Think this will work?

[foamy]

These are the parts I've picked out—some of you know about these sizes far better than me.

I think it can be staged—am I mistaken? Will the booster tumble?

Will the rocket fly correctly with the fins up the body that far?

Best way to get a 'chute in there?

Unrelated: What does CATO mean?

http://i233.photobucket.com/albums/ee215/Savaje/Artwork%20Album/Picture15.png

[stefanj]

I would not count on that booster tumbling. The swept fins and balsa transition up front suggest that it will want to make a ballistic trajectory.

Upper stage stability might be a problem. The upper stage fins are VERY far forward. The balsa tail cone will add a fair amount of weight in the rear.

I'd put the parachute in the BT-70 section.

OTOH . . . really nice illustration job!

CATO = "Catastrophic failure," as in a motor failing in a spectacular fashion.

[GregGleason]

My take: the booster might tumble, but it depends on where the CG winds up. Making a "boiler plate" and hand tossing will tell you if you have "arrived".

What is more problematic is the upper stage. My guess is that it is an unstable design, with those fins as far forward as they are on the airframe. Unless you have a hollow balsa boattail, and I mean like at most 20 grams or so, and add some serious nose weight, you will have a 2nd stage "sky writer". I am not saying it is impossible, but I am saying you need to compensate heavily. An alternative is to add a set of clear fins near the end of the boattail to move the CP further aft.

If you haven't read the Handbook of Model Rocketry, 7th Edition by G. Harry Stine, there are some very good explanations on the relationship between the CG and CP for stable flight.

Interesting design, BTW.

Greg

[foamy]

I would not count on that booster tumbling. The swept fins and balsa transition up front suggest that it will want to make a ballistic trajectory.

Kinda what I was thinking.

Upper stage stability might be a problem. The upper stage fins are VERY far forward. The balsa tail cone will add a fair amount of weight in the rear.

Didn;t consider that. Doh!

I'd put the parachute in the BT-70 section.

My problem is that I don't think it 'd fit, but I don't know.

OTOH . . . really nice illustration job!

CATO = "Catastrophic failure," as in a motor failing in a spectacular fashion.

Thanks, I just redid a tech drawing (as close as I could get to scale) using off the shelf parts and thanks for the explanation. I thought it meant the motor going, but wasn't sure.

I appreciate the reply.

[foamy]

My take: the booster might tumble, but it depends on where the CG winds up. Making a "boiler plate" and hand tossing will tell you if you have "arrived".

What is more problematic is the upper stage. My guess is that it is an unstable design, with those fins as far forward as they are on the airframe. Unless you have a hollow balsa boattail, and I mean like at most 20 grams or so, and add some serious nose weight, you will have a 2nd stage "sky writer". I am not saying it is impossible, but I am saying you need to compensate heavily. An alternative is to add a set of clear fins near the end of the boattail to move the CP further aft.

If you haven't read the Handbook of Model Rocketry, 7th Edition by G. Harry Stine, there are some very good explanations on the relationship between the CG and CP for stable flight.

Interesting design, BTW.

Greg

Thanks Greg. I'll try and locate that book.

The design isn't mine—it's a Tiamat (C). It's the first missile (program) tested at Wallops FF in '46. Actually, I'm not sure what number this particular "C" model was as there was the Tiamat (A) that had only three fins and a very "Buck Rogers" type of booster. They switched to a different, single nozzle, four-finned booster and added another fin to the Tiamat (Tiamat [B]). The "C" model got the swept wings and it's the only line drawing of the Tiamat program that I can find. I'm going to check one last resource. I really dig the old-school look of these things.

The first one. Tiamat (A) Cordite propelled. They went with a more efficient fuel and booster for the rest of 'em. As far as I know, the A model got dropped from an airplane once and shot off the beach once. It started life as an Army Air Force air-to-air missile, but that didn't last long.

http://i233.photobucket.com/albums/ee215/Savaje/Artwork%20Album/134239main_wallops_tiamat-250px.jpg

[GregGleason]

Ha! When I first saw it I thought it looked like a rocket from the 1940s!

Interesting history, that one. Thanks.

http://upload.wikimedia.org/wikipedia/commons/thumb/4/4a/NASA_Wallops_Flight_Facility_historical_marker_01.jpg/450px-NASA_Wallops_Flight_Facility_historical_marker_01.jpg

Greg

[stefanj]

Interesting photo.

The booster's fins look more "delta" than swept. If you do that, you'll get a booster that is more likely to tumble. You can also put on fake angled motor tubes.

It is hard to tell from the angle shown, but the sustainer fins could be farther back than your design shows. In any case, you can move them back. Just leave a token gap between the rear end of the root edge and the rear end of the tube.

[Mark II]

There's a little bit more information about it here (http://www.designation-systems.net/dusrm/app1/jb.html).

Hughes JB-3 Tiamat. That is one wild looking rocket.

http://www.designation-systems.net/dusrm/app1/jb-3.jpg

[Mark II]

These links are more relevant to the version being discussed:

http://blog.modernmechanix.com/mags/PopularScience/3-1947/fly_to_moon/fly_to_moon_1.jpg

http://blog.modernmechanix.com/mags/PopularScience/3-1947/fly_to_moon/fly_to_moon_2.jpg

[foamy]

Interesting photo.

The booster's fins look more "delta" than swept. If you do that, you'll get a booster that is more likely to tumble. You can also put on fake angled motor tubes.

It is hard to tell from the angle shown, but the sustainer fins could be farther back than your design shows. In any case, you can move them back. Just leave a token gap between the rear end of the root edge and the rear end of the tube.

Would that technique pass for Sport Scale?

Here's the drawing I was going on:
http://i233.photobucket.com/albums/ee215/Savaje/Artwork%20Album/Picture11.png
And photos of both B and C being launched.
http://i233.photobucket.com/albums/ee215/Savaje/Artwork%20Album/66-c5696cad21.jpg

A front view of A.
http://i233.photobucket.com/albums/ee215/Savaje/Artwork%20Album/Picture12.png

[foamy]

These links are more relevant to the version being discussed:

http://blog.modernmechanix.com/mags/PopularScience/3-1947/fly_to_moon/fly_to_moon_1.jpg

http://blog.modernmechanix.com/mags/PopularScience/3-1947/fly_to_moon/fly_to_moon_2.jpg

THAT's the diagram I wanted and was looking for! Thanks Mark II—I appreciate it very much.

Looking at the diagram and the actual rocket, it appears that perhaps they trimmed the rounded fin tips at some point in the B's development. That and the specs don't read as others do. No matter, it's a reasonable scale drawing. Thanks again.

[Mark II]

This is a fascinating design, foamy. I had never heard of it until this thread. I must have gotten lucky with Google. I found the link to that Mechanix Illustrated article about 4 pages in on the search results. The article itself is absolutely precious! I remember reading articles just like it in mid 1950s-era encyclopedias that we had at home when I was growing up. :) Thank you for starting the discussion of this rocket. Now I'm eager to find out as much as I can about it, and I can't wait to see your build.

[Mark II]

I'm just thinking that it might be easiest at first to build a small prototype to take a standard 18mm B6-0 or C6-0 in the booster and a 13mm mini motor in the sustainer. By starting small you can tackle the stability issues first without worrying about either scale detailing or the thrust/weight power issue. Perhaps even build the first one as a single stage model, just to debug the stability of the full stack.

I am also thinking that the JB-3 must have had static stability because engine gimballing wasn't in wide use yet in 1945. Those flaps were for steering, I would think, and so otherwise the missile was passively stabilized by those huge fins. That's my guess, anyway. So if Hughes could achieve stability with that basic shape and fin arrangement, then it should be possible for us to do that as well in a model, right? Here I'm just thinking about the JB-3 Tiamat sustainer.

Cool project!

[foamy]

I'm just thinking that it might be easiest at first to build a small prototype to take a standard 18mm B6-0 or C6-0 in the booster and a 13mm mini motor in the sustainer. By starting small you can tackle the stability issues first without worrying about either scale detailing or the thrust/weight power issue. Perhaps even build the first one as a single stage model, just to debug the stability of the full stack.

I am also thinking that the JB-3 must have had static stability because engine gimballing wasn't in wide use yet in 1945. Those flaps were for steering, I would think, and so otherwise the missile was passively stabilized by those huge fins. That's my guess, anyway. So if Hughes could achieve stability with that basic shape and fin arrangement, then it should be possible for us to do that as well in a model, right? Here I'm just thinking about the JB-3 Tiamat sustainer.

Cool project!

I've just been thinking a single stage may be the way to start off. A smaller size hadn't hadn't occurred to me—thanks for the idea.

From the little info I've turned up, it appears that the three finned version had stability problems at certain speeds/angles of attack. After they had given up on the air-to air missile bit (with that model), they continued testing for control—I think that was the idea behind sending it to Wallops. I have a de-classified report on the "C" model and a link to a book (that can be read online) about the first years at Wallops that was sent to me by the Chief Librarian at Wallops (it helps to have a NASA email address). When I get to work on Monday, I'll pass those tidbits on to you. There's a couple of pages in there on the Tiamat (that's where the good photos came from). Tomorrow, I'll also put in a request to Langley which was suggested by WFF as they told me it was a Langley project. It's hard to get real info on this rocket. There might be a survivor around somewhere—the Air Force Museum traded Wallops one they had for a "Scout" at some point. It's not on display with the other rockets just off the base. Where it is now, or if it still exists, I don't know. I'm going to try and finagle some passes to WFF for an upcoming rocket launch and see what can be found out while I'm there (if I can get the pass). If you should turn up anything—please let me know, if you would be so kind. I'd appreciate it. It's such a cool looking rocket. If Langley has anything, I'll pass it on.