My Madcow Tomach (Money Burner)

Hello everybody.
This afternoon I picked up my Madcow Tomach from Bay Area Rocketry, so I figured I would start a build thread. (Although most of it will probably be me asking questions on how to do certain things). I will start this of by saying that this rocket will be a few firsts for me; first fiberglass rocket, first high power rocket, first dual deploy rocket, and if all goes right, my L1/L2 rocket.

My goal for this build is to have it done by April, so I can launch it at Snow Ranch before it shuts down for the season. I am planning on getting my L1 then, and then hopefully making it to Mudroc for my L2. For my L1, I am planning on using something like the I600 in the 38/720 case. (Go big or go home!) I know most people suggest a small H for the cert flight, but I figure if I use a small H, I will just want to launch it again right away on an I, so why not do it all at once. (I will have a tracker). For my L2, I am planning on a CTI L935, which sims to around 20k-22k feet.:eyepop: (Like I said above, go big or go home!).

Now that i have my goals stated, I will move onto my plans/questions.
1- Motor retention - I bought an Aeropack 54mm minimum diameter retainer, and I am planning on using three bolts through the body tube to hold it in place, instead of epoxy. I like the idea of being able to remove it if I need to. I have seen other builds do it this way, and it has worked for the. I am also thinking about porting the retainer, like the 38mm ones are. This will allow me to use motor ejection backup with the use of the Aerotech RAS system. Has anybody ported one before? (I tried searching)

2- Fins - I plan on using Aeropoxy es6209 for the the root edges, and then do the fillets with Proline 4500, since it it rated to higher temperatures. Does this sound good? I was also thinking of coating the leading edges of the fins in Proline, for both heat protection and looks. I thought about doing tip to tip, nut decided against it as most people say it is unnecessary on a 54mm minimum diameter rocket. If it would help, I have no problem trying it as long as I can find somebody close to help me.

3- Shear pins - I am planning on using three 2-56 nylon screws, since I have read that any less can cause binding.

4- Electronics - I am planning on using my Eggtimer TRS in this rocket for dual deploy. I am also looking into the Doghouse Rocketry charge wells with integrated terminals. Altimeter sled will be a 3d printed 54mm sled from Landru, along with a Mobius mount I will make removable.

5- Recovery - I plan on doing drogueless dual deploy. Is this good, or should I use a small drogue/streamer? For a main I plan on using my homemade 48" hemispherical chute, which should be plenty for a nice soft landing. I am going to use the tubular nylon that came with the kit to start, but plan on upgrading to a OneBadHawk tubular kevlar harness in the future.

6- Launching - I am planning on making a launch tower for this rocket using bicycle wheels as the base, like others have done. What would be a good height for the tower? I was planning on eight feet, because transporting it is no issue.

Now that I have the main questions out of the way, here are some random ones in no random order.
What is the best way to square the ends of the fiberglass tube? A table saw, hand file, something else?
Anybody have a name suggestion?
Anybody think I'm crazy?
Am I missing anything?

If you have gotten this far, I appreciate it. I am looking forward to having fun building and flying this rocket, am I am sure I this thread will get lots of more questions from me.
Cheers,
Kyle Rodrigues

(And since a build thread is worthless without pictures, here is one of my rocket after I washed the parts this evening, and also one of a CTI 54mm 6GXL case next to my size 12 shoe. It's huge!)

Hey Kyle - glad to see you're doing a build thread for this project! I definitely think we can put our heads together on our respective Tomach builds...

I like your motor choices - the L935 should really move! What type of tracker do you use?
I am planning on using 3 x 2-56 screws on my rocket as well (drogue and main). Yes less than that can cause binding, but just make sure that they will be strong enough to hold.
Correct - you don't need a drogue. I am going drogueless as well, I've flown WAY larger rockets this way before with no issues.
My rocket will have rail buttons, attached using weld nuts glued to the exterior of the airframe.

Did your kit come with uneven tube ends?
Oh yeah, I need to name mine too...

Good luck on the build! Hope to see you at an AeroPac launch this year.

For a tracker I am going to use the Eggtimer TRS, with the antenna mounted to the avbay bulkhead and extending into the main chute section. For black rock I may add a second tracker in the nose cone, but I'm not sure yet.

As for the uneven ends, a couple are off by maybe 1/16-1/8 and don't match up, which may not affect much, but I'm a bit of a perfectionist so it is bugging me.

And if you make it to Mudroc, wanna drag race?

Thanks for the input,
Kyle Rodrigues

rc dude said:

For a tracker I am going to use the Eggtimer TRS, with the antenna mounted to the avbay bulkhead and extending into the main chute section. For black rock I may add a second tracker in the nose cone, but I'm not sure yet.

As for the uneven ends, a couple are off by maybe 1/16-1/8 and don't match up, which may not affect much, but I'm a bit of a perfectionist so it is bugging me.

And if you make it to Mudroc, wanna drag race?

Thanks for the input,
Kyle Rodrigues

Click to expand...

Hello Kyle !

Great project with a lot of firsts . Keep it simple superior flier comes to mind.

Go electronics only and think through your not 54mm motor retention . Do a 'in view or see the event' flight to confirm electronics are working.

If you go TN then make a bit longer so you can cut off the charred ends on subsequent flights.. CJ would use 750lb kevlar up top for the smaller space .

Leaving the lugs off and strapping a camera to the rocket send a mixed message. Do a taped on camera flight for the in view flight where drag is not a concern .

TFish suggests an 'almost' Tip to Tip , bring out fabric to where the fin bevels start not the tip .. if your proline the bevels you could hide the lip of the fabric too. You can always cut a fillet size swatch of FG or CF and epoxy to the root edge fin joint and hide the reinforcement in the proline fillet.

You could add buttons, then remove when tower is up then drizzle in some epoxy to bury the holes.

Sim out with the K300 and the L265 also after its built and you have a flight in to tweak the sims - you may go mellow !

Keep us apraised of the project and post some pics !

Kenny

rc dude said:

For a tracker I am going to use the Eggtimer TRS, with the antenna mounted to the avbay bulkhead and extending into the main chute section. For black rock I may add a second tracker in the nose cone, but I'm not sure yet.

As for the uneven ends, a couple are off by maybe 1/16-1/8 and don't match up, which may not affect much, but I'm a bit of a perfectionist so it is bugging me.

And if you make it to Mudroc, wanna drag race?

Thanks for the input,
Kyle Rodrigues

Click to expand...

I thought the range of the Eggtimer was around 20K? Never flown one myself, but I have seen several occasions where the transmitter "loses GPS lock and never regains" - just saying...
And yes, redundants never hurt!

I won't be at Mudroc (weekend before NXRS), but am going to Aeronaut and maybe XPRS.
Also, I think I'm with Kenny on leaving out motor ejection and going all electronic for deployment. Much more reliable.

KenRico said:

Hello Kyle !

Great project with a lot of firsts . Keep it simple superior flier comes to mind.

Go electronics only and think through your not 54mm motor retention . Do a 'in view or see the event' flight to confirm electronics are working.

If you go TN then make a bit longer so you can cut off the charred ends on subsequent flights.. CJ would use 750lb kevlar up top for the smaller space .

Leaving the lugs off and strapping a camera to the rocket send a mixed message. Do a taped on camera flight for the in view flight where drag is not a concern .

TFish suggests an 'almost' Tip to Tip , bring out fabric to where the fin bevels start not the tip .. if your proline the bevels you could hide the lip of the fabric too. You can always cut a fillet size swatch of FG or CF and epoxy to the root edge fin joint and hide the reinforcement in the proline fillet.

You could add buttons, then remove when tower is up then drizzle in some epoxy to bury the holes.

Sim out with the K300 and the L265 also after its built and you have a flight in to tweak the sims - you may go mellow !

Keep us apraised of the project and post some pics !

Kenny

Click to expand...

I plan on maidening it on a full G motor, which will go around 1000ft, just to double check the deployment, then let it rip on the I600. For motor retention I was thinking of using a motor adapter down to 38mm, which will take care of the thrust ring and centering the motor, and using a plugged closure and an extension to use the internal retainer. Like this, where bright green is the adapter, and dark green is the extension.


Your idea for electronic only sounds good to me, and I will be sure to thoroughly test the electronics beforehand in another rocket, along with plenty of ground tests.

As for the camera, I was looking at Landru's mobius mount, so I can have threaded inserts inside the body tube, and be able to remove it when I am going for performance. Although tape might work as well.

Finally for the tip to tip, I was going to follow TFish's video on how to do it. I was just wondering if it would be worth the work.

I'll be sure to post more pics once I start building, I'm currently waiting for my Aeropoxy to arrive, and I need to start ordering some more parts.

AlnessW said:

I thought the range of the Eggtimer was around 20K? Never flown one myself, but I have seen several occasions where the transmitter "loses GPS lock and never regains" - just saying...
And yes, redundants never hurt!

I won't be at Mudroc (weekend before NXRS), but am going to Aeronaut and maybe XPRS.
Also, I think I'm with Kenny on leaving out motor ejection and going all electronic for deployment. Much more reliable.

Click to expand...

The range for the TRS is 30k, so I should be good in that regard. I also plan on having a separate tracker in the nose cone for flights above 12k-15k, just for redundancy.

I won't be able to make it to Aeronaut, as I'll be in Europe, but I'll see if I can make it to XPRS.

Cheers,
Kyle Rodrigues

rc dude said:

Finally for the tip to tip, I was going to follow TFish's video on how to do it. I was just wondering if it would be worth the work.


Cheers,
Kyle Rodrigues

Click to expand...

TFish's video is great and TFish is in the supreme expert category. Some key differences in his build from the Madcow Tomach. TFish used a much thinner fin. He discusses selectively building up his fins with tip to tip to get reinforcement at the base and middle of fin. I don't recall right off hand, but his final fin thickness was still pretty thin at its maximum thickness. The Tomach fins are 1/8 inch all through and are not bevelled. You will have to bevel. If you add tip to tip to the Madcow fins, they are going to be pretty thick, and the ttt will add weight. You might think about CJ's Space Cowboy surface mounted technique with good filets. I can dig up the link if necessary. With a full 1/8 inch fin root surface for mounting, tip to tip may not be necessary, at least for K300. Not sure if people have tested on L935. Good luck with your decisions and build.

4kids49 said:

TFish's video is great and TFish is in the supreme expert category. Some key differences in his build from the Madcow Tomach. TFish used a much thinner fin. He discusses selectively building up his fins with tip to tip to get reinforcement at the base and middle of fin. I don't recall right off hand, but his final fin thickness was still pretty thin at its maximum thickness. The Tomach fins are 1/8 inch all through and are not bevelled. You will have to bevel. If you add tip to tip to the Madcow fins, they are going to be pretty thick, and the ttt will add weight. You might think about CJ's Space Cowboy surface mounted technique with good filets. I can dig up the link if necessary. With a full 1/8 inch fin root surface for mounting, tip to tip may not be necessary, at least for K300. Not sure if people have tested on L935. Good luck with your decisions and build.

Click to expand...

I have looked through CJ's build many times, and that is the reason I asked if tip to tip would be necessary. I plan on beveling the fins to about one inch from the edge. If I were to do tip to tip, I probably wouldn't do TFish's method of 1/3, 2/3, and full. I would probably skip the 2/3 and do just a small piece over the fillet of higher weight glass (around 6-8 oz.), and then a full layer of lighter glass (around 3 oz.). Does this sound like a good plan? This will go along with the Proline fillets. I will probably wait to see how AlnessW does his tip to tip, and use that as a guide for mine.

As for updates to the build, I'm still waiting on epoxy, although today I picked up the machine bolts to bolt in the Aeropack retainer. I also made a rocket holder to use at launches. It hangs form the edge of my pop-up tent and can hold up to five rockets, with up to three of those being short rockets. I made it using seat-belt webbing, and used grommets to attach the loops.


Cheers,
Kyle Rodrigues

(And I think I may have found a name for this rocket. How does "Money Burner" sound? Still open to suggestions if anybody has one.)

Little update for today. I'm still waiting for epoxy, but I built my launch tower today. I found the wheels at a flea market yesterday for $5, and then got 3/4" EMT at Home Depot, and 1/2" all-thread at a local metal place. This is the result:


I made it 7 feet tall, just so I can be sure he rocket will be stable when it leaves with longer burn motors.

Also, for the tip to tip, I was thinking of This for the 1/3 layer, and then This for the full layer, so it will be a little thinner and lighter but still have strength at the joint. Any opinions on his?

Cheers,
Kyle Rodrigues

Good luck with the build, the tower looks solid! I also have a Tomach in the works too, but mine is a little different then yours.

Small update to the build.

I received a few small orders in the past week. I haven't done much because of midterms, but it is going back on the front burner now.

A few days ago I put together the bulkplates for the av-bay using Aeropoxy 6029. I deviated from the instructions and made both ends removable, since the whole av-bay will be removable. I ordered another bulkplate for the end of the nosecone from Rocketry Warehouse. I used the eyebolts and some toothpicks to align them, and removed them both once the epoxy had gelled so they wouldn't get stuck.
Here is a picture of the bulkplates being glued together:


Today I accomplished two things. The first was dealing with making the bulkplate on the end of the nosecone removable. I followed the way AlnessW did it in his build thread, since I am using his thread for tips and ideas. The only difference is that I used short pieces of all-thread instead of bolts for the epoxy to grab onto. Once I put the epoxy on, I set it vertical in front of a heater to dry. When I came to check on it about fifteen minutes later, the epoxy had run all the way down the inside of the tube. I guess as thick as Aeropoxy is, it still runs, and I'm sure the heat didn't help. So I quickly wiped out the epoxy and added more, but I still had to turn it over by hand every few minutes to keep if form running. So I came up with this:

I taped it to the end of my BBQ rotisserie, hoping that the slow rotation would keep it from running, and it seemed to work well. After a few hours of rotating, it gelled enough to be brought inside and put in front of the heater. Here is the final result: (ignore the pieces of wire, those were used as a spacer to set the couplers in more)

I may add some fiberglass to the inside like AlnessW did to strengthen it, but I'll decide that when I get to the tip to tip.

The other thing that I did today was get everything attached to the av-bay bulkplates. On one end there are two Doghouse Rocketry 3g charge wells with integrated terminals. And on the other end it is the same with the addition of an antenna for the Eggtimer TRS. It was a little tricky to get it all crammed onto the 54mm bulkplate, but it should work good. The reaosn for two charge wells on each end is for a redundant altimeter in the future, which will most likely be a StratologgerCF. I plan on making a sleeve from tubular kevlar to secure over the antenna to protect it from the ejection charges.


That is all I have done so far. I plan on ordering the materials to do the tip to tip in the next few weeks, although I will probably end up doing it after my L1 flight, because a club member is going to let me borrow his vacuum pump, but I can't get it until the next launch. I also need to get a longer av-bay, because I am using an extension cable from the TRS to the antenna, and the cable can't bend sharp enough inside the av-bay.

In the next week I plan on beveling the fins and attaching them, and getting the Aeropack retainer installed.

Cheers,
Kyle

Those charge wells look they came from Doghouse Rocketry. Been thinking about trying them...

rc dude said:

Little update for today. I'm still waiting for epoxy, but I built my launch tower today. I found the wheels at a flea market yesterday for $5, and then got 3/4" EMT at Home Depot, and 1/2" all-thread at a local metal place. This is the result:
View attachment 256408

I made it 7 feet tall, just so I can be sure he rocket will be stable when it leaves with longer burn motors.

Also, for the tip to tip, I was thinking of This for the 1/3 layer, and then This for the full layer, so it will be a little thinner and lighter but still have strength at the joint. Any opinions on his?

Cheers,
Kyle Rodrigues

Click to expand...

Like your tower. Did you tap the EMT to accept the allthread? Or, is there a nut on the inside of the EMT, and if so, how do you access it?

o1d_dude said:

Those charge wells look they came from Doghouse Rocketry. Been thinking about trying them...

Click to expand...

Yes they are the 3g ones from doghouse. I liked the idea of having the integrated terminals; it is one less thing I had to cram on the bulkplate. You are welcome to check them out at the next Snow Ranch launch.

Buckeye said:

Like your tower. Did you tap the EMT to accept the allthread? Or, is there a nut on the inside of the EMT, and if so, how do you access it?

Click to expand...

I welded some all-thread couplers to the EMT, making sure to keep the two aligned. that way I can remove the all-thread if I need to pack it down tighter. Here is a picture I took to show how I did it:

Disclaimer: welding galvanized metal can produce toxic gas, attempt at your own discretion. I had a fan blowing on it and held my breath.


Today I started marking out the bevel on the fins. Does 1/2" perpendicular from the edge sound like a good amount? For the tip to tip I will do the top layer about half way down the bevel, then sand the edge of the CF down to feather it out before putting the Proline 4500 on the edges. Does this sound good? Just wondering before I start sanding.

Today I beveled the fins. I tried making a jig to do it, but the beveled weren't coming out straight. I finally just used a portable belt sander secured upside down in a vise, and did it freehand. Then I cleaned them up a little with a sanding block. The bevels aren't perfect, but they will eventually be under the tip to tip. I also plan on scuffing up the fin roots and the airframe today in preparation for attaching the fins.

Fin bevels:


Cheers,
Kyle


I also decided to make a list of things I still need to do before it is flight ready:
Mount Aeropack retainer
Mount fins
Fillets
Install shock cord
Epoxy in nosecone coupler
Install screws to hold coupler into forward airframe
Drill shear pin holes
Get batteries for electronics
Ground test, ground test, ground test...

Small update for today. Over the past three days I have managed to get the fins attached with Aeropoxy 6029. I only did one fin per day, to minimize runs in the epoxy. I will work on the fillets in the next couple of days, doing two per day.
In the photos you can see the holes I drilled for the fillets to grab onto.


I also received an order from Madcow today. This included a 12"x12" nomex chute protector for the main, and a 8" CF coupler, since the 6" coupler that came with the kit is too short for my needs. Unfortunately my mind blanked when I ordered and I forgot that CF blocks RF signals, which wouldn't let the TRS GPS get a lock. So the coupler will be going back on Monday, and I will be searching for an 8" fiberglass coupler. I emailed Bay Area Rocketry to see if he had one, and if not I'll order one from Rocketry Warehouse.

Shock cord was also ordered. I have 15 yards of 1/4" tubular kevlar coming from Wildman. Since I am not getting a prefabricated shock cord, I have been practicing my knots, haha.

My to-do list is getting smaller!
Mount Aeropack retainer
Fillets
Install shock cord
Epoxy in nosecone coupler
Install screws to hold coupler into forward airframe
Drill shear pin holes
Get batteries for electronics
Ground test, ground test, ground test...


Cheers,
Kyle


Edit:
Another question I have that is unrelated to his build is about launch lug placement. For my Madcow Scooter, I placed the forward launch lug on the CG, and the rear launch lug at the rear end. Now I have ordered the payload kit for it, which extends it 10". Will I be ok with where the launch lugs are? They are now both behind the CG, as you can see in the pic.

Hey Kyle - all is looking good so far! At this rate you'll catch up to me fairly quickly...
A few responses of my own:

Personally I'm not going to bevel my fins until after the tip-to-tip is complete. I too, use a random orbital sander (freehand) with great results.
What are your thoughts on drilling holes in your fins for fillets?
Why the 8" coupler? For the av-bay?
Did your kit come with tubular nylon? IMO, knots are stronger than sewn loops.

Also, I assume your question about rail buttons is for a different project, since you've got the tower for this one. (Edit: yes, it is.) In my experience, rail button placements have nothing to do with CP/CG - just saying...

AlnessW said:

Hey Kyle - all is looking good so far! At this rate you'll catch up to me fairly quickly...
A few responses of my own:

Personally I'm not going to bevel my fins until after the tip-to-tip is complete. I too, use a random orbital sander (freehand) with great results.
What are your thoughts on drilling holes in your fins for fillets?
Why the 8" coupler? For the av-bay?
Did your kit come with tubular nylon? IMO, knots are stronger than sewn loops.

Also, I assume your question about rail buttons is for a different project, since you've got the tower for this one. (Edit: yes, it is.) In my experience, rail button placements have nothing to do with CP/CG - just saying...

Click to expand...

Thanks for the kind words. I need to get it done (or at least flyable) by April 4th. I plan on getting my L1 at the LUNAR launch. I am pretty sure I can do it, but the tip-to-tip will have to wait until after then. I'm looking forward to seeing your progress.

I have seen other people drill the holes for the filet epoxy to grab onto, and I figured it wouldn't hurt, so why not. And I beveled the fins first because it seemed easier to do when they weren't attached. I plan on running the top layer of CF partway down the bevel, then covering the leading edge with Proline 4500.

As for the 8" coupler, that is for the av-bay. I have Landru's 54mm sled to mount my TRS to. I also have an extension cable for the antenna that is mounted to the forward bulkhead. When the cable is attached to the TRS, it can't bend sharp enough to allow the bulkhead to close, so I decided to go with an 8" coupler, since I had extra room in the main parachute bay. That will also help to allow room for the backup altimeter, a StratologgerCF, and the three batteries to power it all. (TRS power, TRS deployment, and StratologgerCF).

Yes my kit did come with tubular nylon, but I ordered the 1/4" tubular kevlar so I wouldn't have to worry about protecting it from the ejection charges. I plan on knotting it, with a figure-eight follow through on the ends, and an alpine butterfly knot for the parachute attachment point.

Thanks for the info about the Madcow Scooter. I was pretty sure it would work, but most people say the forward one should be on the CG, so I was just asking.


Now I just need to stop dragging my feet and do the fillets, but I am nervous about using Proline 4500, as most people say it is hard for first-timer. I guess I'll just need to suck it up and do it, haha.

Cheers,
Kyle

Oh boy - April 4 is this weekend!! Hope you can get a flight in...
Never heard of the hole-drilling trick before, but I can't imagine why it would hurt. As far as beveling goes, yeah, I too find it much easier to do before the fins are attached. But with the tip-to-tip I didn't want to do them twice - we'll see.

I think you'd definitely need the extra room if you're using 3 altimeters. (I could barely fit 2 of them plus batteries and switches.) It was tempting to use LiPo batteries in mine, but I've never fiddled with them before PLUS you have to use a resistor when powering a Raven with one. Keep it simple.

I use the "Binder Design knot" as my standard for tying tubular nylon - no idea what it's really called, but it appears in all of Mike's instruction sheets.

And as for rail buttons, I've seen them every whichway before without issue - up to you really.

AlnessW said:

Oh boy - April 4 is this weekend!! Hope you can get a flight in...
Never heard of the hole-drilling trick before, but I can't imagine why it would hurt. As far as beveling goes, yeah, I too find it much easier to do before the fins are attached. But with the tip-to-tip I didn't want to do them twice - we'll see.

I think you'd definitely need the extra room if you're using 3 altimeters. (I could barely fit 2 of them plus batteries and switches.) It was tempting to use LiPo batteries in mine, but I've never fiddled with them before PLUS you have to use a resistor when powering a Raven with one. Keep it simple.

I use the "Binder Design knot" as my standard for tying tubular nylon - no idea what it's really called, but it appears in all of Mike's instruction sheets.

And as for rail buttons, I've seen them every whichway before without issue - up to you really.

Click to expand...

Yep, I'll be busy in the next few days finishing up the loose ends. It's a good thing I am on Spring break this week. Any updates for your Tomach?

I think you misunderstood when I explained my altimeters. I only have two, the TRS and the StratologgerCF, not three. There will be three batteries because the TRS uses two, so in case the deployment side shorts out, the tracking will still work. The lipos I purchased are nice and small, and two of them fit in place of one 9V battery on the sled. The Stratologger will be mounted to the back of the sled above the battery compartment, and the third battery will be mounted on the bottom of the sled.

As for the knot, I think I am going to stick with the figure-eight follow through. It is the same knot used for rock climbing and search and rescue, and it retains a lot of the rope's strength when tied. It is also fairly easy to undo if I need to, but won't come undone by itself.


As for an update, I just finished doing the first set of fillets about 30 minutes ago. It was my first time using Proline 4500, and also my first time doing fillets that weren't cosmetic. I think they came out good. I used a washer in vice-grips to pull them out, which worked well. They are currently drying, and I will do another set in a few hours, and the final set tomorrow. Let me know what you think.


To do still:
Finish fillets
Epoxy nose cone coupler
Install retainer with bolts
Drill vent holes
Install av-bay with bolts
Tie shock cord
Make drogue chute
Wire up altimeter bay
Ground test
Put threadlock on nosecone tip
Make retainer extension
Drill shear pin holes

Looks like I'll be busy

rc dude said:

Yep, I'll be busy in the next few days finishing up the loose ends. It's a good thing I am on Spring break this week. Any updates for your Tomach?

I think you misunderstood when I explained my altimeters. I only have two, the TRS and the StratologgerCF, not three. There will be three batteries because the TRS uses two, so in case the deployment side shorts out, the tracking will still work. The lipos I purchased are nice and small, and two of them fit in place of one 9V battery on the sled. The Stratologger will be mounted to the back of the sled above the battery compartment, and the third battery will be mounted on the bottom of the sled.

As for the knot, I think I am going to stick with the figure-eight follow through. It is the same knot used for rock climbing and search and rescue, and it retains a lot of the rope's strength when tied. It is also fairly easy to undo if I need to, but won't come undone by itself.


As for an update, I just finished doing the first set of fillets about 30 minutes ago. It was my first time using Proline 4500, and also my first time doing fillets that weren't cosmetic. I think they came out good. I used a washer in vice-grips to pull them out, which worked well. They are currently drying, and I will do another set in a few hours, and the final set tomorrow. Let me know what you think.
View attachment 259707

To do still:
Finish fillets
Epoxy nose cone coupler
Install retainer with bolts
Drill vent holes
Install av-bay with bolts
Tie shock cord
Make drogue chute
Wire up altimeter bay
Ground test
Put threadlock on nosecone tip
Make retainer extension
Drill shear pin holes

Looks like I'll be busy

Click to expand...

Fillets are looking good, are you not going to do a single ply T2T? The AV bay will be tight with 3 batteries and the two altimeters.

rc dude said:

Yep, I'll be busy in the next few days finishing up the loose ends. It's a good thing I am on Spring break this week. Any updates for your Tomach?

I think you misunderstood when I explained my altimeters. I only have two, the TRS and the StratologgerCF, not three. There will be three batteries because the TRS uses two, so in case the deployment side shorts out, the tracking will still work. The lipos I purchased are nice and small, and two of them fit in place of one 9V battery on the sled. The Stratologger will be mounted to the back of the sled above the battery compartment, and the third battery will be mounted on the bottom of the sled.

As for the knot, I think I am going to stick with the figure-eight follow through. It is the same knot used for rock climbing and search and rescue, and it retains a lot of the rope's strength when tied. It is also fairly easy to undo if I need to, but won't come undone by itself.


As for an update, I just finished doing the first set of fillets about 30 minutes ago. It was my first time using Proline 4500, and also my first time doing fillets that weren't cosmetic. I think they came out good. I used a washer in vice-grips to pull them out, which worked well. They are currently drying, and I will do another set in a few hours, and the final set tomorrow. Let me know what you think.

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Oops - you're right, I did read that wrong. I believe the ARTS2 is another altimeter that requires 2 batteries. Fillets look good too! I've never tried using that black goo before. As for my update - I did another set of fillets the other day.
A couple other thoughts I had:

rc dude said:

Epoxy nose cone coupler

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Will your nosecone bulkhead be removable?

rc dude said:

Make drogue chute

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Do you really need one?

rc dude said:

Put threadlock on nosecone tip

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What are your thoughts on this?

mpitfield said:

Fillets are looking good, are you not going to do a single ply T2T? The AV bay will be tight with 3 batteries and the two altimeters.

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I am planning on doing a two layer T2T, with the first layer going 1/3 up the fins, and the second layer going all the way to halfway down the bevels. The edges will be coated in Proline 4500 to prevent delamination.

Yes it will be a tight fit, but I ordered a longer coupler, so it should work out alright. The batteries are pretty small, only half the size of a 9V each.

AlnessW said:

Oops - you're right, I did read that wrong. I believe the ARTS2 is another altimeter that requires 2 batteries. Fillets look good too! I've never tried using that black goo before. As for my update - I did another set of fillets the other day.
A couple other thoughts I had:

Click to expand...

The Proline is actually easier to work with then I expected. I read many threads on here about working with it, and I read many people saying it is hard to work with the first time you use it. The only problem I seemed to have was a few small bubbles that were in the epoxy and made about four small pinholes, but this will be covered by the T2T, so I'm not to worried about it. I managed to finish all three sets today, so it is drying so I can continue work on it tomorrow.

AlnessW said:

Will your nosecone bulkhead be removable?

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My nosecone bulkhead will be removable. I copied the way you are doing yours, where there are all-thread couplers epoxied inside the coupler, and the bulkplate screws into that. That way the coupler is epoxied into the nosecone, but I can still access the inside to put a tracker in there.

AlnessW said:

Do you really need one?

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Probably not, but it just makes me feel a little more comfortably since I have not done dual deploy before. I know I said at the beginning of this thread that I was going to do drogueless, but have since changed my mind. In case the main does not deploy, it will fall slower with a drogue then drogueless, and hopefully will have less damage. Even then it will be a small drogue, probably a 12" homemade hemispherical chute.

AlnessW said:

What are your thoughts on this?

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I don't plan on removing it any time soon, so I figure threadlock won't hurt. My way of thinking is if something doesn't add weight/drag, but helps improve something else, it is worth doing.


The list of things to do is getting smaller!
To do still:
Epoxy nose cone coupler
Install retainer with bolts
Drill vent holes
Install av-bay with bolts
Tie shock cord
Make drogue chute
Wire up altimeter bay
Ground test
Put threadlock on nosecone tip
Make retainer extension
Drill shear pin holes

Waiting for flight update.

Today I got a lot done, but I still have a ways to go. At least I haven't procrastinated as much as I do with writing papers for my classes, haha.

The fillets fully cured overnight, although there are few pinhole bubbles that worked their way to the surface. I am not going to deal with them now, as they will be filled in with the T2T later on.


The first thing I did today was cut my shock cord to length. I am going to be using 20 feet for both the drogue and the main. I still have to tie it up though.

Next I did some of the wiring in the av-bay. I have almost all of the wiring for the TRS done, and will have to wire up the Stratologger Saturday morning when I pick it up. Talk about cutting it close... I also received my order of LEDs from Amazon, so I did some vacuum testing of the TRS in my Foodsaver, and it seemed to work perfectly. I'll be taking the Foodsaver and a power inverter to the launch on Saturday to test the Stratologger in combination with the TRS as well. Here are a few pictures of what I have done so far:


Next I made the drogue chute. It is a 12 inch, four gore, 25% hemispherical chute. I got the templates from https://scottbryce.com/parachute/spherical_parachute.html, which I have used for the other chutes I have made, including the 48" 16 gore chute that will be the main for the Tomach. Here are two pictures of the chute, and the second picture has a ruler for size reference.


The last thing I did today was drill the holes for the bolts that hold the retainer and coupler, and the holes for the shear pins in the lower body tube. I laid the rocket in a piece of angle iron to make sure it was aligned when I drilled the holes. I think they came out pretty good, and I will glue in the nuts on the inside tomorrow.


One question, will having one of the altimeter vent holes right behind one of the bolts be bad? I am planning on using three holes, with one behind one of the bolts, and the other two about thirty degrees away. This is so I can access the screw switches on the sled through them. It would look like this (blue is bolts, red is vent holes):

Does anybody know if this would impact the altimeter readings?

I didn't drill the shear pin holes for the nose cone yet because I still have to epoxy in the coupler in the base of the nose cone. Will Proline be good enough epoxy for this? I would rather not use Aeropoxy as it takes a long time to cure, but I will if the higher strength would help.

The other thing I did today was go to my local metal/fastener supplier, Blue Collar Supply, and get some odds and ends that I needed. This included allthread for both the retainer extension, and the longer av-bay. I also purchased some round steel plates to use as a blast deflector for my launch tower.


The list of things to do is getting smaller!
To do still:
Epoxy nose cone coupler
Drill vent holes
Tie shock cord
Wire up altimeter bay
Ground test
Make retainer extension

Until tomorrow's update,
Kyle

Looks good Kyle! Sounds like you're doing the Vern-style nosecone anchors? I usually recommend these so you can use your nosecone as a tracker/GPS bay, like you mention.

I've never tried using threadlocker on a nosecone tip - but I've also never had occasion to remove one EXCEPT if I'm using it as a shockcord attachment point, such as in my 3" MD. Drogue chute looks good!
Are you using a MissileWorks sled? I see you're using their screw switches, much like myself. I slightly prefer the Featherweight screw switches (a lot smaller) but the MissileWorks ones are a bit cheaper.

What are your screws tapped into?

Your vent holes will probably be fine, but for extra insurance I'd add a few more on the other side of the bay.

Hope theses help: I have a 6gxl case too and the biggest motors are cool. If I heard u right: vent holes should not be placed below any protrusions. It can mess up readings. I read this in one of the AV bay instructions, or the missile works instructions, or the rocket book. You probably used the formula for av bay vent sizing, right? I have used the Eggfinder TX and just got TRS. The instructions seem a little confusing, you might want to look up a couple of threads on this forum. One guy had a problem turning it on at the pad.

https://m.youtube.com/watch?v=C2IKh840XFk
Just a thought, I used a small motor to test out the ejection charges & electronics prior to going out of sight with a large motor. In the flight attached video, I would have lost it if the gps EggFinder didn't work

rc dude said:

One question, will having one of the altimeter vent holes right behind one of the bolts be bad? I am planning on using three holes, with one behind one of the bolts, and the other two about thirty degrees away. This is so I can access the screw switches on the sled through them. It would look like this (blue is bolts, red is vent holes):
View attachment 259841
Does anybody know if this would impact the altimeter readings?Kyle

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Wow Kyle, it is looking great, love the 3D printer altimeter sled. I have 2 of those for other builds so it's nice to see what others have done with theirs.

As far as the vent holes I will repeat the advice I was given when I asked a similar question. In general you want to keep the vent holes away from anything that can disturb or break the laminar airflow. Having said that you may be fine, but I would try a test flight with engine backup for the apogee event as this is primarily when it will be an issue. I used that approach when I put vent holes in a nosecone and the back up was not required because it went off without any issues.

NattyDread said:

https://m.youtube.com/watch?v=C2IKh840XFk
Just a thought, I used a small motor to test out the ejection charges & electronics prior to going out of sight with a large motor. In the flight attached video, I would have lost it if the gps EggFinder didn't work

Click to expand...

That just reinforces my thoughts on drogue vs drogueless.