Sharon's 4" Jimbo Jart

Rrwjr · Jul 7, 2014

SinfulDarkLord said:
Just a reminder for next time, the instructions say allow 15 minutes for it to de-gas.

+1
After talking with Crazy Jim and Tim, I let mine set for at least 25 minutes before I apply it on external fillets. It seems to set up better. I do stir mine at about 15 minutes, and 20 minutes as well as once more before applying and that seems to get the air bubbles out.

AfterBurners · Jul 7, 2014

Rrwjr said:
+1
After talking with Crazy Jim and Tim, I let mine set for at least 25 minutes before I apply it on external fillets. It seems to set up better. I do stir mine at about 15 minutes, and 20 minutes as well as once more before applying and that seems to get the air bubbles out.

Never used it, what is work time on it before it sets up?

REK · Jul 7, 2014

AfterBurners said:
Never used it, what is work time on it before it sets up?

45 minutes is where I believe it starts to become a tad difficult to form. I usually wait until 30 minutes, since this is the peanut butter stage. This is where you want to make the fillets since it retains its shape.

Alexander Solis

Level 1 - Mariah 54 - CTI-I100 Red Lightning Longburn - 6,345 Feet

AfterBurners · Jul 7, 2014

SinfulDarkLord said:
45 minutes is where I believe it starts to become a tad difficult to form. I usually wait until 30 minutes, since this is the peanut butter stage. This is where you want to make the fillets since it retains its shape.

Alexander Solis

Level 1 - Mariah 54 - CTI-I100 Red Lightning Longburn - 6,345 Feet

Wish I could make fillets like most of you. Mine are OK.

With beveled leading and trailing edges you can get the epoxy to stop right at the leading and trailing edges and it would look great, but what if your leading and trailing edges aren't beveled and are just "square" How do you get the epoxy to properly "wrap" around the edges, without it dripping down the side of the rocket? If you have it laying down and you are doing fillets on adjacing fins I would think it would run?

Hardline · Jul 7, 2014

Rrwjr said:
+1
After talking with Crazy Jim and Tim, I let mine set for at least 25 minutes before I apply it on external fillets. It seems to set up better. I do stir mine at about 15 minutes, and 20 minutes as well as once more before applying and that seems to get the air bubbles out.

AfterBurners said:
Never used it, what is work time on it before it sets up?

I've never let it sit that long so I don't know how it would work, perceptually it sets up ALOT quicker when you add color. Once I have done a set of fillets I wait 90 minutes before doing the next set.

I'll try letting the mix set for 25 minutes before trying it on my next build, worth testing.

WoShuGui · Jul 7, 2014

Great build thread. Finally got to fly my Jimbo Jart at ROCStock last month. [video]www.youtube.com/watch?v=uLvPmKpb6Iw[/video]

Good luck vs CJ, but I 'd watch carefully. Word is he has some kind of super motor starter he uses in drag races. I'm sure he'd let you use one if you asked though

My RocketPoxy experience has been a little different. I do not see the number of bubbles you and Wayco are getting. Sorry to see all your recent headaches. I am building in a similar low humidity warm climate and it looks like we use similar mixing and application methods. I do all my fillet mixing in the little 1-2 oz. cups using chopsticks to transfer first the white resin then the amber hardener from the pint jars. Like a honey dipper. Mixing is with a clean chopstick that is also used to apply and work the epoxy into the fillet before smoothing. Never have used heat. Maybe there is some manufacturing batch variability. I am starting a new set of jars and will look for any differences. The 15 minute airing time is interesting since 15 minutes after mixing, RocketPoxy is already starting to get pretty thick. I guess that would be okay for one set of external fillets though. By 30 minutes, in my experience, the RocketPoxy has set. It can be molded like silly putty, but it is not going to settle into a fillet very well. That gives less than 15 minutes of working time. Not much as slow as I am. Certainly no time to sip wine or in my case, guzzle diet cherry Pepsi. :blush:

Rrwjr · Jul 7, 2014

Hardline said:
I've never let it sit that long so I don't know how it would work, perceptually it sets up ALOT quicker when you add color. Once I have done a set of fillets I wait 90 minutes before doing the next set.

I'll try letting the mix set for 25 minutes before trying it on my next build, worth testing.

I should have mentioned, my times were based on adding color (black). I haven't used it natural colored yet.

azheninger · Jul 7, 2014

Great job on the build and excellent job documenting it!

jd2cylman · Jul 7, 2014

WoShuGui said:
My RocketPoxy experience has been a little different. I do not see the number of bubbles you and Wayco are getting. Sorry to see all your recent headaches. I am building in a similar low humidity warm climate and it looks like we use similar mixing and application methods. I do all my fillet mixing in the little 1-2 oz. cups using chopsticks to transfer first the white resin then the amber hardener from the pint jars. Like a honey dipper. Mixing is with a clean chopstick that is also used to apply and work the epoxy into the fillet before smoothing. Never have used heat. Maybe there is some manufacturing batch variability. I am starting a new set of jars and will look for any differences. The 15 minute airing time is interesting since 15 minutes after mixing, RocketPoxy is already starting to get pretty thick. I guess that would be okay for one set of external fillets though. By 30 minutes, in my experience, the RocketPoxy has set. It can be molded like silly putty, but it is not going to settle into a fillet very well. That gives less than 15 minutes of working time. Not much as slow as I am. Certainly no time to sip wine or in my case, guzzle diet cherry Pepsi. :blush:

Mine has been different yet... I build in my basement which is about 70 ish give or take. At 15 minutes my RocketPoxy was still runny. Most of my fillets ran a little. Left the lids off the jars for a day, per a certain person's advice. Seems to have helped a lot.

OK, Jason and Steve, it should read "When I build in the basement". Yeah yeah, I know, get building that Madd Max kit, or that 4" Vindicator kit, or that 8" Gizmo XLV, or that PML 1/2 Scale Patriot, or that, or that, or that.......... :facepalm:

Adrian

Hardline · Jul 7, 2014

WoShuGui said:
Great build thread. Finally got to fly my Jimbo Jart at ROCStock last month. [video]www.youtube.com/watch?v=uLvPmKpb6Iw[/video]

Good luck vs CJ, but I 'd watch carefully. Word is he has some kind of super motor starter he uses in drag races. I'm sure he'd let you use one if you asked though

My RocketPoxy experience has been a little different. I do not see the number of bubbles you and Wayco are getting. Sorry to see all your recent headaches. I am building in a similar low humidity warm climate and it looks like we use similar mixing and application methods. I do all my fillet mixing in the little 1-2 oz. cups using chopsticks to transfer first the white resin then the amber hardener from the pint jars. Like a honey dipper. Mixing is with a clean chopstick that is also used to apply and work the epoxy into the fillet before smoothing. Never have used heat. Maybe there is some manufacturing batch variability. I am starting a new set of jars and will look for any differences. The 15 minute airing time is interesting since 15 minutes after mixing, RocketPoxy is already starting to get pretty thick. I guess that would be okay for one set of external fillets though. By 30 minutes, in my experience, the RocketPoxy has set. It can be molded like silly putty, but it is not going to settle into a fillet very well. That gives less than 15 minutes of working time. Not much as slow as I am. Certainly no time to sip wine or in my case, guzzle diet cherry Pepsi. :blush:

Great video, fun times.

And I'll have to "talk" to CJ before our Drag Race.......

Hardline · Jul 7, 2014

azheninger said:
Great job on the build and excellent job documenting it!

Thanks Bob, want to do TRAPHX proud.

blackjack2564 · Jul 7, 2014

WoShuGui said:
Good luck vs CJ, but I 'd watch carefully. Word is he has some kind of super motor starter he uses in drag races. I'm sure he'd let you use one if you asked though

:

Umm yeah... this is what it did when we were SUPPOSED to be flying 3 grain white thunder motors...... but I knew Tim would cheat. He stuck a V-max in, last minute. [I figured he would] so I stuck with the white thunder & a starter made with secret sauce! LOL

Spanked him out of the hole, but alas he caught up & passed me about 150 ft up.

BUT I did get the hole shot!!!@$$#Q!.

[pic by David Reese]

Yes Sharon I will make you one.

REK · Jul 12, 2014

AfterBurners said:
Wish I could make fillets like most of you. Mine are OK.

With beveled leading and trailing edges you can get the epoxy to stop right at the leading and trailing edges and it would look great, but what if your leading and trailing edges aren't beveled and are just "square" How do you get the epoxy to properly "wrap" around the edges, without it dripping down the side of the rocket? If you have it laying down and you are doing fillets on adjacing fins I would think it would run?

Sorry for the late response. The rocketpoxy has certain stages in its curing cycle. I believe John told me there was three. If I remember correctly the first stage is the low viscous stage so you can pour, mix, etc. The second stage should be the 15 minutes for de- gas and is just a little thicker, but still flows. The last stage is the (after 30 minutes) thick viscous stage that is pretty much like peanut butter. I'm sure you know how peanut butter can be

. After the 15 minutes this is where you want to put on the epoxy and prevent drips after 30 minutes have passed. When it reaches the peanut butter stage use the dowel, pvc, etc. to shape your fillets and presto. You will have very pretty fillets, whether the fins are beveled or square.

These are the ones I made not too long ago for my speedy gonzales rocket.

ImageUploadedByRocketry Forum1405210478.681977.jpg

Sorry if I hijacked the thread.

Alexander Solis

Level 1 - Mariah 54 - CTI-I100 Red Lightning Longburn - 6,345 Feet

Hardline · Jul 13, 2014

blackjack2564 said:
Yes Sharon I will make you one.

oooohhhhhh - thanks CJ!

Hardline · Jul 13, 2014

My last BUILD post was a page back, but I've made progress in the last couple of days.

I had started working on my avbay and got my stratologger posts in when I had a batch of work for my business come in.

By the time I had finished my work and got back to my build I found that in the meantime Wayne had done this:

He hot glued down the magnetic switch, added a screw in the ground and tinned/soldered the leads. Thanks honey!

So I attached the Dog House Rocketry Battery Box (shameless plug: https://doghouse.blastzone.org/battery-holder-9v.html) and wire-tied the battery into place, add the stratologger and red-locktighted the posts and here is the finished sled:

Unfortunately, in the process I drilled a hole into my cutting board as you can see in the above photo. I guess that if you are going to use a piece of wood underneath, you should actually make sure you are drilling where the wood is :facepalm:

Added charge cups to the bulkplates:

I cut a piece of all thread 1" longer than the avbay/coupler assembly, added an I-nut and nut on either side of the nose end and used red locktite to secure the I-nut into place. The other end I put an I-nut or EYE-nut. Whatever!

I got to thinking about that I-nut. Wayne and I just purchased a Mongoose 75 for our team build and while in the process of getting data about how others have built theirs we read a posting from Kevin (Kaycee) where he wrote:

The rocket was drogueless due to the wind, and after a ~3+ minute tumble back to earth the eyebolt that was double-nutted -and- LocTited unscrewed a few thousand feet over the field on the way down.

his full post can be read here:

https://www.rocketryforum.com/showt...are&p=731434&highlight=mongoose+75#post731434

Well, I got a little nervous so I had Wayne drill a hole through the all thread and I stuck a cotter pin through it:

No way is that sucker going to unscrew, dumping my electronics in mid-air. Yeah, I'll have to work with it before and after every flight, but I put another 5 cotter-pins into a small bag and added it to the field box. Just in case I drop the cotter pin in the field. What is that phrase "for want of a nail"....?

https://en.wikipedia.org/wiki/For_Want_of_a_Nail

Hardline · Jul 13, 2014

Next up: Retention.

3 feet of Kevlar cord with quick links tied with non-slip mono knot:

https://www.animatedknots.com/nonsl...ge=LogoGrog.jpg&Website=www.animatedknots.com

Tied the kelvar to 12' of tubular nylon on the main side/25' on the drogue with double fisherman's bend:

https://www.animatedknots.com/doubl...ge=LogoGrog.jpg&Website=www.animatedknots.com

Taped the important areas:

Hardline · Jul 13, 2014

I asked Wayne to make me a Nomex pocket for my small apex Spherachutes drogue (another shameless plug because these are just AWESOME https://spherachutes.com/items/drogues/sm-apex-dr-detail.htm) and a 14 X 14" Nomex protector for my 40" Recon.

Sharon does not sew.

Tied an overhand loop to attach the tubular nylon to the kelvar on the fincan

Taped it all up, too. Ordered more tape from Amazon.com...... https://www.amazon.com/gp/product/B002P2ZNJE/?tag=skimlinks_replacement-20

Another overhand loop on the nose side:

Hardline · Jul 13, 2014

Ok - the parachute. Wayne and I learned this from CJ, so credits to the man.

Starting on one end of the protector, added the 40" Recon. The overhand loop in the tubular nylon is about 5' from the nosecone and I used a 1/8th inch quick link

Rolled the parachute one turn,tucking it a small as practical, then flaked the parachute lines against the nomex.

Another roll and I added the flaked tubular nylon. I have over 500 skydives and the last thing I want is to have my parachute lines anywhere near the tubular nylon lines. It can be a Bad Thing.....

Making the burrito:

Hardline · Jul 13, 2014

Time to test charges.

Took out the sled, don't need it for the tests, and set up it up by running the igniters out of separate static ports and labelled them for Main and Drogue.

measured 1.2 g into the charge cups with our handy Lee Precision Powder Measure cup: https://www.amazon.com/gp/product/B000N8OIE8/?tag=skimlinks_replacement-20

Made sure the tip of the igniter was all the way down in the cup, added a little dog barf and taped over the cup

Added a casing with tape over the end to keep the inside pressurized

Put together the rocket:

Set it up outside

and the first test was not as enthusiastic as I would like. So, reset, added black power to the brim and test number 2 in 108 Fahrenheit degree temperature:

Since both drogue and main tested acceptably, I installed the rail buttons

GAWD, look at the bubbles in the fillets.. :eyeroll:

Since I forgot to draw my rail button line during the first part of my build I used a piece of paper. Taping one side of the paper to the middle of one fin along the rear edge of the rocket I smoothed it over to the next fin and used a pencil to mark the centerline of that fin on the paper. Folded the paper in half from that mark and now I have the half-way measurement for the rail buttons. Made a mark at that halfway measurement, then moved the paper up to the upper fin area and made another mark. Not trusting the upper mark, I used a piece of angle iron to make sure I was aligned properly and drew a line up about 20 inches along that middle mark. I did this with pencil since it erases right back off again.

Then I measured my motor mount inside to the edge of my retainer and then measured that same amount on the outside and made my upper rail button mark just under. This way my drogue won't get caught on the inside by the rail button screw. Then I measured from the rear of the rocket to the rear centering ring and added the lower rail button mark just above the rear centering ring. Drilled and installed:

Hardline · Jul 13, 2014

Well, here it is folks, ready to take to Airfest over Labor Day. It weighed in at 6.8 lbs without motor/casing:

My plan is to fly it first on a AeroTech K513 Fast Jack which sims to about 4800'. After a (hopefully) successful first flight I'll be hounding CJ for our Drag Race.

In the meantime I'm off to the next project, which is my 6" Stinger and it will be my first 75 mm build. Watch for a build thread on it soon.

Here's the 4" Jart and the 6" Stinger

Thanks for following this thread. I appreciate any and all questions or comments.

REK · Jul 13, 2014

Good luck with the flight and great rocket.

Alexander Solis

Level 1 - Mariah 54 - CTI-I100 Red Lightning Longburn - 6,345 Feet

watheyak · Jul 13, 2014

Looking good! Have fun at Airfest!

o1d_dude · Jul 13, 2014

Excellent build thread, Sharon.

Lotta good stuff in there. Even an old dog can learn a couple of new tricks from following along.

Thanks!

WoShuGui · Jul 14, 2014

Hardline said:
Well, here it is folks, ready to take to Airfest over Labor Day. It weighed in at 6.8 lbs without motor/casing:

My plan is to fly it first on a AeroTech K513 Fast Jack which sims to about 4800'. After a (hopefully) successful first flight I'll be hounding CJ for our Drag Race.

Uhh... you should get about 6,000 on a K513FJ... My Jimbo Jart weighs in at 7.5 lbs, (overbuilt AV bay and a LOT of paint) and still hit 3,300' on an AT J460T dragging a Mobius camera taped to the side. Sure would hate to see you lose your Jart before the big show down with CJ!

Great build thread by the way. I should try the deployment bag and packing ideas. My main parachutes end up with flak holes no matter how much nomex I wrap around them.

AfterBurners · Jul 14, 2014

Excellent job Sharon!!

So real quick can you post a picture of the Recon chute? I never seen one displayed and I wanted to get one. but on WM's site they don't have any pictures?

Thanks!!

Hardline · Jul 14, 2014

AfterBurners said:
Excellent job Sharon!!

So real quick can you post a picture of the Recon chute? I never seen one displayed and I wanted to get one. but on WM's site they don't have any pictures?

Thanks!!

Wayne had it somewhat laid out in post #45 here:

https://www.rocketryforum.com/showthread.php?66950-Wayco%92s-Dark-Star-Extreme&p=731822#post731822

I'll look through some pictures and see if I have one on descent. Edit: I seem to have a lot of pictures of rockets going up, and rockets on the ground but much of nothing of rockets in descent.

One on the ground:

Rrwjr · Jul 14, 2014

WoShuGui said:
Uhh... Great build thread by the way. I should try the deployment bag and packing ideas. My main parachutes end up with flak holes no matter how much nomex I wrap around them.

Are you using redundant charges? This was the first rocket I used redundant charges on ( practice for L3). After my first flight I found I had little holes in my chute ( a Reacon as well, great chutes). I found that my redundant charge was causing the issue and I put a short "y" tether for the main so the chute was further away from the redundant charge ( instead of being right on the eyebolt coming off of the AV bay) and that solved my problem.

AfterBurners · Jul 14, 2014

Thanks Sharon! Now I have an idea what they look like. (4) shroud lines = less tangles

WoShuGui · Jul 14, 2014

Rrwjr said:
Are you using redundant charges? This was the first rocket I used redundant charges on ( practice for L3). After my first flight I found I had little holes in my chute ( a Reacon as well, great chutes). I found that my redundant charge was causing the issue and I put a short "y" tether for the main so the chute was further away from the redundant charge ( instead of being right on the eyebolt coming off of the AV bay) and that solved my problem.

Thanks; that is a real possibility. I do use backup charges. I would think having the chute up near the nose cone would avoid this, but maybe 12' is still too close. Especially since the backup has a little more powder. Funny that I seem to have this problem more with the Reacon. Perhaps they are opening wider with the 4 lines and getting hit more. I will try the "y" tether too.

blackjack2564 · Jul 15, 2014

AfterBurners said:
Excellent job Sharon!!

So real quick can you post a picture of the Recon chute? I never seen one displayed and I wanted to get one. but on WM's site they don't have any pictures?

Thanks!!

For all intents & purposes they are Sky-angle clones, which have been tweaked to improve performance.:grin:

Sharon's 4" Jimbo Jart

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