SAAB RB-05A-98 Build

Ok, here goes.

I've been meaning to do a build thread for a while. I've built a few rockets, followed a lot of you on here, commented a few times, but never shared a rocket build. The closest thing I have to a build thread is the homemade GPS tracker I made a few years ago using Derek's pre-printed boards (which still works great BTW).

Picked up the SAAB kit in Wildman's 2014 BS sale. It (along with about 10 other HPR kits and innumerable LPR and MPR kits) sat in storage all of last year as I changed jobs and moved all the way across the country. Finally got a little work area set up in the garage over the holidays and decided this would be my first build.

This build is now open to your review, comments and criticisms .

First thing I did was make an accurate OpenRocket file for the bird. I started by scaling up the 3" version (originally posted by Chris A). After making numerous adjustments and corrections we now have a 4" version.

View attachment Wildman_SAAB_4.ork

For anyone who wants to use this file, all of my mass overrides were made to individual components to adjust for epoxy, AV bay sled weight, nose weight, etc. If you remove the mass overrides you'll be left with the true weight of the raw fiberglass components and you can then make adjustments to your build as needed.

Kit parts with an Aeropack 75mm retainer:


First thing is build the motor mount - that's a lot of centering rings. Sorry, no individual pic of this step

Rings and harness were attached with RocketPoxy. Rings were positioned around the fin tabs by lightly tacking on the fins at their appropriate locations with super glue, snugging up the rings to the tabs, then epoxying them in place. Fins were then removed and the areas where the fins will attach were roughed up with 60 grit sand paper.

I also prepped by body tube and fins. These were sanded using a 60 grit dremel sanding wheel and then I used a razor blade to score the tabs (yep I still score my fiberglass - it works for me)

The holes along the fin slots will be used to inject my internal fillets.

NOTE: I'm actually almost finished with this build; I'm not posting this in real time. It'll probably take me a couple days to catch up the posts to where I am. Guess I wanted to be sure I was happy with it first. Go figure

-brant

As this is my first 4 inch, 4 fin rocket, I needed a new fin alignment tool. So, off I went to PayloadBay.com and used the Fin Guide Tool to create a new template. I taped the template to a piece of foam board and cut out a new guide.

Prior to tacking on the fins, I went over all adjoining surfaces with 100 grit sandpaper to "freshen up" the surface then cleaned them with water followed by denatured alcohol.

Main fins were attached using DevCon 5 minute epoxy. I attach all four fins and slide on the foam guide to hold them in place:


After a few minutes, as the epoxy nears the gummy, but not yet solid stage, I set the rocket upright, pressing all fins tight against the body, pushing the guide as tight as possible on the fins, and check for spacing uniformity between all adjacent fin tips.

And this image is supposed to be rotated. Guess I'll have to figure out why it didn't import correctly


Sometimes, even with your best foam fin guides, your spacing can be off a few millimeters. This check allows me to true up the fins relative to each other. In my experience there's sometimes just one fin that needs to be adjusted a millimeter or two. I hold it in place for another minute while the epoxy finishes setting.

With the main fins tacked in place. I now add the small aft fins like so:

These are also tacked on with the 5 minute epoxy.

Looks good so far Brant.

ChrisAttebery said:

Looks good so far Brant.

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Thanks! this has been a fun build. I really like scale/semi-scale rockets. This one is a little bit of a challenge with its attenuated profile and the need for so much nose weight. I'm really looking forward to finishing up and flying it.

Just a quick post before heading off to bed

I used my usual mix of West 205 epoxy mixed with carbon fiber for the internal fillets.

I measured out 24cc of the epoxy mix (20cc 105 + 4cc 205) with about a dime size of carbon fiber, mixed well (at least one minute). Using a 10mL luer slip syringe (you can buy a box of 100 for less than $10 from most online vet supply companies - or go beg for some at your pharmacy), I injected about 2.5cc into each tab hole for each set of fins:

I keep the rocket level and after injecting the epoxy I use a thin wire, such as excess wire from an igniter/electric match, to push through the hole and push the epoxy slurry along the fin tab. The carbon infused epoxy tends to bunch up around the hole - this helps spread it out inside. The epoxy would probably spread just fine on it's own if it wasn't mixed with the carbon shavings.

I know this isn't a lot of epoxy for the internal fillets, but I feel it's a safe compromise of weight given the large main fin with multiple tabs. I don't want to add any more weight than needed to that aft end.

Here's the rocket assembled with the internal fillets complete:


Tomorrow we get external fillets and nose weight. Yay!

Ok, tomorrow plus a few days


Taped up and ready for external fillets

For external fillets I mixed up about 30 grams Rocketpoxy for each set (15g part A, 15g part B), and mixed in black pigment. Yes, I could use any color pigment for this but I have a lot of black sitting around still. I let the mixed epoxy sit about 15 minutes before applying to the rocket - this allows it to degas which usually gives me really nice looking fillets


Apparently, I'm a bit rusty, having not built a rocket in a year, and apparently my time off shows in my fillets. I had to patch up a few spots with bondo patch putty. Great stuff for quick fixes. You usually don't need any patching-up with the Rocketpoxy - goes on real smooth when done correctly.



So...Nosecone weight. Anyone who has built one of these (or a similarly shaped, vertically impaired rocket) knows that it needs a shittonne of weight up front. I added just a hair over three pounds to the nosecone - 48 ounces of powdered lead plus the weight of the epoxy. I had to mix 50mL of West 205 for every pound of powdered lead. This is the first time I've tried using powdered lead and that is some thirsty stuff - need to use a lot of epoxy to wet it up. I'm wondering if you wouldn't actually use less epoxy and space just using really small lead weights, like 1/8" diameter lead fishing weights that you can buy on Amazon or pick up at BassPro. Maybe not.

To keep the epoxied lead in place I drove a 8d, 3 inch nail through the nosecone about 5 inches up from the tip and trimmed it flush to the nosecone with my Dremel (I thought I had a picture but must not have pressed the button hard enough). Plus I added a few washers along a piece of all-thread that will run up from the tip to the eye-nut.

The top washer is 1.25 in diameter.

I figured out how long a piece of all-thread I needed for the three pounds of lead by measuring the volume of a pound a lead (poured it into a measuring cup) then multiplying that volume by three. I used some old wheat grains I had around and poured the equivalent volume for three pounds of lead into the nosecone - measured how deep that went, added what I needed for the eye-nut and nuts, and that's what I cut off to use.

All nuts are secured with thread-lock and the top nut above the eye-nut is a lock-nut - it's not going anywhere.

Nosecone with lead weight, all-thread, nuts and washers is about 65oz.

Several coats of Rustoleum filler primer and some vigorous sanding around the fillets and I now have some beautiful fillets around all these fins

The booster with its white base coat - I'm using Wicked Colors paints by Createx.


I do most of my painting in my high-tech garage paint booth:

Two heavy duty moving boxes - 18" x 18" x 24" - inverted.
There's a 6" duct starting collar at the top to which I have 6" ducting that runs to a blower. I tape a furnace filter to the inside top box to help filter paint particulates


The blower's rated for 650cfm and is bolted to my garage wall and vents outside. It's a good industrial grade blower that I picked on Ebay a few years ago; it had a damaged flange, which didn't matter to me, so I got it cheap-ish (<$100).
The ducting going to the paint booth slips off the top collar of the booth and can be positioned above my workbench to vent epoxy fumes and dust when I'm working.
This blower is one of the best investments I made in this hobby.

Edit: forgot to mention that I control the cfm on this blower through a Variac AC voltage regulator - you don't always want it to suck full strength.

Slick!

Nice paint booth. I might have to consider that as the pollen season is on and painting outdoors is off.

Brant,

Really great job putting the Saab together; it's looking fantastic! Glad to hear you're putting a few pounds of lead up front...she needs it! Keep up the great work; really looking forward to seeing this bird take flight!

-Eric-

Igotnothing said:

Slick!

Nice paint booth. I might have to consider that as the pollen season is on and painting outdoors is off.

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Thanks. This set up is a Godsend. I used to wait until there was good weather out to paint - now I can do it year-round (my garage is finished and lightly insulated - which helps). It actually works really, really well. That cardboard will last years. The more you paint in it, the tougher it gets. You can move it up or down to accommodate different size rockets. With the blower that I attached, I can paint with a touch-up airgun like this and it makes quick work of painting a rocket.


Most of the overspray is very well contained in the booth. I do need to change out the furnace filter at the top frequently. It gets plugged with paint quickly - just buy the cheapest one at the hardware store.

ECayemberg said:

Brant,

Really great job putting the Saab together; it's looking fantastic! Glad to hear you're putting a few pounds of lead up front...she needs it! Keep up the great work; really looking forward to seeing this bird take flight!

-Eric-

Click to expand...

It's a beautiful rocket. The nosecone surprises me every time I pick it up - it's so top heavy. Sometimes when I go to move it I instinctively grab it with just one hand and then it starts to tip over on me because of the weight and I have to grab it with my other hand too.

Hoping to get the first launch in at the end of April at our club's launch. Time to get to work on the AVbay

Can we have an update please?
I have the same bird in the original box from Wildman somwhere in my workshop. Great motivation to read your post!
Your work is just superb and awesome... can't wait to see more pics...
Denis

legranddudu said:

Can we have an update please?
I have the same bird in the original box from Wildman somwhere in my workshop. Great motivation to read your post!
Your work is just superb and awesome... can't wait to see more pics...
Denis

Click to expand...

Thanks for your comment Denis. I'll have some more pictures up tonight or tomorrow morning, depending on what time I get in. Got paint on most of it and I'll be fussing over the altimeter sled this weekend.

-brant

Sorry for the break in this build. I started two other rockets last week and set this aside for a bit.

As I mentioned, I did get a coat of paint on this bird. I'm using Createx Wicked Colors for this. I still use rattle cans for some jobs, but a couple years ago i picked up an airbrush to play with then later got a small touch-up airgun and built my fancy-schmancy paint booth, so I spray from bottles a lot now.

Being a semi-scale rocket I'm going to sort-of stick to the standard white base with a yellow or red ring up top by the coupler like this:
View attachment 286985

I have to say sort-of standard because I'm not just using a plain gloss white on the body. About a year and half ago I ordered a few small 2 oz. bottles of some Wicked Colors Pearl (sparkly) paints. Well, they mistakenly sent me two large 16 oz bottles for white, plum, orange and yellow.

(size ordered on the right, size received on the left

I need to use it somewhere so I'm going to have a sparkly SAAB missile. No rainbows or ponies on this one - just pasty, white, vampirey sparkles.

Here it is with some paint - doesn't sparkle so well indoors. I'll try to get another picture outside today




And I'll probably get that vent band painted today too - I'm thinking sparkly yellow

Ok, vent band painted. Yes, sparkly yellow won out.


The only issue with the Createx colors is that they are water based. I'll be covering this paint job with a few coats of Dupli-color clear coat finish. I found (probably by accident) that this overcoats and seals the Wicked Color paints very well.


I'll apply the clear coat in a few days after I'm sure the paint has had enough cure time - I usually give it 2-3 days.

That turned out great! Love the look of the SAAB!

I was brought to my attention that I may have abandoned this thread without any flight updates.

I flew the SAAB twice last year. The first flight was just a shakedown flight at OROC's Spring Thunder launch with a CTI 54mm J760 White Thunder. Flew to 3900 ft. Flight was stable and it recovered under chute nicely. I brought this down with a 58" standard Top Flight chute - nothing any bigger will fit in the nose. This flight used a 24" chute for a drogue.

I flew it again a few months later at Summer Skies on a CTI 75mm K661 Blue Streak. Flew to 8060 ft. Again stable with a nice recovery. I again used a 58" standard Top Flight chute but changed the drogue to a Giant Leap 36" chute (with a spill hole). I changed to the larger drogue because I thought the 24" was still letting the weighty nosecone drop too fast relative to the body. The 36" drogue was a good choice.

I don't have any flight photos but here is a nice one with me being happy next to it after setting it up at the Summer Skies launch.

Good looking rocket too!

Congrats on great flights and rocket

Love the look of this. Might have to build one after a Nike Hercules I have in mind...

Nice job.

BABAR said:

Congrats on great flights and rocket

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Thanks! It's a fun rocket to fly.

OverTheTop said:

Love the look of this. Might have to build one after a Nike Hercules I have in mind...

Nice job.

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Thanks. It would make a good addition to any fleet. With the shorter body tube length you are limited to 3-4 grain motors, but she's light enough to get some good altitude, even with that heavy nose.

-brant

Great job. One of my favorite rockets that I have yet to build. You may have just pushed me over the top to go ahead and place an order!!!

amarillo_rocket said:

Great job. One of my favorite rockets that I have yet to build. You may have just pushed me over the top to go ahead and place an order!!!

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Thanks. Glad you like it. I can push harder if you need some help.

Only if you can help my wallet!!!!

amarillo_rocket said:

Only if you can help my wallet!!!!

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Well, I would only be good at helping to lighten up a wallet that's already too heavy.

How much weight did you add to nose cone?

crossfire said:

How much weight did you add to nose cone?

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I used three pounds of powdered lead plus 50 mL of epoxy per pound to hold it in, plus the weight of the all-thread, washers and nuts. See post #6 above for additional details. I'm not sure of the total weight added when accounting for the hardware, but it's probably another half pound.

-brant