SR-72 Darkbird build thread

The Apogee kit my wife gave me for my birthday I started this afternoon. Here is where I left off:



I'll pick it up again tomorrow night. Check out the complete BUILD THREAD.

Very nice. I'm curious how you constructed your website. Do you use any special software ?

Originally posted by samb
Very nice. I'm curious how you constructed your website. Do you use any special software ?

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I've used FrontPage in the past for work, but currently do not own any myself, so I'm using a terribly limited utility provided by my ISP called Trellix. I'm used to it now and am working around it's shortcomings.

The key on any web site is consistency, makes it easy for people to know what to expect from page to page, and my site is pretty much just a build journal.

Glad you like it (the site). Any critiques?

Just out of curiosity, the third 'panel' of each wing has the grain going crosswise rather than lengthwise. Besides the fact that gluing endgrain needs to be pre-glued and sealed, are you concerned about the strength of the wings or their attachment to the BT?

(Great looking model BTW!)

Originally posted by JBeau
I've used FrontPage in the past for work, but currently do not own any myself, so I'm using a terribly limited utility provided by my ISP called Trellix. I'm used to it now and am working around it's shortcomings.

The key on any web site is consistency, makes it easy for people to know what to expect from page to page, and my site is pretty much just a build journal.

Glad you like it (the site). Any critiques?

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Having never built a web site (yet) I couldn't say. I just like the format of pictures with captions next to them to document the build and I was wondering if it was a template from some special authoring software. As far as the build, I admire the clean, straight lines on this bird. Glue management will forever be a challenge for me.

Originally posted by propbeany
Just out of curiosity, the third 'panel' of each wing has the grain going crosswise rather than lengthwise. Besides the fact that gluing endgrain needs to be pre-glued and sealed, are you concerned about the strength of the wings or their attachment to the BT?

(Great looking model BTW!)

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Thanks, I appreciate it.

No, not concerned at all. Everything is being attached with CyA glue, filleted with white glue, those fins aren't coming off. The papering I added triply insures this, I hope.

As for the fin grains, I thought alot about them but once the fin was assembled, it actually makes sense. The long-grain thin pieces up front with the graining running parallet to the body results in a much stronger "piece" since the grain would be too short to offer much if it were going the "right" way. Then, the transitional piece does present the proper grain edge to leading edge, and the final large block at the back is in our traditionally expected grain direction. It really was the right design, I think Apogee got it right.

Using CyA, the root edges really do soak up a lot of it, so you were on the money regarding sealing the edge,

And remember, it's a glider, so it shouldn't really experience high-speed impact landings like you get with parachutes.

I'm interested to know how you get on. I have an SR72 in the "to-do" box and would welcome anything you learn from building and flying it.

Very nice

Looks great

I may need to get one of these sometime - I've never built a rocket glider before

Originally posted by cjl
I may need to get one of these sometime - I've never built a rocket glider before

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I would never have bought this, I habitually skip right over kits described as boost gliders, but now that I'm well into the build, I really like this kit.

Anyone planning to purchase should note: Apogee has announced intent to discontinue this kit this year. Get it whilst thou may.

Thought I was in the home stretch, til I noticed I'd installed the ailerons incorrectly.



So, I'll have to get some replacement material tomorrow to reattach them properly. Any suggestions?

If you're looking for suggestions on removing them cleanly, I've used a scribing tool (sort of like the evil hook the dentist uses to clean teeth) to remove ailerons and such from plastic scale models. It's tedious and painstaking, but accurate and relatively clean if you have something to guide the point. Again, on scale models I use the thick plastic labelling tape -- which probably wouldn't work here as it would most likely ruin the paper.

As far as replacing? I'll leave that to the variety of experts on the forum.

Jerry,

Thanks for starting this build and your build guide while the kit is still available. I, like you, pretty much gloss over anything glider like, as I don't typically fly in a field I would expect a glider to work out well in. But, the look and fit and finish of the kit seems pretty cool and your build guide shows some really good stuff.

I'm going to buy one, I think, as I have yet to try Apogee and like you say, get them while they are still available.

I do look forward to your flight report, but I am also curious if someone can make a reccomendation as to this kit vs a typical 'first' glider. I'd say my build skill level is fine for typical 3FNC's but not nearly as good as a scale model builder.

Keep up the good work!

Sandy.

by Sandy H.
...the look and fit and finish of the kit seems pretty cool and your build guide shows some really good stuff.

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Glad you like it. I'm bouncing around a little in the way I assemble the bird, but the online pics I tried to keep in order.

I'm going to buy one, I think, as I have yet to try Apogee and like you say, get them while they are still available.

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Excellent! Apogee, am I going to get credit for a rush of Darkbird sales? Hehe.

I am curious if someone can make a reccomendation as to this kit vs a typical 'first' glider. I'd say my build skill level is fine for typical 3FNC's but not nearly as good as a scale model builder.

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Hmm, I've built a lot of rockets in the past year, so I'm actually on the hunt for the challenges. Apogee considers this a skill level 4 on their 5-tier system, and it probably it is.

I'm not saying you can't do it, I'm just saying it's going to take some care. There are four fins attached to the outer jet pods, and only two of them are the standard 90 degree angle. The other two are angled. Templates for measuring the angles ar included and made quick work of it, but it really is a higher level LPR. Maybe someone can suggest an easier boost glider to start, but this is my first, too.

Here she is, all repaired and ready for finishing.


I'm not sure how I'm going to paint this baby. I have no decals (pouts at Apogee) and I do have the SR71 from Estes to build later, so it will get the full blackbird treatment.

Attached are some decals shrox had available on Apogee somewhere, but I have no decal making capabilities. So...

Maybe I will see if there are some generic military decals available at the hobby shop.

Watching your build thread with great interest, with an SR72 in the bag. I was putting off buying it, but the OOP warning moved it up on my list. Just curious, what made you feel the fins were frail?

Originally posted by paulk
...what made you feel the fins were frail?

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It took a long time to get the first fin on straight. When done, I stopped and thought about this puppy coming in glider-style and images of fins popping off left and right started to appear....

For some reason, I guess my mind is just odd, the word frail came to mind and I immediately started papering the other fins. For me, the main benefit of papering is to reduce/eliminate grain filling concern, thus reducing the amount of time I spend pressing hard on the fins while sanding.

It seemed like the right thing to do. Frail may have been the wrong word, but it's what was on my mind.

Now that the bird is being primed and I'm sanding the first coat, she feels very solid, so....good build habits will overcome frailty by default, eh?

Meanwhile, good build habits do NOT overcome grandson attack. My 12 month old grandson got ahold of the primed bird and now Im reattaching the top fins.

Hehe. My family didn't even balk when he did it. They just said, "He's a pro, he'll fix that in no time."

4 minutes. Hehe.

I went to hobby shop and found some loose decals from the Revell 1:72 scale plastic SR71A kit. Here's a sample pic from their product:



The Apogee kit calculates out at about 1:92 scale, and the Revell kit is 1:72. I think that makes these decals pretty much unusable, maybe I can get away with some of the smaller detail pieces, but the lettering and such will just be too big. *sigh*

I would REALLY like to finish my ESTES SR71 Blackbird next and display them together with similar markings, but I'm stuck.

Meanwhile, I've collected an AMAZING variety of marking photos from the various birds, no two birds were alike in internal design and external markings. Lots to think about.

can someone tell me how much clay to put in the nosecone?
When i tried to launch this last year, the nose cone popped out and i couldn't find it. i'm just now getting around to replacing it, but i can't find the instructions, and can't remember how much clay went into the cone.

Does anyone know how far it glides

Wow, this got resurrected from the dead.

Theo J. Swank said:

Does anyone know how far it glides

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This is a great kit. It is an adequate glider. If you have a decent softball field size field, and winds under 7 mph, you should be fine. Grassy field definitely a plus, it comes in a little fast and hard. Definitely not a duration competition type glider.

Good luck!

Here's a complete build from my blog, from finish to start:
https://modelrocketbuilding.blogspot.com/search/label/A SR-72 Darkbird
I haven't launched it yet, waiting for a larger field.

Is it worth adding control surfaces to be able to control the glide

And if so has anyone done this?

while I have no remotely CONTROLLED rocket glider experience, having built and flown this rocket (14” long and has a 13 mm motor mount and relatively minimal wing surface area) I don’t think this puppy would be a great candidate for conversion to RC.

just an FYI your pics are not showing up

AfterBurners said:

just an FYI your pics are not showing up

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Yeah, after 13 years it's probably in the Internet Twilight Zone.

Yet another necropost, but while we are on the subject, you can search the forums for a rudder only controlled version of the Estes Skydart.

I think this dark bird may be a little too small, unless you upsize the wings if you wanted to get a good trimmed glide after adding the weight of a receiver and servo, but this is not from personal experience, just a guess. Also, would a 13mm motor still be able to get it going off the rod fast enough if you added that much weight?

My thread on the SR-73 Raven has disappeared. It was a a scratch/clone/upscale of the DarkBird. Not RCBG but big enough to do it easily

But if you really want a SR-71-like RCBG, THIS is what you want


https://dynasoarrocketry.com/

Scroll down to YF-12

Thank You for all these pointers, think I will stick to the traditional flight for this rocket