Active Flight Control

The Rocketry Forum

Help Support The Rocketry Forum:

ksaves2

Lifetime Supporter
TRF Lifetime Supporter
Joined
Nov 25, 2009
Messages
5,835
Reaction score
239
Did someone actually suggest looping a rocket? :eek: What were they thinking? ^What could possibly go wrong with that?^
This is what can happen. I am embarrassed I helped mix the motor for this rocket and was there when the flight occurred. I was desperately hoping it would make the turn, complete the loop and go up. Ahhh, this wasn’t in the plan. Unfortunately, the flier didn’t try to balance it on a sawhorse and see that it needed nose weight. Sad, very sad. It flew fine on an M and did OK with an N except one of the two chutes tangled and the rocket hit butt end hard. Flier originally did his L3 flight on it with the M at MWP 3 and went to all of 1410 feet. Had 3 chutes on the NC and 3 chutes on the sustainer. On the N flight, flier put only two chutes on the sustainer and one fouled/streamered on deployment that resulted in a hard hit. Flier converted it from a 4 inch motor hole to a 6 inch motor hole a couple of years later so holy molee here we go!!! Sad, very sad. The flier is deceased now and I miss him. Had a heck of a rocket shop. After this and a few more failures he resorted to flying “M” and lower impulse rockets quite successfully before he left this world. I am glad I got to know him. Ummmm, the loop wasn’t in the plan mind you . Kurt Savegnago
 
Last edited:

Richard Dierking

Well-Known Member
TRF Supporter
Joined
Nov 25, 2018
Messages
189
Reaction score
94
Location
Temecula, CA
George makes one of the only systems that helps with a major failure mode for multistage flights. So, he's helping us!
I meant John for his work with MARSA and the tilt module. I haven't used the tilt module yet, but I plan to. I will of course test it first. ;-)
George has made his own contributions to our hobby.
 

Alan15578

Well-Known Member
Joined
Feb 11, 2018
Messages
319
Reaction score
72
There has been a lot of good input here. I deliberately didn't include roll control in the initial writeup because I didn't see either (a) controversy about roll control since it doesn't change the rocket's direction of travel and (b) any particular operational problems that might arise if the roll control system failed. Since the guidance here is to try to reduce controversy and address potential safety concerns, I didn't include it. It could be added, at the cost of increasing the length of the document and maybe raising more questions than it resolves.
That is interesting because about a month ago I came up with a roll control only guidance control scheme. On one of his last posts to this group, our favorite TVC guy, Joe Bernard, mentioned that he had developed a reaction wheel (?) for roll control of his TVC rockets. I have no looked into his device, However, one could design a stable rocket with just enough pitch trim built in that it would be able to corect for wind gusts and launch errors. This might be done with a simple shim to the nose cone alignment. Fins have enormous roll damping, so we might need to stabilize with a ring fin to avoid overwhelming the reaction wheel. Controlling the roll allows the flight direction to be changed, without using any TVC or aerodynamic control surfaces. Control authority would be too meager to effectively fly against targets. The flight would nominally be a spiral, but it would be a spiral going up the center of your waiver cylinder.

I appreciate the desire to have a "document" that you can refer people to. It is so much kinder than just blowing them off or telling them to read the FAQs. Nevertheless, I'd prefer the document was shortened to: Thou shalt not fly sport rockets against targets. The first part of that sentence needs work, but the second part has an almost poetic precision. With just a few words it implies that the target is a real asset of some value and not just a virtual aim point or spot landing marker in the ground. The word against implies the attempt to harm the target, and not just say to photograph it or dock to it.

I think the "document" that might be helpful would be one those obscure NAR non binding "best practices" safety papers. This should not be a exhaustive report, nor a "How To" on the subject. Rather it would be a lessons learned compilation of things that have been proven unsafe.

Alan
Old GNC Guy
 

DaveW6DPS

Well-Known Member
Joined
May 28, 2013
Messages
474
Reaction score
226
Location
Barstow, CA
...I appreciate the desire to have a "document" that you can refer people to. It is so much kinder than just blowing them off or telling them to read the FAQs. Nevertheless, I'd prefer the document was shortened to: Thou shalt not fly sport rockets against targets. The first part of that sentence needs work, but the second part has an almost poetic precision. With just a few words it implies that the target is a real asset of some value and not just a virtual aim point or spot landing marker in the ground...
Why do we need any NAR or TRA rules?
Note 101.23(a)(4). A rocket flight may not create a hazard, whether deliberate or not.

§ 101.23 General operating limitations.
(a) You must operate an amateur rocket in such a manner that it:

(1) Is launched on a suborbital trajectory;

(2) When launched, must not cross into the territory of a foreign country unless an agreement is in place between the United States and the country of concern;

(3) Is unmanned; and

(4) Does not create a hazard to persons, property, or other aircraft.
 

Steve Shannon

Well-Known Member
TRF Supporter
Joined
Jul 23, 2011
Messages
6,307
Reaction score
2,864
Location
Butte, Montana
Why do we need any NAR or TRA rules?
Note 101.23(a)(4). A rocket flight may not create a hazard, whether deliberate or not.

§ 101.23 General operating limitations.
(a) You must operate an amateur rocket in such a manner that it:

(1) Is launched on a suborbital trajectory;

(2) When launched, must not cross into the territory of a foreign country unless an agreement is in place between the United States and the country of concern;

(3) Is unmanned; and

(4) Does not create a hazard to persons, property, or other aircraft.
I don’t think we need any additional rules. I like Boatgeek’s work towards coming up with some helpful clarifying guidelines and I’ll certainly study them more when I have a chance. I haven’t been able to follow along much due to time constraints, but I did see one suggestion from someone that we place a statement in our safety codes saying “Flight controls are permitted.” That is the logical result of not finding prohibitive language in FAR 101 and NFPA 1127 or anywhere else, but that’s all; people still must be familiar with whatever regulations there are. We probably never could adopt a broadly permissive statement like that in our safety codes. Such a broad statement also stands a chance of being incorrect in some of the countries where we have Prefectures. We always require compliance with laws in effect wherever our launches are held, including FAR 101 as you so correctly referenced.
 

Alan15578

Well-Known Member
Joined
Feb 11, 2018
Messages
319
Reaction score
72
Yes, we don't need new rules. I think what is currently on the table is a potential reference document. Kind of a guidance guidance document. We are waiting for Steve to post a follow up. I hope what is developed is a document that helps describe what can be done and not how it is done.

So Allen15578, I'm interested to hear more about your project. I started out just considering how to control roll using 2 control surfaces between fins. The system was going to use the Sun as a reference. See the control system photo that shows the electronics with photocells. Then, I decided to up the game to roll and pitch control. It seemed more practical. The electronics I made will probably never fly. I'm going to switch to an accelerometer and gyro based platform.

Joe Barnard is a smart guy and definitely entertaining. But all the stuff from BPS Space comes to us in a black box. To me, a reaction wheel would work much better on a TVC rocket with no fins than an aerodynamically stable rocket with fins. But, I would really like someone to try this and post some results.

I developed a strategy for my project and I believe anyone that is developing a flight control system needs to test incrementally. First, I made a stable rocket with minimum natural roll. I've seen teams develop roll control systems with little regard with how the rocket normally rolls, and never seen one of these work well. I flew my rocket months ago (things have kind of got delayed from CV), and the results were promising. Rolled about 2 times to just under 10K'. So, I think I can control that. Here's the video (only about 1 min long).

Next flight will have the control surfaces, but keep them in neutral position. Fight 3 will attempt to stabilize roll, and flight 4 is roll and pitch maneuver. And, finally test 5 or 6 is a 2 stage flight. I'm thinking I'll have to tune the system at some point and re-fly. Well, that's the plan!

View attachment 424389
I am not doing a project. I just posted a simple guidance and control concept involving roll control that anyone is free to implement and experiment with.

I am not familiar with BPS beyond what Joe Bernard has posted on TRF. Do you really care if his stuff comes in a black box?;) I have not read of any complaints with the quality of his electronics. I might do some things differently, and worse. He makes a tidy package that saves users the trouble of designing, building, bread boarding, testing, etc. I think Joe is still learning control theory, but there are some people who want to play with flight controls with no apparent interest in learning control theory or even getting a college education.
 

phyzzld

Well-Known Member
TRF Supporter
Joined
Aug 19, 2017
Messages
71
Reaction score
15
Yes, we don't need new rules. I think what is currently on the table is a potential reference document. Kind of a guidance guidance document. We are waiting for Steve to post a follow up. I hope what is developed is a document that helps describe what can be done and not how it is done.

I agree that we don't need new rules, however, to me, a "document that helps describe what can be done" is a rule. On the other hand a document about "how it is done" is exactly what is needed. The "active control" topics people have been discussing here can be complicated, and helping to educate potential users of these technologies is the best way to reduce safety risks. I think Alan has a great idea about making a "best practices" paper.

I've pushed on this because this is the only item in the Safety Code that has regular questions about what the Code means and what is allowed.
boatgeek, your rough draft is a good start but, if your goal is as quoted above, I think it is too specific to be very effective or enduring. As soon as the next cool technology comes out, we'll be having these same threads all over again. Often being specific can answer many questions but raise many others. Finding that compromise is the trick.

Jeff
 

Richard Dierking

Well-Known Member
TRF Supporter
Joined
Nov 25, 2018
Messages
189
Reaction score
94
Location
Temecula, CA
Jeff, perhaps there is a misunderstanding. Frankly, your post is a bit confusing to me. If you want something about how it can be done, that to me is restrictive. If someone wants to do something differently and it's not listed, does the reference document just become longer? Currently there are a handful of projects but in like 5 years there will be hundreds.
I'm thinking that by how, you actually don't mean all the methods and potential failure modes of those methods.

By what can be done, I mean something like:

Active flight control is allowed and people are encouraged to develop and test new systems.

No rocket may be flown with the intention of causing harm or injury to any person or object on the ground or in flight. This is the clear intention of SLP F.1 and K.2. All rockets must follow the TSC and SLP, including planning for safe recovery.
If you have specific questions about flying your new system, please contact the club where you intend to launch your project.

So, not how to do it. How is more of a technical issue. If people have specific questions or concerns about their project, including safety issues, they could ask under a separate post. We need something to point to and reassure people that they can pursue active flight control but must do it safely and not violate the existing regulations.
 

boatgeek

Well-Known Member
Joined
Dec 27, 2014
Messages
2,647
Reaction score
1,067
I agree that we don't need new rules, however, to me, a "document that helps describe what can be done" is a rule. On the other hand a document about "how it is done" is exactly what is needed. The "active control" topics people have been discussing here can be complicated, and helping to educate potential users of these technologies is the best way to reduce safety risks. I think Alan has a great idea about making a "best practices" paper.



boatgeek, your rough draft is a good start but, if your goal is as quoted above, I think it is too specific to be very effective or enduring. As soon as the next cool technology comes out, we'll be having these same threads all over again. Often being specific can answer many questions but raise many others. Finding that compromise is the trick.

Jeff
I agree that the more prescriptive the document is (you should always do _____), the more likely it is to become obsolete. If it's not kept up to date, it'll cause more confusion as people ask why they still have to do ____ when they have this new technology that makes ____ obsolete (see Switches, deployment systems for a recent example). I've tried to stick to principles rather than prescriptions, except in a few places that I thought were important.

I am interested in what you think is too specific to be enduring. I tried not to be specific, but may have missed the mark.

That is interesting because about a month ago I came up with a roll control only guidance control scheme. On one of his last posts to this group, our favorite TVC guy, Joe Bernard, mentioned that he had developed a reaction wheel (?) for roll control of his TVC rockets. I have no looked into his device, However, one could design a stable rocket with just enough pitch trim built in that it would be able to corect for wind gusts and launch errors. This might be done with a simple shim to the nose cone alignment. Fins have enormous roll damping, so we might need to stabilize with a ring fin to avoid overwhelming the reaction wheel. Controlling the roll allows the flight direction to be changed, without using any TVC or aerodynamic control surfaces. Control authority would be too meager to effectively fly against targets. The flight would nominally be a spiral, but it would be a spiral going up the center of your waiver cylinder.

I appreciate the desire to have a "document" that you can refer people to. It is so much kinder than just blowing them off or telling them to read the FAQs. Nevertheless, I'd prefer the document was shortened to: Thou shalt not fly sport rockets against targets. The first part of that sentence needs work, but the second part has an almost poetic precision. With just a few words it implies that the target is a real asset of some value and not just a virtual aim point or spot landing marker in the ground. The word against implies the attempt to harm the target, and not just say to photograph it or dock to it.

I think the "document" that might be helpful would be one those obscure NAR non binding "best practices" safety papers. This should not be a exhaustive report, nor a "How To" on the subject. Rather it would be a lessons learned compilation of things that have been proven unsafe.

Alan
Old GNC Guy
That's an interesting concept for using roll control to provide guidance. My first thought is what happens if the roll control system fails--does the rocket start doing loops? If so, I'm not sure I'm a big fan. Regardless, this system would be covered under the aerodynamic controls section, possibly with the exception of not being stable with the control system inactive. That section could potentially be generalized a bit to account for this type of roll control.

My problem with the "thou shalt not fly against targets" statement is that's exactly what we have now, and there's a lot of confusion about whether any kind of active control is allowed. Perhaps there will always be confusion and I'm tilting at windmills trying to clear it up:).
 

DaveW6DPS

Well-Known Member
Joined
May 28, 2013
Messages
474
Reaction score
226
Location
Barstow, CA
My problem with the "thou shalt not fly against targets" statement is that's exactly what we have now, and there's a lot of confusion about whether any kind of active control is allowed. Perhaps there will always be confusion and I'm tilting at windmills trying to clear it up:).
Forgive me for getting very direct, but you have illustrated the central problem with your tilting at windmills.

No where, except in your posts, do we find the words "Thou shalt not fly against targets."

The regulations and current policies are quite clear, except when people like you and Richard muddy things by claiming there is a problem and then expecting or writing a "solution" that is not an improvement.

There is nothing that says you cannot experiment with, or use, active guidance on hobby rockets.

The rule is you cannot shoot a rocket at people or stuff and must take reasonable specified precautions to prevent accidental damage or injury. That is with or without active guidance. Why is there a need for anything more?
 

Richard Dierking

Well-Known Member
TRF Supporter
Joined
Nov 25, 2018
Messages
189
Reaction score
94
Location
Temecula, CA
Do you really care if his stuff comes in a black box?;) I have not read of any complaints with the quality of his electronics. I might do some things differently, and worse. He makes a tidy package that saves users the trouble of designing, building, bread boarding, testing, etc. I think Joe is still learning control theory, but there are some people who want to play with flight controls with no apparent interest in learning control theory or even getting a college education.
Alan15578, I'm currently working on a rocket that uses Signal R2. Like rocket kits, ready built stuff is great to start out with. But, some people will want open source code so they can collaborate and experiment with different techniques. Others will be perfectly happy to stick with commercial packages. And, I think that's great.

IMG_2742.jpg
 
Last edited:

phyzzld

Well-Known Member
TRF Supporter
Joined
Aug 19, 2017
Messages
71
Reaction score
15
I agree that the more prescriptive the document is (you should always do _____), the more likely it is to become obsolete. If it's not kept up to date, it'll cause more confusion as people ask why they still have to do ____ when they have this new technology that makes ____ obsolete (see Switches, deployment systems for a recent example). I've tried to stick to principles rather than prescriptions, except in a few places that I thought were important.

I am interested in what you think is too specific to be enduring. I tried not to be specific, but may have missed the mark.
I think the amount of specificity used depends on the goal of the document and chances are I have misunderstood your goal. As a practical guide for flyers and RSO's in working with active control of rockets, I think you are spot on. If the goal is to provide "guidance" to flyers about what type of active control activities are allowed, then talking just about TVC, movable control surfaces and parachute recovery could be misunderstood as being restrictive.

The guidance is not intended to be exclusive—systems not described here should be reviewed under the same principles.
This is a general statement but the principles stated while good for a safety analysis, I'm not sure they help clarify whether the system would be allowed to fly more than the current safety code already does.

Just to clarify, what do you believe is lacking in the current code that would require the addition of you document?

Jeff
 

boatgeek

Well-Known Member
Joined
Dec 27, 2014
Messages
2,647
Reaction score
1,067
Forgive me for getting very direct, but you have illustrated the central problem with your tilting at windmills.

No where, except in your posts, do we find the words "Thou shalt not fly against targets."

The regulations and current policies are quite clear, except when people like you and Richard muddy things by claiming there is a problem and then expecting or writing a "solution" that is not an improvement.

There is nothing that says you cannot experiment with, or use, active guidance on hobby rockets.

The rule is you cannot shoot a rocket at people or stuff and must take reasonable specified precautions to prevent accidental damage or injury. That is with or without active guidance. Why is there a need for anything more?
There are absolutely requirements to not fly against targets. TRA and NAR rules may not bear the force of law, but I believe there was a side mention of a similar rule in NFPA, which is. Regardless, most of us fly under TRA or NAR rules, so most launches are governed by their respective safety codes.

Tripoli Safe Launch Practices, 2017, Section K.2: "Do not ignite and launch a rocket horizontally, at a target, in a manner that is hazardous to aircraft, or so the rocket's flight path goes into clouds or beyond the boundaries of the flying field (launch site). "

NAR Model Rocket Safety Code, Item 8: Flight Safety. I will not launch my rocket at targets, into clouds, or near airplanes, and will not put any flammable or explosive payload in my rocket.

NAR HPR Safety Code, Item 9: Flight Safety. I will not launch my rocket at targets, into clouds, near airplanes, nor on trajectories that take it directly over the heads of spectators or beyond the boundaries of the launch site, and will not put any flammable or explosive payload in my rocket. I will not launch my rockets if wind speeds exceed 20 miles per hour. I will comply with Federal Aviation Administration airspace regulations when flying, and will ensure that my rocket will not exceed any applicable altitude limit in effect at that launch site. [underlines in the three items above are mine, bold is in the original]

Like I said a few posts ago, you can set your watch by the threads here where someone starts up a discussion about some kind of flight control and half a dozen people start an argument about whether any kind of guidance is legal. The first two pages of this thread are exactly that, devolving into a discussion about direction control vs. control towards a point in space then pulling in the Munitions List, etc. Maybe that disagreement doesn't really happen in the wider world, but it certainly appears that there isn't a consistent understanding of what launching at targets means.
 

boatgeek

Well-Known Member
Joined
Dec 27, 2014
Messages
2,647
Reaction score
1,067
I think the amount of specificity used depends on the goal of the document and chances are I have misunderstood your goal. As a practical guide for flyers and RSO's in working with active control of rockets, I think you are spot on. If the goal is to provide "guidance" to flyers about what type of active control activities are allowed, then talking just about TVC, movable control surfaces and parachute recovery could be misunderstood as being restrictive.



This is a general statement but the principles stated while good for a safety analysis, I'm not sure they help clarify whether the system would be allowed to fly more than the current safety code already does.

Just to clarify, what do you believe is lacking in the current code that would require the addition of you document?

Jeff
Fair points. One could make it "static or movable control surfaces" and cover most everything. I suppose roll control could be thrown in for good measure. The hole either in the safety codes or our understanding of them is immediately above--can people fly with active controls? There seems to be quite a bit of disagreement about that, though perhaps from just a few people who may not be at all representative of the hobby in general.

I think the "system being allowed to fly" question is way bigger than we can address here. Take for example the issue of starting small. If a 19-year old with 2 L2 flights under their belt came up with a brand new 54mm TVC system intended to fly on an L motor at a 1.1:1 thrust:weight ratio, the RSO could reasonably be expected to be skeptical about whether it flies. If Jim Jarvis came up with a similar flight, the RSO may rightly be a lot less suspicious. Those kinds of judgement calls are really hard to write into specific rules.
 

phyzzld

Well-Known Member
TRF Supporter
Joined
Aug 19, 2017
Messages
71
Reaction score
15
The hole either in the safety codes or our understanding of them is immediately above--can people fly with active controls?
If TRA/NAR has a problem with active control for technical or other reasons (ie, safety, insurance, just don't like it, etc...) then they should explicitly prohibit it. However, if their only concern is whether it violates the law, then that is a question that hopefully will never get answered. Never ask the government for clarification! You just might get it. By not explicitly prohibiting active control they are implicitly approving it. I'm not sure that explicitly approving it would make any difference. What TRA/NAR says only matters to a point anyway. I doubt that "TRA/NAR said its ok" will hold up in court. In the end flyers have to use their best judgement and decide if any potential risk is worth it.

I think the "system being allowed to fly" question is way bigger than we can address here. Take for example the issue of starting small. If a 19-year old with 2 L2 flights under their belt came up with a brand new 54mm TVC system intended to fly on an L motor at a 1.1:1 thrust:weight ratio, the RSO could reasonably be expected to be skeptical about whether it flies. If Jim Jarvis came up with a similar flight, the RSO may rightly be a lot less suspicious. Those kinds of judgement calls are really hard to write into specific rules.
Exactly! I completely agree. We need to trust our RSO's. If RSO's start making bad judgements, then TRA/NAR needs better RSO's, not more rules.

Jeff

P.S. I am NOT implying myself nor implying that boatgeek said RSO's are making bad judgements. The ones I have dealt with do a great job!
 
Last edited:

OverTheTop

Well-Known Member
Joined
Jul 10, 2007
Messages
3,829
Reaction score
1,149
Location
Melbourne Australia
Like I said a few posts ago, you can set your watch by the threads here where someone starts up a discussion about some kind of flight control and half a dozen people start an argument about whether any kind of guidance is legal.
Maybe this thread should be made a sticky? Yes, No, Maybe?
 

Steve Shannon

Well-Known Member
TRF Supporter
Joined
Jul 23, 2011
Messages
6,307
Reaction score
2,864
Location
Butte, Montana
The answer to the repeated question, can we fly with active controls, is:
1. There is no prohibition in either Tripoli Safety Codes or NFPA 1122, 1125, or 1127.
2. Government regulations may vary by country, state or other regional unit, or possibly municipality.
3. At this writing, I know of no federal prohibition in the United States, but ITAR may speak to the sharing of information about such technology. Tripoli cannot advise you on legal matters related to ITAR.
4. It’s up to each flyer to research the laws that apply to their specific situation. Maybe Tripoli could help by compiling a reference as people inform us, but people must realize that laws change and it’s likely any such reference will be imperfect.
 

JimJarvis50

Well-Known Member
Joined
Jan 18, 2009
Messages
2,373
Reaction score
569
The answer to the repeated question, can we fly with active controls, is:
1. There is no prohibition in either Tripoli Safety Codes or NFPA 1122, 1125, or 1127.
2. Government regulations may vary by country, state or other regional unit, or possibly municipality.
3. At this writing, I know of no federal prohibition in the United States, but ITAR may speak to the sharing of information about such technology. Tripoli cannot advise you on legal matters related to ITAR.
4. It’s up to each flyer to research the laws that apply to their specific situation. Maybe Tripoli could help by compiling a reference as people inform us, but people must realize that laws change and it’s likely any such reference will be imperfect.
+1

And I've been told by people who should know that the FAA encourages us to use techniques such as vertical stabilization to stay within the waiver radius. I did a three-stage flight that went to 175K where stabilization was used from the bottom of the second stage during the coast after first stage separation. Stabilization corrected tilt to less than 2°, and without it, tilt would have been much higher at second stage ignition (although it is possible that the rocket would have exceeded the 10° tilt criteria instead). Third stage tilt has to be relaxed due to gyro drift, so in this case, stabilization was the difference between a 3 mile recovery and a 20+ mile recovery.

Jim

Tilt Graph 3.jpg
 

DaveW6DPS

Well-Known Member
Joined
May 28, 2013
Messages
474
Reaction score
226
Location
Barstow, CA
...Maybe that disagreement doesn't really happen in the wider world, but it certainly appears that there isn't a consistent understanding of what launching at targets means.
I have never seen the disagreements occur at launches. Only on forums.

As for what launching at targets" means", I think FAR 101.23(a)(4) is pretty clear.
"Does not create a hazard to persons, property, or other aircraft. "

dead horse 4.gif
 

Not Quite Nominal

Well-Known Member
Joined
Jun 21, 2018
Messages
74
Reaction score
86
As far as I read the rules, the prohibition is on “targets”, not on “guidance”.

Rocket boosted gliders have existed for decades, and they are clearly guided.

You may guide a rocket towards a point in space, so long as it doesn’t hit another object, and you may guide it towards the ground so long as it is no longer flying like a rocket (gliders, parachutes, etc)
 

Richard Dierking

Well-Known Member
TRF Supporter
Joined
Nov 25, 2018
Messages
189
Reaction score
94
Location
Temecula, CA
The graphic that Jim posted was interesting and useful to this topic. The one that Dave posted does not add to this and disparages the whole thread with little regard to actual contributions to this thread and what was discussed.
For me, I will never post anything like this again.
 

jqavins

Joseph Avins
TRF Supporter
Joined
Sep 29, 2011
Messages
3,402
Reaction score
1,055
Location
Howard, NY
Stability is addressed above. My understanding of the 3:1 requirement is that this was intended to assure adequate speed off the rail. Since that's much less of an issue in TVC, it didn't seem like it was necessary. It would be a good idea to talk with the people at BPS or people with a lot of TVC flight experience to see if there's a minimum thrust:weight needed for reasonable flight. In theory, there shouldn't be, but in theory there's no difference between theory and practice.
For TVC, as long as thrust/weight is greater than 1, it should be able to lift-off and fly. Maybe not high nor fast but at least lift off the pad and translate.
There's a minimum necessary thrust to moment of inertia ratio necessary to correct pitch and yaw deviations in a manner that maintains stability. What that minimum ratio is depends on many factors, and don't ask me for specifics until I start studying, designing, and experimenting, which won't be any time soon. But I expect that 1.1 times the rocket weight will not be enough, and I expect that 3 times the rocket weight will be more than enough by quite a bit. Just for a guess, a good number might be somewhere from 1.5 to 2, but I could be way off base.

How about landing under thrust? Methods might be OK at some launches and a complete no-go at others.
EEK! IMHO, blasting the ground with an exhaust plume should never be allowed.

I was thinking a self destruction package (actually just a flight termination system), under the control of the RSO, might be required. But in some instances this "decent" altimeter may be sufficient.
If I'm not mistaken, that would be explicitly forbidden under present rules and probably laws. We're not allowed to fly explosive or pyrotechnic payloads.

Thou shalt not fly sport rockets against targets. The first part of that sentence needs work, but the second part has an almost poetic precision. With just a few words it implies that the target is a real asset of some value and not just a virtual aim point or spot landing marker in the ground.
So, a set of concentric, colored bands mounted to a hay bail is not a target? Ask any archer. For spot landing, "marker" and "target" are synonymous. Which is an example of why clarification is needed.

I don’t think we need any additional rules. I like Boatgeek’s work towards coming up with some helpful clarifying guidelines and I’ll certainly study them more when I have a chance. I haven’t been able to follow along much due to time constraints, but I did see one suggestion from someone that we place a statement in our safety codes saying “Flight controls are permitted.”
I don't like that. I believe that rules need to be definite: "You must do this" or "You must not do that". Sometimes those forms can be mixed with care. But a statement like "You are allowed to do so-and-so if you want to" is bad rule making, in my opinion. Which is another example of why a separate clarification document is needed.

Maybe this thread should be made a sticky? Yes, No, Maybe?
No. This thread is too long and rambly. If a good document is generated (and Boatgeek's is a good start) then it should probably (again, my opinion) go into a new thread, and that one made sticky. And how we'll know when we've reached "a good document" is an open question.
 

Richard Dierking

Well-Known Member
TRF Supporter
Joined
Nov 25, 2018
Messages
189
Reaction score
94
Location
Temecula, CA
No. This thread is too long and rambly. If a good document is generated (and Boatgeek's is a good start) then it should probably (again, my opinion) go into a new thread, and that one made sticky. And how we'll know when we've reached "a good document" is an open question.
I agree. Please keep in mind that the nature of this thread has evolved from the original post and the replies to specifics for my project. To be honest, when first mentioned, I didn't know what made sticky meant. Most of you have a lot more experience on RF than me.

This thread has been good. We have seen new information, like the material that Vern posted and got the opportunity to discuss it and come to some conclusions. How many people have seen that info before this thread? The fact that this thread has been viewed by many people evidences that no federal law presently exist prohibiting active flight control. And, no one mentioned any state laws either.

This will not be the last time you see questions about this come up on RF. Some capable person is going to be told that you can't create guidance systems for rockets on some other forum like Arduino and they are going to end up here. What are you going to tell them? How are you going to react to their questions? Do you wish to start completely over? I don't think anyone should mock their concerns or questions.

I think Steve's post #141 would be a good start on a new thread. But, I don't think it's cool to quote across threads without permission. Additionally, because of Steve's present responsibilities, the scope of his comments might not be what most of us are looking for. So, someone (Boatgeek?) could elaborate on the key points. Sure, there's going to be some controversy, but you have a really good start answering some key questions.
 

Peartree

Cyborg Rocketeer
Staff member
Administrator
Global Mod
Joined
Jan 6, 2009
Messages
4,858
Reaction score
427
Location
Alliance, Ohio
I agree. Please keep in mind that the nature of this thread has evolved from the original post and the replies to specifics for my project. To be honest, when first mentioned, I didn't know what made sticky meant. Most of you have a lot more experience on RF than me.

This thread has been good. We have seen new information, like the material that Vern posted and got the opportunity to discuss it and come to some conclusions. How many people have seen that info before this thread? The fact that this thread has been viewed by many people evidences that no federal law presently exist prohibiting active flight control. And, no one mentioned any state laws either.

This will not be the last time you see questions about this come up on RF. Some capable person is going to be told that you can't create guidance systems for rockets on some other forum like Arduino and they are going to end up here. What are you going to tell them? How are you going to react to their questions? Do you wish to start completely over? I don't think anyone should mock their concerns or questions.

I think Steve's post #141 would be a good start on a new thread. But, I don't think it's cool to quote across threads without permission. Additionally, because of Steve's present responsibilities, the scope of his comments might not be what most of us are looking for. So, someone (Boatgeek?) could elaborate on the key points. Sure, there's going to be some controversy, but you have a really good start answering some key questions.
"Made Sticky" has nothing to do with RF, it just means that, on the forum, it always stays (ie. "sticks") at the top of the forum rather than scrolling down over time and getting lost.
 

Richard Dierking

Well-Known Member
TRF Supporter
Joined
Nov 25, 2018
Messages
189
Reaction score
94
Location
Temecula, CA
"Made Sticky" has nothing to do with RF, it just means that, on the forum, it always stays (ie. "sticks") at the top of the forum rather than scrolling down over time and getting lost.
Thank you Peartree. Who can do that? I recall seeing a checkbox for that somewhere.
BTW: I sent a message about the incorrect way (unintentionally) I deleted posts 123 and 127. Can you assist?
 

Steve Shannon

Well-Known Member
TRF Supporter
Joined
Jul 23, 2011
Messages
6,307
Reaction score
2,864
Location
Butte, Montana
I agree. Please keep in mind that the nature of this thread has evolved from the original post and the replies to specifics for my project. To be honest, when first mentioned, I didn't know what made sticky meant. Most of you have a lot more experience on RF than me.

This thread has been good. We have seen new information, like the material that Vern posted and got the opportunity to discuss it and come to some conclusions. How many people have seen that info before this thread? The fact that this thread has been viewed by many people evidences that no federal law presently exist prohibiting active flight control. And, no one mentioned any state laws either.

This will not be the last time you see questions about this come up on RF. Some capable person is going to be told that you can't create guidance systems for rockets on some other forum like Arduino and they are going to end up here. What are you going to tell them? How are you going to react to their questions? Do you wish to start completely over? I don't think anyone should mock their concerns or questions.

I think Steve's post #141 would be a good start on a new thread. But, I don't think it's cool to quote across threads without permission. Additionally, because of Steve's present responsibilities, the scope of his comments might not be what most of us are looking for. So, someone (Boatgeek?) could elaborate on the key points. Sure, there's going to be some controversy, but you have a really good start answering some key questions.
You have my permission to quote my post anywhere else on TRF or in private messages.
 

Latest posts

Top