Rschub
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Thread title was my nickname in high school
Fat n Slow
- Thread starter os_tempore
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os_tempore
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Some really great advise here. I'm not being dissuaded by anything here, so don't worry about that. Some of the atypical looking rockets while cool, I think may detract a bit from the "realism". My kids have been watching rocket videos, so a part of it is if our rocket differs from that significantly I'd be willing to bet they will be less excited - kids and expectations. Due to that, I find it prudent to get a classic rocket shape to keep them engaged.
Likewise, I spoke to a rocket company on the phone and they told me about a few rockets and a motor called a metal storm. After looking them up, I think that would be a good one to go with - very easy to see and track!
For the rocket itself, with everyone's help here and the guys on the phone, I've narrowed it down to just a few. The warlock is out. What's in are these, in no particular order:
1. LOC Bumble Bee - can be flown on a G motor aparently.
2. BMS School rocket
3. Estes Big Daddy
4. AeroTech Sumo
If they're interest doesn't wane in a couple month, I may still get the Warlock and hang it from their rooms ceiling as a goal. Though, I may just do that anyway.
Paint schemes are going to be pink, purple, and white with glitter.
For my own fun, I may turn some parts into CF (and then check the COG again). I'll probably do a build/paint thread if that's a thing on this forum.
I guess the next help I'll need is motor selection. Specifically the smallest motor any of these can use to get off the ground and deploy their parachute safely.
Likewise, I spoke to a rocket company on the phone and they told me about a few rockets and a motor called a metal storm. After looking them up, I think that would be a good one to go with - very easy to see and track!
For the rocket itself, with everyone's help here and the guys on the phone, I've narrowed it down to just a few. The warlock is out. What's in are these, in no particular order:
1. LOC Bumble Bee - can be flown on a G motor aparently.
2. BMS School rocket
3. Estes Big Daddy
4. AeroTech Sumo
If they're interest doesn't wane in a couple month, I may still get the Warlock and hang it from their rooms ceiling as a goal. Though, I may just do that anyway.
Paint schemes are going to be pink, purple, and white with glitter.
For my own fun, I may turn some parts into CF (and then check the COG again). I'll probably do a build/paint thread if that's a thing on this forum.
I guess the next help I'll need is motor selection. Specifically the smallest motor any of these can use to get off the ground and deploy their parachute safely.
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Hey! I resemble that remark!
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I ran cross country in high school. We were all called "bonerunners."
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If Metal Storm is what I think it is, that's a "sparky" motor and requires an L1 cert to buy or fly.
ThirstyBarbarian
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That sounds like a pretty good plan, but I do have a few things for you to consider.
One issue is that Metalstorm motors are another type of motor that require Level 1 certification due to the sparks. Same for anny others that include titanium sponge as an ingredient and spray showers of hot, burning-metal sparks — Dark Matter and Skidmark. They are all awesome motors, but they require certification, even those under the other limits related to thrust, impulse, propellant weight, etc.
At the low altitudes you are talking about, I don’t think you are going to have any trouble tracking these rockets. But I like smoky exhaust trails, so if that’s something you want, then you might like the white and black propellant formulations. There are a few different ones, but typically white propellants make a bright white flame and lots of white smoke, like the old Space Shuttle solid boosters. And black propellants make tons of thick black smoke — so thick you cannot see the motor flame. I forget all the names, but they are things like White Thunder or White Lightning and Black Jack or Fast Jack. Read the propellant descriptions. Ones with a little bit of smoke are the reds and greens. They make smoke, but not much, and are mostly known for flame color. Classic is another with little to no smoke. I think the blues are basically smokeless. Warp 9 makes no smoke. Of all of them, I like the white motors best — nice flame, good smoke, great loud noise.
On the rockets, the school rocket and Big Daddy are good choices.
The Sumo is also good. One thought though is if you really want a “big as a kid” rocket, the Sumo has a big brother that is almost the same rocket but longer — the G-Force. It’s designed to be flown on Aerotech single-use G motors. I loved mine. That was one I would take to low power launches and amaze the kids. It was taller than most of them, and on a G motor, it kept well below the club height ceiling. Some motors put it up only about 500’, which is low for a rocket that size. You could probably fly it even lower on a high-thrust F, like an F67 — you’d have to run a simulation to be sure.
The Bumble Bee seems like it might be right on the edge. Typically rockets end up a bit heavier than the manufacturer’s estimated weight. That one says 48oz. You have only 53oz to work with to avoid requiring an FAA waiver, including the motor and everything else that goes inside the rocket. The fully loaded rocket on the launch pad must be below 53oz. I’ve never built one of these, so I don’t know how close you will be cutting it, but it seems close.
Anyway, it seems like you are on the right track. Keep us posted!
os_tempore
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I saw something about that after I looked it up. Maybe something smokey is better.
Rocketjunkie
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Many suggestions are way too far and many require a waiver from the FAA. Start with something like a Fat Boy on a B4-2 (or B4-4). If they are still interested, then get a kit and motors in the mid power range. Watch weight, both on the pad (3.3 lb.) and propellant (125g, 4.4 oz). Any thing larger requires a waiver and if you go above these limits, it's best to fly with a club that has done the paperwork. You will also get to see a wide variety of rockets without the cost of paying for the motors 
Yes Smokey motors are the way, spark motors also may not be allowed at many smaller launch fields as they require mitigation ground measures to keep grass fires from starting; which is why they need a cert to fly.
Estes Mean Machine!
Over 6 feet tall.
D and E motors.
Easy build.
Pretty impressive slow liftoff.
Cheap.
Can build a couple and have a drag race.
Over 6 feet tall.
D and E motors.
Easy build.
Pretty impressive slow liftoff.
Cheap.
Can build a couple and have a drag race.
Sooner Boomer
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Here is a good place to start. This is the Open Rocket simulation file for a variant of the Estes Fat Boy. It has a 24mm motor mount for D13 sized motors. With a D13, it should get to about 800 feet.
Open Rocket is free design and simulation software. The file I've attached lists Balsa Machining Services part numbers. The only thing missing is positive motor retention. I didn't include a motor clip or screw-on retainer.
Open Rocket is free design and simulation software. The file I've attached lists Balsa Machining Services part numbers. The only thing missing is positive motor retention. I didn't include a motor clip or screw-on retainer.
The LOC Bumblebee was formerly the PML Bumblebee, and I do have one. H's are better, but it will fly successfully on G's with short delays. I have flown mine successfully on the Aerotech G67R and G72DM with the delays drilled to the minimum possible value, though those flights were marginal and I'm not eager to try them again. If I'm going to fly that rocket on a G, I usually reach for a Loki G94 Ice Blue, which it actually flies pretty well on, though that one also requires a cert since it's above 80 N average thrust.
Overall, I would not recommend the Bumblebee to someone with no intention of getting a Level 1.
ThirstyBarbarian
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Do you know what yours weighs fully loaded on the pad with a G motor in it? I’m guessing it’s right at the 1,500 gram limit or above.
Not off the top of my head, but it wouldn't surprise me if it was above that limit too.
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os_tempore
Active Member
This is interesting. What is a marginal flight?
I looked up the level 1 certification, I may get one eventually if the kids are into it so I can get the smokey/flashy motors.
That's a personal term for it rather than any kind of official one. In this case, the flights on those motors didn't go very high and were on their way down when the parachute deployed, despite the minimum delay. Still a successful flight, but could very easily go sideways if, say, it was windy enough to cause a severe weathercock or something.
os_tempore
Active Member
OK, it's done. First order is in! Here's what I got.
1x Estes Big Daddy
12x C11-3 motors
1x AeroTech G-force
2x G53JF-5 motors
1x 29/40-120 hardware kit
I'll start to design the launch controller and rail system etc.
Paint scheme is going to be purple, pink, white, all sparkling/glittered.
1x Estes Big Daddy
12x C11-3 motors
1x AeroTech G-force
2x G53JF-5 motors
1x 29/40-120 hardware kit
I'll start to design the launch controller and rail system etc.
Paint scheme is going to be purple, pink, white, all sparkling/glittered.
Good delay choice on the G53JF-5. Sims to about 625 feet if built without a lot of extra weight which you don't need for G and under motors.
Follow the instructions of where to put the Fin epoxy and ignore the thoughts of making it tail heavy for no reason with extra epoxy, it's not a level 2 rocket.
The G-Force in my Build Pile [Retired I am down sizing my rocket fleet] I planed just today going over it to use sheet metal screws to hold the Tube Coupler and nose cone to the body tube instead of gluing them in permanently.
That allows future mods to that section of the rocket. I have been using screws to hold my tubes, nose, and couplers and stuff together in my rockets for decades, just like on model RC airplanes.
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os_tempore
Active Member
That good to hear. From the explanation the R&D guy at aerotech gave me, it seems like this is a the ideal combo for what I'm looking for. The Big Daddy will be the primary rocket (and maybe the super big Bertha) with the G-force being a special occasion rocket for the time being.
Im going to follow the directions, but I might do a final prepaint wrap with some 3K CF I have from another project. I also have a fair amount of 11oz T700 uni I might reinforce the fin bases with.
I'm hoping to not add weight, but structural ingegrity is important, particularly when it's likely going to get hit with something of drop to the deck via little hands. As an added bonus, I will get a little lower hight with the weight I do need to add. Just have to make sure to not more the COG!
I can already see this hobby escalates quickly.
If you plan to use motors that a CF wrap would be needed for, you must build the rocket much different from the instructions and due to the weight increase; then your G53-5 will cause it to eject way low , chute not open in time, and damage the rocket.
Stock you could use an H128 or H135 DMS 29mm motor by putting it in the motor tube and it will have some of the case hang out. Then you put duck tape around the motor and the engine clip that now is not clipping the end of the motor due to the longer motor that sticks out due to the engine clip. Also add some masking tape to the motor and motor tube joint.
If you didn't glue your nose cone in and use two screws instead, you will need to add just a little weight to it , to get you CG back to where it should be and you can do an L1 on the rocket. That way you can take the weight back out for more G motor flights.
I put an H128 RMS into the AeroTech ISQY 2" diameter rocket with the case sticking out, it didn't need nose weight.
It flew really nice and high built stock. Due to lower weight and small diameter, went 2 times as fast as a G-Force would on the same motor.
I understand about dropping it on the deck...
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os_tempore
Active Member
That's good information, thank you. I was thinking of just reinforcing the tail fins and their attachment point, not the reusable motor assembly or inner workings - unless something looks frail.
When you say glue/screw the cone in, can you explain that? What I'm thinking is probably not accurate.
For an L1 cert, if the kids really like rocketing enough, I'll get a different rocket that I purpose built for it - like the warlock! Or, I might just make my own and borrow a few components from the kit. That's far in the future though. The big daddy is a cool kit they can explore and the G-force is hopefully something that awes them. If this whole thing is a dud, I'll just hang them as thought provoking decoration in their play room until the interest strikes again.
lr64
Well-Known Member
11 ounce uni carbon seems kind of overkill unless you want to use your rocket as an axe.
Do NOT glue the nose or coupler. Put sheet metal screws into the body and nose cone for example after you drilled a smaller pilot hole for them to grab into and then self tap. Same with the coupler.
I can take a picture of a LOC 3" Caliber ISP with that setup tomorrow and post here.
os_tempore
Active Member
Im thinking of over the filets on the fin joints. I'd have to measure, but maybe 1.25" of fabric for the length of the fin to the body. Id be surprised if it added 2 ounces (11oz is a yards weight). It's mostly to distribute the fins load to the body instead of letting it stress that small joint.
os_tempore
Active Member
Please do. I'd like to see what it is.
lr64
Well-Known Member
If the .ork file I found is correct, that would still be something like 4 or 5 percent of total mass, before lighting a G53. These things add up, and things only have to be strong enough not to break until the next piece does. If you make a few Which it probably won't at 56 meters per second. (I've gone that fast in a craft without a motor before.) Just how thin are these fins, and how big of a motor are you planning on using? It might not be a bad idea to use a REASONABLE amount of fiberglass or carbon there, but if you make a few more additions like that 11 ounce carbon, you may not have a clean launch without a longer than standard rail. There's a rule of thumb that the thrust should be at least 5 times the weight, and you're barely making 6 g's as it is. IF we can trust OpenRocket and IF you build to the same weight.
More experienced rocket people will know just how seriously to take that rule of thumb.
BTW, I think your estimate is pretty close for a hand layup.
os_tempore
Active Member
I'm still learning rule of thumb. My first foray into rocketry was my first post on here.
I'll precut and weigh it. The 11oz is the final weight after ideal resin ratio if infused for 1 square yard of fabric. You can do a hand layup and add as much wgt as you want via resin. I'm imagining I'll vacuum the precuts and use them like that instead of vacuuming them on the rocket - way too much work for too little effect. Now if I were doing a whole body and fins all in one shot, that'd be worth a bit vacuum layup.
What does this mean? "If you make a few Which it probably won't at 56 meters per second. (I've gone that fast in a craft without a motor before.)"
The t slot post I'm using is going to be 8ft x1.5". Have to order it still. But the again the rockets aren't here yet either.
Food for thought-
The Big Daddy’s pretty much a blank canvas, but Aerotech kits aren’t great ones to wrap. The fins are molded with external fillets and tabs that snap into an internal locking mechanism. Any change of airframe diameter would prevent that system from working, and it works well.
On a hard hit, the fins will pop out of the lock for easy repair, if you’ve used CA for assembly as directed. Epoxy construction or additional external fillets can make repair more problematic. I’m betting you’ll like the thought put into that kit.
lr64
Well-Known Member
Looks like I messed up while editing the message. Try deleting "If you make a few".
Generally, a fabric weight is for just the fabric, not after adding the epoxy.
