Old Design -- Solo's Nail

[CPMcGraw]

From 2007.

This design was not posted to the official list, because there were some questions about the flight profile. But I believe the original model has flown (Solomoriah, can you elaborate here?), so the simulations shown in the RKT file should not be taken as unfounded. The design presented here uses a simulated skirt to force the airflow around the rings in the manner it does in the wild.

Length: 14.84"
Diameter: 0.736" (BT-20)
Fin Span: 1.90"
Weight: 0.83 oz


A10-3T......368'......Dv 20 FPS
A3-4T.......383'......Dv 8 FPS


Launch rod: 36" x 1/8"

[barone]

From 2007.

This design was not posted to the official list, because there were some questions about the flight profile. But I believe the original model has flown (Solomoriah, can you elaborate here?), so the simulations shown in the RKT file should not be taken as unfounded. The design presented here uses a simulated skirt to force the airflow around the rings in the manner it does in the wild.

Length: 14.84"
Diameter: 0.736" (BT-20)
Fin Span: 1.90"
Weight: 0.83 oz


A10-3T......368'......Dv 20 FPS
A3-4T.......383'......Dv 8 FPS


Launch rod: 36" x 1/8"
I flew mine...it had a bit of a stability issue..... :o

[CPMcGraw]

I flew mine...it had a bit of a stability issue..... :o

Were you able to correct the instability? I understand what the rings are supposed to do, work like a conical skirt, with each ring pushing a little of the air outward at a time.

[DaveR]

I flew mine...it had a bit of a stability issue..... :o
A "bit" of a stability issue??? :eek: That's a "bit" of an understatement don't ya think? Of course the wind might have had a "bit" to do with it.
Didn't it hit the ground under power?

[CPMcGraw]

A "bit" of a stability issue??? :eek: That's a "bit" of an understatement don't ya think? Of course the wind might have had a "bit" to do with it.
Didn't it hit the ground under power?

I take it you "observed" the alleged flight? :D

Can you describe the observed path of the Nail?

[Solomoriah]

I never got mine tested... it failed in build. Or more to the point, I failed building it. I was considering another crack at it this winter but haven't gotten around to it.

I may make a whole line of test models to scope out the variables.

[johnnwwa]

I built the one that was posted on TRF Bt50 w/5055, 5060,5070, 5080 Centering rings added 1/2oz.-1 oz. clay to NC not sure how much. Flight was a headsup flight :eek: at about 80 feet this rocket went unstable and did two complete loops,chute deployed at about 60 feet no damage cool to watch but I thought that by adding nose weight that would have cured the problem.
Thinking about adding some clear plastic fins. More testing needed.

BAR
John

[DaveR]

I take it you "observed" the alleged flight? :D

Can you describe the observed path of the Nail?
First let me say it was extremely windy that day. From what I remember, I'd say the NAIL made it to maybe 30 or 40' before becoming unstable. Then it was the usual unstable erratic behavior, a couple of semi-loops while shooting back and forth. As I said, I think it hit the ground under power about 50 feet or so from the pad. It was definately on the ground when the ejection charge fired. In all fairness to this design; it may well fly better on a clam day.

I'm sure Don can offer more insight, he has the mind of an elephant you know. :D

[rstaff3]

I understand (I think) the idea behind the rings, but it didn't surprise me it wasn't stable. Unless sized and spaced properly, I could see that the upper ones might even interfere with the airflow around the others. Plus it seems without a conical shroud there is no protection at all against lateral disturbances.

It seems the largest ring should be a lot larger than it is. It would be interesting to see someone make a series of models with the largest diameter ring successively larger and see if that would stabilize it. In some limiting size it should act like a 'half-spool rocket', which has been proven to be stable.

[barone]

.......I'm sure Don can offer more insight, he has the mind of an elephant you know. :D
There you go ......alluding to my size.....lol

If I remember correctly, and it has been nearly a year, it was just the tracking smoke burning when it landed. A couple of loops under power and then just kinda dropping to the ground. It was windy though, but I don't think that mattered much. I launched my Custom Rockets Serval (tube fin design) that same day and it went straight up....as in no weather cocking....however, it did significantly tack as it went "straight up". :rolleyes: