Kestral - Northern Colorado Rocketry

This topic has 13 replies, 5 voices, and was last updated 14 years, 4 months ago by John A. Wilke.

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April 16, 2011 at 5:25 pm #41244
greywolves
Hey guys,

Watch out 25K here I come. I got my Kestrel fin can done yesterday, turned out great. I again sanded a groove in front and behind the fins for tucking CF into, used a more shallow groove this time, turned out to be a very smooth transition. I think it is a 14 ounce weave, I did 2 layers tip to tip and 1 layer 2/3 up each fin. Each time sure gets easier, even making the bag, which is by far the tricky part.
With the bag still on.

Bag removed and rough trimmed, had a hard time trimming, waited about 30 minutes to long I think.

Sure is fun, now I need to do some light sanding.

What are some of the altitudes others have got with this kit?
April 23, 2011 at 3:19 am #54186
greywolves
Hey guys,

I got the fins on my Kestral sanded down, and thought I’d share another picture. Still need to polish for the final WOW factor.
April 24, 2011 at 1:21 am #54187
SCOTT EVANS
Pretty D@m Nice!
April 24, 2011 at 2:35 am #54188
Warren B. Musselman
Moderator
I’d have to say that looks like a gorgeous job. Makes you wish you had some hand-laid carbon fiber tube instead of PF green tubing…

Nice pictures and a damn nice job. Hope I’m there to see it fly.
May 23, 2011 at 5:14 am #54189
greywolves
Whistles! Come from the crowd, as the newbie presents his biGGest rush yet. I spent 4 hours today teaching my self how to pack the chute in the upper section, 36″ Fruity, No Z-fold here, Quad fold is your man.
I read all the other post on Vent holes, but no one really address Vent hole and sear pins, Do both? Nah, i just use sear? Never fly without a Vent hole? Thoughts?
Bird should reach speeds of 1600+MPH. Using 3, 2/56 nylon screws. I used 2 of the same on Little Blue Dawg, just reaching 803MPH.
So if use a Vent hole, place close to the charge? place away from the charge? place just in front of the piston?
At 25K could I really have a pressure difference of 18 PSI?
All just pft.. minor details. Here is a couple of pictures.
May 23, 2011 at 2:44 pm #54190
SCOTT EVANS
Thats a nice Little Dawg on the left……..but he doesnt look blue! 😉
The thing in the middle looks pretty good too. 😉
May 23, 2011 at 2:47 pm #54191
SCOTT EVANS
Are those rail buttons I see? 😯
How do you mount those, being a minimum dia. 😕
Nobody has introduce Mr Wolves to the tower? 😕
Just like hangen a couple of Barn Doors out in the Wind. 😉
May 23, 2011 at 5:06 pm #54192
edward
Moderator
Shear pins + a vent hole.

On my L3 I had an issue of the main decided to leave at drogue deployment so I had to ground test quite a bit. I ended up with 6-32 shear pins and a 1/16″ vent hole. I would at least upsize to 4-40 and 3 shear pins.

Edward
May 23, 2011 at 10:28 pm #54193
SCOTT EVANS
At 25K could I really have a pressure difference of 18 PSI?

Ya know, I never thought about it, but if that was in there at apogee, might help get the laundry out. At least the nose cone off. 😉
May 23, 2011 at 10:35 pm #54194
edward
Moderator
18 PSI? STP is ~14.7 PSI. To have a difference of 18 PSI you’d have to either be sucking quite a bit or blowing really hard.

Edward

Sarcasm aside:

Atmospheric Pressure at 5,000′ is ~12.2 PSI, at 30,000′ it is ~4.4 PSI. That is a 7.8 PSI difference. Multiply that by the surface area of a 54mm bulkhead (~2.15″ Diameter), 3.64 IN^2 and you get ~28.5 pounds of force.
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