Interceptor Upscale with a Twist?

[Bruiser]

So I have been thinking about taking a break from scale rockets and building a fantasy scale (I know, big jump, right?) rocket. I like the looks of Estes Interceptor but I really like BT-60 size models (mostly because Estes Star Orbiters have lots of parts that are great to cannibalize and they are readily available at Hobby Lobby cheap) but I also like the size

Anyway, I was looking on the web for plans and patterns when I ran across them for the original K-50 Interceptor plan. I also ran across this and I thought it was rather cool looking with the booster.



It got me to wondering if such a rocket was even possible for more than a static display. Could it work as a single stage with the engine in the booster? What if the engine was in the main body? If it could fly in this configuration, then a two stage is certainly possible...

What say my much-more-knowledgeable-than-me-rocketry-furom-colleagues?

-Bob

 

[prfesser]

It got me to wondering if such a rocket was even possible for more than a static display. Could it work as a single stage with the engine in the booster? What if the engine was in the main body? If it could fly in this configuration, then a two stage is certainly possible...

What say my much-more-knowledgeable-than-me-rocketry-furom-colleagues?

-Bob

I think it would be kind of difficult to get a straight flight with a motor in the booster. Likewise the drag from the booster might cause an arcing flight if the motor was in the main body.

The Interceptor G design is somewhat different from the original but would lend itself to boosters and/or clustering much more easily.

Best -- Terry

 

[Bruiser]

I had not seen the Interceptor G design until now. Is that an actual Estes design or a mod? I like it too.

-Bob

 

[Andrew_ASC]

Put enough thrust behind it and anything will fly! How it aerodynamically behaves under thrust is a whole nother story!!!!

 

[mikec]

It got me to wondering if such a rocket was even possible for more than a static display.

10x upscale with jettisonable booster. Alas, not a great flight video, and it was never flown in this configuration again.

 

[Bruiser]

so while I was waiting my turn to get adjusted I was surfing model rocket offset engines on my phone and I found a long thread. This person had a c motor in the Interceptor and a b in the booster. The way it worked was they would fire at the same time and off the rocket would go. The booster would burn out first and I guess drag separate from the Interceptor and deploy it's own chute. The Interceptor would burn a little longer and then deploy it's chute. The booster engine was angled at the cg of the rocket. They had two successful flights then they started to wonder what would happen if one of the motors didn't ignite. So they launched it with both engine in but only ignited the booster. I think they taped the two together and it flew. Then they tried launching it with only igniting the Interceptor and it arc'd right over and crashed. I searched for the thread on my laptop and I can't find it now...

I think I am going to abandon this idea and start thinking about two strap on boosters like pictured above with the Interceptor G. I'm thinking the same kind of thing as they used in the above example. Short burning engines in the boosters and a long burn in the Interceptor. Each booster would detach after engine burn and deploy it's own chute while the Interceptor would continue to go...

-Bob

 

[BABAR]

I have done a lot of asymmetric designs with good results, so IMO symmetry is overrated.

I think it would fly fine with a good strong single engine on the interceptor to kick it up to speed off the rod.
Before investing a ton of time into a finished product, seems like would be pretty easy to put together a close mock up (no paint, no sanding, no frills) and swing test it and if it passes fly it heads up to check viability.

Alternatives, put a short burn LONG delay engine in pod which will not separate but is permanently attached to the interceptor (say a B6-4 or A8-5 if those are still available) and a D12-3 in main, fire as a cluster, pod will deploy a chute AFTER main deploys. Has the advantage of redundancy, two separate independent chute deployments.

Not exactly the same, but close is what I use routinely for my long gap stage rockets, with a side engine pod on the booster with SHORT delay (still longer than the the burn time for the zero delay booster attached.). Cluster fire booster and pod on the pad, booster ignited and separates sustainer, pod fires chute. Works great. Never had one arc over due to asymmetry. Then again, like your design, the accessory pod engine is NOT very far off centerline. Whole different world if you put the pods at the outer fin edges.

Another option is put some extra finnage to balance out the asymmetry.

 

[Bruiser]

Here is the thread that I wrote about:

https://www.rocketryforum.com/threads/estes-interceptor-booster-kit.115771/

I've been looking for plans or .ork file for the Interceptor G to no avail. I keep going back to the picture in post 2. I'm not sure I like the way the pods obscure the view of the wing extensions and two booster pods will add a lot of weight to the rear of the rocket. Apogee does make a strap on booster kit though: https://www.apogeerockets.com/Rocket-Kits/Skill-Level-2-Model-Rocket-Kits/Strap-on-Booster-Pods

I think I am going to need to re-evaluate this project. I'm just looking for something cool that is safe and reliable to fly. I don't want to put anyone in danger due to a higher than acceptable chance that something will go wrong and I really want the rocket to survive launches.

-Bob

 

[prfesser]

I had not seen the Interceptor G design until now. Is that an actual Estes design or a mod? I like it too.

-Bob

North Coast Rocketry brought out the Interceptor G, long, long ago. In a galaxy far, far away... Was NCR a subsidiary of Estes?

I bought a water-damaged Interceptor G kit last year. Replaced one body tube and made basswood fins to replace warped ones. Pretty...but now I'm afraid to fly it.

 

[mikec]

I don't want to put anyone in danger due to a higher than acceptable chance that something will go wrong and I really want the rocket to survive launches.

Any time you are flying a cluster you are adding the failure mode that not all motors ignite. The farther from the centerline each motor is, the more likely it will be that the rocket won't fly vertically if this happens. You can be as careful as possible, use higher-reliability ways to ignite the motors, etc, but if you want to avoid this possibility, avoiding motors far from the centerline seems like the only answer.