1/100 Saturn 1B clone

[dtomko]

I have finally accumulated all the parts I need to start a 1/100 Saturn 1B clone. Paul Graf has beautiful vacuum-formed wraps and resin shroud and fins. I may use the resin fins as masters to vacuum form fins as on the original; the resin fins might crack on a hard landing. I have a length of BT-80 for the main body and lower BTs. I will insert a piece to increase the diameter for the bottom tube. The fuel tank tubes are cut from Totally Tubular tube. I also have the Estes Saturn V command module BT and plastic parts. I will cut my own centering rings. The only really tricky part (I think ) will be creating the core "exhaust tube." It's an odd 1.15" in diameter, so I will try cutting down a spare BT-56 I have (I'm out of BT-55s).
I would appreciate any advice!

Drew Tomko

 

[Fred]

Hi drew,
I dont suppose you could let me know what size those tubes are. i have a set of 100 scale bits coming from paul and i have the plastic bits from a estes saturn v for the capsule.
Cheers
fred

 

[doug_man_sams]

Originally posted by dtomko
The only really tricky part (I think ) will be creating the core "exhaust tube." It's an odd 1.15" in diameter, so I will try cutting down a spare BT-56 I have (I'm out of BT-55s).

I would appreciate any advice!

Drew,
My instructions label that part as 1-3/16" diameter (=1.1875"). I suggest getting a piece of Quest T-30. It's 1.18" od. You might have to buy a sacrificial kit to get it, but with a 40% coupon, it shouldn't be too bad.

I'll try to put calipers on mine (in the box) and see what od I measure, just to be sure that T-30 isn't too big.

Doug

 

[dtomko]

Thanks, Doug. Much obliged.
I just saw that Semroc's T-11 is 1.17" in diameter. I think that may be the way to go.

Fred, here are the tube measurements:
Fuel tubes:
0.705" diameter, 7 7/8" long for Estes version; 8" for Centuri 2 engine cluster version) Totally Tubular has these
Core tube:
Estes: 11" long, 1.15"??? diameter
Centuri: 8 1/2" long, 1 3/16 diameter
Main tube:
BT-80 (actually a bit wider diameter on original, 2.626", but BT-80 will work), 7 5/8 long - Estes
Centuri: 7 9/16" long
Bottom tube:
Estes: 2.706" diameter, 1 3/8" long(need to make this one) - Centuri: 2 11/16" diameter, 1 13/32" long
And the BT-58 service module tube

Drew

 

[Fred]

Hi drew,
thanks very much
Cheers
Fred

 

[dwmzmm]

Originally posted by fred22
Hi drew,
thanks very much
Cheers
Fred

Fred, I think these guys pretty much answered your questions about the 1/100 scale Saturn 1-B. Sorry that I haven't had the
chance to get mine out to do some measuring. That's why it's
great to be on forums like this (and others), somebody will always be willing to jump in and help. Model rocketeers are the
best!!

 

[DeWain]

Drew, Fred, Doug et al.,

I had thought of cloning a 1/100 1B, but canned the project when I thought that it would be too hard to to get all of the parts. Now I just *have* to add this to my build queue to go along with my just-completed Estes 1/100 Saturn V.

If you can give me some info on how to contact Paul Graf, I should be able to get most of the parts now... except for that darned BT-58 body tube. Any info on where to get one? I have some spare Quest T-30 that I could trade with you if you have spare BT-58.

Any info on why the body tube lengths are quite different between the Estes and Centuri versions (I thought that what Estes did was to re-release the odl Centuri version... but now it seems that they must be two quite different kits). Between the Estes and the Centuri kits, which one is more scale?

Oh... and yes... where were you planning to get the decals? Tango Papa?

Thanks,
DeWain

 

[dwmzmm]

Originally posted by DeWain
Drew, Fred, Doug et al.,

Any info on why the body tube lengths are quite different between the Estes and Centuri versions (I thought that what Estes did was to re-release the odl Centuri version... but now it seems that they must be two quite different kits). Between the Estes and the Centuri kits, which one is more scale?

Oh... and yes... where were you planning to get the decals? Tango Papa?

Thanks,
DeWain

I've built both Estes & Centuri Saturn - V's, and the Centuri's
Saturn 1-B & both Apollo Little Joe - II's (1/45 & 1/100). While I
admired and respect both companies, I think the Centuri kits have
more pronounced details than the Estes original Saturn - V.

Just recently, I finished building the Centuri big Saturn. You can
see some pics in the following link...on page 6 the bottom three
pictures, and on page 7, the top five:

https://www.nasarocketclub.com/gallery/album25?page=6

Oh yes, I've lost the 1/100 scaled Apollo Little Joe - II (must have
lost it during a move, or something like that), and I DO have the
original Estes 1/70 scale Saturn 1-B "still-in-the-box" awaiting
assembly.

Do get your decals from Tango Papa Decals. I just got my order
from them several weeks ago to complete my Centuri 1/35 scale
Mercury Redstone (again, a vintage kit!!), and the decals from
Tango Papa are OUTSTANDING.

 

[dtomko]

DeWain,
Here's the thread with Paul's info:

https://www.rocketryforum.com/showthread.php?s=&threadid=26498

He does great work and at extremely reasonable prices.

As far as the differences in tube measurements between Estes and Centuri, in the case of the core and fuel tank tubes it's because Centuri used a 2 18mm cluster and Estes used a single 24mm arrangement. On the Centuri version, you had to slice open two of the fuel tank tubes to make room for the 2 engine tubes; Estes simplified this using a longer core tube and slightly shorter fuel tank tubes. Otherwise, I know Estes used the Centuri wraps and I am pretty sure the same tubes. It seems that Centuri was more "precise" in their measurements (I've taken them from the Centuri 1B instruction sheet on Jim Z's site), going to 16th and even 32nd of an inch, while Estes seems to round to 8ths.

I got the BT-58 directly from Estes when the latest rerelease of the Saturn V came out. I called Christine and ordered a set - this was several years ago- and got all the plastic parts and BT-58. You can easily get one these days by buying a Gauchito kit, same tube, and you'll get a smooth capsule as well. It's worth contacting Estes to see if you can still get the package, so you have the escape tower and RCS motors.

Yes, I plan to use Tango Papa decals. I have ordered from him many times, and although I've had a few quibbles (some inaccuracies on the Orbital Transport sheet), his quality is excellent. He also has decals for the roll patterns and perhaps even the silver on the service module.

I will probably order a Semroc T-11 for the core tube and see how that works.

Drew

 

[dtomko]

Originally posted by dwmzmm
I've built both Estes & Centuri Saturn - V's, and the Centuri's
Saturn 1-B & both Apollo Little Joe - II's (1/45 & 1/100). While I
admired and respect both companies, I think the Centuri kits have
more pronounced details than the Estes original Saturn - V.

Do get your decals from Tango Papa Decals. I just got my order
from them several weeks ago to complete my Centuri 1/35 scale
Mercury Redstone (again, a vintage kit!!), and the decals from
Tango Papa are OUTSTANDING.

Dave,

I agree; the vacuum formed Centuri wraps were much more accurate. The original Estes paper wraps tended to disappear under a couple coats of paint. The latest Estes Sat V has the Centuri wraps. Mine is still in the box.

Please check your Tango Papa Mercury Redstone decals. On mine, on the big "United States" the second T in States is off center. I didn't realize this until after I had applied them and it was too late. That really annoyed me. Tom may have fixed it by now.

Drew

 

[doug_man_sams]

Originally posted by dtomko
Thanks, Doug. Much obliged. I just saw that Semroc's T-11 is 1.17" in diameter. I think that may be the way to go.

Drew,

I just measured the core tube on my 2048. I got ~1.15". It's hard to not deform the tube with the calipers, but the consensus of repeated measurements was about 1.15".

Can't say whether 2/100 will make any difference, but it'd be a major bummer if the tank shroud won't fit aroud the tanks.

Doug

 

[dwmzmm]

Originally posted by dtomko
Dave,

I agree; the vacuum formed Centuri wraps were mauch more accurate. The original Estes paper wraps tended to disappear under a couple coats of paint. The latest Estes Sat V has the Centuri wraps. Mine is still in the box.

Please check your Tango Papa Mercury Redstone decals. On mine, on the big "United States" the second T in States is off center. I didn't realize this until after I had applied them and it was too late. That really annoyed me. Tom may have fixed it by now.

Drew

The decals I got for the Mercury Redstone looks good to me...here's a link to a very closeup of the model with the decals:

https://www.challenger498.org/gallery/album25/FH000017?full=1

I don't see anything wrong, unless I'm missing something.

 

[jflis]

Originally posted by dtomko
Dave,

I agree; the vacuum formed Centuri wraps were much more accurate. The original Estes paper wraps tended to disappear under a couple coats of paint. The latest Estes Sat V has the Centuri wraps. Mine is still in the box.

Please check your Tango Papa Mercury Redstone decals. On mine, on the big "United States" the second T in States is off center. I didn't realize this until after I had applied them and it was too late. That really annoyed me. Tom may have fixed it by now.

Drew

I'd have to pull my NASA drawings to be sure (Lord knows where they're buried... ) but if you had *scale* corrugations on the 1:100 scale Saturn 1B, wouldn't they be very *very* small, almost un-noticable? It always seemed to me that the raised vacuum formed wraps, while they looked very cool, were way off with regard to true scale.

Or am I out to lunch on this one??

 

[dtomko]

Originally posted by doug_man_sams
Drew,

I just measured the core tube on my 2048. I got ~1.15". It's hard to not deform the tube with the calipers, but the consensus of repeated measurements was about 1.15".

Can't say whether 2/100 will make any difference, but it'd be a major bummer if the tank shroud won't fit aroud the tanks.

Doug

Thanks, Doug!
BTW, I think we went through this a few years ago on the Old Rockets forum!

The difference may be an issue since the BT-80 is already a bit smaller than the original BT and the fuel tubes will have to fit inside it.

OK, I'm lousy at math. Is there any formula that would tell me how much of the circumference I would have to cut out of the BT to go from a BT-56's 1.346" diameter to 1.15" diameter?

Drew

 

[dwmzmm]

Originally posted by jflis
I'd have to pull my NASA drawings to be sure (Lord knows where they're buried... ) but if you had *scale* corrugations on the 1:100 scale Saturn 1B, wouldn't they be very *very* small, almost un-noticable? It always seemed to me that the raised vacuum formed wraps, while they looked very cool, were way off with regard to true scale.

Or am I out to lunch on this one??

You're right, Jim. John Pursley, who everyone knows is probably
the number one expert on the Saturns, tells me the details on the
Centuri Saturns were exaggerated so the models would look
better from the distance. I also had the Estes Saturn - V's back
in my early years and can tell you that too much painting will
coverup those corrugations. Since those Estes wraps were already white in color, I was careful not to paint too much on
them and concentrate mostly spay painting the bodytubes and
areas other than the corrugation wraps. I still have the Estes
Saturn - V "in-the-box" awaiting assembly, along with (sigh) so
many other classic kits needed to be built!

BTW, Pursley is the one who did the work on the main details of
the Apogee Saturn 1-B and Saturn - V. I've seen his work in his
house...he doesn't live that far from me. He has a fantastic flair for accurancy in details for scale models!

 

[dtomko]

Originally posted by jflis
I'd have to pull my NASA drawings to be sure (Lord knows where they're buried... ) but if you had *scale* corrugations on the 1:100 scale Saturn 1B, wouldn't they be very *very* small, almost un-noticable? It always seemed to me that the raised vacuum formed wraps, while they looked very cool, were way off with regard to true scale.

Or am I out to lunch on this one??

Jim,
You are absolutely right; the vacuum formed wraps are way overscale, but look way better anyway!

I think the original Estes paper wraps just didn't "look" like corrugations; they seemed wide and flat. If you wanted to be more accurate, you could probably find Evergreen corrugated sheet that works better.

Drew

 

[dtomko]

Originally posted by dwmzmm
The decals I got for the Mercury Redstone looks good to me...here's a link to a very closeup of the model with the decals:

https://www.challenger498.org/gallery/album25/FH000017?full=1

I don't see anything wrong, unless I'm missing something.

Dave,
Yours looks fine. Here's a closeup of mine. You can see the lower T is off center to the left. I could have cut it out, but by the time I noticed, the decals had begun to set
Drew

 

[Fred]

Originally posted by dwmzmm
Fred, I think these guys pretty much answered your questions about the 1/100 scale Saturn 1-B. Sorry that I haven't had the
chance to get mine out to do some measuring. That's why it's
great to be on forums like this (and others), somebody will always be willing to jump in and help. Model rocketeers are the
best!!

No worries and you are right about rocketeers great bunch including yourself
Cheers
fred

 

[dwmzmm]

Originally posted by dtomko
Dave,
Yours looks fine. Here's a closeup of mine. You can see the lower T is off center to the left. I could have cut it out, but by the time I noticed, the decals had begun to set
Drew

Ouch! That off centered "T" does hurt! BTW, on the pics of my
Centuri Saturn - V from the previous posts, the vertical motion
decal that's on the S-II stage (next to the vertical "UNITED STATES" decal) is not quite in the correct position (Centuri's
fault) and does have one minor defect (hard to see in any of
those pics). I'll be getting another set of Saturn - V decals from
Tango Papa to correct it (the decals on the pictured Saturn - V
ARE those that came with the Centuri kit...yes, they were still
in great shape even after all those years in storage before I built
it a few months ago!).

 

[dwmzmm]

Originally posted by fred22
No worries and you are right about rocketeers great bunch including yourself
Cheers
fred

I'll "make it up" sometimes in the near future! Let's see, we
still have the Black Brant - II's, and what else?!

 

[jrbrohm]

Originally posted by dtomko
Thanks, Doug!
BTW, I think we went through this a few years ago on the Old Rockets forum!

The difference may be an issue since the BT-80 is already a bit smaller than the original BT and the fuel tubes will have to fit inside it.

OK, I'm lousy at math. Is there any formula that would tell me how much of the circumference I would have to cut out of the BT to go from a BT-56's 1.346" diameter to 1.15" diameter?

Drew

Hi Drew;

We sure did; check for the discussion in the Messages #25499 - 25503 area.

The center tube measures out at 1.15" as you and Doug have noted; the fuel tanks measure at 0.705". When arranged around the center tube, the outer diameter of the complex will be 1.15" + 2*0.705 = 2.56" - definitely a tight fit with the BT-80 ID. In the Old Rockets discussion, this was pointed out and it was suggested that we might want to use the 0.700" tube that Totally Tubular has. With paint build up, even the 0.700" tubes might be tight so keeping the ends paint-free will likely be important.

Regarding your question as to how much to remove from a BT-56 to get to a closed diameter of 1.15", use the following:

x=(pi)(D1 - D2), where x is the amount that must be removed, D1 is the BT-56 diameter, and D2 is the new diameter. Turn the crank and you'll get 0.616", something just less than 5/8"

 

[doug_man_sams]

Originally posted by jrbrohm
The center tube measures out at 1.15" as you and Doug have noted;(snip)

John,

Didn't you have a list of Estes part numbers somewhere? Or is that only nosecones? I was trying to look up the number for the 1.15" tube (30397, IIRC) , but couldn't find anything.

BR,
Doug

 

[dtomko]

John,

Thanks for that info! I will go back to the archives to refresh my memory.

I actually have the TT .700" tubes; I had forgotten they are a hair less in diameter, which is good news! I will play around with cutting a core tube and see if I can work something out.

Drew

 

[jrbrohm]

Originally posted by doug_man_sams
John,

Didn't you have a list of Estes part numbers somewhere? Or is that only nosecones? I was trying to look up the number for the 1.15" tube (30397, IIRC) , but couldn't find anything.

BR,
Doug

Hi Doug;

You can find the part numbers and tube lengths for virtually all of the Estes kit line in the Estes Body Tube/Kit Reference list, presently located on Ye Olde Rocket Forum at the following location:

https://www.rocketshoppe.com/info/Estes_Body_Tube_List.pdf

Your memory is pretty good - you got all of the digits, but just a little out of order. In the #2048 kit, the piece of BT-58 supplied in the kit was assigned P/N 030397; the Core Tube (the 1.15" OD tube) was assigned P/N 030379.

 

[jrbrohm]

Originally posted by dtomko
John,

Thanks for that info! I will go back to the archives to refresh my memory.

I actually have the TT .700" tubes; I had forgotten they are a hair less in diameter, which is good news! I will play around with cutting a core tube and see if I can work something out.

Drew

Hi Drew;

I'll try to summarize here the key points from that Old Rockets discussion from a year or so ago. We were in a discussion with Paul Graf about reproducing the wraps for the Saturn 1b (I have a set of Paul's repros, and they're pretty nice) and the point was made that a number of the tubes in the 2048 kit were "special" diameter. This caused some musing over possible substitutions, and that's when the discussion zeroed in on using BT-80 for the S-IVB section.

One of the curious things about the 2048 Saturn 1b is that the tube supplied to represent the S-IVB (P/N 030436) isn't actually a BT-80. This kit part has an OD of 2.626" and a wall thickness of 0.013"; doing the math shows that the ID of this tube is 2.6" exactly, and if one has the chance to directly compare it to a stock BT-80, these little differences become noticeable.

What makes this curious is the fact that the prototype S-IVB had an OD of 260" exactly; at 1/100 size, one would think that regular old BT-80 would be the logical choice for the model. My speculation as to why Estes didn't use BT-80 centers on the tube choice they made for the Redstone tanks (these measure out at an OD of 0.705" in the model) and also to design in a little allowance for construction variances. When the Redstone tanks are grouped around that 1.155" Core Tube, the complex has a total OD of 2.565" - this would exceed the specified ID of the normal BT-80. At least the fit would be tight, and paint would further complicate things. By contrast, this complex would slip-fit rather nicely into the kit-supplied S-IVB tube.

For cloning purposes, moving to a BT-80 for the S-IVB and using TT .700 tubes for the Redstone tanks offers two benefits:

- These tubes would be more exact scale-wise for these portions of the rocket.

- They happen to be currently available.

Paul's effort to reproduce wraps that fit a BT-80 OD puts the icing on the cake.

One of the consequences stemming from the use of these available tubes is the likelihood that the stock Core Tube will still cause things to be a little tight. This is in part due to the normal wall thickness of BT-80. In the prototype, the Redstone tank complex had a total OD of 257"; this would leave a small gap between the outer tank and the inside of the interstage fairing of 1.5". In our 1/100 size model, this would be 0.015", and I think this explains how Estes arrived at the parameters for the tube they supplied for the S-IVB. Going back to our consequence - using the stock Core Tube and the TT .700 Redstone tanks gives us an OD of 2.555" versus a BT-80 ID of 2.558". All of this means that we would want to reduce the OD of the Core Tube a little bit so that we have some construction and paint margin.

Hope all this helps;

 

[jrbrohm]

Originally posted by dtomko
John,

Thanks for that info! I will go back to the archives to refresh my memory.

I actually have the TT .700" tubes; I had forgotten they are a hair less in diameter, which is good news! I will play around with cutting a core tube and see if I can work something out.

Drew

Drew - one more thing:

Concerning reducing the diameter of the Core Tube, I forgot to point out that going with the TT .700 Redstone tubes gives us some flexibility here. If we take 8 TT .700 tubes and arrange them in a circle just tangent to each other, the OD of this complex is 2.529" - plenty of room to fit inside a BT-80 (although admittedly less than scale - but who's checking?). This arrangement leaves a Central Void (where the Core Tube would fit into) that has an OD of 1.129". So when we say we want to reduce the Core Tube diameter, we're talking about a reduction in circumference of about 3/32" using that formula I provided earlier. Chances are we don't want to shrink the Core Tube that small, as we need a hair's gap between the Redstone tanks to allow for paint.

Splitting hairs when I can hardly afford to!!

 

[doug_man_sams]

Originally posted by jrbrohm
You can find the part numbers and tube lengths for virtually all of the Estes kit line in the Estes Body Tube/Kit Reference list, presently located on Ye Olde Rocket Forum at the following location:
https://www.rocketshoppe.com/info/Estes_Body_Tube_List.pdf

Thanks, John. It's on my harddrive now. Top quaiity stuff, as always BR, Doug

 

[dtomko]

Thanks again, John. This is extremely helpful!

The good thing is that the fuel tank tubes will be painted before assembly so one can test fit a core tube arrangement. I slid the .700 tubes in the resin shroud today and they fit the cut outs nice and snugly. You can see a hair (I don't have much of that stuff either ) gap between the tubes, but of course that will go with a coat or two of paint.

Regarding the odd tube size for the S-IVB, your explanation makes a lot of sense. Also, this was originally Centuri's design, and their BT sizes differed a bit from Estes'.

I just had another thought about the core tube: it might be simpler to run a BT-50 all the way up and use balsa shims around it to fill in the spaces between the core and the fuel tank tubes. The OD of the BT-50 is .976 and we want to get to 1.129; that leaves a .153 difference. Since pairs of tubes are on opposite sides of the core, each shim should be .0765" thick.

Does that make sense?

Drew

 

[sandman]

8 TT .700 tubes and arrange them in a circle just tangent to each other, the OD of this complex is 2.529"

John, LOL...Maybe you missed an obvious step that "overcomplicated" the process a bit.

Let me explain.

The 8 tank tube were actually Redstone missle bodies 70" in diameter sooooooo 1/100th scale would be....0.70" in diameter.

The main upper body of the Saturn 1B was 260" in diameter sooo in 1/100th scale it would be 2.60" (that's a BT-80!).

That's why those sizes work so well.

If you make your own centering ring then you could just use a BT-50 for the center tube.

I planned on taking a 50/55 spiral wound centering ring, putting it onto the central BT-50 and just pealing off paper until the ring fits the I.D. formed by the tank tubes.

Much simpler...to me.

 

[dtomko]

I think Sandman has the best solution! That's definitely the least complicated way to go.

Drew