heaviest G flights

I have a small collection of large, inexpensive, and fun looking rockets I would like to build. The first of note is a nine foot tube used for shipping fancy fishing poles. I am limited to G motors at the field I would like to fly it at.

What are the heaviest rockets people are launching on the venerable G64 white lightning reload and G80 blue thunder singles? I do not care much about altitude but a safe flight is important.

I have flown my Fantazia Crayon Bank conversions on G64s and G76s, however electronic deployment is needed as the delays almost not short enough. The chute deploys with motor delay at about 50' and the rockets fly to just over 500'. Each of the Crayons weighs about 65-69 oz.

Check out the dims and mass of the venerable Aerotech Mirage-I flew a ton of "G" motors thru that one. May match up or be close with your fishing pole shipping tube. Also look at the new G-80 SU motors.

https://www.thrustcurve.org/guidepage.jsp seems pretty helpful.

the rule of thumb is 5 to 1 average thrust to weight, so a G64 would be 64 / 5= 12.8 newtons = 2.88 pounds. G80 = 3.6 pounds. The motor manufacturer also provides a maximum safe liftoff weight. of course there are always conditions where these rules do not apply...

Don't forget you are limited to 3.3 lbs without a waiver.....

tab28682 said:

Don't forget you are limited to 3.3 lbs without a waiver.....

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At the site in question, we actually have a waiver for weight, just not for propellent weight or impulse...

I flew two rockets this weekend on CTI G68Ws, which have less initial thrust than a G64. It was fairly calm conditions but both of these worked fine:
4" BAR Crayon, ~40 oz empty, hit 625 feet on the G68, I used electronic main at apogee with an 8 second backup
4" Madcow Cowabunga, ~50 oz empty, no altimeter but 6 second delay was too long, still deployed safely

SCrocketfan said:

At the site in question, we actually have a waiver for weight, just not for propellent weight or impulse...

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You may want to check your reference on that. There is a use agreement with NASA; I'm less sure about the waiver.

Ari.

RKeller said:

the rule of thumb is 5 to 1 average thrust to weight, so a G64 would be 64 / 5= 12.8 newtons = 2.88 pounds. G80 = 3.6 pounds. The motor manufacturer also provides a maximum safe liftoff weight. of course there are always conditions where these rules do not apply...

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After the initial spike, the first 0.75secs of the G64's thrust curve is above 80 newtons so for launching and getting up to speed you could likely go with heavier than 3 pounds.

The other way to do it is to model it in open rocket or rocksim, put in the actual length of your launch rod/rail and see what your airspeed is at the point you clear the launch system.

Zebedee said:

After the initial spike, the first 0.75secs of the G64's thrust curve is above 80 newtons so for launching and getting up to speed you could likely go with heavier than 3 pounds.

The other way to do it is to model it in open rocket or rocksim, put in the actual length of your launch rod/rail and see what your airspeed is at the point you clear the launch system.

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Very good point! I check the open rocket rail speed on every flight I do. seems I'm either worried it's too low, or want to see how high it is

The Pod Rocket is 64 oz without the motor! Yikes!

I've flown it on G motors before, but it really prefers an H. On G motors, it just lobs up there to around 300 feet, which is kind of weird to see for a rocket that size. Optimum delays are under 4 seconds, so every flight on a single use G with a fixed 4-second delay is a slight risk. I've stopped flying it at Moffett for fear of damage. The interesting thing about that particular rocket is that it seems to come of the rail nice and solid, even when the speed off the rail is kind of slow.

My feeling for Moffett is that something like a G-Force is about as big as you can go in terms of the size of the rocket --- 4" diameter, about 5' tall and built light. (And it is a lot of fun to bring a rocket that big to the LPR launches, because it really Wows the kids!) I've seen taller rockets, but they were smaller diameter. What is the diameter and weight of your fishing pole tube?

I regularly fly a 5.5" MiniMag at Moffett. I use 1G38mm CTI motors which are almost full Gs. I get about 500'. I build relatively light.

It does get the kids' attention.

Ari.

iter said:

You may want to check your reference on that. There is a use agreement with NASA; I'm less sure about the waiver.

Ari.

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With the current CA rules, without clearance we'd be limited to 500 grams. I'm not sure if Moffett has an actual waiver, but we can definitely fly rockets above 500 grams.

How much does your Mini Magg weigh? Mine has 1/4" fins and nose weight so it can't fly G's but I'd be interested to know how much a lightly built one weighs. It is a great attention getter at Moffett.

iter said:

I regularly fly a 5.5" MiniMag at Moffett. I use 1G38mm CTI motors which are almost full Gs. I get about 500'. I build relatively light.

It does get the kids' attention.

Ari.

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That's a fun rocket, and the Magg does do well at Moffett. I like how you even found pink tape for the flight card and igniter!

I've been unclear as to the rules for motors at Moffett, and I have heard conflicting info from different sources. The general rule of thumb is that you can't fly anything over a G. But there are other rules too. One club officer told me that any motor designated as high power, regardless of impulse class, is prohibited. So for example a 2-grain 29mm CTI G88 would be prohibited because the average thrust is over 80 N, even though it is actually not a very big G in terms of impulse. Others have told me that the propellant weight cannot exceed 62.5 grams, so that eliminates the CTI 3-grain 29mm motors, which have about 80 grams, even though their average thrust may be less than 80 N. I'd like to fly the high-thrust, full G CTI motors I've purchased, because it would make some of the larger rockets practical at Moffett, but as far as I know, we aren't really supposed to.

SCrocketfan said:

With the current CA rules, without clearance we'd be limited to 500 grams. I'm not sure if Moffett has an actual waiver, but we can definitely fly rockets above 500 grams.

How much does your Mini Magg weigh? Mine has 1/4" fins and nose weight so it can't fly G's but I'd be interested to know how much a lightly built one weighs. It is a great attention getter at Moffett.

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Mine has 1/8" fins and no nose weight. Like the man says, simplificate and add lightness.

Ari.

ThirstyBarbarian said:

That's a fun rocket, and the Magg does do well at Moffett. I like how you even found pink tape for the flight card and igniter!

I've been unclear as to the rules for motors at Moffett, and I have heard conflicting info from different sources. The general rule of thumb is that you can't fly anything over a G. But there are other rules too. One club officer told me that any motor designated as high power, regardless of impulse class, is prohibited. So for example a 2-grain 29mm CTI G88 would be prohibited because the average thrust is over 80 N, even though it is actually not a very big G in terms of impulse. Others have told me that the propellant weight cannot exceed 62.5 grams, so that eliminates the CTI 3-grain 29mm motors, which have about 80 grams, even though their average thrust may be less than 80 N. I'd like to fly the high-thrust, full G CTI motors I've purchased, because it would make some of the larger rockets practical at Moffett, but as far as I know, we aren't really supposed to.

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IANAL. With that in mind, two rules get consistent enforcement at Moffett: No motor may exceed 160Ns of impulse, and no motor may be sparky. Neither of these will fly there. The club even prints the 160Ns limit on flight cards.

As far as other rules, in my experience: occasionally there are debates about average impulse like you mention, although this humble narrator is unaware of any actual restrictions as long as the flier has HPS certification (NFPA requires certification to buy or fly motors over 80N avg thrust, you need L1 for F240). I've never heard of a 62.5g limit at Moffett. 125g limit came up once, but I'm unaware of any flights grounding on total propellant weight.

Ari.

ThirstyBarbarian said:

That's a fun rocket, and the Magg does do well at Moffett. I like how you even found pink tape for the flight card and igniter!

I've been unclear as to the rules for motors at Moffett, and I have heard conflicting info from different sources. The general rule of thumb is that you can't fly anything over a G. But there are other rules too. One club officer told me that any motor designated as high power, regardless of impulse class, is prohibited. So for example a 2-grain 29mm CTI G88 would be prohibited because the average thrust is over 80 N, even though it is actually not a very big G in terms of impulse. Others have told me that the propellant weight cannot exceed 62.5 grams, so that eliminates the CTI 3-grain 29mm motors, which have about 80 grams, even though their average thrust may be less than 80 N. I'd like to fly the high-thrust, full G CTI motors I've purchased, because it would make some of the larger rockets practical at Moffett, but as far as I know, we aren't really supposed to.

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There is definitely conflicting information. I've checked and motors with greater than 80 N average thrust definitely ARE allowed, but not anything over 62.5 grams of propellent. I've flown G126s, G83s, and G250s without problems, the G88 should be fine. Sparkies are definitely banned.

Ari, I heard that there is a 62.5 gram propellent limit, I'm not sure why. Some of the 38mm 1G motors and all of the 29mm 2G motors are under the limit. What confuses me is I can't find any reference to there being a 62.5 gram limit anywhere besides Moffett, but it definitely exists as Aerotech makes many G motors under that limit.

SCrocketfan said:

Ari, I heard that there is a 62.5 gram propellent limit, I'm not sure why. Some of the 38mm 1G motors and all of the 29mm 2G motors are under the limit. What confuses me is I can't find any reference to there being a 62.5 gram limit anywhere besides Moffett, but it definitely exists as Aerotech makes many G motors under that limit.

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Motors over 62.5g of propellent are class 1.3 explosives. There were proposals to make that the limit for FAA Class I rocket, but FAR Part 101 adopted 125g as the limit.

Ari.

iter said:

Motors over 62.5g of propellent are class 1.3 explosives. There were proposals to make that the limit for FAA Class I rocket, but FAR Part 101 adopted 125g as the limit.

Ari.

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Thanks! That makes more sense.

It would be great if LUNAR would just publish the Moffett rules in a clear and unambiguous way. If I recall correctly, it was Dave Raimondi who told me any motor that is designated as HPR for any reason, including having over 80 N average thrust is not allowed. I asked him about the CTI G reloads I had just bought, and his answer was something along the lines of, "It says HP on the packaging, right? That means it is high power. Don't bring it to Moffett!" I know I had seen higher thrust F and G motors used at Moffett, so obviously that rule is not consistently enforced, but I didn't want to argue the point with him. I'm pretty sure if you put a higher thrust HP full G motor in your rocket and checked it in, many of the RSO's would just let it go. My only concern would be that if something went wrong, and there was an insurance claim, could it be denied based on the fact that the flight was outside the rules. One of the great things about flying with the club is the insurance coverage, and it would be no fun to find out that coverage was not in force because the motor violated the club's ambiguous and poorly understood rules.

ThirstyBarbarian said:

It would be great if LUNAR would just publish the Moffett rules in a clear and unambiguous way. If I recall correctly, it was Dave Raimondi who told me any motor that is designated as HPR for any reason, including having over 80 N average thrust is not allowed. I asked him about the CTI G reloads I had just bought, and his answer was something along the lines of, "It says HP on the packaging, right? That means it is high power. Don't bring it to Moffett!" I know I had seen higher thrust F and G motors used at Moffett, so obviously that rule is not consistently enforced, but I didn't want to argue the point with him. I'm pretty sure if you put a higher thrust HP full G motor in your rocket and checked it in, many of the RSO's would just let it go. My only concern would be that if something went wrong, and there was an insurance claim, could it be denied based on the fact that the flight was outside the rules. One of the great things about flying with the club is the insurance coverage, and it would be no fun to find out that coverage was not in force because the motor violated the club's ambiguous and poorly understood rules.

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I agree, it's really confusing. I've been told HPR G's are allowed. Also, where does this leave motors like the G54RL which is clearly over 62.5 grams of propellent but not HPR? Also in California right now I think technically any reloadable motor is HPR. I have a feeling this might be a bit like your L2 cert question.

I saw a G83 Blue fly at Moffett this weekend, and it definitely seems like HPR G's under the propellent limit are allowed, but I'll check before the next launch.

SCrocketfan said:

I agree, it's really confusing. I've been told HPR G's are allowed. Also, where does this leave motors like the G54RL which is clearly over 62.5 grams of propellent but not HPR? Also in California right now I think technically any reloadable motor is HPR. I have a feeling this might be a bit like your L2 cert question.

I saw a G83 Blue fly at Moffett this weekend, and it definitely seems like HPR G's under the propellent limit are allowed, but I'll check before the next launch.

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I agree that it might be like the L2 cert question --- there are the official rules... and then there might be a few unofficial rules on top of that, depending on who you ask.

This kind of thing should not be like when you are a kid --- Mom says no, so you go ask Dad!

If something went wrong, you've already lost, with or without insurance coverage.

The exchange you describe reminds me of what we called a kit-bag question in Basic Training. Sergeant calls for platoon to assemble. A recruit inevitably asks, "with the kit-bags or without?" The sergeant considers the question. "Well, now that you mention it, bring your kit-bags. Extra exercise is good for you"

Ari.

watermelonman said:

I have a small collection of large, inexpensive, and fun looking rockets I would like to build. The first of note is a nine foot tube used for shipping fancy fishing poles.

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So what are the dimensions and weight of the tube? ASP makes one that's 10' and it flies on D's and E's (however I'm sure it's much lighter than your tube):
https://www.asp-rocketry.com/ecommerce/Tall-Boy-Model-Rocket-Kit.cfm?item_id=584&parent=10&navPanel=

SCrocketfan said:

I agree, it's really confusing. I've been told HPR G's are allowed. Also, where does this leave motors like the G54RL which is clearly over 62.5 grams of propellent but not HPR? Also in California right now I think technically any reloadable motor is HPR. I have a feeling this might be a bit like your L2 cert question.

I saw a G83 Blue fly at Moffett this weekend, and it definitely seems like HPR G's under the propellent limit are allowed, but I'll check before the next launch.

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I can speak to some degree of authority on Moffett rules. The conflicting information comes from our dealing with property owners that do not much understand or like any amount of rockets, but they are accepting for the time being. They do not know or care about NAR designations for which F or G classifies as what, they simply want low power and safety. Also it has proven extremely difficult to get another launch site in the bay area. We err on the safe side. They do not want high power in any way, so we abide. They do not want us breaking 1000 feet, so we abide.

The point has never been to measure grams of propellant, follow arbitrary motor distinctions, or creep up to the waiver. If you have any question about a given motor or flight, simply do not fly it at that site, and save it for Snow Ranch or TCC. Of course I say this as someone who has busted the waiver, but I took my scolding and will not do it again.

Any G motor with >80N average impulse is a HP motor and will carry a CSFM rating accordingly. When flying such motors, we need to follow the NAR high power safety code which specifies 100' minimum personnel distance for a non complex rocket. I haven't paced it off lately and there is some variation from setup to setup, but I would think that sometimes pads 19-24 will have people at them and be less than this minimum distance.

As to the reloadable is a HP motor in CA issue, I hope that the legislation will soon be completed aligning us with NFPA 1125. In the meantime, I note that all of my Aerotech reloads carry the CSFM model rocket seal and would happily show that to anybody requesting evidence as to classification.

I agree with the idea that the point is not to creep up on the limits of the rules, also that there may be rules imposed by the landowner that are more strict than the law, and there may be reasons like the pad configurations that mean HPR G motors are not allowed. I have no problem with any of that. My point is that none of these rules are written down anywhere. All I can find in any of the LUNAR info posted on the website is that the ceiling is 1,000 feet, drift is 500 feet, and motors are A - G impulse class (<160Ns).

You can't rely on the idea that if members have any doubt, then they shouldn't bring the motor, because that level of doubt is going to be different for everyone. And there will probably be a lot of people who will take the kit-bag approach Ari mentioned --- don't ask if there are any unspoken rules unless you want to have them imposed on you. In fact that is the approach most people probably will take, because most Americans are used to the idea that if something is not explicitly prohibited, then it is allowed.

If the club has rules, then the rules should be clear. I'm still not sure if these are really the rules or not, but if so, then here's an example of how I would expect it to be spelled out so that there would be no confusion:

• Altitude is limited to 1,000 feet. If your rocket will go above 1,000 feet with the motor you have selected, choose a smaller motor.
• Drift is limited to 500 feet. If your rocket will drift more than 500 feet with the wind conditions or the parachute you have selected, choose a smaller motor, and/or a smaller parachute, and/or a different rocket.
• Motors are limited to less than 160 Newton-Seconds total impulse. For example, only certified A through G impulse class motors are allowed.
• Motors are limited to 80 Newtons average thrust. For example, a G80 motor is allowed, but a G88 or F120 is not.
• Motors are limited to 62.5 grams of propellant. For example, CTI 2-grain 29mm motors with less than 62.5 grams propellant are allowed, while CTI 3-grain 29mm motors with more than 62.5 grams propellant are not.
• "Sparky" motors are not allowed. For example, motors with Dark Matter, Metal Storm, or Skidmark propellant are not allowed.
• Only motors certified by the California State Fire Marshall are allowed. For example, Loki brand motors that are not CSFM certified are not allowed. Experimental or home-made motors are not allowed.

Again, I do not know if these really are the rules --- these are just a few things I've heard at different times, although I am certain I have attended Moffett launches where fights have been outside these limits. And I even hesitate to make the suggestion to clarify in this way, for the kit-bag reason. But if the landowner has rules or NAR insurance has rules, then something that spells out the rules is the best way to make sure they are followed.

I agree that our limits should be more explicit, but am glad that you see my point. I will bring it up the next meeting.