CTI Mellow's in a cluster?

[HHaase]

Looking at some longburn clusters for my 4-29SS when warmer weather returns. How well does a CTI Mellow light in a situation like that? Considering the 3-grain 29mm G33's and the 4 grain H42's.

-Hans

 

[djs]

I've seen G33's do strange things when lighting (taking a while to light, lighting, stopping, and restarting). Might be a bit of a gamble, unless you're doing 2 main normal motors and then airstarting 2 mellows?

 

[djs]

Another option might be the G54 3 grain red. I haven't had any issues with that one- it's a nice longer burn. Assuming, of course, you can find one

 

[HHaase]

Yeah, the G54's would be nice as well. Same with the H54 for just a hair longer burn and a bit more total impulse.
And I am planning on being able to air-start a pair too ..... when I get brave enough.

All part of the fun when planning to fly a new rocket. Oh the possibilities on this one.

 

[Rocketjunkie]

I've flown my 4-29SS on 2 H53's. I didn't think 2 G33s had enough thrust. The Mellows have BP pellets and are lit with ematches. They cluster well. My 4-29SS is dual deploy and weighs about 3 lb. without motors. 4 G33s would work well as I've flown mine on 4 Estes F15s.

 

[CoyoteNumber2]

I've flown mine on 4 Estes F15s.

That sounds cool. Have a photo?

 

[Rocketjunkie]

That sounds cool. Have a photo?

Got video
[YOUTUBE]uY-HDVoiZSg[/YOUTUBE]

 

[jrkennedy2]

I used 4 of the single use AT G-74-9w. 3 good flights until I didn't check the voltage on a launch battery. Then only 1 lit. It flew straight up to about 100'. Then came back in on a tail-slide and broke its back. What I learned, always check battery voltage on a cluster start. I also run a 1/8 rod next to it and run the ends from the top. That way the slow starters can still be getting juice while the rocket starts moving up the rail/rod. I have had great luck with a relay system where a topped-off battery is about 10', away. So there is very little losses due to long cable (complex rocket requires a further safe distance).

Relay used here too

LOC Tri-star on 3 38mm AT h45-w. [video=vimeo;157934332]https://Vimeo.com/157934332[/video]

Not sure where the link is???? Maybe getting a review?

 

[Leo]

Looking at some longburn clusters for my 4-29SS when warmer weather returns. How well does a CTI Mellow light in a situation like that? Considering the 3-grain 29mm G33's and the 4 grain H42's.

-Hans

On Sunday I flew my first G33 as sustainer in a 2-stage rocket. The ignition was instant.

 

[bobkrech]

Looking at some longburn clusters for my 4-29SS when warmer weather returns. How well does a CTI Mellow light in a situation like that? Considering the 3-grain 29mm G33's and the 4 grain H42's.

-Hans

CTI motors with starter pellets start promptly, but you have chosen 2 pairs of low thrust motors and you want to take-off on only 2. If one of the two motors does not ignite on lift-off, Houston you have a problem because the rod velocity is too low for a stable flight trajectory, so it's a no go by range safety rules for the following reasons.

The pad weight of your rocket will be at least 4.25 pounds and it is a complex J impulse rocket that requires a 200' pad separation distance. You propose to install (2) Pro29 3G 143G33 Mellow and (2) Pro29 4G 186H42 Mellow motors, and lift-off on 2 motors and then air-start the other 2.

Sorry but this flight, as proposed, is a no go by flight safety rules because: should you choose to launch on 2 G33s, your one engine out lift-off velocity is only 21 fps with an 8' rail (7' guidance length) and the rocket will be unstable; or should you choose to launch on 2 H42s, your one engine out lift-off velocity is only 28 fps with an 8' rail (7' guidance length) and the rocket will be unstable. The result of a timer-based air-start of either one or two of the remaining motors would result in an extremely dangerous horizontal or land-sharking trajectory.

The only safe way to launch this rocket with this motor combination is to ignite all 4 motors on the pad. Provided that at least 2 of the four motors ignite, the rocket will reach sufficient altitude above the rod to safely recover.

 

[HHaase]

Bob;

I haven't determined the final flying weight yet, but was mainly looking at the G33's and G42's as a full-quad at the pad or an air-started pair following something with more average impulse.
And I do run all my new rockets through a few different sim's, using actual Cg and weight, before any flights. I do appreciate the concern though as you're right .... all flights need to be safe.

Though it's going to be quite a while before I'm brave enough to try anything with an air-start. Still new to clusters.


-Hans

 

[watermelonman]

Honestly I am more comfortable with air starts than ground clusters.

Mellow is great for air start. 4x29, put two easy lighting high thrusters in there across from each other and air start a pair of mellows or smokers either right after burnout or coasting a few seconds. Sounds fun to me!