MM Astrobee-500 1:26.23 Scale Sounding Rocket

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Micromeister

Micro Craftman/ClusterNut
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Looking over the Micro Scale building que I noticed a model I've had on the list for several years.
The Aerojet General Astrobee-500 3-staged sounding rocket. My intent was to try to 3-stage it. Well after several recent looks at doing so the best I could do would have been 2 staged but I decided to built this model as a single stage sport Scale instead. If it flys fairly well I may try building another staged.

The model really has some off sizes requiring the use of T2+ Minimum diameter MMX body tubing Only for the Motor mount with 14mm and 19mm main body diameters and a long T2 (.246") third stage probe.
To save as much mass as possible all transitions and centering rings are 110lb Cardstock. the Rings are laminated 3 ply cardstock.
Fins are on piece .032" Basswood.
Shock-line and Anchor are a combination of 49strand Stainless steel Beading Wire with 30" x 70lb Kevlar.
This model will use a 1/2" x 12" Yellow PTFE Streamer Wadding.

MM 407uc01a_Astrobee-500 Scale Plan & base Parts_08-26-14.JPG

MM 407uc01b_Astrobee-500 T2+ MMT Boattail & Nozzle_08-26-14.JPG

MM 407uc02_Astrobee-500 MMT & Stainless Shockline anchor_08-26-14.JPG

MM 407uc03_Astrobee-500 Body&Fins_08-29-14.jpg

MM 407uc04_Micro Astrobee-500 Base construction Done_08-30-14.jpg

View attachment MM 407c_MM Astrobee-500_26.23 Scale T2toT20+(x5) (8.5x14)_08-12-14.pdf

View attachment MM 407f1c_MM Astrobee-500_26.23 Scale Shourd&Ring Sht(x5)_08-12-14.pdf
 
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She's done!
Primed, Sanded, Painted two colors white & black. Finished decals and Pledge w/ future yesterday. Added 1/2" x 18" green teflon Streamer/Wadding and took the photo below a couple minutes ago.
Still need to Swing test the finished model...perhaps tomorrow.
That Said; by Hook or Crook This little beasty will be on the field Saturday Sept. 20th for a first test flight.

MM 407uc05_Aerobee-500 26.23 Scale complete_09-09-14.JPG
 
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Completion Photo taken.

I did add .3g of nose weigh to this just to move the CG to a point where I could use the forward Launch lug as the attachment point to swing test the model.
Swing test with positive results:) Can't wait to put this one in the air. If all goes will I forsee a sister model that will be at least two staged if not all three:)
It is a large Micro model so I do not expect much in the way of altitiude for this test model with a liftoff weight of 17g.

MM 407p01_Astrobee-500 (26.23)_09-09-14.jpg
 
Amazing result. Do you have a jig to sand the nc and small tube and what sandpaper do you use?
 
Amazing result. Do you have a jig to sand the nc and small tube and what sandpaper do you use?

Nothing special: I use Glit-Stick Sanding belts, standard 120,240,360 grit Sandpapers, various size sanding blocks made from 1"x1"x12" balsa and smaller for special needs.

Like just about everybody in the hobby, I really dislike all the sanding but bite the bullet to get a decent finish. The trick is to let the papers do the work, don't push it, take your time and sand in small circles.
My primer is the cheapest Auto Grey, Brown and black sandables I can get my hands on..Why? because we are sanding off almost all of it. It seems to me to be a total waste of money paying over 1.50 for a can a sandable primer. I'm currently using Colorplace Auto primer from Wal-Mart at .88 per 12oz can.
The method is much more important then the material! Apply 3 heavy wet coats of primer one right after the other about 1 minute apart. let this flash off from about 20minutes. Checking every so often to see if wood grain or body seams still show. If they are still deep and pronounced apply another 3 coats as before making sure to stay within the 1 hour recoat time. At this point let the model sit for a minimum of 3 days. The can says wait 7days but unless you've really put it on thick and have very heavy humidity 3 days is generally good. DO USE THE SNIFF test to check for outgasing thinners. If you can smell it, it's not ready for sanding.

Sanding starts with 120 to knock down the big stuff, quickly changing to 240 before you reach the underlaying color primer. Continue sanding until you reach the base color primer at which point I switch to 320-360 to smooth out the entire surface. If I find I need another coat or two of primer (almost never) spray a light coat and let dry overnight before finish sanding with 360 then sniff test again to see if the model is ready for Base color coat. If you can smell it, it's not ready for recoating.
I thing that seems the hardest part is the Waiting. Patients is something that has to be developed over time:)

c-sm_Glit-Sticks & Excel sanding sticks & belts_07-21-05.jpg

b-sm_1 x 1 x 11 Sanding Blocks_07-21-05.jpg

d-sm_Flex-I-Flie Sanding frames_07-21-05.jpg

a-sm_9 x 11 sandpapers & fine scotchbrite pad_07-21-05.jpg

Ultra Fine-sm_Scotchbrite #07448 Pads_01-07.jpg
 
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Nice job!
Cant say I've ever seen the Flex-Files or the sanding sticks.
Where might one find those for sale?
 
Nice job!
Cant say I've ever seen the Flex-Files or the sanding sticks.
Where might one find those for sale?

Actual "Glit-Sticks" and Excel sanding band sticks are usually available at your local Hobby store. I got most of mine from either Belleville Hobbies, Tower hobbies or Micro-Mark. But you can get a generic brand holders and better price on the 1/4" sanding bands from McMaster-Carr. the only difference is they only have one RED plastic "Stick".

That Wonderful Flex-sand handle and sanding bands is a Micro-Mark product. They are the only shop I've ever seen that product. An Absolutely OUTSTANDING product for sanding curved surfaces.
 
Actual "Glit-Sticks" and Excel sanding band sticks are usually available at your local Hobby store. I got most of mine from either Belleville Hobbies, Tower hobbies or Micro-Mark. But you can get a generic brand holders and better price on the 1/4" sanding bands from McMaster-Carr. the only difference is they only have one RED plastic "Stick".

That Wonderful Flex-sand handle and sanding bands is a Micro-Mark product. They are the only shop I've ever seen that product. An Absolutely OUTSTANDING product for sanding curved surfaces.

Thanks for the info. I'm going to get me-self some of those Flex-Files sanding thing a ma jigs.
 
Well; This little piggy didn't launched well but do to its 17.4g liftoff mass gives it only about 8 to 10feet as expected. It's still a great Scale model so it'll get flown that 8 or so feet a few more times.

MM 407Lp01a_Astrobee-500 1st Flt On Pad_09-20-14.jpg

MM 407Lp01b_Astrobee-500 1st flt countdown_09-20-14.jpg
 
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