Adapting Madcow Terminator for Larger Motor Use?

[wyattjohnson35]

I want to buy, construct, and fly a 5" Madcow Terminator for my L3 with a 75mm motor mount someday. Due to the convergent section at the bottom, I am limited to 75mm. If I am to build this kit, I will build it was designed with the convergent section and fly with a 75mm motor to keep the cert fly low and slow. However, since it's fiberglass, I'd like to have some fun with it after my cert flight and use much larger motors. Considering that the entire motor mount assembly is going to be heavily secured with epoxy, would it be even viable to attempt rocket surgery on it and adapt it for 98mm or even a minimum diameter custom motor that I could make to make for fun. Once I have the 75mm assembly in, am I stuck with that for life?

(My thought was to chop off the convergent section, add some length to the front end, use a hole saw to drill it out to the desired inner diameter, insert the new MMT, and redo everything.) .

Anyone ever done this?

 

[DRAGON64]

You have my attention; I have a Madcow Terminator which sits un-built.

Either buy two and a build one stock, and mod the other for 98mm... Or, the only other option is to mod to 98mm motor mount, and adapt for 75mm. Don't de-construct on purpose, that which you can build now!

 

[mikec]

Depends on how much storage space you have for large rockets. Seems to me like it's easier to build a rocket that has a 98mm MMT to begin with if that's what you want ultimately.

 

[wyattjohnson35]

Depends on how much storage space you have for large rockets. Seems to me like it's easier to build a rocket that has a 98mm MMT to begin with if that's what you want ultimately.

The Terminator has plenty of room for a 98mm mount and up to around 124mm for minimum diameter, but the kit comes with a 75mm tube, 75mm centering rings, and fins cut long enough for the internal sections to fit the 75mm. Don't really want to spend another $500 or so, so I would have to buy 98mm hardware /centering rings and buy some kind of adaptor to bring the ID on the MMT down to 75mm?

 

[boatgeek]

It's always going to be easier to make the motor mount the size you want when you can fit up all of the pieces on a bench and not deep inside a rocket. If it was my project, I'd buy a piece of 98mm tube for a motor mount plus a couple of centering rings. The fin tabs can be cut back with a dremel pretty easily. That's probably also the route for the aft taper as well.

Before the first cut, I'd want to make sure the rocket will perform well with 98mm motors. You can get pretty close to a full M from CTI or Loki in 75mm. Can the rocket take an N without unreasonable nose weight? You probably have that down already, though.

[edited motor options]

 

[mikec]

Don't really want to spend another $500 or so...

You're going to spend a lot of money buying 98mm reloads anyway. Unfortunately I don't think Aeropack makes a 98mm tailcone retainer so you are going to have to lose the tailcone at 98mm unless there's some way to trim down the supplied tailcone.
I'm with boatgeek that it's easier to do this now than later by far.

 

[Keisling]

I recently built a Terminator and the inside diameter of the boattail was less than 4" at the aft end of the rear fin slots. I don't see any way a 98mm motor mount will work if you keep the boattail.

 

[blackjack2564]

Make the modification to 98 when you buy it. Madcow will probably let you upgrade to 98 mount & CR's very economically.
If you can.....order fincan longer to house 98 motors.If not order a 2-3ft section of pipe & coupler to make it longer yourself...easy peasy.
Mount a 98 motor retainer to small Cr..possibly a 98 coupler size Cr. that will determine how much to cut off tail cone.
I have done all the above mods on V-2's which are really tricky to do internal fillets.
You must think everything through and dry fit before gluing anything!
What you desire is very easy to accomplish if you have build experience on your side. One of the advantages of having been around the block a few times...lol

As a final note, there are many stylish kits out there that come with or easily upgraded to 98. Keep your mind open, you may find something that comes ready, and meets your desires out of the box, rather than trying to stuff 10 lbs in a 5lb box.

Good luck, have fun with your venture!

 

[wyattjohnson35]

I recently built a Terminator and the inside diameter of the boattail was less than 4" at the aft end of the rear fin slots. I don't see any way a 98mm motor mount will work if you keep the boattail.

My plan was to cut off the boattail

 

[Keisling]

If it were me, I'd just contact Madcow and see if they can put together Terminator-like kit with a longer booster, 98mm MM and no boattail. Or chose a different kit that didn't need to be chopped to achieve my goals. IMO, the boattail is a defining feature of the Terminator and it's just another split fin rocket without it.

 

[JDcluster]

In my opinion; it would be easier to build another booster than to hack it up.
See if they can make you one, using a stubbier boattail to accommodate the 98 mm?
I built one but, have yet to fly it. I bought it because of it's sleek look with the boattail

 

[wyattjohnson35]

I think I'm gonna get a 98mm MMT and some 98MM centering rings and just have an adaptor for 75mm use when needed (like for short test flights for dual deploy or other systems before attempting a super high flight at BALLS

 

[DRAGON64]

So, if you lose the boat tail by going 98mm motor mount, then that would leave you open to a couple split fin designed rockets that have 4" mounts; The Madcow Frenzy and the Wildman Dark Star Ultra come to mind. They run about $100 more than the terminator, but come with everything you need to build.

However, if you are hard pressed to have the Terminator outline, you may consider upscaling the terminator design to 6" airframe and see if that will work for you... The only end to bringing the imagination to life, is the amount of bank you have to contribute.

 

[wyattjohnson35]

So, if you lose the boat tail by going 98mm motor mount, then that would leave you open to a couple split fin designed rockets that have 4" mounts; The Madcow Frenzy and the Wildman Dark Star Ultra come to mind. They run about $100 more than the terminator, but come with everything you need to build.

However, if you are hard pressed to have the Terminator outline, you may consider upscaling the terminator design to 6" airframe and see if that will work for you... The only end to bringing the imagination to life, is the amount of bank you have to contribute.

No, you see, I already bought the terminator. I will probably build it as is w/o the boattail and use 98mm hardware with an interchangeable motor mount to fly 54mm and 75mm motors as well

 

[DRAGON64]

Should work just fine

"The Terminated"