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g_boxwood

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Dear Gentlemen,

here I am to report about my last (and first) medium/big project and ask for some advises.

I'll post just few pics to introduce the 'problem'.

I decided to lighten the stock fins (1/4" birch ply) and fill the holes with balsa cores in order to save weight and let the composite reinforcement do all the job of withstanding flight stresses.

Here are the fins from stock to beveled and lightened.
 

g_boxwood

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Here they've been epoxied to the MMT (3") and 2-part automotive putty fillets have been added and sanded smooth; the balsa cores were added and sanded prior to that.
 

g_boxwood

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The whole fincan received its first reinforcement: I called it an 'internal fin-to-fin' and I used 'heavy' (more than 6oz) carbon cloth.

Here you can see the finished fincan next to the slotted booster section (reinforced with Giant Leap Kevlar sock veiled with their EASYGlas sock).
 

g_boxwood

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The reinforced fincan was then slid into the booster, fillets were added and the external tip-to-tip fiberglass (6 oz.) reinforcement went next.
 

g_boxwood

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Now the question:

would you reccomend another external tip-to-tip layer of f/g or not?

Let me say that I plan to fly this model with the biggest motor that fits (L850W) in the future; I also know that this kind of questions is pretty common (I remember of Carl replying to/talking about a similar subject) BUT in my case I'm not reinforcing a G10 or 'full' birch fin but a lightened/weakened one; since I wanted the reinforcement to work it may be necessary to add an extra layer.

What do you think?

Thanking you in advance,

Giacomo
 

DPatell

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If you ask me, you're allright. I put 3/32" balsa through mach with one layer of 4oz. glass tip to tip, I bet you'll be fine. Sure looks awesome though, your building techniques are flawless! I can't wait to see the finished pictures:)
 

Ryan S.

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wow.


That thing is a tank. It must we extremely strong. You have amazing building technique and I think your fins should be fine
 

rstaff3

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Nice job! I wouldn't think that the fins are weakened much after you added a lamination of Kevlar and then a glass top layer :) I'll leave it to more experienced HPR folks to advise on the second layer of glass, but I'd be surprised if it was necessary.

After that heavy Kevlar sock, carbon on the fin can, and automotive putty fillets, I'm not sure you saved all that much percentage wise by adding the cutouts, but they looked cool ;)
 

g_boxwood

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Originally posted by rstaff3
I'm not sure you saved all that much percentage wise by adding the cutouts, but they looked cool ;)
I agree but that was a try! I kept a weight-log to track the incremented/decremented weights troughout each building step and it came out that beveling, lightening and adding the balsa cores brought each fin weight down to half that of the original stock fin (from 179gr to 89gr). Multipied by three that saved something less than 10oz. I didn't want to gain few extra inches in altitude but to keep the aft end a little lighter (considering I was going to heavily reinforce it) and to evaluate the pros/cons of the extra time spent in order to see if it would have been worth it. That's all and thank you for pointing out!

Ciao,

Giacomo
 

g_boxwood

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Originally posted by Kcee
I see we think a like on certain things.
That's great Kcee! We had the same thought on the same part of the same rocket! That explains why some theorems have more than one name related to them!!!

BTW nice work, I love the 'all black' look of the booster!!! Are you building it for some cert flight? I should launch it on 27th March IF
I get the Aeropack retainer & adapter in time...

Thank You for sharing,

ciao,

Giacomo
 

Kcee

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Hi Giacomo

This will probably be my CAR L4 rocket I'm going to fly it on a Ceseroni L1090 in July at Roc Lake in Alberta Canada
And a M1400 for my L4 when I get the money and the guts to do it :)

Kevin
 

g_boxwood

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Originally posted by DPatell
I can't wait to see the finished pictures:)
Here I am after some recent first-hand finishing work...

The model is now ready for its first flight/L2 attempt next Saturday (27th March). I won't give it a full paint job for the moment (it will be done by a professionist friend of mine after the flight, if everything goes fine).

I primed it once to get the feeling of where to fill, I filled the cloth weave (entire tubes) with some extremely sandable filler, sanded it with 400-grit and then gave the other 4 primer coats with 600-grit sandings in between.

I also put some more pictures in a Yahoo! Photo Album; here is the link:

http://it.f2.pg.photos.yahoo.com/ph/g_boxwood/album?.tok=ph7NzzABsjlfsf5L&.dir=/a2a2&.src=ph

Ciao,

Giacomo
 

Ryan S.

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very nice, your filler looks like the stuff I am using right now. The finish looks great!!!
 

g_boxwood

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Yes I read about it on Your MI thread; it may be; mine sands easily DRY with 400-grit while it melts somehow if it comes in contact with alcohol and/or epoxy (I use 2-part-automotive filler for those jobs); therefore it can't be wet-sanded but the sandpaper doesn't clog too much even dry.

Ciao,

Giacomo
 

Ryan S.

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that is strange, I am hope mine doesnt do that, but I dont think there is anywhere it is going to come in contact with epoxy. This stuff I use sands very very easily but I think I might have been using a lower grit paper.

Either way that rocket looks great. It deserves a good flame paint job!
 

g_boxwood

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Finally I got my chance to attempt L2... and I've been lucky enough to succeed!
To sum things up a bit: modified LOC Big Nuke 3E for dual-deployment from a single compartment (as described here http://www.rocketryforum.com/showthread.php?s=&threadid=7840) via ARRD and ProXP R4C (as pilot/drogue) & R12C, dual altimeter recovery setup (PML Co-Pilot & Olsen FCP-M2 as a back-up), AT J800T in the **tt w/o ejection.

I think some pics are a must; here are the links:

- loading her (9 kg) on the rail (still needs to be finished...):

http://www.argoshpr.ch/Images/Launch_2004_05_23_Dany2/P5230166.JPG

- lift-off sequence:

http://www.argoshpr.ch/Images/Launch_2004_05_23_Guido/PICT0106.JPG

http://www.argoshpr.ch/Images/Launch_2004_05_23_Guido/PICT0107.JPG

http://www.argoshpr.ch/Images/Launch_2004_05_23_Guido/PICT0108.JPG

http://www.argoshpr.ch/Images/Launch_2004_05_23_Guido/PICT0109.JPG

http://www.argoshpr.ch/Images/Launch_2004_05_23_Dany2/P5230187.JPG

- recovery:

http://www.argoshpr.ch/Images/Launch_2004_05_23_Ralph/IMG_3630.JPG

For other event-related pictures just log on the Swiss ARGOS group homepage at www.argoshpr.ch

Thank You, hope You enjoyed!!!
 

loopy

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Great shots, too! Congratulations on your cert flight. Great pics, and looks like an amazing place to launch from too!

Loopy
 

daveyfire

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thank u, next
You may say it's unfinished, but I think it looks AWESOME. What motor did you use on your cert attempt? Looks like a J460T. When does she get the L850W? I can't wait for that!
 

g_boxwood

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Originally posted by daveyfire
Looks like a J460T. When does she get the L850W? I can't wait for that!
It's a J800T; I'll probably proceed this way:
- Italian meeting (July 16-17-18) K550W or K695R or K1100T
- Swiss meeting (September 19-20-21) K700W or K1275R
- Spanish meeting (October 7-8-9) L850W

mainly depending both on reloads availability and finances at the time ;) .

By the Italian meeting I hope to set up a 2.4 Ghz wireless video cam. I don't think I will invest in finishing her by the time. I still need to airbrush the lightning that runs along the a/f to the fins (where the base coat blends with the carbon, as you may have seen in the picture where she's being loaded on the rail) in 4-5 shades of blue. I have to do it for the sponsor!
 

Ryan S.

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wow that thing looks great, and the liftoff pics are awesome

Big congrats on the cert
 

DPatell

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Very nice! I love the extra reinforcement;)

How much did that sucker weigh?
 

g_boxwood

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Originally posted by DPatell
How much did that sucker weigh?
Exactly 9 kilos as ready to fly with the J800T installed; something more than 'a little bit' on the heavy side but as you say, 'Put in a bigger motor!'
 

DPatell

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Wow! That converts to 19.8 pounds. That thing is a beast! Looks like it flies great, though! Should be pretty awesome on the L850, but until then the K1275R will be awesome:)

How high did it go on the J800? I didn't see an altitude report...

This is really cool, I have a similar project in the works, this is going to be great to look at in terms of weight and reinforcement.
 

g_boxwood

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Originally posted by DPatell
How high did it go on the J800? I didn't see an altitude report...
Olsen FCP-M2 reported 2043 ft, PML Co-Pilot/RRC2 said 2324 ft...
It was a pretty powerful flight in the end; the only handicap is that You'll need to choose higher average thrust reloads to achieve stability within the rail (and that means You won't be able to fly some great 54mm reloads :( ).
 

g_boxwood

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I put my hands back on the Nuke in these last few weeks (she will hopefully fly again on the 17th-18th July together with the upscaled A.C.M.E and DW).

I started the 2.4 GHz setup with molding the microcamera holder/cover: that's actually what the camera is mounted to; it had to be aerodinamic and to be easily retrofitted to the already built booster section.

I made the female mold laying 6 layers of 6oz. onto the airframe...
 

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