What Body Tube Fits A 6'' Parachute?

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Looking briefly at the pdf you provided, it looks like you are supposed to DESIGN and build a rocket for competition, not use an existing kit.
Assuming you are entering only the chute duration competition, it must be at least 12" long.
So I would go with a 12" long BT-20 size tube and elliptical fins. This will give you the least weight and maximum altitude for longest duration. Plus, I don't think a 6" chute will fit inside a BT-5 tube.
You might want to consider cutting the launch lug at an angle for less drag. Might add a few millimeters to your apogee.
Also pay attention to the finish of your rocket. A smooth clean finish will minimize drag and maximize altitude. Also round your fins' leading edges and taper your trailing edges.
Doesn't seem like tower or piston launchers are allowed, or fly away rail guides and pop lugs.
But if they are they may add a little to your altitude.
Laters.
 
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Amendment:
The rules say 1/2A motor but doesn't say whether it's an 18 or 13mm motor. I was able to squeeze my 6" parachute into a bt-5 tube. So I would go with a bt-5 tube, and a total length (tube and nose cone) of 12". Fold your chute lengthwise instead of burrito fashion. This all depends of course on whether mini motors are allowed. This should give you the lightest rocket with max alt. and duration.
 
kuririn said:
Looking briefly at the pdf you provided, it looks like you are supposed to DESIGN and build a rocket for competition, not use an existing kit.
Assuming you are entering only the chute duration competition, it must be at least 12" long.
So I would go with a 12" long BT-20 size tube and elliptical fins. This will give you the least weight and maximum altitude for longest duration. Plus, I don't think a 6" chute will fit inside a BT-5 tube.
You might want to consider cutting the launch lug at an angle for less drag. Might add a few millimeters to your apogee.
Also pay attention to the finish of your rocket. A smooth clean finish will minimize drag and maximize altitude. Also round your fins' leading edges and taper your trailing edges.
Doesn't seem like tower or piston launchers are allowed, or fly away rail guides and pop lugs.
But if they are they may add a little to your altitude.
Laters.
Click to expand...
On the contrary, we have been using Alpha and Viking kits for the last 6 comps including a later version of this Competition back in 2016.
 
Okay, this raises more questions than answers.
Are all the teams using Alphas and Vikings?
If so, wouldn't the duration time be about the same for all teams, since they are using THE SAME ROCKET?
 
kuririn said:
Okay, this raises more questions than answers.
Are all the teams using Alphas and Vikings?
If so, wouldn't the duration time be about the same for all teams, since they are using THE SAME ROCKET?
Click to expand...
Not entirely, some rockets that are made can be 12" in height but can be heavier or lighter if the team chooses to add balsa fins or cardboard fins, or plastic fins or plexiglass fins. Also teams may add weight in the nose cone. Additional fins may be added as well. Additionally a variable, such as wind and which direction it is blowing also causes teams to shot in various degrees some 90 other 65 or in another direction entirely.
 
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a 12" parachute will not function correctly if put inside a BT-20, but a 6'' will, I am wondering if I used a 6" parachute will it be able to properly recover a rocket made from a BT-50 hence a (alpha)?
 
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Personally I would never fly an Alpha on less than a 12 inch chute. With a 6 inch if it lands on any thing but grass you are looking at landing damage.
 
You've got 12in of tube less the sum of motor and shoulder. Plenty of room for a 6in in bt5. Side attach part way between CG & CP.

Study the ASP Thermal Seeker 13 and ask yourself why they made those choices.
 
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Matt_The_RocketMan said:
I would like to know if an alpha, wizard rocket can comply with 6 in parachutes.
Body tube wise would be nice to know.....
Click to expand...

Take a trip back in time and build a "Javelin" or "Super Flea" . . .

https://www.spacemodeling.org/jimz/est0815.htm

https://www.rocketryforum.com/threads/estes-javelin-flea-build.11534/

Dave F.

DSC_0009.jpg
 
If you are required to use either the Alpha or the Viking kit, pick the one with the smallest tube diameter and cut it down so the rocket is 12” tall. If you can choose another kit, get a minimum diameter one like the Wizard. Also cut back the back swept fins to more of a clipped delta and stick with balsa. You’ll want to confirm fin size and shape in Rocksim or OpenRocket. Round the leading edge and taper the trailing edge, taking care to keep them even. Take care with your fin alignment when you glue them on and give them nice fillets. Add a minimum amount of paint (one of the few times I’d recommend the Paint+Primer products with no primer).

That will get you maximum altitude. Can you choose your delays? If so, use your sim to determine what’s closest to apogee.
 
Ookay. I think I'm finally starting to wrap my head around this competition. By standardizing the recovery to the dinkiest hardware possible, the flight time will be a reflection of design and building technique for optimized flight characteristics during ascent. All the duration competitions I've seen involved using the biggest streamer or parachute one can fit into a rocket of a given set of dimensions on a specific motor. With those competitions, optimizing a rocket for maximum altitude is a factor, but most of the design focuses on slowing the rocket to a crawl on descent. This one appears to be essentially the opposite with the same goal of maximizing airtime.
 
boatgeek said:
If you are required to use either the Alpha or the Viking kit, pick the one with the smallest tube diameter and cut it down so the rocket is 12” tall. If you can choose another kit, get a minimum diameter one like the Wizard. Also cut back the back swept fins to more of a clipped delta and stick with balsa. You’ll want to confirm fin size and shape in Rocksim or OpenRocket. Round the leading edge and taper the trailing edge, taking care to keep them even. Take care with your fin alignment when you glue them on and give them nice fillets. Add a minimum amount of paint (one of the few times I’d recommend the Paint+Primer products with no primer).

That will get you maximum altitude. Can you choose your delays? If so, use your sim to determine what’s closest to apogee.
Click to expand...
Yes delays can be chosen, usually delays with longer time spans work the best for landing the closest to the target, usually we use A8-3 for 150 yrds and B6-4 for our 250 yrds. We also weight our rockets with plexy fins + glue in the nosecone + 4 fins, we also cut holes into parachutes for faster decents and no holes for slower descents. We color code the rockets so we know what we have inside the rocket before launch. Red with white nose cones are parachutes with no holes, red with red nose cones are those with streamers. Black with white nose cones are parachutes with a hole in them ect...
 
From your last two posts I take it that your team is entered in BOTH the streamer and parachute comps. AND the spot landing comps. right?
And using only modified Alphas and Vikings to achieve two very different objectives, correct?
So to answer your initial question a 6" chute can fit into a bt-50 Alpha tube and could be used in the spot landing comp.
Problem is it might come down too rapidly and sustain landing damage. So if recovery without damage is a requirement then that must be considered.
You know, if you had put ALL the pertinent info (comp rules, what your team is trying to achieve, etc.) in the first post it would have saved everyone a lot of wasted time and trouble.
Permanently outta here.
:rolleyes:
 
Alpha rockets flew well with 6" parachutes, I was surprised that the rocket recovered so nicely. I would recommend using 6" with Alpha rockets as well as Baby Bertha, they do recover much faster than 12" and dont take as long to prep
 
Any rocket that you expect to come down tail first and a bit "hot" (particularly streamer models) or on hard surfaces like asphalt or playa will benefit from fins that do NOT extend beyond the tail of the body tube. Such fins are a bit less efficient (for minimum but acceptable stability, you will need larger fins when the fin's net central point is further forward to get the same CP as a smaller fin hanging partially beyond the tail of the tube) but decrease your probability of damage, as the motor casing sticking out the back takes the brunt of the initial impact.

If you are having problems with a 12" parachute in an Alpha, you need to do a bit of research and practice on parachute packing.

You want a challenge, try getting BOTH parachutes in an Estes Venus Probe or ExoSkell!
 
BABAR said:
Any rocket that you expect to come down tail first and a bit "hot" (particularly streamer models) or on hard surfaces like asphalt or playa will benefit from fins that do NOT extend beyond the tail of the body tube. Such fins are a bit less efficient (for minimum but acceptable stability, you will need larger fins when the fin's net central point is further forward to get the same CP as a smaller fin hanging partially beyond the tail of the tube) but decrease your probability of damage, as the motor casing sticking out the back takes the brunt of the initial impact.

If you are having problems with a 12" parachute in an Alpha, you need to do a bit of research and practice on parachute packing.

You want a challenge, try getting BOTH parachutes in an Estes Venus Probe or ExoSkell!
Click to expand...
Note we use 12" for parachute Duration, 6" was introduced for our rockets to fall to the landing spot faster, I was shocked that 6" did its job and kept the fins on when it hit asphalt.
 
Matt_The_RocketMan said:
Note we use 12" for parachute Duration, 6" was introduced for our rockets to fall to the landing spot faster, I was shocked that 6" did its job and kept the fins on when it hit asphalt.
Click to expand...

Wait, you did use the 12" parachute for this competition for duration? And the 6" was just for landing accuracy? Boy, was I mixed up. This whole time I thought it was a duration competition that required a 6" parachute. *tosses papers into the air*
 
Nytrunner said:
Why were you shocked?

Did no one on the team perform any parachute calculations or decent speed calcs to get a rough idea of what you could expect before pressing the button?
Click to expand...
We were expecting our altered rocket to land quite hard with the amount of parachute we were testing. Usually when we use 1" diameter by 12" parachute with a typical Alpha rocket we usually see some broken fins if the rocket lands on a hard surface, i was expecting the same type of decent rate with an Alpha + 6" parachute...
 

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