Upscale: Estes Scorpius

I've had this bookmarked over on "Ye olde rocket shoppe" and decided to play with the numbers. Didn't take long to realize that I did indeed have enough tubing here on-site so I decided "what the hey..."

Currently I'm working on the drawings, but already have some RFQs out to get an estimated price on some parts so I can figure this out. I plan on working on this in the evenings or as a "break the monotony" as I get back to the job hunt. I hope to use as much material as I can from my personal inventory. Some things I want to send out for precision work (such as the pod centering rings, etc). I don't think those will be too bad though.

So here we go...

Specs:

Overall Length: Approx 65"
Main Body Tube Dia: 4"
Pod Tube Dia: 3"

Motor Mount: 54mm

All fins will be 1/4" Plywood.

I am debating on a dual deployment setup, but I know that the design could lead to tangles, fouled chutes, etc... Perhaps I can try an Archetype Rocketry "Cable Cutter" with the av bay in a single location. I don't intend to push the envelope with this bird, however it'd be nice to have the dual deploy option for locations that feature unique recovery obstacles. I would like to be able to fly with "Let's just toss it up" motor ejection option, but need the flexibility so I may just completely close off the motor tube and go electronics only. Plenty of time to mull that over while I figure out the rest of the logistics. I will also need a custom nosecone as there are no elliptical nose cones available in 4" so I will need to look into alternatives....



Feedback, constructive criticism, etc. is appreciated!

View attachment scorpius.bmp

The Archetype Rocketry cable cutter is the bee's knees, I'm switching all my DD rocket to this configuration. Cuts the complexity of dual deploy in half. Looks like a cool project, I will be watching.


TA

So how does one obtain one of these Archetype Rocketry cable cutters. I see them for only $25 but they are sold out everywhere. I want one to play with.

Never mind I found them and have two on order.

It may be longer than you are looking for, but Estes sells the nose cone for the PS-II Mega DRM.....

I agree. I have to say that I'm "hemming and hawing" at the moment, as the fins are very prone to breaking. Trying to figure out the best way to keep from happening.

Mike

OK, so it's been a while since I started this project. Most of the time was spent doing the design work, making sure the numbers matched up properly, etc. Here's a 2-d view of the rocket as seen in AutoCAD - my modeling software of choice.



I wanted to use up some of my inventory and spend as little $ as I could, so I managed to find some 3" scraps of Red Arrow Hobbies tubing left over from my L3 project as well as a few fresh tubes of 2" LOC tubing. I also had a few 4" PML tubes. Based on this, I created a excel spreadsheet which scaled all the dimensions accordingly based on body tube diameters, and I could've done a 2" dia, 3" dia, or 4" dia thanks to the fact that Estes' tubing tends to scale (BT5/20/50) well. I decided to go big, besides I had enough 4" tube!

I decided I want to make this thing dual deploy, so I needed an avionics bay. I am planning on using the Archetype Rocketry cable cutters for dual deployment. I may even see if I can't install a camera on this thing!

Nat at UpscaleCNC cut these parts for me and had them shipped to me. These are the parts as I received them. I saved a bit of money by providing Nat with a *.DXF file which he was able to import into his program for the CNC Router with minimal modification. I also accepted the parts straight off of the mill - I happen to have a belt/disc sander in my shop so that was not a concern at all for me. You can see what type of work is required when they come off the machine.



So, now I get to make chips/dust! Had to cut all of the tubes before I can really do anything. It is my goal to have a "kit view" of the whole project before I actually start building... However I don't know how long I can resist the temptation to mix epoxy! I needed (4) 3" (outer) tubes and (4) 2" (inner) tubes.



- A testament to how well UpscaleCNC does. I provided Nat with actual dimensions (I measured ID's with calipers during the design stage).


- I wanted to get an approximate idea of how big this thing will be... COOL!

So, I started off by fiberglassing the main airframe. Standard procedure. Nothing fancy.

I decided to tackle the pods and fiberglass them. I used a lighter weight 'glass on the upper pods (which I will slot later), and a heavier weight on the lower pods. These will take quite a bit of abuse.

On the lower pods, I had to slot them as the actual fins traverse the full length of the pod. This means the tubes will be cut then sandwiched in place. You can see what I did below.





Parts after cutting. You can see how they are different. I had to remove a slice (totaling the thickness of two fins) from the narrower part.



Mocked up. Should fit nicely.



Parts all 'glassed up. Excuse the nasty workbench.



I also epoxied the CR's in place last night. Tonight, I epoxied the lower main airframe fins in place. You can see how I kinda cobbled it all together. The bungee keeps the fins tight against the airframe.

Next step(s) are to drill the CR's for the pods and epoxy them in place and then epoxy the fins in place. After that's done, I need to source some 1/4" Carbon Fiber rods or tubes for the pods before I can apply the pod skins.

I did see some 1mm thick .210" OD CF tube at the hobby shop yesterday. At that thickness, it was still pretty rigid. Not sure if I'll go with tube or rod still.

Any thoughts? I need for it to be durable, but have some give as to not snap if it hits something upon landing.

I'm in...

Was feeling a bit antsy this morning, so I put the motor mount aside after confirming the epoxy was well cured.

First step was to drill out the pod centering rings as Nat spot drilled them at my request. I used a fresh backer board for each hole, ran the drill at a moderate speed and used a slow feed rate, but not too slow that it could bind up. The result is seen here:





Marked the inner tubes of the Pods for alignment (I marked the CR's with alignment lines as well) and the tape is a barrier to keep the upper CR from slipping down. This ensures that it will be in alignment.



CR's epoxied in place.

I also epoxied two ribs onto the main MMT. I mainly use them for alignment but they also give me some peace of mind.

The next step is to attach either the pods to the spanning fins or the outer fins to the pods. I'm thinking I will do the pods to the spanning fins, then develop some fixtures to keep the fins aligned as they are epoxied in place.

Gonna try and order that CF tube/rod today for the pods... Maybe I'll get it Monday.

Mike

Go Mike go!! op:
Jeff

So, an update!

I checked the fit of all components before going any further. Looks good!


I then epoxied the lower pods to the main fins and used regular epoxy to "wet" the mating parts, then added silica as a thickener for the fillets. Then I came back with some milled fiber to create a fillet.

Next, I had to develop a fixture so that my pod wings would be in the same location every time. I thought about it and had a 30-60-90 triangle laying in the shop... And found a piece of 1x2 which had an angle on it... After toying around, I realized I could run a dado through the 1x2 and then tape the triangle in place. I had to raise the whole contraption up about 1/4" so I found some scraps which I used as feet. Not bad...


Then it was time to attach the pod wings. I used the same thickened process and it worked out well. I would check on each fin every so often to make sure it hadn't drooped or whatnot... Perfect alignment. Looks good if you ask


Next, I decided to sliing some epoxy. Got some fillets in using some thickened epoxy with silica.



I decided to add the forward fins so I found that my table saw extensions nested just fine so I set up a contraption and slung some epoxy.


Dry fit of the forward pods. They should be epoxied on by the time most of you read this.

K'Tesh said:

I'm in...
View attachment 146383

Click to expand...

Yup

Nice! looking good.


TA

Yup ,this is a great build Mike.....beauty !

Those are some very nice looking and well made components.

Hey...where`s those pods ??? LOL

Take care


Paul T

Sorry for the delay, guys...

So, I spent a little time hemming and hawing about what to use for the spars between upper/lower pods. eventually decided on 1/4" dowel rod from Hobby Lobby. I will pin them so that if they ever snap, I can replace them easily.

In order to make them removable, the holes in the pods needed to be clear and sized such that the rods can pass through. I decided to purchase some brass tube, slather in Petroleum Jelly so that epoxy would not bind to them, then glued the lower pod skins on. After everything dried, I was able to get the tubes out with a smart whack of the hammer.





Upper and lower pod skins have been epoxied in place. I haven't cut the fin slot for the inside skin of the lower pod yet as I don't have a dremel to use just yet... But I will! I need to apply fillets to a bunch of places, but probably better off if I wait til I get all the skins applied. I have a lot of sanding to do...



Spars in place... Well, minus two... The other two were not in good condition and I didn't realize that. Oh well, $2 down the drain...

She's getting there.

Now I have one dilemma... I need to determine the Center of Pressure for this beast. I don't have Rocsim and don't feel like paying $80 to upgrade from V4 or whatever I was on before... So all I have is Openrocket.

If I can determine the CP for the original 1:1 kit (I believe there are some files floating around online), can that CP be upscaled as well?

Wow! What a great Build Thread. Lookin' good!

Hi Everyone!

Just realized that this project hasn't moved much other than some epoxy slingin' fun.

The nose cone has been fiberglassed and I've been working on smoothing it out.


I am still unsure of the center of pressure. Does anyone have any suggestions? I purely designed this in AutoCAD based on dimensions from the original model.

Is it safe to assume I can scale up the CP? Unless otherwise told, I won't assume such.

Thanks,
Mike Walsh

I've created a RockSim file for the standard Estes size, plus upscaled it to several sizes. I'm about to build a clone, and an upscale to BT60 to come later. To the point, it appears that the CP more or less scales as you'd expect. I can post the RockSim output when I get home, I don't have access to any of that at work.

Huh, awesome. I was really leery of this but it looks like it may be safe after all.

I'll try and get back to work on this. Would be nice to fly this at NYPower...

Mike

Mike, do you use Rocksim? I could send you the file to upscale if you want. Are you coming to NYPower next month? That's my local club field...

Attached are my Rocksim file images, for stock, BT60, BT70, and 3". You can see the CP more or less stays in the same place, within reason. The variation that does exist is probably due to slight variations in nose cone length/shape, and different proportions of pod tubes to body tube. But its all very much within reason.

Well, it's taken me a while.

The nose cone was custom cut by Nat at UpscaleCNC.

The rocket went through a few moves unscathed.

Now I'm at the point where I need to do lots of finishing. I will have to borrow my dad's palm sander to do some heavy finishing.

I'm hoping Nat can cut me some av bay lids tomorrow and get 'em in the mail for me as soon as possible. I have a launch next weekend and would like to test fly this beastie before I go too far with the finishing process. But for now, I'll knock off all the rough edges and make sure there's no sharp edges that can compromise the recovery system.

I'll go with a simple motor based ejection but use an RRC2+ for apogee deployment. Depending on weight, I'll use a I284 or a J275.

My goal is to have this thing finished for NARAM to have a little fun.

Anyway, thought it was time to update this thread. Enjoy.

Cool looking rocket, good motor choices

Well, the Scorpius flew this weekend. I forgot how fast that I435 is...

Perfect flight to 1,121'. I435 plugged with RRC2+ apogee deploy. The chute I had was the perfect size.

I was certainly nervous, but the flight was pretty good. I will probably do an I284 next time I fly it... Hopefully paint and decals will be done for NARAM!

Well, time to resurrect this thread.

I completed the Scorpius with a bright white paint job and custom decals from Stickershock (down to the Pilot: Mike Walsh detail!).

I flew the Scorpius at NARAM-58 in Walnut Grove. Beautiful flight on a Loki I405 and recovery.... Until it landed. This rocket is ~10 lbs and I brought it down with a Skyangle 60" parachute, right around 17 fps per SkyAngles calculations.



It suffered a body tube fracture just forward of the rear nacelles. The motor mount was still intact, so the rocket remained together.



Fast forward 3-4 years later and I was talking to a friend the other day about cool projects we'd done over the years, and I brought up the injury suffered by the Scorpius. Last night, I got home from work and looked around the shop in preparation for cleaning then the Scorpius caught my eye. Next thing we know, the whole thing is disassembled in preparation for repairs.

First, I made a mark 12" from the end of the body tube so that I had a reference point for the needed length of replacement body tube.

Next, I took a dremel and cut the motor mount internally. Not pretty but we will clean it up later.

Next, I cut the upper airframe so that there was a clean edge to splice up to.



After making this cleanup cut, I set my tape measure on the reference mark made earlier, and took the measurement. I needed an 8-1/4" length of body tube. No big deal, right?

I have a 55 gal barrel full of phenolic body tubes that was given to me earlier this year, and remembered there were some shorts in there. Let's see if I can use one of these so I don't sacrifice a full length tube. Found the shortest one. Measured it. 8-1/4". Well hot-dang, this is coming together nicely...

Now we shift focus to the lower nacelles.

It was my hope to slot a fiberglass tube coupler and then epoxy the whole mess together, and reduce the motor mount to 38mm permanently since it is a good flyer on 38mm I's.

This was not to be the case, as I forgot how I had built this structure.

The fracture was immediately above the forward centering ring of the aft nacelle assembly. Interesting, but also makes some sort of sense. We'll have to keep that from happening in the future.

After thinking about things for a moment, I had an 'ah-ha!' moment. Let's rip out the entire motor mount tube and replace it with a FWFG motor mount tube so that we have a rigid spine through the airframe. Still need to address the body tube, but I'll get to that in a bit.

After much sanding, we are left with a cage assembly ready for a new motor mount tube. By the time I was at this point, I realized I have a spare 54mm FWFG airframe kicking around in the basement.... It's like this repair was intended to be done.



Took the fin can to the basement this morning before heading to work to check the fitment of the FWFG tube I've got and this is what we have.... "Nice!"



So, now we need to splice the airframe.... Grabbed a 4" tube coupler and thought about things for a moment.

I need to measure the length of the cage, but I think I will be comfortable taking a length of coupler tube and butting it up against the forward CR of the rear nacelles and epoxying it to the airframe there. Make the slip-in distance of the aft body tube the same for the forward tube. Shouldn't be an issue, right?

Decided to check a 98mm FWFG tube coupler that I've got to see if it will fit in a 98mm PML airframe tube. No joy. Well, guess we're going with a PML Phenolic coupler tube. how do we ensure this doesn't fracture again? hm...



I think my plan will be to cut 6 ribs to span the length of the distance between the forward CR of the rear nacelles and the rear CR of the forward nacelles, and arrange them around the motor mount tube. This way if there is any stress introduced to the airframe, they should be transmitted to the motor mount, which is now FWFG and will really beef things up.

I also have specific sequence of assembly in mind as the FWFG tube is a bit of a slip fit. I will need to make sure that I have the motor mount centered as close to perfectly on the center axis.

I'm not sure when I'll get to the assembly, but I still need to yank the motor mount tube out of the forward nacelle CR/Fin cage, do some minor sanding/prep there, then I can start reassembly.

I'll probably need a little nose weight now that I'm adding this weight to the rear. But that's OK. A J90 ought to do nicely. I don't want to get much more altitude than 1-1.5k feet. If I'm going much higher than that, I could be stressing the fin structure a bit much.

I'll try to keep this thread updated. I'm looking forward to getting this up in the air. This was such a neat project that it would be a shame to toss it in the trash can.

Wondering if maybe a three point external shock cord attachment maybe feasible, one point on the nose and two points on the rear nacelles. The external attachment points could be small and easily hidden when on display. The idea is to have the rocket body hanging horizontally on descent to disperse the impact force a bit.

it’s a beautiful design and a great build!

Thanks. I'm not sure I want to do a 3pt system at this time. There's enough stuff going on with this design that I would hate to introduce more harnesses that could simply foul up.

No movement on this project right now. Getting ready for a launch this coming weekend.

Well, my daughter is finally going to bed at a decent hour (gotta love two year olds). And my wife is finally out of the nausea stage of pregnancy so things are easing up timewise... So I was able to get into the shop last night and do a little work. Ripped out the original motor tube and did some sanding with a flap wheel in the dremel with a flex cord. Need to get a new dremel flap wheel as I think it is worn enough that it is just polishing the original epoxy at this point and wasting my time.

I'm still debating on using the FWFG body tube or going with phenolic and adding 1/4" spars the full length of the MMT to reinforce the whole thing. I'd hate to chop up a beautiful piece of 54mm FWFG tube to be hidden in this thing. But it is strong(er), so a better option.