ESTES NIGHTHAWK BUILD

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Had a bit of a setback while trying to reorganize my workspace by moving kit boxes and supplies. Put my desk lamp up on a pile of boxes to get it out of the way temporarily…and of course it didn’t stay there. It fell over as soon as I turned my back. And of course it landed in the worst spot possible. :facepalm:

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Glue and lay flat with weight, then paper the wing…it will be fine….you know.
 
Started work on the internal canard hinges. They’re flexible aluminum pieces that function as hinges and are sandwiched between 2 layers of 1/16” balsa laminated together. Although the small pieces of aluminum are thin (0.182mm [0.010”]) it was still difficult to glue the upper and lower canard pieces together absolutely flat.

NOTE: I would suggest that you get these aluminum hinges from eRockets https://www.erockets.biz/semroc-hinge-nighthawk-1pk-sem-ah-1/

I used pieces cut from a soda can for this 2nd model and they’re far too thin. When I tried to bend the canard flaps to the required angle, they wouldn’t stay in place—too thin and soft. Had to tack glue the hinges in place. Maybe doubling up the pieces might have worked, or it might’ve ended up being too stiff. Too late now. Much less trouble using the ones from eRockets IMO. They worked.

Since this build has taken so long anyway and pretty much become a labor of love, I decided to make the effort to carve out relief areas in the balsa where the aluminum sheets will go, so that the upper and lower canard pieces will be flush when glued together.

Canard slot.JPG
canard hinge.JPG
 
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I used pieces cut from a soda can and they’re far too thin. When I tried to bend the canard flaps to the required angle, they wouldn’t stay in place—too thin and soft. Had to tack glue them in place. Maybe doubling up the pieces might have worked, or it might’ve end up being too stiff. Too late now. Much less trouble using the ones from eRockets IMO. They worked.

Eric,

Back in the day, when we were young and the Nighthawk was hanging in Hobby Shops, all over America, aluminum cans ( the "Pull-Tab" type ) used to be a LOT thicker than the flimsy ones produced, nowadays !

https://findanyanswer.com/what-type-of-aluminum-are-soda-cans-made-of

Dave F.

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The canard wings are a little tricky to attach, as only the non-movable forward area is available for gluing to the motor pod, and they’re set at 10° dihedral (tips are about 7mm or ¼” higher). Why they need to have a dihedral angle escapes me, but I followed the instructions just in case there IS a legitimate functional reason.

Rather than holding it in place waiting for the glue to dry at what I hope is the right angle, it was so much easier to employ another jig that would do that for me and ensure it also was attached level along the body tube’s longitudinal axis.

canard angle and centering jig.jpg


canard jig front.JPG


canard jig top.JPG

The scrap foam jig fits snugly on the BT, and lining up the vertical line on the jig with the (top) placement line drawn on the tube using the body tube marking guide guaranteed the canards were positioned exactly where they were supposed to be and perfectly aligned.

Maybe got a little carried away with all the jigs, but I really want to get this build as optimal as possible.
 
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Rather than holding it in place waiting for the glue to dry at what I hope is the right angle, it was so much easier to employ another jig that would do that for me and ensure it also was attached level along the body tube’s longitudinal axis.

Eric,

What glues/adhesives are you using in this build ?

Dave F.
 
Instructions note that the canard flap angle should be between 5° and 7° (at least as a starting point). I set it at about 6° using a paper guide that slips over the level part of the wing.

canard angle gauge.JPG

To be continued…
 
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Quick update:
Decided to anchor the shock cord *externally by attaching it to a motor block and threading it through to the outside. The intent is to keep the recovery equipment away from the front of the glider as much as possible by having the ‘chute and shock cord swing away and up to prevent dreaded Red Barons. Hopefully by attaching it near the pod’s CG the pod will come down more or less level and prevent damage to the canard wings or pylon (both of which are not the easiest things to fabricate or repair).

*(Could’ve gone with a rear-eject system https://www.rocketryforum.com/threads/ending-the-“red-baron”-curse.158166/
but I wanted to keep things looking as close to the original Nighthawk as possible).

IMG_7063.JPG

To be continued...
 
On my first glider, the CG ended up being different from where the instructions say it should be, possibly because the laser cut pieces for the fuselage and/or wings were slightly off from the original (here you can see that the end of the fuse sits a little forward of the wing’s T.E. by about 4mm).

CG-1.JPG


The Estes instructions specify the CG location should be 1” forward of the wing trailing edge at the root, while a Nighthawk trimming article I read locates the CG at 0.9” from the rear of the fuse based on the aerodynamic coefficient and maximum glide duration of the glider.

My prelim trimming tosses put it at 0.75” forward of the wing’s T.E. at its root. Not totally unexpected, as the Estes instructions mention the CG location may be different based on things like the final airfoil and finish of the glider. I’d also add that the density of the balsa fuse and wings and density distribution also makes a big difference. My glider only required 1.14 grams of nose weight to get a nice flat glide.

For my 2nd clone, I decided to make the end of the fuse go all the way to the wing’s trailing edge where they join, by sanding off the front edge of the wings where they come to a point. This seems to more closely match the illustrations in the original build instructions.

CG-2.JPG

CG-3.JPG

Should be interesting to see where the CG ends up with this one, since it uses a more traditional airfoil and the wings are just a tiny bit further forward. My guess is that the CG will end up having to be a bit further back than the first glider because the wing’s leading edge on this second one is a bit thicker (so heavier), biasing the overall weight toward the front.
 
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Had the chance to spend some time trimming the glider this a.m. before the rains moved in.
The CG did move back. It’s now only 9/16” from the wing’s T.E. at its root, so about 3/16” further back. Not a whole lot, but just enough to give the glider a nice flat 25’ trajectory when it caught the 5mph breeze blowing today. Interestingly the required nose weight was 1.25g, hardly any different from the first glider.

It has a tendency to veer very slightly to the right though, not a bad thing since that’ll make it circle the launch area. Instructions mention that the angle of either wingtip panel can be tweaked by heating it to soften the glue if it has what it describes as a “severe turn” (which it doesn’t) so I think I’ll leave well enough alone. Don’t want to risk breaking anything. Overall it has a surprisingly nice glide despite being a somewhat heavy-ish glider (21.2 grams).
 
I usually tissue my gliders for strength, but I decided to forego that this time in favor of keeping the weight down. Instead it got 2 coats of homemade sanding sealer, which pretty effectively protects the balsa from the intense summer humidity here in the south while also adding rigidity and strength to protect it from the usual dings, dents, and chips that crop stubble and rocks can inflict on soft, unprotected balsa.

Color was added with permanent markers. Also thought I'd treat it to some decals since it IS my all-time favorite glider after all...and to accentuate those sexy lines.

I’m quite happy with the way they turned out. I got to re-experience the glider of my dreams from 54 years ago, and do a better job of bringing it to life than the first time (along with a backup should I lose my primary flyer). Can’t get any better than that.

Would be great to see someone do an RC Nighthawk upscale. (Tom @Tab28282)?


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Eric,

That looks AWESOME !

If it were me, I would have continued the color scheme of the glider on the Pop Pod . . . But, that's me.

I'm looking forward to flight pics & report !

Dave F.
 
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Anyone know if the Nighthawk is susceptible to getting its wings cooked by the exhaust wash?
Since I never recovered my original, I have no idea if I need to protect the area between the wings.
 
Anyone know if the Nighthawk is susceptible to getting its wings cooked by the exhaust wash?
Since I never recovered my original, I have no idea if I need to protect the area between the wings.


Eric,

I never burned one, BUT I did get an accumulation of exhaust residue.

Some metallic HVAC tape should protect it.

Dave F.
 
Not sure how much collectors are willing to "invest"part with these days, but at that price I think it's definitely going to be a long-term investment.
I agree with you and look at the prices that people pay for stuff on ebay.
 
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