Highperion - My attempt to break the Tripoli H altitude record

[bad_idea]

He's the one that told me they weren't records-legal. I'd love to see official verbiage on this in the rules.

Interesting. Wonder if his opinion changed in recent months or if the way we worded our questions came across differently. Guess it's worth following up again for anyone who's planning a sub-minimum record attempt. (It's sadly an irrelevant question down here in the thick, low-altitude air of the fields where I fly.)

 

[MClark]

I just spoke to Gerald.
The fins glued to single use motors used to be not allowed for a record. The TRA board reviewed this and instead of rocket needs to be able to be reused it is now rocket must have safe recovery.
Fins glued to DMS, good.

This would allow cover rockets with aerodynamic burn damage.

Mark Clark
TRA Records Commitee

 

[bad_idea]

I just spoke to Gerald.
The fins glued to single use motors used to be not allowed for a record. The TRA board reviewed this and instead of rocket needs to be able to be reused it is now rocket must have safe recovery.
Fins glued to DMS, good.

This would allow cover rockets with aerodynamic burn damage.

Mark Clark
TRA Records Commitee

Thanks for confirming, Mark.

 

[Jeremy Sim]

I just spoke to Gerald.
The fins glued to single use motors used to be not allowed for a record. The TRA board reviewed this and instead of rocket needs to be able to be reused it is now rocket must have safe recovery.
Fins glued to DMS, good.

This would allow cover rockets with aerodynamic burn damage.

Mark Clark
TRA Records Commitee

"Good Recovery" does this mean I can use a streamer for a Record Attempt?

 

[Neutronium95]

"Good Recovery" does this mean I can use a streamer for a Record Attempt?

As long as it brings the rocket down at a safe speed and it lands with no damage, I don't see any reason why a streamer couldn't be used. That said, I doubt it would be the optimal solution. A parachute will produce more drag with the same amount of material.

 

[MClark]

"Good Recovery" does this mean I can use a streamer for a Record Attempt?

You use the quote "Good Recovery". That is not in my post.
It is safe recovery. What would be good for a certification flight.

 

[GrouchoDuke]

I just spoke to Gerald.

Fins glued to DMS, good.

This would allow cover rockets with aerodynamic burn damage.

Thanks for running this down, Mark. it's great to know where the bounds are.

 

[Neutronium95]

Progress is happening on this project. I received 3 more sets of fins from @REK a few days ago, and I finally got around to building a testbed airframe for recovery testing. I've also been working on figuring out how to use a single ematch as a cable cutter for fishing line, to make dual deploy feasible. Now I just need the H14s in my Wildman order, and I'll be in a good position to bring 3 rockets finished and fully prepped to go for the H record at NSL in a bit over a month.

I tried to fly the test rocket this past Saturday at FAR, but ran into too many headaches prepping it. So I'm going to lengthen the nose a bit, and significantly increase the length of the cylindrical section. As I was telling people at FAR, if your design requires the use of specialty nuts because regular 2-56 nuts are too big, you're doing something wrong.

Edit: I just looked back through the thread and saw how I was talking about sacrificing everything on the altar of performance. I might just build one of my 3 motors as a single deploy configuration for NSL, just to see how dang high I can go.

 

[rokit]

Progress is happening on this project. I received 3 more sets of fins from @REK a few days ago, and I finally got around to building a testbed airframe for recovery testing. I've also been working on figuring out how to use a single ematch as a cable cutter for fishing line, to make dual deploy feasible. Now I just need the H14s in my Wildman order, and I'll be in a good position to bring 3 rockets finished and fully prepped to go for the H record at NSL in a bit over a month.

I tried to fly the test rocket this past Saturday at FAR, but ran into too many headaches prepping it. So I'm going to lengthen the nose a bit, and significantly increase the length of the cylindrical section. As I was telling people at FAR, if your design requires the use of specialty nuts because regular 2-56 nuts are too big, you're doing something wrong.

Edit: I just looked back through the thread and saw how I was talking about sacrificing everything on the altar of performance. I might just build one of my 3 motors as a single deploy configuration for NSL, just to see how dang high I can go.

Drill a couple holes opposite each other in the plastic protector on the ematch to pass the line through. If there's any plastic in the line you use the ends may ball up where it melts, so either size the holes appropriately or use line without plastic (like heavy sewing thread). A little hot glue on each end of the protector helps keep it in place on the ematch head.

Bill Inman set a bunch of records way back when using single deploy.

 

[Neutronium95]

Drill a couple holes opposite each other in the plastic protector on the ematch to pass the line through. If there's any plastic in the line you use the ends may ball up where it melts, so either size the holes appropriately or use line without plastic (like heavy sewing thread). A little hot glue on each end of the protector helps keep it in place on the ematch head.

Bill Inman set a bunch of records way back when using single deploy.

That's what I'm looking at doing right now. In my experiments, I've had some success with running the fishing line through the protector alongside the ematch.

Single deploy has worked alright on the previous two flights, but it can easily lead to rockets drifting 5+ miles if there is any wind. I will probably bring options for both single and dual deploy flights at NSL, and make the decision on what to fly based off of the conditions at the launch site.

 

[tfish]

I played around with fishing line, nylon cord and just zip ties along time ago..even with added BP I was not getting clean..melts.
Is the size of line cutters the reason your not using/switching ?

I wonder if an ematch will fit inside a 22 cal?

Good luck ..

Tony

 

[bad_idea]

I wonder if an ematch will fit inside a 22 cal?

I think @rocketace does this, though with a .22 magnum if I remember correctly (which it's very possible I don't).

 

[SolarYellow]

Why not cotton thread?

 

[SolarYellow]

I think @rocketace does this, though with a .22 magnum if I remember correctly (which it's very possible I don't).

Maybe a .22LR inside a .22WMR?

 

[rocketace]

I think @rocketace does this, though with a .22 magnum if I remember correctly (which it's very possible I don't).

Yes, I tried a regular 22LR, but it was just too short. The .22 mag was just about perfect. Here was my set up.
https://www.rocketryforum.com/threa...-stage-54mm-min-diameter.165955/#post-2343825

Only difference now is that I also use a small amount of sticky tack on the inside as well to help seal anything from blowing out the back.

 

[lr64]

Interesting project.

Looking at this picture:

I wonder if there wouldn't be a bit less drag if you extended the fillets all the way back to the end of the boat tail. Look at wing fillets. I am just an armchair aerodynamicist, though, so you needn't take me to seriously. It may be that separation is not actually happening. A further guess is that if you used a thin, laminar foil for the fins, you'd cut drag. Probably one of the ones with the maximum thickness further back, since you'll be at Mach 0.9. If you cared to, I would guess that NASA's NTRS server has papers about this sort of thing. You'd have to do a really good job of shaping them, but airfoils with extended laminar flow can have dramatically less drag. Whether this can be done all the way up to Mach 0.9 is another question.

If I was in a hurry to shape something to make it as smooth as possible, I'd probably use auto body spot putty. It sands very nicely, dries pretty fast, etc. I've seen it used for wind tunnel models. If it was me, I probably wouldn't bother with paint, which would be just another way to introduce waves in the surface that initiate turbulent flow sooner.

If the motor provides more than adequate initial acceleration off the pad, you might look into extending burn time by lowering the burn rate. It's my understanding that some propellants are sensitive to the initial temperature. Perhaps a motor that was refrigerated until the last moment would reach a higher altitude. I'm not suggesting that you launch the rocket from a bucket of liquid nitrogen, though. ;-)

 

[DabCat]

I played around with fishing line, nylon cord and just zip ties along time ago..even with added BP I was not getting clean..melts.
Is the size of line cutters the reason your not using/switching ?

I wonder if an ematch will fit inside a 22 cal?

Good luck ..

Tony

I made a bunch of cable cutters from 22LR shells. I've had a 100% success rate over about 15 flights so far. Sometimes you lose the cutter, but I've never had a chute not release on time. I use a single strand of Chinese ematch wire for the cable and mjg standard ematches in the cutter. 3d printed cap and I just fill with powder until the ematch head is nearly covered.

 

[Neutronium95]

I played around with fishing line, nylon cord and just zip ties along time ago..even with added BP I was not getting clean..melts.
Is the size of line cutters the reason your not using/switching ?

I wonder if an ematch will fit inside a 22 cal?

Good luck ..

Tony

I've seen line cutters based off of 22 casings that seemed to work alright. My main concern is packing volume. My nosecone is extremely tight right now, and if I can make a workable solution with just the ematch shroud I'd prefer that.

I'm also a bit nervous about relying on a line cutter. The mylar parachute I'm using seems quite content to stay rolled up, and I don't know whether or not it will open reliably. I'm thinking about maybe using a small piece of 18mm tube attached to the shock cord as a parachute cannon. Or just going back to main at apogee, just with a smaller parachute to reduce drift. I'll have a better idea about what approach to take after flying the recovery system a few times this weekend.

I wonder if there wouldn't be a bit less drag if you extended the fillets all the way back to the end of the boat tail. Look at wing fillets. I am just an armchair aerodynamicist, though, so you needn't take me to seriously. It may be that separation is not actually happening. A further guess is that if you used a thin, laminar foil for the fins, you'd cut drag. Probably one of the ones with the maximum thickness further back, since you'll be at Mach 0.9. If you cared to, I would guess that NASA's NTRS server has papers about this sort of thing. You'd have to do a really good job of shaping them, but airfoils with extended laminar flow can have dramatically less drag. Whether this can be done all the way up to Mach 0.9 is another question.

If I was in a hurry to shape something to make it as smooth as possible, I'd probably use auto body spot putty. It sands very nicely, dries pretty fast, etc. I've seen it used for wind tunnel models. If it was me, I probably wouldn't bother with paint, which would be just another way to introduce waves in the surface that initiate turbulent flow sooner.

If the motor provides more than adequate initial acceleration off the pad, you might look into extending burn time by lowering the burn rate. It's my understanding that some propellants are sensitive to the initial temperature. Perhaps a motor that was refrigerated until the last moment would reach a higher altitude. I'm not suggesting that you launch the rocket from a bucket of liquid nitrogen, though. ;-)

I can't really think of a way to cleanly extend the fillets further back. My current method is to use a small ball on a stick, which allows me to cleanly wrap them around the leading and trailing edges of the fins.

Airfoiling the fins would be nice, but with the thickness of material I'm working with it would be very impractical. The fins are around 1mm thick, and right now I think a thinner fin that's just a beveled flat plate is likely to have less drag than a thicker airfoiled fin. I am looking at doing proper biconvex airfoiled fins on my M record project, since the fins have a lot more meat to work with, and I'm getting the fin can printed out of Aluminum so I don't have any manufacturing concerns.

Both of the previous builds ended up getting rushed across the finish line at the last minute, leaving minimal time for finishing work. I used proline expoxy to fill the weave of the nosecone, and that worked great. Some friends of mine think it's a relabeled tooling gel coat, and from how nicely it brushes on and sands, I'm inclined to believe them. My plan for finishing the rockets for NSL is to get them nice and smooth, then coat in 2k clear coat and polish.

I have considered experimenting with chilled motors to see what the effect on burn time would be, but never got around to it. Who knows, I might just leave one of the motors in the cooler overnight at NSL.

In other news I printed new avbay parts and laid up a new nosecone with the blunter form. Hopefully this leads to less frustration and greater ease of prep.

 

[SolarYellow]

Airfoiling the fins would be nice, but with the thickness of material I'm working with it would be very impractical. The fins are around 1mm thick, and right now I think a thinner fin that's just a beveled flat plate is likely to have less drag than a thicker airfoiled fin. I am looking at doing proper biconvex airfoiled fins on my M record project, since the fins have a lot more meat to work with, and I'm getting the fin can printed out of Aluminum so I don't have any manufacturing concerns.

I was looking at some old aero papers last week that indicated drag on double-wedge fins is considerably lower at supersonic speed than on biconvex. Don't remember where I saw that.

 

[lr64]

I was looking at some old aero papers last week that indicated drag on double-wedge fins is considerably lower at supersonic speed than on biconvex. Don't remember where I saw that.

Yes, but isn't this rocket transsonic?

 

[Neutronium95]

The new nosecone is off of the plug, and the avbay parts needes to mount it are printed.

I had a hell of a time getting it off of the mold. This was the first time I used this method to make a nosecone with a significant straight section. Normally if there is no straight section, once you shift the plug a fraction of an inch back, the entire nose releases. I also didn't use my usual mold release, since I've had issues getting condoms to conform to 29mm molds before. I think the unlubricated balloon I ended up using added a lot of friction to the system.

Anyways, here's a comparison between the new, blunter nose and the old nose.

 

[Neutronium95]

The new nosecone shape worked great. Everything fit much more easily than before. Unfortunately, I ran into some issues on the recovery test flight. The shock cord snapped just above the loop for the parachute, so the nose was lost. Then the parachute never opened, despite my jury rigged line cutter working. Fortunately, despite lake staking, the bulkhead Blue Raven is intact, and the tracker antenna is replaceable.



My takeaway is that trying to do dual deploy in this tiny amount of space is just a poor idea. I actually did some descent rate calculations, and it looks like I can go to a 9" nylon parachute to get a faster descent rate and a parachute that's a bit more robust than the mylar. Ultimately, this test flight was useful, but it's still a bummer that recovery didn't work on it. Also, my 3D printed scoops worked great for measuring the charge size. Trying to precisely weigh out 0.2g of black powder has been a challenge in the past.

 

[Buckeye]

I would agree. Single deploy is the way to go.

Not sure if you know about these scoops, but they are very handy and inexpensive. Smallest size is 0.3 gram. Close enough.

https://www.amazon.com/LEE-PRECISION-90100-Powder-Measure/dp/B000N8OIE8/ref=sr_1_2?crid=2MUS3KYWQVGLX&dib=eyJ2IjoiMSJ9.zEo81zcbykkAOWvtd2KX1cs8nZfApyvmIx1NqAmIpNqYi2vcRn_ADSNZP2wWWKiit92rFFhlxi0RuCYgqXGdhWwx2rN6oji1SPy0U5P77pmDO6c5vdvnh7__JDDw8LNWX5zqNJz0k5IZMH5yyNmFdhejqpZEofjUk1XXZ8ZawrIZCfgZBrvuF8qkFAZovf9c26BAjpGbTJYCUP7rjzYe-B0nUr5y1y51qSY54vT_Y1Y.a_425sppMajzhcULqIdWTU81yEq1_foAFbHK0mXzl0k&dib_tag=se&keywords=lee+powder+measure+scoops&qid=1713183346&sprefix=lee+powder+measure+scoops,aps,162&sr=8-2

 

[Neutronium95]

I would agree. Single deploy is the way to go.

Not sure if you know about these scoops, but they are very handy and inexpensive. Smallest size is 0.3 gram. Close enough.

https://www.amazon.com/LEE-PRECISION-90100-Powder-Measure/dp/B000N8OIE8/ref=sr_1_2?crid=2MUS3KYWQVGLX&dib=eyJ2IjoiMSJ9.zEo81zcbykkAOWvtd2KX1cs8nZfApyvmIx1NqAmIpNqYi2vcRn_ADSNZP2wWWKiit92rFFhlxi0RuCYgqXGdhWwx2rN6oji1SPy0U5P77pmDO6c5vdvnh7__JDDw8LNWX5zqNJz0k5IZMH5yyNmFdhejqpZEofjUk1XXZ8ZawrIZCfgZBrvuF8qkFAZovf9c26BAjpGbTJYCUP7rjzYe-B0nUr5y1y51qSY54vT_Y1Y.a_425sppMajzhcULqIdWTU81yEq1_foAFbHK0mXzl0k&dib_tag=se&keywords=lee+powder+measure+scoops&qid=1713183346&sprefix=lee+powder+measure+scoops,aps,162&sr=8-2

I've seen those before, but I wanted more size options, so I designed my own that I can 3D print. The smallest one in that set is 0.3 cc, while 0.2cc ended up being too much.