Wadding

[brockrwood]

Slightly off topic, but I used to have a homemade streamer (fairly small) that had a penny taped to one end to weight it. The “penny streamer” was placed in the model rocket tube, rocket got launched, and penny streamer got ejected. We then timed how long it took for the penny streamer to hit the ground. The speed at which it was falling times the amount of time to hit the ground = rough altitude at ejection. If time of ejection was close to time of apogee, then we could get a rough idea of how high the rocket went. The only reason for the streamer was so you could see it. The penny by itself would be a better object to use.
What I can’t remember is the speed we used for the rate at which the penny streamer fell. I think we assumed that it accelerated to “terminal velocity” fairly quickly, so we ignored the acceleration phase? I can’t remember.

I googled it. Bill Stine came up with this idea in 1974. He calls it “Standard Altitude Marker”. I must have read about it somewhere. Anyway, a 3 gram weight on a plastic streamer 12 inches by 1 inch and .0001 thick should fall at about 18 feet per second (I guess Bill blew off the acceleration phase too).
http://www.hobbizine.com/rocketaltitude.html

 

[brockrwood]

I googled it. Bill Stine came up with this idea in 1974. He calls it “Standard Altitude Marker”. I must have read about it somewhere. Anyway, a 3 gram weight on a plastic streamer 12 inches by 1 inch and .0001 thick should fall at about 18 feet per second (I guess Bill blew off the acceleration phase too).
http://www.hobbizine.com/rocketaltitude.html

So, if the penny streamer’s terminal velocity is 18 feet per second and Earth’s gravity accelerates objects at 32 feet per second per second, then the penny streamer hits terminal velocity within the first second.
Terminal velocity of 18 feet per second? That sounds slow.
Ah! Found it. This stuff is in the handbook of model rocketry.
So the streamer is more than a visual tracking device. It slows down the descent of the penny. A lot.

 

[BABAR]

Last January, Bill Stine said Estes purchases more TP than anyone in the county other than the county prison.

I would have guessed Congress…….

 

[DaHabes]

If the rocket is BT-50 to BT-80 and the airframe is long enough, I put in a baffle. No wadding, no nomex blanket. I even built a custom one for my vintage 4" NCR Patriot that I had to rebuild. I use wadding only for BT-5 rockets (because you can get by with one sheet) and dog barf for BT-20 (because it requires more than one sheet but is too small for a nomex blanket).

 

[brockrwood]

If the rocket is BT-50 to BT-80 and the airframe is long enough, I put in a baffle. No wadding, no nomex blanket. I even built a custom one for my vintage 4" NCR Patriot that I had to rebuild. I use wadding only for BT-5 rockets (because you can get by with one sheet) and dog barf for BT-20 (because it requires more than one sheet but is too small for a nomex blanket).

So, BT-50 and up you are a baffle guy? How do you get it in there. Do you use it as a tube coupler?

 

[DaHabes]

I've built my own with tube couplers, there are a couple of designs you can dredge up on TRF. But for ease of build, I have an inventory of Qualman baffles. They are very reasonably priced (actually, downright cheap) and easy to incorporate into any build as long as the airframe is long enough for the baffle and the laundry to co-exist.

http://www.qualmanrocketry.com/Baffle BT plywood.html

 

[Ronz Rocketz]

The Qualmans are easy to insert as long as there isn’t anything significant blocking or you remember to attach the Kevlar to the eyelet. It’s possible to attach the string to the MM and pass around the baffle. If the Kevlar breaks before the baffle, the glue might hold the string. I think it’s easier to use the eyelet.