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  #21  
Old 09-10-2012, 10:28 PM
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mbauer mbauer is offline
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Had to Know....

Just cut a fairly large inspection hole. Took a look inside to verify if PSI Tube was bent/kinked.

It isn't, looks nice and straight above the former, will take a chance it is the same below the former-the former is slightly above the truncated cone to 3rd stage connection, would have to cut the cone to look, this will weaken it too much for flight.

Already patched and now for the micro servo to get here for chute deployment system. Already have the computer, batterys, everything but the small servo.

Check with different parachute size programs = FPS = Feet Per Second :
10 FPS = 68" diameter chute
15 FPS = 45" diameter chute
20 FPS = 34" diameter chute

Ideal rate to stop damage and also keep the drift low is around 18 FPS.

Looks like some final parachute system parts are going to be added!

Flight video soon!

Mike

Last edited by mbauer; 09-10-2012 at 10:42 PM.
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  #22  
Old 09-11-2012, 09:54 AM
rstaff3 rstaff3 is offline
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If it was me, I'd go for a bigger 'chute made from some light weight material. How much altitude do you expect to get? I can't imagine drift would be an issue (but then I don't know the rocket eating tree situation at your launch site).

The trouble with long relatively flimsy rockets is that they tend to crimp in the middle if they land on an edge. However, the bigger the 'chute, the move lateral velocity you'll get. I've also had many rockets that recovered undamaged (repeatedly) under light winds suffer fin damage on windy days. So there is a trade there too.

Edit: PS - at low altitude it might be tough to get a big 'chute to actually open. It may actually be better to use the mid-sized 'chute.

In any event, I can't wait for the flight report! Photos and videos please.

PS - I hope my repeated use of the word 'flimsy' doesn't sound derogatory. I assume for paper rockets this is a feature not a bug

Last edited by rstaff3; 09-11-2012 at 09:56 AM. Reason: Didn't fully think before I typed!
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  #23  
Old 09-12-2012, 08:02 PM
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mbauer mbauer is offline
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Quote:
Originally Posted by rstaff3 View Post
If it was me, I'd go for a bigger 'chute made from some light weight material. How much altitude do you expect to get? I can't imagine drift would be an issue (but then I don't know the rocket eating tree situation at your launch site).

The trouble with long relatively flimsy rockets is that they tend to crimp in the middle if they land on an edge. However, the bigger the 'chute, the move lateral velocity you'll get. I've also had many rockets that recovered undamaged (repeatedly) under light winds suffer fin damage on windy days. So there is a trade there too.

Edit: PS - at low altitude it might be tough to get a big 'chute to actually open. It may actually be better to use the mid-sized 'chute.

In any event, I can't wait for the flight report! Photos and videos please.

PS - I hope my repeated use of the word 'flimsy' doesn't sound derogatory. I assume for paper rockets this is a feature not a bug
You've got it right about the heavy cardstock being flimsy. More it gets moved around the more "character" marks it gets!

Parachute material that I'm using is a mylar "space" blanket. Found them cheap and big enough to make several chutes from each blanket. Was able to buy them from work for $1.50 each.

Don't know if 1/4" elastic cord from a sewing department will be strong enough to handle the shock of opening though?!

Shroud lines are nylon beading twine rated at 30lbs. Using avery 3-ring hole paper no-tear rings for support where the shroud lines are attached to the mylar.

Mike
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  #24  
Old 09-13-2012, 09:17 AM
rstaff3 rstaff3 is offline
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My random thoughts...

The 1/4" elastic seems thin to me. The one rocket kit that I have of comparable weight and which came outfitted with an elastic shock cord used 9' of 1/2" elastic. The ability of the elastic to absorb the shock of ejection is based both on length and width. On pyro rockets you need it long because it is common on shock cords for the ejection to stretch the cord to it's limit and then have the nose section spring back and impact the body. In the days of balsa cones this would result in a smile shaped indentation, aka the Estes smile. Now, it results in a bent body tube. The common wisdom is to make the cord twice the length of the rocket. Many will say longer than that.

Be that as it may, I doubt if you need it that long. I have no real basis for this, but I think I'd go with a shorter piece of thicker elastic. I am wondering how you will attach the elastic to the body without a 'hard point' and am worried it will rip free. Maybe thicker cord will help, maybe not.

You could always test it with a 2 lb weight. Attach it to the cord and chunk it off a deck (or whatever). That would at least verify it won't snap. I don't know know to test the attachment point.

Hope this muddies the water
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  #25  
Old 09-21-2012, 09:12 AM
paperairforce paperairforce is offline
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great stuff, Mike! Watching with great interest. 2lbs seems incredibly light for that ten ft rocket, and I wonder if it couldn't take a bit more weight with some epoxy or laquer to help with dings? If I had a place to put it, I would definitely want to build it! cheers

Will
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  #26  
Old 09-21-2012, 01:06 PM
rstaff3 rstaff3 is offline
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I agree that the weight is amazing. or lack of weight, I guess. What I found helps most with poster and foam board rockets is adding an inside structure and more 'formers'. The psi tube of the lower section would help that part at least. Unfortunately, a 10" rocket has a ton more drag than the smaller ones (it grows and the square of the radius) and minimizing weight is likely a requirement.

I'm REALLY anxious to hear how this flies!
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  #27  
Old 09-29-2012, 02:56 PM
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Sevos Got Here This Morning

The servos I ordered last month finally got here this morning. Have 5-different ones to choose from.

Next step is to mount everything to a bulkhead, program the small computer board, make a G switch, and install everything.

Photo shows the batteries, computer board (in static protection bag), different servos (Quarter for reference size), wire, springs, neo-magnet on the end of a small plastic zip-tie will be the G switch.
1:32 Saturn V Alpha Build-parts2.jpg

Spring will be compressed on short length of wood dowel, a pin will hold the spring in compression until the G switch closes the circuit on launch.

After 2-seconds the plan is for the computer timer to send a signal to the servo. The servo will pull the pin releasing the spring. The spring should force the Capsule away from the rocket body deploying the parachute.

Lots of experimental work yet to be done.

As complicated as this sounds, it should be fairly easy to complete.

Total money outlay? Not expensive at all:
+ 1 each Servo = $3.99
+ 1 each Computer Board = $4.35
+ 6 each batteries = $1.92
+ Parachute Material = $1.53 ((emergency survival blanket made from mylar)
+ 1 each Neo-magnet = $.75

Extra servos and supplies will be used in other rockets. The very first 1/12 scale Redstone will be the test bed for the first flight. If it is recovered safely this Saturn V will be launched soon after.
BTW-Bought some extra wide shock cord to try as well.

This deployment system has been used extensively by water rocket builders. I'm just using their ideas to make my system.
http://www.wra2.org/forum/viewtopic.php?f=5&t=1580 -timer and software link
http://waterrockets.multiply.com/jou...-Switch_Part_1 -super neat G switch idea

Hope this works!

Mike

Last edited by mbauer; 09-29-2012 at 03:19 PM. Reason: Forgot to mention Credit for design-
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  #28  
Old 10-27-2012, 11:45 AM
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Electronics Issues

The timer is not working so great. Besides the added weight, it creates a fit issue, and a programing issue.

The rocket is big, but near the CSM area where I planned to install the timer and parachute a big fit issue happened.

The parachute needs to deploy without any "hangups". The timer created too many edges for the parachute to catch on. Added a parachute "box" to protect the chute, hoping to correct this problem. More weight and less space is the result.

Having issues with programming the computer.

If it does eventually work, still don't know how much time to delay it. Altitude, if any, is an unkown, no way to estimate a time delay for this unkown.

Besides if the rocket blows up on launch, the electronic parts can become shrapnel.

Overlly complicated electronic system is getting the boot....

Rocket itself is a simple design.

Working on something else that will hopefully deploy at apogee.

Man, what a drag.....

Mike
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  #29  
Old 10-28-2012, 09:40 AM
rstaff3 rstaff3 is offline
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It would have been nice to see how the timer worked but it does sound like there are quite a few problems with the set-up. I still am anxious to see how such a huge paper model could fly!
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  #30  
Old 01-08-2013, 02:58 PM
rstaff3 rstaff3 is offline
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Hey Mike....any updates?
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