The sanding device for the tube ends doesn't necessarily need a drill press. Sometimes I have to cut some off an already-built rocket. I run that 10" steel-plate-sanding-disc with an 18v Ryobi drill. It's a handful but it can be done!
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For future reference, I glass full length tubes and cut the switch band from the glassed length.
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Steve, forgot to thank you for this suggestion - I ended up doing exactly that by cutting a small length from the payload bay and using it as the switch band.
Nice flight, Jason. Sorry to have missed it (that 15 traffic was a MESS)!
On the "waggle" issue--aside from the wind, of course--I've found that those back row pads can dance around a lot when launching big rockets. My best guess is that the angled deflector catches the exhaust unevenly, which makes the pad want to twist, leading to wobbly flights and worn rail buttons. (Greg Smith posted a launch video to his website that shows the twist happening.)
Lakebed rash sucks, for sure--hopefully after a little fiberglass and paint, you can test the deflector theory on another flight soon![]()
WOW... That is some serious lakebed rash... How many miles did it take to do that???![]()
Since I started taking the deflector off, I've flown lots of Ms in 40-60 lb 5"-6" x 10-12 ft rockets off those pads with no issue. They're heavy and have a nice, stable, wide footprint. The big fins on the Hawk may have been a challenge in the breeze--I bet the pad scooched around a little as it left the rail--maybe keep a set of stakes with the rocket, staking down the pad is less work than setting up one of the uberpadsI don't really know what the max weight those launch pads can handle, but with the large fin area and the high cross winds during launch, I'm curious just how much risk I took with that launch. Do you know what the maximum weight/height rocket the large rail pads in the back should take?
Since I started taking the deflector off, I've flown lots of Ms in 40-60 lb 5"-6" x 10-12 ft rockets off those pads with no issue. They're heavy and have a nice, stable, wide footprint. The big fins on the Hawk may have been a challenge in the breeze--I bet the pad scooched around a little as it left the rail--maybe keep a set of stakes with the rocket, staking down the pad is less work than setting up one of the uberpads![]()
That being said, back in 2013 or so, cvanc did manage to bend the Unistrut leg of one with an N10,000, so I think the upper limit is somewhere around there! (To the pad's credit, his rocket suffered from bad rail button placement that caused severe rail whip, and the leg got stuck in the mud as the rocket turned.)
Yes, the deflector slips out, you just pull straight up--there's a pin on the back that slips into a receiver on the pad. Drop it on the lakebed right under the pad so you still meet the safety code requirementHow do you remove the deflector? Does it just slip out, or do you need to unbolt something? Maybe I can pick your brain a bit at the next ROC launch, assuming the 15 stays open and the rains cooperate...
The upper button was too low on the rocket--way aft of the CG. The rocket pivots around the CG, so any movement as it clears the rail is around that point. The thrust vector also goes through the CG--not through the rail. So, if the forward button is aft of the CG, the rocket pivots into/away from the rail, leading to bad whip.What was the "bad rail button placement" - it was hard to tell the placement from the picture, only the obvious effect.
Ayii, logging in for the first time in a month--sorry for not getting back to you before the last launch!
Yes, the deflector slips out, you just pull straight up--there's a pin on the back that slips into a receiver on the pad. Drop it on the lakebed right under the pad so you still meet the safety code requirement
The upper button was too low on the rocket--way aft of the CG. The rocket pivots around the CG, so any movement as it clears the rail is around that point. The thrust vector also goes through the CG--not through the rail. So, if the forward button is aft of the CG, the rocket pivots into/away from the rail, leading to bad whip.
Sorry we didn't cross paths at last month's launch. Sad it got windybut I still flew one back row rocket. Deflector off, of course!
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I followed much the same fillet approach on my L2 MegaMagg (inspiration from J.Coker)...also seemed like going thru a lot of epoxy.Fin Installation
Once the glass was cured on the booster section, I was able to instal the first fin, which was a little more challenging than I was expecting just due to the size and flexibility of the fins, and the challenge in trying to clamp the large pieces together.
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Adding the fin fillets with that excess sock in the way is going to be frustrating, so I may trim it off and just glass the tail cone separately once its installed [Update] I did remove the excess sock at the aft end. It really was in the way with the internal fillets, which were complicated enough as is.
I let that first fin cure overnight, and installed the remaining fins today. After installing the remaining fins, I noticed that the first fin is not aligned correctly. I tried to pop it off to realign it, but the epoxy had cured and I feared I might permanently damage the motor mount if I forced it, so I'll have to live with the misalignment.
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Once the initial fin attachments were cured, I started doing the fillets. There are 2 external and 4 internal for each fin times 4 fins means 24 fillets. While the rocket is fixed in one horizontal position, I will do 2 external fillets, two internal fillets to the motor, and two internal fillets to the airframe all at the same time, then rotate the rocket 180 degrees and repeat. This way I can do the six fillets that have gravity in the right direction and then rotate the rocket. Even with the fin roots tacked to the motor mount tube, these fins are still loose at the forward end and will be loose until the external fillets are completed.
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Here's the initial round of fillets using an incredible amount of Rocket Poxy (I used something like 350 grams of epoxy just for these first 6 fillets).
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Also, I have drilled the holes for the rail buttons but will wait to install them until I complete all of the fin fillets and do some sanding.
Update 1/15/19: I have completed all of the internal and external fin fillets and have installed the rail buttons. I also installed the aft centering ring with the loc-n-fin notches that mate to the tabs on the aft side of the fins. Once that centering ring (CR3) was installed, I was able to install the tail cone subassembly (see post #5 above) and epoxy it in place at the motor tube and aft end of the airframe. I have left the final centering ring off and have yet to seal up the tail cone.
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Did you ever build/fly an Eggfinder in the Hawk?
I build a simple skid to slide into the RNWS of my stretched MegaMagg (w a lanyard to extract it).
The skid can be placed:
(a) aft of the weight cartridge, with the NC eyebolt fit to the RNWS hatch (a washer stack centers the bolt and fender washers spread the load)
or
(b) forward of the weight cartridge (if that still works for CG) allowing "normal" eyebolt connection.
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