Engine shot through rocket?

Hey im new here and have been into rockets for a couple of years. I recently bought the estes Leviathan and have been building it. The only thing Im seeing wrong is that theres no thrust ring.. Like the tube that holds the motor is just straight through.. So wont the engine shoot through my rocket??

Thanks for you help. I can post pictures in a couple of hours if you guys would like.

The larger motors have a flared base that acts as a rearward thrust ring. This allows for motors of any length to be used.

Yes, Make a thrust ring on the motor with masking tape equal to the thickness of the motor tube wall. This will keep it from pushing through.

Also use some to get a tight fit so the ejection pops the chute instead of kicking out the motor (call a friction fit).

Welcome!

The thrust ring is part of the motor. It is the end opposite of the yellow cap.



Greg

No need for a thrust ring at the forward portion of tube or making one out of masking tape on your motor. As mdoering said the single use F and G motors have the "thrust ring" built in on aft portion of the motor. The reload casings similarly have a flared part in the aft of the case to prevent this as well.

When I got back into this hobby last year that was one of the very first things I noticed on the bigger rockets and asked the same thing.

Also ... some kits like Quest Big Dog which take the 29mm motors come with a thrust ring which the instructions say to glue into the forward part of the motor tube. I learned the hard way that this is really not necessary and severely limits your motor choices if you want to use reloads. As mine is built with the thrust ring I can only use single use motors or a 29/60 reload. Not able to use the 29/40-120 which would have been ideal. Oh well live and learn.

Figured this took Estes motors. Your reload cases and the newer molded single use motors have a thrust ring built in.

cavecentral said:

Figured this took Estes motors.

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The Estes Pro Series motors are relabeled AeroTech units so they have the same plastic "rear closure" as the SU AeroTech and reloadable stuff...

cavecentral said:

Yes, Make a thrust ring on the motor with masking tape equal to the thickness of the motor tube wall. This will keep it from pushing through.

Also use some to get a tight fit so the ejection pops the chute instead of kicking out the motor (call a friction fit).

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Friction fit is not necessary with the nifty new Estes motor retainer, which comes with all the new Pro Series II kits. You can also buy it separately at Hobbylinc.
I've upgraded all my 29mm rockets to this, best inexpensive motor retention available.

I have trouble calling them Estes motors . I meant the black powder ones.

Nice that it comes with motor retention. Most kits do not. Useful to understand the concept of a friction fit, but yes not necessary since it has retention. Answering question from a general point of view, not being familiar with this kit.

Thanks everyone for your replys.

Ok im not worries then! So wheres a good place to buy reloads? Ive looked around but google doesnt even recognize it..

I buy all my 24mm reloads from Hobbylinc here: https://www.hobbylinc.com/Model_Rockets, and I know several other people on here also get their 29mm reloads from there. Hobbylinc has great prices on other stuff, too.
Welcome to TRF!

Oh cool! thanks!

BTW, has anyone used party streamers for recovery padding? it was a buck and its flame resistant. Worked like a charm for my LPRs

SkyDiv3r17 said:

Oh cool! thanks!

BTW, has anyone used party streamers for recovery padding? it was a buck and its flame resistant. Worked like a charm for my LPRs

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I know they have been used as streamers, so not sure about that the other though.

Most folks use cellulose insulation (a.k.a., "dog barf") as their "anti-toast" buffer between the ejection heat and the recovery gear. It is available at your large, home centers (Home Depot, Lowe's, Menard's, etc.) in bales. It works well and is environmentally friendly, in that it breaks down fairly easily.

Greg

I would recommend the Rouse-Tech authorized version of the AT 29/40-120 case. Commonwealth Rocketry has had the best price on this case recently at $35 but they are currently out of stock.

Wayco said:

...
I've upgraded all my 29mm rockets to this, best inexpensive motor retention available.

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Thought the "best inexpensive motor retention for 29mm was the top from a 32oz gatorade bottle... (Haven't tried it, but hear it works well!) :wink:

I would either consider dog barf or go with a nomex blanket/nomex wadding for MPR and some LPR...

Welcome to the forum!!

SkyDiv3r17 said:

BTW, has anyone used party streamers for recovery padding? it was a buck and its flame resistant. Worked like a charm for my LPRs

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Yup, I use them almost all the time. Everything from LPR and up to 3-4" diameter MPR. I wad some up and stick it in the motor tube from the top, but have also shoved it in from the bottom. I pushed it just ahead of the motor and works great. (Not too tight though, but you already knew that.) I also fold it up a few longer pieces of it, and lay it over the top end of the motor tube, in my larger diameter rockets.

Sometimes I leave the folded streamers on top really long (5-6 feet) and tape pennies, nuts, washers, etc. to them. Makes for good 'tracking' and the kids love to chase em down!


Welcome to the Forum! And yes, pictures and/or videos are always welcome!

emckee said:

Thought the "best inexpensive motor retention for 29mm was the top from a 32oz gatorade bottle... (Haven't tried it, but hear it works well!) :wink:

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They work great. All my 24mm rockets use the 12oz Gatorade bottles as retainers and they work perfect.

The great thing is if I add a thrust ring 2.75 inches up the tube, I can fly with 24mm reloads or remove the screw on cap and friction fit black powder Ds as well.

emckee said:

Thought the "best inexpensive motor retention for 29mm was the top from a 32oz gatorade bottle... (Haven't tried it, but hear it works well!) :wink:

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Not sure what a 32 oz. bottle of gatorade costs, but $5.99 for two retainers at Hobbylinc might be cheaper. And you don't have to deal with the toxic chemicals in the bottle either. Win win situation. Sure, you can argue shipping costs and probably dumpster dive for an empty bottle, but I prefer to order a good product from a good company and have it fit right out of the bag. No muss no fuss, just install it and fly the rocket.My intent was to remind others that Estes includes these handy retainers with all their Pro Series kits. I got three packs for free on a warranty deal when an Estes composite motor melted my Vagabond, can't beat that deal!

McKailas Dad said:

Yup, I use them almost all the time. Everything from LPR and up to 3-4" diameter MPR. I wad some up and stick it in the motor tube from the top, but have also shoved it in from the bottom. I pushed it just ahead of the motor and works great. (Not too tight though, but you already knew that.) I also fold it up a few longer pieces of it, and lay it over the top end of the motor tube, in my larger diameter rockets.

Sometimes I leave the folded streamers on top really long (5-6 feet) and tape pennies, nuts, washers, etc. to them. Makes for good 'tracking' and the kids love to chase em down!


Welcome to the Forum! And yes, pictures and/or videos are always welcome!

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Oh cool so its not just me . Yeah streamers seem to be the way to go! So much cheaper and easier than everything else.. Ill get some pictures of my rockets and stuff later today. Im in school right now haha.

So does anyone have any recomendations for the biggest reloads that will go in a leviathan? I want to shoot it as high itll go, but want it to be as cheap as possible (reloads).
-Broke college student. lol

Wayco said:

My wife Sharon built her Leviathan with a cold air baffle that puts a bulkhead at the top of the coupler. I just measured the MMT and there is plenty of room for a CTI five grain casing. If you didn't baffle it, I'm sure you could put a 6XL casing in it. With a five grain, the Classic reload H140 would put ours up to 2400 ft.

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I honestly have no idea what you just said . cold air baffle? bulkhead? coupler? MMT? CTI? Thanks so much!

SkyDiv3r17 said:

I honestly have no idea what you just said . cold air baffle? bulkhead? coupler? MMT? CTI? Thanks so much!

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Sorry, didn't realize you were new here. Let my try again.
Sharon built her Leviathan with a motor mount tube (MMT) that went from the bottom of the rocket (where the motor retainer is) up to the coupler that joins the two body tubes together. The coupler fits inside the upper and lower body tubes. At the top of the coupler she added a bulkhead. Here is a pic of the top of the coupler:


The four tubes sticking through the bulkhead are about three inches long and that's where the ejection gasses come out. The eyelet is an anchor point for the recovery cord. The bottom of the coupler has a hole that the motor mount tube fits through:

So the ejection charge flows up the motor mount tube and hits the back of the bulkhead, then it has to backtrack down the coupler and reverse directions again to come out the four tubes you see at the top. That cools down the gas and hopefully doesn't melt the nice nylon chute that is supplied with the kit. This design is called a "cold air baffle". Here is a shot of the MMT at the top of the fin can:

The coupler/baffle slides down over the motor mount tube leaving a gap between the top of the MMT and the bulkhead, then you slide the upper body tube onto that. Here is a shot of the coupler/baffle inserted into the lower body tube/fincan:

For a rocket this large, you have to use a composite propellant motor. Estes has several single use motors designed for the new Pro Series II rockets, but I like to use CTI (Cesaroni Technology Incorporated) reloads. They have a great selection of reloads for the 29mm MMT that Estes supplies with this kit. If you built this rocket stock and used the supplied MMT without a baffle, even the largest 29mm motor could be inserted into this rocket. What would happen when you flew it is up to the rocket gods.....
Hope this helps.
In closing, here is a picture of Sharon and her Leviathan:

Woah thats just awesome!! I wouldnt have even thought about something like that. So you bought a seperate MMT, is it just taller or taller and wider? And what about the added weight? I think you said your using h engines so it doesnt matter? What can I do with the stock MMT to launch it higher?

I really appreciate the help! Reading your post was like watching an intense movie while eating the perfect bowl of popcorn op:

Until you get your Level 1 Certification you won't be able to buy an H motor - that being said the Leviathan can be used for Lev.1 cert. launch once you have all your paperwork filled out and witnesses lined up. But this kit will go quite well on just about any G motor you care to put in it. I have AeroTech 29/40-120 cases and up to G70 motors for mine. Had a lot of fun building this kit - was surprised when I noticed that the kit didn't include decals - so I made my own. Didn't want it looking like everybody elses.

This is what our forum is all about, sharing ideas common to our hobby. The cold air baffle I learned from another member here who is also a member of our local club, the SSS. A lot of what you saw there I have picked up in the last year or so by asking the same questions that must be flying around in your head right now.
As for the MMT that I used, got it from Balsa Machining (https://www.balsamachining.com/) and it comes in 34 inch lengths and is foil lined on the inside, (T52-HMF on their website) so yes it's thicker and heavier than the one supplied in the Estes kit. Sharon's rocket weighs 22 oz. which is a bit heavier than the stock kit built with white glue. That's why Sharon will probably fly it on a CTI "G" reload for it's first flight. There are several "F" motors that would work, but we like to get at least 1000 ft. when flying the bigger rockets. I have an Aerotech 29/40-120 hobbyline casing that has several good reloads that would work in this rocket, but that's MY casing, and Sharon doesn't like Aerotech reloads because they are harder to build than CTI.

SkyDiv3r17 said:

What can I do with the stock MMT to launch it higher?

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Leave it stock. If you don't put a baffle or internal thrust ring in it, you can use reloadable motor casings with motors up to a "G". Realistically though, the Leviathan isn't a "high altitude" rocket. 3 inch diameter rockets with four fins have too much drag. Even using high power "H" and "I" motors you can only get a couple of thousand feet with it. Anyway, Sharon's rocket with the baffle could still fly a motor much larger than anything we have a 29mm casing for....

Oh ok! Idk about certification so ill stick to g motors. Wayco I appreciate all the explanations. Ill just have to find some kind of reload system and stick with that. Thank you!

Wayco said:

Not sure what a 32 oz. bottle of gatorade costs, but $5.99 for two retainers at Hobbylinc might be cheaper. And you don't have to deal with the toxic chemicals in the bottle either. Win win situation.

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A 32 oz. bottle of Gatorade costs $.88 at the local grocery store. Toxic Chemicals???? I hope not. I usually drink 2 of those bottles every launch day.

BobH48 said:

A 32 oz. bottle of Gatorade costs $.88 at the local grocery store. Toxic Chemicals???? I hope not. I usually drink 2 of those bottles every launch day.

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https://www.oneresult.com/articles/nutrition/gatorade’s-mystery-ingredients

How you doing with soda's? A lot of my rocket buddies are overweight and don't know about high fructose corn syrup either.... But let's not let this get off topic, the OP just wants to make his Leviathan go higher and we all know that loosing weight and adding power will do that.

Wayco said:

https://www.oneresult.com/articles/nutrition/gatorade’s-mystery-ingredients

How you doing with soda's? A lot of my rocket buddies are overweight and don't know about high fructose corn syrup either.... But let's not let this get off topic, the OP just wants to make his Leviathan go higher and we all know that loosing weight and adding power will do that.

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I drink the G2 which is the sugar free Gatorade. I only drink it at launches. I was finding myself wiped out when I got home and it seems like the electrolytes seem to help me get through the day. I only drink soda rarely. Usually a few of us go out to eat after a launch and I'll get soda then. Other than that. I don't drink it.