Future build: Upscale Heatseeker

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Pining for the Fjords
Feb 19, 2017
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So with my twin MPR scale models close to wrapping up I'm already thinking about my next project. My current idea is my first true HPR rocket, planned for once I get my Junior L1 cert but still light enough to fly on heavy MPR motors. I also like scale and scale-like models, so gotta factor that in. I want to have an excuse to get Loki gear so 38mm MMT. No crazy toxic things to deal with -> cardboard and plywood. Now that I have access to a laser cutter again complex ply fins are doable, and I'm not a fan of pure 3FNC models, so slightly complex fins it is.

Considering that, I'm planning to build an Estes Heatseeker upscale. I love the look of the Heatseeker but the original kit is annoying- mine lost a fin on just about every flight. This shouldn't have that issue (I hope.)

The current plan is LOC 3" standard tube and 38mm motor mount, putting the rocket at 275% scale. 38mm AeroPack and 1/4" plywood fins and CRs. 3 CRs with split fin tabs- makes it easier to do some amount of internal fillets and/or install rail buttons if I decide to use flanged nuts like I have in the past. If I end up using wood screws and backing blocks I'll just use one tab and "double butter" to try to get some kind of fillet. (Does that even work with Titebond III?)

I also stretched the main BT just a touch- the scale length is 31.75 inches but I'm just using the full 34" to give me some extra stability as well as not ending up with a useless 3" of heavy wall tube. The payload section will stay at the 8.5" correct length.

I'm planning to use a nose cone from PML because it's an actual 4:1 ogive rather than LOC's 3:1, so it's a better scale representation. Yes, I know I added a caliber of tube, so I should take off a caliber of NC. I just think that the NC length contributes more to the overall look than the entire length.

My other idea is to add some kind of adjustable nose weight. My thought is to have a CR in the nose that the bulkhead bolts to and attach washers to the back of the bulkhead as necessary. Sound reasonable?

Recovery will be 5ft doubled 1500lb Kevlar to a U-bolt on the fore CR for replaceability quick linked to 20ft more of the same, with a LOC 36" chute. OR est. weight around 2.5lb. Trying to keep this in the park flying range on a Loki G80LW. Extra credit is a CTI F59WT- probably not gonna happen, but it's worth a shot.

Not shown in the sim are the 1/4" dowels through the bracket sections to simulate rivets and the dowel struts on the fin tips. I'll have to cut 39 pieces of 1/4" dowel... :facepalm:

The build likely won't start for a while, just wanted to get the design out there and see what people think about it.

One other question- what are people using to mount LOC 1010 rail buttons? They seem to come with a bolt, but I could switch that for a wood screw if it would make my life easier.

EDIT: One other question- what do people think about forward fin tabs? It would certainly make the fins stronger but I'd be worried about snagging the 'chute given how far forward those fins reach...
Looks like you've got plenty of volume, nest a laundry shelf baffle inside the fin tips / on top of the roots?
Looks like you've got plenty of volume, nest a laundry shelf baffle inside the fin tips / on top of the roots?
It's definitely an option- the only issue I could see would be that it would make swapping the shock cord somewhat difficult. I guess I could make it removable... Hmm. Have to think some more about that.

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