit since a BT-50 is 0.976" wide, two BT-50 tubes side by side are therefore 1.952" wide and the MX-774's internal diameter is 1.498".

You could fit a dual BT-20 mount, i.e. a pair of 18mm motors - A, B or C class. And you'll still need to make your own centring rings. Or you could scratch-build the model entirely and upscale it, using at least BT-70 tubing; that's 2.175" inside, and a Fliskits dual 24mm (BT-50) mount is designed to fit that tube.

 

[Odo]

A single BT-50 mount will, though you'll need to build your own centring rings. A dual motor mount definitely won't fit since a BT-50 is 0.976" wide, two BT-50 tubes side by side are therefore 1.952" wide and the MX-774's internal diameter is 1.498".

You could fit a dual BT-20 mount, i.e. a pair of 18mm motors - A, B or C class. And you'll still need to make your own centring rings. Or you could scratch-build the model entirely and upscale it, using at least BT-70 tubing; that's 2.175" inside, and a Fliskits dual 24mm (BT-50) mount is designed to fit that tube.

I was under the impression the duel motor mounts arent any wider because both of the tubes are fitting into the same centering rings..?

 

[Rich Holmes]

So a Bt-50 motor mount will NOT fit that tube, correct?

By a "BT-50 motor mount" do you mean one that fits into a BT-50 body tube, or one that a BT-50 motor tube fits into?

A BT-58 has inner diameter 1.498". A BT-50 has inner diameter 0.950", outer diameter 0.976". So they're not at all the same size, but a BT-50 motor tube can be mounted inside a BT-58 body tube — given the appropriate centering rings. I don't see any BT-50 to BT-58 centering rings at Semroc, but maybe I'm missing something. Or you could make them yourself.

A dual BT-50 motor mount would have to be at least 2 x 0.976" = 1.952" diameter so would not fit into a BT-58 tube.

 

[Odo]

Ill clear up confusion.
Im trying to figure out if I can fit this:
https://www.fliskits.com/products/01prod_fs.htm
or this:
https://www.fliskits.com/products/01prod_fs.htm
Into the Semroc rocket without modifying the centering rings.

 

[Rich Holmes]

Unfortunately that doesn't clear up confusion, because the FlisKits site uses frames and when you cut and paste the URL, you just get the front page of the FlisKits site.

Give us FlisKits part numbers instead.

 

[adrian]

I was under the impression the duel motor mounts arent any wider because both of the tubes are fitting into the same centering rings..?

A dual BT-20 mount going into BT-58 will be the same size as a single BT-20 mount going into BT-58, i.e. the centring rings will be wide enough to fit inside the BT-58. BT-20 is about 0.74" diameter, BT-58 is about 1.5" inside diameter, so two BT-20's will fit in there - barely. The rings for a dual mount will be very thin at the sides.

BT-50 is about 1" across. How do you expect to fit two of those into a tube which is 1.5" across?

 

[adrian]

Ill clear up confusion.
Im trying to figure out if I can fit this:
https://www.fliskits.com/products/01prod_fs.htm
or this:
https://www.fliskits.com/products/01prod_fs.htm
Into the Semroc rocket without modifying the centering rings.

As has been pointed out, those are both the URL for Fliskits' main page. But it doesn't really matter because BT-58 is Semroc's own body tube size and Fliskits doesn't use it, which means no Fliskits motor mount will fit the MX-774 without altering or replacing the centring rings.

 

[Odo]

Unfortunately that doesn't clear up confusion, because the FlisKits site uses frames and when you cut and paste the URL, you just get the front page of the FlisKits site.

Give us FlisKits part numbers instead.

EMK2-13-55
and
EMK2-18-60

 

[adrian]

EMK2-13-55
and
EMK2-18-60

The first of those will put a pair of 13mm mini-engines into BT-55 and is too small to fit the MX-774. The second will put a pair of 18mm standard size engines into BT-60 and is too big to fit the MX-774.

The Fliskits dual BT-50 mounts are EMK2-24-70 and EMK2-24-70C. The latter has the mounts angled - if you've ever seen a Deuces Wild and want to build something similar using 24mm motors, that's the mount you'll want. Both mounts fit into BT-70, which is 2.175" inside diameter, which is why I suggested using that size for an upscaled MX-774.

 

[kruland]

EMK2-13-55
and
EMK2-18-60

I doubt if either would fit. The EMK2-13-55 has too small centering rings.

The EMK2-18-60 looks like it might work. You'll have to sand down the centering rings.

Your best bet would be to construct your own centering rings.

 

[Rich Holmes]

EMK2-13-55
and
EMK2-18-60

Those part numbers mean something: the first mounts 13 mm motor tubes into BT-55 body tubes, the second mounts 18 mm motor tubes into BT-60 body tubes.

Neither one fits into a BT-58 body tube.

BT-55 is 1.283" inner diameter. Too small.

BT-60 is 1.595" inner diameter. A tenth of an inch too large. In theory you might be able to cut the centering rings down to 1.498". But note that the two BT-20 motor tubes add up to 1.420", leaving only 0.078" — or 0.039" on each side. (Versus about 0.09" on each side for two BT-20 motor tubes in a BT-60.) (All that assumes there's no space at all between the two BT-20 motor tubes.)

 

[Rich Holmes]

At the risk of hijacking the thread... I look at those motor mounts and ask, why?

Why, for instance, cluster two 18 mm motors? The largest 18 mm Estes motor is C6. Two of those would double your total impulse and your average thrust. So, okay, why not use a 24 mm motor mount and load a D12? Or more generally, what can you get out of two adjacent, parallel 18 mm motors that you could not get out of a single 24 mm?

(Edit: Two B4-4s, because there isn't a C8-4?)

 

[Rich Holmes]

And just noticed one more thing. The MX-774 has a long boat tail with an aft diameter of 1.2", and the motor tube inserts directly into that. So you couldn't use cluster or a motor larger than 18 mm anyway, unless you threw away the boat tail, at which point you're completely redesigning the rocket. Unless you can find a boat tail of similar length that'll take a 24 mm motor tube.

 

[Marc_G]

At the risk of hijacking the thread... I look at those motor mounts and ask, why?

Why, for instance, cluster two 18 mm motors? The largest 18 mm Estes motor is C6. Two of those would double your total impulse and your average thrust. So, okay, why not use a 24 mm motor mount and load a D12? Or more generally, what can you get out of two adjacent, parallel 18 mm motors that you could not get out of a single 24 mm?

(Edit: Two B4-4s, because there isn't a C8-4?)

Because it's cool!

You are right... from a cost/ simplicity perspective, just go with a bigger motor. But clusters are awesome visually, and the element of risk/challenge about getting them all to light at once is sauce for the goose.

 

[luke strawwalker]

Here's a list of common body tube sizes...
View attachment SemrocTTTubesizechart[1].txt
Later! OL JR

 

[luke strawwalker]

The wonderful thing about Semroc is they have lots of different tubes - weird sizes, thick wall, etc. I suspect they stock this tube. Go here Semroc Body Tubes and see if you find something which matches. Here's a hint, it's not bt-50, 55, or 60


bt-58....
Dahell?
Im assuming a fliskits dual bt-50 engine mount wont fit that... :/

IIRC (going from memory) BT-58 is the size of the Apollo SM on the Saturn V kit... or is that BT-52...

Anyway, it's kind of a specialty size for a particular kit; most "production" kits don't use that tube size.

No, a BT-50 centering ring isn't going to fit. You'll have to make your own... Not hard, I do it all the time. You can make them out of regular cardboard, cardstock, or balsa wood... just requires a little work and effort.

Good luck! OL JR

 

[rocketguy101]

IIRC (going from memory) BT-58 is the size of the Apollo SM on the Saturn V kit... or is that BT-52...

Anyway, it's kind of a specialty size for a particular kit; most "production" kits don't use that tube size.

No, a BT-50 centering ring isn't going to fit. You'll have to make your own... Not hard, I do it all the time. You can make them out of regular cardboard, cardstock, or balsa wood... just requires a little work and effort.

Good luck! OL JR

and now that xacto sells a circle cutter very similar to the ol' trusty Olfa (and is available at Wally World) CRs are a snap!
https://www.xacto.com/products/cutt...ccessories/Designer-Series-Circle-Cutter.aspx

 

[plano-doug]

IIRC (going from memory) BT-58 is the size of the Apollo SM on the Saturn V kit... or is that BT-52... ?

JR, I got BT-58 on the SM as well. BT-52 was used as a "retainer tube" in the D-motor mount as I understand it. The Saturn V also used another oddball tube, the BT-63, which was a slip fit over the BT-60.

Doug

.

 

[JPVegh]

The short answer is no it won't work for a variety of reasons. If you want to get into clustering I'd recommend a BT-60 based kit with three 18mm mounts. A Semroc Ranger fits the bill nicely or you can modify a Big Bertha or a Patriot, a Clustered Vagabond might be a neat project. If you are inclined to go with canted motors then one of the Fliskits models is the way to go.