Talon 1.3 - a downscale of GLR's Talon rockets

Picked up some nose-cones and BT-56 tubes from Excelsior Rocketry, so I thought I'd try my hand at a down-scale of this beautiful bird. I thought I'd name it "Little Claw" as a smaller version of a talon, then realized that Wildman also has Eagle Claw, which is a very similar rocket, so perhaps I'm just aping both...

It's a slow process, but I'll try to post periodically, especially with a finished product.

OpenRocket file:
View attachment LittleClaw-DEF.ork

I originally thought I'd put it together on standard 18mm LPR engines, but simulations show that a 24mm motor would be so much more fun. So... 24mm it is.



Planning to use a Semroc baffle set, here's hoping for the best with it (haven't used them before, but hear lots of good things about them).

built up the motor mount already. Engine hook and the MMT ring which holds the engine hook in place came from a Vagabond kit that I'd stolen most of the parts from for other builds. I hear lots of good things about this kit... someday I'll have to build one.

Shaped and papered fins. No Tyvek on these, just normal printer paper.

The MMT CR's are rather thin fiber-board, but I expect they'll hold up to any type of 24mm motor I can put in there, particularly since they're not crossing a large space (MMT diameter is not much smaller than BT diameter). In any case, I'm planning on TTW fin mounting. This is more out of necessity for the rear fins than through structural reinforcement, though. The design puts the rear fins on the tail cone. Since my tail-cone is simply a lopped off nose-cone, I wasn't really sure that I could attach balsa fins directly to it. So, TTW they became. It's going to be interesting trying to cut fin slots through the plastic... and doubly so trying to make sure they line up with the forward fins.

more to come as it comes!

I'm looking forward to it. Ive had this idea rolling around the brainbox ever since Tim posed the question. Need to get some projects finished before I start another, this will be a great preview.

MMT centering rings were Semroc, series 9 to series 13, so a hair on the large size for my BT50 MMT. I did about one wrap with printer paper and wood glue to snug up the fit. Same type of issue with the ring over the engine clip, but ended up putting 2-3 wraps there... apparently more than was necessary, given how the paper scrunched up a bit when pushing the ring over the top. I probably should have either waited until that paper/glue dried more completely, then sanded down a bit, or used less paper and glue.

I'm trying to figure out whether to put a bulkhead on the down-ward end of the tube coupler and mount the parachute below it (separate at the coupler for deployment) or if it'd make more sense to put it as far forward as possible and pop out only the nose-cone on deployment. My concern is that the parachute or shock cord might get caught on the coupler somehow, thus impairing 'chute deployment. Another alternative would be a pull-out recovery deployment, where chute and cord are stowed forward of the coupler and separation occurs at the coupler (nose cone stays with forward tube). In theory, the forward momentum of the nose cone and tube pulling against the shock cord should pull the chute out, particularly if it's attached to the shock cord relatively close to the body. Anyone have experience with this type? I've only pushed parachutes out of a tube, never tried to pull them.

-e

Fin slots cut in BT and in tail cone last night. The boat tail has been a challenge on this build, and isn't something that I've dealt with previously, so has definitely been a learning experience. For example, after cutting the tip and base off a nose cone with a hand saw, I start thinking about how much easier and cleaner-cut it would be to use a chop saw.

Despite wishing for better resources, I think the boat tail turned out all-right. Fin patterns were printed off PayloadBay.com and transferred to the BT. I dry-fit the boat tail to the end and transferred the fin lines to the tail, then measured 1/16" from either side of the fin line to mark the slot. The curvature of the boat tail makes drawing a straight line down it rather difficult, but I managed a decent, if not beautiful, job that I think will accomplish the task.


The aft end of the tail cone didn't turn out quite as round as I'd expected (nose cones look a whole lot more round before you cut through them). It's possible that some of this may be attributed to cutting slightly off the 90 degree angle that would be ideal, but not all of it. Some adjustments to the cut position were necessary in order to fit a BT-50 MMT through the tail without too much deformation. Also, a slot at the aft end will be cut to accomodate the engine hook


Nose cone and boat tail together. Boat tail is made from a twin nose-cone, of course.


MMT was particularly long for the body tube diameter, so gluing the two together required a nice, long balsa stick. First CR on MMT was inserted (not all the way to the glue) then applied more glue for the aft CR. Glue still looked rather light on the aft CR, so I dripped some wood glue down the rear of the BT, letting it settle on the aft CR. Yes, I usually overbuild things.

Next planned steps will be to ensure the fins will sit flush against the MMT, particularly because the aft fins will ride over the engine hook retaining ring, which is as much as 1/16" higher than the MMT.

Latest work: applied thinned Elmers CWF to the body tube. There were very minimal spirals on these tubes, so I'm not sure it was absolutely necessary, but I hadn't done it before so gave it a shot. So far, I'm happy with the results.

As I mentioned before, the fins needed slight adjustment to sit flush against the MMT:

forward fins required a small notch be removed from the rear.

These now sit flush, as far as I can tell.

I tried sealing the aft edge of the fins with CA. It seems to be relatively sealed, but the fins aren't quite as pretty at this stage. Hopefully everything turns out well enough with sanding and paint!

Fins have been mounted without issue. Again, these were TTW as I didn't want to try gluing directly to a plastic nose (tail) cone. I used the "butter, insert, remove, rebutter and re-insert" technique. Unfortunately, the tube dimensions and the order of build operations prevents inspection of the fin to MMT bond after the fins are in place. I suppose it would be possible to have left off the aft MMT until the forward fins were in place (and assemble the retaining hook, etc afterwards), but the aft fins would be more difficult. The only thing I can think of for those would be to slot the shoulder of the tail cone such that it could slip past the fins after they're glued in place, but the cost to the structural integrity of the tail cone as well as the precision required for doing this suggest against it.


Without visual inspection of the fin to MMT bond, I opted to put epoxy fillets between BT and fin. Nothing major, perhaps 1/8" radius. I mixed up my epoxy with a Popsicle stick, then used it's rounded end for the fillets.


Attached launch lug (going 3/16" so I can launch on my own pad when I feel like it) and cut a small slot in the tail cone such that the engine hook has enough room to flex without deforming the MMT significantly. -that's a disadvantage with using body tubes as MMT's... they're thin enough to flex significantly with external loading.


And now the (nearly) finished product!

Thinking about the forward payload section, I probably would have done this differently, but perhaps it'll hold up as I did it.

The coupler is glued to the forward BT section and two 1/4" balsa bulkheads are glued in position at the aft end. I've screwed a small eye-hook into the balsa. The screw threads are roughly 3/8" long, but don't have very beefy threads, so I have some concern about the nose cone getting launched during ejection. I will add a slug of glue to help make sure it doesn't unscrew.

Actually, I use the same retention method on another rocket with a heftier nose/payload section and it's flown at least a half dozen times with no issues, so given the motor power I'm planning, I think it should be OK. (will post if otherwise!)

Another concern is about the semroc baffle. Well, not necessarily about the baffle, but rather about the included kevlar shock cord. It's roughly 1/32" diameter (or smaller), so I can see it easily causing a zipper if thing go off at the wrong time. I've done my best to recess the loop that will connect the kevlar cord to the shock cord, but this still may be an issue. Any thoughts on how to fix that? In retrospect, I'd probably have attached the shock cord and kevlar line before installing the baffle into the BT, so the link could be further recessed. However, that means that it would be exceedingly difficult to replace, if needed.


Ordered some tiny push-rivets that I'm planning to use to connect the nose cone to the payload bay. These three rivets go through the BT into the plastic of the NC, so should hold things nicely. Use a 7/64" hole. CA around the holes to reinforce the BT is probably a good idea.

I ended up with 100 of these, so I expect that they'll be in my future builds as well...

Very nicely done! Looking good so far. May I ask where you got your rivets? I am currently checking different sources and plan to order a box soon.

Thanks! The real test will be painting, for which I'm struggling with a theme....

Auto parts stores and Ace hardware carry larger plastic push rivets (panel attachment, etc), but for something this small, I had to go to flea-bay. The seller is in China, but shipping was surprisingly fast (~1 week), so I can't complain. Just do a search for "push rivet". Mine were through a seller named "Milancentral", for what it's worth.

Coolness, Thanx!

Edit: Found the ones on flea-bay and will probably order a box whenever I get home to measure the ones I already have. Thanks again, these are exactly the ones I've been searching for!!

Launched this on a D12-5 for the first flight last weekend and it performed beautifully... for the most part. The delay seemed long (long enough to make me worry a bit as it arched over) and when the ejection charge went off, the chute apparently tangled and didn't deploy. Despite this, or perhaps thanks to the soft pumice and scrub brush in the central Oregon desert, the rocket survived the descent with only a slight scuff on one of the forward fins.

Altimiter in the rocket shows 767' peak altitude.

I'm thinking it'll be a great park flyer on some C11's.

Regarding paint, it's coated in white primer at this point, and a white based paint scheme wouldn't look bad (could be very missle-like), but I'm still not settled, so primered, it will remain.

One additional though on the baffle: the shock cord (1/4" elasticized cotton) shows some blackening/scorching, but is really about the same level as if I'd used wadding instead of a baffle, so it seems that the baffle and wadding (in this case) seem comparable.