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This is Effed Up

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kbRocket

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Effed Up is a scratch build minimum diameter rocket designed to fly high with an Apogee F10 motor.

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Effed Up is a sibling of Eyelash. Many of the construction details are similar. I will use this post to highlight some of the differences.

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Eyelash (left) and Effed Up

I will also use this post to describe what I learned from an original version of the rocket that never flew because it perished during charge testing.
 

o1d_dude

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The third picture explains the GPS.

I wish you at least one successful recovery.

PS. You might want to paint the rocket a fluorescent color to help locate it when the GPS says the rocket is within 10’ of where you’re standing.
 

kbRocket

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A tribute to fallen rockets

Before getting into the details of Effed Up, I would like to post a tribute to two rockets that perished. You may learn a little from my losses.

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The rocket on the right is Eyelash, which is described in another post.

The center rocket was called Gee Willikers. It launched but had a tracking failure. My GPS wouldn't fit so I used a 216 MHz RF beacon. At apogee the signal turned from a beep to a click, which in my experience can happen if the transmitter antenna is damaged. I tracked the click for a while until it went over the hill at our site. Despite searching I never regained signal. Gee Willikers is the only rocket I have left in the sage.

The rocket on the left is the original version of Effed Up. It shattered during a pre-flight charge test. This rocket was designed for rear motor eject with a piston. It had GPS tracking and deployment in the nose cone. The electronics sled was screwed in using a long screwdriver. Here are the parts before and while gluing the body to the nose cone:

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The rocket had a wrap of aluminum foil in the upper end of the body tube that I put there to minimize damage from deployment charges. I included it as a first layer over the mylar/mandrel when I made the tube. The body was made out of just 3 layers of 1.43 oz cloth to save weight. Ultimately this was not strong enough.

Inside the body tube there was a unique piston. The charge went in the top, then an internal bulkhead, and the parachute in the bottom. No nomex required. The piston was designed to transfer the motor thrust to the bottom of the electronics bay rather than the body tube.

The entire airframe with piston was just 26.4 grams and I added 16.1 grams of nose weight (tungsten + glue).

It all looked good until I did a pre-flight charge test and 0.5 grams of powder turned out to be way too much. I should have started with 0.1 gram. The airframe shattered and the F10 motor shot out the back rapidly. It shot so rapidly that 200 lb kevlar retaining the motor broke at a knot.

I decided to rebuild the rocket with a more traditional separating nose cone and no motor eject. I also decided that I could reuse the name since the rocket never launched.

Even if the airframe hadn't broken, I think that the rocket would likely have lawn darted during its maiden flight. During the first flight of the rebuilt Effed Up the F10 motor, which was friction fit using blue tape, got really stuck in the body tube. I haven't experienced that before. I think the case of these long burn motors gets really hot. It isn't clear to me if the epoxy reached the glass transition temperature or if the blue tape melted. Either way the motor was really stuck. I sprayed in high temperature silicone lubricant and I squeezed the tube and prodded with tools for a long time, trying to get the lube up into the bonded region. Eventually I got it free. This would have been bad when relying on motor eject.

Before subsequent flights I used automotive wax on both the motor and inside of the airframe. It was strange to wax a friction fit motor. The friction fit did successfully retain the motors and they slid out post flight without sticking.
 
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mbeels

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The body was made out of just 3 layers of 1.43 oz cloth to save weight. Ultimately this was not strong enough.
The entire airframe with piston was just 26.4 grams and I added 16.1 grams of nose weight (tungsten + glue).
WoW! That is some impressive weight!

I'll be interested to read the details of the second version.
 

kbRocket

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Aft Airframe

Airframe tubing was constructed just like Eyelash, so I am not going to go into as much detail about construction techniques. I made some different thickness tubes with different numbers of wraps of cloth. Ultimately the tubing for Effed Up was wrapped with 3 layers of 3.7 oz S glass and 1 layer of 1.43 oz regular glass bonded with Aeropoxy.

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This time I honed the tubing before removing it from the mandrel.
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Fin stock was made from between 2 and 5 layers of 3.7 oz S glass and two layers of 1.43 oz regular glass. By varying the width of layers, more layers were used at the root and fewer layers at the tip to make the fin tapered.
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Fins were glued on and then tip-to-tipped with 3.7 oz S-glass going half way up each fin and 1.43 oz glass covering the whole fin.

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Because the F-10 has no external thrust ring, I made an internal engine block. It has piece of g10 embedded in it with holes that can be used to attach backup tethers for redundant recovery.

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Here is the complete aft airframe, without final sanding, clearcoat, and polishing.
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kbRocket

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Nose Cone

My nose cone molds aren't quite right for these thin walled rockets because they were designed with a thicker airframe in mind.

I tried a different construction technique with better results than the Eyelash nose cone. Eyelash had a tube glued into a finished nose cone which was trimmed, glassed, and sanded. This took extra work and left a distinctive Honest John shape with no real purpose in an altitude seeking rocket.

For Effed Up I blended a section of body tube into the nose cone while it was created in the mold.
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Above you see the mold, which already has PVA release, and an initial layer of 1.43 oz cloth with aeropoxy. This was laid down first and I let it get somewhat cured but still tacky before adding other layers. A section of airframe was wrapped with blue tape at the aft end so it would center in the mold. The front end was sanded to a taper and the exterior and interior where I did not want expoxy to stick was coated with PVA release.

In the next step I put 2 layers of 3.7 oz S glass onto each side of the mold with Aeropoxy and left some protruding upward out of the mold to wrap around. This is fairly standard construction technique. The cloth had been cut to length so that it would extend about 1/2 inch past the upper edge of the body tube section. I took the inside = upper layer of cloth and folded the back end down about 3/4". Then I put the two halves of the mold together and smoothed it out like normal with a long stick.

Next the section of airframe was pushed inside. Then, I used a small hook to pull up the cloth that had been folded over. I used the stick to smooth out the inside. It sounds complicated, but wasn't bad.

I let it harden with the base down so extra resin would drip out.

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Straight out of the mold it had a little flashing that sanded off easily and was already shiny and the correct shape. It cleaned up well with only light sanding.

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The result is that the nose cone was constructed with body tube sandwiched between the two 3.7 oz layers of S-glass. Strong, correct exterior shape, and the aft end is smooth and exactly the ID and OD of the airframe it was trimmed off.

The tip of the nose was formed with Rocketpoxy and the whole nose cone was finished with clear engine enamel.

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A 750 lb kevlar attachment point and 12 grams of tungsten nose weight were glued in.

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Aside from final polishing and waxing, that's how the nose was made.
 

kbRocket

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Altimeter Sled

Normally I make my electronics bay large enough for the GPS altimeter and antenna. On this rocket I sized the bay for the TeleMetrum and battery, ran the antenna out through the top bulkhead, and used a thick cable tie to provide strain relief so it wouldn't be damaged in flight.

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A slot for the cable tie was created in the bulkhead before gluing together the sled so that the closure would be inside and the rest outside. Holes were drilled in the cable tie so the antenna could be threaded through.

The other thing I did different than previous sleds was creating the screw switch flat and directly on the sled. This worked well. There are fewer pieces to glue on or break off and the extra distance between the screwdriver hole = pressure port and the head of the screw accommodates a little more misalignment.

Here are some construction photos. A paper template is tacked on to aid in making sled holes in the right place.

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Magnets and a small square kept the bulkhead perpendicular to the sled and the tip of a cable tie kept epoxy out of the cable tie slot.

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On one side of the sled a brass plate with a soldered on #4 nut is glued on around a hole that was made with the tap drill. The tap is screwed in through the nut so that threads through the sled line up with those in the nut.

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On the opposite side of the sled a brass plate is glued on with a much larger hole. This ensures that the screw cannot vibrate and make contact.

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kbRocket

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Recovery

The only thing I did different for recovery in this little rocket was making a tapered nomex/kevlar blend of deployment bag. This saves some space in the nose cone and reduces the weight of the recovery system.

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An 8" hexagonal parachute was used.
 

kbRocket

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Motor Prep

The F10 motors had the powder dumped out and the hole was plugged with epoxy to prevent any gas from reaching the electronics.

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A tailcone was created using shells of fiberglass molded around blank and slices of a tube made out of JB quick weld made around a drill bit as a mandrel.

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I tried two methods of making the fiberglass shells. Vacuum forming and also simply wrapping peel ply and saran wrap around the blank. Both worked but with the vacuum method it was easier to remove the blank.

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With the shape of this motor only about a 1/8" thick JB weld ring was used inside the tailcone.

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After gluing and sanding, my daughter gave me some old nail polish she doesn't like to test as a finish. For those of you dying to use the same color on your tailcones, it is "Aphrodite's Pink Nightie"

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Unlike the Eyelash tailcone, these survived without damage on all four flights. This is because little material protrudes beyond the nozzle. The tailcone is missing on one motor in the picture below. This was the first motor that got stuck. The tailcone survived the flight, but was ripped off with channel lock pliers during a removal attempt.

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The finish did suffer some damage. You might try high temperature nail polish.
 

kbRocket

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Flight

Effed Up was launched four times over two days last weekend at the Oregon Rocketry, OROC, Rocketober launch.

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Final dimensions on the rocket were 29.5 mm diameter, 395 mm long. There were no changes between each of the four flights. Launch mass was consistent, ranging from 191.3 to 192.1 grams. This is a little heavier than optimal. There was some surface layer wind at times and it took four flights to get a good vertical launch from the tower.

The tower was located at the high power pads. It was strange launching such small motors from there. Compared to other rockets, these flights were amazingly quiet. The rocket just levitated with a little hiss and silently disappeared.

















GPS altitudes: 7470, 7008, 7290, and 7989 feet on an Apogee F10.

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Flights came down between 1 and 1.5 miles away with main at apogee and ~30 ft/second descent rate. Thank you GPS.

The tether on all four flights was twisted. I haven't had this problem before. Eyelash didn't do it. I'm surprised because I thought with this relatively slow descent rate that the rocket would hang down and not twist. Dangly stuff protruding up from the bulkhead (cable tie, apogee and redundant apogee igniter wires) did get caught in the tether and may have helped encourage twisting.

The main parachute, which was on a ball bearing swivel, worked perfectly and did not have any twists in its shroud lines so descent was according to plan.

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So that's Effed Up.
 
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neil_w

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8000' on an F, not too shabby! What's the F altitude record anyway?
 

mbeels

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8000' on an F, not too shabby! What's the F altitude record anyway?
It looks like it is higher than the Tripoli and NAR records. I don't know what the NAR divisions are, but 2435 meters is higher than every other "F" altitude record that I see! Maybe there are other particulars of the rules (such as approved altimeters and what-not), but just in terms of altitude, it looks like these Effed-Up flights were higher.
 

kbRocket

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Charge Test

Earlier I mentioned that the original version of this rocket perished with a charge test that was larger than is desirable. I started testing this one more conservatively. I started with 0.15 cc = gram of 4f bp in the fingertip of a glove. I used one nylon #2-56 screw to hold on the nose cone. The shear pin is probably overkill, but I have had difficulties getting consistency on friction fit nose cones.

0.15 g only made a tiny click and the nose cone didn't come off. Next I went up to 0.25 g of powder and it seemed too violent. I backed off to 0.2g and it seemed pretty good. Here is a video of 0.2 g at regular speed and slowed down. Lightweight components move pretty quick.


















All four flights of the rocket used 0.2 g as the primary and 0.25 g as the backup charge.
 

n27sb

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Way to go, Nice scratch built rocket, Congratulations
 

watheyak

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Huge congrats on the two new records posted to the Tripoli record site! It's a huge amount of work to set a record and it's great to see more people working hard to push the hobby. Well done!
Hey nice! Congrats!
 

mrwalsh85

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Congratulations! It's impressive how much fun you can have with the little ones. I've been considering playing with the smaller ones - we have a field good up to 14.5k - why not see how high I can go with smaller motors?

Enjoy seeing your name up there, and don't stop pushing the envelope!
 
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