Bryce's Handicap Record Quest: NSL 2024

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bandman444

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I’m excited to share and document the progress and plans for one of my most ambitious projects.

For over a decade I’ve been enthralled with the idea of setting an official altitude record in rocketry. I’ve watched performance titans like Curt von Delius, Adrian Adamson, and Jim Jarvis push the limits of performance to the max. I’ve also been pretty quick to judge my skills as “not good enough” to compete at their level. While many of the records continue to reach higher and higher, the need for perfection (and my lack of ability to reach there) kept them pretty far out of reach.

I had probably been loosely aware with the idea that there might be other record categories, and while the hyper-optimized single-stage commercial category may be above me (literally), perhaps another category would bring lighter and more fun competition.


Now would be a good time to remind you about the categories for Tripoli Altitude records.

Tripoli’s Records Committee (to which I am a member) manages six unique categories, each with their own rules. Four categories require the use of commercial motors. Those would be the single-stage, multi-stage, cluster, and handicap categories. The additional two are research motor focused with an individual as well as a group category. All of the rules can be found HERE. I feel most of the categories are generally self-explanatory, with one exception, Handicapped.



What is the Handicapped record category? (Again, if you want specific details, see THE RULES).

The handicapped records category is a category of records in which the minimum rocket size is specified for each category. For example, you might know that the single-stage commercial H record is currently using the H13ST motor with rockets that are barely longer than the motor and weigh less than 100 grams. In the handicap record, the rocket MUST have at least 3 feet of the length over 3.75” diameter. This means that naturally the altitudes are significantly lower. This allows those who want to compete an opportunity to fly without needing a “black rock” altitude waiver.

Odds are that if you have flown a handful of high power rockets, you have probably flown a rocket that qualifies for the handicap records.

At the moment (March 2024), Tripoli has handicap record categories for each motor size G through O. If you look through the rules and current records, a couple of things jump out at you. First, there are no submissions for the L and N motor categories, that means that any qualifying flight takes it. Second, with the exception of G, H, and O, all of the current records are over 20 years old. Third, I am already the owner of the current O handicap record. Is it a good record? No, it’s silly, but it counts, so I am not going to be building a rocket for the O category. Lastly, while there are nine motor categories, there are only five “rockets” (sets of requirements). Meaning that for example the rules for the H and I are both 3ft long and 3.75” diameter meaning they *could* be the same rocket.

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“Hey Bryce, show us your rockets!!!”


Hold on, hold on, I’ll get there. A few more things.



What are my goals?

I want to define my goals clearly, and I will judge my success based on the following. I will also outline my thought process and justification.

1. Bring more awareness to this underrated record category by sharing my designs, progress, and results publicly.
My main goal is to inspire folks to get out there and have some fun with these categories. I want people to look at my projects and say “I can do that”. If my record attempts inspire a few people to try for these or other Tripoli records, it will be completely worth it.

2. Fly for all needed records in one weekend
Why: Something I have personally struggled a lot with is being efficient with time and project execution. I’ve been able to fly one or two rockets a weekend, but flying seven back to back high power rockets is going to be a new challenge for me with regards to organization, logistics, and preparedness.

3. Set the records at NSL West 2024.
Why: Because I will be there. My local waiver won’t allow for many of these flights. And where better to set altitude records than in Colorado at a launch site over a mile in the sky?

4. I want to set “great” records. Not “excellent” records
Why: You’ll see shortly that I have put a lot of effort into this series of rockets. However, I want there to be room for others to have fun in this category, and my honest hope is that others find wonderful and interesting ways to beat my records. I would not succeed in my primary goal if by doing these projects I "scare" people away. I truly hope that I can do a good attempt at these records, and then other swoop in and earn them after me.

5. Attempt all eight Tripoli High Power Handicap records
Why: Challenge myself across a vast range of rocket sizes and make the goal more difficult


Those are my goals. May 28th we will see how I did.
 
So let’s start talking about these rockets!


Right now I plan to build four distinct rockets. As the H and I rules are the same, likewise J and K, L and M, as well as N and O are the same. That being said, with the exception of N and O, I plan to build each rocket twice. This means I am building* seven complete rockets. My main motivation behind this strategy is twofold. First, it means I can prep each rocket at home and not rely on recycling a rocket after each attempt. I don’t want to run out of time that weekend. Second, it also gives me a redundant rocket for each category. In the unfortunate event of a flight or landing issue, I will have a second rocket capable of competing again in the category.

Each rocket starts from the same set of design principles. These were determined over the course of multiple months of research, calculations, and simulations like OpenRocket.


You want to master Handicap? Here is what you need to know. (Free advice some someone who doesn’t yet hold most of the records)

  1. Mass is your enemy. It might be obvious, but it is clear that in order to win, you must optimize all of your design decisions for lowest weight. Little changes in weight greatly affect your final altitude.
  2. Long burning motors at the top of the impulse class are the best motors to use. I will talk later about what motors to use, but with the possible exception of the J record, longer burning motors win. This is an important guideline to keep in mind. This decision trickles down to a lot of the further guidelines. Long burning motors cause rockets to not go as fast, therefore they experience less drag losses, therefore they experience less aerodynamics loads, therefore they don’t need to be built as strong, therefore your rocket achieves a very lightweight.
  3. Strong aerodynamic choices are imperative. Because of Rule 2, not a single rocket here will even reach supersonic speeds. That means we need to think like a lower speed rocket. My inspiration is the FAI altitude record rockets. These incredible feats of micro-engineering are extremely good case studies to learn from. Tailcones are a must in order to minimize the base drag during ascent. Short, elliptical nosecones are great are minimizing drag without adding needless weight. I found that around 1.3-1.5 length-to-diameter ratios had the right balance of weight and drag. As many of these records will be very subsonic, elliptical does very well, however, some categories get close enough to mach to benefit other nosecone shapes like ogive.
  4. Three fins are better than four. I’m always on team four fin, but the number don’t lie, at these velocities, you are almost always better with three bigger fins than four smaller ones. Keep them light, stiff, and make sure to airfoil them.
  5. When possible, launch from a tower. A classic records tip is flying out of a tower. While the N and O category might not lend itself well, most of the others can take advantage of being flown from a tower. That being said, the drag effect of having rail buttons on these rockets is much less noticeable than in the regular single-stage record category.
Other obvious things not listed are making the rocket diameter as close to the limit as possible. Hobby tubes may be close, but you’ll need to be the judge on whether they are close enough, or if you need something custom/uncommon.


Now that we’ve got defined goals and we’ve spent a couple months researching and planning, I think we are ready to start building! Oh, and we’ve got less than 10 weeks until flying!
 
H and I Handicapped Altitude Records

Requirements: Greater than 3.75” diameter for over 36” in length.

Current records: H motor 4,130ft, I motor 6,355ft

Construction:
I’m starting construction on the smallest rocket first in order to give me the most opportunities to learn on something small and cheap while refining my material choices and manufacturing methods.

Body Tube
I had originally planned on using LOC 4” tube as the main body tube (which is certainly what would have been easiest). However, a little bit of looking around online turned up some “BT-100” tube from Semroc. This paper tube has an inner diameter of 3.702” and importantly an outer diameter of 3.744”. Besides the fact that this tube is under the 3.75” requirement by itself, it is also WAY too thin for a high power flight. This stuff is super crazy thin and light, and will be a perfect canvas for a layer of carbon fiber sleeve. For this design, I will bond the carbon to the body tube versus wrapping it in Mylar and only using it only as a mandrel.
IMG_0647.jpg
H/I record on left, J/K molds on the right​

I’ve never used cloth sleeve before but it promises to be easier than rolling, makes tapers over transitions seamless, and without an axial seam line. I’ve also not used the shrink tube that Soller Composites sells to make finishing and compacting this tube uniform and smooth. I am a bit surprised at the price for it, and its value over just wrapping with peel ply or Mylar will need to pretty high for me to use it again.

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Dry fitting the sleeve over the tubes and tailcone​

The transition was generated for this in order to have a 10deg taper angle, a shoulder to be bonded to the body tube, 2” of straight cylindrical section to make up for the slightly short body tube, and taper completely to a 54mm motor mount. It was printed out of ABS and is approximately .040” thick. A tapered 38mm adapter will be made for the H altitude flight. The tailcone was glued to the aft end of the body tube and then overlayed with carbon fiber sleeve.

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Pre-epoxy, things are ready

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Not perfect, but that heat shrink needs more skill than I've currently got if I want it to lay flat.

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Going from the ~4" down to ~54mm was very challenging

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Sometimes too much heat from the heat gun would open up these seams
IMG_0705.jpg
The surface finish was passable for most of the tube.
The tube/tailcone combo weighs only 341 grams. Well under what I think I will need to beat the H and I records, so I'll call this one good enough. I will probably sand and polish the tube later.

The nosecone will be made using a 3D printed ABS male mold. It was vapor smoothed, covered in partall model release, and then paste wax.
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After using tape and paper to help make a template, I cut out eight fiberglass gores from some scrap 6oz glass I have, each 1/4 of the nosecone.
IMG_0659.jpg
After using some West Systems and the fast curative, I had a nice little nosecone. And at under 35 grams, it is .040" thick and seems strong enough for a couple H and I flights.
IMG_0682.JPG

Next up will be the coupler, and avionics bay. Then I can pick a parachute and size the fins.
 
Watching.... and curious.... :) For the Handicapped Category Classes, M for example, "7.5 inches for at least 8 feet." For clarity sake, that's 8 feet of tube and does not include the nose cone length or tail cone length, correct?

Thanks!
 
Watching.... and curious.... :) For the Handicapped Category Classes, M for example, "7.5 inches for at least 8 feet." For clarity sake, that's 8 feet of tube and does not include the nose cone length or tail cone length, correct?

Thanks!
Great question, it definitely *could* include part of the nosecone and tailcone, but at least 8ft of the rocket must be bigger than 7.5 inch in diameter.

A silly (but relevant) example is the O handicap record is currently held by Project Sasquatch which even though the body tube is only 6ft long, the nosecone is sufficiently long enough that 6ft of the nosecone is greater than 11.5" so combined they meet the requirements for the O record.
 
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Are the rest of the rockets built in the same way with the carbon reinforced cardboard? Or are you planning on using mylar and a mandrel at some point?
 
Are the rest of the rockets built in the same way with the carbon reinforced cardboard? Or are you planning on using mylar and a mandrel at some point?
Great question! Lots of parts of this project is new to me, so for the H and I rocket airframes, you saw that I bonded the carbon directly to the tube without pulling it out.

On the J and K airframes, I chose to remove the cardboard mandrel after carbon application. Lots of pros and cons to each, the main pro for me was that it was a new process and I could learn a lot from it. I'll write a whole post on the process in a little bit.
 
It looks like you laid the sleeve dry without adding any epoxy underneath it? How did you ensure the fabric was fully wetted out?
 
Sometimes too much heat from the heat gun would open up these seams​
Not sure how practical this would be for you now, but I've experimented through that same process to find the smoothest surface finish for wrapped carbon tubes with the least amount of effort. Like you said, using shrink wrap is pretty tedious and looks good when done right, but the results can be inconsistent. Especially as you get into making larger tubes, the slightest mistake with the heat shrink can "compromise" your desired finish for the tube. The resulting work to amend those mistakes ultimately takes longer than the initial process. I used that method on multiple 75mm carbon tubes, but found another method to be much quicker and reliable. Partially inspired by Jim Jarvis btw.

Try wrapping the wet tube in a few layers of peel ply instead of shrink wrap. Once the tube is cured, brush a very thin layer of the same resin onto the outside of the tube. Just enough so that it doesn't run or move around when you rotate the tube. Once that cures, lightly wet sand to the desired finish. I've done this with a few 48"+ long tubes, and the results were perfect every time.
 
This is quite an adventure and a pretty neat goal!

I'll be curious what you're using for recovery, as well - parachutes can be *heavy*.

-Kevin
 
I think you should set the records at a Tripoli launch not a NAR.

I have a rocket that was prepped at BALLS for I record, burned in altimeter in a cluster record rocket. Going to try again this year.

Picture- solid aluminum mold for using LOC tube and a 54mm motor.

IMG_3186.jpeg
 
This is quite an adventure and a pretty neat goal!

I'll be curious what you're using for recovery, as well - parachutes can be *heavy*.

-Kevin

Yes they are.
The parachute is considerably heavier than electronics so I have the chute as for forward as possible. In nose cone if possible.
I have been launching at Black Rock so doing single deployment, I like the Jolly Logic but don’t use on record flights because of weight.
H handicap is really weight critical.


I hold the current H record.
Cardboard airframe tubes. Hand wound carbon nose and tail.

IMG_0583.jpeg
 
Is it safe to assume then that the plan for the Sod Blaster group effort has been scrubbed?
 
Yes they are.
The parachute is considerably heavier than electronics so I have the chute as for forward as possible. In nose cone if possible.
I have been launching at Black Rock so doing single deployment, I like the Jolly Logic but don’t use on record flights because of weight.
H handicap is really weight critical.


I hold the current H record.
Cardboard airframe tubes. Hand wound carbon nose and tail.

View attachment 636608
This may be ignorance from not having tried to optimize on weight, but I've never really thought of thin mil nylon chutes with light shroud lines as being particularly heavy. How heavy is the record rocket, and how much does the chute weigh?

As you did, I think there's a lot of weight savings to be had by sticking with cardboard airframes where possible. For H and I flights with low average thrust, I could imagine getting away with thin wall cardboard.
 
If you can use cardboard, I'm sure you can use balsa and be lighter.
--------
No categories for smaller than G? Is that left to the NAR?
 
Tube is 0.021” thick. Pretty light
I believe the H rocket was 3 lbs on pad.
Before next flight it’s going on a diet.
 
Bryce,

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.

Keeping my fingers crossed for you and following along with great interest.

Steve Kristal
NAR 82815
 
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Tube is 0.021” thick. Pretty light
I believe the H rocket was 3 lbs on pad.
Before next flight it’s going on a diet.
Back of the envelope calculations suggest you'd only save an ounce or two with a balsa body tube, so you have a point. I guess the motor must weigh 300 or 400 grams. Where's the rest of the weight? Don't feel obligated to answer.
 
Weight just adds up. I do have a couple of quick links to remove. Any weight removed I can use a smaller chute.
Nose and tail cones were the first time using a wound technique. Could be lighter.
The tail has to be able to survive a landing, for a record there can be little damage, like a cert flight. I could make fins a lot lighter, would fly fine but not survive a landing.
 
I weighed parts on a spring postage scale. Marginally accurate at low end.
Nose cone just under 2 oz.
Bottom half of airframe, 12 oz.
Payload section tube was damaged and junked. Not included in weight.
So the airframe is about a pound, pretty good for a nearly 4” rocket.
Parachute is buried in box with the others.
 
It looks like you laid the sleeve dry without adding any epoxy underneath it? How did you ensure the fabric was fully wetted out?
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.
 
I have a 7.767" Goblin that has flown in 2 configurations.
Blue Tube main body, PML internals 24 lb. prepped less motor.
Kept zippering that's why the rebuild had a G12 body.
File name Rocket Alt Motor Date Location Comment
Goblin03.pfd Goblin 6350 AMW M1350WW 6-12-10 Orangeburg, SC Onboard video
Goblin05.pfd Goblin 5448 L1100 (75-4800 ex) 7-5-10 Penn Yan, NY
Goblin07.pfd Goblin 5309 AT L952 (98/5120) 9-5-10 Orangeburg, SC
Goblin08.pfd Goblin 7803 M1100 (98/7680 ex) 9-6-10 Orangeburg, SC Main at apogee, 18" zipper onboard video
Goblin09.pfd Goblin 13004 N800 (98/15360 ex) 4-8-11 Price, MD Past trees, 6" zipper, used and needed RDF tracker
Goblin11.pfd Goblin 3551 CTI L935 (54-6GXL) 10-2-11 Orangeburg, SC
Goblin13.pfd Goblin 4815 AT L1300R 10-13-12 Orangeburg, SC Zipper

G12 main body, PML internals 32 lb. on pad less motor.
Goblin16.pf2 Goblin 2 3023 CTI L935 (54-6GXL) 1-9-16 Rembert, SC G10 main body, rest same as first Goblin
Goblin17.pf2 Goblin 2 3956 AT L1390 (75-3G) 5-15-16 Rembert, SC
Goblin18.pf2 Goblin 2 4323 AT L1300 (98-2G) 9-4-16 Rembert, SC
Goblin19.pf2 Goblin 2 4569 AT L2500 (98-2G) 5-7-17 Rembert, SC
Goblin20.pf2 Goblin 2 8782 AT M750 (98-4G moon) 4-28-18 Bayboro, NC

I do have video of most of the flights and the on board when shown. Also have the altimeter files (Strattologger).
This is the rocket. I'm 6'3"
Finished03.JPG
 
This may be ignorance from not having tried to optimize on weight, but I've never really thought of thin mil nylon chutes with light shroud lines as being particularly heavy. How heavy is the record rocket, and how much does the chute weigh?

As you did, I think there's a lot of weight savings to be had by sticking with cardboard airframes where possible. For H and I flights with low average thrust, I could imagine getting away with thin wall cardboard.

"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
 
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.

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
 
Try wrapping the wet tube in a few layers of peel ply instead of shrink wrap. Once the tube is cured, brush a very thin layer of the same resin onto the outside of the tube. Just enough so that it doesn't run or move around when you rotate the tube. Once that cures, lightly wet sand to the desired finish. I've done this with a few 48"+ long tubes, and the results were perfect every time.
Thanks for the suggestion. That is actually how I usually make tubes. I’ve got plenty of peel ply in stock, that I might give it a try. I wanted to give the heat shrink tube a try, but so far it has been a disappointment. I don’t want to give up on it too soon as I understand with any composites fabrication method that there is a learning curve and I’ve got to improve my skills if I want a new skill to succeed. We will see what I choose when making the redundant body to each rocket.
 
This is quite an adventure and a pretty neat goal!

I'll be curious what you're using for recovery, as well - parachutes can be *heavy*.

-Kevin
You bring up a great point Kevin. As I am planning electronics in the nosecone, I am planning the parachutes to be right below the shoulder. My plan right now is to install a thin plate/bulkhead in the body, below the shoulder with enough space for the parachute/nomex/shock cord. This should keep the parachute from sliding down the length of the body tube and allow the parachute mass to contribute the most it could to a CG forward shift.

As to the exact parachutes, I’m not sure today what I will use as my masses are still jumping around. Another consideration is the lower air density of the launch site and how much increase the parachute size in order to land soft enough for good recovery. I love that everything in this rocket is a fun trade off, a larger parachute means a high forward CG, which means less needed fin size, which forces the CG higher.

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.
 
I hold the current H record.
Cardboard airframe tubes. Hand wound carbon nose and tail.

View attachment 636608

Thanks Mark! The H Handicap Record is definitely one of the most competitive record (as is the K). In the record listing it lists a 3 pound launch weight, and that has been my goal to beat. I think I will get there, but we shall see!

Good luck on the I motor flight at BALLS this year! I hope I can set a challenging bar for you to cross, but it looks like you are well on your way with an awesome looking mandrel.

For aluminum mandrels, do you plan to just lube it up and layup on top of it? You mention “hand winding”, do I understand correctly that you are winding tow on the mandrels by hand? That would be really cool to hear more about!
 
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