Amateur rocket to orbit

[sevenperforce]

17 minutes ago, DerekL1963 said:

1 hour ago, sevenperforce said:

Well, still, you're not really feeding it into a chamber. It is the chamber.

Well, no.  Unless the fuel tank is completely open to the chamber, which I had presumed you wouldn't do because it's monumentally stupid.

Errr...that was the geometry. It's a slow-flowing hybrid rocket, not a gel-liquid rocket.

17 minutes ago, DerekL1963 said:

HTP has disadvantages over LOX, period.   That pendulum swings both ways.

HTP has advantages over LOX for amateurs which are already in play. I was just pointing out that hypergolic action was one of several reasons to choose HTP over LOX.

[SpaceEnthusiast23]

I have a few ideas:

1. Launching from a higher point will help you make it to orbit. Watch the video from Scott Manley. He'll explain

2. You want a flight computer? Use RPi. It's pretty cheap and can be programmed. A helpful add on would be the pi in the sky. It has gps and other features that I forgot.

3. I'm not sure how this will work, but a stratolaunch systems kind of thing also might help you reach orbit.

That's it. I'm not exactly a rocket scientist, so that's all I have.

P.S. You can get contracts!

Edited July 22, 2017 by SpaceEnthusiast23

[rudi1291]

7 hours ago, SpaceEnthusiast23 said:

 

2. You want a flight computer? Use RPi. It's pretty cheap and can be programmed. A helpful add on would be the pi in the sky. It has gps and other features that I forgot.

I dont think RPi is a good idea. Its a fairly complex machine (compared to a “simple“ microcontroller) and would introduce lots of potential failure points. For critical systems it would be better to go for Arduino or some other microcontroller. As simple and robust as you can get...

[wumpus]

14 hours ago, SpaceEnthusiast23 said:

Launching from a higher point will help you make it to orbit. Watch the video from Scott Manley. He'll explain

While I suggested this near the start of the thread, the video points out that you only gain a few percent efficiency.  That said, small rockets need all the efficiency they can get.  Problems include launch permits on top of mountains, cost of strapping a rocket onto an airplane (easy if you are an air force and using small rockets.  Hard for anyone else), and shear size of payload if using weather balloon assisted launch (see theregister.co.uk's "project LOHAN").

6 hours ago, rudi1291 said:

I dont think RPi is a good idea. Its a fairly complex machine (compared to a “simple“ microcontroller) and would introduce lots of potential failure points. For critical systems it would be better to go for Arduino or some other microcontroller. As simple and robust as you can get...

Pi in the sky might be pretty necessary if you want GPS.  From memory, that appears to claim features "not allowed" in US commercial GPS systems.  Uncle Sam isn't too happy about his GPS system being used by non-US/NATO manufactured missiles.

Edited July 22, 2017 by wumpus
responded to an other quote

[rudi1291]

2 hours ago, wumpus said:

 

Pi in the sky might be pretty necessary if you want GPS.  From memory, that appears to claim features "not allowed" in US commercial GPS systems.  Uncle Sam isn't too happy about his GPS system being used by non-US/NATO manufactured missiles.

Do we need GPS? Could be handy to have it around, but i dont think its necsessary. Speed can be obtained by using an accelerometer (and appropiate programming to track acceleration starting at liftoff), attitude by using a gyroscope, heading by using a magnetometer (digital compass) and altitude by measuring ambient pressure/temperature. Probably more expensive (both time and money) than GPS, but lets us get around all the limitations and problems imposed by using a system like GPS.

[monophonic]

On 7/22/2017 at 8:07 PM, rudi1291 said:

Do we need GPS?

More like do you save enough by having GPS? It does not give attitude for starters. Sure you can approximate it from successive locations but the latency will be too high to properly control a high acceleration rocket, and you still won't get roll angle from it. Which is kinda important if you want to know which way your turn command will turn the rocket.

So you absolutely need one gyroscope at least, and preferably three. GPS possibly could replace the accelerometers, but for that you need a special low latency chip. You'll need an ITAR clearance too to source one that does not have any pesky altitude and velocity limits in its firmware. Pi in the Sky is cleared to 50km altitude, that won't cut it in an orbital rocket.

Much less paperwork to add an accelerometer and integrate your speed and distance travelled. Now you are still accumulating sideways error, especially from turning in the lower atmosphere. And wind. Just add the last two accelerometers. They work the same as the first two, just on different directions, so you'll reuse the setup.

Well who am I to say how much paperwork you are willing to go through? The electronics is not very heavy these days, although for an amateur launch the mass may still turn out significant. So is a rotation sensor+GPS setup lighter or heavier than a 6 degree of freedom inertial positioning system? That is one question you need to answer in that white paper.

Also the most accurate choice is to have both, of course. INS will serve to fix GPS's latency issues while GPS will keep INS's drift error in check.

[sevenperforce]

Useful: https://www.macrumors.com/2014/09/26/iphone-6-6-plus-two-accelerometers/

Edited July 24, 2017 by sevenperforce

[TheEpicSquared]

So, are we focusing on a HTP+napalm hybrid or an HTP+kerosene/gasoline/etc liquid? 

Or will we discuss both in the whitepaper? (Would make for quite a long paper, but I don't mind)

[cratercracker]

28 minutes ago, TheEpicSquared said:

napalm

*Vietnam Flashback*

[wumpus]

1 hour ago, TheEpicSquared said:

So, are we focusing on a HTP+napalm hybrid or an HTP+kerosene/gasoline/etc liquid? 

Or will we discuss both in the whitepaper? (Would make for quite a long paper, but I don't mind)

Napalm removes roughly half the issues of pressurizing a fuel (leaving only the HTP pressurization) and effectively serves as the combustion chamber.  I'd check* to see if it is lacking protection from boiling too fast compared to normal "rubber" hybrids, but it certainly greatly reduces the problem set.

HTP appears ideal for a white paper.  I've yet to hear an explanation on why we could obtain it when nobody else has managed it (with even more available resources).

* this is a huge problem in that it should be done to prevent wasting time obtaining HTP in the event it doesn't work.  Perhaps N20 would be sufficient to test napalm (N2O or O2 should be used at least before obtaining HTP), but eventually you will need a full up test considering it appears to be so rarely used (not sure if it has been tested outside of the tests described in "Ignition!".)

[sevenperforce]

16 minutes ago, wumpus said:

1 hour ago, TheEpicSquared said:

So, are we focusing on a HTP+napalm hybrid or an HTP+kerosene/gasoline/etc liquid? 

Or will we discuss both in the whitepaper? (Would make for quite a long paper, but I don't mind)

Napalm removes roughly half the issues of pressurizing a fuel (leaving only the HTP pressurization) and effectively serves as the combustion chamber.  I'd check* to see if it is lacking protection from boiling too fast compared to normal "rubber" hybrids, but it certainly greatly reduces the problem set.

I'm hesitant to let HTP+napalm go just yet. My earlier designs were an attempt to model a close-to-steady-state chamber design, but a more conventional hybrid design is possible as well.

The gas-tunneling problem worries me to some degree, but one positive thing is that we're dealing with more than just a pressure balance; we're also dealing with the weight of the fuel column. The rocket's acceleration will force the mass of the fuel down toward the nozzle against the combustion pressure.

Another option would be to use a lightweight annular disc wrapping around the HTP tank to push the fuel column down.

16 minutes ago, wumpus said:

HTP appears ideal for a white paper.  I've yet to hear an explanation on why we could obtain it when nobody else has managed it (with even more available resources).

* this is a huge problem in that it should be done to prevent wasting time obtaining HTP in the event it doesn't work.  Perhaps N20 would be sufficient to test napalm (N2O or O2 should be used at least before obtaining HTP), but eventually you will need a full up test considering it appears to be so rarely used (not sure if it has been tested outside of the tests described in "Ignition!".)

Other people have certainly obtained HTP.

• For jetpacks: https://www.theguardian.com/technology/2008/oct/30/aeronautics-gadgets-rocketman
• Copenhagen Suborbitals investigated using HTP to drive turbopumps: https://www.wired.com/2013/03/diy-rocket-grade-hydrogen-peroxide/
• Small monoprop peroxide rocket engines: http://www.tecaeromex.com/ingles/peroxidoi.html
• Larger monoprop peroxide rocket: http://www.rrs.org/a-hydrogen-peroxide-rocket/

 

[shynung]

@sevenperforce I'm thinking of using a reverse-bladder to solve the gas-tunneling issue; rather than encase the napalm in a bladder and have the pressurant gas compress that, we make the pressurant gas inflate a bladder which then pushes on the propellant.

[sevenperforce]

7 hours ago, shynung said:

@sevenperforce I'm thinking of using a reverse-bladder to solve the gas-tunneling issue; rather than encase the napalm in a bladder and have the pressurant gas compress that, we make the pressurant gas inflate a bladder which then pushes on the propellant.

Would still have some tendency to tunnel through. A very thin, flat plastic ring set in guide grooves would be forced down by the pressurant gas and ensure that pressure was delivered evenly across the upper face of the napalm.

[wumpus]

15 hours ago, sevenperforce said:

• For jetpacks: https://www.theguardian.com/technology/2008/oct/30/aeronautics-gadgets-rocketman
• Copenhagen Suborbitals investigated using HTP to drive turbopumps: https://www.wired.com/2013/03/diy-rocket-grade-hydrogen-peroxide/
• Small monoprop peroxide rocket engines: http://www.tecaeromex.com/ingles/peroxidoi.html
• Larger monoprop peroxide rocket: http://www.rrs.org/a-hydrogen-peroxide-rocket/

I can't take jetpacks seriously (and there is hardly room for significant fuel.  It could very well use homemade HTP).
Copenhagen Suborbitals used homemade HTP (small amounts, because this appears to be a test that wasn't followed up on.  Current engines BPM2 and BPM5 appear to use LOX and alcohol.)
Small monoprop engine used homemade HTP.
Larger monoprop engine doesn't appear to list a source, and used a few gallons in test and presumably a bit more in the launch attempt.  Judging by the fact that no attempt was made to further distill the HTP for the final launch (between source and launch attempt it had decayed from 90% to 85%) I suspect that the HTP was sourced at 90%.  The comment "Note that 90% Peroxide will auto-decompose at 140 degrees Fahrenheit; this procedure is not recommended to those not fully familiar with Peroxide" implies that the author may work with HTP and sourced it from/alongside his commercial or academic employer.

This certainly shows that at least some people have used homemade HTP and lived (note survivor bias).  Presumably this would be more than enough to run a test HTP+napalm hybrid static fire.

How do you source the catalyst?  My first instinct would be a catalytic converter, preferably from a junk yard (and obviously those things are removed before crushing), but I have to wonder if you can separate the right catalyst from unneeded ones.  If you know the industrial name, you can probably obtain a "real" (chemical production) used catalyst for pennies on the dollar on ebay if you have sufficient patience (of course, you still have to outbid the raw material cost going to a recycler).

[sevenperforce]

1 hour ago, wumpus said:

I can't take jetpacks seriously (and there is hardly room for significant fuel.  It could very well use homemade HTP).
Copenhagen Suborbitals used homemade HTP (small amounts, because this appears to be a test that wasn't followed up on.  Current engines BPM2 and BPM5 appear to use LOX and alcohol.)
Small monoprop engine used homemade HTP.
Larger monoprop engine doesn't appear to list a source, and used a few gallons in test and presumably a bit more in the launch attempt.  Judging by the fact that no attempt was made to further distill the HTP for the final launch (between source and launch attempt it had decayed from 90% to 85%) I suspect that the HTP was sourced at 90%.  The comment "Note that 90% Peroxide will auto-decompose at 140 degrees Fahrenheit; this procedure is not recommended to those not fully familiar with Peroxide" implies that the author may work with HTP and sourced it from/alongside his commercial or academic employer.

I can't take jetpacks seriously either, but it was 90%+ HTP. Anything over 85% HTP would be enough for a static fire.

Speaking of which, why on earth has no one made an air-turboramrocket monopropellant jetpack? Waaaay more thrust and way more efficient.

1 hour ago, wumpus said:

How do you source the catalyst?  My first instinct would be a catalytic converter, preferably from a junk yard (and obviously those things are removed before crushing), but I have to wonder if you can separate the right catalyst from unneeded ones.  If you know the industrial name, you can probably obtain a "real" (chemical production) used catalyst for pennies on the dollar on ebay if you have sufficient patience (of course, you still have to outbid the raw material cost going to a recycler).

Unless you're using the highest grades of HTP, ordinary silver will do the trick. Not hard to get.

[wumpus]

24 minutes ago, sevenperforce said:

Speaking of which, why on earth has no one made an air-turboramrocket monopropellant jetpack? Waaaay more thrust and way more efficient.

Do *you* want to jump off a cliff and hope your jetpack starts?  Most jetpacks are low speed barely >1g.  The "ram" bit is going to require pretty close to supersonic (pulse jets might work better, but still require a lot of speed and probably painful jerks).  I don't think the "build a jet engine out of a car turbo's turbine" on youtube get remotely close to a TWR>1, not even including pilot.

[sevenperforce]

21 minutes ago, wumpus said:

Do *you* want to jump off a cliff and hope your jetpack starts?  Most jetpacks are low speed barely >1g.  The "ram" bit is going to require pretty close to supersonic (pulse jets might work better, but still require a lot of speed and probably painful jerks).  I don't think the "build a jet engine out of a car turbo's turbine" on youtube get remotely close to a TWR>1, not even including pilot.

Ooh, right. Correction: air-turborocket.

If you ran monopropellant through the edge/tip of a ducted turbine, the monopropellant would both spin the turbine and produce thrust, with the spinning turbine pulling through air to augment the thrust. You don't need any heavy motor to drive the turbine.

And no, I wouldn't jump off a cliff; I'd want to jump off the ground.

[TheEpicSquared]

Here's an idea to solve the issue of HTP being shot directly out of the nozzle, without coming into contact with the napalm first:

(sorry that it's sideways)

So the main thing here is the HTP deflector. As it's name suggests, it would deflect the HTP onto the napalm, so there would be little to no HTP leaving the nozzle without coming into contact with the napalm first. Theoretically, of course. The deflector would be attached to the fuselage by a series of struts, and would be made by a light material that is resistant against HTP. Conceivably, it could be made out of the same material as the HTP tank. 

 

EDIT: Also, if we decide to go with/talk about an HTP+kerosene liquid propellant rocket, I highly recommend we base it on the Gamma engines, for obvious reasons.

Edited July 28, 2017 by TheEpicSquared

[sevenperforce]

2 hours ago, TheEpicSquared said:

If we decide to go with/talk about an HTP+kerosene liquid propellant rocket, I highly recommend we base it on the Gamma engines, for obvious reasons.

Noooooooo. Gamma engines are pump-fed. Just because they are monoprop pump-fed doesn't make them simple. Pressure-fed all the way for us.

[TheEpicSquared]

11 hours ago, sevenperforce said:

Noooooooo. Gamma engines are pump-fed. Just because they are monoprop pump-fed doesn't make them simple. Pressure-fed all the way for us.

Oh right, yeah. I meant a pressure-fed version, but loosely based on the Gamma engine since it uses the same propellant. 

[DerekL1963]

On 7/21/2017 at 3:51 PM, sevenperforce said:

Errr...that was the geometry. It's a slow-flowing hybrid rocket, not a gel-liquid rocket.

Err...  That completely fails to address the issue I raised, which isn't viscosity - that having your propellant tank completely open to the combustion chamber is monumentally stupid.  You have tunneling problems from both ends, and tunnelling from the combustion chamber equates to rapid planned disassembly.

And I'm having a problem visualizing any fuel mix that won't simply flow out the nozzle while the vehicle is being fueled yet will still flow past the restrictor you're trusting to prevent combustion from propagating into the fuel mass.  That's a pretty steep order.
 

On 7/25/2017 at 7:08 AM, wumpus said:

How do you source the catalyst?  My first instinct would be a catalytic converter, preferably from a junk yard

From the reports I've heard, those don't work too well.  They aren't designed for liquid flow, let alone at the rates a rocket requires - as the catalyst is in the surface layer it's stripped (eroded) away within a few seconds to a minute at best.  Designing a functional cat pack, one that is structurally sound, allows sufficient flow, has sufficient performance, and which doesn't quickly strip is a *huge* challenge.  And that's for a conventional cat pack - this system as the orders-of-magnitude-more-difficult issue of having to be compact enough to fit within a combustion chamber and will have a challengingly small 'depth' (as seen by the HTP flow).

Between the challenges (and steep cost per flight) of a cat pack, the difficulty of obtaining HTP, and operating issues (such as needing to preheat the cat pack), pretty much nobody I've seen sticks with HTP long if they're serious about amatuer rocketry.  It's just too difficult to work with and offers few significant advantages over NOX or LOX to offset it's disadvantages.

And that's in conventional engines, this engine is...  unconventional and has numerous significant (and likely difficult and expensive to solve, if they can be solved) challenges of it's own.

[shynung]

18 minutes ago, DerekL1963 said:

From the reports I've heard, those don't work too well.  They aren't designed for liquid flow, let alone at the rates a rocket requires - as the catalyst is in the surface layer it's stripped (eroded) away within a few seconds to a minute at best.  Designing a functional cat pack, one that is structurally sound, allows sufficient flow, has sufficient performance, and which doesn't quickly strip is a *huge* challenge.  And that's for a conventional cat pack - this system as the orders-of-magnitude-more-difficult issue of having to be compact enough to fit within a combustion chamber and will have a challengingly small 'depth' (as seen by the HTP flow).

Going off on a slight tangent here. What if the cat pack only decomposed a limited amount of HTP, enough to maybe light up an ignition system or drive a turbopump? The rest of the HTP goes in as is, the decomposed HTP from earlier (along with some fuel) acting as a starting slug for the rocket.

[magnemoe]

On 25.7.2017 at 4:08 PM, wumpus said:

I can't take jetpacks seriously (and there is hardly room for significant fuel.  It could very well use homemade HTP).
Copenhagen Suborbitals used homemade HTP (small amounts, because this appears to be a test that wasn't followed up on.  Current engines BPM2 and BPM5 appear to use LOX and alcohol.)
Small monoprop engine used homemade HTP.
Larger monoprop engine doesn't appear to list a source, and used a few gallons in test and presumably a bit more in the launch attempt.  Judging by the fact that no attempt was made to further distill the HTP for the final launch (between source and launch attempt it had decayed from 90% to 85%) I suspect that the HTP was sourced at 90%.  The comment "Note that 90% Peroxide will auto-decompose at 140 degrees Fahrenheit; this procedure is not recommended to those not fully familiar with Peroxide" implies that the author may work with HTP and sourced it from/alongside his commercial or academic employer.

This certainly shows that at least some people have used homemade HTP and lived (note survivor bias).  Presumably this would be more than enough to run a test HTP+napalm hybrid static fire.

How do you source the catalyst?  My first instinct would be a catalytic converter, preferably from a junk yard (and obviously those things are removed before crushing), but I have to wonder if you can separate the right catalyst from unneeded ones.  If you know the industrial name, you can probably obtain a "real" (chemical production) used catalyst for pennies on the dollar on ebay if you have sufficient patience (of course, you still have to outbid the raw material cost going to a recycler).

Copenhagen Suborbitals plan to use LOX as oxidizer but use HTP monopropelant for the turbo pump, benefit is that it in practice will be an steam turbine, V2 and soyuz does this too. V2 Also used alcohol for fuel. 
 

[wumpus]

6 hours ago, DerekL1963 said:

From the reports I've heard, those don't work too well.  They aren't designed for liquid flow, let alone at the rates a rocket requires - as the catalyst is in the surface layer it's stripped (eroded) away within a few seconds to a minute at best.  Designing a functional cat pack, one that is structurally sound, allows sufficient flow, has sufficient performance, and which doesn't quickly strip is a *huge* challenge.  And that's for a conventional cat pack - this system as the orders-of-magnitude-more-difficult issue of having to be compact enough to fit within a combustion chamber and will have a challengingly small 'depth' (as seen by the HTP flow).

The cat pack would presumably be *before* the combustion chamber (unless all your catalysts can survive combustion temperature.  Silver certainly won't).  It needs to somehow maintain pressurization going in>going out>combustion chamber.  Which is certainly interesting as each subsequent stage is designed to increase pressure (presumably Bernoulli's principle is critical).

[Steel]

8 minutes ago, wumpus said:

The cat pack would presumably be *before* the combustion chamber (unless all your catalysts can survive combustion temperature.  Silver certainly won't).  It needs to somehow maintain pressurization going in>going out>combustion chamber.  Which is certainly interesting as each subsequent stage is designed to increase pressure (presumably Bernoulli's principle is critical).

 

Unlikely, I would say.  A flow like this is a multi-phase, chemically reacting flow through a complex geometry and I'd imagine there are some compressibility and thermal effects going on too, as well as significant turbulence. Bernoulli's principle works very well for low-speed, laminar flows through the centres of very wide pipes, but unlikely to be of use here. Cat packs and things of their nature (i.e thing trying to promote mixing and chemical reactions) are alway challenging design-wise.