bandman444
Well-Known Member
No! Shhhhh. That’s a secret still. (That project is for a completely different Tripoli Record category!)Is it safe to assume then that the plan for the Sod Blaster group effort has been scrubbed?
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No! Shhhhh. That’s a secret still. (That project is for a completely different Tripoli Record category!)Is it safe to assume then that the plan for the Sod Blaster group effort has been scrubbed?
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.No categories for smaller than G? Is that left to the NAR?
I am generally a fan of the Top Flight Thin Mill chutes for their packing volume and cost efficiency. But I’ve not picked what I need yet.
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)My daughter and I have set quite a few NAR altitude records and just last month we set two FAI World Altitude records. Your plan of flying at NSL West is perfect. Field is gigantic, group running that launch is really welcoming, and at ~7000 feet an absolutely fantastic site for altitude attempts.
Really fun to see you trying this and your approach is sound. Wishing you the best of luck on all the designs and flights. If you think my low power insights (yes, I hold the 1/8A altimeter altitude record, LOL) can be of any help don't hesitate to reach out.
Final thought. Although I've never attempted any of them I absolutely love the way Tripoli does altitude records. Really well thought out categories, love the motor-specific records, and the online record site is really fun to read through. As someone who spends quite a bit of time trying to improve organized rocketry, thank you for volunteering your time to be on the Tripoli Records Committee.
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.Does it have to land fins down?
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.One possible approach is to brush on a very thin bit of epoxy onto the tube, then let it set to the green stage. Put your sock over that, and apply enough epoxy to wet out the cloth.
We used an approach along those lines when we built the Delta and Redstone, to help reduce the amount of epoxy that soaked into the tubes.
-Kevin
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.I guess I’m not ever “sure” that I’ve wetted out completely, but getting the sleeve onto a pre-epoxied pour out cardboard mandrel sounded really awful. I use a pretty hands-on laminating technique (with gloves of course) so I’m pretty happy with how much epoxy I am able to massage into the tube after the initial wet out. The fact that the shrink tube also squeezes out a bunch of extra epoxy also makes me think that things aren’t really too dry under there.
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."Thin mil" is a term that seems to occur in rocketry, but doesn't really mean a lot, and it's not just fabric weight that matters. I can have a parachute made of 1.1oz regular nylon or I can have one made of 1.1oz ZP (zero porosity) nylon. The ZP chute can be smaller, because less air goes through the fabric, resulting in higher drag.
When you're going for altitude records, little things start to matter, and every bit of weight you can shave off makes a difference.
-Kevin
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.
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.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
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.I guess I’m not ever “sure” that I’ve wetted out completely, but getting the sleeve onto a pre-epoxied pour out cardboard mandrel sounded really awful. I use a pretty hands-on laminating technique (with gloves of course) so I’m pretty happy with how much epoxy I am able to massage into the tube after the initial wet out. The fact that the shrink tube also squeezes out a bunch of extra epoxy also makes me think that things aren’t really too dry under there.
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.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
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.
Wow @Conway Stevens !I used a AT K250 with a rocket that was about 24oz everything but motor.
In the meantime, it's great to see @JimJarvis50 's K record restored.Looking forward to another great flight report sometime after Memorial Day weekend !
RMS or SU?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.
The latest version is DMSRMS or SU?
Gotcha. I have a SU in my shop... Be interesting to compare the results lolThe latest version is DMS
Is there a DMS version? The one I just bought from Aerotech is the LMS version they’ve been making for a long time.The latest version is DMS
Technically its a LMS. But... outside of the closures you supply everything is disposable single use including the case.Is there a DMS version? The one I just bought from Aerotech is the LMS version they’ve been making for a long time.
Correct, current version is LMS, not DMS.Is there a DMS version? The one I just bought from Aerotech is the LMS version they’ve been making for a long time.
Note that most of the time the case survives just fine. Then you have a 54/2800 caseTechnically its a LMS. But... outside of the closures you supply everything is disposable single use including the case.
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”.2 layers of 8K seems pretty heavy. What's the weigh per foot compared with 5.38" heavy wall cardboard? I've flown the latter on an L1000 with no issues, so I would think it would be fine for J and K flights.
On the plus side, you now have a really nice tube for whatever 98mm motor you want to use!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…
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