mannyskid
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- Feb 2, 2011
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I want to start off by saying that my first year at college has been going decently well so far and I think I can start thinking seriously about this project and how I am going to go about it.
I am planning on building a 75mm minimum diameter rocket to fly at Black Rock sometime next summer, most likely at Aeronaut in August. I have done 75 mm MD successfully in the past before but not like this. The main goal of this project is that I want to make an attempt at breaking the Tripoli commercial M altitude record with a CTI 9977-M2245 Imax. This is the end goal, and there will be a few steps along the way of accomplishing that goal:
The first being that I have to work out a recovery system that I want to use and am comfortable with. I have tried tethers, line cutters and all that in the past. The main issue that I have with those types of systems is that my payload sections are always cluttered with wires and shock cord tangled in a ball by the time I'm done. That's why I am going to be building two rockets for this project. The first rocket is going to be very average hobby grade construction (FW fiberglass and west systems). I want to fly this rocket a few times to allow me to figure out how I want to work the recovery system. I may go with a line cutter, or I may go with a short main parachute bay; that depends of the results of the first few flights. I would also like to fly this rocket to a decently high altitude, preferably above 25,000'. My current plan at this time is to fly it on a CTI M2250 at Kloudburst. I'm not too concerned with this flight as I have done with flight combination with lesser construction methods and kept the vehicle together.
The second being that I have to keep this rocket together at speeds in excess of M3. This is the spot that I have had issue with in the past. Some of you may recall the two N motor rockets that I flew earlier this year that both shredded.
https://www.rocketryforum.com/showt...er-rocket-N3301-at-Kloudburst&highlight=N3301
https://www.rocketryforum.com/showt...osition-98mm-Minimum-Diameter&highlight=N3301
A major issue that was brought up was that the composite materials that I was using were not up to the task. I will have to admit, both of these rockets were built using very average hobby rocket techniques. That is going to change with this rocket. I want to use the best composite materials that I can get my hands on. Vacuum bagged carbon tubes using Aeropoxy, Cotronics Duralco 4461 for tip to tip, thick carbon plate fins (3/16" or 1/4"), and an improved nose cone. A major issue that has also been brought up is dynamic stability at high mach. From what I have both read and seen in the real world, it seems as though a low aspect ratio conical nose cone will be the best at high mach. There is one thing that I am confused on, why is that? Somebody correct me if I'm wrong, but Center of Pressure moves forward because of increased drag on the nose cone compared to the fins at high mach, so why wouldn't a high aspect ratio cone work better? This is an issue that I am going to look into. When I get back to campus, I am going to go straight to the library and see if I can find an answer. There are plenty of books on aerodynamics, many of which were written by Theodore Von Karman. If anyone has any insight on this please share. Also, I am working a 54mm MD though the school, and one of the seniors that I am working with is going to show the rest of us (well, there's only three people on the project) how to use Star CCM which apparently can determine dynamic stability. So maybe we will be able to run our own analysis on this.
Just from some very preliminary RasAero/OpenRocket simulations that I have run, I am thinking of going with a very ARCAS style rocket, with four fins. The design is still in the woodworks and nothing is finalized as of yet.
The last thing that I want to talk about in regards to the actual rocket is the name. The reason that I chose the name "Torn Between Scylla and Charybdis" is because of the real life implications surrounding this mythological tale. In The Odyssey, Odysseus is forced to chose which monster to confront, either Scylla or Charybdis. In the past, I have chosen the path of Charybdis that led to my ultimate doom. This time, I am going to choose Scylla possibly avoiding total disaster.
This time, I am going to be much more open to input given on this project because frankly, I'm going to need all of the help I can get! Also, this is going to be a very slow moving thread so don't expect too much action.
Manny
I am planning on building a 75mm minimum diameter rocket to fly at Black Rock sometime next summer, most likely at Aeronaut in August. I have done 75 mm MD successfully in the past before but not like this. The main goal of this project is that I want to make an attempt at breaking the Tripoli commercial M altitude record with a CTI 9977-M2245 Imax. This is the end goal, and there will be a few steps along the way of accomplishing that goal:
The first being that I have to work out a recovery system that I want to use and am comfortable with. I have tried tethers, line cutters and all that in the past. The main issue that I have with those types of systems is that my payload sections are always cluttered with wires and shock cord tangled in a ball by the time I'm done. That's why I am going to be building two rockets for this project. The first rocket is going to be very average hobby grade construction (FW fiberglass and west systems). I want to fly this rocket a few times to allow me to figure out how I want to work the recovery system. I may go with a line cutter, or I may go with a short main parachute bay; that depends of the results of the first few flights. I would also like to fly this rocket to a decently high altitude, preferably above 25,000'. My current plan at this time is to fly it on a CTI M2250 at Kloudburst. I'm not too concerned with this flight as I have done with flight combination with lesser construction methods and kept the vehicle together.
The second being that I have to keep this rocket together at speeds in excess of M3. This is the spot that I have had issue with in the past. Some of you may recall the two N motor rockets that I flew earlier this year that both shredded.
https://www.rocketryforum.com/showt...er-rocket-N3301-at-Kloudburst&highlight=N3301
https://www.rocketryforum.com/showt...osition-98mm-Minimum-Diameter&highlight=N3301
A major issue that was brought up was that the composite materials that I was using were not up to the task. I will have to admit, both of these rockets were built using very average hobby rocket techniques. That is going to change with this rocket. I want to use the best composite materials that I can get my hands on. Vacuum bagged carbon tubes using Aeropoxy, Cotronics Duralco 4461 for tip to tip, thick carbon plate fins (3/16" or 1/4"), and an improved nose cone. A major issue that has also been brought up is dynamic stability at high mach. From what I have both read and seen in the real world, it seems as though a low aspect ratio conical nose cone will be the best at high mach. There is one thing that I am confused on, why is that? Somebody correct me if I'm wrong, but Center of Pressure moves forward because of increased drag on the nose cone compared to the fins at high mach, so why wouldn't a high aspect ratio cone work better? This is an issue that I am going to look into. When I get back to campus, I am going to go straight to the library and see if I can find an answer. There are plenty of books on aerodynamics, many of which were written by Theodore Von Karman. If anyone has any insight on this please share. Also, I am working a 54mm MD though the school, and one of the seniors that I am working with is going to show the rest of us (well, there's only three people on the project) how to use Star CCM which apparently can determine dynamic stability. So maybe we will be able to run our own analysis on this.
Just from some very preliminary RasAero/OpenRocket simulations that I have run, I am thinking of going with a very ARCAS style rocket, with four fins. The design is still in the woodworks and nothing is finalized as of yet.
The last thing that I want to talk about in regards to the actual rocket is the name. The reason that I chose the name "Torn Between Scylla and Charybdis" is because of the real life implications surrounding this mythological tale. In The Odyssey, Odysseus is forced to chose which monster to confront, either Scylla or Charybdis. In the past, I have chosen the path of Charybdis that led to my ultimate doom. This time, I am going to choose Scylla possibly avoiding total disaster.
This time, I am going to be much more open to input given on this project because frankly, I'm going to need all of the help I can get! Also, this is going to be a very slow moving thread so don't expect too much action.
Manny
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