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Max_Power004

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I am in the process of building my first SR-71 Blackbird. I was doing everything I could to make it perfect. Painstakingly sanding and resanding, sanding sealer, sanding, sanding sealer, sanding. Being very careful that fins are on straight, etc. I wanted this bird to be beautiful, and fly really well too. So I'm putting the shroud on, and it goes on fairly well, a few imperfections, but not bad at all. I glue the last corner of the shroud down, and put the nosecone on. There is a huge, glaring, hideous gap where the shroud meets the nosecone!!! I screwed up!! Ahhhh! Anyone else have this problem? If so, any hints on how to do it better next time. Because there will be a next time, believe you me.:cool:
 

graylensman

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My Blackbird shows the same problem too... but since I didn't put as much effort into it as you, it's not as noticeable :p Don't know what to tell you as a fix.

BTW, that was my third kit upon becoming a BAR.
 

sandman

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Max,

Draw a sketch, turn it into a jpeg and post what you have. Or post a pic.

Don't give up yet...we can fix it...there are enough heads here to figure it out.

I seem to recall the same problem with my Little Brothers anmd we came up with a fix.

I don't remember exactly...'cause it's fixed already. it was something simple.

sandman
 

Fore Check

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If I recall correctly, the actual shoulder of the nose cone is hidden by the "shroud" or body wrap (this "shroud" extends forward of the actual body tube by about 1/2", thus hiding the where the cone actually meets the tube.)

could you try sanding down the actual nose cone shoulder so that the cone could be inserted further into the body tube, thus closing this "gap?"
 

Fore Check

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Is the "shroud" or "wrap" already firmly glued in place? Would it be possible (although very tedious and difficult to be sure) to trim the forward and of the body tube so that the cone could sit closer to the shroud?
 

SecretSquirrel

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Originally posted by Fore Check
If I recall correctly, the actual shoulder of the nose cone is hidden by the "shroud" or body wrap (this "shroud" extends forward of the actual body tube by about 1/2", thus hiding the where the cone actually meets the tube.)

could you try sanding down the actual nose cone shoulder so that the cone could be inserted further into the body tube, thus closing this "gap?"

It's been several years since I built this kit, but if I remember the assembly correctly, this could work.
 

Ryan S.

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I didnt have ths problem, take a pic thought I am sure we coul figure something out as sandman said

The sanding sounds like a good idea but there isnt much to sand if I remember the NC correctly
 

Fore Check

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The current set of nose cones from Estes that come in a pack of 5 for the BT 50 include 3 cones that are two-piece. you have to glue the shoulder portion of the cone into the ogive portion, with a "flange" that inserts into the ogive portion.

Perhaps you could trim off the entire shoulder altogether plus the gap length needed and insert one of these ends from a PNC50 bag (?????????????????)
 

Max_Power004

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Originally posted by Fore Check
The current set of nose cones from Estes that come in a pack of 5 for the BT 50 include 3 cones that are two-piece. you have to glue the shoulder portion of the cone into the ogive portion, with a "flange" that inserts into the ogive portion.

Perhaps you could trim off the entire shoulder altogether plus the gap length needed and insert one of these ends from a PNC50 bag (?????????????????)
OK, you lost me there. But, thanks for all the replies everyone, you guys are great! Unfortunately, I can't take a picture because I don't have a digital camera, and I don't have a scanner either so I can't draw a picture :rolleyes: I like the idea of trimming the body tube and nose cone though, I think I'll try it.
 

Max_Power004

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oops, actually, that won't work. the problem isn't that the shroud doesn't meet the cone, it's that I pulled it too close to the BT. it archs up too much. Here's a very crude drawing using Microsoft paint, hope it helps.
 

Fore Check

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AHHhhhhhhhhhh....

The proposed solution that I presented was for a different problem that I assumed from your original post......


Hmmmmm....

Is it that the shroud is too "tight" on the nose cone, thus the gap is on the "sides"; or is it that the shroud is too "loose" on the cone and the gap is at that "top & bottom?"
 

Fore Check

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Ok, so I opened your Paint sketch (I love that piece of software!)

Anyway.....


is your shroud glued to the "top" of the body tube - relative to the cone when the cone is in place?
 

Max_Power004

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yes, top of the tube, glue goes to about an inch, or inch and a half from front end
 

Fore Check

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Originally posted by Max_Power004
if i pull the sides out really hard it looks perfect:rolleyes:
This indicates that the gap isn't too severe - although severely noticeable to the builder!

So....

How about holding the rocket looking down the tube with the nose cone removed, and the "wings" being horizontal at 9 o'clock and 3 o'clock. Maybe, you cold score the inside of the body tube at the 12 o'clock and 6 o'clock position (from front-to-back) to facilitate this "pulling the sides out", and put enough masking tape strips on the shoulder of the nose cone - at only the 9 o'clock and 3 o'clock positions - to simulate this "pulling the sides out."

You know - force those sides out from the inside, rather than pulling from the outside?

???
 

Max_Power004

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That's a really good idea, but not quite enough, I tried it, it fixed the smaller gap on the bottom, and the top gap is a little smaller, but still quite noticeable, I don't want to put much more tape there, because it feels pretty tight now. I don't know, maybe I'm being too much of a perfectionist.
 

Max_Power004

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I thought about putting a thick line of super glue there, letting it dry (it dries up and get spretty hard) and then painting black over it. I know it's kinda goofy, but it might look better than a gap and it would keep the gap from catching air.
 

Dr. Don

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Check out the recent posts.... Someone posted a camera for sale a couple of days ago!!! Dr Don
 

Fore Check

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What did you glue the balsa (that the "shroud" is glued to") to the body tube with? White or yellow glue?
 

Max_Power004

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Don: Yeah I did see it, I couldn't figure out if it was a joke or not. Very funny stuff either way. If the price is right though.....

Forecheck: Elmer's Yellow wood glue
 

Fore Check

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Well,

I had another idea, but my 8 yr. old son even told me I was an idot after "bouncing it off of him." Sadly, he's right........

Is the lateral edge of the piece of balsa that the shroud is glued to (kinda like the leading or traling edge of a fin, but it's "on the side in this case) exposed?

Could you surgically cut this piece of balsa in half (meaning, if it's a 1/8" piece, you'd be cutting it into two 1/16" pieces) and then pull around, adjust, and re-glue?
 

Max_Power004

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:eek: Yikes, very risky, I really don't trust myself to do that. That's a good idea though.
 

teflonrocketry1

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I had the same thing happen to me when I built this kit! Hold the model over the steam from a teapot so the steam hits the paper shroud along the nose cone seam along about a 1 inch band. Be sure to steam both sides on both the top and bottom shroud at the same time. Don't let the shroud get too wet just very slightly damp. Gently push down on the shroud to "mold" it to the correct shape, insert the nose cone as needed and allow the shrouds to cool and dry.

Hope this helps, this will not be very easy since there is a danger of getting steam burns, warping the front of the wings or tearing the shrouds if they get to wet.

See attached picture to see what my SR-71 looks like.

Bruce S. Levison, NAR #69055
 

mikeyd

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I had a similar problem. I put strips of paper on the inside of the shrouds, until the nose fit properly, then soaked the paper shims, and shroud, with super glue. When dry, I sanded the outside of the shroud down until it was smooth to the nose cone. This does sand through the original shroud, but the lower "levels" of paper and super glue make up for this. Then seal and paint.

Happy Flying.
 

graylensman

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Ah. That was <i>not</i> my problem. Mine fits well in that regard... I think I glued more of the shroud to the wings on either side on initial assembly, thus pulling more of the shroud to the tube/wind assembly.
 

xxxREKxxx

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The SR71 I found in the dump also has a gap problem. It seems that the shroud is just a bit too short for the body tube or the tube is positioned too far aft. This leaves a 2-3mm gap between the nosecone and the body assembly. A little dental work with a Dremel should take enough off the top of the tube and frame pieces to get a good fit. Along these lines, does anyone have any scans of the fins for this thing, all four are missing. (Only if it is out of production, I don't want to violate any copyrights)
Bob
 
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