Griffin Favors Shuttle SRB for Launching CEV

[najab]

><i>why is everybody so convinced a pure lifing body can't land on a runway?</i><p>I think for most people, the concern isn't that it can't land on a runway as much as that it <b>must</b> land on a runway. 99.999999% of the Earth's surface is, unfortunately, not covered by a runway, which seriously limits the landing opportunities of a lifting body/winged space vehicle.</p>

 

[spacefire]

isn't it the same for airplanes? <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[spacefire]

it's probably an issue of configuration. you are planning to stack SRBs on top of eachother or what?<br />4 SRBs around a 3rd stage central core, with 2 SRBs acting as first stage and 2 acting as second stage, I don't see why it wouldn't work! <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[vt_hokie]

I believe this was an all-solid booster:<br /><br />http://www.daviddarling.info/encyclopedia/C/Conestoga.html

 

[darth_guano]

<font color="yellow">why is everybody so convinced a pure lifing body can't land on a runway</font><br /><br />Sure as has been pointed out, a lifting body can land on a runway. However the inherient design of a "true lifting body" doesn't generate enough lift at low air speeds to safely land, so you've got the problem of coming in too steep and too hot. Hence the steerable parafoil that was being developed for the X-38.

 

[lunatio_gordin]

Ever watch the X-38 land? it was pretty cool.

 

[j05h]

>I'd say capsule with steerable parafoil, skid landing is <br /> />pretty simple too with todays technology. It was tested <br /> />on X-38 and parafoils in general have been around long >enough. This would avoid salt water and buoyancy >issues, with basically no extra added weight and slight >increase in complexity.<br /><br />I'm actually not a fan of salt water landings, either. the capsule I'd like to see developed lands in big freshwater ponds at KSC. Parafoils are great for soft landings on land. I'm not a fan of landing rockets (Soyuz), mandatory active control (lifting bodies) or pushing the materials envelope (Shuttle). <br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[gunsandrockets]

"Seems to add unnecessary weight and complexity to me - what's the advantage over fixed wings such as an X-37 type of configuration? "<br /><br />The Andrews-Space CEV concept came up as a subject earlier in this SRB-CEV thread. See this...<br /><br /><br />Shorter link<br /><br /><br />...the short answer to your question is the Andrews-CEV seems to have a relatively large span straight wing with high lift devices such as flaps. That makes a huge difference to the subsonic glide slope and landing speed compared to a tailess stub-delta wing such as the X-37.

 

[j05h]

spacefire- the shape may be simple but if there is a computer crash or error (think Soyuz TMA-1) then your lifting body splashes itself across the sky. The Soyuz in question produced an uncomfortable but survivable 8G ballistic reentry. KISS stands for Keep It Super Simple and lifting body/winged spacecraft automatically violate the principle. A lifting body is not a capsule with fins and landing gear - a proper capsule is axisymmetric and anyone that delibrately puts holes (wheel wells, fuel feeds on Shuttle) through a heatshield needs their head checked. Requiring control surfaces for reentry is a very big problem, especially when those hydraulics/servos have been in LEO or deep space for several years. It's not just wings that are my concern. <br /><br />The "Comet" airliner was one of the original commercial passenger planes. It had square windows that would burst at altitude. Later versions switched to our now "normal" looking round airliner windows. Just because something looks right doesn't mean it's the best solution, please think outside the box. <br /><br />Shorter link<br /><br />That said, it looks like I'm in the minority as all of the current crop of next-gen craft (CXV, Kliper, CEV, etc) seem to be something other than a straight-up capsule. Northrup's submission (the soyuz clone) is the only possible capsule coming down the line, and I think that (if built) it will be the safest and most successful of the new crop. ATK's "simple, safe, soon" sales line is exactly what should lead to development of a capsule instead of another profile. <br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[gunsandrockets]

"So someone is going to have to explain to me why a single stick SRB with an upper stage can get into space but an SDHLV with SRBs as a first and second stage followed by a liquid third stage will not work. "<br /><br />Sure, glad to try. I start by checking out some of the baseline data for the SRB...<br /><br />http://www.astronautix.com/lvs/shuttle.htm<br /><br /><br />...I find the SRB with a loaded mass of 589,670 kg and an ideal vacuum thrust of 1,174,713 kgf. Unless I misunderstand my units of measurement I see a big problem immediately. A serial two stage SRB doesn't have enough thrust to get off the ground!<br /><br />Okay let's bypass this problem by changing the proposed configuration. Add another SRB parallel to the first stage for added thrust, so now the configuration is a two stage rocket using three SRB's. There is barely enough thrust to lift this combo off the ground, so we will ditch the liquid third stage. What kind of burnout velocity would our three SRB rocket have?<br /><br />Let's assume the CEV is 30 tonnes. The launch vehicle then has liftoff mass of 1,770,000 kg. The launch vehicle weight when the dual SRB first stage burns out is 763,000 kg, that give a mass ratio of 2.31. And since the SRB have an ISP of 237, that combined with a mass ration of 2.31 gives a launch vehicle speed of roughly 2 kms at first stage burnout.<br /><br />The dual SRB 1st stage is jettisonned and the second stage SRB now kicks in. The second stage has a loaded mass of 620,000 kg and a burnout mass of 116,000 kg for a mass ratio of 5.34. I'm pretty sure it takes a mass ratio of about 12 to triple the delta vee of a rocket compared to it's exhaust velocity. So I'm going to guess a mass ratio of 5.34 would be double the exhaust velocity (a figure I'm almost certain that is too high, but I'm being generous here). That gives a burnout delta vee of way less than 5 kms, so added to the delta vee of th

 

[skywalker01]

It was somewhere around 1967 that NASA did a hypersonic/supersonic/subsonic wind tunnel study on an autogyro system for the Apollo capsule that would have allowed it to make a soft landing on the White House lawn on its return from the Moon.<br /><br />In other words, capsules aren't limited to splashing down in the ocean.

 

[gunsandrockets]

All kinds of claims and counterclaims about lifting bodies are made and often people aren't even talking about the same lifting body. To be perfectly clear the universe of lifting body designs cover a very large range of lift to drag and cover a very large range of mission goals.<br /><br />Some of the early capsule configurations studied for the Apollo Project were lifting bodies, one was a symmetrical conical capsule with body flaps resulting in a lift to drag of 0.52. The Delta Clipper SSTO RLV was technically a lifting body, since it was to have four body flaps. The biconic capsule favored by some people for missions to Mars is technially a lifting body and only has a lift to drag of 0.6. The Lockheed-Martin CEV lifting body only has a lift to drag of 1.0.<br /><br />Most of the low lift to drag lifting body designs do so to aid reentry heating and g force issues. That is an important consideration for deep space missions as opposed to LEO missions.<br /><br />On the other hand the goal of a reusable LEO launch vehicle has lead to lifting body designs with higher lift to drag ratios. The hope being that conventional runway landing would aid turnaround times and simplify servicing of the vehicle. That's the goal from which the 60's and 70's NASA experimental lifting body designs came from. These lifting bodies did not use fly by wire active control, they were manually landed and had a lift to drag of about 3.<br /><br />Then there is the X-38 crew return vehicle which really seems to confuse a lot of people. The X-38 was designed as an emergency escape vehicle, as such it is highly specialized and using it to draw conclusions about the entire universe of lifting bodies is very misleading. The X-38 only has an endurance of a few hours, it can't be picky about it's de-orbit burn during an emergency escape. The X-38 only has a lift to drag of about 2, the better to reduce g forces on possibly injured crew and to increase crossrange to aid finding a landing spot, i

 

[j05h]

>It was somewhere around 1967 that NASA did a <br /> />hypersonic/supersonic/subsonic wind tunnel study on an <br /> />autogyro system for the Apollo capsule that would have <br /> />allowed it to make a soft landing on the White House <br /> />lawn on its return from the Moon.<br /> />In other words, capsules aren't limited to splashing down in the ocean.<br /><br />Cool!! That is the earliest example of a "Roton" style rotor I've heard of! Obviously, with Soyuz landing on the Kazakh steppes, not all capsules do the splash-down. <br /><br />What configuration do you favor for simplicity, robustness and affordability?<br /><br />Josh <div class="Discussion_UserSignature"> <div align="center"><em>We need a first generation of pioneers.</em><br /></div> </div>

 

[spacefire]

yeah, true, there are lifting bodies and lifting bodies.<br />it's all a matter of evolution, from a simple biconical shape to the X38 (SDV) shape or HL42 or Venture Star.<br />The principle is the same: no wings, lifting reentry.<br />landing on a runway is optional, but the only option IMHO if we want to develop cheap, safe, reliable access to orbit. <div class="Discussion_UserSignature"> <p>http://asteroid-invasion.blogspot.com</p><p>http://www.solvengineer.com/asteroid-invasion.html </p><p> </p> </div>

 

[john_316]

They can go capsule or the x-38/x-37 design if they like but i dont care...<br /><br />Just get it done and get it done right....<br />

 

[mrmorris]

<font color="yellow">"I'd say capsule with steerable parafoil, skid landing... basically no extra added weight and slight increase in complexity. "</font><br /><br />The X-38 parafoil was over 12% of the landing weight. By contrast, the Apollo parachute system was less than 3%. Parafoils are significantly more complicated, larger, and heavier than a parachute with an equivalent capacity.

 

[kane007]

And what happens if a critical component fails to reach orbit?

 

[john_316]

I think a Capsule or Lifting Body on a second stage of a SRB designed rocket would do just fine for ISS and LEO operations.<br /><br />A SRB derived cargo carrier with a 5 segment SRB and either a single SSME or twin J2S engines might be also good enough to deliver any other ISS components under 30 MT to the ISS if you ask me.<br /><br />But I think they should go ahead and start moving ISS assembly flights to Atlas or Delta here soon. That way they can do as little as possible with the STS and retire them on time or early.<br /><br />Delta Heavy or Atlas Heavy I think can manage the further ISS assembly flights if they start prepping some of them now instead of delaying them for Shuttle flights. That would also probably save money too as not all of the money would goto the STS system and what saving there are could goto CEV production.<br /><br />Any idea or suggestions on this???<br /><br />Also an enlarged X-38 with a propulsion stage is just as fine as a capsule is if you ask me. Honestly to me either one will work out just fine.<br /><br /><img src="/images/icons/wink.gif" /><br />

 

[najab]

The problem with moving ISS components to another launch vehicle is that they have been designed, tested and certified for the conditions inside the Shuttle payload bay - accoustics, vibration, acceleration, attachment points, etc - so they would have to be <b>re</b>designed for EELVs, which may well be quite expensive.

 

[tomnackid]

The X-38 parafoil was over 12% of the landing weight. By contrast, the Apollo parachute system was less than 3%. Parafoils are significantly more complicated, larger, and heavier than a parachute with an equivalent capacity. <br />-------------------------------------------------------------------------------------------<br /><br />How does a Rogallo parawing compare to a parachute and a parafoil? My impression is that it can be much smaller and lighter than an equivalent parafoil. I have seen photos of skydivers using a Rogallo type chute and it looked like it was much smaller even than a traditional circular chute.