I've had at least 50 people tell me the following:
(Including more than one scientist with a hard science PHD)
Why not put your rocket engine on top so the vehicle will be naturally stable.
This is wrong. It jives with our natural experience of the world, but it is wrong.
A rocket has no natural preference for thrusting UP. The rocket will thrust in whatever direction you point it. This is unusual in out natural experience. It you hang something on a rope the rope has the natural tendency to dangle straight down and only apply force in the up direction. If you attach something to a balloon the balloon only pulls straight up.
So given that the rocket will thrust in whatever direction its pointed and has no natural tendency to point up the rocket can't add any stability.
So if the motor can't add stability is there anything you can do for gravity to add stability? If the gravity field was uniform it would operate on the center of mass appling no torque to the vehicle and thus no stability. On the surface of the earth this is basically the case. The gravity field varies with the square of the radius. In orbit this slight difference can be used to stabilize a spacecraft, but on the surface the effect is so slight as to be undetectable. (On a 2meter high object gravity is 0.999999969 as strong on the top as it is on the bottom)
Our intuition is not completely wrong with respect to where the rocket motor goes, if it's center of thrust is not pointing through the center of mass then the rocket engine will apply a torque and the vehicle will spin. The current unreasonable rocket design has four engines that must be balanced to keep the vehicle from spinning, so in this sense a single rocket motor pointing toward the center of mass would keep the rocket pointed in a constant direction, but that direction would not be preferentially up without some kind of external control.
Wednesday, November 07, 2007
Monday, November 05, 2007
The Agony of the valves.
After spending a few days at XPC it's very clear that our system is too complex.
KISS Keep It Simple Stupid.
The temptation is very great to start over from scratch and redesign everything. If I were to start again I would design something that looks a lot like pixel or the Armadillo Quad, a Single engine. The counter to this is that the only thing we really need to finish our vehicle is fast robust reliable valves. Its always tempting to trade the devil you know for the invisible devil lying in the green grass on the other side of the fence. Everyone I've talked to in Alt space has had valve problems of one kind or another.
My core problem is that I need very fast (50 to 100msec) control of the engine thrust to maintain reliable attitude control. Our vehicle is relatively small so that it's overall rotational inertia is low, and the motors are on the very outside of the vehicle this combines to require fast/precise control of the motor thrust.
How fast?
We can do some freshman physics and figure that out.
Lets assume that the vehicle is 2m diameter sphere.
(This is a slightly pessimistic view of our inertia the vehicle will be more stable than this)
I=2 mr^2/5 =2m/5
We are hovering with 4 motors. The total required lift is mg
So the force for each motor is mg/4
The motors are thrusting on a 1 meter lever arm from the Cg.
Now assume we can very the thrust in 1% steps around nominal.
Assume we increase the thrust in one motor by 1% and decrease the opposite motor by 1%
torque=1 * 2%mg/4
angular acceleration alpha=torque /I =(1*0.02mg/4)/(2m/5)
alpha = 0.0125g (notice m drops out)
or assuming g=9.8m/sec
alpha = .1225 radians/sec ^2
If we want 1 degree control of the vehicle 1 degree = 0.01745 radians.
The rotation is just like linear acceleration angle = (alpha*t^2)/2
So for 1% motor change a 1 degree error occurs in t=.53 seconds.
We would like our control to be about 5x to 10x the speed hence we need a 50msec valve.
How do we get such fast control:
Monster actuators and normal ball valves.
Pros:
95% Off the shelf.
Cons:
Lots of hysteresis (3 to 5%), Seals wear out quickly.
Hysteresis really complicates the control system.
Voice coil driven piloted spool valves.
Pros:
Such things exist for Hydraulic systems.
Control response as fast as 15msec 0 to 100%
Hysteresis 0.1% Basically a perfect valve.
Cons:
No off the shelf valves will work for LOX
Heavy
Expensive.
Serious engineering effort to build such a valve in a Lox compatible way.
More complicated Odd combinations.
One can start doing things that add significant complexity:
Adding modulated water injection.
Modulating just the fuel supply while leaving the LOX on a slow actuator.
Using a pile of fast solenoid valves
One fast Solenoid valve as trim with Slow ball valve following.
Pros:
Potentially the lowest cost option.
Cons:
Violates KISS
Requires a lot of development testing.
I'm sure I'll post more on this in the coming days and weeks.
KISS Keep It Simple Stupid.
The temptation is very great to start over from scratch and redesign everything. If I were to start again I would design something that looks a lot like pixel or the Armadillo Quad, a Single engine. The counter to this is that the only thing we really need to finish our vehicle is fast robust reliable valves. Its always tempting to trade the devil you know for the invisible devil lying in the green grass on the other side of the fence. Everyone I've talked to in Alt space has had valve problems of one kind or another.
My core problem is that I need very fast (50 to 100msec) control of the engine thrust to maintain reliable attitude control. Our vehicle is relatively small so that it's overall rotational inertia is low, and the motors are on the very outside of the vehicle this combines to require fast/precise control of the motor thrust.
How fast?
We can do some freshman physics and figure that out.
Lets assume that the vehicle is 2m diameter sphere.
(This is a slightly pessimistic view of our inertia the vehicle will be more stable than this)
I=2 mr^2/5 =2m/5
We are hovering with 4 motors. The total required lift is mg
So the force for each motor is mg/4
The motors are thrusting on a 1 meter lever arm from the Cg.
Now assume we can very the thrust in 1% steps around nominal.
Assume we increase the thrust in one motor by 1% and decrease the opposite motor by 1%
torque=1 * 2%mg/4
angular acceleration alpha=torque /I =(1*0.02mg/4)/(2m/5)
alpha = 0.0125g (notice m drops out)
or assuming g=9.8m/sec
alpha = .1225 radians/sec ^2
If we want 1 degree control of the vehicle 1 degree = 0.01745 radians.
The rotation is just like linear acceleration angle = (alpha*t^2)/2
So for 1% motor change a 1 degree error occurs in t=.53 seconds.
We would like our control to be about 5x to 10x the speed hence we need a 50msec valve.
How do we get such fast control:
Monster actuators and normal ball valves.
Pros:
95% Off the shelf.
Cons:
Lots of hysteresis (3 to 5%), Seals wear out quickly.
Hysteresis really complicates the control system.
Voice coil driven piloted spool valves.
Pros:
Such things exist for Hydraulic systems.
Control response as fast as 15msec 0 to 100%
Hysteresis 0.1% Basically a perfect valve.
Cons:
No off the shelf valves will work for LOX
Heavy
Expensive.
Serious engineering effort to build such a valve in a Lox compatible way.
More complicated Odd combinations.
One can start doing things that add significant complexity:
Adding modulated water injection.
Modulating just the fuel supply while leaving the LOX on a slow actuator.
Using a pile of fast solenoid valves
One fast Solenoid valve as trim with Slow ball valve following.
Pros:
Potentially the lowest cost option.
Cons:
Violates KISS
Requires a lot of development testing.
I'm sure I'll post more on this in the coming days and weeks.
Wednesday, October 31, 2007
Unreasonable Plans
I enjoyed visiting with all the people that stopped by to visit at the Xprize cup.
It was really heartbreaking that Armadillo did not win anything. Watching this unfold shows how hard this problem really is and makes me realize how very far from being ready we really are. I've been trying to work up a plan of action for the next year and the rough outline looks something like this:
1)Start working on the command and control code on the Helicopter to get the telemetry and mission planning stuff out of the way. This can be done close to home without the major expedition aspects of going out to FAR. Id like to have this 100% resolved by Christmas.
2)Work on resolving my valve issues, this will probably be one of the following:
3)Resurrect the test stand even if it means making new tanks and resolving our engine igntion issues once and for all. Before we do any vehicle work I want to run a motor on the test stand with throttling and simulate a full LLC mission including the 30 minute turnaround. I want to do this over and over until we get it right. This may get as involved as developing a new injector and igniter design. I'd like to start this testing in January.
4)Once 1,2,3 are done rebuild the vehicle and start tethered testing. If all goes well I could see tethered testing as soon as Febuary 1 ~ 4 months from now. After watching Armadillo I know I want to make some architectural changes. The primary one will be for the vehicle to automatically test all its valve actuators and sensors with minimal human intervention.
When I get to the point of testing a full vehicle I need to find a different transportation method. I'd be inclinded to buy a used flatbed or Box truck, but I can't park that near me, so I'd need to find someplace in San Diego to park it without spending a fortune. Anyone with an empty lot in San Diego where I can park a 20' box truck off and on for a year?
It was really heartbreaking that Armadillo did not win anything. Watching this unfold shows how hard this problem really is and makes me realize how very far from being ready we really are. I've been trying to work up a plan of action for the next year and the rough outline looks something like this:
1)Start working on the command and control code on the Helicopter to get the telemetry and mission planning stuff out of the way. This can be done close to home without the major expedition aspects of going out to FAR. Id like to have this 100% resolved by Christmas.
2)Work on resolving my valve issues, this will probably be one of the following:
- Rework the tonegowa driven valves for less backlash and better electronics. (Open servo based?) This is my preference.
- Use higher pressure Butterfly valves as the sole valve. This is my sons preference.
- Design a custom valve using either rotary or poppet style valves. This is no-ones preference. (I'm thinking a bearing supported plug valve sort of like this)
3)Resurrect the test stand even if it means making new tanks and resolving our engine igntion issues once and for all. Before we do any vehicle work I want to run a motor on the test stand with throttling and simulate a full LLC mission including the 30 minute turnaround. I want to do this over and over until we get it right. This may get as involved as developing a new injector and igniter design. I'd like to start this testing in January.
4)Once 1,2,3 are done rebuild the vehicle and start tethered testing. If all goes well I could see tethered testing as soon as Febuary 1 ~ 4 months from now. After watching Armadillo I know I want to make some architectural changes. The primary one will be for the vehicle to automatically test all its valve actuators and sensors with minimal human intervention.
When I get to the point of testing a full vehicle I need to find a different transportation method. I'd be inclinded to buy a used flatbed or Box truck, but I can't park that near me, so I'd need to find someplace in San Diego to park it without spending a fortune. Anyone with an empty lot in San Diego where I can park a 20' box truck off and on for a year?
Tuesday, October 23, 2007
Good Luck to Armadillo
I will be leaving for Holloman some time Wednesday afternoon.
Before I go I want to wish armadillo the best of luck in their NG-LLC efforts.
I will be rooting for them!
They have worked very hard and have been a real class act.
Good luck to John and the rest of the Armadillo team!
Before I go I want to wish armadillo the best of luck in their NG-LLC efforts.
I will be rooting for them!
They have worked very hard and have been a real class act.
Good luck to John and the rest of the Armadillo team!
Long night we are ok...
The wind switched directions and it looks like the witch fire will not reach the coast. Our thoughts are with the 500,000 people that have been evacuated and don't know the status of their homes. It looks like 1200+ homes have been destroyed in the last 36 hours. There are still areas in San Deigo county where people are still losing homes. If the wind switches we could still be at risk, but
it looks 200% better than is did 24 hours ago.
it looks 200% better than is did 24 hours ago.
Monday, October 22, 2007
San Diego fires
We live in Solana Beach, the city has just said
"Everyone is being asked to plan, pack and evacuate ahead of
being required to do so. "
It looks like the witch creek fire is likely going to burn all the way to the coast. Where it crosses I5 and hits the coast is pretty much up in the air. It looks like its going to cross somewhere near our house +/- 5 miles. We live in a fairly dense residential neighborhood, if it gets to us this fire is going to be a truely note worthy disaster. I'm going home from work to join the rest of the family and get prepared to leave. It probably won't be to the coast for another 12-18 hours , but it looks like nothing is going to stop it. Wish us luck, we hope to see all of you this coming weekend at Holloman. I'll let everyone know how it turns out Tuesday.
Paul
"Everyone is being asked to plan, pack and evacuate ahead of
being required to do so. "
It looks like the witch creek fire is likely going to burn all the way to the coast. Where it crosses I5 and hits the coast is pretty much up in the air. It looks like its going to cross somewhere near our house +/- 5 miles. We live in a fairly dense residential neighborhood, if it gets to us this fire is going to be a truely note worthy disaster. I'm going home from work to join the rest of the family and get prepared to leave. It probably won't be to the coast for another 12-18 hours , but it looks like nothing is going to stop it. Wish us luck, we hope to see all of you this coming weekend at Holloman. I'll let everyone know how it turns out Tuesday.
Paul
Friday, October 19, 2007
Unreasonable Ideas
For awhile I've been contemplating making some personal or political posts on this blog. I don't really want to mix the messages that way. Today I started a new blog unreasonableideas with a sad personal note. I'll continue posting rocket stuff here, and I'll post personal stuff there.
Wednesday, October 10, 2007
We will be displaying at XPC.
I've been having an internal debate about coming to the Xprize cup as an exhibitor or strictly as an observer. Unlike the other teams that are are looking to raise capital and awareness, we are not yet trying to do that. So I was hesitant to spend the money necessary to transport stuff to the show. I've decided that it would serve my larger goals of showing that small teams and individuals can do significant things in "space development" so we will be there.
We will be bringing the complete vehicle minus some valves and plumbing.
We may also bring the test stand carcass, the test helicopter, and and a video display. If you are coming to the show stop by and say hi.
On a personal note I went to the Plaster Blaster event last Saturday and spent the day watching a huge array of people launch rockets of all shapes and sizes. It was my first trip to a high power rocket event. The Xwing (http://rocketdungeon.blogspot.com/2007/10/empire-struck-back-may-x-wing-rip.html)was very cool, but all in all I found the event somewhat depressing. There were several cool projects, but none of the projects seemed to be advancing the state of the art. In some ways it seemed like a conspicuous consumption event. To be fair I saw a lot of families there and that was a very cool aspect to the event. My wife chastised me for this attitude, and said who am I to be judging other peoples efforts. She is probably right.
Lastly I've not done ANY thing on the rocket in the last month, I needed the break. I've been trying to catch up at work, organize my office and play some video games... (online chess and replaying all the original starcraft scenarios.)
We will be bringing the complete vehicle minus some valves and plumbing.
We may also bring the test stand carcass, the test helicopter, and and a video display. If you are coming to the show stop by and say hi.
On a personal note I went to the Plaster Blaster event last Saturday and spent the day watching a huge array of people launch rockets of all shapes and sizes. It was my first trip to a high power rocket event. The Xwing (http://rocketdungeon.blogspot.com/2007/10/empire-struck-back-may-x-wing-rip.html)was very cool, but all in all I found the event somewhat depressing. There were several cool projects, but none of the projects seemed to be advancing the state of the art. In some ways it seemed like a conspicuous consumption event. To be fair I saw a lot of families there and that was a very cool aspect to the event. My wife chastised me for this attitude, and said who am I to be judging other peoples efforts. She is probably right.
Lastly I've not done ANY thing on the rocket in the last month, I needed the break. I've been trying to catch up at work, organize my office and play some video games... (online chess and replaying all the original starcraft scenarios.)
Wednesday, September 19, 2007
400 Days till XPC 2008
I will boldly predict that there will be NG-LLC prize money for 2008. We only have ~400 days until the 2008 XPC, 280 days till the FAA permit app must be accepted. What are our plans? In no particular order...
1)Simplify.
Make one valve work, not two,
Go to blow down pressurization (for at least the 90 sec vehicle.)
2)Add more diagnostic automation.
Add some more feedback to the open loop vales so we can automagically determine their health.We need both position and current feedback from each valve. I may convert the valves to www.openservo.org derived control electronics.
3)Build a more robust vehicle.
Most plumbing, stainless not aluminum.
sturdier landing gear.
4)Find a more benign transport system.
5)Try other fuels and gasses
IPA (cleaner) and E85 cheaper.
Do at least one burn with 100% Nitrogen pressurization.
With our long thin tanks it might not be as bad as it is for Carmacks Spherical tanks. I've been told that a shot of He followed by N2 pressurization is not bad. the Russians use Nitrogen to pressurize their Lox tanks, and Nitrogen is a Lot Lot Lot cheaper than Hydrogen.
(Self presurized Lox might be similar....)
7)Put better data logging software in place.
( I write embedded S/W for a living and the shoemakers kids have no shoes.)
8)Convert the simulator to a hardware in loop tester.
9)Make the control system fly the helicopter, and publish ALL the results.
10)Try a impinging injector rather than a pintile.
11)Try Charles Pooleys Lox pre-burner idea.
12)Build and leave set up a good valve and injector flow test setup.
1)Simplify.
Make one valve work, not two,
Go to blow down pressurization (for at least the 90 sec vehicle.)
2)Add more diagnostic automation.
Add some more feedback to the open loop vales so we can automagically determine their health.We need both position and current feedback from each valve. I may convert the valves to www.openservo.org derived control electronics.
3)Build a more robust vehicle.
Most plumbing, stainless not aluminum.
sturdier landing gear.
4)Find a more benign transport system.
5)Try other fuels and gasses
IPA (cleaner) and E85 cheaper.
Do at least one burn with 100% Nitrogen pressurization.
With our long thin tanks it might not be as bad as it is for Carmacks Spherical tanks. I've been told that a shot of He followed by N2 pressurization is not bad. the Russians use Nitrogen to pressurize their Lox tanks, and Nitrogen is a Lot Lot Lot cheaper than Hydrogen.
(Self presurized Lox might be similar....)
7)Put better data logging software in place.
( I write embedded S/W for a living and the shoemakers kids have no shoes.)
8)Convert the simulator to a hardware in loop tester.
9)Make the control system fly the helicopter, and publish ALL the results.
10)Try a impinging injector rather than a pintile.
11)Try Charles Pooleys Lox pre-burner idea.
12)Build and leave set up a good valve and injector flow test setup.
Monday, September 17, 2007
Quick Update on LLC 2007
Since I posted my Out of Time post, a couple of teams have
announced to the world what they had told me in private.
Acuity:
Very Secret I know almost nothign about their progress. They had an unflown vehicle at the 2006 XPC, they could be the dark horse. They have an interesting control scheme that always made me wonder.
Armadillo:
As ready as anyone could be, the "Gold Standard"
Bon Nova:
They have posted a couple of very quick Rocket Motor videos, the longest being several seconds. We posted our 106 Second firing in April and we did not make it. They have posted no vehicle hardware pictures.
Masten:
They just announced on their blog they are out for 2007.
Micro space:
Failed to attend the required team meeting in Aug.
Paragon Labs:
They have a very credible vehicle, well constructed and professional Another team that is somewhat secretive and an unknown. They posted finished airframe and rocket firing pictures in Aug. They were planning to have throttling via movable pintile in the all aluminum motor, while technically very cool, not easy to do and Armadillo was never able to make an all aluminum motor last without melting.
Speed Up:
Announced that they will not make 2007.
Unreasonable Rocket:
Announced we will not make it in 2007.
Team X :
Pulled out before the Last team summit.
announced to the world what they had told me in private.
Acuity:
Very Secret I know almost nothign about their progress. They had an unflown vehicle at the 2006 XPC, they could be the dark horse. They have an interesting control scheme that always made me wonder.
Armadillo:
As ready as anyone could be, the "Gold Standard"
Bon Nova:
They have posted a couple of very quick Rocket Motor videos, the longest being several seconds. We posted our 106 Second firing in April and we did not make it. They have posted no vehicle hardware pictures.
Masten:
They just announced on their blog they are out for 2007.
Micro space:
Failed to attend the required team meeting in Aug.
Paragon Labs:
They have a very credible vehicle, well constructed and professional Another team that is somewhat secretive and an unknown. They posted finished airframe and rocket firing pictures in Aug. They were planning to have throttling via movable pintile in the all aluminum motor, while technically very cool, not easy to do and Armadillo was never able to make an all aluminum motor last without melting.
Speed Up:
Announced that they will not make 2007.
Unreasonable Rocket:
Announced we will not make it in 2007.
Team X :
Pulled out before the Last team summit.
Sunday, September 16, 2007
Out of Time
The end of 2007
We took the complete vehicle out to FAR to do a four engine static test this weekend. We had a number of transport issues. We finally settled on a U haul trailer.
With the motors mounted the vehicle did not fit. So we unmounted the four motors. This left a fair bit dangling plumbing. Realize that this is a trailer with leaf springs and no shocks. The trailer is rated for 4500LBs we put 230 lbs in it. WE then drove for three hours to Mojave. We stopped early in the trip to check the tie downs and again at Mojave. By the time we reached the Arco station in Mojave we had either damaged the plumbing or shaken the hardware off of the valves for 19 of the 21 valves. The trip killed the vehicle. This ends the 2007 effort.
This is a lesson in construction. WE need to pay more attention to transport with a "Real" suspension and we need a lot more plumbing support brackets etc...
Also what are we doing with 21 Valves?
On Each Quadrant: (4 each for 16)
Main Lox
Main Fuel
Lox Throttle
Fuel Throttle
On the Top (5)
Lox Safety pop off
Fuel Safety Pop off
Master Pressurization
Master Fuel Purge.
Igniter Dual Valve.
This is part of our problem. We could not get the ball valves to throttle/operate fast enough for our throttle and we could not get the fast butterflies to seal so we doubled the quadrant valves. If we had more time we would had fixed the big ball valves with shims and shaped orifices, removing one whole set of valves. We applied a quick fix and it failed.
Going forward/Don Quixote
We have 34 days till the practice session at the NG-LLC site. We have 41 days till the contest. I made a spread sheet with a list of the tasks necessary to compete. I made an optimistic and pessimistic time estimate. If I stopped going to work (I've been working 4 days a week) and worked full time for the next 41 days, the optimistic schedule says I have 7 Extra days before the practice session. The Pessimistic schedule says I'd be 4 days late for the contest.
My Day Job is CTO of Netburner, I'm one of the founders and the success of that company is the source of funding that makes Unreasonable Rocket possible. In the last year I've been putting most of my creative efforts toward this project and my business has suffered as a result. How much more do I commit? These are agonizing decisions. The Logical decision would be to suspend the effort for this year and restart if there is any prize money left after the contest.
Evaluating other teams for 2007/2008
I've been trying to keep track of the other teams and Judge the status of their efforts. There are 9 teams. Armadillo is as ready as anyone is ever going to get. Unreasonable Rocket is not going to make it in 2007. Two teams dropped out by not making the summit. That leaves five teams. Two teams have privately told me they won't make it. One team has asked if they can share test days with me at FAR,I Said yes, no problem. (If they are just starting serious rocket engine tests they won't make it) One more team privately told me they were giving up on the 180 second contest for this year. This leaves one team unknown for the 180 second flight. Only Armadillo has anything posted on the FAA website. I have to conclude that it will probably be the Armadillo show this year at XPC.
Even Armadillo has some issues, they crashed texel and have a supplier problem with their graphite chambers for long duration high pressure operation. (180 seconds). If I were a betting man I'd give 90% odds that there will still be 2nd place 500K available next year.
This has been the most difficult post to write, I know a lot of people have been following and rooting for the father and son team and I'm sorry to let you all down. Be assured that we will continue. We will probably take a month off to rest. Tonight I'm going to do something I have not done in a year. I'm going to sit a and watch the Chargers Patriots game. . I spent 10 years living near Boston, GO Pats, I've spent 15 years in the San Diego area, GO Bolts. So I don't know who to root for, but it should be a good game.
We took the complete vehicle out to FAR to do a four engine static test this weekend. We had a number of transport issues. We finally settled on a U haul trailer.
With the motors mounted the vehicle did not fit. So we unmounted the four motors. This left a fair bit dangling plumbing. Realize that this is a trailer with leaf springs and no shocks. The trailer is rated for 4500LBs we put 230 lbs in it. WE then drove for three hours to Mojave. We stopped early in the trip to check the tie downs and again at Mojave. By the time we reached the Arco station in Mojave we had either damaged the plumbing or shaken the hardware off of the valves for 19 of the 21 valves. The trip killed the vehicle. This ends the 2007 effort.
This is a lesson in construction. WE need to pay more attention to transport with a "Real" suspension and we need a lot more plumbing support brackets etc...
Also what are we doing with 21 Valves?
On Each Quadrant: (4 each for 16)
Main Lox
Main Fuel
Lox Throttle
Fuel Throttle
On the Top (5)
Lox Safety pop off
Fuel Safety Pop off
Master Pressurization
Master Fuel Purge.
Igniter Dual Valve.
This is part of our problem. We could not get the ball valves to throttle/operate fast enough for our throttle and we could not get the fast butterflies to seal so we doubled the quadrant valves. If we had more time we would had fixed the big ball valves with shims and shaped orifices, removing one whole set of valves. We applied a quick fix and it failed.
Going forward/Don Quixote
We have 34 days till the practice session at the NG-LLC site. We have 41 days till the contest. I made a spread sheet with a list of the tasks necessary to compete. I made an optimistic and pessimistic time estimate. If I stopped going to work (I've been working 4 days a week) and worked full time for the next 41 days, the optimistic schedule says I have 7 Extra days before the practice session. The Pessimistic schedule says I'd be 4 days late for the contest.
My Day Job is CTO of Netburner, I'm one of the founders and the success of that company is the source of funding that makes Unreasonable Rocket possible. In the last year I've been putting most of my creative efforts toward this project and my business has suffered as a result. How much more do I commit? These are agonizing decisions. The Logical decision would be to suspend the effort for this year and restart if there is any prize money left after the contest.
Evaluating other teams for 2007/2008
I've been trying to keep track of the other teams and Judge the status of their efforts. There are 9 teams. Armadillo is as ready as anyone is ever going to get. Unreasonable Rocket is not going to make it in 2007. Two teams dropped out by not making the summit. That leaves five teams. Two teams have privately told me they won't make it. One team has asked if they can share test days with me at FAR,I Said yes, no problem. (If they are just starting serious rocket engine tests they won't make it) One more team privately told me they were giving up on the 180 second contest for this year. This leaves one team unknown for the 180 second flight. Only Armadillo has anything posted on the FAA website. I have to conclude that it will probably be the Armadillo show this year at XPC.
Even Armadillo has some issues, they crashed texel and have a supplier problem with their graphite chambers for long duration high pressure operation. (180 seconds). If I were a betting man I'd give 90% odds that there will still be 2nd place 500K available next year.
This has been the most difficult post to write, I know a lot of people have been following and rooting for the father and son team and I'm sorry to let you all down. Be assured that we will continue. We will probably take a month off to rest. Tonight I'm going to do something I have not done in a year. I'm going to sit a and watch the Chargers Patriots game. . I spent 10 years living near Boston, GO Pats, I've spent 15 years in the San Diego area, GO Bolts. So I don't know who to root for, but it should be a good game.
Thursday, September 13, 2007
The New X prize.
I'm really disappointed in the new Google Lunar Xprize.
It would be a great prize 10 years from now, but today it just illustrates the core problem with space access. The high cost of access to low earth orbit.
The grand prize is 20M only twice what the original x-prize, yet the problem is at least 100 times as hard. I can't imagine what group or company would go after this prize.
Even if it is won, I fear it will not add much to reducing the cost of access.
It might be done as a stunt with a 500 gm Microrover.
I fear it will be a cool footnote, and will be a lot like Bigelows Americas space prize, The ratio of difficulty to winnings is just too high. (I personally think that Bigelows prize is of similar difficulty to the Google Lunar Xprize, and is twice the $$)
There are a number of firms working on high performance sub orbital aiming toward orbital launchers , Armadillo, Garvey Space, Micro-launchers, Masten etc...
If the intent of prizes is to encourage space exploration, A prize to encourage transport development would be so much more useful. I'd like to see a prize for a reusable orbital launcher, just something to launch 350 gram can sats.
It would be a great prize 10 years from now, but today it just illustrates the core problem with space access. The high cost of access to low earth orbit.
The grand prize is 20M only twice what the original x-prize, yet the problem is at least 100 times as hard. I can't imagine what group or company would go after this prize.
Even if it is won, I fear it will not add much to reducing the cost of access.
It might be done as a stunt with a 500 gm Microrover.
I fear it will be a cool footnote, and will be a lot like Bigelows Americas space prize, The ratio of difficulty to winnings is just too high. (I personally think that Bigelows prize is of similar difficulty to the Google Lunar Xprize, and is twice the $$)
There are a number of firms working on high performance sub orbital aiming toward orbital launchers , Armadillo, Garvey Space, Micro-launchers, Masten etc...
If the intent of prizes is to encourage space exploration, A prize to encourage transport development would be so much more useful. I'd like to see a prize for a reusable orbital launcher, just something to launch 350 gram can sats.
Wednesday, September 12, 2007
Win some loose some...
Tonight I finished the last little bit of wiring on the vehicle.
All the cable bundles had been run a few days ago, I just had a few misc connectors to solder on or wiring errors to fix.
We then went about systematically checking out quadrants.
Some where in the middle of doing this I tripped on the Ethernet cable going to the LapTop and the resultant experiment in inelastic collisions took out the LapTop screen.
Fortunately there is no shortage of computers in the Breed household.
All the cable bundles had been run a few days ago, I just had a few misc connectors to solder on or wiring errors to fix.
We then went about systematically checking out quadrants.
Some where in the middle of doing this I tripped on the Ethernet cable going to the LapTop and the resultant experiment in inelastic collisions took out the LapTop screen.
Fortunately there is no shortage of computers in the Breed household.
Tuesday, September 11, 2007
Really good news...
The vehicle is 100% hardware complete.
We weighed it and we are at least 10% under our target weight!!!!!!!
I'm not going to publish the weight until I can repeat the measurement, with a better calibrated scale,but this gives us significant performance margin for reaching 180 seconds!
More details:
The target weight with payload was 326 lbs.
The target empty weight was 271 lbs
The actual empty weight 230 Lbs.
My actual empty weight is 15% under Budget!!!
In order to do the 180 seconds I need a realized in flight ISP of ~152
As John Carmack rightly points out it won't be as high as I expect or wish.
The theoretical ISP for the pressures and fuel combination I'm using is 227
So I need to realize 66% of theoretical.
This is with tanks 90% full.
If I go to tanks 97% full I need an ISP of 145
We weighed it and we are at least 10% under our target weight!!!!!!!
I'm not going to publish the weight until I can repeat the measurement, with a better calibrated scale,but this gives us significant performance margin for reaching 180 seconds!
More details:
The target weight with payload was 326 lbs.
The target empty weight was 271 lbs
The actual empty weight 230 Lbs.
My actual empty weight is 15% under Budget!!!
In order to do the 180 seconds I need a realized in flight ISP of ~152
As John Carmack rightly points out it won't be as high as I expect or wish.
The theoretical ISP for the pressures and fuel combination I'm using is 227
So I need to realize 66% of theoretical.
This is with tanks 90% full.
If I go to tanks 97% full I need an ISP of 145
Friday, September 07, 2007
I'll sleep when I'm dead.
So much to do, there's plenty on the farm
I'll sleep when I'm dead
Saturday night I like to raise a little harm
I'll sleep when I'm dead
I'm drinking heartbreak motor oil and Bombay gin
I'll sleep when I'm dead
Straight from the rocket , twisted again
I'll sleep when I'm dead
Paraphrased from Warren Zevon.
Today I machined the last part.
If it all works the rocket hardware is done.
We have been trying to test it for the last three weeks.
We thought we had a chance to test two weeks ago Saturday.
We thought we would test with one motor last Saturday, alas when we flow tested the motor we were going to use, it was unusable, and may be why our last test failed. So I spent the last week building and carefully QA-ing 5 motors. I've taken detailed pictures of the whole process and after the XPC I'll post the drawings and detailed machining documentation.
So here it is three weeks after I first thought we might test the full up vehicle in a static fire, I've worked 18 and 20 hour days for three weeks and we have a shot at being ready for Saturday. I keep telling people we are testing next staurday,and I'm feeling like a flake. There are always a million details. Example Today my son and I are going over the new igniter plumbing and I realized that we had not put in the necessary check valves. So we are redoing that section of plumbing. (My son is currently driving back from the LA McMaster Carr will call with the check valves.) I'll post more later.
I'll sleep when I'm dead
Saturday night I like to raise a little harm
I'll sleep when I'm dead
I'm drinking heartbreak motor oil and Bombay gin
I'll sleep when I'm dead
Straight from the rocket , twisted again
I'll sleep when I'm dead
Paraphrased from Warren Zevon.
Today I machined the last part.
If it all works the rocket hardware is done.
We have been trying to test it for the last three weeks.
We thought we had a chance to test two weeks ago Saturday.
We thought we would test with one motor last Saturday, alas when we flow tested the motor we were going to use, it was unusable, and may be why our last test failed. So I spent the last week building and carefully QA-ing 5 motors. I've taken detailed pictures of the whole process and after the XPC I'll post the drawings and detailed machining documentation.
So here it is three weeks after I first thought we might test the full up vehicle in a static fire, I've worked 18 and 20 hour days for three weeks and we have a shot at being ready for Saturday. I keep telling people we are testing next staurday,and I'm feeling like a flake. There are always a million details. Example Today my son and I are going over the new igniter plumbing and I realized that we had not put in the necessary check valves. So we are redoing that section of plumbing. (My son is currently driving back from the LA McMaster Carr will call with the check valves.) I'll post more later.
Monday, September 03, 2007
Do you have a rocket problem?
If your garage sink has sprouted strange blue plumbing...
If you spend hours in the hot sun with a magnifying glass and a stop watch
staring at streams of water..
If you can quote the National fire protection standards for cryogenic fluids to the code enforcement officer, without notes.
If you know exactly what chemicals are used to denature ethanol, and can quote the stock numbers for the different types from the local chemical supplier.
If you collect strange copper sculptures.
If you know the density of several kinds of alcohol in both English and metric units.
If you have a sleepless night worring about how to rotate an Inertia Tensor
(And your friends solve the problem by return E-mail)
If you have a weekly conference call to a federal agency to explain how you problem is going...
If one of your buddies stops by to visit on the weekend and the first question he asks "are there any stainless chips in the chips on the floor" He's barefoot and his feet are just fine with aluminum chips, but they are not yet tough enough for stainless.
If you are proud of your AN fittings collection.
If you know the hours of and directions to the McMaster Carr will call window.
If you this looks like you, you have arocket problem, seek help.
If you spend hours in the hot sun with a magnifying glass and a stop watch
staring at streams of water..
If you can quote the National fire protection standards for cryogenic fluids to the code enforcement officer, without notes.
If you know exactly what chemicals are used to denature ethanol, and can quote the stock numbers for the different types from the local chemical supplier.
If you collect strange copper sculptures.
If you know the density of several kinds of alcohol in both English and metric units.
If you have a sleepless night worring about how to rotate an Inertia Tensor
(And your friends solve the problem by return E-mail)
If you have a weekly conference call to a federal agency to explain how you problem is going...
If one of your buddies stops by to visit on the weekend and the first question he asks "are there any stainless chips in the chips on the floor" He's barefoot and his feet are just fine with aluminum chips, but they are not yet tough enough for stainless.
If you are proud of your AN fittings collection.
If you know the hours of and directions to the McMaster Carr will call window.
If you this looks like you, you have arocket problem, seek help.
Friday, August 24, 2007
Vehicle progress.
The vehicle is coming along nicely. We were planning to test this weekend and we could probably be ready with p=.8, but things would be rushed and unchecked. We will test next weekend and we will be really ready. Current progress:
Propane igniter:
We did some testing with using a normal camp stove propane cylinder as the fuel source for the igniter, and it looks like the tank orifice is too small and it won't feed 4 motors. We will be switching to a paint ball tank for the propane source tank.
Paperwork:
I've been working on the hardware and have neglected the FAA paperwork side. They are going to put my 120 day clock on hold until I finish up some details I owe them.
- The top side pressurization, regulator and blow off vent valves are all done.
- The igniter plumbing is all done.
- 3 of the four motors are plumbed.
- The structural framing is all complete.
- The first cut of the landing gear is done and 3 of 4 are on the vehicle.
- (Were going to change the Landing gear slightly so we don't melt it.)
- The new control board electronics have finished initial testing and seem to work.
Propane igniter:
We did some testing with using a normal camp stove propane cylinder as the fuel source for the igniter, and it looks like the tank orifice is too small and it won't feed 4 motors. We will be switching to a paint ball tank for the propane source tank.
Paperwork:
I've been working on the hardware and have neglected the FAA paperwork side. They are going to put my 120 day clock on hold until I finish up some details I owe them.
Saturday, August 18, 2007
Getting the vehicle ready.
While I probably don't mention them enough there are a number of people that are helping this project significantly.
For the past six months I've been working on this project three days a week, Friday, Saturday and Sunday all day, as well as evenings the rest of this week.
This week we are trying to get the whole vehicle ready for a single engine test firing next weekend. To have any chance of doing this I'm taking a week and half off of work and doing nothing but unreasonable Rocket.
Fridays Progress:
I worked on the ground equipment case that holds the data recorder, telemetry radios, video receivers etc.... (This is now Jasons project)
I fabricated and tested a small dual 1/8" ball valve actuator to replace our unreliable igniter solenoids.
I finished the servo mountings on the safety vent valves.
My Son Plumbed the pressurization system and with Carl's help at Flowmetrics got the regulator working.
My son continued to plumb the vehicle.
I put together another "hardware tour" video of the vent and igniter valves.
Today we are going to combine a trip to the Los Angles McMaster Carr will call with a trip to see my Father who is recovering from Knee replacement surgery in Long Beach..
- Charles Pooley has been an invaluable resource to discuss rocket ideas and to bounce ideas off of.
- The guys at flowmetrics have their shop about 1/2 mile from my house. They have been very helpful with knowledge, know how and ideas.
- My sons friend Jason. Jason is home from college for the summer and spends considerable time in our garage helping with the electronics, software and the much appreciated shop entropy control.
- Mark, Kevin and Ted at Friends of amateur rocketry.
- Bob Nortman has been doing all of our aluminum welding.
For the past six months I've been working on this project three days a week, Friday, Saturday and Sunday all day, as well as evenings the rest of this week.
This week we are trying to get the whole vehicle ready for a single engine test firing next weekend. To have any chance of doing this I'm taking a week and half off of work and doing nothing but unreasonable Rocket.
Fridays Progress:
I worked on the ground equipment case that holds the data recorder, telemetry radios, video receivers etc.... (This is now Jasons project)
I fabricated and tested a small dual 1/8" ball valve actuator to replace our unreliable igniter solenoids.
I finished the servo mountings on the safety vent valves.
My Son Plumbed the pressurization system and with Carl's help at Flowmetrics got the regulator working.
My son continued to plumb the vehicle.
I put together another "hardware tour" video of the vent and igniter valves.
Today we are going to combine a trip to the Los Angles McMaster Carr will call with a trip to see my Father who is recovering from Knee replacement surgery in Long Beach..
Monday, August 13, 2007
Disapointing weekend.
We spent a long 16 hour day out at the test site and never got the igniter to light. We had some kind of sludge form in the ethanol tanks and it kept clogging the igniter solenoid and filter. It was a very discouraging day.
We test again in two weeks. We have a long list of things to try.
1)Change to isopropyl alcohol for less residue.
2)change to propane for the igniter fuel.
3)Possibly change to a pyro igniter based on a small solid rocket motor.
(This is a major logistics hassle, but simplifies and lightens the vehicle.)
If we do not get reliable ignition and throttling working by the end of that weekend, we are realistically done for this year.
The one bright spot was that we were sharing the test facilities with Garvey space and they had a successful test. Seeing a 5K motor running is a beautiful thing. I have some awesome video, and I will post it as soon as I get permission from Garvey.
We test again in two weeks. We have a long list of things to try.
1)Change to isopropyl alcohol for less residue.
2)change to propane for the igniter fuel.
3)Possibly change to a pyro igniter based on a small solid rocket motor.
(This is a major logistics hassle, but simplifies and lightens the vehicle.)
If we do not get reliable ignition and throttling working by the end of that weekend, we are realistically done for this year.
The one bright spot was that we were sharing the test facilities with Garvey space and they had a successful test. Seeing a 5K motor running is a beautiful thing. I have some awesome video, and I will post it as soon as I get permission from Garvey.
Thursday, August 09, 2007
72 Days left...
There are 72 days until the contest.
Its going to be really busy!
I went to the team summit last week and it looks like we did not scare the Airforce too bad ;-).
The Local paper put us on the front page. (Web version)
I'm testing again this weekend, I realize that I've been lax in updating the blog, but hardware comes first. I just finished making my first set of safety relief valves, they hold to 1100 PSI
and open instantaneously, when I deliberately added a bit of air before pumping up the hydro tester it sounds like a gun shot when it opens. As I have to prepare pictures and test docs for these valves for the FAA I'll post them here as well.
Its going to be really busy!
I went to the team summit last week and it looks like we did not scare the Airforce too bad ;-).
The Local paper put us on the front page. (Web version)
I'm testing again this weekend, I realize that I've been lax in updating the blog, but hardware comes first. I just finished making my first set of safety relief valves, they hold to 1100 PSI
and open instantaneously, when I deliberately added a bit of air before pumping up the hydro tester it sounds like a gun shot when it opens. As I have to prepare pictures and test docs for these valves for the FAA I'll post them here as well.
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