Estes Quark 4.81x Mid-Power Upscale

[RobertH3]

Got this finished yesterday and think it turned out fairly good. Here are the stats:

Upscale Factor: 4.81x
BT-5 to BT-80 (2.6") tube; BT-80 is 8.5" long thin wall (8.4375" for perfectionists)
Nose Cone is an E-Rockets BNC-80G4 thin wall (2.6" 4:1 Ogive) - perfect for this model
Motor mount/rings are an Apogee 29mm - 2.6" - I left the thrust ring out in case I go big someday
Retainer is an Estes 29mm special - light weight, low cost
Overall height sitting on fins: 27"
Fins: I up-scaled using the copier method (original fin on copier, then take the copy and enlarge to 481% : ) - easy
But here are the measurements
Root and tip: 5"
Leading and Trailing Edges: 8 3/4"
Sweep angle: 60 degrees
Thickness of stock (perpendicular leading to trailing edge) 2 1/2"
TTW tabs for BT-80 to 29mm motor mount tube - I made mine a little large, and sanded them down until flush

Decals: your vendor of choice. I have tried them all and all are GOOD.

I tried a new fin build on this kit - 1/8" balsa wood with 1/32" plywood skins glued on. Super strong, very light, but a little difficult to shape a leading and trailing edge. I discovered that dollhouse people have 1/8, 3/16. and 1/4" half rounds made of basswood - if you're into epoxy Plastruct makes some plastic ones for modeling. This worked great on leading edge but made the fin a little wider than perfect scale. It is tough to get the basswood on straight - it is a little warpy and some puttying is needed. Trailing edge reinforced with thin quick dry super glue.
I double-anchored some heavy Kevlar thread in the forward centering ring, making a loop that is inside the body tube (like a Boyce kit), and 4' of heavy duty shock cord - I may double it to 8 feet, it stretches 2x. Don't need a nose cone - body collision at apogee.
Stability - I built this on Rocksim and it was stable w/o any changes. Still, I added an ounce of BB's to the nose cone by drilling a hole, loading with glue, and installing a dowel. Also made a nice anchor point for the screw eye.
1.7 Cal stable empty, and 1.4 Cal stable with a G-80 or G125. I picked heavy motors on purpose.
Cp on this rocket is 1/2" up from the bottom end of the body tube, and Cg is right around where the leading edges of the fins attach to the body tube. Due to the design, the motor (lengthwise, including fins) is near the center of the rocket so Cg doesn't shift a whole lot. Dang, this hobby rocks now with the software, Web info, and new books!!!!

Maiden flight will be F26-6FJ second flight will be F50-6T - both to 1000-1200 feet, 6 second delay is near perfect.
On motors, with the super long fin chord, G80 is pushing it and G125 is possible flutter/airframe failure (near 500mph) at 1900 to 2000 feet altitude.

Shortcoming (literally) - very little room for the recovery stuff. The E-Rockets nose cone only has a 1 1/4" shoulder, but it will be a tight fit with dog barf, the cord, and a 24" Estes parachute. There is also the large F/G ejection charge bang, maybe a really long cord! Still, it looks really good and SHALL fly. Here are the pix:

Cheers / Robert

 

[markschnell]

That's really well done. I have an upscale Quark too, same size, though I stuck with the 24mm mount. It's one of my favorite flyers. With those wide set fins I've had it come down a do a perfect four point landing more than once.

 

[RobertH3]

Some of them fight you the whole way and some just go together - this one just went together. Surprised, when I work one up there are usually issues. Easy build, easy finish. Nice spin on 4FNC. I thought about 24mm but since I have a pile of F26-6 and F50-6 (Estes by Aerotech) from an AC supply sale, I kind of needed a large, Bertha/Max style draggy rocket to 'expend' them. The sandwich fin construction is super, quarter the weight of equivalent plywood - it's going into the do again list.

 

[Neutronium95]

Thanks for the tip on the basswood half rounds. I've been struggling to find half rounds in the size I need to edge the fins on my AMW Fibermax.

I really like how clean your build came out. I think that the Quark I built as a kid got eaten by the sky at some point.

 

[RobertH3]

We had one eaten too when I was flying with my kids. Along with Streaks, Mosquitos, etc. The small one I made is staying a display bird.

Cheers / Robert

 

[RobertH3]

Got to fly the 29mm Quark upscale at the WSR low-mid power launch yesterday in Dayton. Flew on an "Estes by Aerotech" F26-6FJ and an F50-T6. Both flights were beautiful, perfect day with very little wind. Not a trace of wobble. Blackjack motor provided a nice visible flight to app. 1000' and the Blue Thunder gave an "instant vanish" launch to app the same. Second flight did a 4-point landing. This is a good upscale for sport flying, quite happy with it. It's going to fly until it falls apart!
If there is any issue, it would be parachute pack - there is very little room above the motor mount and you have to pack a "disc" of wadding/dog barf and tuck the parachute in with a little squish by the nose cone shoulder. If you decide to build one, make the body tube a little longer than perfect scale (1/2 - 1") to give some recovery system room. I did increase the shock cord length to 8' and good thing too.

Cheers / Robert