MADCOW 4" FRENZY CARDBOARD ROCKET... A BUILD THREAD #1

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TMJ

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As with 'any' new project, such as this, the first step is to carefully inspect all of the parts, dry fit everything... then start dreaming about a fantastic paint job and all of the "Ooooh's and Ahhhh's" that will soon come from family, friends and flight observers. This is where the build begins...;

"All parts are there and they all fit together extremely well!" My quality control inspector has thoroughly checked everything and has finally given me two paws up, with a tail wag!.. I can now start dreaming about the finished product and get down to the business of this HPR Level 1 build!

Next up... I will begin with the motor mount assembly, improvements, modifications, etc.., STAY TUNED!

Frenzy Dry Fit.jpg
 
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o1d_dude

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I did the same thing with my Frenzy.

It's currently at the fin fillet stage and I hope to have it ready to fly when Rocket Launch Season begins in the late fall or early winter. :y:
 

TMJ

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Thanks to many fine folks on this forum, a couple of books about HPR, and the 'University of YouTube'... I've finally gathered enough information to feel confident in starting my first high power build. Not everything that I do will be as per the kit instructions. I typically approach 'instructions' as a basic guideline, to be used for reference only, then I proceed to figure out better ways to get things done while also hoping to improve upon the finished results. I usually spend more time 'thinking things out', examining multiple approaches to doing things and trying to foresee pitfalls and/or flaws in my logic than I actually spend building. This project is no different! Should any of you folks find flaws in my way of thinking, my methods, etc., PLEASE chime in and give me your 'two cents worth'! I welcome ALL advice and suggestions! I'm sure that there are still MANY things that I have not considered, at this point. Things that I do not yet know to expect that could possibly bite me later on down the road. "Enough 'blurbage'; Here we go!"

***

I wasn't real happy with the single 'open' eyebolt that came with my kit, for two reasons. 1) A hard deployment would put a lot of stress on one small area of the forward centering ring which could possibly cause the plywood ring to crack/fail. There's also the possibility that the open ring could actually open up and cause a failure. I chucked the eyebolt and replaced it with 'two' 'U-Bolts', with backing plates, thus creating a much larger footprint to distribute any stress loads over a much greater area. Not trusting standard nuts/washers to remain secure... I used lock washers 'AND' nylon lock nuts on the bottom side of the forward centering ring and just a nut and washer on top. The threads are all coated with super glue and once I am happy/ready to make the centering rings disappear down inside the booster section, the hardware will be encapsulated in epoxy.

This is the dry fitted motor mount assembly;
MM Dry Fit~2.jpg MM Dry Fit~1.jpg 54mm Motor Mount.jpg

Forward Centering Ring;
The backplates for the u-bolts were a bit too large, so I had to grind them to fit the outside of the motor tube and also fit inside of the main body. No biggie. "Dremel!"
The u-bolts are 1/4" diameter. That's probably overkill, but Home Depot didn't have anything smaller. "There goes a few feet in altitude!" LOL, but hey. This is for certification. I don't mind 'low and slow'!
Forward Centering Ring~Top.jpgForward Centering Ring~Bottom Side.jpg

Aft Centering Ring;
I installed 6-32 blind nuts for positive motor retention. That's probably overkill, too, but once again. #6 was the smallest that Home Depot carried.
That extra small hole you see is simply a vent, for equilibrium, to prevent the sealed portion of this rocket from pressurizing on its way up.
Aft Centering Ring Bottom~Outside.jpgAft Centering Ring Top~Inside.jpg

The motor mount tube, itself, has been thoroughly sanded to remove that slick skin and make for a better epoxy joint when I glue everything up. I've also coated both ends, inside and out, with super glue to strengthen the edges/ends of the tube.

My current thought of assembly is to initially leave 'both' centering rings loose on the motor tube, secured by tape only. Insert assembly, to its proper location in the booster, then epoxy the root of the fins to the motor mount tube. Once the epoxy has cured, remove one centering ring at a time and add epoxy/fiberglass cloth reinforcement to the fins, motor tube and inside of the booster tube. This should be 'great' insurance in keeping the fins on during launch/touchdown. Leaving both centering rings loose will allow me to more easily reach both the upper and the lower fins, for reinforcement, on this split fin design. "There goes 'ANOTHER' few feet in altitude! :smile: Once everything is cured, I'll epoxy the two centering rings in place, add small decorative fillets to the outside joints of the fins/body tube and move on from there. Stay tuned for part three... Installing the motor mount!
 

DavidMcCann

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FG strips in the internal fillets is quite likely overkill. If you're doing it to learn technique, that's cool, but realize it's not needed and adds weight in a bad spot (aside from being a pain in the ass to boot). Wood glue on plywood fins has held up to the point the fins themselves snapped off leaving the glued part of the fin still attached.

This is from Ari's L3 project "Price of Admission" - https://www.rocketryforum.com/showt...t-Price-of-Admission-quot&p=502888#post502888

There's overkill, and there's hindering yourself without benefit. Finding the balance is the trick.
 

Buckeye

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There are several Frenzy build threads, including one by yours truly. I agree with David, extra building on this kit is not necessary. The Madcow instructions are pretty reasonable. The stock eyebolt and fins are plenty strong for this rocket - they are not going anywhere. My only concern was the CG, so I avoided adding extra weight to the ass end of this thing. After 4 years of flying the Frenzy, the only damage is to the cardboard body tubes here and there. If any fiberglassing is needed, the body tubes would be the extent of it.

I assume the Frenzy still comes with the 54mm motor mount. Since ~85% of 54mm motors are J and above, this is really a Level 2 rocket, in my book. Over-building this kit will not leave you many L1 motor options for a good flight, especially if it is windy.
 

Flyfalcons

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True but a 38-54 adapter comes in handy to open up a lot of options. My BBIII will be about the same size and weight and OR shows plenty of L1 38mm loads working fine. Agree on trying to keep it light and not totally overdoing everything on the build though.
 

DavidMcCann

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True but a 38-54 adapter comes in handy to open up a lot of options. My BBIII will be about the same size and weight and OR shows plenty of L1 38mm loads working fine. Agree on trying to keep it light and not totally overdoing everything on the build though.
38's will be fine sure, but that's the top end/high range of L1 offerings. Too much weight will thin the field of options even more.

Of course, you can always pop L2 motors in it after getting L1.
 

Buckeye

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Thanks to many fine folks on this forum, a couple of books about HPR, and the 'University of YouTube'... I've finally gathered enough information to feel confident in starting my first high power build.
All good, but throw in some simulations, also. At a minimum, run a bunch of motors through Thrustcurve to sort through your L1 options and expected performance.

I usually simulate the hell out of a rocket (OR, RASAero, RS) before I plop down a couple hundred bucks on a kit, motor, electronics, and accessories.
 

AfterBurners

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Mike's kits are awesome and they always fit really well. I have never had any issues whatsoever with his kits and the quality is outstanding!!!
 

Banzai88

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Speaking as a BAR starting my second year and studying for my L2 flight:

Take the 'horror stories' here about how terrible the basic hardware, basic ply, basic 'chutes, basic computers, basic glue, and how you must always have the largest motor hole possible in the threads here on TRF with a mountain of salt. It'll lead you to WAY overbuild, and not realize the altitude that you pay for each time you light a motor.

A nose heavy rocket, at worst, flys lower than it would otherwise. A tail heavy rocket, at worst, has the potential to fly once.

Usually to fix a tail heavy rocket, you have to make an overly nose heavy one, and then you start to encounter other problems.

Get familiar with Open Rocket. It's worth the learning curve, and will help you properly scope your rocketry expectations.
 
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AfterBurners

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Thanks to many fine folks on this forum, a couple of books about HPR, and the 'University of YouTube'... I've finally gathered enough information to feel confident in starting my first high power build. Not everything that I do will be as per the kit instructions. I typically approach 'instructions' as a basic guideline, to be used for reference only, then I proceed to figure out better ways to get things done while also hoping to improve upon the finished results. I usually spend more time 'thinking things out', examining multiple approaches to doing things and trying to foresee pitfalls and/or flaws in my logic than I actually spend building. This project is no different! Should any of you folks find flaws in my way of thinking, my methods, etc., PLEASE chime in and give me your 'two cents worth'! I welcome ALL advice and suggestions! I'm sure that there are still MANY things that I have not considered, at this point. Things that I do not yet know to expect that could possibly bite me later on down the road. "Enough 'blurbage'; Here we go!"

***

I wasn't real happy with the single 'open' eyebolt that came with my kit, for two reasons. 1) A hard deployment would put a lot of stress on one small area of the forward centering ring which could possibly cause the plywood ring to crack/fail. There's also the possibility that the open ring could actually open up and cause a failure. I chucked the eyebolt and replaced it with 'two' 'U-Bolts', with backing plates, thus creating a much larger footprint to distribute any stress loads over a much greater area. Not trusting standard nuts/washers to remain secure... I used lock washers 'AND' nylon lock nuts on the bottom side of the forward centering ring and just a nut and washer on top. The threads are all coated with super glue and once I am happy/ready to make the centering rings disappear down inside the booster section, the hardware will be encapsulated in epoxy.

This is the dry fitted motor mount assembly;
View attachment 295898 View attachment 295899 View attachment 295904

Forward Centering Ring;
The backplates for the u-bolts were a bit too large, so I had to grind them to fit the outside of the motor tube and also fit inside of the main body. No biggie. "Dremel!"
The u-bolts are 1/4" diameter. That's probably overkill, but Home Depot didn't have anything smaller. "There goes a few feet in altitude!" LOL, but hey. This is for certification. I don't mind 'low and slow'!
View attachment 295900View attachment 295901

Aft Centering Ring;
I installed 6-32 blind nuts for positive motor retention. That's probably overkill, too, but once again. #6 was the smallest that Home Depot carried.
That extra small hole you see is simply a vent, for equilibrium, to prevent the sealed portion of this rocket from pressurizing on its way up.
View attachment 295902View attachment 295903

The motor mount tube, itself, has been thoroughly sanded to remove that slick skin and make for a better epoxy joint when I glue everything up. I've also coated both ends, inside and out, with super glue to strengthen the edges/ends of the tube.

My current thought of assembly is to initially leave 'both' centering rings loose on the motor tube, secured by tape only. Insert assembly, to its proper location in the booster, then epoxy the root of the fins to the motor mount tube. Once the epoxy has cured, remove one centering ring at a time and add epoxy/fiberglass cloth reinforcement to the fins, motor tube and inside of the booster tube. This should be 'great' insurance in keeping the fins on during launch/touchdown. Leaving both centering rings loose will allow me to more easily reach both the upper and the lower fins, for reinforcement, on this split fin design. "There goes 'ANOTHER' few feet in altitude! :smile: Once everything is cured, I'll epoxy the two centering rings in place, add small decorative fillets to the outside joints of the fins/body tube and move on from there. Stay tuned for part three... Installing the motor mount!
Your methods make sense, but you are adding a lot of weight. I can see throwing away the open eye bolt, but why not just replace it with a close welded eye bolt you can buy off WM. My :2:
 

AfterBurners

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Take the 'horror stories' here about how terrible the basic hardware, basic ply, basic 'chutes, basic computers, basic glue, and how you must always have the largest motor hole possible in the threads here on TRF with a mountain of salt. It'll lead you to WAY overbuild, and not realize the altitude that you pay for each time you light a motor.

A nose heavy rocket, at worst, flys lower than it would otherwise. A tail heavy rocket, at worst, has the potential to fly once.

Usually to fix a tail heavy rocket, you have to make an overly nose heavy one, and then you start to encounter other problems.

Get familiar with Open Rocket. It's worth the learning curve, and will help you properly scope your rocketry expectations.
I agree well said. Every rocket I have built even high powered has been with wood glue aka Titebond II. I use wood glue on all wood and card board projects whether they are kits or scratch build. The other time that I would use epoxy is when I am gluing the motor mount assembly into fuselage. I've had wood glue lock up on me before and I don't want to go through that again. Heavy rockets = Bricks whereas properly built light weight, but strong rocket will go much higher and perform better. The only time you would really use epoxy is when you join two unlike materials or if you are building fiberglass or carbon fiber.If you were to use all that extra hardware, epoxy and whatever else, why not just buy a fiberglass rocket? I don't want to come across as an a$$ but I'm just saying I think once you build couple without all that extra stuff you will find out that hey it actually flies pretty good.:)
 
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TMJ

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Your methods make sense, but you are adding a lot of weight. I can see throwing away the open eye bolt, but why not just replace it with a close welded eye bolt you can buy off WM. My :2:
I could actually 'weld' the eyebolt closed, myself, but chose not to. I wanted to spread the load out over a greater area to reduce any localized stress from hard ejection charges, which may be possible. I'll be using shear pins and being a rookie who also manufactures his own black powder (burns faster than commercial)...??? Just playing it safe. Also, as for the added weight? Well, I'm not looking for blistering speeds up into the stratosphere. I'd like to keep things 'low & slow' for my certification flights. If I do things correctly, build heavy enough, and use the proper engine... I feel as though I can deploy my recovery system about the same time that my two ton rocket clears the rail. The hard ejection charge will snatch the rocket a few feet higher giving time for the chute to deploy at about twenty feet and land the rocket, safely, 6" from the launch pad! LOL, just kidding of course. I don't mind the added weight, not for 'this' rocket. I just want a successful certification... :wink:
 

AfterBurners

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I could actually 'weld' the eyebolt closed, myself, but chose not to. I wanted to spread the load out over a greater area to reduce any localized stress from hard ejection charges, which may be possible. I'll be using shear pins and being a rookie who also manufactures his own black powder (burns faster than commercial)...??? Just playing it safe. Also, as for the added weight? Well, I'm not looking for blistering speeds up into the stratosphere. I'd like to keep things 'low & slow' for my certification flights. If I do things correctly, build heavy enough, and use the proper engine... I feel as though I can deploy my recovery system about the same time that my two ton rocket clears the rail. The hard ejection charge will snatch the rocket a few feet higher giving time for the chute to deploy at about twenty feet and land the rocket, safely, 6" from the launch pad! LOL, just kidding of course. I don't mind the added weight, not for 'this' rocket. I just want a successful certification... :wink:
As they say there's more than one way to skin a cat
 

DavidMcCann

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strength is good..... but careful not to take a couple two ton chains and tie them together with dental floss.

Find your weak point in any chain, minimize it, and don't bother building the rest of the chain past it. I'll recommend commercial 4f powder once here and not go beyond that. But the larger point is any charge that would cause an issue with two 1/4" u bolts would have long since destroyed the actual tube its all riding in. Of course my L1 has a 29mm mount, and a 1/4" u bolt in it with half inch TK. live and learn ;)
 

TMJ

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strength is good..... but careful not to take a couple two ton chains and tie them together with dental floss.

Find your weak point in any chain, minimize it, and don't bother building the rest of the chain past it. I'll recommend commercial 4f powder once here and not go beyond that. But the larger point is any charge that would cause an issue with two 1/4" u bolts would have long since destroyed the actual tube its all riding in. Of course my L1 has a 29mm mount, and a 1/4" u bolt in it with half inch TK. live and learn ;)
The only reason that I used 1/4" u-bolts is because Home depot didn't have anything smaller. I'd have preferred #10's, maybe even #8's, but I didn't feel patient. Didn't want to order them and wait for the postman to deliver. I agree. Any charge that would damage two 1/4" u-bolts would be quite excessive. I wouldn't have a rocket, not with a charge 'that' strong. I'd have something worthy of a 4'th of July fireworks display! 4F powder is a bit hard to come by, here. 3F and 2F are readily available, but all come at a very high price. I'm a muzzleloader and got tired of the high price from Bass Pro, hazmat fees, minimum quantities to order, etc.. That's why I learned to make my own. 4F is only used for the flash pans in flintlocks. It burns very fast. It's also very susceptible to humidity. I found that 3F, sometimes even 2F works just as good, if not better in flintlock flashpans. I'm veering off onto a tangent... Back on track, now. I've learned to back off on my powder loads for muzzleloading. I'll need to do the same with HPR ejection charges. I'll simply need to test the loads, on the ground, and see what works best, via 'my' powder, before flight.
 

TMJ

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I had to change my strategy for inserting the motor mount with 'both' centering rings loose. When dry fitting everything, to see how it would work, it was just too far a reach to easily get to the forward set of fins for added reinforcement. "Lesson learned!" I've now epoxied the forward centering ring to the motor tube, as instructed by the manufacturer. I'll leave the aft centering ring loose, and go in from the rear to do any reinforcements. After a 24 hour cure, and some head scratching on the 'Y' harness attachment I'll be ready to proceed.

This is my progress, so far. I have put fillets on both sides of the forward centering ring. It's currently sitting in my ebay, just to keep it upright until the epoxy on the underside cures enough to not run.

I weighed all of the metal components that I have installed, via my modifications to the build. So far I'm only 1.6 ounces heavier than if I were to have used the hardware supplied. This weight includes the three 6-32 blind nuts and machine screws for motor retention. I'm happy with that. I was actually thinking it would have been 'more' weight than that!
FWD Centering Ring Epoxied and Curing.jpg

Now, while I wait for the epoxy to cure... what about the 'Y' harness? That's what I'm currently scratching my head about. Should I simply tie the 3/8" kevlar tube to the 'U'-bolts, use quick connects (more weight), or what? Is 3/8" kevlar 'overkill'? I'm open for all suggestions, here! :smile:
 

neond7

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I would seriously recommend a middle centering ring - the body can flex and crumple there on a hard landing. I know this from experience.

A single 1/4 u-bolt would have been fine - a single u-bolt was just fine for my 30 lb. level 3 project.

I currently have another one of these in a box to replace my retired Frenzy. Great flying kit, the CTI J410R was my favorite motor for it. I used a LOC Precision avionics bay for it.

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TMJ

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You could tie a slip knot?
I'm all for that! I was just wondering if good knots would be strong enough, for high power, or if there should be loops sewn into the harness/cord.
 

TMJ

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I would seriously recommend a middle centering ring - the body can flex and crumple there on a hard landing. I know this from experience.

A single 1/4 u-bolt would have been fine - a single u-bolt was just fine for my 30 lb. level 3 project.

I currently have another one of these in a box to replace my retired Frenzy. Great flying kit, the CTI J410R was my favorite motor for it. I used a LOC Precision avionics bay for it.

Subscribed!
About that 'middle' centering ring... you've caught my attention. Could you please 'elaborate' on the situation(s) that caused such a hard landing? Wouldn't a slightly larger main chute solve this problem? I'm all about structural integrity. I've no problem installing another centering ring if it would certainly be a 'plus' for longevity!!!
 

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My question, with the U bolts in the position you have them, will you have enough room to hook a quick link to them? I'm currently building the same kit, using stock components. During dry fitting, I had to make sure the included eyebolt was at an angle to the airframe and mmt, in order to be able to attach a quick link. The only modification I plan to make to mine, in the fin can, is to add some expanding foam, to aid in prevention of the body tube crumple that Jeff mentioned.
 

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Now that Jeff has broached the subject of an addional centering ring...

My Frenzy has centering rings at the ends of each fin tang to provide additonal support. A liitle counting reveals that I have three extra centering rings. The top centering ring sits on top of the forward fin tangs. Used injected internal fillets according to the Crazy Jim method. I will be using an Aeropac 54mm motor retainer...doesnt get much more secure than that.

The additional weight in the tail is offset by using a 1/2" kevlar Y-harness (no u-bolts and assorted hardware) and the fact that I have a Madcow removable alt-bay. Dual deploy puts a lot of the recovery train up in the foward compartment and the tracker goes up in the nose cone behind a bulkplate on a sled. Definitely not a Level 1 cert bird.

A lot of rocketeers fiberglass the fin can section but I chose not to go that route. Madcow sells a fiberglass Frenzy which involves a lot less work albeit at a greater weight penalty.
 

TMJ

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My question, with the U bolts in the position you have them, will you have enough room to hook a quick link to them? I'm currently building the same kit, using stock components. During dry fitting, I had to make sure the included eyebolt was at an angle to the airframe and mmt, in order to be able to attach a quick link. The only modification I plan to make to mine, in the fin can, is to add some expanding foam, to aid in prevention of the body tube crumple that Jeff mentioned.
Yes, plenty of room for a quick link, or 'two'. The 'U'-bolts actually extend about 5/8" of an inch of 'usable' I.D. dimensions beyond the top of the motor tube. I've actually put my hand down the tube and 'acted' like I was turning a connection to insure that it is feasible. A bit cramped, but totally doable, with 'my' hands!
 

TMJ

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Now that Jeff has broached the subject of an addional centering ring...

My Frenzy has centering rings at the ends of each fin tang to provide additonal support. A liitle counting reveals that I have three extra centering rings. The top centering ring sits on top of the forward fin tangs. Used injected internal fillets according to the Crazy Jim method. I will be using an Aeropac 54mm motor retainer...doesnt get much more secure than that.

The additional weight in the tail is offset by using a 1/2" kevlar Y-harness (no u-bolts and assorted hardware) and the fact that I have a Madcow removable alt-bay. Dual deploy puts a lot of the recovery train up in the foward compartment and the tracker goes up in the nose cone behind a bulkplate on a sled. Definitely not a Level 1 cert bird.

A lot of rocketeers fiberglass the fin can section but I chose not to go that route. Madcow sells a fiberglass Frenzy which involves a lot less work albeit at a greater weight penalty.
"Definitely not a level 1 cert bird?" I like that... "It makes for a 'better' challenge!" :wink: I too have the removable alt. bay. I'll also being doing dual deployment with redundant electronics and deployment systems. Sounds as though I am on the right track!!!
 

TMJ

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My question, with the U bolts in the position you have them, will you have enough room to hook a quick link to them? I'm currently building the same kit, using stock components. During dry fitting, I had to make sure the included eyebolt was at an angle to the airframe and mmt, in order to be able to attach a quick link. The only modification I plan to make to mine, in the fin can, is to add some expanding foam, to aid in prevention of the body tube crumple that Jeff mentioned.
"Expanding Foam"... Hmmm...??? I like it. I wonder how much weight that it would add? Maybe I'll open up my vent hole(s) in the aft centering ring, just in case that the finished weight/balance allows for the addition of some foam! :cool: Thank you!
 

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You're excited to be starting in rocketry. That's good. But don't let the awesome run away from you here.

"Definitely not a level 1 cert bird?" I like that... "It makes for a 'better' challenge!"
Nope, it makes for a rocket too heavy to safely fly on an L1 motor. If you don't have 5:1 thrust to weight, It's not going to be allowed to fly. Even at 5:1, wind may give you hell. The challenge on flying this rocket on an L1 motor is to keep it light. Challenges are good, but you can't challenge physics.

"Expanding Foam"... Hmmm...??? I like it. I wonder how much weight that it would add? Maybe I'll open up my vent hole(s) in the aft centering ring, just in case that the finished weight/balance allows for the addition of some foam! :cool: Thank you!
I'm in the camp that thinks foam is a terrible idea in any rocket. (its a small camp). In this rocket, it would be better to reduce weight, than add more in the ass end. Foaming the can will add weight in an already strong area...and increase the odds of crumpling the forward section.

No foam, no thru the wall fins, hit the ground going 450 MPH. fincan area was fine, rest.... not so much.
 
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thomas

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The rocket is weighting slightly above 2kg so with an I284 you get an thrust to weight ratio of over 10, 20 if you consider the thrust peak. If you are insane you could even go for an I600. So physics is not against a Level 1 Motor.
 
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