Is it legal for me to use an active control system on my high powered rocket?

[stantonjtroy]

Sure. Give me a couple days to dig it up. I have it hard copy somewhere in this mess I call my ref library. I'll also try yo dig up an online resource.

Still looking. It was in an Ordinance training manual I got my hands on when I was in the Army. An actual DOD pub circa 1985ish.

 

[jadebox]

For ground testing, you simply neaf to tilt the canard section around centerline and all the fins should remain vertical for reasonablr airframe angles. Your control algorithm does need to limit angle versus velocity to prevent g-load failures at high velocity, but this should also be straight forward.

In practice, if the controls move too slowly or quickly (or too little or too much), you'll run into problems. But, it would be a fun project to do.

For a long time, I've been researching a system like that. But, I want it to just reduce or eliminate the rocket's rolling to provide a better platform for on-board video recording. Eventually, though, I found that larger rockets, built more carefully, are an easier solution to the rolling problem.

I also considered a system like the one described in the paper I cited earlier (https://aeroconsystems.com/tips/Active_Stabilized_rocket_Wyatt.pdf) to be used in one of our "Akavish" (spider-themed) rockets. I was considering using an active thruster method like that to try to encourage the Akavish to land on its feet. But, I finally realized that getting it to land vertically was just half the problem. It would also have to not be moving relative to the ground. That's a tougher nut to crack.

-- Roger

 

[Adrian A]

The easiest way to actively control and correct for vertical flight deviations is to make a forward payload compartment with 2 axled sets of balanced canards and utilize the x- and y- axis tilt sensors to drive the x- and y- tilt controlling servos connected to the canards. The rocket stability will be largely controlled by the rear fins while the foward canards simply pitch the nose over to keep the trajectory vertical. The best part of this is that a single "dumb" control system will control verticallity regardless of number of stages and whether the motor is thrusting or burned out. There is no reason to worry about roll with this control system, so the overall system is much, much simpler mechanically and electronically than other methods.

For ground testing, you simply neaf to tilt the canard section around centerline and all the fins should remain vertical for reasonablr airframe angles. Your control algorithm does need to limit angle versus velocity to prevent g-load failures at high velocity, but this should also be straight forward.

Bob

I've seen some really mechanically complex canard setups that appear to be motivated by a desire to minimize the number of servos to buy or control, or perhaps a fear of control in unwanted directions. But these days servos are really, really cheap and easily available. That's true even for high-quality, strong servos with good bearings and near-zero backlash. So if I were going to make a 4-canard design I would use 4 servos and just attach the canards directly to the servos. But I'm motivated to minimize the number of canards for drag reasons, and to prevent interference with possible 3-pole towers or sets of 3 passive fins. In the last year I've done a lot of aerobatic RC flight with 2-channel flying wings, so controlling 3-DOF attitude with 2 canards doesn't seem too daunting.

 

[jadebox]

... an Ordinance training manual ....

An "Ordinance" manual is where I'd expect to find laws and regulations.

I searched the US Code for the word "rocket" and found 18 hits. Only two of the matches seemed remotely applicable. First there is the definition of a "Missile System Designed to Destroy Aircraft":

(1) In general.— Except as provided in paragraph (3), it shall be unlawful for any person to knowingly produce, construct, otherwise acquire, transfer directly or indirectly, receive, possess, import, export, or use, or possess and threaten to use—

(A) an explosive or incendiary rocket or missile that is guided by any system designed to enable the rocket or missile to—
(i) seek or proceed toward energy radiated or reflected from an aircraft or toward an image locating an aircraft; or
(ii) otherwise direct or guide the rocket or missile to an aircraft;
(B) any device designed or intended to launch or guide a rocket or missile described in subparagraph (A); or
(C) any part or combination of parts designed or redesigned for use in assembling or fabricating a rocket, missile, or device described in subparagraph (A) or (B).

(2) Nonweapon.— Paragraph (1)(A) does not apply to any device that is neither designed nor redesigned for use as a weapon.
​

The second is the definition of a "Destructive Device":

The term “destructive device” means

(1) any explosive, incendiary, or poison gas

(A) bomb,
(B) grenade,
(C) rocket having a propellent charge of more than four ounces,
(D) missile having an explosive or incendiary charge of more than one-quarter ounce,
(E) mine, or
(F) similar device;

(2) any type of weapon by whatever name known which will, or which may be readily converted to, expel a projectile by the action of an explosive or other propellant, the barrel or barrels of which have a bore of more than one-half inch in diameter, except a shotgun or shotgun shell which the Secretary finds is generally recognized as particularly suitable for sporting purposes; and

(3) any combination of parts either designed or intended for use in converting any device into a destructive device as defined in subparagraphs (1) and (2) and from which a destructive device may be readily assembled.

The term “destructive device” shall not include any device which is neither designed nor redesigned for use as a weapon; any device, although originally designed for use as a weapon, which is redesigned for use as a signaling, pyrotechnic, line throwing, safety, or similar device; surplus ordnance sold, loaned, or given by the Secretary of the Army pursuant to the provisions of section 4684 (2), 4685, or 4686 of title 10 of the United States Code; or any other device which the Secretary finds is not likely to be used as a weapon, or is an antique or is a rifle which the owner intends to use solely for sporting purposes.​

Note, in both cases, devices that are not intended to be weapons are excluded from the definitions.

-- Roger

 

[Adrian A]

Thanks, Roger.

Another area of law that might be a problem are FAA regs on UAVs. Perhaps those are not applicable for vehicles operating within a rocketry waiver cylinder, however.

 

[ClayD]

Thanks, Roger.

Another area of law that might be a problem are FAA regs on UAVs. Perhaps those are not applicable for vehicles operating within a rocketry waiver cylinder, however.

I think if you intended to fly it on the normal ballistic profile, the guidance wouldn't change the FAA deffinition from rocket to UAV.

The further you drift from the balistic profile, the closer you get to rocket powered UAV.

That is how i would see it. Still, a rocket powered aircraft with automated guidance, is no more than an R/C rocket plane.

 

[stantonjtroy]

An "Ordinance" manual is where I'd expect to find laws and regulations.

-- Roger

No it isn't. BUT it is a place to find definitions the government uses. Funny but when it comes to anything weapon related the Govt often turns to the military for defininitions and answers. Go figure.

 

[nealkas]

...Still, a rocket powered aircraft with automated guidance, is no more than an R/C rocket plane.

Certainly my take on it.
If I built a Shuttle with r/c flight controls after separation, is it a weapon?
As long as you don't try to chase your kid brother and sister around the yard with it, it really isn't a 'weapon'.

Seriously, with no warhead and no intent and not aiming it at aircraft, proper safety precautions, etc, is it a weapon?

What if I just want to build R/C X-1, X-15 planes that I can fly?

 

[Adrian A]

There have been a lot of possible rules tossed around with regard to first-person-video RC aircraft flights, but the new rule eventually adopted has gotten rid of the altitude limits and a bunch of other stuff that could have affected this topic.

FAA Modernization and Reform Act of 2012
Senate Bill, Section 607(g)
…exempts most model airplanes used for recreational or academic use from any UAS
regulations established by the FAA
Conference Committee Report
Senate bill with modifications… Language including model aircraft for the purposes of sports,
competitions and academic purposes is removed and replaced with ``hobby''. The modified
section includes language requiring that the model aircraft must be operated in a manner that
does not interfere with and gives way, to all manned aircraft. In addition, language that requires
that model aircraft flown within five miles of an airport will give prior notification to the airport
and the air traffic control (ATC), and that model aircraft that are flown consistently within five
miles of the ATC will do so under standing agreements with the airports and ATC. Lastly,
language is added that will ensure that nothing in this provision will interfere with the
Administrator's authority to pursue enforcement action against persons operating model aircraft
who endanger the safety of the national airspace system. In this section the term ``nationwide
community-based organization'' is intended to mean a membership based association that
represents the aeromodeling community within the United States; provides its members a
comprehensive set of safety guidelines that underscores safe aeromodeling operations within the
National Airspace System and the protection and safety of the general public on the ground;
develops and maintains mutually supportive programming with educational institutions,
government entities and other aviation associations; and acts as a liaison with government
agencies as an advocate for its members.
-----------------------------------------------------------------------------
SEC. 336. SPECIAL RULE FOR MODEL AIRCRAFT.
(a) In General.--Notwithstanding any other provision of law relating to the incorporation of
unmanned aircraft systems into Federal Aviation Administration plans and policies, including
this subtitle, the Administrator of the Federal Aviation Administration may not promulgate any
rule or regulation regarding a model aircraft, or an aircraft being developed as a model aircraft,
if--
(1) the aircraft is flown strictly for hobby or recreational use;
(2) the aircraft is operated in accordance with a community-based set of safety guidelines and
within the programming of a nationwide community-based organization;
(3) the aircraft is limited to not more than 55 pounds unless otherwise certified through a design,
construction, inspection, flight test, and operational safety program administered by a
community-based organization;
(4) the aircraft is operated in a manner that does not interfere with and gives way to any manned
aircraft; and
(5) when flown within 5 miles of an airport, the operator of the aircraft provides the airport
operator and the airport air traffic control tower (when an air traffic facility is located at the
airport) with prior notice of the operation (model aircraft operators flying from a permanent
location within 5 miles of an airport should establish a mutually-agreed upon operating
procedure with the airport operator and the airport air traffic control tower (when an air traffic
facility is located at the airport)).
(b) Statutory Construction.--Nothing in this section shall be construed to limit the authority of
the Administrator to pursue enforcement action against persons operating model aircraft who
endanger the safety of the national airspace system.
(c) Model Aircraft Defined.--In this section, the term ``model aircraft'' means an unmanned
aircraft that is--
(1) capable of sustained flight in the atmosphere;
(2) flown within visual line of sight of the person operating the aircraft; and
(3) flown for hobby or recreational purposes.

See the following link for a more legible copy:
https://www.modelaircraft.org/files/HR658_020112.pdf

 

[jadebox]

No it isn't. BUT it is a place to find definitions the government uses. Funny but when it comes to anything weapon related the Govt often turns to the military for definitions and answers. Go figure.

I was just being silly ... picking on you for misspelling "ordnance."

In any case, the definitions embedded in the laws themselves are what count, not what it might say in a field manual.

-- Roger

 

[stantonjtroy]

I was just being silly ... picking on you for misspelling "ordnance."

In any case, the definitions embedded in the laws themselves are what count, not what it might say in a field manual.

-- Roger

I agree completely. No offence taken ( I saw the smiley :wink: ) As for the misspelling, what can I say, My public school education flies into action once again. Spell check was made for guys like me.

 

[jadebox]

Spell check was made for guys like me.

Unfortunately, spell check wouldn't catch that one. It's like "lightening" and "lightning" ... both are properly spelled words, but mean very different things.

I just finished reading a book that not only used the phrase "fast as lightening," it also described the space shuttle deploying its "drag shoot" after landing. I like that ... "drag shoot."

-- Roger

 

[Adrian A]

Following up on another discussion, I took the time to read through the ITAR regs, and what is covered under the munitions list.

https://ecfr.gpoaccess.gov/cgi/t/te...view=text&node=22:1.0.1.13.59.0.31.13&idno=22

https://www.fas.org/spp/starwars/offdocs/itar/p121.htm#C-XII

In section 121.1, category XII, part (d), there is something that might be applicable:

*(d) Inertial platforms and sensors for weapons or weapon systems; guidance, control and stabilization systems except for those systems covered in category VIII; astro-compasses and star trackers and military and [non-military] accelerometers and gyros. For aircraft inertial reference systems and related components refer to Category VIII.

the brackets mean that it's scheduled to be removed from the munitions list.

Category VIII says:

*(e) Inertial navigation systems, aided or hybrid inertial navigation systems, Inertial Measurement Units (IMUs), and Attitude and Heading Reference Systems (AHRS) specifically designed, modified, or configured for military use and all specifically designed components, parts and accessories. For other inertial reference systems and related components refer to Category XII(d).

The question that I can't figure out after reading this is whether inertial navigation systems not designed for a military application, are covered. Category VIII only covers the military ones, but it says to look at category XII for non-military ones. Section XII says for aircraft inertial reference systems, go back to VIII. I'm definitely not a lawyer, but maybe the intent is to cover inertial nav systems if it's for a military aircraft or any non-aircraft application? And would our hobby rockets qualify as an aircraft?

All of the above might put hobby inertial nav systems on the munitions list, but that only prevents U.S. exports, (including technology exports like forum posts), not development or use within the U.S. as far as I know.