Calling all Estes Leviathan builders. Let's talk mods.

It flies great on the CTI 3 gr H90. I used the stock shock cord mount and elastic plus another 10 feet of para cord. a friend of mine BEC added some nose weight but mine flies fine without it. If you want a baffle go right ahead. They work well.

Since this is coming up soon in my build queue i too would like to know about any possible mods thanks for posting this

A kevlar shock cord anchor would be nice. Attach it to the shock cord with a barrel swivel, to reduce twisting.

Also, attach the parachute to the cone with a nice heavy snap swivel.

If you think you might use larger than suggested motors, a little nose weight might help.

Rail buttons?

Semroc doesn't make a baffle, but it looks like Balsa Machining Service has a 3" bulkhead disk. If you get two of these, and two 4" pieces of (say) heavy duty 24mm motor mount, you can make a baffle. You'll need to bore a hole to fit a tube end in each disk, offset from center. You can see a picture and assembly details for this sort of baffle in the instructions for many Semroc kits, such as the SLS Hustler. The PDF is on the Semroc site.

Here is my .ork file for my Leviathan as built.

Mods were few. I got a tube coupler and two ply disks from BMS and converted the upper few inches of the body into a payload section. I like to fly altimeters. I actually used half of the BMS coupler as the body joint and the kit-supplied coupler for the base of the payload section as the BMS coupler for 3 inch tubing was a bit tight. I used about as small an eye-bolt as I could find at Lowe's through the two ply disks for a shock cord/'chute attach to the payload section. This was the only "high power-ish" construction.

There is also one ply ring with a chunk of BT-50 in it in the payload section to keep the altimeter from rattling around inside that huge volume.

For a baffle I had BMS custom cut two ply rings so I could make a baffle in the style of the two-tube baffles sold by Semroc for some of the larger body diameters (sorry, no picture on their site - I just looked). One square of Estes wadding in the upward-facing tube is all that I use. In five flights there has been no damage to the 'chute.

During construction I left off the aft centering ring until the fins were installed and filleted to both the motor tube and the inside of the airframe tube. I used plain ol' Elmer's Glue-All for all of this gluing. External fillets were done with Titebond trim and moulding glue.

As Derek noted, I put a bit of nose weight - about an ounce - in the tip of the nose cone in order to get over 1.4 calibers of stability with a CTI 3-grain 29mm motor aboard. That, and attaching the motor retainer to the motor mount tube were the only places I used epoxy. Everywhere else was Elmers or Titebond. I used the trifold mount and the kit shock cord as directed. I did get a big fishing swivel to use to attach the kit's 'chute to the eyebolt in the base of the payload section.

All up weight is just under 22 ounces plus altimeter (0.3 ounce - PerfectFlite Pnut) and motor.

View attachment Leviathan_share.ork

Kevlar cord tied around the motor mount just below the forward centering ring, I then cut the Kevlar about 4 inches short of the end of the body tube and tied the shock cord to that.

Another mod I made was cut the fins flush back of the rocket, removing all the sweep in the trailing edge. This was mostly because I splintered the end of a fin when landing in the parking lot on a G64W. The splintering damage was pretty bad so I made the mod on Open Rocket and the CG and CP didn't change too dramatically, and in simmed flights the rocket actually gained anywhere from 50-100 feet. I tested the mod last week and it still had the straight as an arrow flight characteristics that the Leviathan has shown.

Now it looks more like a Patriot missile. I'll post a pic of the mod shortly

1010 are most common with small and mid sized rockets. Then when you get to flying bigger and heavier rockets you go with 1515 or uni-strut. Check with your club and see what they fly and im sure they will not have a problem you using their setups. I will suggest using GLR rail guides, they are great quality and super easy to install and align.

Use the coupler to build your baffle in, make you top of your baffle out of 1/4 ply put an eye bolt through it and hang your laundry from a 12 foot kevlar shock cord attached to the eye bolt. That's the only mods that a Leviathan needs. My Open rocket file has it stable with any standard six grain motor, so no nose weight needed. You just wont have enough room to put a 6 grain motor in it if you use the coupler for the baffle. If I would have been thinking of that big of a motor when I built it, i'm sure I could have done it. Its only like a half inch to small.



TA

Green Jello said:

Many people have suggested that this can be a great model to do a L1 cert flight on. So if I were to do that, what mods have you guys done?

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I don't have a Leviathan but I do have a Ventris which is similar. It is also my first MPR model. I built mine with a baffle in the coupler as I do with all my smaller rockets, this one's just beefier. I used the tri-fold method for the shock cord as I have gone back to doing on LPR models, but I beefed it up using cardstock instead. With that, the rocket survived a VERY late deployment near the ground at velocity upwards of 200mph with hardly a scuff mark to show for it.

What I regret about building mine is not building it for dual deployment from the get-go. Now I have to retrofit it. I have a G motor for it and I would like to see it again afterword.

Fins are a bit draggy. Different fins would be in order.

So far I have built and flown two Leviathans and, will probably be doing a third. I built the first one stock. The second I had an extra 30" length of 3" BT and a coupler laying around so, I made an Leviathan XL. I flew them both last weekend. The LXL flew great on a g80-7.

Green Jello said:

Ok....my rail buttons just arrived. I am a first timer with these things and I decided to use them after completing the main construction of the Leviathan.

View attachment 99115

So my questions are:

1. What is the best way to install these things? I think I heard you use the machine screws and some epoxy in the hole.

2. Where would you put them on the body tube?

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Usually they get screwed into wooden blocks attached to the centering rings, or screwed into the body tube with t-nuts in the back...
I'm not sure how you would proceed using either of these methods with what I see there. If I were you, I would secure them with drywall mollys. I have never done this, however, but I know it has been done.

Next time you build something that's going to have rail buttons, attach blocks of wood to your CR's and mark where the blocks will be when everything is assembled.

awseiger said:

Next time you build something that's going to have rail buttons, attach blocks of wood to your CR's and mark where the blocks will be when everything is assembled.

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What he said. But in your case, since the rocket is already assembled, a lot of people use well nuts.

qquake2k said:

Since it's not a very heavy rocket, another thing you can try (that I've done a couple of times) is to drill a hole smaller that the screw in the body tube. Then put epoxy inside the hole with the pointed end of a small bamboo skewer (or some such), screw in the rail button, and lay the rocket on its side with the rail button down, so the epoxy will pool around the screw. If you ever start using more rail buttons, Dog House Rocketry is a good source.

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I think this is most likely the way I will go. Do you use the wood screws or machine screws to do this?

Green Jello said:

I think this is most likely the way I will go. Do you use the wood screws or machine screws to do this?

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I'd use wood screws, since the threads are more coarse. Give the epoxy more to grab onto.

qquake2k said:

I'd use wood screws, since the threads are more coarse. Give the epoxy more to grab onto.

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Any opinions on where to put the two buttons on the body tube? I'm worried about the upper one snagging the chute and stuff with the pointed end of the screw in there.

Green Jello said:

Any opinions on where to put the two buttons on the body tube? I'm worried about the upper one snagging the chute and stuff with the pointed end of the screw in there.

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I'd put it just below the upper centering ring. If you did want to put it in the body tube where the chute goes, you could use a short screw and an acorn nut.

qquake2k said:

I'd put it just below the upper centering ring. If you did want to put it in the body tube where the chute goes, you could use a short screw and an acorn nut.

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Are you saying one at the bottom of the rocket and the upper one at the top of the motor mount? Is that enough separation?

Green Jello said:

Are you saying one at the bottom of the rocket and the upper one at the top of the motor mount? Is that enough separation?

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How far apart are the centering rings?

qquake2k said:

How far apart are the centering rings?

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Here is the layout from Open Rocket:

Green Jello said:

Here is the layout from Open Rocket:

View attachment 99345

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In my opinion, they'd be far enough apart.

qquake2k said:

In my opinion, they'd be far enough apart.

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Putting one at the bottom and the other at the CP so it can go through the tube coupler?

Green Jello said:

Putting one at the bottom and the other at the CP so it can go through the tube coupler?

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No, I meant one at the bottom and one just below the forward centering ring.