Exo-Skell build thread

The Rocketry Forum

Help Support The Rocketry Forum:

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
5,737
Reaction score
1,173
This looks waaaaaay to heavy for a C engine. Putting an adapter for a D, but can NOT fit a D directly into the plastic motor mount/fin can. Putting in an adapter that will hold a 24mm mount just below the fin can. Will have it's own fins for stability. I put a 20mm baffle in the 20 mm tube, the baffle will be at the level of the top of the fin can, and will be 3 1/2 inches above the motor block for the D engine. Does this sound like it will work?
 

Rex R

LV2
Joined
Apr 21, 2010
Messages
6,086
Reaction score
140
or one could just use 18mm Ds, like the D10. :)
rex
 

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
5,737
Reaction score
1,173
"Painting"

I tried the paint scheme=== paint on, rub off. Unfortunately I hadn't read the instructions, tried enamel paint, doesn't rub off very well. (Instructions say use acrylic.)

Anyway, never being one to follow instructions, tried a "Magnum Sharpie" (something of an oxymoron, if you look at the pic.) Rubbed off with acetone on a paper towel. Not perfect, but overall I like the look. Still have to go over the "trim" with silver paint.EngineMountD12C6motors.jpgFinsLegUnpaintedPainted.jpgSharpieAcetone.jpg
 

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
5,737
Reaction score
1,173
Appreciate your comments StefanJ. I did indeed see your review (very nicely done.) Since my current original fins remain intact, I'd prefer however to use them.

Also Rex R's comments on using an 18mm D. I didn't know they make 18mm D's. I found some available at Apogee. I haven't "graduated" to composites yet. Probably would make sense, I think I'm going to try the adapter first.

Here are pics of my adapter. The BT-20 fits very nicely in the original motor mount. I put a 20mm baffle I got from Uncle Mike's Rocket Shack (plug for them, good prices, fast shipping, everything I've gotten from them seemed like good stuff--- mainly body tubes, nose cones) The baffle will be about 2.25 inches ahead of the forward end of the D12 motor. Is this far enough? Do I need to coat the inside of the tube and the baffle with anything "fireproof"?

I will put fins on the outer tube for stability (basically will look like a booster, 'cept it isn't.)

StefanJ, your review talked about being pretty tight for the parachutes. I was wondering if, WITH the baffle, I can use part of the (original) lower tube to hold the chutes? I'm probably going to upsize the chute for the lower portion of the rocket, given it will be heavier with the adapter and the D engine. Also will FORWARD sweep the adapter fins. Since the lower portion of the rocket will descend Motor down, the motor will hit terra asphalta first, so hoping the forward swept fins will save the fins from the impact.

The motor mount is pictures with a D engine on the left and a C on the right.

AdapterInnerTubeBaffle.jpgAdapterOuterTube.jpgBaffleInTube.jpgEngineMountD12C6motors.jpg




Member
 

Rex R

LV2
Joined
Apr 21, 2010
Messages
6,086
Reaction score
140
if one wants to try a D10 motor from apogee (which by the way are made by aerotech) I would suggest that you check to see if they will fit your motor mount. the ones I had needed the labels peeled off in order to slide into a Bt20 motor tube.
rex
 

scsager

Slightly burned-out old guy
Joined
Apr 24, 2010
Messages
1,740
Reaction score
53
+1 for a stock Exo skell and a C6-3 (photo Below) . For more power you could try a D10-5 from ValueRockets.com

p10_s_sager02.jpg
 

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
5,737
Reaction score
1,173
ExoSkell Launch2.jpgExoskell Launch Close Up.jpgExoSkellAdapter3.jpgExoSkellCompleteAdapter.jpgExoSkellCompleteAdapter90.jpgOkay, I'll cut to the end so you can see how it came out before you decide if you want to follow the build thread further.
Finished pictures (can someone tell me how come when you rotate a pic 90 degrees it makes it shorter? And more importantly, how NOT to make it look shorter?) Close up of the 24 mm Adapter (which worked great and is removeable), and launch shots.
 

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
5,737
Reaction score
1,173
While others have had great luck with a stock build and C6-3, I was a bit concerned this might "open on impact". Used a standard motor mount from a Custom Rockets Fiesta (got 12 of 'em in bulk cheap, great for cones, tubes, mounts) to BT-50 for the 24 mm D engine.

Put 4 balsa fins on it. No, the fins are not on backwards, wanted something a bit different. The angle at the TRAIL edge is actually QUITE intentional. With the D Engine in place, the engine sticks out the back. Figure this will probably hit Terra Asphalta at a 15 degree angle or less. Therefore, unless it is canted more than 15 degrees at landing, the first part of the rocket that hits the hard stuff will be the engine casing, NOT the fin.

Instead of painting or papering the fins, I used mylar film with white glue. It actually came out pretty well, and I liked the contrast between the mylar shiny "mod" look and the original plastic insectoid Exoskellaton look. The outside of the tube I colored black with a "Magnum" sharpie (sort of an oxymoron, if you think about it.)

The internal tube is a BT-20. Somewhat surprisingly, it fit quite easily into the plastic fin can.

AdapterOuterTube.jpg


BaffleInTube.jpg


FinCanPainted.jpg


FinCanSidePainted.jpg


SharpieAcetone.jpg
 

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
5,737
Reaction score
1,173
IMG_1660.jpgThe baffle I STARTED with was the BT-20 from Uncle Mike's Rocket Shack. After looking at it and some discussions with optimal baffle vent holes, I decided that baffling ejection from a 24 mm engine through a 20mm (actually 18 mm) baffle might lead to problems. So I pulled these out. Then I built my own baffle that I inserted into the 24 mm lower body tube of the Exoskell. I coated it with epoxy. The baffle has three plates, each just greater than 1/2 circle width. The baffle worked perfectly, I had no problems with ejection (both effectively powerful and effectively protective--- although I hedged my bets with three sheets of wadding.)

By the way, you can see the "sharpie" above, again something of an oxymoron. Works GREAT for coloring large areas black though. I have used this on unprepped body tubes (tubes that still have some of the glassine on them.) Wear gloves when you do it until it dries or you'll get branded. Leaves a nice purplish black finish with very little weight. IMG_1664.jpgAlso some pics of the fins as I was mylaring them.IMG_1642.jpg
 

Attachments

Last edited:

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
5,737
Reaction score
1,173
AdapterDiagram.jpgHere is the baffle in place.Baffle in Place - Copy.jpg
 
Last edited:

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
5,737
Reaction score
1,173
I used the sharpie marker to color the background and bring out the "edges" of the molded plastic. Colored it on, then wiped it back with acetone on a paper towel. I liked the way it came out. Only limitation was on the legs, couldn't really get into the creases.

I had initially tried enamel paint, but it would't "rub" off the superficial areas. Might have helped to read the instructions (which say acrylic.) EngineMountD12C6motors.jpgFinsLegUnpaintedPainted.jpgSharpieAcetone.jpg
 

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
5,737
Reaction score
1,173
The Alien guy is one of the fun parts of the rocket. There is a little hinge device, and actually he "flips over", so he is "head's up" relative to the nose of the rocket on launch, and remains "head's up" when the Alien Invasion Pod thingy comes down (which is really nose down.) Instructions don't TELL you there is are little supports built into the plastic pieces. As expected, I put it in wrong and he popped off and was rattling loose in the pod. Had to open it up, figure it out, and stick him back in. ExoSkellAlien.jpgIMG_1626 - Copy.jpgIMG_1628 - Copy.jpg

Designed must have had fun with this, lot of work for a guy that you can barely see through the window. As you will see from the landing pictures, the rotation did work, although he looks a bit constipated to me.IMG_1626 - Copy.jpg
 

BABAR

Builds Rockets for NASA
TRF Lifetime Supporter
TRF Supporter
Joined
Aug 27, 2011
Messages
5,737
Reaction score
1,173
Prior reviews had described a problem that is apparently not unusual on Estes Rockets---- not enough parachute space. This flies stock with an 18" nicely colored Estes Chute for the "Mothership" (the main rocket body) and a 12" for the "Alien Assault Pod" (nose cone and legs.)

Hmmm...... Just something "Wrong" about doing all this work to make something look "alien" and green and yellow and black, with little silver touch ups, then having these colored and white striped chutes with "ESTES" printed on them.

Also, the Estes chutes are kind of bulky, and there is not much room for TWO chutes and wadding in that main body tube section.

So exchanged the stock chutes for custom self respecting black garbage bag plastic chutes (20" for mother ship, 14" for the pod--- were supposed to be 24 and 18 but I must have folded it wrong.) I find it easier to cut an 8 sided chute than a 6 (remember making paper snowflakes at school), so my custom chutes all have 8 shroud lines (which is actually infinitesimally slightly more efficient that 6, but I digress....) Even with the bigger chutes, still fit a LOT better in that space than the stock chutes.

First launch was on D12-5, we had light winds and a 7-8 foot high cornfield just behind the launch area. Angled the rod to make sure, whatever happened , it did NOT land in the corn field (was starting to regret my black chutes! Especially with a corn green colored rocket!)


The adapter worked great, got a straight lift off and ascent. Ejection a bit late (next flight would be D12-3.) Recovery was in the (very immature) soybean field. Two or three weeks later would have been a real problem. As it was, no sweat. Landed about 100 yards from pad, Mother and Pod about 50 feet apart. No damage.

Next flight winds kicked up a bit. Angle 20-25 degree into wind and AWAY from the CORN (RSO had one highly raised eyebrow). D12-3. Weathercocked just a bit. Thought I was going hiking. Wind brought both back, landed about 50 feet from pad. Next time I want to get a good photo of Mom and Pod coming down side by side.

ExoSkellBodyLanding.jpg


ExoSkellLandingPodGround.jpg
 

Attachments

RGInCanada

Well-Known Member
Joined
Feb 16, 2012
Messages
154
Reaction score
2
The weathering (alienizing) is outstanding. This has always been an area of terror for me, and your inspired me to give it a try.
 
Top