Scratch Build: Waverider Level 1

[Orion14ed]

Here we go! I am extremely excited to start this build. First lets get an overview.

This is too be my certification vehicle for my Jr. Level 1. That is, if all goes to plan. It is designed to function as a mid-powered rocket, a very low performance one at that, and is expected to take a baby H at max after a flight with a similar impulse G. If there is any doubt in the build, I will set it down, get some advise, or stop it all together until I have the necessarily skills and knowledge to complete the task. That said, I feel confident going in, and am not worried about what I will be doing. Nothing that I have not done will be done in this build.

Waverider is a 4 fin rocket 3" in diameter. The rocket will use a 29mm motor mount, with an Estes retainer. Flights by others have shown this retainer to be fine for mid-high powered motors. The rocket's BT is 34" in length, and will use a LOC Nosecone. 2 rail buttons will be used on the rocket. A coupler is used as a separation point, and allows for a payload section to be added to add weights to stabilize the rocket. The fins will be 1/4" thick. A 36" chute is deployed at apogee for recovery. I will be using a 8.5' elastic for the shock cord, this can be changed, but since it is not going to be that heavy, I feel is should be fine...

Part list:
29mm Motor Tube
Rail Buttons
Mounting Assembly
Parachute
Coupler
Chute Protector
3" Tubing
Nose Cone
Shock Cord
2 Sets of Centering rings.
Bulkhead

Here is the OpenRocket file, with some screen shots of what is planned.
View attachment Waverider.ork



This is not an overly complicated build, which is why I hope to build it well, and well enough to certify with. Epoxy will be used to get the fins in place, with Tite-Bond for the rest of the build. This is designed to be a MPR rocket, if all goes well, I hope to push it to a small HPR motor. I am posting it in this section because I plan on using HPR build strategies, and would love some advise. I am starting work on the fins next week, and will be ordering the parts soon after. I will be taking my time, and hope to have this launch for my certification sometime before August.

Any advise would be great!

 

[DizWolf]

Looks pretty solid. The only changes I'd make would be 3/16" fins. I'd also skip the elastic and use an eye bolt in the top CR, a short bit of kevlar, and 8-12 foot of nylon. You'd still be at a good weight with F50's and up. It's not that I think the elastic will break, but it leads to tangles, and sometimes wild recovery twisting and springing. The smoother it's coming down, the less likely it is to damage on landing.

 

[Orion14ed]

Thanks for the advise! The elastic is just a placeholder for now... I need some for some other builds and since it is readily available, I figured it would be fine. Elastic is also a bit more forgiving when it comes to zippering... Rex on the forum helped me with some of the fine details. The 3rd centering ring will have the eyebolt mounted to a quick link. This will let me (I hope.) be able to switch out what shock cord I want. Since it is 3", I should be able to get my hand down there and switch things out. I also plan on using a quick link on the bulkplate as well, and attaching the chute and cord to that. This is all interchangable, so if when it is completed it is too heavy, I can switch everything out. I hope at least. The fins I want to be overly thick in case of hard landing. I may also launch on dry ground that is baked and hard. 1/4th Plywood should take the brunt of a less than optimal impact okay. (Bigger fins also results in a lower flight... I don't want anything over 2,000 for the certification flight.)

I plan on cutting the fins next week. To cut the slots for them, I will mark the spots, put some tape down, and run a straight edge next to the tape, and use a razor to cut them. The fins will be secured with 5 min epoxy originally (I know... nooby). Titebond wood glue will be used to make external fillets, along with internal fillets. I plan on getting some wooden dowels, and using them to help get the internal fillets to bond stronger. Fillets will be placed in 6 places on every fin. The rail buttons are not going to be difficult to put on. A bit of clay will be put behind each of the buttons to hold them in place.

 

[Handeman]

This looks like it will be a good rocket for all around use. My questions is, what rocket are you going to fly H & I motors in when you get your Jr L1?

My advice would be, if you already have a large MPR or two that can fly baby H motors, don't build another. Build something that is really a L1 rocket to cert on. Something with a 38mm MMT that will fly to a "good" altitude for your normal launch site on large H and baby I motors. On windy days you can stick with the baby H and keep it low, but on those rare perfect "no wind" days you can let it rip with a huge I motor. You will find that when you get your L1, you will have a much larger range of power to work with then MPR offers. The 120Ns difference between small F & large G motors isn't much when you look at the 480Ns difference between baby H and large I motors. It is also harder to build something that works well for the whole range of motors. If you try to include MPR in the performance envelope, you expand that envelope a lot and make it hard to get reasonable performance through the whole range.

 

[Orion14ed]

This looks like it will be a good rocket for all around use. My questions is, what rocket are you going to fly H & I motors in when you get your Jr L1?

My advice would be, if you already have a large MPR or two that can fly baby H motors, don't build another. Build something that is really a L1 rocket to cert on. Something with a 38mm MMT that will fly to a "good" altitude for your normal launch site on large H and baby I motors. On windy days you can stick with the baby H and keep it low, but on those rare perfect "no wind" days you can let it rip with a huge I motor. You will find that when you get your L1, you will have a much larger range of power to work with then MPR offers. The 120Ns difference between small F & large G motors isn't much when you look at the 480Ns difference between baby H and large I motors. It is also harder to build something that works well for the whole range of motors. If you try to include MPR in the performance envelope, you expand that envelope a lot and make it hard to get reasonable performance through the whole range.

You bring up some good points. I do have a MPR kit that could take a H, as well as another I could pick up and build over a weekend. The issue is, with these rockets the flight is going to be very fast and very high. I really want to avoid this. This is not designed at all to be a performance rocket, I could get much more performance out of a 38mm motor than in this rocket. I want to keep everything to a minimum. The idea behind this rocket is to be a rocket able to take a good size G, as well as a baby H. That is the design range I wanted. A F does not give me the power I want for a rocket of this nature. Sure, it will get it up just fine, but there is little margin for error on the recovery/ deployment on the recovery end. (I do not like low altitude flights for rockets designed to go much higher...)

I also have noticed the HUGE difference in thrust between H and G. I have been looking at thrust profiles, and seeing how rockets preform with different motors. This for example, sims at about 1,200 feet on a G80. An H 163 takes it to 1,400, but has a much higher initial thrust, and will result in higher loads in the flight, but does not change performance that considerably. This is what it was designed around.

 

[Handeman]

This looks like it will be a good rocket for all around use. My questions is, what rocket are you going to fly H & I motors in when you get your Jr L1?

My advice would be, if you already have a large MPR or two that can fly baby H motors, don't build another. Build something that is really a L1 rocket to cert on. Something with a 38mm MMT that will fly to a "good" altitude for your normal launch site on large H and baby I motors. On windy days you can stick with the baby H and keep it low, but on those rare perfect "no wind" days you can let it rip with a huge I motor. You will find that when you get your L1, you will have a much larger range of power to work with then MPR offers. The 120Ns difference between small F & large G motors isn't much when you look at the 480Ns difference between baby H and large I motors. It is also harder to build something that works well for the whole range of motors. If you try to include MPR in the performance envelope, you expand that envelope a lot and make it hard to get reasonable performance through the whole range.

You bring up some good points. I do have a MPR kit that could take a H, as well as another I could pick up and build over a weekend. The issue is, with these rockets the flight is going to be very fast and very high. I really want to avoid this. This is not designed at all to be a performance rocket, I could get much more performance out of a 38mm motor than in this rocket. I want to keep everything to a minimum. The idea behind this rocket is to be a rocket able to take a good size G, as well as a baby H. That is the design range I wanted. A F does not give me the power I want for a rocket of this nature. Sure, it will get it up just fine, but there is little margin for error on the recovery/ deployment on the recovery end. (I do not like low altitude flights for rockets designed to go much higher...)

I also have noticed the HUGE difference in thrust between H and G. I have been looking at thrust profiles, and seeing how rockets preform with different motors. This for example, sims at about 1,200 feet on a G80. An H 163 takes it to 1,400, but has a much higher initial thrust, and will result in higher loads in the flight, but does not change performance that considerably. This is what it was designed around.

I guess that's my question. If you have two rockets that can fly on G and H motors already, why build another? Why build a G/H rocket that can barely fly on G motors to keep the H lower but gets too high on large H motors?. Why not build something that will fly <1000 ft on a baby H and >3000 on a large I? 4" diameter at about 3.5 lbs should give you plenty of options in the H & I range without being too high or too low. Low flights with small H on windy days and higher flights on large I motors when it's a good flying day. If you want more range in altitude, go with a 3" diameter at 4 lbs. <1000 on a baby H and >4000 on a max I.

My L1 rocket was great for H & I motors. It was a scratch built 2.25" OD from mailing tubes, dual deploy, 3.5 lbs, and 38mm MMT. It would barely reach 1000 ft on small H motors, but would top 4000 ft on large I motors. Actually it got 6,810 ft on a J350W after I got my L2. It was the best L1 rocket I had because it flow a nice range of altitudes on the full range of L1 motors.

 

[DizWolf]

I went this route with my L1 rocket. 2.6" bluetube, about 40 ounces. About 400' on an F50T, 700-1000 on the larger G's, a little over 1200 for my cert flight on an H133BS. I200W should put it to 2300'.

F50T to I200W is suitably versatile for me. (And 2 grain-6XL CTI motors)

 

[Orion14ed]

Just a quick update here...

Just ordered the parts from LOC. Will be cutting out the fins along with cutting the BT soon after I receive the parts.

 

[rocketgeek101]

Nice design! I'll be following.

 

[Orion14ed]

So after going shopping for some food, I come home to a nice box from LOC. Great shipping speed. (I am really close to where it originated... bonus.)

Here is a picture of all of the parts. I am in love with the blue chute. Nice and big, my cat seems to love it. After a quick look over of the parts, everything fits nicely except for the centering rings. All but 1 (I purchased 4) are loose enough in the BT to just slide down. I am a bit worried this may be an issue, and am wondering how to go about it.



First thing is first, I have to mark the BT. I printed out the fin guide from OR and taped it onto the BT. I then used my ruler to make 4 straight lines. At parts they may seem a bit off, but that is because the thickness of my pencil seemed to change. It should not be a problem when cutting the slots, because the 4" that do require the line for a guide, are all straight as can be.



After those were marked, I measured the distance between the tab, and the back of the fin. This turned out to be around 1 1/8". I then marked this on a piece of paper, and marked a line across the BT. The line turned out good. It has a margin of error of about maybe 1/16". Again, this is not too much of an issue, as I can always make the tabs longer if needed.



The next line was the end of the tab from the front of it. This measures 4". I used the same system as before, and came out with a nice line. The distance is well within my personal margin of error, at most the measurement is just a slight "hair" above 4. So far, all the lines are well within my personal error margin. Even if the lines are off by a bit, they each only need to be used for 1/4th of an inch.



I only need to mark 4 more lines. (Only?) These lines will show the thickness of the fins. I then will begin to cut out the slots. Again, I am not concerned with the fin slots. I am actually very very pleased with the results so far.

In my awe of all of these parts, I realized the the bulk plate would fit inside the coupler. For some reason this had not clicked before. The plate would not fit into the coupler, so I sanded both of the parts down. I then epoxied the parts of the plate together, and was overall happy. Don't ask how I managed to get a buildup of crystals on the eyebolt. (I really just grabbed all the epoxy I had mixed, and threw it onto the bolt.) The bolt is going no-where, and it is time to connect the coupler and the plate. I slid the plate into the coupler, and flooded the inside with some tite-bond. The glue
evened out, and is drying now.



This build is coming along great so far. Tomorrow I hope to finish marking up the BT. I can't start to build the MT until I cut out the slots to see where everything fits. I will cut the BT along with the fins sometime this week.

The shock cord seems to be a bit small in thickness, I will do some playing around with it to see if I trust its strength.

Thanks in advance for any help!

 

[Orion14ed]

Today I managed to finish marking the body tube for the fin slots. Each slot is 4 inches long, as well as .25 inches thick. I made the lines slightly smaller than than the .25 to allow for me to trim down if the fin does not fit exactly. I still will do some final corrections if I see fit, but all is looking good for the fin slots.

I also did some shopping today. I picked up some nuts for the rail buttons, as well as some wood screws for the NC.

The bulk-plate has also finished drying.



I also found a nice bit to fit the size of the eye-bolt for the forward ring.I then found some washers that would fit, and will be epoxying the parts together tomorrow.



I also tried to get some swivels from the local fishing shop. They all are too small. Where would you recommend I check for some, or what sites can I trust for them? (Links?)

 

[terryg]

https://shop.locprecision.com/category.sc?categoryId=22


https://www.giantleaprocketry.com/products/components_recovery.aspx#D-Rings

 

[Orion14ed]

I woke up today and figured it would a good day to get the slots cut.

I first used some painters' tape to mark where I was to cut, and measured to make sure the length/width was what wanted.



I then cut away. So far I have 3 of the four slots cut, and am overall pleased.

Fin slots one and three turned out perfect. (In my standards.) Number two however, turned out a bit wide when it was finished. All 3 slots still tightly fit a piece of 1/4" plywood nice and tight, so I am not concerned about it being unsafe, but I will feel more comfortable when I fill this slot. It should be fixed when I do the external fillet, as well as the internal.

When I cut out the slots, I also had my razor run off and cut a bit outside of the range I was looking for. I took some wood glue and am filling the holes with it. I will be getting some bondo putty to fill the spirals soon.



And the wide slot. I should be able to fix this up when I do fillets.


Again, it still fits the thickness nice and tight, so I have no concerns about it.

Now that the slots are almost finished, I can start to work on the Motor Mount!


EDIT: All 4 slots are cut. 4th one is the best yet.

 

[Orion14ed]

https://shop.locprecision.com/category.sc?categoryId=22


https://www.giantleaprocketry.com/products/components_recovery.aspx#D-Rings

Thanks! I should have ordered this along with the parts.... DOH!

 

[Handeman]

Today I managed to finish marking the body tube for the fin slots. Each slot is 4 inches long, as well as .25 inches thick. I made the lines slightly smaller than than the .25 to allow for me to trim down if the fin does not fit exactly. I still will do some final corrections if I see fit, but all is looking good for the fin slots.

I also did some shopping today. I picked up some nuts for the rail buttons, as well as some wood screws for the NC.

The bulk-plate has also finished drying.

View attachment 133935View attachment 133936View attachment 133937View attachment 133938View attachment 133939

I also found a nice bit to fit the size of the eye-bolt for the forward ring.I then found some washers that would fit, and will be epoxying the parts together tomorrow.

View attachment 133940View attachment 133941

I also tried to get some swivels from the local fishing shop. They all are too small. Where would you recommend I check for some, or what sites can I trust for them? (Links?)

Check the fit on that eyebolt. You may not need to use the quick link because once the CR and eyebolt are in the rocket, you may not be able to get the quick link attached or removed. You might have to glue the CR in with the quick link attached.

 

[Orion14ed]

Check the fit on that eyebolt. You may not need to use the quick link because once the CR and eyebolt are in the rocket, you may not be able to get the quick link attached or removed. You might have to glue the CR in with the quick link attached.

I was planning on that. The fit within the tube is too tight for my hand to get into and unscrew/screw it together. I have to order some tubular nylon, attach it, and then glue in the motor mount because once it is in, I can not change it.

I was thinking this type of nylon. I know it is nothing compared to kevlar, but should hold it together for a few flights. I have a nomex blanket that I can get way down the tube to protect the cord and the chute.

Thanks for reminding me though

I also went ahead an sanded the inside of the cuts just to clean them up. Sanded the outside as well just to start to rough it up for fin attachment. I used 120, and will use 60 grit when I apply the fillets. Fillets will be done with tite-bond.

 

[Orion14ed]

One of the major things that separates any scratch-build from a kit is the fact that you have to do your own measurements. One example of this is the centering rings. The placement of the rings is critical to holding the motor, and securing the fins in place.

The goal is to have the forward ring contain an eye bolt, that is quick-linked to some tubular nylon. Some kits do not use a middle ring, however, I will be using one. The main reason is to be able to have an extra surface for the fin tabs to bond to. This ring will have all 4 fins touch it. The final ring will be placed in after all of the internal fillets have been done.

The only issue with finding the location of the rings is the fact that Open Rocket does not have a feature that will tell you the position based on the position of the motor mount tube. I had to do some playing with the file, because I want the MMT to be recessed about 1/4th of an inch. This will allow for the retainer to poke out of the BT. It will create less drag this way.

To find the exact location of the rings, I shortened the BT all the way to the forward end of the MMT. I then selected "from top of parent component" for the rings, to find the locations.

\

With the 10" MMT, 1/4" recessed, Open Rocket gives me these measurements from the forward end of the tube.

Forward ring: 1/2" from the forward end.
Middle ring: 4.75" from the forward end.
Aft ring: ~9" from the forward end.

You may notice that the middle ring does not back onto the tap. The reason is that I want to stick with simple lengths to measure. When I mount the Motor Mount, I will back this ring to where all of the tabs begin. This will move the whole tube about 1/4" back.

I would much rather have too much motor tube to place the retainer on, than not enough and end up having to go homemade.

I also have gone ahead and thickened the middle centering ring. I did this by taking masking tape, wrapping it around the ring, then using some wood-glue to harden it, and sanding it down in layers. I have a nice tight ring. The aft ring I want to be a nice slide into place with no complications, for that reason I will not change the other lose ring, and leave it be.



The plan is to go and cut the fins/tubes Saturday, if that will stick, I don't know. If it does though, this build will be on a good pace to be done by the end of the month, and ready to fly the next.

 

[Orion14ed]

You thought I was out of the game? No, just waiting on some things.

Today I ordered a few things from Amazon, these include:

1" Nylon Webbing- An inch wide, with a tensile strength of 4,200 Ilbs, this should get the job done well and should not zipper too easy.

#7 Ball Bearing Swivel- A size bigger than that sold from LOC, as well as 250 Ilb tested.

808 Keychain Camera- A long time coming, a nice camera to use on my rockets. Already have a 4gig microSD card to use in it.

All of these items will be here in due time.

I also am going to try to cut the fins tomorrow. The OpenRocket design was printed out, and cut out. Will be using 1/4th plywood.

I am going to cut the MMT and BT as well.

After all of the cutting is done, I should be making good progress. Any words of advise are much appreciated :3

 

[Handeman]

You thought I was out of the game? No, just waiting on some things.

Today I ordered a few things from Amazon, these include:

1" Nylon Webbing- An inch wide, with a tensile strength of 4,200 Ilbs, this should get the job done well and should not zipper too easy.

#7 Ball Bearing Swivel- A size bigger than that sold from LOC, as well as 250 Ilb tested.

808 Keychain Camera- A long time coming, a nice camera to use on my rockets. Already have a 4gig microSD card to use in it.

All of these items will be here in due time.

I also am going to try to cut the fins tomorrow. The OpenRocket design was printed out, and cut out. Will be using 1/4th plywood.

I am going to cut the MMT and BT as well.

After all of the cutting is done, I should be making good progress. Any words of advise are much appreciated :3

I think the 1" webbing is way over kill for this sized rocket, but if you have the room and don't mind the extra weight,.... 3/8 tubular nylon, or 1/8" tubular Kevlar would work just fine.

Be careful with the 808 keychain camera. If you over charge them, they tend to burn out and stop working. I've got one that will only hold enough charge to run for 2 - 3 minutes.

 

[Orion14ed]

I think the 1" webbing is way over kill for this sized rocket, but if you have the room and don't mind the extra weight,.... 3/8 tubular nylon, or 1/8" tubular Kevlar would work just fine.

Be careful with the 808 keychain camera. If you over charge them, they tend to burn out and stop working. I've got one that will only hold enough charge to run for 2 - 3 minutes.

Yeah, I am well aware that it is way overkill. The extra weight I do not mind at all. Mainly because of the thrust to weight ratio. It is through the roof for any of the motors I want to use. Since the motors only burn for 1 - 2 seconds, it will be okay with the extra weight. I plan on overbuilding it. Not too much, but a bit more than the average rocket because I want to cert with it.

Even a 3 pound rocket, will have an well over 5 to 1 thrust to weight ratio with a H133. It should not pass 2 with how I plan to build it. If it comes to it, I can shove a H163 in it.

 

[Orion14ed]

Today I got the stuff I received from Amazon.

The keychain camera works fine, video looks as nice as you would expect it to work for the price. The swivel fits the chute fine, but not my quicklink. Will need to get creative with how it all connects. The nylon looks nice and strong, I plan on sewing it together to connect to both of the quicklinks.



While I was waiting for my package, I got some wood filler. I started to fill the spirals in the BT. It may take a few coats to fill the spirals completely, but the filler I selected works well for some other projects as well.



I keep saying everything will be cut soon, and honestly I thought it would be done by now. Life keeps getting in the way. I will try again after this holiday weekend.

 

[Orion14ed]

Well today, I spent 2 hours at a carpenter's house cutting the fins. I had a ton of fun, and I was the one who made the cuts, he showed me what to do. I must say they are all about as good as fins can get.

So, now that we have all of the components, here is a "kit" picture :3



As you can see, we cut out two extra fins just for backup.

I also was able to cut a 7" payload section, and 1" off of the bottom of the NC.

The motor mount tube was also cut and measures 8"

I did not want to do much today, as it is 90 degrees outside and I have orders from my coach to rest for the remainder of my playoff, however I did manage to glue the first ring onto the MMT.

I first marked a line, and slid the ring on, and applied a ring of tite-bond around fore end of the ring.



And just some more pictures...



Next up, the middle ring, the fins, and the finishing of this puppy

 

[Handeman]

W
I did not want to do much today, as it is 90 degrees outside and I have orders from my coach to rest for the remainder of my playoff, however I did manage to glue the first ring onto the MMT.

I first marked a line, and slid the ring on, and applied a ring of tite-bond around fore end of the ring.

View attachment 138446

If possible, turn that eyebolt 90º or you may never be able to get a quick link on it once its in the BT. It may also interfere with the motor once it's turned. That is a good reason for a smaller eyebolt or longer MMT.

 

[Orion14ed]

I have a plan for getting everything connected, it is not going to be easy, but is possible. I have to get creative with getting the nylon through the mmt and place the quicklink in such a way that will let it go upright.

Also, my cat knocked down the motor mount down as the first ring was drying. I quickly cleaned everything up, and decided to take a different approach. I used some epoxy to glue the mount in originally, then used titebond around the ring.

I will get pictures later, I have the semis today.

 

[Orion14ed]

This thread died along with my willingness to build. About a month and a half ago, I really started to focus on school. I wanted to test out of a few subjects, and that meant large amounts of studying. All of my free time went into that endeavor.

When I was not working on my math and science, I had my summer job, which I must say was one of the most fun things ever for me. I actually enjoyed working because I was with all my friends. It taught me some respect, discipline, and some other things that can be applied to rocketry as well.

None the less, I tested out of Algebra 1, Physical Science, and ended up with the majority of my classes being a grade level higher. School is going to be challenging this year, and I am ready

The same thing applies to Waverider, she is far from perfect, far, far from perfect. When I looked at the rocket in the state it was in my last post, I really questioned if I could do it. I mean, look at the slots, they are terrible, look at the design, it is too big, and bulky. I looked at all options, and decided to stick with my gut. I would not have got myself into this situation to begin with if I could not handle it.

First order of business was the ever simple motor mount. It was not a problem for me in any other build. This build, however, it gave me much strife. For some reason, I could not get the rings on straight. I had to try a few times with each ring. This made me question if I would deal with the frustrations of things not going my way, and again, after I had finished the mount, I took a break.

I came back to glue the mount in, I used some Titebond to secure the middle ring in place. After 2 days of drying, I flooded the area forward of the forward ring, and let it sit. A week later, I was ready to do the task that scared me the most; the fins.

For me, fins had always been a problem. My eyes are fine at noticing details, such as that of misalignment. I never could settle with the placement of the fins, and therefore, would often move them when it was not needed, resulting in a less than optimal alignment.

I also had another challenge; I was going to use 5 min epoxy. Today, I was worried, 5 mins is not enough time for me to decide what I would get for lunch, much less than making the precise alignment of rocket fins. All I could think of was my rocket rolling at rapid speeds, and crashing into the ground after a mistake in alignment.

I took the epoxy for each fin, placed it carefully in the slot, and just let it sit. I found this way simple for fast setting epoxy. Set the fin in with ample epoxy, almost that it will make small fillets. Then, get it in the general position, I did this for 2-3 mins. About a few mins before it sets, I begin to get real keen with the detail, I make sure it looks straight from both ends, then, wait, double check, and before I know it, it is dry. Just before it is unmovable, it is in a state where it is held there enough to hold its own position, but also to be manipulated. This helps for people like me, who free hand the whole process.

The outcome, is satisfying, here are some pictures.



The next steps include:
Finishing the cargo bay.
Fillets.
Design changes.


Tomorrow I will explain the design changes, and how I am going to deal with the apparent weight issue. I can say right now, there is no way this will qualify was a mid powered rocket.

 

[Orion14ed]

Since last night I have done some serious work into ensuring large motor casing will fit into the rocket. Currently, I am getting about 450 grams - 907 grams. I am using a typical scale, which is notorious for being inaccurate anyway.

To make sure that a 4G case will fit, which is what I will need at the very least to get this rocket off the ground, I had to take out the nylon webbing. It was blocking the motor tube, and would not allow for higher class cases to be put in. The quicklink, however, is suborn as anything. I spent about 2 hours tugging, sanding, and plain out pulling, and it is still in there. The good thing is, that the link itself can be placed in such a position as that it will not move, and will stay out of the way of the case. I used duck-tape for a temporary solution. This may work in the long run, because after all this link will not have anything attached to it. That leads me to the changes.

First off, since this rocket is going to be too heavy to launch as a mid-powered rocket, I have adopted the philosophy of "go big, or go home." With this in mind, I plan on extending the payload bay, a good 2 - 3 feet. I am going to need extra weight near the forward end, much more than I originally anticipated. To use as a cord, I plan on getting some kevlar. It needs to be thin, and will wrap around only the eyebolt, this will allow for the quicklink to be non-movable, and the cord to be secured strongly. The kevlar will extend the lenth of the aft end of the rocket, and then be connected to some nylon.

Since the gluing of the fins went great, I woke up and used my time to start to fill the gaps left from the free-handed slot cutting. I needed something that would dry fast, but not run, for it only need to fit in a small area. I did not want to compromise the bonding of the wood-glue fillets I am to do, so I used a small amount of 5 min epoxy. I set it in the holes, and proceeded to wipe away excess, until all that was left was the epoxy filling the holes. This will act as a wall to the fin, as well as bonding it in a way that typical slots would not do. I will sand down any excess epoxy to a point where it is only inside of the holes.

Here is the result, I need more epoxy, so I will be working on fillets next time. Once the aft end of the rocket is finished, I will see the total weight, and take into account how I wish to proceed with the design.

If any of you have a clever way to get a quicklink out, tell me. I have already used my sister's hand, and it clear that it is perpetually stuck down there unless it breaks. It should not cause any problems, except for adding some weight.

Pictures:

 

[Orion14ed]

After roughing up the root edge of the 2 fins who have had the holes filled, I started the fillets.

I used some tape, and measured what I wanted to be a half inch fillet. I applied the glue, and spent a half hour making sure it the glue didn't drip off of the root edge. I removed the tape, and a straight line was what was left.

With one fillet finished, it seems too small for my liking. The strength of the fillet isn't directly proportional to the size, but at a certain point, the size does matter. I tried to make the next one larger, still the shrinking of wood glue is causing me some concern, do these look proper for this sized rocket?



I still have yet to epoxy the holes with the other fins, as well as do internal fillets.

 

[Aksrockets]

After roughing up the root edge of the 2 fins who have had the holes filled, I started the fillets.

I used some tape, and measured what I wanted to be a half inch fillet. I applied the glue, and spent a half hour making sure it the glue didn't drip off of the root edge. I removed the tape, and a straight line was what was left.

With one fillet finished, it seems too small for my liking. The strength of the fillet isn't directly proportional to the size, but at a certain point, the size does matter. I tried to make the next one larger, still the shrinking of wood glue is causing me some concern, do these look proper for this sized rocket?

View attachment 147385View attachment 147386View attachment 147387View attachment 147388

I still have yet to epoxy the holes with the other fins, as well as do internal fillets.

Those fins won't ever come off, but wood glue is not the best fillet adhesive. Like you observed, it tends to shrink and form holes that'll really show up in your paint job. I'd reccomend an epoxy for fillets.

Alex

 

[rocketgeek101]

Those fins won't ever come off, but wood glue is not the best fillet adhesive. Like you observed, it tends to shrink and form holes that'll really show up in your paint job. I'd reccomend an epoxy for fillets.

Alex

To add to this, done right, regular hobby epoxy can produce very nice fillets. If your set on not using epoxy for the fillets, you could try Tightbond modelling and trim glue. I've never used it, but have heard it works pretty well. A glue that I like to use for fillets on LPR rockets (but I would imagine it would work on HPR as well) is Weldbond. It's like a white/wood glue that sticks to many things besides wood/paper. It shrinks a bit, but not nearly as much as regular wood glue.

-S

 

[Orion14ed]

Those fins won't ever come off, but wood glue is not the best fillet adhesive. Like you observed, it tends to shrink and form holes that'll really show up in your paint job. I'd reccomend an epoxy for fillets.

Alex

Thank you!

I would use epoxy, but all outlets here only have the 5 min variant. I assume it can be used for this application, but since it was a paper to wood bond, I was certain wood glue would work.

Is it safe to use 5 min epoxy on fillets? I would think the low cure time would mean less "grip" for the fillet.

@rockgeek

I must have forgot to specify, I use exclusively tite-bond. Never had a fillet fail with it. It is quite nice, and holds it shape after about an hour sitting, so you can work on more parts than just one.