Teros 4x Upscale build / L1 attempt (lots of pix)

[DaveCombs]

Back in the 80s I had the Estes Teros (EST 1285); I flew it more than any other rocket I had, and it always went up straight and true, and it always came back to me. I especially loved the ramjet nosecone.

So when I got reintroduced to the hobby by my coworker Mark (Loopy 'round these parts) and attended my first high-power launch, I knew what I had to do: I needed to rebuild my favorite rocket, and make it much bigger so I could learn the things that the high-power folks around here know.

Over the last few months I've asked a bunch of questions and received a bunch of help and good suggestions, but what pushed me into it was my Secret Santa present from DanB, a 1:1 scale CAD drawing of my Teros, scaled to 4x. I'll be using this drawing to get the parts and assemble it.

When I'm done, I'm looking at a Level 1 attempt with it as this is going to be a pretty big rocket (the biggest I've ever made, for certain). But for now, I'll be posting a lot of pictures and probably asking an occasional question.

Wish me luck; here we go!

(Just in case you can't see the pictures, I'm having some cable problems that should get fixed within a couple of weeks (or so they tell me). So, be prepared for an occasional outage.)

 

[ben]

Originally posted by DaveCombs
Back in the 80s I had the Estes Teros (EST 1285); I flew it more than any other rocket I had, and it always went up straight and true, and it always came back to me. I especially loved the ramjet nosecone.

So when I got reintroduced to the hobby by my coworker Mark (Loopy 'round these parts) and attended my first high-power launch, I knew what I had to do: I needed to rebuild my favorite rocket, and make it much bigger so I could learn the things that the high-power folks around here know.

Over the last few months I've asked a bunch of questions and received a bunch of help and good suggestions, but what pushed me into it was my Secret Santa present from DanB, a 1:1 scale CAD drawing of my Teros, scaled to 4x. I'll be using this drawing to get the parts and assemble it.

When I'm done, I'm looking at a Level 1 attempt with it as this is going to be a pretty big rocket (the biggest I've ever made, for certain). But for now, I'll be posting a lot of pictures and probably asking an occasional question.

Wish me luck; here we go!

SSSSWWWWWWEEEEEEEEETTT!!!!!!!
I have been awating this thread I can't wait to see this!. Good luck on it. (and gimme pics! )

thanx, Ben

 

[DaveCombs]

Here's what lit the fuse: DanB's drawing. (That's my son RyanCombs hiding behind it.)

 

[DaveCombs]

Here's the motor mount. It, as well as practically all of the airframe, is from LOC Precision. 38mm MMT, LOC centering rings, and the U-bolt for the shock cord. Since my local hobby shop was out of Bob Smith epoxy, I'm using Hangar 9 12-minute just about everywhere. You can also see the JB-Weld at the seams on the U-bolt.

 

[Fore Check]

Alright, bub! Now we're talkin!

How 'bout a pic of that nosecone? I'm assuming Sandman made it....

 

[Fore Check]

Also: Have you built a RockSim file for it yet? I have a method for "building" that ram-jet style nose cone in RockSim. Bruce Levinson (the guru himself) hasn't verified it's accuracy, but it looks good to me.

 

[DaveCombs]

I had a little dilemma when gathering the parts. On the drawing, the body needed to be 40 1/4" long. LOC tubes are 34", so I figured I would just stretch it a tiny bit further by using a LOC 15" payload section, because it gets me close enough to scale, I'd rather not cut any body tubes if I didn't have to, it pushes the CG forward, and it gives me lots of possibilites for the future (e-bay, camera, etc.). (When I ordered my LOC stuff from DiscountRocketry.com, I had my LOC Order sheet handy, but I forgot to take the body tube off the order; I decided to have LOC make me a custom slotted tube for the airframe.) This pic is of the eyebolt in the bulkhead, and then the bulkhead and coupler about to be mounted into the payload tube.

 

[ben]

you have a PM

thanx, Ben

 

[DaveCombs]

Originally posted by Fore Check
How 'bout a pic of that nosecone? I'm assuming Sandman made it....

None other than! Covered in West Systems epoxy and taking just a couple more days to completely cure. With a name like Sandman, it's gotta be good!!!

And how big is it?

No RockSim; I'm sure it will create a little drag. Sandman also added a little scallop in the ramjet, so it's actually not flat like the original. Little details like that make it that much more special.

 

[DaveCombs]

Shock cord is 25' of 1/2" tubular nylon from a local outfitter store (GS Outfitters for you locals). The knot is a Scout's best friend, the bowline, and it's set with epoxy.

 

[ben]

weird. I thiunk you have the same kitchen table as me Looking good

thanx, Ben

 

[DaveCombs]

Motor mount installed, glued using a healthy dose of Titebond II. I went back and added a little more to that thin spot by the U-bolt.

 

[DaveCombs]

Taken directly from DanB's drawing, transferred to 1/10" quad engineering paper.

 

[DaveCombs]

Pattern traced 4 times onto Midwest 1/8" 5-ply birch. Leading edges follow the grain. I'm going to try my hand at cutting them out using my Dremel with a "Roto-Zip"-style bit later this week, and then sand them straight with a bench-mounted belt sander (if I can find one) or a sanding block. Or, I might do the clamp & sand thing to get them all shaped consistently. I'll do some leading and trailing edge rounding using a small palm sander. Finally I'll seal them with SIG sanding sealer.

 

[DaveCombs]

A test fit of the airframe, payload section and that gorgeous nosecone; a yardstick is propped up against the front. It stands 56 1/2" tall right now, and it will pick up another inch or so from the trailing edge tabs on the fins.

 

[Fishhead]

NICE!! What's the timetable on this project? Any idea when the first flight will be? I love the idea of the upscaled Estes kit for a cert.

 

[DaveCombs]

Question and Answer time!

Ben: Thank you! Yes, I can't count the number of times I've seen a kitchen table like mine in pictures posted on TRF.

Fore Check: I'll hit up Bruce; I can take some good measurements of the cone for RockSim.

Fishhead: It will almost certainly be at a QUARK launch at VOA Park in Cincy; I'm looking toward some time in March, once the weather breaks. I hope you're there! I'm also considering bringing it to NSL 2007 since it's just next door in Muncie.

 

[DAllen]

That nose cone is a work of art. Nice overall design by the way. That should be a beauty when it's done.

 

[loopy]

Woo hoo! I was wondering when you were gonna get off your duff and post this! It looks awesome! I can't wait to see the fins!

 

[DaveCombs]

I'll bring them into work (unless the guards stop me ).

Gotta start saving up for the 38mm motor...

 

[Fishhead]

Originally posted by DaveCombs
I'll bring them into work (unless the guards stop me ).

Gotta start saving up for the 38mm motor...

How do your guards go about stopping you? I guess ours do it by changing the tone of the snoring. I can't tell you how many times I've had to wake them up. I mean, I know it's night shift, but I've managed to stay awake for 21+ years now.

 

[loopy]

Originally posted by Fishhead
How do your guards go about stopping you? I guess ours do it by changing the tone of the snoring. I can't tell you how many times I've had to wake them up. I mean, I know it's night shift, but I've managed to stay awake for 21+ years now.

Wow - the longest I've ever stayed awake is like two and a half days! 21+ years??? That's amazing!

Dave - I don't think they'll stop you with fins...lol After all, they didn't even come and get me when I carried in my Expediter, Small Endeavour, and AMRAAM...lol Man, I can't wait to see this thing, though! Awesome job!

 

[DaveCombs]

I rough cut the fins using the spiral bit for my Dremel. Results were, well, mixed. It's effective, but you can't really cut anything too straight because of the way the bit bites into the wood and makes you want to follow where it's tracking (rather than the other way around). There is also a very small amount of "fuzzing" on the bottom surface of the wood, but it wasn't all that bad, certainly nothing that a little sanding won't take care of.

I tried to be relatively patient and slow with it, but all I really managed to do was cut where I wanted to and not cut into the fins themselves. I left at least 1/4" or more between any two traced line, and I'm glad I did. Now would be the perfect time for a scroll saw...

I give it a 2 out of 5.

 

[loopy]

Interesting. So, what's the plan to clean them up?

 

[ultrasonicTim]

Very Cool! I sure hope I get to see this one take off. Great job so far!

Tim

 

[Bohica]

Looking good Dave!

On the fin issue...Clamp and sand baby!

I picked up a bench top belt sander from Sears not too long ago for $60. Worth every penny!

A good drill press, belt sander, scroll saw, and small lathe are worth their weight in gold for anyone going beyond kit building. I did without these essential tools for far too long!

 

[DaveCombs]

Thanks, guys. I'd be interested in getting the bench-top sander myself if I had a place to put it. Since two of my boys are living in my garage (I have a 1-car, and we turned it into their bedroom), I'm a little workshop-challenged. But, I'll see what I can do. I happened to be at Lowe's last night, and I was looking at scroll saws. There were 2 under $100, so I'm tossing that around in my head as well. The drill press would be a great investment too; I've gone over to my ex-father-in-law's place to use his big 1/2" press for things, and every time I go home thinking, "I gotta get one of those!" Snag a fly cutter and I'd be in the centering ring business...

Tim: Stay tuned; I'll post when I'm going to send her up at VOA.

 

[Sailorbill]

Originally posted by DaveCombs
I rough cut the fins using the spiral bit for my Dremel. Results were, well, mixed. It's effective, but you can't really cut anything too straight because of the way the bit bites into the wood and makes you want to follow where it's tracking (rather than the other way around). There is also a very small amount of "fuzzing" on the bottom surface of the wood, but it wasn't all that bad, certainly nothing that a little sanding won't take care of.

I tried to be relatively patient and slow with it, but all I really managed to do was cut where I wanted to and not cut into the fins themselves. I left at least 1/4" or more between any two traced line, and I'm glad I did. Now would be the perfect time for a scroll saw...

I give it a 2 out of 5.

If you want straight lines try this.

1. Figure the distance from the outside of the guard to the outside of the bit.

2. Clamp a section of aluminum angle that distance to the inside of your cut parallel to the cut line.

3. hold your rotozip tool tight to the side of the angle and move it along the angle.

This will give you a nice straight line with minimal wavyness.

I have been looking at the belt/Disc combination sanders at Menards etc. I really think this will be my next big tool purchase.

I have access to many power tools at work but we are not really supposed to use them for our own projects.

 

[Fore Check]

Hey SailorBill:

I recently purchased THIS SANDER and I'm very, very pleased!

I purchased it to go with my new band saw, and today I took delivery on my new bench router. "Close Cut" on the band saw, finish the shape on the sander, then bevel on the router.

 

[DaveCombs]

SailorBill: Understood about the "fence" idea. But again, I'm a little workshop-challenged.

I went to Harbor Freight today and looked at - but didn't buy - a 4" disc sander. It was $30, which is reasonable, I suppose, but it's so small that it may not be very useable for anything else. It had a little sewing machine motor.