L2 Design and Build...4x Upscale EAC Viper.

[MarsLander]

Me: Early 70s BAR x2. Rocketeer 70-82, BAR 1998-2005 (L1) Kids, now BBAR 2023 with Grandkids...starter sets for Christmas!

LDRS Hotels booked for URRG in NY for 2024. Level 2, LDRS or before...

Lots of contemplation on what to build and how. Lots of rocket and non-rocket FG experience. Design criteria:

1. Upscale Estes.
2. Something someone has not done at target upscale size.
3. Fly on I-J K(see below). (Mid 1K I through 63K (see below) capable as Skybusters.org NAR #535 is limited)...say, do both local and national launches.
4. From a cost perspective, it really doesn't matter, but follow the KISS principle (Electronics not required for L2).
5. Something cool, but not *super* complex like a Mars Snooper.

Landed on a 4x EAC Viper 4X Upscale.



4x Upscale is a 39" x 4" FG airframe with 4:5-1 VK NC. Wildman Fiberglass components, G10 .125 fins, stickershock23.com decals.

Details:
CG: MAC Performance nosecone bay kit allowing the addition of NC weight and altimeter, and MAC Performance and SC Precision thrust plates (1.8 oz and 4.8 oz). Swap thrust plates depending on motor (lower weight for higher power and higher weight for lower power to keep it stable.)

Recovery: Nose cone/Motor ejection. Drogue-less, Jolly Logic CR/50" Recon Recovery main, with One Bad Hawk Y booster harness and 30' harness.

Design done, parts ordered...for the most part.

Let me know your thoughts/input. I have no pride of authorship and welcome all feedback!

MarsLander

 

[sharkbait]

Me: Early 70s BAR x2. Rocketeer 70-82, BAR 1998-2005 (L1) Kids, now BBAR 2023 with Grandkids...starter sets for Christmas!

LDRS Hotels booked for URRG in NY for 2024. Level 2, LDRS or before...

Lots of contemplation on what to build and how. Lots of rocket and non-rocket FG experience. Design criteria:

1. Upscale Estes.
2. Something someone has not done at target upscale size.
3. Fly on I-K. (Mid 1K I through 6K capable as Skybusters.org NAR #535 is limited)...say, do both local and national launches.
4. From a cost perspective, it really doesn't matter, but follow the KISS principle (Electronics not required for L2).
5. Something cool, but not *super* complex like a Mars Snooper.

Landed on a 4x EAC Viper 4X Upscale.

View attachment 615657

4x Upscale is a 39" x 4" airframe with 4:5-1 VK NC. Wildman Fiberglass components, stickershock23.com decals.

Details:
CG: MAC Performance nosecone bay kit allowing the addition of NC weight and altimeter, and MAC Performance and SC Precision thrust plates (1.8 oz and 4.8 oz). Swap thrust plates depending on motor (lower weight for higher power and higher weight for lower power to keep it stable.)

Recovery: Nose cone/Motor ejection. Droguless, Jolly Logic/50" Recon Recovery main, with One Bad Hawk Y booster harness and 30' harness.

Design done, parts ordered...for the most part.

Let me know your thoughts/input. I have no pride of authorship and welcome all feedback!



MarsLander

Love the EAC Viper, I did a 6” one with glassed PML phenolic, dual deploy and the one mistake I made was using a 54mm mount, should have gone with a 76mm mount. Mark did my decals too and he talked me into a slight variant and made a Hyper-Viper logo for it. This sounds like a cool project and 54mm mount would be perfect for yours, I am patisl to DD but I understand your want to keep it simpler and easy to fly

Good luck and post build pics if you can

 

[MarsLander]

Thrust plates are in. They weight 1.8oz and 4.9oz...just about spot on.

Nose cone bay also in, weights about 60 grams less than I expected. OBH harnesses are super nice!

 

[MarsLander]

More goodies arrived!

 

[tg08]

This is gonna be a good build! Best wishes.

 

[MarsLander]

Waiting on some pieces/parts, and epoxy.

Cut and squared the MMT. I don't have much rocket experience with FG...lots of FG with other hobbies. Wrapping the tube at least 4X with tape reduces edge splintering significantly and gives smooth/square results (pats my own back). Spot on with length and tube is square:


Having some fun with the Jolly Logic Chute release (@John Beans ). Played with AT LEAST 3 packing techniques. This pack allows the shroud lines to release easily and first, unfurls the gores, the the top releases. Bands with the JLCR are just a bit small for the 50" Recon Recovery chute from @WILDMANRS. Had to go with aftermarket .39x3.15 EDPM. They work great. This is AFTER VIOLENT shaking:


About to pack up with @mike2wander Wildman nosecone bay for GPS and altimeter and @Onebadhawk harness. Self wound kevlar, and marked for future wind and taping (center and tape lines). Fits like a dream in the 4" tubes. Yes, I will X tape thinner when the time comes. Ordered an 8"x3" @jahall4 sled for the JLCR.

3.5 Xs of tape to get nose cone to friction fit. Thanks @Handeman!


Clearly have the recovery package sorted...until I don't...(Yes, rubber band is just for the picture).

Finally, downloaded the 3D print file of the @KC3KNM Tube squaring tool (https://www.rocketryforum.com/threads/3d-design-constest-kc3knm.147558/) and ordered a 3D print online. Thanks for the design!, hope it works, the HED end of this airframe tube is OFF SQUARE!

 

[MarsLander]

Parts washed. Custom jig built (had to plane this crappy Menards wood...PITA) that will allow me to tack rear and forward fins at the same time.

Sized inner and outer CR dimensions. Front 2 CR are nicely tight...rear is looser to allow removal for rear entry for interior filets. @Onebadhawk harness drilled.

 

[MarsLander]

Tell me you are anal about centering ring square and placement without telling me you are anal…


Tacked with thin CA, then first two rings epoxied…

 

[MarsLander]

Weld nuts are on for thrust ring. Have to adjust them for airframe and 4 fins…

 

[86mustang408w]

Awesome build, im checking out L2 cert builds myself some more. Good luck, very nice.

 

[MarsLander]

Side bar...these fins are a bit of Dumbo Ears, short(ish) root cord and large(ish) AR. Investigating flutter. Top end J motors and low end K motors likely will induce flutter. Would like to run this on I-K motors, but running into flutter problems around (390-440mph) based on sims. G10 1/8" will narrow the motors to top of I to lower to mid J. May need to upgrade 1/8" G10 to 3/16" G10. 3/16" G10 gives me room to 720mph at 5000ft. While it may limit altitude, it will provide a wider range of motors.

Fin design matters. Ha! #alwayslearning.

More info:

1. EAC Viper flutter!
2. Flutter Tools for you!

 

[David Schwantz]

How did you prep your glass for glue?

 

[MarsLander]

How did you prep your glass for glue?

Acetone, 120 both ways until lots of white powder, acetone, 120 again, acetone. I usually look for the shiny reflection to disappear. If I'm feeling randy, I might even water-break test, but I can usually tell by the visual.

 

[MarsLander]

Ok, after this foray into flutter: (L2 flutter and design) and creating some flutter tools for everyone (Flutter tools for you!), I’m back to building…

I tried to get "Cute" and used "C" type lock nuts on my harness. They galled the eye bolts to the point of failure. Lesson learned. Ordered a new harness from @Onebadhawk who admonished me he could have fixed them, if I hadn't cut off the hardware. Reverted to locking nuts and nyloc/epoxy...tried and true. Lesson learned. @Onebadhawk is a super guy and I'm still learning. #alwayslearning.

Attached the harness. Waiting for it to cure…

 

[MarsLander]

How did you prep your glass for glue?

Something else I should be doing?

 

[David Schwantz]

I just did not see any sanding marks was all.

 

[MarsLander]

Working on the business end. @mike2wander and @SCP thrust plates. SC Precision come set. Had to drill, tap and countersink the MAC performance to match so I can interchange. Easy!

Word to the wise, aluminum can gall when cuttting threads. Use TAP Magic aluminum cutting fluid, clear your tap often, and always cut 1/2 turn, 1/2 turn counterclockwise, repeat. Especially with small threads.

 

[SCP]

Good advice on tapping aluminum. You shouldn't have had to do anything on the SCP plate right? If so that's my bad as they should always be 100% ready to go.

NICE BUILD!

 

[MarsLander]

You shouldn't have had to do anything on the SCP plate right?

SC Precision come set.

NICE BUILD!

Thanks! More thinking than building to this point, should go faster now...

 

[MarsLander]

Started prepping for building the AV Bay and epoxying the MMT. Ran into a quandary on how to vent this AV Bay.

 

[MarsLander]

Been a moment. Needed to move operations out of the kitchen. Had 60k BTU heater installed and added a new bench to the garage. Viper migrated!

 

[MarsLander]

Slinging Six10. Motor mount epoxied in, and NC shoulder MAC performance Avbay epoxied together!


Sprayed some primer on a spare FWFG tube because I wanted to test some colors. I've never seen SEM spit like this. Can was warmed, rattled for 2 minutes, and "presprayed" for a couple seconds before it hit the part. Never had this happen...Thoughts?

 

[MarsLander]

First fin on…

 

[MarsLander]

Second fin on!

 

[ecargmij]

Awesome build I've always liked the EAC Viper

 

[ecargmij]

I may need to make a 3" version.. I prefer FG myself..

 

[allensmith]

Oh man! I’ve been wanting to build one of these for a while. Loved mine when I was a kid. Looking to do some kind of upscale. Really enjoying your build. Keep up the good work.

 

[MarsLander]

Third fin on! First canard on!

 

[David Schwantz]

How are you attaching fin to MMT? Also what kind of set up are you using to align fins to tube? I see your angles with clamps, but what keeps them 90 degrees to each other? Love to find something fool proof.

 

[MarsLander]

How are you attaching fin to MMT?

JBWeld

Also what kind of set up are you using to align fins to tube?

Main fins:
2 - 2x6s that were planed and a 45 degree bevel cut into one side. Place some material that is same thickness between the two and lock it down with bolts/nuts. The underside 2x6 is longer so that you have a space to slide fin into rocket and clamp to keep 90 degrees.
Canard:
2 - 1/2x1/2x1/8 angles. Rubber bands at the back and chip clip on the canard. The fins are long enough it maintains a straight line from the fin to the canard.

I see your angles with clamps, but what keeps them 90 degrees to each other? Love to find something fool proof.

If I understand, the answer is...the 45 degree bevels keeps the tube straight with the fin slot. The rubber bands and the bungies keep it in general 90 degree alignment. For final adjustment, when I can slide the fin into the slot without interference, I use the blue tape to lock the 90 degrees. I'm sure the bungies/rubber bands keep it 88/89 degrees or better, the blue tape locks in the 90.