3 estes bt-80 tubes on a 24mm tri cluster

[dippind27]

I am creating a rocket using estes bt-80 tubes. 3 of them to be exact. I have a 24mm tri cluster engine mount. From my research im probably going to test it first on D12-3's but if anyone knows something better let me know. I dont have a computer so i can not run programs like rocksim. My main question is will the blast from the 3 D's be enough to travel up 3 feet of rocket and pop the nose cone for recovery? Having a cluster engine sort of eliminates the possibility of a stuffer tube. Another possibility i thought of would be to glue the nose cone into the top tube and have the rocket seperate between that and the bottom two tubes? Pretty much extending my nose cone 14" with the tube lol this is my first bigger rocket so any suggestions would be awesome!! Thank you

 

[Nytrunner]

3 feet of BT-80 is a lot of volume, but 3 D12s should give a lot of Pop as long as they all vent into the airframe.

Don't give up on a stuffer tube though, If you take a 29mm tube (or even a 24mm tube), Put BT-80 centering tings on each end and mount it a couple inches ahead of your motor tube, You'll cut down a fair amount of volume. It'll also provide a shock cord mounting point much further away from the hot gas of the ejection charges.

Your other idea is good too, but instead of just glueing the nose in and breaking the airframe lower, You'll want to out a bulkhead on one end of the coupler. That will seal off the forward section and the ejection gas won't have to pressurize that section.

Good luck! (take pictures)

 

[EXPjawa]

Alternatively, you can have three parallel stuffer tubes. That's what I've done before.

 

[cavecentral]

Loc viper 3 and 4 work fine with d12s. Viper 4 using 4 d12-7s and motor ejection many times.

 

[dippind27]

My question for a stuffer tube is wouldnt putting it a couple inches up from the motor mount create a small chamber before the tube and prevent the full power of the blast from going up? I feel like 3 tubes attached right to the mount would be more effective right?

 

[EXPjawa]

If the three tubes open into the full body tube, then neck down to a smaller stuffer tube, it'll have a partial baffle effect. It also means that you'll loose some pressure. Maybe that would be mitigated some if there was a sort of funnel to collect it going forward. Personally, as I said before, I'd just extend each motor tube forward so that there are three stuffers in parallel. Then if any one of them fires first, it has the same function as if it was single-motored. Keep in mind that you will not have all three charges firing simultaneously, so you have to assume that your deployment will occur with only one motor.

 

[Daddyisabar]

Use D12-5 or D12-7's, unless it turns out to be a very heavy or draggy rocket. 3 D12's is like and E 36, plenty of speed needing a longer delay. Use good igniters, not Estes Starters.

 

[dippind27]

I assumed D12-3's would be best because i heard D's have more initial thrust so the rocket would be flying lower and slower. I have no idea the exact weight of it yet but i dont have any certification so i wont be going over a pound. I have no idea how high this would generally fly. I also only guessed the 3 second timer because ive built a rocket that recommended c6-3 and i used a c6-5 just because i had some and it ended up making a huge difference in recovery i was amazed. On the c6-5 it deployed with only 100 feet or so left to go but with the 3 second timer it deployed beautifully. It was also slightly windy the day i used the c6-5 so that could have played a role as well

 

[Tinker]

Use D12-5 or D12-7's, unless it turns out to be a very heavy or draggy rocket. 3 D12's is like and E 36, plenty of speed needing a longer delay. Use good igniters, not Estes Starters.

What are good igniters for clusters now that the Quest ones seem to be gone for the time being?

Tinker

 

[Daddyisabar]

What are good igniters for clusters now that the Quest ones seem to be gone for the time being?

Tinker

Good question. Use any of the old black tipped Estes or go to rocketflite.com . See if you can source some Q2G2's or make your own.

 

[Daddyisabar]

I assumed D12-3's would be best because i heard D's have more initial thrust so the rocket would be flying lower and slower. I have no idea the exact weight of it yet but i dont have any certification so i wont be going over a pound. I have no idea how high this would generally fly. I also only guessed the 3 second timer because ive built a rocket that recommended c6-3 and i used a c6-5 just because i had some and it ended up making a huge difference in recovery i was amazed. On the c6-5 it deployed with only 100 feet or so left to go but with the 3 second timer it deployed beautifully. It was also slightly windy the day i used the c6-5 so that could have played a role as well

I would launch your 3 motor cluster in little to no wind with a long rod or rail. With the mighty D12 you will be going lower but faster, hence the lengthened delay time to say 5.

 

[dippind27]

Whats wrong with the estes ones? Just bad for cluster?

 

[dippind27]

Is it complicated to make your own?

 

[dhbarr]

Whats wrong with the estes ones? Just bad for cluster?

Since they took the pyrogen out of the mix, they don't light off as quickly as they used to.

In a cluster, this can lead to one or more motors not lighting as they are pulled off the igniter before they get going.

 

[dippind27]

After searching for hours it seems q2G2's are sold out everywhere. All i can find are estes sonic ignitors and first fire's. I could use first fire's but i would have to invest in a new launch controller.

 

[dhbarr]

After searching for hours it seems q2G2's are sold out everywhere. All i can find are estes sonic ignitors and first fire's. I could use first fire's but i would have to invest in a new launch controller.

Just get a set of Gator clips and a nice 12v battery, will be worth it no matter what you're lighting off.

 

[dippind27]

Do i even need to get all fancy with it and build like an ignition switch and all that? Or can i just gator clip both ends of like 20 feet of cable and when im ready to launch just hook the clips right to the battery?

 

[dhbarr]

Do i even need to get all fancy with it and build like an ignition switch and all that? Or can i just gator clip both ends of like 20 feet of cable and when im ready to launch just hook the clips right to the battery?

That would be in violation of the Model Rocketry Safety Code.

 

[dippind27]

Good to know. Thank you you've all been alot of help! It will not let me upload photos from my phone so i will eventually upload some to a computer so i can show you guys my creation. I think its rightfully deserved name should be Big Boss Bertha

 

[dippind27]

These are last weeks photos. Since then ive built the stuffer tube. the Motor mount and stuffer tube have been installed. I did 3 parallel stuffers 10" long attached right to the mount. This left the perfect amount of room for a tube coupler. Ive attached that tube to the one that will house the recovery system. I am in the process of filling the tube seems with wood filler and prepping to paint!

 

[neil_w]

It will not let me upload photos from my phone

Use the Rocketry Forum app to upload pictures, or Tapatalk. IMHO the apps are *much* better for using on a phone anyway.

 

[dippind27]

Just realized that there was an app today. Thats what i used to upload them. Thank you though!

 

[dippind27]

Didnt realize what i was getting into cost wise for this rocket. Costs 65 bucks to order engines and starters just to launch this twice. And im already 200 deep in materials for the rocket. A big step up from 20 dollar kits and 10 dollars to launch it 3 times!

 

[Nytrunner]

I forgot how much space there is in a BT-80. Those 10" motor tube extensions sure cut down a lot of your useless volume.

What kind of engines did you buy? Did you order them and have to pay hazmat or something?

 

[Micromeister]

Been flying D12 clustered BT-80 models for decades. I've found it is best to build the Cluster motor mount onto a mixing chamber. This chamber is nothing more then a BT-80 coupler lined with Stainless steel screen, 1/8" plywood bulkheads and epoxied to the BT-60 Upper stuffer tube.
One more thing 4- D12's fit very nicely in a BT-80 in standard BT-50(24mm) motor tubes.

This arrangement has worked perfectly on a number of Up-Scale Models, Ram-Jet, Ultra Orbital Transport, 3X Laser-X, Aerobee-Hi Test, 5-D12 Clustered Brighthawk (3D cluster core & 2- boosters) 3X Bomarc.

Contrary to DaddyisaBar D12-5 or 7 suggestion: D12-3's are usually the motor of choice because of the increased Frontal Area, Mass & Drag of these rockets. 3 Seconds genearlly has them deploy right at apogee. I have used D12-5's in a 4-D12 cluster augmented Optima (Single D12-5 Core and 3 strap-on D12-5's).

 

[dippind27]

Got them from ASP. They seem to be a pretty good site for making your own rockets from scratch. Only place that sold the ignitors i needed as well and had a fairly cheap price on the D12's. Also didnt want to pay 2 seperate shipping fees buying the engines elsewhere. As far as i know i did not get charged a hazmat fee. Most other sites did mention having a fee though. i did alot of searching trying to find the best deal and ended up with this. Hopefully theres not a cheaper option i missed out on. Probably should of asked around first

 

[Daddyisabar]

Didnt realize what i was getting into cost wise for this rocket. Costs 65 bucks to order engines and starters just to launch this twice. And im already 200 deep in materials for the rocket. A big step up from 20 dollar kits and 10 dollars to launch it 3 times!

If you have a Hobby Lobby near use the 40% off coupon, no shipping on D12-5's. It is worth it for the thrill of clustering and with clusters you can fly anything depending on configuration. Much more satisfying than using one, powerful composite motor. More difficult - yes. More expensive for parts, motors and launch equipment - yes. Greater chance of CATO or many other potential disasters - yes. Improved performance over composites - no. Wait, the cluster guys must be crazy!

 

[Micromeister]

Got them from ASP. They seem to be a pretty good site for making your own rockets from scratch. Only place that sold the ignitors i needed as well and had a fairly cheap price on the D12's. Also didnt want to pay 2 seperate shipping fees buying the engines elsewhere. As far as i know i did not get charged a hazmat fee. Most other sites did mention having a fee though. i did alot of searching trying to find the best deal and ended up with this. Hopefully theres not a cheaper option i missed out on. Probably should of asked around first

Wow!
D12's are getting expensive, but you'll do a lot better by buying them in bulk (along with other motors and/or kits) From Belleville Wholesale Hobby www.bellevillehobby.com Depending on your order size you can get up to 40% discount and very reasonable shipping.

 

[Daddyisabar]

Hey Micromeister, please re read my post of the 25th! I have not seen his built rocket but it doesn't look like he is building a heavy drag queen like a BOMARC that would automatically need D12-3's. Looks like a single BT 80 Nose cone on a three 24mm mount. I also launch at a mile high or higher in dry conditions. If he is launching down at Sea Level in high humidity D12 3's could work. What is the worst that could happen? A little early or late on the ejection is usually no problem. Use a nice long shock cord and there are many additional anti-zippering techniques if one desires to use them.

 

[dippind27]

Yeah i was gonna but they had like 20 dollar shipping. im still semi new to rocketry and am on a low budget so cant exactly buy bulk at the time. Im a spawn of rocketry being taught in school. Built my first rocket with my fifth grade teacher. Was into it for a year or so then phased because i was still a kid. I found my old rockets laying around a couple months ago and it reignited my passion for rocketry. Im trying to upgrade one step at a time so ill keep that in mind for the future!