Mercury Atlas

[cjp]

Thanks for the compliments everybody...I feel like a rank amateur compared to many of the other builds I see here...:blush:

It is too windy here today to launch, our club had to scrub, so I decided to hit this thing with some primer this morning...I've been like a kid on Christmas...it is finally dry enough to touch (but not sand)...I don't have as much rework to do as I thought...

I put a coat of white on the LES tower and struts because I tested red on the gray primer, and it didn't pop like I wanted (using same red as I put on my Big Daddy, so it should be pretty bright).

I am rethinking my fins...added through the wall tabs and slotted the tubes so I can glue the plastic tabs together hoping for a better bond of plastic-to-plastic. Also rather than the twist-lock mess, I just added a short 1/8" dowel that will fit into a hole on the bottom of the booster to prevent rotation, and use tape to friction fit the fin tubes in place.

Edit: and yes, I got in a hurry to primer the fin tubes and forgot the dowels!!!

Wow!!!!You Sir are a Master Builder.I'm scratch building a Gemini Titan and ashamed to post pictures after looking at your build as well as others(Qquake2k,Scottydog and others)I'm not as talented like some of you,but I'm learning.Really nice detail on your build.

 

[rocketguy101]

Wow!!!!You Sir are a Master Builder.I'm scratch building a Gemini Titan and ashamed to post pictures after looking at your build as well as others(Qquake2k,Scottydog and others)I'm not as talented like some of you,but I'm learning.Really nice detail on your build.

by all means, post away!! it is intimidating, but then its like taking your bird to a club launch and letting the other flyers look at your handi-work. this is a friendly forum and has been supportive of my endeavours. i would like to see your GT.

 

[cruzsergio]

Wow!!!!You Sir are a Master Builder.I'm scratch building a Gemini Titan and ashamed to post pictures after looking at your build as well as others(Qquake2k,Scottydog and others)I'm not as talented like some of you,but I'm learning.Really nice detail on your build.

I'll share mines if you share your's !

 

[qquake2k]

Wow!!!!You Sir are a Master Builder.I'm scratch building a Gemini Titan and ashamed to post pictures after looking at your build as well as others(Qquake2k,Scottydog and others)I'm not as talented like some of you,but I'm learning.Really nice detail on your build.

You have nothing to be ashamed of, Carl. You build some beautiful rockets!

 

[rocketguy101]

Did anybody notice something wrong with the last picture in the last group I posted??

the dowel was glued to the wrong end of the fin tube!!! oint:

I discovered that when I got ready to mask the tube and paint it black -- I planned to paint the first 1" silver, the rest (the fin end) black hoping it will look like nozzles. It puzzled me for a minute, wondering why I would be masking over my fin slots then DOH!

I cut the dowels off, scraped paint off the correct location, and re-glued the dowels. I then drilled a 1/8" hole in the bottom of the rocket (actually had to ream it out a bit so the dowel would slide in). So you can see now how I will keep the fin tubes from rotating. I may even apply some masking tape.

Looking at the Estes MR K-41 instructions, a piece of string is tied around the nose to tie the parachute bridle to. I was afraid string might wrap around part of tower and pop it off when the chute opened, so I used some 24 ga steel wire to make a loop that tucks up under the aerodynamic shroud. I have epoxied it in place. That groove cut in the shoulder is to vent the tube as it is sealed on the other end. I plan to glue the nose to the transition, and before I cut the groove, there was a piston effect as I pushed the nose down.

 

[rocketguy101]

BWAHAHAHAH!!!! It is painted!!!! The tower is on!!! The fins are complete!!!!

I went with the "frosted" paint scheme since the all-shiny models don't look "right" to me...the iconic pic is John Glenn's liftoff, so I went for that.

I painted the entire model white (Duplicolor Lacquer). I masked part of the nose about 1/8" around the base and painted red, then cut a 1/16" strip of tape to mask along the edge formed by the cone and adapter, and masked the antenna housing (.13") then hit the whole nose with flat black.

Rather than use mylar (or trim monokote) for the tank, I tried using Krylon "Metallics" silver, then masked off and used Duplicolor silver for the other metal surfaces (aluminum?). So I had to mask over the shiny silver to shoot the final dull silver. I was pleased to see neither the 3M blue tape nor the Tamiya masking tape reacted with the silver. (That Tamiya is wonderous stuff, well worth it).

I added through-wall tabs to fins, and sanded them to make sure the tabs butted against each other. I glued them to both the tube and each other with Weldbond, and added epoxy fillets to the fin/tube joint (I see some ran )

 

[rocketguy101]

Here are some close-ups of the tank and bits. In that last shot you can actually see the difference in the "shiny" silver and the dull.

When everything is totally dry, I will do a weight and balance check. It looks like from some prelimary checks against RockSim that I need to add .75 oz to the nose (I will glue it on when I am done w/ W&B) I will also do a swing test just to make sure it is stable.

 

[qquake2k]

John Glenn would be proud!

 

[sodmeister]

David ,

That is absolutely stunning ,perfect job !

Looks like we have a lot in common ,I love your craftsmanship and eye for detail :handshake:

Sincerely yours

Paul t

 

[qquake2k]

David ,

That is absolutely stunning ,perfect job !

Looks like we have a lot in common ,I love your craftsmanship and eye for detail :handshake:

Sincerely yours

Paul t

He must be OCD like you are, Paul. :tongue:

 

[rocketguy101]

He must be OCD like you are, Paul. :tongue:

HAH! Yeah, I must be, because when a friend posted this, I understood completely...

Thanks for the compliments, can't wait to fly her!

 

[cruzsergio]

BWAHAHAHAH!!!! It is painted!!!! The tower is on!!! The fins are complete!!!!

I went with the "frosted" paint scheme since the all-shiny models don't look "right" to me...the iconic pic is John Glenn's liftoff, so I went for that.

I painted the entire model white (Duplicolor Lacquer). I masked part of the nose about 1/8" around the base and painted red, then cut a 1/16" strip of tape to mask along the edge formed by the cone and adapter, and masked the antenna housing (.13") then hit the whole nose with flat black.

Rather than use mylar (or trim monokote) for the tank, I tried using Krylon "Metallics" silver, then masked off and used Duplicolor silver for the other metal surfaces (aluminum?). So I had to mask over the shiny silver to shoot the final dull silver. I was pleased to see neither the 3M blue tape nor the Tamiya masking tape reacted with the silver. (That Tamiya is wonderous stuff, well worth it).

I added through-wall tabs to fins, and sanded them to make sure the tabs butted against each other. I glued them to both the tube and each other with Weldbond, and added epoxy fillets to the fin/tube joint (I see some ran )

This looks like the real one !
wow !
i love the clear fins !

 

[thobin]

Looks great, this has been a fun build to watch. Great job!


TA

 

[rocketguy101]

I weighed the model and measured the CG.

Weight empty w/ 2 18" chutes, .75 oz lead in the base of the nose, fins in place = 7.25 oz. The CG measures 12.32 inches from the tip of the Mercury nose (not the LES tip!!).

Weight as above plus a D12-5 motor = 8.89 oz. CG measures 13.79 inches from the nose.

Now things get a little complicated...in my original RS file and the CAD model, I made the fins 90 degrees apart on the fin tubes. During the build, when I decided to use the dowels for lock pins, I marked the locations with a 3 fin pattern so my fins are 120 degrees apart. I went back to RS and adjusted the fins to match the actual build, and found the CP moves forward, reducing the static stability margin.

I performed a swing test, and the rocket is stable (people have been asking me "aren't you afraid to fly that?" and my answer is "not really, I am more afraid of swinging it around my back yard on a string, hoping my knot holds or I don't get dizzy and fall down breaking the rocket" I get some strange looks...)

So...if the fins are 90 degrees, RS calculates the CP to be 16.42 inches, and the stability margin is 1.01. With 120 degree fins, RS calculates the CP at 15.87 with a margin of .80 -- but the swing test is stable. Attached is the latest RS file for 90 degree fins. I added mass items to get the mass closer, but RS was still a couple ounces light, so I over-rode the mass and CG with the actual values. I also notice that even using the over-rides, loading the motor still ends up a bit light compared to my actual measurements.

View attachment MercuryAtlas_45_90.rkt

 

[NJRick]

Beautiful job!!

BWAHAHAHAH!!!! It is painted!!!! The tower is on!!! The fins are complete!!!!

I went with the "frosted" paint scheme since the all-shiny models don't look "right" to me...the iconic pic is John Glenn's liftoff, so I went for that.

I painted the entire model white (Duplicolor Lacquer). I masked part of the nose about 1/8" around the base and painted red, then cut a 1/16" strip of tape to mask along the edge formed by the cone and adapter, and masked the antenna housing (.13") then hit the whole nose with flat black.

Rather than use mylar (or trim monokote) for the tank, I tried using Krylon "Metallics" silver, then masked off and used Duplicolor silver for the other metal surfaces (aluminum?). So I had to mask over the shiny silver to shoot the final dull silver. I was pleased to see neither the 3M blue tape nor the Tamiya masking tape reacted with the silver. (That Tamiya is wonderous stuff, well worth it).

I added through-wall tabs to fins, and sanded them to make sure the tabs butted against each other. I glued them to both the tube and each other with Weldbond, and added epoxy fillets to the fin/tube joint (I see some ran )

 

[Daddyisabar]

Looking Good!

 

[luke strawwalker]

Great job... looks fantastic...

One thing to consider, though... the booster engine tubes of the Atlas are just SCREAMING for some real engine bells... and they're not hard to make... just print a conical transition to your liking using the payload bay.com transition tool onto cardstock, cut it out, glue it up, let it dry, coat it in a layer of white glue, then wrap a length of regular sewing thread around it a number of times, carefully evenly placed, to give the appearance of "hatbands" around the nozzle... let dry and paint to your liking, and voila-- instant rocket nozzles ready to be glued over the "fin tubes" in the outboard booster engines...

Here's some pix of the cardstock nozzle from the Dr. Zooch "Discoverer Thor" kit I built a few years back, over in the TRF Archives... Granted my fascination with "chome in a can" is overstated, but imagine how a couple of these would look on your beautiful Atlas painted gunmetal gray or regular silver?? That last one is a slightly modified (left off the upper "steeper cone" ring) cardstock nozzle from the Dr. Zooch Discoverer Thor, installed instead on the back of the Dr. Zooch Lifting Body Shuttle kit-- my own modification...

View attachment 127908

Again, great work! Later! OL JR

 

[aerostadt]

You could put a wood dowel through the launch lugs and tie a string around the dowel to find the measured c.g. Then you could use trial and error in RocSim placing the missing added mass at different locations until the RS c.g. location agrees with the measured c.g. Is is possible to make new outboard fin tubes with the fins at 90 degrees? I would be tempted to say if you can get extra stability, you should go for it. Of course, you want to RocSim with the correct mass to get the correct altitude, so that you will have plenty of time for the chutes to open.

 

[rocketguy101]

Great job... looks fantastic...

One thing to consider, though... the booster engine tubes of the Atlas are just SCREAMING for some real engine bells... and they're not hard to make... just print a conical transition to your liking using the payload bay.com transition tool onto cardstock, cut it out, glue it up, let it dry, coat it in a layer of white glue, then wrap a length of regular sewing thread around it a number of times, carefully evenly placed, to give the appearance of "hatbands" around the nozzle... let dry and paint to your liking, and voila-- instant rocket nozzles ready to be glued over the "fin tubes" in the outboard booster engines...

Here's some pix of the cardstock nozzle from the Dr. Zooch "Discoverer Thor" kit I built a few years back, over in the TRF Archives... Granted my fascination with "chome in a can" is overstated, but imagine how a couple of these would look on your beautiful Atlas painted gunmetal gray or regular silver?? That last one is a slightly modified (left off the upper "steeper cone" ring) cardstock nozzle from the Dr. Zooch Discoverer Thor, installed instead on the back of the Dr. Zooch Lifting Body Shuttle kit-- my own modification...


Again, great work! Later! OL JR

Thanks Luke, I had considered nozzles like you show, I just ran out of Strib before I ran out of ideas Your examples are beautiful and may inspire me to press on...and yes, I was thinking of darker silver (gun metal may be too dark) for them.

 

[rocketguy101]

You could put a wood dowel through the launch lugs and tie a string around the dowel to find the measured c.g. Then you could use trial and error in RocSim placing the missing added mass at different locations until the RS c.g. location agrees with the measured c.g. Is is possible to make new outboard fin tubes with the fins at 90 degrees? I would be tempted to say if you can get extra stability, you should go for it. Of course, you want to RocSim with the correct mass to get the correct altitude, so that you will have plenty of time for the chutes to open.

Thanks aero...I did perform a swing test, and the model is stable w/ the existing fins...my ramblings above were mainly to point out the differences between RS and the finished model. I just over-rode the RS settings to run the sims. I may build a new set of fins to incorporate the nozzles like luke suggests...I am still recovering from the masking/painting exercise last weekend

BTW I have been following your M-A build and it is looking fantastic!!! I can't imagine the challenge of building a transition as large as yours will be!!!

 

[aerostadt]

BTW I have been following your M-A build and it is looking fantastic!!! I can't imagine the challenge of building a transition as large as yours will be!!!

Thanks, Dave, I really like your paint scheme (real lift-off colors). The flat white and contrasting aluminum with all the details looks really good.

 

[rocketguy101]

Thanks to Ol' JR's suggestion, I made nozzles for the fake fins...had to notch them to fit over the dowel pin. I also had to notch the fins a little.

Rather than use thread for the hatbands, I had some leftover cardstock strips from my Direct Jupiter 120 build that were the correct width (.04"). I also found a Testor's color at Wally World that worked nicely called "Flat Steel"...it is slightly darker than the "Flat Aluminum" or regular silver.

 

[luke strawwalker]

That looks sweet... Very kewl...

Later! OL JR

 

[sodmeister]

Yes indeed ,that`s a nice touch to the nozzles ,very nice !


Paul T

 

[rocketguy101]

Finally! The weather sort of cooperated and were able to launch...winds were about 10-12 MPH, so I was holding my breath, we did wait for a calmer moment. Boost was straight, at burnout it did an interesting corkscrew, so the smoke trail looked interesting--but it was stable!!!

Due to the winds, I had reefed the chutes to reduce drift. The booster landed on grass, but the nose landed on a dirt road and dinged the top of the LES motor, and one strut cracked where it glues to the "V" on the capsule...very minor, all easily correctable.

I had set my camera on burst so I caught the moment of ignition, and then several shots on the way up...whew! I can relax now!!

 

[thobin]

Great action shots. Looks great in flight.


TA

 

[NJRick]

WOW! your Mercury Atlas is just beautiful and these pictures are spectacular!!

Finally! The weather sort of cooperated and were able to launch...winds were about 10-12 MPH, so I was holding my breath, we did wait for a calmer moment. Boost was straight, at burnout it did an interesting corkscrew, so the smoke trail looked interesting--but it was stable!!!

Due to the winds, I had reefed the chutes to reduce drift. The booster landed on grass, but the nose landed on a dirt road and dinged the top of the LES motor, and one strut cracked where it glues to the "V" on the capsule...very minor, all easily correctable.

I had set my camera on burst so I caught the moment of ignition, and then several shots on the way up...whew! I can relax now!!

 

[aerostadt]

Your photo's look terrific! A real master-piece! BTW perhaps you already mentioned this, but what material are the plastic fins and what glue to use to attach them?

 

[rocketguy101]

Your photo's look terrific! A real master-piece! BTW perhaps you already mentioned this, but what material are the plastic fins and what glue to use to attach them?

Thanks! Based on several threads here, I used 0.04" Lexan (ordered from Tower Hobbies) and glued with "Weld-On 16". I had these left over from a Gemini Titan clone.

 

[qquake2k]

Looks like a beautiful flight!