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Feyd
04-12-2010, 10:52 PM
This is not complete, but the basics are there. It's a two-engine cluster with rear ejection (how do I do that?). I would like to add a couple of fins in a "v" shape over the engine pods so they're sticking out the side of the rocket but I don't know how to do that.

I thought there used to be baffles in RockSim9, but now I can't find them. The rear engine block is supposed to be a BT-80 baffle. Also, I wanted to add a nosecone at the rear of the rocket instead of the transition. And I want to add the same nosecone at the rear of the outer pods.

In any case, this is a first draft of the design.

What do y'all think?

CPMcGraw
04-12-2010, 11:52 PM
This is not complete, but the basics are there. It's a two-engine cluster with rear ejection (how do I do that?). I would like to add a couple of fins in a "v" shape over the engine pods so they're sticking out the side of the rocket but I don't know how to do that.

I thought there used to be baffles in RockSim9, but now I can't find them. The rear engine block is supposed to be a BT-80 baffle. Also, I wanted to add a nosecone at the rear of the rocket instead of the transition. And I want to add the same nosecone at the rear of the outer pods.

In any case, this is a first draft of the design.

What do y'all think?

I think it's a winning design, Feyd.

Is this what you had in mind when you said "v" shape over the engine pods?

We have a number of reversed nose cones already in the transitions file, but what you do is just copy the info from a standard NC into a custom transition, make the front diameter the same as the tube, and make the "rear" diameter something like "0.00001" instead of just "0". Match the shape. Copy the shoulder info, too, but remember it's now the "front" shoulder. Clear the "rear" shoulder values.

Feyd
04-13-2010, 06:59 AM
Almost... I was envisioning the fins closer to the body tube. Also, I was thinking of canting the engine pods into the main tube. I thought that would make the look more interesting but I don't think you can do that in RockSim. I may do away with the "V" fins and make the upper and lower fins larger and more "raked". I'll play around with it some more.

Thanks!

Feyd
04-13-2010, 07:17 AM
Here's what I mean about the fins. I've modified the two fins at the bottom of the component list to look more like what I was thinking, and I figured out how to move the fins closer to the main body tube. Plus with those additions, the speed at deployment is now under 2.

Thanks for the assistance!

(Alternate daytime email address: dale.marshall@us.af.mil)

Feyd
07-01-2010, 06:39 AM
Well, it's about time to start building this beast for the EMRR challenge. I'll likely work on it over the weekend. Any suggestions/tips for painting? It's got a lot of components but I haven't dreamed up a paint scheme for it yet.

Suggestions are welcome!

Another question... I'm considering using composite engines because that would earn me more points in the contest and more power is always good :) Considering I'm using 24mm tubes for engines mounts, and I don't have a Level 1 certification, what engines are recommended?

CPMcGraw
07-01-2010, 08:27 AM
Well, it's about time to start building this beast for the EMRR challenge. I'll likely work on it over the weekend. Any suggestions/tips for painting? It's got a lot of components but I haven't dreamed up a paint scheme for it yet.

Suggestions are welcome!

Another question... I'm considering using composite engines because that would earn me more points in the contest and more power is always good :) Considering I'm using 24mm tubes for engines mounts, and I don't have a Level 1 certification, what engines are recommended?

There are composite D-E-F-G engines which I think would fit in the 24mm tubes, and which do not require any certification. The rules changed last year, so I'm not fully up on what the requirements are for G and beyond.

Les
07-01-2010, 09:49 PM
Cool design. Any concern on the engine exhaust damaging the rear transistion?

You also want to post a pix that those without Rocksim can see it

STRMan
07-01-2010, 10:19 PM
You also want to post a pix that those without Rocksim can see it

Thank you.

Feyd
07-01-2010, 11:20 PM
you asked for it, you got it!

Some changes - I made the fins all the same size and I moved the two engine pods rearward. I also removed the rear nosecone and small tube section and moved the parachute forward. I had originally made this a rear-ejection model but I've change my mind and made it a standard type ejection, and added a baffle below the parachute. I may make it dual deployment since the top part is so long.

Comments and suggestions are welcome.

Feyd
07-02-2010, 05:04 PM
First try at adding color. I don't want to overwhelm the rocket with lots of different colors, but I don't want it to be boring either. Likely I'm going to have to paint much of it before I put the fins on.

JRThro
07-02-2010, 05:26 PM
Thanks for the pictures! It looks good.

I'm still not clear on how the fins and various tubes are arranged. Could you post some other angles, or a shot from the back end?

Feyd
07-02-2010, 09:15 PM
Here are a couple more angles.

Feyd
07-02-2010, 09:17 PM
Here's another color scheme that my wife worked up.

Feyd
07-04-2010, 02:01 PM
I've started building this monster. It's going along well so far but I'm out of primer and pretty much everything is closed today so I'll have to wait until tomorrow to prime everything. Still deciding on a paint scheme though. I'm considering painting everything before putting it together so the masking won't be as hard. I'll have to mask off all the contact points, but I don't think that will be a big deal.

I am going to make it dual deployment, with a 12" parachute for the nose section and an 18" parachute for the tail. I'll have to weigh everything to make sure the chutes aren't too big.
Actually, I split it into two stages in Rocksim. The top part, not including the parachute, is 1.97 oz. The bottom part is 7.82 oz without engines. EMRR's parachute calculator says 10" to 13" for the top part, and 20" to 26" for the bottom part. So I guess I need to find a 24" parachute.

Question... do you think a baffle (see 2nd picture) will be needed given I'm doing ducted ejection and the size of the tubes? I'll be putting a solid ring below the ducts in the main tube to keep the gases moving in the right direction. The duct holes are about 1" x 1/4".