Good thing to attach to your range box if you’re flying complex configurations or >E power.I don’t have too much to add about changing anything. But the current rules are laid out as simply as they an be, IMO, in the document SecondRow attached to post #14 here.
Down here it is called Young Farmers. I was a member for a number of years quite a while ago too. Fun times.I was a 4H member more than a little while ago. I really liked it.
The regs/ codes are what they are. I would like to know how weight got involved with determining what is a MPR and HPR Flight It isn't about KE or altitude. I simmed a Zephyr with a G-78 making total weight at 53.9 oz.= 190ft/sec to 595ft. KE=2,567J Thats a HPR Flight according to what Simon says. I simmed an Aerotech Arreaux with a G-80 total weight 16.5 oz. = 770ft/sec to 3095ft. KE=12,882J. This is a MPR Flight according to what Simon says. I don't care what anybody says Simon is F'ed up. The one and only reason weight is involved is because Simon says so. No reasoning behind it what-so-ever, nothing to do with safety. It is BSBased on the original wording:Back to OP's problem. Let's say the Zephyr weighs 48.0 oz. w/o motor. Using the G-78 (4.4 oz.) total weight comes to 52.4oz.
it seems like the 48.4 oz weight included the motor; is that right? With a limit of 52.9 oz, you'd have needed 4.5 oz of paint and dog barf to go over the line. I'd bet you squeaked under, but I sure wouldn't bet much.Apogee Zephyr on a G78
Based on what I can find online this would have weighed 48.4 oz plus paint and dog barf. I think we probably hit 53 oz with this one.
Anyway, if you did go over, it was an honest mistake and water under the bridge. Don't sweat it.
I doubt that. There are HPR motors and there are HPR flights. Well, no, actually it's all about HPR flights, and one criterion for that is the use of motors with certain characteristics, which we call HPR motors for convenience. "HPR motors" are defined by four clear lines: total impulse, propellant mass, average thrust, and sparks. HPR flights are defined by greater impulse, thrust, and propellant mass limits that only come into play when clusters or staging are involved; the presence of an "HPR motor"; and lift-off weight. Assuming that there is a good reason for each of those requirements, I don't think there's any room to state the rules more simply than the clear and unambiguous way they are already stated. Any attempt to cover every edge case would make the rules more complicate, not less.Obviously I understand regulations exist for a reason and they should be followed, but it does seem like there's some room for a motivated individual or group to clarify and simplify the regulations.
An attempt to eliminate the edge cases would have to make the rules too restrictive, since they would have to one limit or another value very low in order to assure that other unsafe stuff can't occur. You could, for example, reduce it to "An HPR is any rocket launching with total impulse higher than 120 Ns or any sparky motor." That would, by force, also eliminate single motor impulse, total propellant mass, and average thrust greater than what's currently allowed, since you really can't exceed any of those without going over 120 Ns. But it would also eliminate many cases that are and should be MPR today.
What does that mean, it flies "under HPR rules" but you don't need a cert. "You need a cert" is the essence of HPR rules.Even if that rocket needs to be flying under HPR rules no need to have a HPR cert when using a MPR motor in it.
NAR or Tripoli membership is proof of nothing except having paid NAR or Tripoli dues.G motors above 80Ns average thrust could be sold to members of NAR, Tripoli...
All it means is that in some edge cases, what's typically and conveniently called an "MPR motor" can power an HPR flight. Again, there are parties that ought to do a better job of communicating that, but I don't see why it's basically confusing.Mixing up the weight of a rocket with motor total impulse and motor average impulse, means sometimes they are MPR and other times they turn into HPR all what makes it confusing.
It only looks like BS if you think it's all about the motor, and all about the letter. But it's really all about the flight. H motors and up are called "HPR motors" because if you use one it's certain that you're doing an HPR flight; not using one doesn't mean you're not doing an HPR flight.It is just my opinion that a G impulse should be a G period and be able to fly as a MPR and not be called a HPR motor also under certain circumstances. Sparky G's, G's with 80+Ns average thrust, and G's in a rocket that weighs over 53oz. are all considered HPR. = BS.
-- Joe
NAR #92184
When you judge someone, remember this: how they treat others is the only thing that matters.
I don’t know the history of how weight became a determining factor, but if you calculate the terminal velocities and kinetic energy of two rockets which are identical except for weight during ballistic (no ejection) descent. You may see a situation where weight makes a difference.The regs/ codes are what they are. I would like to know how weight got involved with determining what is a MPR and HPR Flight It isn't about KE or altitude. I simmed a Zephyr with a G-78 making total weight at 53.9 oz.= 190ft/sec to 595ft. KE=2,567J Thats a HPR Flight according to what Simon says. I simmed an Aerotech Arreaux with a G-80 total weight 16.5 oz. = 770ft/sec to 3095ft. KE=12,882J. This is a MPR Flight according to what Simon says. I don't care what anybody says Simon is F'ed up. The one and only reason weight is involved is because Simon says so. No reasoning behind it what-so-ever, nothing to do with safety. It is BS
Having to cert L1 to fly a MPR motor is BS no matter what the weight of the rocket/ flight /whatever. Exceptions can be made.
And Hybrids.Based on the original wording:
it seems like the 48.4 oz weight included the motor; is that right? With a limit of 52.9 oz, you'd have needed 4.5 oz of paint and dog barf to go over the line. I'd bet you squeaked under, but I sure wouldn't bet much.
Anyway, if you did go over, it was an honest mistake and water under the bridge. Don't sweat it.
I doubt that. There are HPR motors and there are HPR flights. Well, no, actually it's all about HPR flights, and one criterion for that is the use of motors with certain characteristics, which we call HPR motors for convenience. "HPR motors" are defined by four clear lines: total impulse, propellant mass, average thrust, and sparks. HPR flights are defined by greater impulse, thrust, and propellant mass limits that only come into play when clusters or staging are involved; the presence of an "HPR motor"; and lift-off weight. Assuming that there is a good reason for each of those requirements, I don't think there's any room to state the rules more simply than the clear and unambiguous way they are already stated. Any attempt to cover every edge case would make the rules more complicate, not less.
An attempt to eliminate the edge cases would have to make the rules too restrictive, since they would have to one limit or another value very low in order to assure that other unsafe stuff can't occur. You could, for example, reduce it to "An HPR is any rocket launching with total impulse higher than 120 Ns or any sparky motor." That would, by force, also eliminate single motor impulse, total propellant mass, and average thrust greater than what's currently allowed, since you really can't exceed any of those without going over 120 Ns. But it would also eliminate many cases that are and should be MPR today.
What does that mean, it flies "under HPR rules" but you don't need a cert. "You need a cert" is the essence of HPR rules.
NAR or Tripoli membership is proof of nothing except having paid NAR or Tripoli dues.
All it means is that in some edge cases, what's typically and conveniently called an "MPR motor" can power an HPR flight. Again, there are parties that ought to do a better job of communicating that, but I don't see why it's basically confusing.
It only looks like BS if you think it's all about the motor, and all about the letter. But it's really all about the flight. H motors and up are called "HPR motors" because if you use one it's certain that you're doing an HPR flight; not using one doesn't mean you're not doing an HPR flight.
I agree but the results of being hit by one weighing 53oz. or 63 oz. would the same. I wouldn't want to be hit by a LPR flight weighing 4 oz. or any one for that matter. Having a HPR cert isn't going to stop a ballistic recovery. Through out the history of model rockets the safety codes have done an excellent job of protecting us and property from ballistic recoveries. As far as I know, no aircraft have ever been hit by a model rocket.I don’t know the history of how weight became a determining factor, but if you calculate the terminal velocities and kinetic energy of two rockets which are identical except for weight during ballistic (no ejection) descent. You may see a situation where weight makes a difference.
The regs/ codes are what they are. I would like to know how weight got involved with determining what is a MPR and HPR Flight It isn't about KE or altitude. I simmed a Zephyr with a G-78 making total weight at 53.9 oz.= 190ft/sec to 595ft. KE=2,567J Thats a HPR Flight according to what Simon says. I simmed an Aerotech Arreaux with a G-80 total weight 16.5 oz. = 770ft/sec to 3095ft. KE=12,882J. This is a MPR Flight according to what Simon says. I don't care what anybody says Simon is F'ed up. The one and only reason weight is involved is because Simon says so. No reasoning behind it what-so-ever, nothing to do with safety. It is BS
Having to cert L1 to fly a MPR motor is BS no matter what the weight of the rocket/ flight /whatever. Exceptions can be made.
I don’t know the history of how weight became a determining factor, but if you calculate the terminal velocities and kinetic energy of two rockets which are identical except for weight during ballistic (no ejection) descent. You may see a situation where weight makes a difference.
Calculate the momentum at terminal velocity as well. The energy and the momentum both matter. A one pound object travelling at 100 ft/s has the same energy as a four pound object at 50 ft/s, but I'd rather be hit by the lighter one (even thought they would both suck a lot).I figured KE could be about the only reason other than just because Simon says so. KE seems not to be the reason.
Ah, now there you have an excellent point. FAR, NFPA, and FAA rules are OK as is (IMO) but the DoT rules are messed up. But yeah, let's not.Now lets get on to discussing why shipping 1 motor containing 35 grams of propellant needs to be HAZMAT and why a 25 lb. box of motors with <30 grams of propellent each can be shipped non HAZMAT On the other hand lets not!!!
Hmm, I didn't think of that angle. 80 N thrust would allow for 16 N weight, which means about 1.6 kg. And the limit of 1.5 kg leaves a bit of margin. Excellent!Do the math. Even if it wasn’t the way the limit was developed, 1500 grams is a reasonable limit to ensure that a rocket of the highest weight (1500 grams) can still have a 5:1 thrust to weight when using an 80 Newton motor, which is the highest thrust motor allowed in model rockets.
I vaguely recall Future Farmers of America, but that may have been a local high school club, and not the 4H, in any event they should be playing with drones, not rockets. 4H does quite well with rockets.Down here it is called Young Farmers. I was a member for a number of years quite a while ago too. Fun times.
I can't agree more but it is a rule of thumb and not in the safety codes. Lots of variables that can either increase or decrease that ratio needed for a safe flight. I did do the math and stated this in my post #26: What is now considered a G MPR motor is not going to be able to safely fly much more weight than that anyway. This was in response to flying a G in a 53 oz. rocket.Do the math. Even if it wasn’t the way the limit was developed, 1500 grams is a reasonable limit to ensure that a rocket of the highest weight (1500 grams) can still have a 5:1 thrust to weight when using an 80 Newton motor, which is the highest thrust motor allowed in model rockets.
I totally agree, I don't think it's really an argument though, just a healthy discussion. What it all boils down to for me is the fact that to be 100% legit OP needs to cert level 1 in order to fly his rocket if it was over 53oz. I just don't see a need for that if using a MPR motor. It would be nice to hear from OP what the actual weight was. I'd bet is was under by a little bit. All done!!But, enough of that. I don't expect we'll come to any agreement, and it's not worth arguing about. The last word is yours if you'd like to have it.
What it all boils down to for me is the fact that to be 100% legit OP needs to cert level 1 in order to fly his rocket if it was over 53oz. I just don't see a need for that if using a MPR motor.
Given that rockets exceeding this limit require an FAA waiver as well,
If I recall correctly, the original NFPA code for model rockets had a total mass (weight) limit, as well as a propellant mass limit. Rockets that massed over the limit were not considered "model" rockets.I don’t know the history of how weight became a determining factor, but if you calculate the terminal velocities and kinetic energy of two rockets which are identical except for weight during ballistic (no ejection) descent. You may see a situation where weight makes a difference.
Not unless you went to high school in South Brunswick, New Jersey.I vaguely recall Future Farmers of America, but that may have been a local high school club...
(I'm prone to occasionally getting caught up in a disagreement until a discussion becomes an argument, and I know I'm not unique in that. I felt like this was starting to head that way.)I totally agree, I don't think it's really an argument though, just a healthy discussion.
All of the versions of NFPA along with all of the justifications for changes are available on the page for the specific NFPA code.If I recall correctly, the original NFPA code for model rockets had a total mass (weight) limit, as well as a propellant mass limit. Rockets that massed over the limit were not considered "model" rockets.
I can't agree more but it is a rule of thumb and not in the safety codes. Lots of variables that can either increase or decrease that ratio needed for a safe flight. I did do the math and stated this in my post #26: What is now considered a G MPR motor is not going to be able to safely fly much more weight than that anyway. This was in response to flying a G in a 53 oz. rocket.
I totally agree, I don't think it's really an argument though, just a healthy discussion. What it all boils down to for me is the fact that to be 100% legit OP needs to cert level 1 in order to fly his rocket if it was over 53oz. I just don't see a need for that if using a MPR motor. It would be nice to hear from OP what the actual weight was. I'd bet is was under by a little bit. All done!!
In my opinion, it is because our community has historically been much more deliberate about self-regulating that we didn't get caught up in the drones-for-christmas overreaction.In my opinion the FAA made things much cleaner when they adopted their current three classes. It’s not perfect; nothing ever is, but the FAA has proven itself very good to work with. Rocketry regulations are much easier to follow than the more recently adopted drone regulations.
With a guesstimate of an additional 25 g for the non-case / non-propellant weight (not sure if the delay and ejection charges count as propellant mass) of the motor
I wouldn’t worry about it too much. There’s nobody hidden behind bushes waiting to bust you for 1505 grams. Thank you for caring and doing the right thing!The rocket is currently with the club's biggest sponsor, but I was able to get the weight of the rocket from them.
It is currently sitting with no dog barf, but all recovery equipment and the motor casing still mounted. That weight is 1386.3 grams.
Assuming based on the data available from the Apogee page where I purchased the motor for the club I can add an additional 59.7 g for the propellant weight so now up to 1446 g.
Don't recall the exact amount of the dog barf, but a 4" diameter cylinder 3" thick gives a volume of .02 ft^3, and using my google skills blown in cellulose insulation stolen from a club members attic weighs 2 lb/ft^3 so add about 18 g for the dog barf. Playing it safe since kids loaded it under supervision and we are now at 1471 g.
With a guesstimate of an additional 25 g for the non-case / non-propellant weight (not sure if the delay and ejection charges count as propellant mass) of the motor and we made it home safely by 4 grams.
Far too close for comfort now that I know the rules.
Ditto.I wouldn’t worry about it too much. There’s nobody hidden behind bushes waiting to bust you for 1505 grams. Thank you for caring and doing the right thing!
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