The [possible] solution for Ares-1 "vibrations"

gaetanomarano · 2008-01-29 00:35:41

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I've developed a (possible) solution for the Ares-1 "vibrations" problem explained in my latest ghostNASA article:

http://www.ghostnasa.com/posts/022novibrations.html

the idea is (simply) to put four small wings to the Ares-1 interstage to stabilize the flight and avoid too much vibrations

about the "shock absorbing" seats for the astronauts, I've already suggested it (six months ago) to allow (also) a LAND landing of the Orion WITHOUT the (1.5 mT heavy) landing airbags:

http://www.gaetanomarano.it/articles/031easyways.html

(it's the sixth idea in the article)

that (also) can avoid to use the (VERY DANGEROUS) jettisoned TPS:

http://www.gaetanomarano.it/articles/022orionTPS.html

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cIclops · 2008-01-29 00:42:28

the idea is (simply) to put four small wings to the Ares-1 interstage to stabilize the flight and avoid too much vibrations

The coupling between the external airflow and (possible) vehicle oscillations at the RSRB burnout altitude around 40 kms, would be too small to significantly reduce it.

gaetanomarano · 2008-01-29 01:07:33

The coupling between the external airflow and (possible) vehicle oscillations at the RSRB burnout altitude around 40 kms, would be too small to significantly reduce it.

I'm not sure that my idea can work, however, I suggest to test it in a wind tunnel

at multi-sonic speed four small wings works like bigger wings at subsonic speed and its aerodynamic force could be enough to replace the stabilizing effects of the Shuttle+ET in the stardard SRB launch

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RedStreak · 2008-01-29 15:20:55

Isn't the vibration problem more to do with the thrust, pressure, and internal shaking caused by the solid rocket itself rather than aerodynamics and air pressure?

If that's the case I don't think the wings would help, and I am saying this constructively. If these wings could be of use I'd presume putting them on the interstage portion so neither 1st or 2nd stages need to be redesigned.

The vibrations are at their worst during the end phase of the 1st stage if I recall as well.

gaetanomarano · 2008-01-29 16:18:11

...the wings would help...

the vibrations can't act down to up since the acceleration is very much higher

can't act up to down for the inverse reason

the vibrations can be only in the horizontal sense

the wings DON'T eliminate the vibrations but only its EFFECT stabilizing the rocket since, at multi-sonic speed, they works like "blades" in the air

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RedStreak · 2008-01-30 03:07:31

The vibration problem, in the end, might prove to be less of a worry in time. The article talking about it already stated a 5-stage actually would have a smaller occilation frequency than the 4-stage.

Thinking about it...although wings might not solve the problem...the solution might still lie in the interstage. Since the worst of the problem occurs later in flight, the interstage could play the buffer one way or another. Whatever they come up with to dampen the vibration they ought to optimize the dampening for the last minute or two before the 1st stage seperates. Considering the interstage will be disposable its very structure could be designed to take the blow at its expense with no harm to the 2nd stage or Orion further up.

GCNRevenger · 2008-01-30 07:42:42

...the wings would help...
the vibrations can't act down to up since the acceleration is very much higher
can't act up to down for the inverse reason
the vibrations can be only in the horizontal sense
the wings DON'T eliminate the vibrations but only its EFFECT stabilizing the rocket since, at multi-sonic speed, they works like "blades" in the air.

No.

The vibration is "up and down" along the axis of the rocket; the vibration is the result in rapid oscillatory changes to the acceleration caused by thrust fluctuations. Because the SRB produces so much thrust, even small changes to the thrust can induce large vibration.

Slapping some fins on to induce drag wouldn't help most likely, since it would have no effect on the trust changes which are the problem. Not to mention, their drag and weight would lower overall performance slightly.

gaetanomarano · 2008-01-30 15:20:41

...even small changes to the thrust can induce large vibration...

a further good reason to scrap the 5-segments SRB and go back to tested and reliable 4-segments SRB ...like I've said in last 1.5 years

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SpaceNut · 2008-01-30 21:22:38

Wow GCNRevenger, glad to see you back after the 6 month hiatus... I agree that adding fins to the SRB will do nothing to resolve the vibration issue if there is one that needs to be changed due to adding the extra length to the srb.

I would say if you think pipe organ tubes that the effect would come close to what we are looking at.

RedStreak · 2008-01-30 21:45:49

...even small changes to the thrust can induce large vibration...
a further good reason to scrap the 5-segments SRB and go back to tested and reliable 4-segments SRB ...like I've said in last 1.5 years
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Hey gaetanomarono, give it a rest. Why don't you stick to talking about the Ariane modifications you wanna do? Maybe you can get Europe's scrapped Heremes flying again...

gaetanomarano · 2008-01-31 00:07:51

Ariane modifications

time ago I've read a rumor about that but I don't know more, just hope they'll do it

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GCNRevenger · 2008-01-31 10:33:03

Ah yes, gaetano just hopes that NASA gives up building its own rockets and instead buys a mashup of French/German rocket parts... which, if memory serves, would require a huge "pylon" to join the three Ariane SRBs together, that in turn would weigh so much it would never fly...

...but I digress...

First of all small thrust oscillations may produce serious vibration, but not necessarily, as it depends on how large, how abrupt, and how often the oscillations are versus the mass of the booster.

I reiterate that a modern SRB is not a solid cylindrical block of fuel, but a channel runs the length of the fuel from nozzle to tip. This channel takes on a variety of shapes, which can give the booster different amounts of thrust at different times throughout the burn, which could be modified to solve the problem for all we know.

NASA doesn't even know yet, its just a possibility suggested by some calculations, by no means a definite no-fly issue yet. The fact that this has come up proves that NASA is taking the time to do the Ares-I development right, and not trying to band-aid a broken rocket after they've cut much metal. Good for them.

Even if the vibration exists, it isn't by any means a show-stopper; consider the Orion nuclear bomb rocket, which has the ultimate thrust oscillation (it rides the shock wave of small nuclear bombs), so why isn't it destroyed? Because it had a shock absorber between the pusher plate (which absorbs the shock wave's blast) and the rocket, damping out the massive blast to yield a smooth and continuous push.

Since some thrust variance on Ares-I's booster is nowhere near as harsh as trying to ride an atomic bomb blast, NASA could simply install some shock absorbers in the interstage above the booster. The booster, being made of thick steel, should be able to handle the vibration, so the problem would be solved.

cIclops · 2008-01-31 10:45:57

Hi GCN good to see you back and on form

Griffin gave a detailed outline of this possible resonance problem and its various solutions in his recent speech (at 45 mins) - at the beginning he presents a very clear outline of the reasons for choosing the Constellation architecture.

gaetanomarano · 2008-02-01 05:37:31

would require a huge "pylon" to join the three Ariane SRBs together, that in turn would weigh so much it would never fly.

three Ariane EAP exceed the 5-segments SRB power, so, the can lift also that "pylon" (whose weight can't be known now)

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GCNRevenger · 2008-02-01 08:11:16

No, the three EAP boosters exceed the SRB in thrust, not necessarily in lifting capacity.

Also, for other readers, ever notice the pattern that gaetano says NASA equipment will probably not work because we "don't know" it will, but defends all his ideas by saying we "don't know" that they won't.

The Atlas-V first stage for instance, which is roughly the same size as the pylon, weighs about 20MT by the way.

gaetanomarano · 2008-02-01 10:28:42

No, the three EAP boosters exceed the SRB in thrust, not necessarily in lifting capacity.
Also, for other readers, ever notice the pattern that gaetano says NASA equipment will probably not work because we "don't know" it will, but defends all his ideas by saying we "don't know" that they won't.
The Atlas-V first stage for instance, which is roughly the same size as the pylon, weighs about 20MT by the way.

I give no data of payload, etc. since (clearly) everything must be calculated and tested

the "pylon" is not so big like an Atlas-V and it's not the only possible solution (other can be simpler and lighter) ... however, 20 mT is not a so big weight compared with an SRB or an EAP

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GCNRevenger · 2008-02-01 10:37:11

Oh but you don't know, the pylon must withstand much higher loads because of the high thrust of the boosters tugging on the outside, rather than pushing from the end like a regular rocket. It might very well weigh much more.

Nor does this solution necessarily fix the vibration problem either, since you have a 50% increase in vibration with a somewhat lighter rocket than the Ariane-V.

SpaceNut · 2008-02-03 16:43:05

Another location that has a thread on the topic. NASA responds to Ares I thrust-oscillation issue

Opens well with a reference as to how much of an issue it is believed to be...

First Stage Design Problems Arise For NASA's Ares 1 Rocket

http://www.spaceref.com/news/viewnews.html?id=1244

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#1 2008-01-29 00:35:41

Re: The [possible] solution for Ares-1 "vibrations"

#2 2008-01-29 00:42:28

Re: The [possible] solution for Ares-1 "vibrations"

#3 2008-01-29 01:07:33

Re: The [possible] solution for Ares-1 "vibrations"

#4 2008-01-29 15:20:55

Re: The [possible] solution for Ares-1 "vibrations"

#5 2008-01-29 16:18:11

Re: The [possible] solution for Ares-1 "vibrations"

#6 2008-01-30 03:07:31

Re: The [possible] solution for Ares-1 "vibrations"

#7 2008-01-30 07:42:42

Re: The [possible] solution for Ares-1 "vibrations"

#8 2008-01-30 15:20:41

Re: The [possible] solution for Ares-1 "vibrations"

#9 2008-01-30 21:22:38

Re: The [possible] solution for Ares-1 "vibrations"

#10 2008-01-30 21:45:49

Re: The [possible] solution for Ares-1 "vibrations"

#11 2008-01-31 00:07:51

Re: The [possible] solution for Ares-1 "vibrations"

#12 2008-01-31 10:33:03

Re: The [possible] solution for Ares-1 "vibrations"

#13 2008-01-31 10:45:57

Re: The [possible] solution for Ares-1 "vibrations"

#14 2008-02-01 05:37:31

Re: The [possible] solution for Ares-1 "vibrations"

#15 2008-02-01 08:11:16

Re: The [possible] solution for Ares-1 "vibrations"

#16 2008-02-01 10:28:42

Re: The [possible] solution for Ares-1 "vibrations"

#17 2008-02-01 10:37:11

Re: The [possible] solution for Ares-1 "vibrations"

#18 2008-02-03 16:43:05

Re: The [possible] solution for Ares-1 "vibrations"

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