Question 1

what is the internal diameter of the red threaded end of the assembly?  Is it the same as the internal diameter of the threaded 2L bottle opening?

Accepted Answer

This answer is coming from Dallas Murdoch, Owner of EZ-Launch LLC and a dealer for the red fins.  The internal portion of the top half of the red fin assembly is threaded and screws onto the launch bottle.  Its diameter is 29.6 mm.  The internal diameter of the threaded opening on a two liter launch bottle is 21.0 mm.  The internal diameter of the lower 1/2 of the fin assembly is 21.3 mm.  The internal diameter of the pop bottle where the external threads are located is 21.1 mm.  If you are using an EZ-Launch bottle rocket launcher with the red booster fins, you need to have a round white ABS plastic insert glued to the lower threaded portion of the red booster fins.  This comes with the booster fins when ordered from EZ-launch.com and is necessary to lock the bottle with the fins into the EZ-Launch bottle rocket launcher.  Also, The red booster fin assembly requires a separate black launch pipe in order for the bottle to maintain a steady air pressure and hold the water inside of the bottle.  This also is included in the EZ-Launch bottle rocket booster kit that comes from EZ-Launch LLC.

Question 2

Why do these required using an additional nose cone?

Accepted Answer

the additional nose cone improves aerodynamics and is where the parachute is placed for launch

Question 3

What type of plastic is this product made with, my son has sensitivities.

Accepted Answer

The StratoFins are made from polypropylene (PP), which is the same plastic on the white cover of a Tic Tac Mint container that has the "living hinge."

Question 4

Like the nose cone idea. Anybody use a mylar parachute?

Accepted Answer

We have no experience with using mylar for a parachute, but that sounds like an interesting idea. It should be durable and lightweight, which might make a great choice for material. The only issue might be how well it drapes, since it could be somewhat stiff although you could pre-wrinkle it. Plastic trash bag work for parachutes and mylar wouldn't be too much different from that of than draping. We use rip-stop nylon for our parachutes, which is very durable with great longevity. If you are using it on a water rocket, watch the video link if you haven't seen it already. It will help explain attaching it to a 2-liter soda bottle and offer deployment techniques.

ASIN	B00BA3K0WY
Age Range Description	14 - 99 years
Best Sellers Rank	#87,312 in Sports & Outdoors ( See Top 100 in Sports & Outdoors ) #1,719 in Water Bottle Accessories
Brand Name	Relationshipware
Color	Red
Customer Reviews	4.5 4.5 out of 5 stars (542)
Educational Objective	STEM
Indoor Outdoor Usage	Outdoor
Item Dimensions	7.5 x 5.12 x 1.75 inches
Item Weight	1 ounces
Manufacturer	Relationshipware
Manufacturer Part Number	FIN-1
Manufacturer recommended age	14 years and up
Material Type	Plastic
Model Number	FIN-1
Number of Packs	1
Number of Players	1
Operation Mode	Manual
Set Name	1
Size	Medium
Theme	Rocket
UPC	700220318885

StratoFins Screw-on Water Rocket Fins - Compatible with 2 Liter Bottles or Smaller

Description

Specifications

Common Questions