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  #1  
Old 09-07-2011, 11:47 PM
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bernomatic bernomatic is offline
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Question Next up: Renegade D

My next build is going to be an Estes Renegade. I built the staged version before but never got to fly it

I sent for a new kit from Estes to find out that they had updated the kit to single stage with D engines.

I definitely don't want it to be single stage and plan on adding a chute or streamer to the booster to solve the recovery problems I've read about for that stage. This bird was meant to fly on two stages however, you can just feel it.

My questions are:

1) should I make make it a 18mm two stager or a 24mm two stager.

2) Do you think it is necessary to shorten the booster BT to help thrust.

3) Any other suggestions or hints. (maybe not using the Estes standard staging technique, but using seperated engines. etc.)

I mostly launch at football size fields so I'm leaning to the 18mm size, but wonder if I'm limiting myself.
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  #2  
Old 09-08-2011, 07:17 AM
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Quote:
Originally Posted by bernomatic
1) should I make make it a 18mm two stager or a 24mm two stager.
<snip>
I mostly launch at football size fields so I'm leaning to the 18mm size, but wonder if I'm limiting myself.
Make it 24. There is no 18mm motor suitable for lifting this thing. It was an awful mix (of weight and thrust) in its original incarnation. If you're gonna fly it in that configuration, use the 24mm C11 booster. That way, you'll have enough thrust to get it going but low enough impulse to still keep it on the field.

As for the sustainer, make it 24mm, too. You can still fly smaller motors in it using spent 24mm casings as adapters. For example, I've staged C11-0's to A8-5's that way. Again, this will help keep it on the field.

Doug

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Old 09-08-2011, 09:33 AM
stefanj stefanj is offline
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I am in the same boat. I like the idea of a two-staged Renegade, but the original design didn't cut it.

Vents for staging gasses would be a good thing to add.

Any suggestions as to how to ensure the booster parachute deploys? Just loosely pack it around the top of the booster motor tube and hope for the best? Putting it at the end of a foot of shock cord might encourage it to snap open.
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Old 09-08-2011, 09:49 AM
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Any suggestions as to how to ensure the booster parachute deploys?
This gives me an idea to go a different direction. Instead of using a 24mm booster, another option is to go with 18, and use a cluster. It's more complicated, but I've had great results.

In this case, the center booster motor would stage to the sustainer while another, outboard booster, with delay, could be used to deply a chute or streamer. As I recall, this booster has some pods which could house the recover system.

But you wouldn't want a booster motor that far off center - too much potential for mayhem.

So some more work would be required to reconfigure the booster (without killing it artistically) to accomodate the outboards.

The upside is that this booster tended to be stable, which makes it better suited for use with a recovery system. (Ejecting a chute from a tumbling booster makes for tangled mess )

Anyway, there's a couple more cents thrown into the mix

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Old 09-08-2011, 10:29 AM
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So some more work would be required to reconfigure the booster (without killing it artistically) to accomodate the outboards.
Okay, I found a pic on the web. There are two sets of outboards. The farther out ones are what I was envisioning earlier. But there is a larger set of what appear to be BT-20 tubes adjacent to the main booster airframe. These would be perfect for a pair of outboard motors and recovery system. No aesthetic compromises required.

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Old 09-08-2011, 11:19 AM
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I've read somewhere else on the web that someone converted the BT20s for 13mm engines, not to give any significant thrust, but for recovery parachute deployment in the booster. That would be keeping in line with my small field requirement, but now I start to worry about stability. I found a rocksim file for the Renegade (after I started one myself) on Rocket Reviews.com, but it is in an older version and doesn't have the outboard booster pods, so I'm in the process of reconciling the two.

I know I could just slap about a pound of clay in the nose cone, but I think I can do better than that.
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Old 09-08-2011, 11:47 AM
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Quote:
Originally Posted by bernomatic
I've read somewhere else on the web that someone converted the BT20s for 13mm engines, not to give any significant thrust, but for recovery parachute deployment in the booster.
Keep in mind, you can still get a full A in the 13mm form factor. That is, these motors are non-trivial.

In this case, a pair of 1/2A3-xT outboards will help get the heavy rocket off the rod without overflying the field, but it's necessary for the outboards to have a total burn+delay time greater than the center motor so that the rocket stages before booster recovery deployment. So a pair of A10-3T outboards might be in order (to go with an A8-0 in the center). But a pair of 1/2A3-2T's might work, too. I need to check the thrust curve and delay time data.


Quote:
That would be keeping in line with my small field requirement , but now I start to worry about stability. I found a rocksim file for the Renegade (after I started one myself) on Rocket Reviews.com, but it is in an older version and doesn't have the outboard booster pods, so I'm in the process of reconciling the two.

I know I could just slap about a pound of clay in the nose cone, but I think I can do better than that.
Yeah, I thought about that, too. You want to booster to be stable, so you might have to add a bit (not a pound ) of weight to it forward, but you're also adding weight to the aft end of the overall rocket, so you need to watch that, too. It would be painfully ironic to make the rocket unstable while trying to make the booster stable

Doug

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Old 09-08-2011, 02:03 PM
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Okay, I think my RockSim design is a little more accurate than the Rocket Review one due to using RockSim 9.0. The other design doesn't show the nose weight. Anyhow, using my file with just the single stage and D engine, I get a margin of about 3.08.

Making it a 2 stage and using E's (just to throw the weight up at the rear), I get a margin of 2.13.

These are preliminary results as there are some minor(?) corrections I need to make to the file, but it looks like we may be a go for SRB throttle up.
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What's your idea on the best way to change Washington D.C.?
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  #9  
Old 09-08-2011, 02:29 PM
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As I started looking at the boosters I noticed that they were BT 50s, so....... just for S & G, I loaded E9s in each booster. Computed altitude was around 4200. Margin was 1.09. Boy would I like to see that flight.
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What's your idea on the best way to change Washington D.C.?
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  #10  
Old 09-08-2011, 02:31 PM
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Quote:
Originally Posted by bernomatic
As I started looking at the boosters I noticed that they were BT 50s, so....... just for S & G, I loaded E9s in each booster. Computed altitude was around 4200. Margin was 1.09. Boy would I like to see that flight.
You can see the first half of it from the ground. The second half, you'll need radar

BTW, if you really do build a clustered booster, make sure you use a burn string.

Doug

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