Interstage design

[Jason Thompson]

This just occurred to me while looking at a video of the N-1. The interstage sections between the lower stages of the N-1, as with those on the Vostok and Voskhod rockets, are simply an arrangement of metal trusses. This seems like an excellent weight saving design idea. Is there a particular reason for this design not being incorporated on any American rocket? Likewise, the fins on the bottom of the Saturns seem a sensible design for stability, so where did the design incorporated on the N-1 and the Soyuz escape system of a set of horizontal mesh panels come from?

[gwiz]

I'm not enough of a structural engineer to know whether typical western skin/stringer construction is heavier or lighter than the Russian-style open truss, though it's obviously better aerodynamically. The Titan missile had a partially open interstage structure which was because the second stage was ignited before the first was jettisoned.

The grid-like fins were not used in the west because nobody came up with the idea. I've a vague idea that after they were first revealed on the Soyuz, they were used for some small western missiles, but I wouldn't swear to it. They have an obvious virtue of being easy to store for low drag when they are not needed.

[scooter]

Correct me if I go astray here, but I believe that the Titan II had a similar design, they refered to it as "fire in the hole". Basically the open interstage allowed the 2nd stage to start burning before the first stage was dropped. The Titan's interstage wasnt an "open truss" like the Russian designs, but has vent holes around the periphery of the interstage area. Even with this, the upper portion of the stage was physically blown away, with a lot of debris flying. IIRC, Pete Conrad remarked on the extensive debris with the thought that "the damn thing just blew up!!"
Dave

[Jason Thompson]

Yes, I had forgotten the Titan II vent holes. I recall seeing the staging footage from onboards with the upper section disintegrating. The debris is even apparent on some ground tracking shots. Gemini 10 went one better: the oxidiser tank exploded during staging!

[Al Johnston]

gwiz said:

The grid-like fins were not used in the west because nobody came up with the idea. I've a vague idea that after they were first revealed on the Soyuz, they were used for some small western missiles, but I wouldn't swear to it. They have an obvious virtue of being easy to store for low drag when they are not needed.

Like these?



I've not seen anything similar on Western AAMs

[mid]

This just occurred to me while looking at a video of the N-1. The interstage sections between the lower stages of the N-1, as with those on the Vostok and Voskhod rockets, are simply an arrangement of metal trusses. This seems like an excellent weight saving design idea. Is there a particular reason for this design not being incorporated on any American rocket?

I should suppose it is a matter of different engineers, different designs. I would say that the American design was likely a darn sight better aerodynamically, but I'm rather glad none of our rockets looked, or performed like their Soviet counterparts.

Given the N-1's success rate, I'm glad we developed the Saturn V, and that it took nothing from Soviet booster design!