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Min Diameter builds. 38mm and 54mm
#1
So this is actually going to be a continuation of a thread I made on TRF sometime last year. I had built a 38mm MD out of phenolic and fiberglass and shredded it on an I800. Lessons learned, larger root edge on the fins. If you want to view the original thread, you can do so here: http://www.rocketryforum.com/showthread....drag-racer

So now I'm going to start over. This time the airframe will be all carbon fiber except for the nose cone. The tube will be hand rolled using soller composites 2x2 twill carbon fiber fabric. The ultimate goal on this rocket is to shatter the Tripoli I motor altitude record.

Now as for the 54mm... That will be made out of the fiberglass that I will be practicing with. Will be very similar in design, just larger. And it will be made to fit a CTI 6XL. However I will probably only fly it on 1-5grain motors, as the highest waiver I can get is Potter's 20,000'. Building will start sometime tomorrow afternoon.

Pics of the original 38mm:
   

NAR# 98194
Level 1: CTI I-216, 3,043'
Level 2: CTI K-740, 5,999'

Personal altitude record: 12,400' CTI L395
2014 total impulse: 9,018.2 Ns (76% M)
2015 total impulse: 7,171.7 Ns (40% M)
2016 total impulse: 18,664.2 Ns (91% N)
2017 total impulse: 8,281.1 Ns (80% M)
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#2
Interesting... what motor are you considering for the altitude attempt?



Later!

--Coop
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#3
(08-06-2015, 04:57 AM)Coop Wrote: Interesting... what motor are you considering for the altitude attempt?



Later!

--Coop

CTI 5grain I216 Classic. 99% I

I'm going to stick a J94 into it at some point as well. Only 8 more Ns but open rocket says 1000' more in altitude.

I may also make an extention to the body in the future so I can stick a Loki J1026 and attempt that record as well. But that's a maybe.

Build will be delayed as I was going to a friends help on making my fiberglass practice tubes. However neither one of us has Mylar or peel ply so I'm ordering that today for use sometime next week.

NAR# 98194
Level 1: CTI I-216, 3,043'
Level 2: CTI K-740, 5,999'

Personal altitude record: 12,400' CTI L395
2014 total impulse: 9,018.2 Ns (76% M)
2015 total impulse: 7,171.7 Ns (40% M)
2016 total impulse: 18,664.2 Ns (91% N)
2017 total impulse: 8,281.1 Ns (80% M)
Reply
#4
Well the J94 motor does have the longer burn time.... bet it would take the MD bird on a nice flight!

I don't do MD because it's really not something I'd feel comfortable with, so I ask this from a point of complete ignorance:

Would it not be better to do a flying case design rather than MD when going for altitude attempts, or can having an airframe give an advantage?


Later!

--Coop
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#5
(08-06-2015, 08:54 AM)Coop Wrote: Well the J94 motor does have the longer burn time.... bet it would take the MD bird on a nice flight!  

I don't do MD because it's really not something I'd feel comfortable with, so I ask this from a point of complete ignorance:

Would it not be better to do a flying case design rather than MD when going for altitude attempts, or can having an airframe give an advantage?


Later!

--Coop

Yeah. I kinda wish the J94 was an I just for that reason.

A flying case would probably be better. However with the smaller CTI motors (54mm and smaller) they are a little more difficult to do because of the rounded forward end of the motor casing. That being said, there was a nice 38mm flying case that I saw over on TRF once. To put nose/payload section of the rocket on, he used the motor casing as a coupler and it would separate there, making the nose section a larger diameter than the motor.

NAR# 98194
Level 1: CTI I-216, 3,043'
Level 2: CTI K-740, 5,999'

Personal altitude record: 12,400' CTI L395
2014 total impulse: 9,018.2 Ns (76% M)
2015 total impulse: 7,171.7 Ns (40% M)
2016 total impulse: 18,664.2 Ns (91% N)
2017 total impulse: 8,281.1 Ns (80% M)
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#6
Makes sense...  Was just curious.

I wondered if it was a precision thing with it being such a small diameter... particularly as you said you were using the 54mm as practice. 


Anyways... look forward to hearing more about the project!



Later!

--Coop
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#7
Ordered some peel ply and mylar today. Now it's time to patiently wait to start a couple of builds that I can't wait to start. And one more build will be tacked onto the list... And it may or may not have a 75mm motor pipe... But that's not for this thread.

NAR# 98194
Level 1: CTI I-216, 3,043'
Level 2: CTI K-740, 5,999'

Personal altitude record: 12,400' CTI L395
2014 total impulse: 9,018.2 Ns (76% M)
2015 total impulse: 7,171.7 Ns (40% M)
2016 total impulse: 18,664.2 Ns (91% N)
2017 total impulse: 8,281.1 Ns (80% M)
Reply
#8
What kind of altitude are you siming for the I motor record?
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#9
(08-07-2015, 10:07 PM)BLKKROW Wrote: What kind of altitude are you siming for the I motor record?

Around 15,000'

Although I think that may be a little ambitious. I'll have to wait until the airframe is finally built and all the components in place to get an accurate weight and diameter for the rocket. That being said, my sims for other rockets have always been on the low side, sometimes by up to 3,000'.

Ok so I figured I may as well post the components to the 38mm rocket.

Body tube: 2x2 twill carbon fiber from Soler Composites
Fins: 1/16" 2x2 twill carbon fiber plate from Dragonplate
Nose cone: CTI 38mm nose cone
Motor: CTI 38mm 5grain casing, I216 Classic w/ tailcone closure
Electronics: Featherweight Raven 3 w/38mm av-bay
Tracking: Radio tracking
Recovery: Top Flight 24" thin mill parachute with 10' of 1/8" kevlar shock cord
Deploy method: Dual deploy, drogueless at apogee, home made cable cutter for main

One of the main goals of building this is to have zero empty spaces inside the rocket. The entire recovery system will fit inside the nosecone with room to spare. The shoulder will slide around a coupler tube that houses the tracking transmitter. Underneath that will be the av-bay and under that will be the motor. The nose cone will be turned down on a lathe to match the body tube diameter. I may end up putting a layer of carbon over it to add a little bit of strength after.

NAR# 98194
Level 1: CTI I-216, 3,043'
Level 2: CTI K-740, 5,999'

Personal altitude record: 12,400' CTI L395
2014 total impulse: 9,018.2 Ns (76% M)
2015 total impulse: 7,171.7 Ns (40% M)
2016 total impulse: 18,664.2 Ns (91% N)
2017 total impulse: 8,281.1 Ns (80% M)
Reply
#10
(08-08-2015, 07:54 AM)T34zac Wrote:
(08-07-2015, 10:07 PM)BLKKROW Wrote: What kind of altitude are you siming for the I motor record?

Around 15,000'

Although I think that may be a little ambitious. I'll have to wait until the airframe is finally built and all the components in place to get an accurate weight and diameter for the rocket. That being said, my sims for other rockets have always been on the low side, sometimes by up to 3,000'.

Ok so I figured I may as well post the components to the 38mm rocket.

Body tube: 2x2 twill carbon fiber from Soler Composites
Fins: 1/16" 2x2 twill carbon fiber plate from Dragonplate
Nose cone: CTI 38mm nose cone
Motor: CTI 38mm 5grain casing, I216 Classic w/ tailcone retainer
Electronics: Featherweight Raven 3 w/38mm av-bay
Tracking: Radio tracking
Recovery: Top Flight 24" thin mill parachute with 10' of 1/8" kevlar shock cord
Deeply method: Dual deploy, drogueless at apogee, home made cable cutter for main

One of the main goals of building this is to have zero empty spaces inside the rocket. The entire recovery system will fit inside the nosecone with room to spare. The shoulder will slide around a coupler tube that houses the tracking transmitter. Underneath that will be the av-bay and under that will be the motor. The nose cone will be turned down on a lathe to match the body tube diameter. I may end up putting a layer of carbon over it to add a little bit of strength after.
Quote:I'm replying regarding the question you asked about the CTi cones.
Pictured is a 54, made the same as 38's. Wildman posted this few days ago:

"In case you haven't seen or herd about the new nose cones we are now carrying.
Here is a picture of one that went over Mach 2 and melted the paint off the cone the paint ended up on the body tube with no damage to the cone at all.
The 3 and 4 inch versions have a phenolic tip for even greater heat résistance ."

[Image: attachment.php?attachmentid=269534&d=1437247044&thumb=1]


You'll be fine we these cones.


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Jim Hendricksen
T 9693
L-3 Savannah Ga
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