Flutter-By + cord...bad idea?

Hey folks,

I purchased several Flutter-By kits, and put together two of them. One of them, I used about a 20" length of kite string to tie together in hopes the pieces stay close together after the ejection charge. It's tied around the engine tube...trying to avoid the "zipper" thing people talk about.
Is this a good idea? I don't have any kevlar cord (although I have some olllllld kevlar thread from craft projects over 15 years ago, been stored all that time)
Any suggestions for shock-cording the remaining 4 Flutter-bys as my son and I build them?

I have built and flown quite a few of these...to include my BT-80 upscale, the Fatter-By. I haven't ever tied them together and the two pieces have always been close enough together to not be a problem. The only time that I have not recovered both pieces was when we shot one up on a B6 and the whole rocket disappeared.

The Fatter-By does catch a bit more wind but the pieces are a bit larger and easier to track.

Give it a shot and see how it works out. I contemplated doing this with my upscale but decided against it because I am hard headed. Maybe you could add a centering ring at the end of the MMT to create a protected space for the tether. Depending on where you want to connect it to the nose section, you could slot the existing collar to clear the tether when it is all put together.

Since the Flutter-By is supposed to be a "Maple Seed" Helicopter recovery model with both pieces rotating down tying them together will like completely stop any rotation causing the model to come down much faster then designed.
My thought is it well likely snap the single fin on the upper section on landing if not both. Way before that however your 20 inches of shock cord will be snapped when the ejection charge pops the pieces apart. 20" of anything is WAY to shot for this size model. You might get away with 36 or 42" Which should give the parts time to slow down before hitting the end of the string. Perhaps tied together they Might rotate around each other but I truly doubt it.

I still have an original Flutter-by from back in the day and a few years back made T4 (.448" diameter) 2.6x Downscale size Micro powered version. Never had any problem recovering both pieces of either model flying on normal breezy days.
I did paint the micro version in fluorescent & Silver colors just to make it a bit easier to find the pieces on the ground.

I was mostly concerned about the "lawn darting" that people have mentioned several times about this model.

I have never had one of these lawn dart and a F-B is on the schedule pretty much every time my son and I launch (not only is it our favorite but it makes for a good weather bird). We have about 30 launches on these and have only popped one fin, never lawn darted and have waved bye-bye to three of them.

John brings up a good point about tethering that I hadn't considered. It would take quite a long cord to absorb enough of the shock to keep the force from the charge from tearing the sections up.

Due to recovery concerns, I built my upscale with a slight cant (about 2°) to the fins of the nose section. It boosts fairly straight and the nose does a somewhat flat spiral to the ground and drifts much less than the booster. I am going to try this on my next 18mm F-B and see how it works out.

John, I like your micro idea! Like I said before, this is a favorite at our house so a micro would fit in beautifully! It would also be great for our Cub Scout launch in the spring. Couldnyou imagine launching a micro, an 18mm and 24mm simultaneously? I think I would want a decent sized field for that.

Cording the two pieces in any case sort of violates the whole point of the rocket.
Keys to recovery:
Don't go bigger than an A8-3 engine. There is no point, it will go out of sight and be hard to find the pieces. Pretty much the initial lift off and the fluttering recovery are the key points of the flight, so additional altitude is NOT your friend.
Have at least two spotters, and try to make sure you are not BOTH tracking the same part down to the ground
Since there is no chute or streamer, all you are going to find on the ground is the upper or lower part of the rockets. It's not very big. Recommend launch on a very flat field (well mowed athletic field is perfect. Pavement is an alternative, but kind of rough on the rocket as pieces come in kind of hard, easy to pop a fin or chip your paint.)
Paint it bright colors, if you stick with stock scheme use bright silver paint and a popping red for the fins. Contrasting Fluorescents would be MUCH better if you aren't a purist.

Don't fly it naked, balsa colored, in fall, with brown balsa colored leaves on the ground. Don't ask me how I know this.

Have fun, it's a neat rocket!

I think these paint jobs might be bright enough. The blue and gold one is the one with the kite string, and it's about 2' of it stuffed up in there. https://www.flickr.com/photos/mikhailolegovich/21788257150/in/dateposted-public/

I launched mine 2 weeks ago and both pieces sadly fluttered bye bye on the initial launch. The one piece just kept going and going and going (they were both lost to the ocean). I thought I would be OK with a B engine, but I was wrong. It was a windy day, but holy cow, the one piece really just kept on drifting sideways forever before I lost sight of it.

The .5 rocket I lost out of my 100+ flights was the lower half of a Flutter-By on a B6-4.

Of note is that I believe the FB design/build had changed slightly from original to present...I think Estes added/added more clay to the nose to address some possible earlier model issues. This may be a cause for more lawn darts since the nose is now heavier...like a dart! I've had it happen on mine, but it's no big deal in a FB since it's a free-fall recovery anyway.

Just finished my "minimum effort" Flutter-By. Built it in one sitting with medium CA, painted it the next day, and the decal the next morning. No wood grain filling and no clear coat. My back yard pastures have taller grass so I won't be flying this one in the back yard.

SirNomad said:

I think these paint jobs might be bright enough. The blue and gold one is the one with the kite string, and it's about 2' of it stuffed up in there.

https://www.flickr.com/photos/mikhailolegovich/21788257150/in/dateposted-public/

Click to expand...

Just remember 24" of kite string is NOT enough to allow the parts to slow down before hitting the end of the string hard. More then likely damaging one or both parts if nothing else it Will Snap the string sending your parts down separately anyway. Teathering this kind of recovery model is just NOT a good idea.

So I decided to go for it in the pasture and flew it on an A8-3. Altitude was about what I expected but wow, the separation was a lot more violent than I expected. Blew the pieces farther apart than I expected. Recovered both pieces no problem but I'm glad I had my wife spotting for me. Fun little bird and it's kind of nice having no recovery system to prep before flying it.