World First Supersonic LTA aircraft

[lippischh]

Hi,

The idea of a supersonic lighter than air aircraft or aerostat came to me years ago, since it was something never done or even thought before, at least that's according to what i know.
the first design was quite similar to lifting bodies and was manned, after a while i reshaped it to what you can see in the attachment a long and slim unmanned aircraft similar to Sears-Haack body, it is powered by a precooled jet engine. the lift is provided by buoyancy but also two trapezoidal wings that was found effective for high speeds.

more details on the technical features of this aircraft will be here soon, and also a certain story around it.

Please share your opinions and critics it will help the project.

 

[Kryptid]

When I was kid, I thought up a supersonic blimp myself.

Doing something like this would be very difficult. In order to become buoyant, large amounts of gas would be needed. This results in a very large "fuselage" volume which in turn leads to high drag. In order to overcome the drag, powerful engines would be needed. Powerful engines would be heavy and require large amounts of fuel. These factors increase the weight which would require even more buoyancy.

 

[lippischh]

Your analysis is in fact right, but :
First we can use a longer but not bigger fuselage and that's the main principle of sears-haack body, precooled jet could give a lot of thrust, composite materials are light and very powerful, when it comes to buoancy lift i thought about using more vaccum than gas, solid balloons with a certain studied shape inside the fuselage are filled with a little amount of gas that causes a lot of pressure from outside but i think that there is a structural solution to that.

Finally sir with all my respect, there's a lot of people on this planet, so they can easily think up the same thing, but thinking doesn't mean researching possible technical solutions to achieve this thought.

i really enjoyed your critic

Regards

 

[Kryptid]

I'm pretty sure vacuum lift has been studied and demonstrated as unworkable. The "balloon" would have to be reinforced to prevent the higher external pressure from crushing it. That adds even more weight and, if a pure vacuum is used, it will be too heavy to fly at all. If I'm not mistaken, making an object longer for the same volume tends to make it heavier as well (it would have a higher surface area to volume ratio and would therefore contain more structural materials).

You should probably do some basic calculations to see where you stand. Figure out the volume of the balloon and determine how much lifting force it would have from that. Then see if you can find some way to add jet engines, fuel, structural elements, a cockpit, etc. without making the weight exceed the lifting force. Jet engine and fuel weight is easily enough to calculate at least.

 

[Stargazer]

Perhaps a rigid airship could be considered, but I can't see a supersonic blimp as very plausible myself. Of course I'd be pleased to be proven wrong...

 

[lippischh]

Hi everyone,

thanks Kryptid and Stargazer for your comments. i'll study myself the possibility of a vaccum or pseudo vaccum balloons, then i'll surely do some basic calculations to see what are the problems then find out solutions to them.

i'll post progressively the results of my study here of course, i really believe in this project and again Kryptid you're helping a lot thanks.

Regards

 

[lippischh]

Hi everyone,

First, i want to clearify how my researches will be organized, they'll be on three major axes :

1/ weight calculations of the aircraft considering that the balloon is filled with Helium gas.

2/ the design of a vaccum balloon, to find out the optimal shape and material for such a balloon to not to collapse due to the atmospheric pressure.

3/ find other solutions to achieve a more powerful buoyancy lift.

Well, i haven't found yet enough time to complete the first calculations, but here is an idea i had, it concerns a new way to achieve a more powerful buoyancy lift using either vaccum and a certain amount of gas :

here in the figure 1 you can a representation of a balloon filled with helium, the balloon doesn't collapse because the helium exert a force from the inside that hold in face of the outside force of the atmospheric pressure, now we could make things a bit simpler the only part of the helium gas that prevent the balloon from collapsing is the gas which is in contact with the interior face of the balloon so we just need it, in fig 2 you see an application for that observation we can have a vaccum inside and some helium gas with contact with the interior face of the balloon, now you may ask how can we achieve such an arrangement.

i have in mind a lot of solutions but here is the most workable : the centrifugal force; by creating a vortex inside a cylindrical or toroidal balloon the centrifugal force will oblige the little amount of helium that we've filled inside the balloon (in some special circonstances) to go with contact of the interior face of the balloon and to stay there, in addition to this the centrifugal force of the helium gas acts inside the balloon to counter the atmospheric pressure even more. see fig 3

now i know this is energy consuming, but i think that we can get enough centrifugal force with not much energy then we can take it from the jet engine(s) we are using, two fans inside the a cylindrical balloon would be a nice way, then the helium is quite light so those fans won't have a lot of drag.

this idea came to me yesterday night, i wish that you like it.

 

[hesham]

A similar old idea,

jet-ship.

http://www.secretprojects.co.uk/forum/index.php/topic,2504.30.html

 

[aam641]

Perhaps you should look more closely on engines and aerodynamic drag. Complete vacuum increases the lift by only 16% compared to helium, which is not much.

 

[Orionblamblam]

this idea came to me yesterday night, i wish that you like it.

Well... no. Put simply, it appears that you do not understand the magnitude of the forces involved, nor the mass of the systems required to counter them.

Start with your "centrifugal helium" idea: assume you want your vacuum airship to float at sea level. That's an atmospheric pressure of 14.7 pounds per square inch, covering every square inch of your cylindrical vacuum "bag." To effectively counter that with spinning helium, your helium need to exert an outward force of 14.7 pounds per square inch. Well, let's make up some numbers. For starters, assume that your helium layer is one foot thick. At standard conditions, helium has a density of about 0.000006452 pounds/cubic inch. So, your one foot thick layer of helium has a weight/area of 0.0000774 pounds per square inch. To generate centripital forces of 14.7 pounds/square inch using a gas that exerts a static weight of 0.0000774 pounds per square inch, you'll need to increase the "weight" of the gas via centrifugal force by a factor of 14.7/0.0000774 = 189,864 g's. So if we assume that your airship has a diameter of 50 feet, to determine the velocity of the gas use the equation a=v^2/r. "a" is the acceleration = 32.2 ft/sec^2 * 189864 = 6,113,608 ft/sec^2. "r" is the radius of 25 feet. So velocity of the gas works out to 12,362 feet per second, or about Mach 11.

You go ahead and try to market this. If you find any government agencies or venture capitalists who actually stake you some cash, be sure to let me know... I've got some ideas for perpetual motion machines that I think I can use to squeeze some money out of those chumps.

 

[Justo Miranda]

The vacuum airship of Francisco de Lana here , a secret project of 1670

 

[Avimimus]

Wouldn't be simpler to just have an adjustable volume airship?

Collapse the gas volume as lift increase from forward speed! Convert from being a blimp (at low speed, expanded) to a rigid airship (during the transition) and then a lifting body (at high speed)?

Anyone know of concepts like this? It might work better at some scales than others (eg. a small UAV vs. a transport aircraft). Air is very viscous for small objects and the relative strength of materials is greater.

 

[Kryptid]

Avimimus, I like that idea, (assuming the weight penalty from mechanizations wouldn't be too high). If you're just bound and determined to get an airship supersonic, that sounds like a good way to go (since it would dramatically reduce drag at high speeds).

I once had an idea to achieve extra lift myself, which was more-or-less a reworking of the hot-air balloon principle. Have a balloon made with some kind of high temperature rubber or other elastic substance. Hook it up to a pump which can fill it with air from the outside but can also close it off to the outside atmosphere. Once the balloon contains some set amount of air that gives it a spherical shape, a heating element placed on a pole in the center of the balloon will begin to heat the air within the balloon up. Heating a gas causes it to expand, reducing its density and increasing its volume. The heated air inside of the balloon becomes less dense as the balloon expands, providing positive buoyancy. Tiny fragments of aerogel might be imbedded into the rubber to improve insulation and therefore minimize energy requirements to keep the air warm. There are two advantages to this: (1) you can use the readily-available air all around you as the lifting agent instead of hydrogen or helium and (2) buoyancy can be controlled by adjusting the temparture and/or opening vents temporarily to mix the outside cooler air with the internal warmer air. One of the disadvantages to the design is that it requires power input in order to achieve buoyancy whereas a helium balloon does not. Another disadvantage is that if the heating element burns out, the buoyancy will be lost and the ship will begin to fall.

A variant on the idea would be to use the same configuration to heat a balloon filled with helium gas. This would provide more lift than an equal volume of air heated to the same temperature. Also, it could be arranged to safely descend in case of heating element failure; have just enough helium in the balloon such that its buoyancy at ambient temperatures is slightly less than the ship's weight. The balloon could then descend at a low enough rate to avoid damage once it lands.

 

[lippischh]

Hi everyone,

well, i cannot say that im happy with the critics but i want to tell all of you that all of you guys are right :

Hesham : well the idea isn't quite similar...
AdamF : this is a good idea, spending that much of energy for just 16% of lift increase....
Orionblamblam : well, really thanks for your calculations, Mach11 is too much i assume... , but in the other hand the centrifugal force isn't obliged to equal the atmospheric pressure the cylinder balloon may resist to a certain exterior force, and then we can use another heavier gas that will produce more centrifugal force with less velocity. even then i don't think it will decrease to an acceptable value, but we don't know
Justo Miranda : thanks for the illustration
Avimimus and kryptid : those are great ideas..... but in Kryptid's one i don't see what's new.

now, i will start the real calculations and i'll abandon the vaccum lift for a moment, i think there's another way to stick that helium gas to the balloon interior.
The first illustration was more artistic than technical based design so in next replies you'll see other proposals.

Regards and again thank you all

 

[Orionblamblam]

Orionblamblam : well, really thanks for your calculations, Mach11 is too much i assume... , but in the other hand the centrifugal force isn't obliged to equal the atmospheric pressure the cylinder balloon may resist to a certain exterior force

Not much. Resisting internal pressure is easy... the material is in tension. Soda/beer cans are made out of remarkably thin aluminum, for instance. A full, unopened can can be stood upon, even jumped up and down upon, and will just sit there and take it. But the moment you release the internal pressure, the slightest exterior pressure will instantly crush it.

and then we can use another heavier gas that will produce more centrifugal force with less velocity.

Wouldn't make much difference.

Any "vacuum airship" will have to have a structurally braced envelope. The structure could be internal bracing, external bracing, or by way of a remarkably strong envelope... *perhaps* something like a rigid foam of some considerable thickness. *Perhaps* something like the "airmat" inflatable structure used by the Goodyear Inflatoplanes could be formed into a *very* high pressure inflatable vacuum chamber.

Hmm. This latter one... if I've got the physics right in my head, calculating the amout of pressure needed in an inflatable vacuum chamber should be easy. If you have a cylindrical vacuum chamber 50 feet in diameter with walls 1 foot thick, that means the pressure in the walls would need to be at least 50/2 times atmospheric in order to resist crushing. 25 Atmospheres would seem potentially possible, assuming an airmat made of carbon fiber and whatnot. if the pressure exceeded 25 local atmospheres, I *think* everything would be in tension.


If you are willing to assume science fiction levels of technology, it is I suppose possible to have, say, a thin metal balloon that is kept rigid against external atmospheric pressure by some sort of powerful magnetic field.

But however it's done, it will necessarily be more heavy, complex and expensive than a simple bag full of helium or hydrogen.

 

[hole in the ground]

pure fantasy but i do love this image of an 'externally braced' vacuum airship

 

[lippischh]

i think that vaccum lift isn't very intresting for this project so i thought about something else, i've decided that the aircraft would be 100m long so it gave a volume 6 451.05 cu m for the main balloon, which give a lift of 64803.64 N so the other components weight have to not exceed 6480.3 kg that's i think not enough so what i propose then is the following flight scheme :

an external rectractable rubber balloon mounted on the back of the aircraft is filled with helium heated with the jet engine, this balloon would be big enough to rise the aircraft from the ground and ascend to a certain altitude while ascending it gains speed so aerodynamic lift with its two wings when enough aerodynamic lift reached there's no need of the external buoyancy bag, gas pumps deflates it and put some of it gas into the internal balloon and some may be thrown out, since the weight has decreased with the fuel consumption.
now the SLTA is at a speed that the buoyancy and aerodynamic lift are enough to keep it aloft it accelerates then to reach maybe a supersonic speed thanks to its long and slim shape.
now for landing, the external buyoancy bag is retracted and filled again with helium the weight of the aircraft would be less than while taking off so it descends gently to the ground.

Regards

 

[hole in the ground]

other than "because it hasnt been done" what is the intended purpose for such a vessel?

 

[Skyraider3D]

Interesting discussion you guys have going! I'll watch from the side line! ;D

That's an atmospheric pressure of 14.7 pounds per square inch.

What's that in the 21st century?

 

[Orionblamblam]

That's an atmospheric pressure of 14.7 pounds per square inch.

What's that in the 21st century?

14.7 pound/square inch = 1.0135293202e+24 yoctobar
or
14.7 pound/square inch = 2.4636708135e-23 megaparsec of mercury [0 °C]

Whichever you prefer. However, given the current state of things, it's a safe bet that the "21st century" will entail such units as:

14.7 pound/square inch = 0.0015204188 li of mercury [0 °C]

 

[Skyraider3D]

Hehe thanks for that ;D

 

[chuck4]

14.7 pound/square inch = 2.4636708135e-23 megaparsec of mercury [0 °C]

That's 24.5th century.

 

[chuck4]

Your analysis is in fact right, but :
First we can use a longer but not bigger fuselage and that's the main principle of sears-haack body, precooled jet could give a lot of thrust, composite materials are light and very powerful, when it comes to buoancy lift i thought about using more vaccum than gas, solid balloons with a certain studied shape inside the fuselage are filled with a little amount of gas that causes a lot of pressure from outside but i think that there is a structural solution to that.

Finally sir with all my respect, there's a lot of people on this planet, so they can easily think up the same thing, but thinking doesn't mean researching possible technical solutions to achieve this thought.

i really enjoyed your critic

Regards

The problem is a vacumn of a given volume (volume weight factor =0) would provide only marginally more lift in atmosphere (volume weight factor =15) than an unpressurized body of hydrogen of the same volume (volume weight factor =2), but would require much more structural weight to contain.


I suggest you look at how changes to the density of outside medium effects the viability of your idea. My hunch is the denser the outside medium, the more practical it is to make a supersonic buoyant vehicle. For example, take the super cavitation torpedo. It is really pretty close to a buoyant supersonic vehicle. It's density is in the neighborhood of its medium, so it is nearly buoyant. It is rocket propelled at several hundred knots in water, not quite supersonic for water but a good deal closer to sonic speed in its medium than any LTA blimp has ever achieved in air.


So you might very well consider a very fast, lighter than medium vehicle for atmosphere of Venus, for example,

 

[lippischh]

Thanks Skyraider for taking a look here , glad that the discussion has intrested you.

Chuck thanks for the information i didn't know about the super cavitation torpedo, and yes a lighter than medium supersonic vehicle is more practical the denser is the medium, so it would work better in water or other planet's atmosphere that is denser.

Hole in the ground achieving such an aircraft flight at supersonic speed would be pioneering in addition to that it will encourage people to have more intrest in aerostation, more project would be developed around the world for civilian, military or cargo transportation. but for me it is a challenge to be able to prove the feasibility of such an aircarft it is also a modeling exercise.

now i'm waiting for a critic for the flight scheme i described in the previous reply.

Regards

 

[Byeman]

it will encourage people to have more intrest in aerostation, more project would be developed around the world for civilian, military or cargo transportation.

Why is there a need for such interest? Unless there is a monetary gain, there doesn't need to be interest. And since there seems to be no monetary gain, there is rightfully no interest.

 

[Stargazer]

Why is there a need for such interest? Unless there is a monetary gain, there doesn't need to be interest. And since there seems to be no monetary gain, there is rightfully no interest.

To consider that only projects that generate revenue are worth pursuing is truly a sad outlook on life, I dare say.
Advancing an environment-friendly technology and encouraging its use is of interest in itself, there doesn't need to be big bucks to be made... that's what governmental agencies such as NASA should be all about, isn't it?
A supersonic airship would not necessarily be environment-friendly, for sure, but I take Hamza's remark as speaking more generally of all lighter-than-air-related projects, many of which represent a true asset from that viewpoint.

 

[lippischh]

I totally agree with you Stargazer, i meant with aerostation all the lighter than air vehicles that could be imagined, let me just take an example, ornithopter are not very intresting or revenue generating at big scales, manned but there has been a lot of attempt to build a comparable aircraft.

now i cannot see why to not develop high speed airship that could change the image of the enormous, heavy and slow blimp we all have, we can prove that airships could be efficient, practical and versatile.

 

[chuck4]

modern supersonic air breathing engine has thrust to weight ratio of about 7:1. Latest or speciality (pre-cooled) engines might do a little better, say 10:1 or 12:1. Add weight of fuel, you are back down to about 7:1. Since a vehicle is at least as heavy as it engines, the problem you encounter becomes this:


Can you design a buoyant envelope that has adaquate strength and rigidity, but whose shape and size allows it to impose no more drag at any point up to sonic speed greater than 7 times it's own weight.


With airplanes it's easy. Drags can be substantially less than its weight. But the density of an airplane is 200-500 times the density of air.


You need to produce something literally 30-70 times more voluminous than an airplane, while experience broadly similar drag characteristics, even if the structure is so efficient that it has almost weight other than engine and roughly similar Amount of fuel.

Add comparable ratio of structural wait to engine weight, And you are back to needing a volume 2 - 500 times greater, While incurjng no additional drag.

Is that realistic?

 

[Orionblamblam]

To consider that only projects that generate revenue are worth pursuing is truly a sad outlook on life, I dare say.

If you know a project is going to lose money, why would you pursue it?

Advancing an environment-friendly technology and encouraging its use is of interest in itself, there doesn't need to be big bucks to be made... that's what governmental agencies such as NASA should be all about, isn't it?

The NACA, maybe. But not NASA. Not anymore. It's a jobs program.

 

[chuck4]

The NACA, maybe. But not NASA. Not anymore. It's a jobs program.

If it was a real jobs program, it would have kept the shuttle flying. It's a program deprived of a purpose and a real budget, but which for sentimental reasons have to be kept around, sort of like a portrait of an accomplished but elderly uncle. The uncle is too senile to invite, but his illustrious past still makes one feel good about one's family.

 

[Avimimus]

To consider that only projects that generate revenue are worth pursuing is truly a sad outlook on life, I dare say.

If you know a project is going to lose money, why would you pursue it?

Research (developing techniques) or practice (especially for paper projects).

 

[Kryptid]

Oh, come on, guys! No reason a guy can't draw something up just for fun! I'm currently working on my own project.

Another thing to consider about the airship is its fineness ratio. Here is a quote from Dr. Raymer's aircraft design textbook:

Supersonic drag is typically minimized by a fineness ratio of of about 14, but that is very design dependent.

Could be a useful bit of information.

 

[Byeman]

Advancing an environment-friendly technology and encouraging its use is of interest in itself, there doesn't need to be big bucks to be made...

That would be a need and therefore revenue generating and makes my point if it were true.

But anyways, why would LTA be anymore environment-friendly than other means of transport? Hydrogen production isn't. He isn't either.

 

[Byeman]

I totally agree with you Stargazer, i meant with aerostation all the lighter than air vehicles that could be imagined, let me just take an example, ornithopter are not very intresting or revenue generating at big scales, manned but there has been a lot of attempt to build a comparable aircraft.

now i cannot see why to not develop high speed airship that could change the image of the enormous, heavy and slow blimp we all have, we can prove that airships could be efficient, practical and versatile.

You agree with Stargrazer and then say something different. Why does or should the image of the airship need to change? Changing the image does not make it nor making it high speed does not guarantee any of three: efficient, practical and versatile.

 

[chuck4]

Finess ratio of 14 is not conducive to light structural weight and high internal volume.

 

[lippischh]

Let me make myself clear this project is from the beginning for fun.

My purpose is the modelisation of a feasible supersonic LTA concept, we may argue about why to build something like that for several pages but my project is just the expression of a man imagination and thinking that are free, now chuck in your latest reply said that fineness ratio of 14 is not conductive to a high internal volume, of course but the SLTA don't need a high internal volume since the aerodynamic lift generated with it two wings would keep it aloft at high speeds substituting the external buoyancy bag lift, then at low speeds to stationary the external bag is rectracted to lift the LTA up when there's no need of fineness.

again thank you kryptid for your valuable information.

 

[chuck4]

Do you envision compressor equipment to withdraw the buoyancy gas and pressurized storage for the bouyancy gas during high speed flight? Or do you plan to simply vent the buoyancy gas once aloft, and land like an airplane on aerodynamic life?


Configuration changes will likely add a great deal of weight, unless you are also envisioning futuristic shape shifting material.

 

[lippischh]

it's a combination of the two, once at a high speed fuel would be consumed so the weight decreases,we can keep enough gas for lifting the decreased weight also we can use jet engine heat to heat the gas and gain buoyancy.

 

[lippischh]

Folks, i want a conclusion to all this.
let's recapitulate this SLTA is hypothetically the first of its type, my solutions to make it possible has been expressed during this topic, here is some specifications:
rigid airship using helium gas, the powerplant is a precooled jet engine that delivers a high amount of thrust, the materials used should be light weight and strong probably composite materials.
the flight scheme is as follows, for take-off the airship posseses a retractable buoyancy bag mounted on the back that contains helium gas heated with the jet engine, this bag would generate enough additional lift to rise the aircraft at a certain altitude, once a high altitude reached (suitable for supersonic speeds less denser air) the aircraft begin to speed up, while speeding up the bag is retracted back and the gas that was contained in it is put into the internal balloons the wings now generate enough lift to keep the aircraft aloft at this stage the aerodynamic shape of the SLTA would allow it to break the sound barrier, the aircraft slows down and the inverse process is initiated to land.
the flight scheme has not to be directly related to the model presented the same process may work for another different design.

now all your C&C are welcome
Regards