Bull Pup

[pcec]

I have the Estes Bull Pup kit. I was going to fly on an E-12-6 motor in stead of C-6-5. Changed the engine mount out to fit it. Was going to add weight to the nose cone for stability. Any advice?

 

[Bruiser]

I suspect it'll need the nose weight. Maybe you should sim it in OpenRocket or another program.

It has two features that shift the CP back. FOrward fins and a boat tail

-Bob

 

[pcec]

I suspect it'll need the nose weight. Maybe you should sim it in OpenRocket or another program.

It has two features that shift the CP back. FOrward fins and a boat tail

-Bob

Never heard of openrocket. Thanks!

 

[Bruiser]

It's a wonderful tool and there are many people on this forum board that can help if you need any.

Also another wonderful resource is K'Tesh's OpenRocket files. You'll find them over in the "Plans" thread here: https://www.rocketryforum.com/threads/kteshs-openrocket-files-index.148212/ You won't find more detailed or accurate files anywhere. Unfortunately, the Bullpup is not one he has done but there are many, many others.

-Bob

 

[rcktnut]

I simmed it for you in RS, you'll need 1.5 oz nose weight, 8 second delay, pretty big launch field and very good eyesight. 1700 ft on that motor. Get Open Rocket which will be great for simming all your rockets.

 

[pcec]

It's a wonderful tool and there are many people on this forum board that can help if you need any.

Also another wonderful resource is K'Tesh's OpenRocket files. You'll find them over in the "Plans" thread here: https://www.rocketryforum.com/threads/kteshs-openrocket-files-index.148212/ You won't find more detailed or accurate files anywhere. Unfortunately, the Bullpup is not one he has done but there are many, many others.

-Bob

Cool thank you

 

[pcec]

I simmed it for you in RS, you'll need 1.5 oz nose weight, 8 second delay, pretty big launch field and very good eyesight. 1700 ft on that motor. Get Open Rocket which will be great for simming all your rockets.

Awesome thanks. Question this particular Estes model came with clay weight for the nose cone. I didn’t weight it. But I’m assuming it would need 1.5 oz in addition to what came with the kit already?

 

[Back_at_it]

I would add an additional 1.5oz. That rocket is barely stable with the included nose weight when built stock.

I added an additional .50 oz to my stock build after a couple of less than perfect flights. I mostly fly it on C6-3’s now but an occasional B6-2 has used for small parks

 

[rcktnut]

I started with 2.0 oz total weight= 2.04 stability margin with motor. Then I tried 1.5 oz total weight, ended up with 1.52 stability margin. It lost 65 feet of altitude, with 2oz. so not much difference in altitude. With both weights rocket flew nice and straight. Either way up to you. I have that model also and did exactly the same thing as Back_at_it did, added .5 oz more clay to my also stock built model. I use clay on all my LPR rockets ( if needed), bought a chunk from Hobby Lobby. I pack it in the nosecone with a wood dowel. Maybe start with 1.5 oz. see how it flies. Much easier to add than remove!!

 

[pcec]

Successful flight. Stable and straight up. A little damage on landing. Tail piece melted off. But thanks to everyone for advice.