Eyelash: an altitude seeking minimum diameter I class scratch build

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
I made two changes to eyelash prior to launching it again.

I added an internal bulkhead connection as a firm connection for the backup tether in case the bolts of the electronics bay pulled out. This is the tab with the hole and arch just behind the lower screw mount in the photo below.

IMG_8695crop.JPG

I also trimmed down the fins so that the rocket is not quite as overstable.

trim lines.jpg

Even after trimming to reduce drag, the rocket left the pad with 3.3 calibers of stability. I did minimal trimming because the rocket was predicted to go about Mach 1.6. I don't have a lot of experience with supersonic flight with a fin height less than one body diameter. The trimmed fins have a span of just 33 mm, which is 0.81 of the 41 mm body outer diameter. I now know this can result in stable flight with a large stability margin.

Here is eyelash (right) with trimmed toenails along with new sibling that I call Effed Up.

IMG_8878crop.JPG
 
Flight #4 of eyelash went up 15656 feet.

statistics.png

While this is just 141 feet higher than flight #3, I did not add the extra 56 grams nose weight to this flight so it was probably underweight. The extra weight appeared to add a few hundred feet to flight #3. I have all winter to figure out what may provide eyelash with additional levity.

View attachment eyelash 4 in 720.mp4
















Upper level winds were a little higher than previous flights. The rocket came down 4.1 statute miles away, just inside our flight cylinder of 4.0 nautical miles = 4.7 statute miles. GPS is amazing.

google3dWithMiles.PNG IMG_8863.JPG
 
Back
Top