Rocket Powered Blimps?

[BrianSlee]

<p>A story in the NY Times today talks to some of the other applications of the technology and&nbsp;also discusses some of the drawbacks of current designs.</p><p>http://www.nytimes.com/2008/07/05/business/worldbusiness/05dirigible.html?pagewanted=1&th&emc=th</p> <div class="Discussion_UserSignature"> <p> </p><p>"I am therefore I think" </p><p>"The only thing "I HAVE TO DO!!" is die, in everything else I have freewill" Brian P. Slee</p> </div>

 

[aphh]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>A story in the NY Times today talks to some of the other applications of the technology and&nbsp;also discusses some of the drawbacks of current designs.http://www.nytimes.com/2008/07/05/business/worldbusiness/05dirigible.html?pagewanted=1&th&emc=th <br /> Posted by BrianSlee</DIV></p><p>Has there ever been an attempt to combine aerodynamic lift with LTA? Small wings on a more aerodynamically shaped blimp?&nbsp;</p>

 

[BrianSlee]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Has there ever been an attempt to combine aerodynamic lift with LTA? Small wings on a more aerodynamically shaped blimp?&nbsp; <br />Posted by aphh</DIV><br /><br />DARPA funded Lockheed to build the Skycat, which was&nbsp;part of a&nbsp;development program to provide DoD with a heavy lift capability.&nbsp; Read more here</p><p>http://en.wikipedia.org/wiki/Skycat</p><p>Skycat was defunded following what&nbsp;I believe (emphasis on believe) were successful low level handling and control tests.&nbsp; I was told by DARPA that this was a congressional decision *based on budget* and no reasons of a technical nature&nbsp;were offered upon further inquiry *which is not surprising* given the nature of the program.&nbsp;</p><p>here is some video</p><p>http://www.youtube.com/watch?v=W3n5cUaG5fg</p> <div class="Discussion_UserSignature"> <p> </p><p>"I am therefore I think" </p><p>"The only thing "I HAVE TO DO!!" is die, in everything else I have freewill" Brian P. Slee</p> </div>

 

[aphh]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>here is some videohttp://www.youtube.com/watch?v=W3n5cUaG5fg <br /> Posted by BrianSlee</DIV></p><p>Thanks for the video. It doesn't look aerodynamic at all. It looks pretty sad. I'm surprised they even did that.</p><p>Your desing with the tunnel that goes through the dirigible and houses the engines and steering looks far superior to that clumsy Lockheed design.&nbsp;</p><p>What I'd like to see is a true hybrid of a plane and a blimp. Your design could be that hybrid.&nbsp;</p>

 

[CalliArcale]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>DARPA funded Lockheed to build the Skycat, which was&nbsp;part of a&nbsp;development program to provide DoD with a heavy lift capability.&nbsp; Read more herehttp://en.wikipedia.org/wiki/SkycatSkycat was defunded following what&nbsp;I believe (emphasis on believe) were successful low level handling and control tests.&nbsp; I was told by DARPA that this was a congressional decision *based on budget* and no reasons of a technical nature&nbsp;were offered upon further inquiry *which is not surprising* given the nature of the program.&nbsp;here is some videohttp://www.youtube.com/watch?v=W3n5cUaG5fg <br /> Posted by BrianSlee</DIV></p><p>Sounds all too familiar, I'm afraid.&nbsp; Some politician saw a chance to save some money and take credit for improving the budget deficit, no doubt.&nbsp; A lot of worthy programs have been sacrificed in this manner, unfortunately.&nbsp; I hate politics.</p><p>You mentioned earlier that you would require signing a NDNC agreement before disclosing sensitive information, but that the information would be free to the government.&nbsp; That gets into an area that I do have some experience with, as I do configuration management in the defense sector.&nbsp; If your work is privately funded, be careful how you give information to the government.&nbsp; Make sure you have all of your data properly marked so that you do not end up giving away more data rights than you intended.&nbsp; You may already know all of this, but just in case you do not, I recommended reading up on the FAR and the DFARS. These discuss the nitty-gritty details of how to mark data if you are asserting limited government purpose rights.&nbsp; In theory, if you fail to mark it exactly right, you grant the government an unlimited license to your data, to do with it as they please.&nbsp; You'll still own it, legally, but they will be able to do what they want with it, including licensing one of your competitors to build it.&nbsp; (And yes, that does happen.)</p> <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[BrianSlee]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Sounds all too familiar, I'm afraid.&nbsp; Some politician saw a chance to save some money and take credit for improving the budget deficit, no doubt.&nbsp; A lot of worthy programs have been sacrificed in this manner, unfortunately.&nbsp; I hate politics.You mentioned earlier that you would require signing a NDNC agreement before disclosing sensitive information, but that the information would be free to the government.&nbsp; That gets into an area that I do have some experience with, as I do configuration management in the defense sector.&nbsp; If your work is privately funded, be careful how you give information to the government.&nbsp; Make sure you have all of your data properly marked so that you do not end up giving away more data rights than you intended.&nbsp; You may already know all of this, but just in case you do not, I recommended reading up on the FAR and the DFARS. These discuss the nitty-gritty details of how to mark data if you are asserting limited government purpose rights.&nbsp; In theory, if you fail to mark it exactly right, you grant the government an unlimited license to your data, to do with it as they please.&nbsp; You'll still own it, legally, but they will be able to do what they want with it, including licensing one of your competitors to build it.&nbsp; (And yes, that does happen.) <br />Posted by CalliArcale</DIV></p><p>CalliArcale,</p><p>&nbsp; Yes you are correct, markings for government review should always follow FAR and DFAR guidlines and requirements.&nbsp;In the new era of outsourcing I also include specific data rights for SETA contract employees (System Engineering and Technical Assistance) who already have a signed ND on file for government purpose access to sensitive data.</p> <div class="Discussion_UserSignature"> <p> </p><p>"I am therefore I think" </p><p>"The only thing "I HAVE TO DO!!" is die, in everything else I have freewill" Brian P. Slee</p> </div>

 

[CalliArcale]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>CalliArcale,&nbsp; Yes you are correct, markings for government review should always follow FAR and DFAR guidlines and requirements.&nbsp;In the new era of outsourcing I also include specific data rights for SETA contract employees (System Engineering and Technical Assistance) who already have a signed ND on file for government purpose access to sensitive data. <br /> Posted by BrianSlee</DIV></p><p>Cool.&nbsp; &nbsp; You already know this stuff.</p><p>I'm kinda out of my depth on whether or nor a rocket powered blimp would be a good idea, so I seized at the one thing I actually *do* know something about.&nbsp; <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-tongue-out.gif" border="0" alt="Tongue out" title="Tongue out" />&nbsp; I'll let everybody get back to the interesting technical discussion. </p> <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Cool.&nbsp; &nbsp; You already know this stuff.I'm kinda out of my depth on whether or nor a rocket powered blimp would be a good idea, so I seized at the one thing I actually *do* know something about.&nbsp; &nbsp; I'll let everybody get back to the interesting technical discussion. <br />Posted by CalliArcale</DIV></p><p>If you would a real eye opener pick a large development contract then check the boiler plate for the <strong>authorization clause.&nbsp; <br /></strong></p> <div class="Discussion_UserSignature"> </div>

 

[keermalec]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'></p><p>so for the same rocket launched from ground level it would mean a 28%&nbsp;increase in payload of 13570.32 Kg</p><p>If I have not erred in my math. I am sure someone will&nbsp; let me know.</p><p> <br /> Posted by BrianSlee</DIV></p><p>Hi BrianSlee, now I understand your idea. I believe there are two possible ways to go from 80'000 feet to orbit using your airship.</p><p>1. Launch a rocket at 80'000 ft with the 28% mass savings you indicate. Incidentally, the 13.6 ton difference in end mass for the same 454'000 kg rocket launched from sea-level, equates to much more than a 28% increase in useful payload. Useful payload from sea-level is about 2.5% of GLOW or 11.4 tons. Launching the same rocket from 80'000 ft will raise the useful payload to 11.4 + 13.6 = 25 tons, or a a 119% increase. </p><p>2. Continue thrusting your lifting body-shaped airship to gain altitude and velocity. If high-altitude, low-thrust systems are used (such as a small ramjet for 20-100'000 feet and an ion-drive for 100'000 feet to orbit) maybe you can pass the critical performance point where your gain in velocity allows you to lift ever higher where air drag is ever smaller. If you manage to accelerate all the way to 7.9 km/s then you're in space. </p><p>&nbsp;</p><p>&nbsp;</p> <div class="Discussion_UserSignature"> <p><em>“An error does not become a mistake until you refuse to correct it.” John F. Kennedy</em></p> </div>

 

[BrianSlee]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Hi BrianSlee, now I understand your idea. I believe there are two possible ways to go from 80'000 feet to orbit using your airship.1. Launch a rocket at 80'000 ft with the 28% mass savings you indicate. Incidentally, the 13.6 ton difference in end mass for the same 454'000 kg rocket launched from sea-level, equates to much more than a 28% increase in useful payload. Useful payload from sea-level is about 2.5% of GLOW or 11.4 tons. Launching the same rocket from 80'000 ft will raise the useful payload to 11.4 + 13.6 = 25 tons, or a a 119% increase. </DIV></p><p>&nbsp;keermalec,</p><p>You are correct.&nbsp; The increase in mass fraction would represent a much higher percentage in usable payload.&nbsp; Of course some of the increase would probably&nbsp; be taken up by&nbsp;increases in&nbsp;structural weight&nbsp;to accomodate the&nbsp;larger payloads. &nbsp;You are also correct in your statement of size, it will be massive in volume, comparable to some of the largest architectural structures ever built.</p><p>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>2. Continue thrusting your lifting body-shaped airship to gain altitude and velocity. If high-altitude, low-thrust systems are used (such as a small ramjet for 20-100'000 feet and an ion-drive for 100'000 feet to orbit) maybe you can pass the critical performance point where your gain in velocity allows you to lift ever higher where air drag is ever smaller. If you manage to accelerate all the way to 7.9 km/s then you're in space. &nbsp;&nbsp; <br />Posted by keermalec</DIV></p><p>I have looked at incorporating ION propulsion for final ascent and I don't think that it will work right now.&nbsp; Even with the much higher ISP that ION propulsion provides I just don't think that it will provide enough thrust to overcome the drag forces involved.&nbsp; But I still haven't ruled it out completely.&nbsp; I would need&nbsp;a lot more data for a feasability study in that area and I believe it would require developing a whole new ION propulsion system.&nbsp; I am trying to work with off the shelf components as much as possible.&nbsp; For an SSTO version I believe I can attain an altitude of 180,000 ft before the CVC (Constant Volume Combustion) ramjet component loses effective thrust and is discarded as a consumable to shed mass for final ascent.&nbsp; And you are spot on in your assesment of the fact that its all about getting beyond the tipping points for critical performance parameters to enable SSTO operation.&nbsp; My guess right now is that the system would probably not remain in LEO very long (maybe not even a complete orbit) but would release the payload desired at speed and altitude then return to atmospheric operation for recovery and reload. </p> <div class="Discussion_UserSignature"> <p> </p><p>"I am therefore I think" </p><p>"The only thing "I HAVE TO DO!!" is die, in everything else I have freewill" Brian P. Slee</p> </div>

 

[BrianSlee]

One bump for good measure<br /> <div class="Discussion_UserSignature"> <p> </p><p>"I am therefore I think" </p><p>"The only thing "I HAVE TO DO!!" is die, in everything else I have freewill" Brian P. Slee</p> </div>

 

[BrianSlee]

<p>bump again for LTABS post.</p> <div class="Discussion_UserSignature"> <p> </p><p>"I am therefore I think" </p><p>"The only thing "I HAVE TO DO!!" is die, in everything else I have freewill" Brian P. Slee</p> </div>

 

[BrianSlee]

<p>here is a rough math model for review.&nbsp; This is a simple model, but I think it demonstrates the concept well enough.&nbsp; As always all comments are welcome.</p><p>&nbsp;</p><p>http://www.escape-velocity.biz/Model.html</p> <div class="Discussion_UserSignature"> <p> </p><p>"I am therefore I think" </p><p>"The only thing "I HAVE TO DO!!" is die, in everything else I have freewill" Brian P. Slee</p> </div>

 

[BrianSlee]

<p>Have you given up on the debate?&nbsp; I even brought some math just for you <img src="http://sitelife.space.com/ver1.0/content/scripts/tinymce/plugins/emotions/images/smiley-wink.gif" border="0" alt="Wink" title="Wink" /></p> <div class="Discussion_UserSignature"> <p> </p><p>"I am therefore I think" </p><p>"The only thing "I HAVE TO DO!!" is die, in everything else I have freewill" Brian P. Slee</p> </div>

 

[MeteorWayne]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Have you given up on the debate?&nbsp; I even brought some math just for you <br />Posted by BrianSlee</DIV><br /><br />Yes, I think the fact that no one has replied in 2 months indicated you are tilting at windmills </p><p>Since then you have talking to yourself....</p> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[BrianSlee]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Yes, I think the fact that no one has replied in 2 months indicated you are tilting at windmills Since then you have talking to yourself.... <br />Posted by MeteorWayne</DIV><br /><br />Don Quixote is one of my personal heroes ;O)</p><p>as far as windmills....take a look at the math model and the results.&nbsp; I don't see anything in the current inventory or on the horizon to match its potential capability.</p> <div class="Discussion_UserSignature"> <p> </p><p>"I am therefore I think" </p><p>"The only thing "I HAVE TO DO!!" is die, in everything else I have freewill" Brian P. Slee</p> </div>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Don Quixote is one of my personal heroes ;O)as far as windmills....take a look at the math model and the results.&nbsp; I don't see anything in the current inventory or on the horizon to match its potential capability. <br />Posted by BrianSlee</DIV></p><p>That is not a math model or results.&nbsp; It is a spreadsheet with a mass of questinable assumptions and zero supporting data.&nbsp; GIGO. </p><p>Why does your z acceleration and velocity turn negative for part of the trajecory?<br /></p> <div class="Discussion_UserSignature"> </div>

 

[BrianSlee]

Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>That is not a math model or results.&nbsp; It is a spreadsheet with a mass of questinable assumptions and zero supporting data.&nbsp; GIGO. Why does your z acceleration and velocity turn negative for part of the trajecory? <br />Posted by DrRocket</DIV><br /><br />As I said it is a rough model.&nbsp; I still need to include compressible flow characteristics for speeds in excess of 300&nbsp;m/s&nbsp; And actual CL and CD numbers will require wind tunnel testing.&nbsp;CD is based on known values for&nbsp;certain&nbsp;geometries and the CL&nbsp;is based on the Kutta-Joukowski analysis,&nbsp;I believe the average ISP for air breathing operation to be a conservative estimate.&nbsp; The oscillations in the z axis are caused by the effects of change in buoyancy *vs change in lift* as altitude increases. <div class="Discussion_UserSignature"> <p> </p><p>"I am therefore I think" </p><p>"The only thing "I HAVE TO DO!!" is die, in everything else I have freewill" Brian P. Slee</p> </div>

 

[kelvinzero]

<p>Something that occured to me after hearing about that other idea of a blimp reaching orbit (not this idea)</p><p>The main argument against it was that the air resistance would be too great. It occured to me that an open ended sleeve of sufficient length could also act&nbsp;like a hot air balloon while having much less air resistance. If hot air was created at the front of the sleeve and the sleeve was moving forwards then the hot air would travel the entire length before escaping. You might need to build it pretty long to exploit this but the extra scale gives you proportionally &nbsp;extra cargo capacity and power recieving surface (supposing it uses some sort of&nbsp;beamed or solar&nbsp;power)</p>

 

[BrianSlee]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Something that occured to me after hearing about that other idea of a blimp reaching orbit (not this idea)The main argument against it was that the air resistance would be too great. It occured to me that an open ended sleeve of sufficient length could also act&nbsp;like a hot air balloon while having much less air resistance. If hot air was created at the front of the sleeve and the sleeve was moving forwards then the hot air would travel the entire length before escaping. You might need to build it pretty long to exploit this but the extra scale gives you proportionally &nbsp;extra cargo capacity and power recieving surface (supposing it uses some sort of&nbsp;beamed or solar&nbsp;power) <br />Posted by kelvinzero</DIV><br /><br />Kelvin,</p><p>&nbsp; The drag component of the force vector is a huge consideration for any craft of the size necessary to take advantage of buoyancy.&nbsp; I am not familiar with the other blimp idea.&nbsp; Is there a thread you can refer me to?&nbsp; What you are describing sounds&nbsp;like a ramjet with a beamed power source for fuel to heat the atmospheric gases.&nbsp; I believe this is similar in principle to&nbsp;the project that NASA has working on except their idea uses a cone shaped vehicle,&nbsp; </p><p>http://genesismission.jpl.nasa.gov/educate/scimodule/LaunchPropulsion/L&P_PDFs/C6_TTpropulsion.pdf</p> <div class="Discussion_UserSignature"> <p> </p><p>"I am therefore I think" </p><p>"The only thing "I HAVE TO DO!!" is die, in everything else I have freewill" Brian P. Slee</p> </div>

 

[DrRocket]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>As I said it is a rough model.&nbsp; I still need to include compressible flow characteristics for speeds in excess of 300&nbsp;m/s&nbsp; And actual CL and CD numbers will require wind tunnel testing.&nbsp;CD is based on known values for&nbsp;certain&nbsp;geometries and the CL&nbsp;is based on the Kutta-Joukowski analysis,&nbsp;I believe the average ISP for air breathing operation to be a conservative estimate.&nbsp; The oscillations in the z axis are caused by the effects of change in buoyancy *vs change in lift* as altitude increases. <br />Posted by BrianSlee</DIV></p><p>In order to drive the velocity in the z direction negative you would need the buoyancy or lift or both to be negative.&nbsp; That seems a bit odd unless there is a very unusual angle of attack.&nbsp; I would have expected the buoyancy and lift to change with altitude (and speed) but not to become negative.</p><p>I&nbsp;presume that you are using the&nbsp;Kutta-Joukowski theorem to determine the lift on the relatively stubby wings that show in the picture of the vehicle on your web site.&nbsp;&nbsp;It applies to a right cylinder (not necessarily circular in cross-section) moving transverse to the axis of the cylinder.&nbsp; I don't see&nbsp; how you are applying it to your vehicle, since the wings.&nbsp;from the illustration would seem to be poorly modeled as a right cylnder.&nbsp; I assume that you are not applying the theorem to the cylindrical body of the vehicle since&nbsp;I would have expected the velocity vector to be roughly in line with the axis of the cylinder.&nbsp; To apply the Kutta-Jukowski theorem to the "fuselage" you would need to be flying sideways, and in any case there would be no lift on right circular cylinder.&nbsp;</p><p>http://en.wikipedia.org/wiki/Kutta-Joukowski_theorem</p><p>http://en.wikipedia.org/wiki/Kutta_condition</p> <div class="Discussion_UserSignature"> </div>

 

[kelvinzero]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>Kelvin,&nbsp; The drag component of the force vector is a huge consideration for any craft of the size necessary to take advantage of buoyancy.&nbsp; I am not familiar with the other blimp idea.&nbsp; Is there a thread you can refer me to?&nbsp; What you are describing sounds&nbsp;like a ramjet with a beamed power source for fuel to heat the atmospheric gases.&nbsp; I believe this is similar in principle to&nbsp;the project that NASA has working on except their idea uses a cone shaped vehicle,&nbsp; http://genesismission.jpl.nasa.gov/educate/scimodule/LaunchPropulsion/L&P_PDFs/C6_TTpropulsion.pdf <br />Posted by BrianSlee</DIV></p><p>I skimmed that link but it seemed to be talking about all sorts of things, none of them similar.</p><p>here is a link to the 'other' idea. most people just say it is not going to work. too much friction. http://www.jpaerospace.com/&nbsp;</p><p>Yes, perhaps this thing might be like a very large beamed power ram jet, perhaps an ionocraft approach: http://en.wikipedia.org/wiki/Ionocraft&nbsp;but that isnt important.</p><p>My only potentially interesting point was that a large open ended sleeve filled with hot air would also exhibit bouancy if the hot air was continually replenished eg by whatever method provided thrust. However it would have much lower drag than a zeppelin because it doesnt need to push air out of the way.<br /></p>

 

[BrianSlee]

<p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="3"><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>In order to drive the velocity in the z direction negative you would need the buoyancy or lift or both to be negative.&nbsp; That seems a bit odd unless there is a very unusual angle of attack.&nbsp; I would have expected the buoyancy and lift to change with altitude (and speed) but not to become negative.</font></p><font face="Times New Roman" size="3">&nbsp;</font> <p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="3">In the case (plot) presented total lift is a function of the summation of the buoyant force and the lift force. <span>&nbsp;</span>As altitude is increasing the buoyant force is decreasing faster than the lift is increasing to compensate, at these points *acceleration&nbsp;Z&nbsp;is already negative with respect to Lift*&nbsp;so when the buoyant force decreases it results in an overall negative value in acceleration until increased velocity compensates. <span>&nbsp;</span><span>&nbsp;</span>Since this is a rough model, I did not consider it worthwhile to go through the current model iteration by iteration to account for the difference by adjusting AoA and velocity through application of additional thrust to remove the slight oscillations present at the output.<span>&nbsp; </span>As the model is refined and the fidelity is increased, operation will have to account for this effect.</font></p><font face="Times New Roman" size="3">&nbsp;</font> <p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="3">Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I&nbsp;presume that you are using the&nbsp;Kutta-Joukowski theorem to determine the lift on the relatively stubby wings that show in the picture of the vehicle on your web site.&nbsp;&nbsp;It applies to a right cylinder (not necessarily circular in cross-section) moving transverse to the axis of the cylinder.&nbsp; I don't see&nbsp; how you are applying it to your vehicle, since the wings.&nbsp;from the illustration would seem to be poorly modeled as a right cylnder.&nbsp; I assume that you are not applying the theorem to the cylindrical body of the vehicle since&nbsp;I would have expected the velocity vector to be roughly in line with the axis of the cylinder.&nbsp; To apply the Kutta-Jukowski theorem to the "fuselage" you would need to be flying sideways, and in any case there would be no lift on right circular cylinder.&nbsp;http://en.wikipedia.org/wiki/Kutta-Joukowski_theoremhttp://en.wikipedia.org/wiki/Kutta_condition <br />Posted by DrRocket</DIV></font></p><font face="Times New Roman" size="3">&nbsp;</font> <p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="3">The CL is based on a symmetric Jukowski airfoil with no camber and of minimal thickness along the chord line, i.e. the model applies the CL for a flat plate, and derives its output based on the wing area, AoA, velocity and atmospheric density. <span>&nbsp;</span>I would recommend not getting too hung up on trying to apply the model results to the current airframe geometry as I expect the geometry to change somewhat based on the results of the refined model. <span>&nbsp;</span>Hopefully we can agree that airplanes fly and that aerodynamic equations are scaleable in this case (I haven&rsquo;t come across any postulates or theories that state that the equations change as a result of scale) and that it reduces to a question of of whether or not it is actually producible at a low enough weight to make it usable for the purpose stated. As we now have access to university R&D facilities and computers we will be refining the airframe geometry and validating whether or not the airframe can be produced given the state of current materials and technologies.</font></p> <div class="Discussion_UserSignature"> <p> </p><p>"I am therefore I think" </p><p>"The only thing "I HAVE TO DO!!" is die, in everything else I have freewill" Brian P. Slee</p> </div>

 

[BrianSlee]

<p><BR/>Replying to:<BR/><DIV CLASS='Discussion_PostQuote'>I skimmed that link but it seemed to be talking about all sorts of things, none of them similar.here is a link to the 'other' idea. most people just say it is not going to work. too much friction. http://www.jpaerospace.com/Yes, perhaps this thing might be like a very large beamed power ram jet, perhaps an ionocraft approach: http://en.wikipedia.org/wiki/Ionocraftbut that isnt important.My only potentially interesting point was that a large open ended sleeve filled with hot air would also exhibit bouancy if the hot air was continually replenished eg by whatever method provided thrust. However it would have much lower drag than a zeppelin because it doesnt need to push air out of the way. <br />Posted by kelvinzero</DIV><br /><br />Kelvinzero</p><p>Actually I am familiar with J.P. and his efforts.&nbsp; I love their pongsat program I think it is a great educational tool.</p> <div class="Discussion_UserSignature"> <p> </p><p>"I am therefore I think" </p><p>"The only thing "I HAVE TO DO!!" is die, in everything else I have freewill" Brian P. Slee</p> </div>