TSTO

[mlorrey]

Please feel free to do so. The secret is, that rocket science may be difficult and complicated, but ramjet science is as easy as smoking a pipe. (you can quote me on that!)<br /><br />The more people who build ramjets and get them in the air, the more people will realize that the government space program is a sham.

 

[scottb50]

SRB's produce a lot of power. They are butt simple and cheap. Once burned out the housing weight is minimal.<br /><br />What plans could I have? I'll give you my address. Will you send me money? I figuered how to do it, maybe others could help put it into play.<br /><br />As for my resources, I hope to pay next months bills.<br /> <div class="Discussion_UserSignature"> </div>

 

[tap_sa]

<font color="yellow">"Ramjets capable of supersonic flight but without any adjustable spike or nozzle geometry (i.e. built for a fixed speed) typically require 200-450 mph to ignite and generate sufficient thrust on their own. Leduc's 010 models were launched at 200 mph from the backs of WWII era bombers."</font><br /><br />Just a thought; how about mating pulsejet and ramjet? Static and slow speed thrust by pulsejet, and when speed is sufficient mechanically force the reed valve to stay open and switch to ramjet mode.<br />

 

[Swampcat]

<font color="yellow">"The unmanned suborbital versions with either be launched with the help of D/E/F grade "Estes" style rocket motors..."</font><br /><br />Just a note...Estes doesn't make F class motors, but I understand what you're getting at. A better bet would be Aerotech composite motors, but you're not talking a great deal of lift capability with those motor classes.<br /><br />Speaking of which...what is the expected mass and dimensions of your ramjet? Fuel requirements? Have you had a chance to put together a thrust curve or any other data on it? How much velocity do you need to light the ramjet? I'm a Level 1 amateur rocketeer (which means I can legally fly up to I motors) and it sounds like it would be an interesting project to design a rocket to fly a ramjet. <div class="Discussion_UserSignature"> <font size="3" color="#ff9900"><p><font size="1" color="#993300"><strong><em>------------------------------------------------------------------- </em></strong></font></p><p><font size="1" color="#993300"><strong><em>"I hold it that a little rebellion now and then is a good thing, and as necessary in the political world as storms in the physical. Unsuccessful rebellions, indeed, generally establish the encroachments on the rights of the people which have produced them. An observation of this truth should render honest republican governors so mild in their punishment of rebellions as not to discourage them too much. It is a medicine necessary for the sound health of government."</em></strong></font></p><p><font size="1" color="#993300"><strong>Thomas Jefferson</strong></font></p></font> </div>

 

[wdobner]

<i>Just a thought; how about mating pulsejet and ramjet? Static and slow speed thrust by pulsejet, and when speed is sufficient mechanically force the reed valve to stay open and switch to ramjet mode. </i><br /><br />How similar would that be to an ejector rocket/ramjet? I know a pulse-jet has a valve at the intake to prevent the air being expelled during combustion, which I'd think would be a potential liability. Does an ejector rocket use a valve at the intake to keep air from entering? The nice thing with a pulse or ramjet, scramjet, and rocket hybrid setup is that you can use just one propulsion source to get off the ground and possibly all the way into orbit. Admittedly this is well outside any basement aerospace group's abilities, and is outside the idea of a two-stage to orbit vehicle, but it's certainly worth noting simply because a ramjet is hardly as useless as some members would paint them.<br /><br />What's with the ICBM focus here? Just because SpaceX launches vertically suddenly every TSTO concept has to follow suit? What about horizontal launch systems? The Russians had that tiny spaceplane to be launched from the back of an AN225, t/Space had their air-launched concepts, and on the outside there are things like the Sanger spaceplane. If DARPA and the DOD are going to do scramjet research while not pursuing combined cycle performance like NASA was going to for a potential SSTO then why not look for ways to make <i>that</i> work for spaceflight? Take their scramjet designs, work them up to at least a Mach 15 to 20 capability, and have these spaceplanes make a suborbital path. At the peak of this path kick out a satellite with an upper stage under it to place the payload in orbit. That way we're not putting the 'heavy' wings that all you ICBM fans whine about into orbit, nor are we wasting mass on an expendible aerodynamic shroud. We don't need anything more complicated than a scaled up X-43 with a cargo bay and some workaround for low-speed fl

 

[mlorrey]

Launchers tend to be heavy things, overburdened with fuel beyond a normal aircraft (if being launched horizontally). Pulse jets and PDEs do not generate sufficient thrust (note the V-1 needed a jato and catapult to launch) to develop sufficient airspeed to take off on their own either. They have terrible T/W due to structural requirements caused by the vibration.<br /><br />The available viable options are thus:<br />a) tube launch (Bull supergun, pneumatic gas gun, submarine missile launch, Holland sub pneumatic artillery)<br />b) catapult launch (V-1 buzzbomb, UAVs, some ramjet missiles)<br />c) tow launch (Kelly Astroliner)<br />d) small turbojet augmenter (Leduc 020,021, and 022 as well as Griffon 2 used them) in the core of the ramjet to get airspeed going. This is the basis of the TBCC engine.<br />e) rocket ejector. This can be as simple as an ejectable JATO in the nozzle of the ramjet, or a full liquid fueled engine running off the ramjet fuel and MIPCC oxidizer. This is the basis of the RBCC engine.<br />f) air launch (X-7, X-43A).<br />g) separate rocket engine (BOMARC, Navajo, METEOR)<br /><br />Vertical launch is generally difficult unless your initial propulsion provides vehicle thrust to weight greater than 1:1, preferably 1.3:1 or greater.

 

[mlorrey]

I won't know the answers to some of these questions until I have it built. I could spend a lot of time doing math to predict, but those would just be predictions. I prefer to do testing on real hardware, not paper studies like NASA does.<br /><br />Mass should be around 4 lbs or less. Thrust will be around 240 lbs. Diameter: 4" Length: 19.5"<br /><br />I'm expecting to get combustion and sustainable T/W over 1:1 at 200 mph. I'd like to have the rockets push it sufficiently over that, to 300 or more to ensure sufficient thrust.<br /><br />I will be experimenting with different fuels: white gas, gasoline, various alcohols, kerosene, etc.

 

[mlorrey]

My X-106 project will be horizontal take-off.<br /><br />I'd love to spend the time to develop a true combined cycle engine (and the money), but my goal is low cost. Ramjets are very simple, very cheap to produce in quantity on an assembly line, far more so than any other engine. They are throwaway items. I plan on using them on the X-106 as underwing throwaways, so while I'd love to see a combined cycle version, at this point I'm designing toward as simple as possible while still being able to reach mach 7 or 8. So I've got an adjustable nose spike to regulate airflow. The full size versions will feature MIPCC also. I may do something with expandable nozzles, but that is something down the road. One thing at a time. KISS.<br /><br />So at this point I'm building a simple ramjet that could launch a rocket alone, or or multiple ramjets clustered around a core tank for higher performance. Beyond fuel regulation, the nose spike will gradually move forward with airspeed to increase choke. That is it, two control mechanisms.<br /><br />The ramjets I'm building now I'm planning on using on rockets because they will be targeted toward the suborbital flight regime, seeking to maximize altitude, to reach space in order to attract sounding rocket-type customers.<br /><br />Money from that will fund the HTHL X-106 program, and ramjet experience gained from the suborbital program will be used for full scale ramjets.

 

[jschaef5]

I would really have liked to see the scramjet be built that could transform in flight for the speed that it was at; act as a ramjet at slow, scramjet at faster and even close off and become a rocket.<br /><br />mlorry, are you worried at all that scramjet technology may bring some promising findings and make your entire vehcile pointless, since you could possibly do the same with a single scramjet. Although it is cool how you are using pretty much established technologies and combining them to make 1 vehicle. (atleast thats what it sounds like to me) <div class="Discussion_UserSignature"> </div>

 

[tomnackid]

It seems hard to get around the fact that a rocket engine can operate from lift-off to orbital velocity whereas you need different types of air-breathing engines for different segments of the flight regime. I think this is the reason that ramjets haven't been use more for launch vehicles, not some big government/contractor conspiracy.

 

[josh_simonson]

I'd develop a cheap, lightweight sounding rocket, perhaps with a re-useable hybrid rocket 1st stage to get it up to speed. Selling services on the sounding rocket could generate revenue for further R&D and attract investors.

 

[tap_sa]

Are Bomarc schematics declassified? Might be a good starting point <img src="/images/icons/wink.gif" />

 

[wdobner]

<i>It seems hard to get around the fact that a rocket engine can operate from lift-off to orbital velocity whereas you need different types of air-breathing engines for different segments of the flight regime.</i><br /><br />While an air breathing HOTOL SSTO may require multiple propulsion modes to reach orbit, this can very easily be done with a single engine. Combined cycle rocket/ramjet/scramjet engines aren't anything particularly new, and is simply the next step after the X-43 and X-51. A fully reusable vehicle powered by such a propulsion system would use changes in LOX flow and inlet geometry to accomodate four propulsion modes. For example a vehicle could take off with the inlet open and the LOX feed on, thus the engine would act like an ejector rocket. This does use LOX, but can do so much more efficiently than a straight rocket by burning some atmospheric oxygen, allowing for a lower LOX load. The ejector rocket would get the vehicle off the runway and up to somewhere between 200 and 300mph, at that time the LOX would cut off, the inlet geometry would shift, and it'd become a ramjet. The ramjet would run up to somewhere between Mach 3 and Mach 4, at which time a LOX feed would come on and it'd become a LOX augmented ramjet. This would hopefully run right into scramjet ignition up around Mach 6 or 7, but it's possible that a slightly higher LOX load would be required and the engine would shift over to straight liquid rocket to get up to scramjet speed. From Mach 7 to around Mach 20, a change in velocity of nearly 10,000mph, the spaceplane would act as a scramjet, obtaining all oxidizer from the surrounding atmosphere. This is likely where the greatest savings relative to a conventional rocket would come from. At around Mach 20 the vehicle would likely be too high or too fast to keep the scramjet going, so the inlet would close and it'd become a straight liquid rocket for the final 3,000 or so mph needed for orbital velocity. <br /><br />All told from

 

[mlorrey]

They are declassified. I've got photos of bomarc ramjets, they are pretty simple.<br /><br />I'm not concerned about government scramjets beating me. Firstly, anything the government does, private citizens can do 20 times cheaper. Secondly, there are material limits to airbreathing propulsion: mach 10-12, even with SHARP materials. Since ramjets can operate up to mach 7 alone, with MIPCC they should be able to reach mach 8-9 very easily.<br /><br />As I said, the ramjets get dumped once they are shut down. They are just metal tubes, not complex or expensive to reproduce, there is no economical value in trying to build them to carry up into orbit then reenter and land in one piece. Its a waste of energy, so the argument about 'dead weight' is a bad argument, since they won't be carried into space.<br /><br />The reason they are more than worth their weight is that they have the same T/W as LH2/LOX, but many times LH2's Isp, even with dense hydrocarbon fuels, because they burn atmospheric O2. Those of you who know the equations of spaceflight know how important that is. Those of you who don't bother to learn them will never understand why that is important.<br /><br />I'll try to explain it simply: Orbital speed is about mach 25. If we can fly 1/3 of that trip at an Isp of 1500-1800 sec, from mach 1-9.5, or mach 0.25-8.75, and the rest of the trip at a normal rocket Isp of 300-400, the average Isp for the whole trip will be 600-800 seconds, which is about what we'd get with a nuclear powered launcher. This allows a mass fraction and fuel load more typical of aircraft construction and airline levels of feasibility. This is the important key to cheap and frequent space travel.<br /><br />We don't need scramjets to accomplish this. Scramjets operate in a much harsher flight regime than ramjets, are a lot more finicky, and don't get as high Isp. Scramjets are one more example of NASA rocket scientists ignoring the maxim that "the perfect is the enemy of the good". Like their fixati

 

[jschaef5]

I think you are missing a huge point mlorry. The government isn't using technologies from the 1960's. They are trying to develop new technologies, for good or bad. Its research that keeps us advancing. Without the government doing research, small companies with no capital wouldn't get anywhere unless they have a billionaire funding them. I am talking about aeronautics here not the CEV. Research on materials and scramjets could someday prove that they are much more efficent than anything we have used to date, who knows. It seems like you praise all these little guys for using technologies that the government has created then you say the government is wasting money. Seems kind of funny to me. And if Burt Rutan wants to go higher and faster he will eventually get capped by materials (composites) unless they can find better ways which I am expecting them to do. <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>

 

[jschaef5]

I don't completely disagree with you though. Some companies have proven that they can get pretty far on far less money than the government uses. Scaled has done some remarkable things. There are probably many reasons why the government has to pay more. Like some contracters probably know they can get a lot from the government and such... <div class="Discussion_UserSignature"> </div>

 

[mlorrey]

That government funds research that results in technologies that are useful doesn't mean that they wouldn't have been developed without government. There are plenty of technologies the government hasn't paid for that have accelerated far faster (take the computer and software markets for example) when businesses understood there wasn't any free money coming from uncle sugar.<br /><br />It isn't government that creates the technologies: some company or university group creates it, and goes begging to uncle sugar for money to develop it, rather than going to venture capital markets where they'd have to give up some ownership of their technology.<br /><br />BTW: Scramjets were first developed in the 60's. Marquardt tried to develop it off the profits from their BOMARC contract. They didn't succeed then, but the concept has been around a long time.<br /><br />Not everybody needs a billionaire. Rutan did SS1 on $25 million, so he didn't really need Paul Allen. He could have done it with someone else, or a group of smaller VCs.<br /><br />Government is not necessary to do research.

 

[n_kitson]

<blockquote><font class="small">In reply to:</font><hr /><p>Secondly, there are material limits to airbreathing propulsion: mach 10-12<p><hr /></p></p></blockquote><br />Not really. You should read up on DARPA's FALCON program, which aims to test a Mach 19 and Mach 22 scramjet vehicle. <br /><br />I'm impressed with your ramjet project. While I think you underestimate the requirements of progressing to a flight vehicle, you're doing something about your dream, which is more than most of us.<br /><br />I remember a post I made here, saying let's all pool our different skills and build a moon probe - not one of my fellow geeks on the board showed any interest in actually doing something <img src="/images/icons/smile.gif" />

 

[Swampcat]

I'm afraid I'll have to wait until I get Level 3 certification before I can help you. I just put together a rough design just to get an idea of what it would take and it turns out to be at least an L motor to get that much mass off the ground and above 300mph. An M would probably be better considering I left out some redundancy in several systems. M class motors require Level 3 certification to legally use.<br /><br />Basically, I put together a two-stage design with the ramjet in the upper stage. I used an equivalent composite motor as a substitute for the ramjet--a Cesaroni M1060 which has a loaded weight of 15 pounds, an average thrust of 238 pounds and is 98mm in diameter and a little less than 22" long.<br /><br />Then I put together a booster stage with a 54mm motor mount tube and ran sims until I got the whole thing off the launch rail fast enough for stability and up to 440 fps velocity. The smallest motor that worked was an Aerotech L1500.<br /><br />How long before you're ready to test this thing? If you've got a year or two maybe I can be ready <img src="/images/icons/smile.gif" /><img src="/images/icons/wink.gif" />. <div class="Discussion_UserSignature"> <font size="3" color="#ff9900"><p><font size="1" color="#993300"><strong><em>------------------------------------------------------------------- </em></strong></font></p><p><font size="1" color="#993300"><strong><em>"I hold it that a little rebellion now and then is a good thing, and as necessary in the political world as storms in the physical. Unsuccessful rebellions, indeed, generally establish the encroachments on the rights of the people which have produced them. An observation of this truth should render honest republican governors so mild in their punishment of rebellions as not to discourage them too much. It is a medicine necessary for the sound health of government."</em></strong></font></p><p><font size="1" color="#993300"><strong>Thomas Jefferson</strong></font></p></font> </div>

 

[josh_simonson]

A ramscoop on top of a truck might be able to get sufficient airflow too, though you'd need a place where you could drive fast and make fireballs without getting into trouble. <br /><br />I still think an air compressor based windtunnel is the way to go though. Having a stationary testbed would allow lots of data to be collected about airspeed, thrust, fuel consumption, ect, to tweak your design. Wife permitting you could do it all in the garage too. The compressor could be recycled for use as an air cannon to boost flight prototypes too, checkout some of the pumpkin chuckin' guns for inspiration.

 

[scottb50]

I'm thinking of a much lighter structure. A composite, single piece tube with preformed propellant segments, pushed into the tubes from the rear. Segments would have a renewable ablative inner surface, send the spent segments to the reloading point and install renewed segments for the next flight. <div class="Discussion_UserSignature"> </div>

 

[Swampcat]

<font color="yellow">"A ramscoop on top of a truck might be able to get sufficient airflow too, though you'd need a place where you could drive fast and make fireballs without getting into trouble."</font><br /><br />Oh, I agree, as long as your truck can do 300mph <img src="/images/icons/smile.gif" />.<br /><br />Ground testing is always a good first method, but sooner or later you're going to have to fly. I would think that an RC airplane would make a decent test bed as well. I don't know much about that though. I <b><i>do</i></b> know a little about rockets and what I know suggests that it will take a pretty good sized booster (from the amateur prospective) to get a nearly 20 pound motor and all associated hardware up to 300mph and recovery it all safely. If it were me, I'd think about air launching it.<br /> <div class="Discussion_UserSignature"> <font size="3" color="#ff9900"><p><font size="1" color="#993300"><strong><em>------------------------------------------------------------------- </em></strong></font></p><p><font size="1" color="#993300"><strong><em>"I hold it that a little rebellion now and then is a good thing, and as necessary in the political world as storms in the physical. Unsuccessful rebellions, indeed, generally establish the encroachments on the rights of the people which have produced them. An observation of this truth should render honest republican governors so mild in their punishment of rebellions as not to discourage them too much. It is a medicine necessary for the sound health of government."</em></strong></font></p><p><font size="1" color="#993300"><strong>Thomas Jefferson</strong></font></p></font> </div>

 

[mlorrey]

"Not really. You should read up on DARPA's FALCON program, which aims to test a Mach 19 and Mach 22 scramjet vehicle. "<br /><br />The key is where they'll be doing those speeds at. Will they be doing mach 19 at 150,000 feet where the air is breathable? No, they won't. Their scramjet will be in rocket mode at that point and at a much higher altitude. I aim for the X-106 to reach those speeds and higher in rocket mode as well.<br /><br />SHARP materials can handle mach 11 at 100,000 feet, maybe mach 13 at 150,000 feet. That is the upper limit of air breathing. While hydrogen scramjets could get as high as mach 19 before their Isp drops down to rocket levels, the aerodynamic drag of carrying massivy LH2 tanks will cause serious performance losses and the costs of meeting this goal by investing vast sums in new materials technologies that are untested (shades of STS silica bricks all over again) will be significantly greater than the cost for me do do what I set out to do. As a result, I will beat the scramjet in the payload market with lower prices. The perfect is the enemy of the good. Ignore the 80/20 rule at your peril.

 

[n_kitson]

<blockquote><font class="small">In reply to:</font><hr /><p>Their scramjet will be in rocket mode at that point and at a much higher altitude.<p><hr /></p></p></blockquote><br />How can an airbreathing engine be "in rocket mode"?

 

[tap_sa]

RBCC? Close the inlet, start pumping in oxidizer too -> scramjet turns into rocket engine.