bandman444
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No! Shhhhh. That’s a secret still. (That project is for a completely different Tripoli Record category!)
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Bryce's Handicap Record Quest: NSL 2024
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bandman444
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The Tripoli Records categories have some strange and unique cut offs. As you mentioned the Handicap records end at G, but for the Single-Stage Records, they end at F, for the Hybrids it ends at H, and the EX categories go down to 24mm motors. There are a ton of complicated and probably historical reasons that those are the case, but in general, (and at least historically) Tripoli keeps the high power records, and NAR keeps the low power records.
I could see this derailing the thread, so if someone wants to discuss this further, start a separate thread and tag me in it, or send me a PM and I can provide more details or context.
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For the larger sizes, you might look at Fruit Chutes Iris Ultras. You can get a higher Cd from a smaller chute, and they pack really small, if you know how to do it. I’ll be teaching some college students how to pack them tomorrow.
You might ask Top Flight or Front Range if they’d make you some chutes from ZP nylon in the smaller sizes. It’s a little harder to pack because it’s really slick - same stuff your Rocket Rage chutes are, if I remember correctly. But it will let you use a slightly smaller chute, which means less weight.
bandman444
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Thank you Steve for chiming in and congratulations to you and your daughter for setting NAR and FAI records! (If I thought the TRA single stage records were tough, the NAR and FAI competitions just blow my mind. I’ve always wanted to try my hand at the RC Boost Glide since combining hobbies sounds fun)
Please feel free to comment any thoughts, papers, research, or ideas you have about flying these kinds of “high” performance rockets.
Oh, and thank you for the kind words regarding the Records Committee, I know Mark and others on the Committee have worked really hard to continuously improve the clarity and accessibility of the records information and process.
bandman444
Well-Known Member
It doesn’t have to, and you might be hinting toward the fact that some NAR record rockets will attach their chute to the body tube center of mass to encourage the rocket to come down horizontally versus vertically. This has the benefit of using the body as some of the drag producing element on descent, and also may protect the aft end on landing.
I’m not sure I plan to use this technique for these flights, but we shall see.
bandman444
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The tube I was laying up for the H and I record rockets was so impossibly thin, I doubt it could have soaked up very much epoxy at all. When I layup big sonotube tube rockets, I do make sure to pre-wet out the tube to prevent too much soaking.
The challenge with these dang sleeves is that they act like Chinese finger traps when ever they hit a snag or sticky spot. It the tube sections are short, not a problem, but with larger and long tubes, it is a really tough challenge to get the sleeve on an epoxy soaked tube.
MClark
Well-Known Member
On the Al mandrel I wax it, layer of thin plastic (like a dry cleaners bag) then braid. Vacuum bagged. Mother dog to get off.
Wound cones.
Nose was PVC foam on a 1.5” diameter aluminum bar to hold rigid in lathe.
Do not remove from lathe until finished.
In lathe foam shaped, holes filled with drywall spackle then covered with plastic.
To wind I used a tray of resin on carriage to wet tow. Guided and held tension with fingers. Tow came off roll, under metal bar to keep immersed in epoxy. Epoxy squeezed into tow and excess removed with fingers.
End of tow tied to pin stuck in foam. Lathe at slowest RPM. First wraps are straight around laying tow right next to previous. Then unidirectional going longitudinal, wrap, eventually did angled wraps. Practice on something expendable.
Tip was two layers of cloth with edge under wrap. Vacuum bag.
Cure, sand, fill, sand………..turn shank to diameter. Remove foam.
Tail cone is way easier.
Same 1.5” bar, thin motor mount tube, (leave long both ends), foam repeat above.
In tail foam was left in. Slots for fins cut with Dremel tool attached to tool post.
Really primitive. But can be made to work.
I will do again.
Wound cones.
Nose was PVC foam on a 1.5” diameter aluminum bar to hold rigid in lathe.
Do not remove from lathe until finished.
In lathe foam shaped, holes filled with drywall spackle then covered with plastic.
To wind I used a tray of resin on carriage to wet tow. Guided and held tension with fingers. Tow came off roll, under metal bar to keep immersed in epoxy. Epoxy squeezed into tow and excess removed with fingers.
End of tow tied to pin stuck in foam. Lathe at slowest RPM. First wraps are straight around laying tow right next to previous. Then unidirectional going longitudinal, wrap, eventually did angled wraps. Practice on something expendable.
Tip was two layers of cloth with edge under wrap. Vacuum bag.
Cure, sand, fill, sand………..turn shank to diameter. Remove foam.
Tail cone is way easier.
Same 1.5” bar, thin motor mount tube, (leave long both ends), foam repeat above.
In tail foam was left in. Slots for fins cut with Dremel tool attached to tool post.
Really primitive. But can be made to work.
I will do again.
boatgeek
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If it's got a smooth inner surface and a smooth outer surface, then it's almost certainly solid all the way through. On my last sleeve layup, I had some patches where the inner surface was wetted out but not smooth. I didn't use heat shrink or any other consolidation besides rollers.
And now for something completely different...
OK, here's some data. I make my own chutes, mainly out of (I believe) 1.6 oz silicone-coated ripstop. It's light, packs well, and is nearly zero porosity. I typically make semi-elliptical shapes, with the nominal canopy height one quarter of the diameter, and with a small-ish spill hole. My 36" chute with light shroud lines is 60 grams. That's my usual go-to for 2.5-5 lb rockets. The 30" chute with slightly heavier shroud lines is 45 grams. I could probably shave off 5-10 grams from that with lighter shroud lines. The 30" one would be fine for a 3-lb liftoff weight rocket at sea level, especially if the landing surface was fairly soft. Not sure how it would do at altitude.
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Silicone-coated nylon and ZP nylon aren't the same - the former is (in my experience) made from heavier fabric, plus it has the added weight of the coating. ZP nylon is made (if I remember correctly) by running the nylon through hot rollers. It results in nylon that allows a lot less air through, making a comparable chute of the same size/weight fabric have a higher Cd, with no weight penalty from a coating.
-Kevin
boatgeek
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Not to turn this into a glue thread... This is the stuff I use, actually 1.3 oz silicone impregnated ripstop. I haven't weighed a yard of it to see what the exact weight is, so I don't know how much the silicone adds. It is definitely less porous than standard ripstop, but I don't know exactly how much porosity it has.
Anyway, data indicates a chute can be had for ~35-40 grams for the H record model, maybe even less if you went to an iris type. The altimeter assembly is on the order of 20-30 grams depending on the battery, so a reasonable light chute is about twice the altimeter.
Edit: That’s the weight for a deployment altimeter. Just a recording altimeter would be quite a bit lighter.
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vulpesjr
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Makes sense. With mylar and a mandrel, I would be careful laying down epoxy before sliding the sleeve on as it can make getting the sleeve on cleanly fairly difficult IMO. Using a very low-viscosity resin or a sleeve diameter much larger than the tube should help if you choose to do that in the future.
Edit: I guess you kind of addressed that already but still worth noting
Last year at NSL west i made an attempt at the TRA K altitude record. I flew short of the record by close to 300ft roughly. I ended up at 31,374 ft agl. Might try the K and L record attempts this year if plans to go work out
Neutronium95
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If you still have the paperwork somewhere, you should submit it to the records committee. Curt's record was removed recently because of a lack of GPS data.
What motor did you use? I've considered attempting the K record, but the very poor reliability of the CTI K300 has discouraged any serious attempts on my part.
Not really worried about it. At the time Curts record was what i needed to beat. It was what was listed. Besides. Gives me the chance to fly another great flight. I used a AT K250 with a rocket that was about 24oz everything but motor.
Wow @Conway Stevens !
Once again, there must be some some first-class engineering in your design.
The best I can do in a q&d OR sim with COS parts and without 'cheating' is 1100 grams / 39 oz dry weight
Looking forward to another great flight report sometime after Memorial Day weekend !
-- kjh
In the meantime, it's great to see @JimJarvis50 's K record restored.
RMS or SU?
The latest version is DMS
Gotcha. I have a SU in my shop... Be interesting to compare the results lol
bandman444
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Is there a DMS version? The one I just bought from Aerotech is the LMS version they’ve been making for a long time.
Technically its a LMS. But... outside of the closures you supply everything is disposable single use including the case.
Neutronium95
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I feel like there's a big difference between the weird LMS version of the K250 and regular DMS motors. With a fiberglass motor case, it's super simple to bond the fins directly to the motor, allowing you to do a submin configuration with no added drag from a fin can.
rfjustin
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Correct, current version is LMS, not DMS.
Rocketjunkie
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Note that most of the time the case survives just fine. Then you have a 54/2800 case
bandman444
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So we’ve got a start on the H and I records, let’s start up the J and K records.
This starts with the body and a new process for me to learn: removable mandrels.
Recall that for the H and I, they used a thin wall paper tube and the carbon was laid up directly on top of that. Well, I’ve been reading about an even light way to do it…simply remove the cardboard tube after the carbon layup and have a pure carbon tube. Oh boy if it were just that easy.
On the right is the mandrel for the J and K records.
First, about the mold. We start with a cardboard tube about the right size. I was given two 5” cardboard tubes at LDRS in Wisconsin. (If you are the rocketeer that left a box of these tubes out for free. Or if you are the rocketeer that ran into the swarm and grabbed me two tubes because “you knew I would do something cool with them”, THANK YOU!)
These tubes were great for a lot of reasons, one thing that wasn’t perfect was the diameter. They are 5”, but they are 5” Inner Diameter. And since these are thick tubes (think carpet roll) the OD is a little bigger than I would like, but since the category was really made for 5.5” rockets, a 5.2” tube won’t be a big deal. Next time I would love to get closer to the 5" minimum
The tailcone mold was also 3D printed like it was for the H/I rockets. It wasn’t acetone vapor smoothed as it was going to be wrapped in release film and waxed.
In order to prep the tube a needed to wrap it in a layer of mylar release film. I don't know much about the material I have, but I've used it for vacuum bagged layups in the past.
Started by taping mylar down to the tube with some kapton tape.
After wrapping the whole tube, it is sealed with a single piece of mylar all the way top to bottom.
The tailcone gets a similar treatment with mylar and kapton tape.
After that the mylar was coated in this great smelling paste wax. Did it do anything? Probably not, but I tried.
The first layer was pretty easy to slide on and get aligned.
Thankfully I had some help from a friend during this layup and after the first lay was wet out, A second layer of 8K 8" Carbon sleeve from Soller Composites was added. It was not trivial to slide a second layer over a wetted out layer.
After the second layer was wetted out, things were looking really good.
The heat shrink was added and...well...I still need to get better at this. Lots of little problems with wrinkles, epoxy blobs, tears, seams, etc. Still not convinced this is better than a layer of peel ply and a layer of epoxy to smooth it out.
This starts with the body and a new process for me to learn: removable mandrels.
Recall that for the H and I, they used a thin wall paper tube and the carbon was laid up directly on top of that. Well, I’ve been reading about an even light way to do it…simply remove the cardboard tube after the carbon layup and have a pure carbon tube. Oh boy if it were just that easy.
On the right is the mandrel for the J and K records.
First, about the mold. We start with a cardboard tube about the right size. I was given two 5” cardboard tubes at LDRS in Wisconsin. (If you are the rocketeer that left a box of these tubes out for free. Or if you are the rocketeer that ran into the swarm and grabbed me two tubes because “you knew I would do something cool with them”, THANK YOU!)
These tubes were great for a lot of reasons, one thing that wasn’t perfect was the diameter. They are 5”, but they are 5” Inner Diameter. And since these are thick tubes (think carpet roll) the OD is a little bigger than I would like, but since the category was really made for 5.5” rockets, a 5.2” tube won’t be a big deal. Next time I would love to get closer to the 5" minimum
The tailcone mold was also 3D printed like it was for the H/I rockets. It wasn’t acetone vapor smoothed as it was going to be wrapped in release film and waxed.
In order to prep the tube a needed to wrap it in a layer of mylar release film. I don't know much about the material I have, but I've used it for vacuum bagged layups in the past.
Started by taping mylar down to the tube with some kapton tape.
After wrapping the whole tube, it is sealed with a single piece of mylar all the way top to bottom.
The tailcone gets a similar treatment with mylar and kapton tape.
After that the mylar was coated in this great smelling paste wax. Did it do anything? Probably not, but I tried.
The first layer was pretty easy to slide on and get aligned.
Thankfully I had some help from a friend during this layup and after the first lay was wet out, A second layer of 8K 8" Carbon sleeve from Soller Composites was added. It was not trivial to slide a second layer over a wetted out layer.
After the second layer was wetted out, things were looking really good.
The heat shrink was added and...well...I still need to get better at this. Lots of little problems with wrinkles, epoxy blobs, tears, seams, etc. Still not convinced this is better than a layer of peel ply and a layer of epoxy to smooth it out.
Then I let it cure. A couple days later...
MClark
Well-Known Member
For H I just used the thin cardboard tube.
Nose and tail carbon
Nose and tail carbon
bandman444
Well-Known Member
Turns out, you are totally right. This tube is beefy. Almost 4 pounds. I was originally scared of doing 1 layer, but that is what I will do for the second tube. The most thrust this rocket is designed for is a K250 which has a peak thrust of less than a 100lbs. High performance that doesn’t automatically mean Mach 3+ is new to me. Gotta practice more “finesse”.
Live and learn.
The 8K sleeve was on sale, so I bought a bunch too…
boatgeek
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On the plus side, you now have a really nice tube for whatever 98mm motor you want to use!
MClark
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No, no!
Put a couple more layers on it.
I am looking to do the J record
Put a couple more layers on it.
I am looking to do the J record
