tripoli H altitude record

Holy smokes, how is 14k on an H even possible? Is Adrian Adamson on here, or anyone have any additional detail about that rocket? I imagine there has to be some kind of clever trick to that flight, given how much it smashed the previous record. Also the H160 listed does not even seem like one of the more powerful or longer burning options.

I think you looked at the Loki H160 which is a 38mm 81.3% H with a 1.5s burn, the CTI H160 is a 29mm 97.4% H with a 1.9s burn. So it's a 29mm rocket with a full H. Also I notice that the current record is in Highlands Ranch, CO which is at 5700ft above see level, in TN with an elevation around 1100ft. The higher elevation would have lower atmospheric pressure and less drag.

watermelonman said:

Holy smokes, how is 14k on an H even possible? Is Adrian Adamson on here, or anyone have any additional detail about that rocket? I imagine there has to be some kind of clever trick to that flight, given how much it smashed the previous record. Also the H160 listed does not even seem like one of the more powerful or longer burning options.

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Adrian is the maker of the Raven. He made a bunch of absolutely teensy tiny thin-walled carbon fiber rockets in various sizes that have barely enough extra space for recovery, and flew and reflew them to optimize the weight for max altitude.

Minimum drag + optimal weight, and you have yourself a record.

The reason the current I record (held by myself) isn't nearly so extreme is because the rocket was not optimized for altitude (overly large fins, blunt nose, lighter than optimal mass), the motor underperformed (burned too quickly), and it was flown on a windy day which caused it to weathercock strongly (because of the large fins). I took the record because I could.

And then you have to recover the thing. Likely have to leave out a tracker due to the weight and hope for the best. Kurt

Ravenex said:

I think you looked at the Loki H160 which is a 38mm 81.3% H with a 1.5s burn, the CTI H160 is a 29mm 97.4% H with a 1.9s burn. So it's a 29mm rocket with a full H. Also I notice that the current record is in Highlands Ranch, CO which is at 5700ft above see level, in TN with an elevation around 1100ft. The higher elevation would have lower atmospheric pressure and less drag.

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Oh I was looking at Cesaroni, and I saw there was a 315ns version compared to 312ns for the H160. Meanwhile there are definitely higher max thrust options. I suppose what I was getting at is that there had to be some aspect of that flight that was at some extreme or utilized some clever trick. Sounds like not, but rather it was crafted and tuned to near perfection. Hah, I suppose that is part of why altitude records for a smaller motor do not compete with a larger, even when the smaller is greater like H verses I here or N verses O. Also, as you point out I am sure the site elevation was a factor.

CarVac said:

Adrian is the maker of the Raven. He made a bunch of absolutely teensy tiny thin-walled carbon fiber rockets in various sizes that have barely enough extra space for recovery, and flew and reflew them to optimize the weight for max altitude.

Minimum drag + optimal weight, and you have yourself a record.

The reason the current I record (held by myself) isn't nearly so extreme is because the rocket was not optimized for altitude (overly large fins, blunt nose, lighter than optimal mass), the motor underperformed (burned too quickly), and it was flown on a windy day which caused it to weathercock strongly (because of the large fins). I took the record because I could.

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Awesome and congratulations! It sounds fun. Maybe I will give one of them a shot some day, though probably not that H as it looks so intimidating!

CarVac said:

Minimum drag + optimal weight, and you have yourself a record.

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Optimal weght I would think to be minimal weight. I dont think you could make a rocket to minimum weight to be to optimal.

g zilla said:

Optimal weght I would think to be minimal weight. I dont think you could make a rocket to minimum weight to be to optimal.

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The optimal weight is the weight that gives the best ballistic coefficient results with the drag of the model and the motor chosen. It will not be the minimal weight.

Somewhere in the range above G motors it is possible to build a rocket too light to achieve maximum altitude. Below G, motors already exceed optimal weight. There is a trade off between low weight during propellant burn and coasting. A lighter rocket won't coast as far as a heavier rocket at a given burn out velocity. It's particularly tricky as velocity approaches Mach. The curves of boost phase vs coast phase are a bit like the torque and horsepower curves of internal combustion engines without the fixed point crossover effect at 6250 RPM.

g zilla said:

Optimal weght I would think to be minimal weight. I dont think you could make a rocket to minimum weight to be to optimal.

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g zilla said:

Optimal weght I would think to be minimal weight. I dont think you could make a rocket to minimum weight to be to optimal.

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tab28682 said:

The optimal weight is the weight that gives the best ballistic coefficient results with the drag of the model and the motor chosen. It will not be the minimal weight.

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Peter Olivola said:

Somewhere in the range above G motors it is possible to build a rocket too light to achieve maximum altitude. Below G, motors already exceed optimal weight. There is a trade off between low weight during propellant burn and coasting. A lighter rocket won't coast as far as a heavier rocket at a given burn out velocity. It's particularly tricky as velocity approaches Mach. The curves of boost phase vs coast phase are a bit like the torque and horsepower curves of internal combustion engines without the fixed point crossover effect at 6250 RPM.

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Peter is correct. Small motors are above their optimal mass for any possible rocket aerodynamics. Mid-sized motors from G through I ish have an optimal weight which is above the motor mass.

When you get into the big guys, K and above, the altitudes are so high that the rocket punches into the thinner atmosphere under boost and you don't care as much about the ballistic coefficient anymore, rather you want maximum velocity out of a given motor (slower burn still is better).

g zilla said:

Optimal weght I would think to be minimal weight. I dont think you could make a rocket to minimum weight to be to optimal.

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Give it a shot! Open up a simulator, scratch out a minimal design for an F-I motor, then try sliding the mass override for your nose cone. OpenRocket I think will even show apogee realtime during that adjustment. Also consider the relatively tiny boost phase in comparison to the gliding ascent for these birds, and how mass plays into force. Once you drop power, having more mass can be a benefit.

Another way to think of it - wad up some paper to the same size as a baseball and throw it as hard as you can. Now throw a baseball a hard as you can. Which went further?

matthew said:

Another way to think of it - wad up some paper to the same size as a baseball and throw it as hard as you can. Now throw a baseball a hard as you can. Which went further?

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That's a complicated analogy, because the impulse you can impart to the projectile varies based on the weight.

Actually, Highlands Ranch is where Adrian used to live, not where the flight happened. If he launched that one with Tripoli Colorado, it would have been in South Park, which is above 9000' elevation. If that flight was with NCR, it would have been around 5000' elevation. Bet it was the 9k site.
-Ken

The concept of crumpling up some paper and trying to throw it as far as you can throw a baseball is complicated? Really? I guess I must be a genius.

matthew said:

The concept of crumpling up some paper and trying to throw it as far as you can throw a baseball is complicated? Really? I guess I must be a genius.

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The analogy is complicated, not the concept.

matthew said:

Another way to think of it - wad up some paper to the same size as a baseball and throw it as hard as you can. Now throw a baseball a hard as you can. Which went further?

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Yeah but a baseball isnt shaped like a toothpick

Neither is a baseball sized wad of paper.

g zilla said:

Yeah but a baseball isnt shaped like a toothpick

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