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angrymeat

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I am building a 42 inch long rocket 3 inches in diam I am going to use 4 x c6-5 engines in this my question is about the engine mounts . Should I make them a standard size or should I make them longer due to the long airframe ?


As to why I am clustering this rocket well my local walmart had c6-5 engines on sale for $1 a pack so i have 50 or so of them . I would like to eventually mount a camera on this rockets which is another reason I went with 4 engines.
 

Micromeister

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I am building a 42 inch long rocket 3 inches in diam I am going to use 4 x c6-5 engines in this my question is about the engine mounts . Should I make them a standard size or should I make them longer due to the long airframe ?


As to why I am clustering this rocket well my local walmart had c6-5 engines on sale for $1 a pack so i have 50 or so of them . I would like to eventually mount a camera on this rockets which is another reason I went with 4 engines.
I perfer clustering BP motors to using a single apcp motor anytime;)

I think what your referring to as extending the motor mount is more correctly a stuffer tube, but this well not mean you simple extend all for motor tubes.
I usually use a couple as a transition between the motor mount and stuffer tube making an ejection chamber if you will. this allows your stuffer to say a bt-55 or 60 to be mounted in an epoxy covered plywood centering ring on the forward end of the coupling with the clustered motor mount centering ring on the aft end. by coating the inside of all the parts with epoxy you will greatly extend the life of the ejection chamber and useable life of the model. some of my clustered bird have had as many as 30 flights before needed a motor mount rebuild.

In the pic below of my 4 D12 clustered OT you should be able to see the motor tubes, BT-80 coupling (ejection chamber) and in this case a BT-60 stuffer tube used to reduce the amont of gases needed to deploy the laundry.
Hope this helps.

149h1-sm_Ultra OT After repairs_04-20-07.JPG


s In & tested_04-20-07.JPG


s Cluster Close_04-20-07.JPG
 
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angrymeat

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thank you very much for the information it was very helpfull I will work on that now . I love to scratch build things vs use a kit and I just got into this again last week so I am catching up on the terminology :) . I was very worried that with the overall size of this airframe that it wouldnt be enough to eject and poof I end up with a 42 inch torpedo :) I salvaged the nosecone from a big daddy kit so outside of that all I have invested in this build is the $4 for the shipping tube that makes the body and $3 worth of 1/8 inch balsa . The chue is actually an 18 inch nylon chute I found in a $1.50 kids toy that I have tested and works very well already . I will post some pics up as soon as I build this chamber .
 
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angrymeat

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so i launched it with a 3 engine cluster i had made before today to take advantage of the kids being out of town for the afternoon. lets just say 3 engines are not enough at all for the weight :) not to mention i need to make a stronger engine mount it ripped free and shot into the body at some point . It did make it about 400 feet but the 5 second delay let it deploy chute about 3 feet up . Damage wasnt bad it will now be about 4 inches shorter .
 

BsSmith

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so i launched it with a 3 engine cluster i had made before today to take advantage of the kids being out of town for the afternoon. lets just say 3 engines are not enough at all for the weight :) not to mention i need to make a stronger engine mount it ripped free and shot into the body at some point . It did make it about 400 feet but the 5 second delay let it deploy chute about 3 feet up . Damage wasnt bad it will now be about 4 inches shorter .
Time for side pods! About 6 of em'.
 

FlyBack

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Movie quote comes to mind...

"Ya think you used enough dynamite there Butch?"

FlyBack
 

dpower

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so i launched it with a 3 engine cluster i had made before today to take advantage of the kids being out of town for the afternoon. lets just say 3 engines are not enough at all for the weight
What type of BT did you use, and how heavy is the rocket? With a 3" thin wall BT, I would expect in the neighborhood of 10oz, for which 3 or 4 C6 motors would be enough for respectable altitude. Download one of the free RASP (I use wRasp & pRasp) programs to get a rough idea of how much motor power you'll need:

http://www.thrustcurve.org/simulators.shtml

Here is pRasp, for the palmOS:

http://members.shaw.ca/whortens/
 

Meat

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hmm site wont let me in the old account had to make a new one .
The body tube is actually a Shipping tube so its a little thicker than a normal BT which add s some weight . When I put it all together in rocksim it comes out to about 23 oz so its pretty heavy. I not have a 7 engine cluster build into it for fun. I also rebuilt the fins on it to give them a forward slanting look which I have no idea how well that will work. I plan on a test flight and most likely crash tommorow :).I am wanting to get started on a sidewinder or bulpup scratch build but cant put this damn thing down .

32 inch.jpg
 

rokitflite

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Cool looking rocket.

Do you have any build or flight threads on this?

Would love to see more pictures or video.

Nope... It was 32 Cs and a D chad staged to 32 Cs and a D. There was a CATO of one of the top engines (one of the 7 that pressurized the ejection compartment) so all of the ejection charges escaped through the hole left by that motor. It hit Lucern Dry Lake at terminal velocity with a super 8 mm camera in the nose... R.I.P.
 

Meat

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If i dont find a day that the wind lets me launch this big bastard I will be
 

rcoffee

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I LOVE that OT. I am flying mine on a 2 engine c cluster. I see I will have to upgrade. I want a big booster so I can conver me glider to and R/C
 
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