Estes Pathfinder - turned up a notch

[Theory]

Build thread time but first a story. I vividly recall purchasing this rocket, an Estes Pathfinder with my Dad back in 1988. We were at a hobby shop in Washington DC, they specialized in model trains, that’s why we were there, but they also sold rockets. We had been flying for a few years and my Dad let me pick out a new one to add to the collection. The Pathfinder fit the bill nicely! I remember looking at the card on the front of the package, the excitement of my first “D” powered rocket was almost too much to handle. We flew her many times and she always turned in a good flight.

Thanks to Launch Lab Rocketry, I now have the opportunity to fly one again. In typical Theory Rocketry style, a few key modifications will be made to this one to ensure she holds up to some aggressive 24mm composite motors. I will “sleeve” the airframes with full length coupler stock from Balsa Machining, the motor mount will longer and incorporate 3 plywood centering rings, the fins will be cut from 1/8” basswood and coated in laminating epoxy. The recovery system will incorporate a Kevlar bridal, nylon shock cord and parachute and a nomex blanket.

A while back I did something similar with an Estes STM-012 and D-Region Tomahawk, and those have been an absolute blast to fly. Taking the same approach to this sentimental bird will be exciting to say the least!




The original parts. The BT-60 airframe is a touch banged up and will be replaced.

 

[Buzzard]

The model that I have been flying for decades. Have at least 3 more kits when this one makes it last flight. A true beautiful design for D12, E9, and E12 motors.

 

[NAR29996]

I built mine stock back in the day, and flew it on motors up to the F39. It's out in the garage somewhere.

 

[mn-rocketry]

A very classic design. I had a Pathfinder that I flew on D12-5 engines until it was lost to a cornfield.
I have two more of the kits tucked away in the closet, so I'll eventually build a replacement.

 

[Theory]

Made some progress! Got all the parts for the “turned up” version squared away.

Obligatory parts picture:


Next up is the airframes. Each airframe will be strengthened with a piece of coupler stock running the full internal length of the airframe. Note the upper BT55 coupler is shorter to allow the nose cone and transition to mate properly. The lower BT60 section has a full length coupler as I will be creating a custom bulkhead/transition set up to mate the two pieces together.



I like to use laminating epoxy when bonding the full coupler to the outer airframe. It’s thin, has a long pot life, and applies very well. Pro tip, you CANNOT use any form of yellow glue here. Titebond and others will “grab” the pieces as you slide them together before the assembly is complete. Ask me how I know… each coupler is well coated then I slide the airframe over and clean up the ends.




The last task was to mix up some medium weight expanding foam to fill the nose cone and transition



No pictures of the foam process. You can imagine what happened there. Measure well and there is minimal clean up after expansion.

 

[Theory]

Keeping my head down on this one. Hopefully will have it ready for the first Battlepark launch at the end of October.

Starting with a picture of the foam filled nose cone and transition and thickness of the coupler reinforced airframe:





Then it was on to the motor mount. At 5.5” long it’s just a touch longer than a three grain 24mm CTI case. Three centering rings will help distribute load. The retainer will be an aluminum unit from Rocketarium. I have these on all of my more serious 24mm builds. The Kevlar harness is exactly what the doctor ordered for a secure recovery system mount.







Titebond was used on the centering rings and to secure the motor mount in the airframe. Simple and crazy strong for wood/cardboard bonds.

 

[2-0turbo]

I bonded a 4” loc coupler in my Dare and after I cut the fin slots, wasn’t happy with the bond. I hope yours did better than mine. Next time I try this, I think I’m going to use gorilla glue/elmers like your bonding grains. And see how that works.

 

[Theory]

Sounds good. Gorilla glue expands a fair amount as it cures, not sure if that would be a negative when working with cardboard.

Thin epoxy has the benefit of being very easy to apply and can be absorbed into the material. It is also slippery and that helps slide everything together.

 

[Theory]

Got to work on the transition/coupler. Nothing really earth shattering here and that’s how I like my builds, simple and strong.

Starts with a positive anchor for the recovery system. Epoxied in a screw eye with very corse threads. This then gets a loop of Kevlar that will extend past the completed assembly.



Then take a piece of airframe and adhere that to the transition. I used a liberal amount of thin CA for this.



Inside this piece of airframe is a piece of coupler that runs from the open end to the transition. This gives an internal diameter that matches the booster. I then take a second piece of coupler and make a single length cut. This needs to be as square as you can get it.



Now insert that piece into a section of coupler allowing the sections to overlap. Mark the overlap as this will guide your second cut.



Cut out the small section and tack together with CA.



test fit and if all is good, bond in place with yellow glue



Once in place use the small piece you cut out to reinforce the joint. Slather with yellow glue and let dry.



And there you have it, a simple and strong transition to connect to “sleeved” airframe.

 

[Theory]

Also got to work on the fins. Gave each an airfoil and then soaked the airfoil edge in thin CA to add strength.



Tacked them on with good ol TiteBond





The upper assembly along with the booster.

Fin fillets and rail guides are next.

 

[Back_at_it]

Nice build. I like to beef up my builds as well. Some people go for lightness and altitude. I prefer to fly rather than fix so I build strong for the landing.

I haven't flown my Pathfinder in years as it needs a restoration but it was an excellent flyer on everything from D12-3 to F44-8's. It really screams on the F44's.

 

[Theory]

thank you!

 

[Theory]

Finally complete. The paint fought me every step of the way. That and, well, life was the cause of the delay.

With the recovery system installed, the weight w/o the motor is just a tick under 14oz.

Really excited to get her in the air. Right now aiming for the Battlepark launch on the 10th and 11th.

 

[2-0turbo]

H268? Not sure if that has a 29mm mount in it or not, but figured I’d ask.

 

[Theory]

It’s a 24mm, but no worries, full tilt 6grain G motors are 100% on the table

 

[Back_at_it]

Finally complete. The paint fought me every step of the way. That and, well, life was the cause of the delay.

With the recovery system installed, the weight w/o the motor is just a tick under 14oz.

Really excited to get her in the air. Right now aiming for the Battlepark launch on the 10th and 11th.

View attachment 687170

Very nice build. Makes me want to rebuild my tired old model.

 

[Theory]

@Back_at_it Thank you!

 

[Papa Elf]

What? No 38mm motor mount? You haven't Turned It Up A Notch then Seriously though, cool rocket. One of my all time favorites! A kit Estes should bring back

 

[neil_w]

Very nice.

 

[cwbullet]

I love this rocket - nice build.

 

[Theory]

@cwbullet Than you!

 

[Theory]

Got her in the air this weekend for two successful flights. The first on an E26 then on an F41. Very happy with this project!