SpaceX Falcon 9 and Falcon Heavy builds

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afadeev

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With the SpaceX in the news launching Bod and Doug to the ISS, it seems fitting to build SpaceX rockets this weekend.
As it happens, I have had two sitting in my build pile: Falcon 9 from SpaceX, and Falcon Heavy from Dr. Zooch.
The could hardly be more different, as the pics below will illustrate.

SpaceX Falcon 9 kit is an almost crude, almost RTF kit:
SpaceX Falcon 9.jpg

Dr. Zooch's FH kit is pure tube and balsa heaven, but will take more care to assemble:
Dr. Zooch FH.jpg
 

KILTED COWBOY

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Keep an eye out.
Boyce Areospace has the Dragon capsule and some parts for the booster
I would not be surprised if they come out with a builders kit soon.
I emailed them and begged for one.
Their other manned spacecraft kits are fun to build
 

afadeev

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Since you have to start somewhere, I will roll with Falcon 9 first.
Partly because it's in the news, partly because it should be quick and easy.

The background - this is the kit one used to be able to order from SpaceX directly for $35 + shipping, but it has been discontinued some time in 2019. I'm not surprised, since the quality of the parts could be seen as an embarrassment for the brand. It can now be found on eBay for somewhere between $50-100.

Let me explain.
The tubes are of post-office mailing container thickness and quality. Cuts are rough, inside surface is uneven, and the coupler is far too short: 2" total, offering 1" shoulder on a 1.75" diameter airframe. Care will need to be taken not to glue it crookedly, as it fits into the airframe loosely, at best.
SpaceX tubes.jpg

24 motor mount is a plain vanilla Estes style, with a nice plastic 9-engine faux-engine-nozzle enclosure.
There are two problems with the MMT:
1). There is no cut-out in the decorative faux-nozzles for the motor retaining hook to retract properly - would need to be fixed with a hobby knife.
2). If you want a proper screw-on retainer, the decorative faux-nozzle piece will have to be sacrificed, and it leaves no room for both the threads and the cap to fit inside of the plastic piece.
SpaceX MMT.jpg
Since I don't intend to push the performance limits with this kit, I will go with option #1.

Lastly, the paper wrap came pre-glued onto the airframe, and appears to have been applied by a 3-year old.
There are numerous air bubbles underneath the wrap, and it was glued crookedly:
SpaceX tubes 2.jpg

Other than that, it's all good.
 
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afadeev

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Keep an eye out.
Boyce Areospace has the Dragon capsule and some parts for the booster
I would not be surprised if they come out with a builders kit soon.
I emailed them and begged for one.
Their other manned spacecraft kits are fun to build
Thanks for the heads up.
I will probably snag that kit, when it becomes available.

The ID of the SpaceX airframe is 40mm, so close to BT-60, even though OD is 44mm, or +2mm thicker than a BT-60.
So buying a Boyce nose-cone is an option, though it wont fit all that well: https://boyceaerospacehobbies.com/c...oducts/spacex-dragon-ii-nose-cone-upgrade-kit
 

afadeev

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Since the coupler is way too short (less than 1 caliber on each end), it helps to align the two airframe pieces while you glue them together:
SpaceX airframe.jpg

Shock cord is to be attached to the airframe paper tube with an Estes-style tri-fold, which sits on top of the 23" long two-piece airframe.
However, the shock cord itself is a combination of a 19" long Kevlar cord and 16" long thin elastic cord. That's both too short and too flimsy for my taste, and I've sworn off using elastic cords on rockets long ago. The few times I had neglected to uphold that promise, things ended badly (with elastic braking, nose cone floating away and airframe coming in ballistic, links to be added later).

Thus, I went with 3x the airframe length of Kevlar cord (from my Kevlar cord spool, bought off Amazon) or 69" of Kevlar, and threw away the elastic.
I briefly considered anchoring the shock cord in the airframe coupler, or even the MMT, but saw no need for that on a low-power rocket.

As designed, the lower portion of the payload fairing is to be glued permanently to the airframe, and the shock cord is to be tied to an X-brace inside the lower payload fairing section. During ejection, the airframe separates between the lower payload fairing transition and the rest of the payload fairing structure. Some folks have reported issues getting the chute to deploy with this arrangement, as the ejection gasses first push the chute into the fairing, before the shock cord tries to yank it back out.

I'm thinking of sealing the payload fairing, and leaving it for the purpose of housing an altimeter or GPS tracker, and separating the airframe below it.
Option 1 (stock):
SpaceX Option 1 - stock.jpg
Option 2 (preferred):
SpaceX Option 2 - preferred.jpg
 

kuririn

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The Space X model is a good flyer. The original issue had a body wrap that the buyer applied themselves. Even seasoned master modelers had trouble putting these on. Subsequent kits had pre-applied wraps.
The newer erockets DZ Falcon Heavy kit has laser cut fins. The original DZ kits had flame fins cut from a template that was provided. A bit of a challenge.
Haven't maidened my Falcon Heavy yet. I'm concerned by the large length of trailing fins exposed to the exhaust plume. Don't see how they cannot get scorched.
I think I'll wait for your flight report first. 😄
BTW in addition to the Dragon capsule Boyce has upgrade parts for the Falcon 9 including 3D grid fins and landing legs.
Laters.
 

ToneDeafJunior

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You are correct. The exhaust from the motor does discolor the fins, but I have flown my F9 more than 15 times and the fins have not begun to melt. They are not as pretty as they once were, and I agree, a new design would be warranted. I believe SpaceX designed this kit this way so the rocket could stand on its on without the motor retainer getting in the way. Overall, a great kit and yes. It's a great flyer. I always take this one when I go to the field. And the Estes V2. Both are super reliable.
F9 Fins.jpg
I look forward to the Zooch build.
 

kuririn

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Hey Chuck,
Actually I was referring to the Zooch Falcon Heavy, not the Space X Falcon 9.
Take a look at how far the flame fins trail behind the motor and how close they are:
0531200636[1].jpg
 

afadeev

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It took a little bit longer than one day to complete the kit, net of a couple of improvements. If I had stuck to the instructions, it would have been finished in a couple of hours.

Once the fin-can is dry-fitted, you realize three things:
  1. Full half of the front length of the fin root is unsecured, and is hanging loose. Positioning it perfectly inline with the airframe will be a challenge.
  2. There is no way to access the fins and repair/replace them after the fin can is glued. The top centering ring locks them in place, and prevents extraction after initial assembly.
    • You might be able to Dremel out the roots and re-fit replacements down the line, but it will be messy.
    • The reason I care about this scenario is because I've flown plexiglass-finned rockets before, and those fins are anything but sturdy.
  3. Even after the fin-can was glued to the airframe, the front of the fins would easily move sideways 1/4".
SpaceX fin can.jpg
I really didn't feel good about that amount of fin root instability, and decided to epoxy fin-fillet all of the fins.
I did not trust masking tape to not mar the clear fins, so used Tamiya masking tape on the fins. Blue masking tape on the body:
SpaceX fin fillets 2.jpg

BTW, kit instructions calling for 5-minute epoxy are really not helpful.
You really want to pre-glue all 4 fins at once, then glue the motor mount in place, then test fit everything onto the airframe and adjust the fins-to-body angles for each fin. There is absolutely no way to complete all of the above tasks before 5-min epoxy would harden, so I used 30-minute epoxy instead.

Then, I finished painting and assembling the functional payload fairing assembly.
I fabricated a round balsa-wood "bulkhead" to block the bottom of the lower fairing cone (no pics, but can take them if someone cares), papered & CA-ed it for strength, and epoxied it in place. Then drilled two holes and tied the shock cord to the bottom of the payload fairing bulkhead. The other end of the shock cord was 3-fold-glued to the inside of the airframe tube.

To securely open and close the payload fairing, I tapped two 4-40 holes for nylon screws through the shoulder of the top of the fairing / nose cone. This piece will now be removable. A pre-cut chunk of a pool noodle fits right in, and will keep the altimeter from bouncing inside the usable payload fairing:
SpaceX payload.jpg

These are the pics of the completed rocket from a side, and the top:

SpaceX completed side view.jpg
SpaceX completed top view.jpg


It looks decent from 3-feet away.
The second picture gives away pre-installed wrap's factory crookedness and uneven glue application below the surface.
Anywhere closer than 3-feet away, and you can spot a lot of cosmetic issues with the kit, all courtesy of lousy factory quality control.

However, she will fly, get dirty, pickup new nicks and bruises.
Final weight came came in at 229g / 8 oz, and that is inclusive of all the modifications, fin fillets, proper nylon chute (plastic one from the kit went into trash), Kevlar chute blanket, and chute swivel.

She sims to 400 ft on D12, 777 ft on E12, and 1542 ft on F39.

This one is done, and I'm ready to move onto the next kit.
 
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afadeev

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Speaking of the next kit, Dr. Zooch's FH balsa heaven, we fill the balsa in with wood filer, sand it smooth, then CA it for stength.
In that sequence, right?

(It's been too long since the last time I worked with balsa)
 

OverTheTop

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neil_w

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Speaking of the next kit, Dr. Zooch's FH balsa heaven, we fill the balsa in with wood filer, sand it smooth, then CA it for stength.
In that sequence, right?
Are you talking about fins or nose cones?

For fins, applying CA after wood filler would be an unusual step; I don't think I've ever heard of anyone doing that. Although for those flame fins maybe it would protect them against the exhaust blast a bit, dunno.

If extra strength is needed then papering is usually the way to go, maybe not for those flame fins because even I would now want to try to trim those things. :)
 

afadeev

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Are you talking about fins or nose cones?
Nose cones.
I have a couple of rockets with balsa nose cones, and all are showing significant damage on the balsa surface. If not from flying and bouncing off the ground, then from transportation.
So I am definitely interested in hardening the outside layer of balsa to make it more durable.

For fins, applying CA after wood filler would be an unusual step; I don't think I've ever heard of anyone doing that. Although for those flame fins maybe it would protect them against the exhaust blast a bit, dunno.
Those flame fins will definitely get CA-ed, for sure, for flameproofing.
I will try to avoid papering, since adding more weight far aft of the rocket would be detrimental to stability.
 

neil_w

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Nose cones.
I have a couple of rockets with balsa nose cones, and all are showing significant damage on the balsa surface. If not from flying and bouncing off the ground, then from transportation.
So I am definitely interested in hardening the outside layer of balsa to make it more durable.
Ah. Well, you can do it either way. My general approach is to sand the nose cone pretty smooth, then apply one or two heavy coats of thin CA, sand as smooth as possible, then apply a finishing layer of wood filler. My reason for doing it like this is that I have never been able to get a perfectly smooth finish after sanding the CA.

That said, you can certainly apply CA on top of the wood filler. A *thin* layer, in fact, is very easy to apply smoothly (e.g. with a cotton swab), but I don't think that thin layer provides as much hardening as you want.

So my preferred approach is to harden the nose as much as I can, then use filler for final smoothing (followed, of course, by filler-primer).

Other folks may do things differently but that is what works for me.
 

rklapp

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Speaking of the next kit, Dr. Zooch's FH balsa heaven, we fill the balsa in with wood filer, sand it smooth, then CA it for stength.
In that sequence, right?
(It's been too long since the last time I worked with balsa)
I just used wood filler on mine. I used CA on the landing feet because I was worried about warping the cardboard with glue. However, the CA reacted slightly with the clear lacquer I sprayed on a couple days later. I'm not sure why you'd need to strengthen the detachable nose cone with CA unless you're worried about lawn darting. I believe the flames are plywood iirc and held up really well. The paint at the bottom of the tube had small heat blistering but that just makes it look cooler. The flame tube is detachable, so added extra tape to the inserts. Don't want to lose the flame fins during flight. Not sure yet if I want to epoxy the tubes into place.

 
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