SR-71 Blackbird build thread - FINISHED

[Mushtang]

After finishing my Batman style Hyper-Bat rocket I ordered an R2-D2 rocket from eBay to build for my son, but since that is taking too long to get here I went ahead and started my SR-71.

I got this kit a couple months ago and I've been looking at it from time to time as I worked on other kits wondering how difficult it would be. For some reason this build scares me, and I'm sure I'm going to crash and burn with it. It's a VERY good looking kit and I really want to do a good job, so I suppose if I mess up royally while building it I'll get another one and try and learn from my mistakes.

Taking the parts out of the bag I realized it was going to be different. Probably because this is an airplane instead of a rocket? There's a few tubes, some big sheets of paper, and the usual odds and ends, but still - something about this one makes me nervous.



I read through the instructions a couple of times and looked over all the parts. The paper sheets that go over the wings were already pulled out of their pre-cut sheets, probably knocked out by the parts during shipping and handling. The body tubes had VERY thin seams and I wondered if I could get by with just using primer and not filling with CWF? There's a couple of plastic pieces that the instructions show how to slice up to form the front and back of the wing tubes. And there's a couple of card stock guides for gluing on the fins to help them go on straight.

Having read the instructions, I'm less nervous about the build, but still not super confident.

 

[Mushtang]

The kit comes with 2 balsa sheets, each has 7 fins that have been laser cut. The cut, however, isn't all the way through and unlike a lot of other balsa fin sheets that have been laser cut these don't seem like I could just push the fins out with my fingers. They'll definitely need to be cut out with a hobby knife.

Looking at the instructions I see that the wings are formed in 2 sections each, with a tube in between them. The inner sections (between the wing tubes and the body tube) are covered with paper to give the plane that curved look. This means that the balsa pieces in between the tubes won't need to be sanded, filled, or primed. This section is made up of 3 pieces of balsa that are glued together.

So from each sheet of balsa, 3 of the 7 pieces don't need to be filled, sanded, or primed. After considering my options to avoid doing more work than necessary, I decided to go ahead and fill and sand the entire sheets before removing anything. This would actually be the easiest way even if it meant I was prepping some pieces that would never be seen.

I painted on a watered down mixture of CWF onto each side of the balsa and let it dry.



As it dried I was at the table working on the engine mount and would turn the sheets to try and keep them from warping, but they warped anyway. Before going to bed I laid them flat on the table, put several sheets of paper on top of them, and then my laptop on top of the paper. Sitting overnight like that removed the bit of warp and the next evening I was ready to cut them out.

Here are the 7 pairs of "fins" cut out of the sheets, and all their edges smoothed with 320 sandpaper.

 

[RocketManDan]

After finishing my Batman style Hyper-Bat rocket I ordered an R2-D2 rocket from eBay to build for my son, but since that is taking too long to get here I went ahead and started my SR-71.

I got this kit a couple months ago and I've been looking at it from time to time as I worked on other kits wondering how difficult it would be. For some reason this build scares me, and I'm sure I'm going to crash and burn with it. It's a VERY good looking kit and I really want to do a good job, so I suppose if I mess up royally while building it I'll get another one and try and learn from my mistakes.

Taking the parts out of the bag I realized it was going to be different. Probably because this is an airplane instead of a rocket? There's a few tubes, some big sheets of paper, and the usual odds and ends, but still - something about this one makes me nervous.

View attachment 75208

I read through the instructions a couple of times and looked over all the parts. The paper sheets that go over the wings were already pulled out of their pre-cut sheets, probably knocked out by the parts during shipping and handling. The body tubes had VERY thin seams and I wondered if I could get by with just using primer and not filling with CWF? There's a couple of plastic pieces that the instructions show how to slice up to form the front and back of the wing tubes. And there's a couple of card stock guides for gluing on the fins to help them go on straight.

Having read the instructions, I'm less nervous about the build, but still not super confident.

The kit OOP so I doubt you will find another so don't screw up. There might be a few places left that sell them, but they far and few between.

 

[RocketManDan]

I think it's a nice kit, but the quality of the parts like most ESTES kits are junk. Nothing fits on the kit as you will soon find out. If you join the three pieces that make the wing, avoid sanding the edges. All you will do is change the size of the wing and getting a square edge is a PITA!!

 

[Mushtang]

Recently on these forums I read a thread about the thin walled blue engine tubes that Estes has used a lot in their kits. The top of the engine hook was inserted through the side of the engine tube and used as the engine block and the bottom of the hook held onto the bottom of the engine. The problem seems to be when the engine ejection charge went off the part of the hook going through the wall could pull too hard on the thin cardboard and damage it.

This kit has that thin blue engine tube. Here's a picture of the hook hanging over the end of the tube along with a centering ring, just to show how thin the engine tube looks. Zoom in on the picture and you can see the blue. During ejection the entire force of ejection is put on the tube wall by the hook.



Fortunately I remembered a few of the suggested solutions.

The most common solution was 1) throw the tube in the garbage and use a thicker walled tube. Being new to the hobby I don't have a lot of spare parts which includes zero engine tubes. I guess I could have waited until I went to the hobby shop and bought some replacements but I didn't want to wait.

The next favorite solution was to 2) strengthen the wall of the tube using some card stock. This kit had 2 small centering rings, one of which was positioned right at the end of the clip, so there wasn't really room to strengthen the tube under the clip unless I sanded out the inside diameter of the CR. I thought about just moving the CR down a little bit, but there were a few issues with that too.

In that thread there were several other solutions given to the problem and I considered several, but finally decided on 3) bending the hook backwards so that it didn't go through the wall at all, and installing an engine block ring. I also didn't have a spare engine block ring in my nearly empty spare parts container, but I did have a spent engine that I could cut off a 1/4" piece from the end.



I put glue on the inside of the tube and shoved the engine block ring into place but it wasn't a tight fit. I pushed the block slightly further than flush and when the glue dried I added a lot more to the inside of the tube where it was touching the block. When that dried I was convinced that it wasn't going anywhere.



Then I used pliers to bend the end of the clip backwards so that it would catch on the centering ring instead of the tube wall, clipped off a small piece because it extended past the centering ring, and glued everything together. I also added a piece of tape to keep the hook from sliding forward.



This seemed to solve the problem. Certainly there are better ways, or things I could have done different, but this works and it was fun to do.

I'm definitely going to order some extended engine clips just in case this comes up again. That seems to be the easiest and best solution if you happen to have them when you need them.

 

[RocketManDan]

definitely stock up on motor mount tubes, body tubes etc. You will need them if you decide on building ESTES kits in the future. You'll end up having to replace the inferior quality parts for something better. Quest kits are the same way.

 

[Mushtang]

I think it's a nice kit, but the quality of the parts like most ESTES kits are junk. Nothing fits on the kit as you will soon find out. If you join the three pieces that make the wing, avoid sanding the edges. All you will do is change the size of the wing and getting a square edge is a PITA!!

I love this build so far. And I've loved all the Estes kits I've built so far. There are ways to make sure edges are square when you sand them.

 

[Mushtang]

definitely stock up on motor mount tubes, body tubes etc. You will need them if you decide on building ESTES kits in the future. You'll end up having to replace the inferior quality parts for something better. Quest kits are the same way.

I'm sure I'll end up replacing parts here or there and finding ways to make kits better as I go. I just can't see that I'd blame the manufacturer for a thin walled tube and then turn around and spend a half hour treating and sanding the balsa. It's all part of the fun of building a model for me.

 

[RocketManDan]

I'm sure I'll end up replacing parts here or there and finding ways to make kits better as I go. I just can't see that I'd blame the manufacturer for a thin walled tube and then turn around and spend a half hour treating and sanding the balsa. It's all part of the fun of building a model for me.

Sure you can blame them...they are the ones that make the kit. They know what parts they are using. Poor quality materials = poor quality rocket.

 

[Mushtang]

For instance, the fin marking guide that came with the instructions didn't fit exactly. But I can either blame Estes for printing a guide that is the wrong size, or I can just take a couple of extra steps to overcome this issue. Being new here I realize that it's more likely that I did something wrong to keep it from fitting. Here's the guide taped onto the tube. It was supposed to overlap enough to keep the hatching from showing but no matter how much I pulled and repositioned it I could never make it fit right.



I make tic marks at the fin locations and then turned the guide 90 degrees to see if everything still lined up, and it didn't. The extra length in the circumference was throwing off the lines from the correct place.

I read somewhere about how to fix this so I slid the guide off the tube. Ignoring the printed lines on the guide I folded the guide in half and creased it, then I brought the creases together and folded it again. The guide now had 4 creases that were exactly 90 degrees apart.



When I slid it back onto the tube (not easy to do) I used the creases, not the printed lines, to mark the fin locations. After marking them I turned the guide 90 degrees to check and everything was still lined up!! Hooray, another step down and I'm still having fun.

I used an aluminum angle to extend the marks into lines all along the tubes.

 

[Mushtang]

Sure you can blame them...they are the ones that make the kit. They know what parts they are using. Poor quality materials = poor quality rocket.

I guess Estes just sucks then. Let's hate em!

 

[RocketManDan]

I guess Estes just sucks then. Let's hate em!

LOL Works for me!

 

[Mushtang]

LOL Works for me!

I'm probably going to grit my teeth and suffer through this build thread (and I might even painfully enjoy a lot more in the future). Feel free not to watch and suffer as I'm sure I'll have to make more adjustments before I'm done.

If you want to rag on Estes feel free, but I would prefer you opened your own thread to do so.

Thanks!

 

[Mushtang]

The inner wing sections are made from 3 pieces of balsa edge glued together, so they were sanded to try and make the edges as square as possible. A sheet of sandpaper was laid on the table and the pairs of fins were held together and sanded on edge. Dry fitting all the pieces showed a couple of places that needed a bit of additional work and soon I was happy with the shape.

I used the double glue method to glue the pieces together. Letting the glue dry for about 10 minutes and then more glue added before pressing them together. I kept turning the wings over to make sure the glue that pressed out didn't end up gluing the wings to my cutting mat. After the glue dried I was very satisfied with how they all went together.



To get the wings to glue to the body tube at just the right height a couple of guides were included. These were long pieces of card stock that folded together to make a table for the wing to sit on as the tube was drying.



I used the double glue method again and pressed the wing to the tube the final time using the pencil line up the side of the tube as a guide, then sat it down on the paper triangle to make minor adjustments to make sure the wing was in the correct position. When the first wing dried I put on the second one and used both guides to keep the wings flat.



When the second one dried I added a large fillet to the top side of the wings where they met the body tube for strength, and let it dry for a few hours. When I came back to see it I noticed that the wings had angled up a little bit from the glue drying and pulling on the wings. So I quickly added another large fillet to the bottom side and placed the wings back onto the guides. A few weights to hold everything in place and it was left overnight to dry. This morning the fillets had dried and the wings were back in correct alignment. Whew!

I put the nose cone in place to test fit it. The wings didn't seem to align perfectly with the edges of the cone like I would have expected, they were *slightly* at the wrong angle. For the heck of it I turned the nose cone over and checked it that way and the fit was nearly perfect!! So labeled the top of the rocket on the outside and inside of the tube so I can be sure to have the best fit.



Hey, it's sort of starting to look like something with the nose cone in place!

 

[plano-doug]

View attachment 75223

I put glue on the inside of the tube and shoved the engine block ring into place but it wasn't a tight fit. I pushed the block slightly further than flush and when the glue dried I added a lot more to the inside of the tube where it was touching the block. When that dried I was convinced that it wasn't going anywhere.

When I get a loose fitting ring, I will apply a wrap of kraft paper (brown grocery sack) to it to tighten its fit.

BTW, if yellow glue (wood glue) is used to fill the gap, it will shrink and deform the tube.

Doug

.

 

[Mushtang]

As I was waiting for the glued wings to dry I tackled the job of slicing up the plastic parts for the wings. The jet engines in each wing had an intake cone and a thrust nozzle. They come molded together and you have to cut them apart. There's also a small piece on the back that you have to cut off



I used my hobby knife and removed all flashing from these pieces and the nose cone and then sanded all the plastic pieces to give them a rough surface so the primer sticks better.

 

[Mushtang]

When I get a loose fitting ring, I will apply a wrap of kraft paper (brown grocery sack) to it to tighten its fit.

BTW, if yellow glue (wood glue) is used to fill the gap, it will shrink and deform the tube.

Doug

.

That's a good tip about the grocery sack paper! I probably should have wrapped it with something but this ended up working. I used white glue and tested the whole thing by sliding an engine in place. It fits snug enough and I think it'll work.

I would hate to have used wood glue, have the end of the tube pulled in, and get an engine stuck in the smaller end.

 

[RocketManDan]

You're doing a nice job on it so far

 

[Marc_G]

Nice job. I have two of these stashed away. Im following this detailed thread with interest!

op:

 

[dpower]

Then I used pliers to bend the end of the clip backwards so that it would catch on the centering ring instead of the tube wall, clipped off a small piece because it extended past the centering ring, and glued everything together.

That's a great idea, and certainly solves the problem, without any new parts. Nice build thread.

 

[JPVegh]

This is a great kit! I've built several of these over the years and they have always gone together without issues. The only real problem I've had is with the shockcords that are supplied with the kit, they are too whimpy IMO and the tube doesn't have much room for anything heavier. Still I love this one and think that Estes did a great job on it.

Did you scan the fins and the paper overlays before starting the build? I don't think they're available on any of the plan sites.

 

[Mushtang]

This is a great kit! I've built several of these over the years and they have always gone together without issues. The only real problem I've had is with the shockcords that are supplied with the kit, they are too whimpy IMO and the tube doesn't have much room for anything heavier. Still I love this one and think that Estes did a great job on it.

Did you scan the fins and the paper overlays before starting the build? I don't think they're available on any of the plan sites.

No, I didn't scan them and I probably should before I continue. I saw that the paper had some embossing or something that couldn't be reproduced on a printer, but I'm sure that I'd prefer to have it to re-print if needed without the embossing instead of not having it at all!

I'll scan them asap.

 

[Real Deal]

This was one of my favorite builds growing up. Completed 3 of them... Great thread!
IMO the toughest part was the patience to make sure top and bottom wings are at proper angles.

The other was deciding to paint dull flat black or shine it up!

Can't wait to read more!

 

[RocketManDan]

This was one of my favorite builds growing up. Completed 3 of them... Great thread!
IMO the toughest part was the patience to make sure top and bottom wings are at proper angles.

The other was deciding to paint dull flat black or shine it up!

Can't wait to read more!

I think flat black will make it more stealthy and military and it's easier to paint! I would like to do an upscale of this model.

 

[mwtoelle]

This was one of my favorite builds growing up. Completed 3 of them... Great thread!
IMO the toughest part was the patience to make sure top and bottom wings are at proper angles.

The other was deciding to paint dull flat black or shine it up!

Can't wait to read more!

I thought the hardest part of the build was gluing on the embossed paper skins. Just take your time when attaching them to the airframe.

 

[hornet driver]

Nice so far. I'm interested. I might need to find one of those and do a kit bash. No, No, No, ,,stop throwing the rotten fruit--IT'LL BE GOOD--Trust me-------Really nice so far !!

 

[Mushtang]

No, I didn't scan them and I probably should before I continue. I saw that the paper had some embossing or something that couldn't be reproduced on a printer, but I'm sure that I'd prefer to have it to re-print if needed without the embossing instead of not having it at all!

I'll scan them asap.

I went to scan them last night and they wouldn't fit on my scanner, so I decided that if I eff up royal and had to find a replacement I'd either 1) rely on the good people on these forums to scan theirs and email me the file, or 2) buy another kit. I know they're out of production but there are still a few around and they're not expensive yet.

The more I get done on this kit, the more glad I am that I got it. It's going to look GREAT when finished!!!

 

[Mushtang]

This was one of my favorite builds growing up. Completed 3 of them... Great thread!
IMO the toughest part was the patience to make sure top and bottom wings are at proper angles.

The other was deciding to paint dull flat black or shine it up!

Can't wait to read more!

I'm going to paint it with gloss black so that the decals look good, and then finish it with dull clear coat to give it that military look.

 

[Mushtang]

This next step was a fairly easy one - gluing the plastic pieces into the short tubes to form the nacelles (the jet engines in the middle of the wings). The plastic pieces had been cut apart and sanded in an earlier step so I just put plenty of model glue onto the parts and spun them into place.

I always twist parts with glue on them if possible in order to spread the glue out evenly.

The trick on these is to get the point on the nose cones to be centered. The front plastic piece doesn't fit tight so it's got enough room to point off center pretty easily. It also doesn't have a lip around it that butts up against the tube like the nozzle does, it slides down inside the tube. It's not so much a nose cone as the front of the air inlet. But sighting down the front of it and looking at it from all different angles while making adjustments I think they're in straight.



These air inlet cones are really neat on the actual plane. They will move back and front during flight to keep the air intake for the turbines subsonic, even while the plane was flying above Mach 3.

 

[RocketManDan]

I'm going to paint it with gloss black so that the decals look good, and then finish it with dull clear coat to give it that military look.

That doesn't make any sense ... why not paint it flat black and then dull coat the decals?? Less work same results...but of course if you want to make it hard on yourself