Ask Derek Deville About High-Altitude Amateur Rocketry

A few days ago, we posted about Derek Deville's mind-blowing high-altitude rocket-launch in the Nevada desert. His 14-foot, GPS-equipped (four GPS units, actually) home-made rocket ("Qu8k") managed to hit 121,000 feet, an effort that took more than a trip to the store for more Estes "D" engines. Derek has graciously agreed to answer questions about Qu8k and other rocketry projects. Please confine your questions to one per post, but ask as many as you'd like.

Comments

ATF?

[dtmos]

How has the relationship with the ATF and other government agencies affected amateur rocketry since 9/11?

Public support?

[dtmos]

Back in the 1950s and 1960s in the US, model rocketry was promoted as a way to interest youth in science and technology and, therefore, strengthen and defend the nation. However, amateur and, to a lesser extent, model rocketry are today seen by much of the public as a dangerous technology that should be suppressed, to keep it out of the hands of dangerous terrorists. How can the rocketry community regain public support?

Oldest and newest flight technologies.

[deathcloset]

I ( and many others ) have been thinking about balloon assisted launch systems recently.

Balloons seem like an excellent and flexible launch element which could offer a ton of altitude and avoidance of at least some friction. Have you heard of or considered this?

Re:Oldest and newest flight technologies.

[wagnerrp]

The problem with balloon launches is the same problem with mothership launches like the SpaceShipOne. Once you get up to altitude, and modest speed, so what? The White Knight gets you to around 15km and 200m/s. Balloons get you to around 30km and 0m/s. Meanwhile, LEO starts around 150km and 8000m/s, which at that altitude is only good for a couple days before you re-enter. They can get you a decent chunk of the altitude, but are nowhere near the velocity requirements. Remember, fuel and launch mass varies exponentially with your velocity requirement. As for getting out of the thick low atmosphere, that's only going to save you a couple hundred meters per second at the most.

Now that space donut is something completely different. While motherships and balloons can't achieve the necessary velocity to be worthwhile, guns can. The problem with guns is that you need a very long barrel to get sufficiently low acceleration to be useful for more delicate payloads. You have to launch at a high inclination, so you either need an extremely deep mine shaft, or an extremely tall structure (or one built up the side of a tall mountain). The space donut is a way to build that tall structure. Rather than having it self-supporting, you use buoyancy to do it for you. Make it lighter than air, and use guy wires to position and stabilize it. You can build it as tall as the atmosphere will support it.

Towards Orbital Rocketry

[Anonymous Coward]

Are there plans or even a roadmap you could lay out towards orbital rocketry by serious amateur groups?

what are the laws about this

[Anonymous Coward]

What rules & laws do you have to follow launching a rocket like this? With so many aircraft in the air im sure there must be

Re:GPS

[kimvette]

Those limits are voluntary and vary from manufacturer to manufacturer, and many devices ignore those artificial limitations. Even if the restrictions are honored by a given device, the firmware can often be modified to remove those restrictions, and it is still perfectly legal for domestic use; it just can't be exported without an export permit since it is then regarded as munitions (much like high-grade encryption back in the day). Lastly, the export restriction applies only to devices to devices when speed AND altitude limitations are exceeded, since the export restrictions are intended to prevent use on an ICBM.

http://en.wikipedia.org/wiki/Global_Positioning_System#Restrictions_on_civilian_use

http://www.groupsrv.com/science/about460860.html

Attitude Control

[charlesherdt]

How did you maintain attitude on the rocket? I don't see any control mechanism on the description.

Re:Attitude Control

[Kymermosst]

The vast majority of amateur rockets are passively stabilized.

Center of gravity above center of pressure.

Qu8k Construction Materials

[kgholloway]

I'm wondering what materials you used to construct your rocket? The sustainer appears to be made from Aluminum with welded on Aluminum fins. However the nosecone appears to be made of two or more materials. Also what did you use for the shade over the video camera that apparently melted during the boost phase?

Hurdles

[Twinbee]

What were some of the hardest hurdles you had to overcome to get this working?

Machinery

[vlm]

I looked at your website pictures; clean shop (cleaner than mine, anyway); Curious what type of equipment you used to build it... I see a bridgeport-style knee milling machine, a large unidentifiable lathe with a quick change toolpost. Chinese or classic American heavy iron? Nice smoke off the carbide (carbide, unlike HSS, can be pushed hard enough to make the cutting oil burn without wearing the cutting edge) Looks like all manual machines, no CNC? TIG welding the aluminum or ? Did you CAD it all up or build as you get parts? Is something like this rocket light enough to manhandle around the shop or are their engine cranes involved, or a custom cradle of sorts?

Plans for a multi-stage version?

[bkmoore]

Are there any plans to build a multi-stage version to reach even greater altitudes?

Re:flight control

[FlyingGuy]

All of the big high altitude rockets have on-board computers and most have video cameras etc. On launch they go off a rail since there are no active flight controls. The accelerate at well over 10g so they are up to speed very very quickly. Once they clear the rail they can drift but at the speeds they are going up at not so very much. Almost all the drift occurs before apogee as it is coasting or at apogee as the rocket noses over and start the trip back down. Additionally for those kind of launches you wait for the least amount wind possible.

Most of these types of rockets transmit telemetry on HAM frequencies. The operator can watch real time events from the on-board computer for altitude, speed, chute deployment, location ( from the on-board GPS ), ascent stage separation, sustain stage ignition signal, sustain stage burning and all sorts of things.

As the computer detects altitude decreasing and sufficient speed has been attained the computer deploys a drogue parachute which has just enough drag to keep the nose pointed straight down so the rocket accelerates to terminal velocity very quickly.

At a preset altitude either the main chute is deployed or another larger drogue to decelerate the rocket to a speed where the main recovery chute will then deploy without either shredding or tearing the rocket to bits.

Most model rocket engines ( like an estes ) have a small charge at the top of the motor which has a time delay fuse that is lit when the motor ignites. The charge is then ignited which has just enough pressure to cause the two halves of the rocket to separate and deploy the recovery parachute at or just passed apogee so if you have any amount of wind aloft your rocket will ride the wind as it descends at from 2000 or so feet if you have a slow descent it could drift quite a ways.

Rockets like the one in question are very expensive to build and the cost can push up to $5K to $10K depending on how exotic the materials are. Launching those can easily hit $500.00 per launch or more depending on who your motor builder is and other factors.

Re:GPS

[kimvette]

It's suborbital, not orbital, and it never leaves US airspace, so no.

Re:GPS

[kimvette]

I would imagine it would be the FAI definition of 100km being the recognized boundary of the atmosphere and space, even though the atmosphere doesn't truly end until past 10,000km.