Will the tripod melt?

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RobN

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With the Blast Deflector resting right on the tripod, which is plastic, wouldn't the tripod melt?

adeptor_assembly.jpg

Thanks, Rob.
 
No. The thermal plume is typically so brief that the plastic never gets near its transition temperature. Especially so if you use a good standoff distance from the plate.

As an alternative to the plate material you can get ceramic square tiles at the big box home improvement stores. Ceramics can take a heavy thermal soak. But it's just an option. In many cases you'll be fine with the plate.

All bets are off if the lug hangs on the rod though. The flame jet can be like a cutting torch if it is too close to the plate.

Greg
 
With the Blast Deflector resting right on the tripod, which is plastic, wouldn't the tripod melt?

View attachment 275663

Thanks, Rob.


Rob:
For all but the most severe mishaps as Glen sighted, your deflector plate sitting directly on the Tripod plastic pad won't even get warm on most flights.
It does look like your using a fairly thin gauge steel deflector. Over the years I've found that 16ga. 304 stainless Steel deflectors can handle even hung up G motors without burning through. Bends the heck out of them but not a single penetration;) On most of my personal pads and tripod launchers I use a 4" square 16ga. 304 or 316 Stainless steel deflector plate. I generally get my Stainless On-line is 12" or 24" square sheets. Stainless steel is very dense TOUGH material. You'll need either are cut-off grinder or bi-metal HS 32tooth band saw to cut it. Drilling the holes is done with standard HSS drill bits but is done in steps 1/8", 3/16, 1/4" etc.

Another option would be to add a second Stainless Steel 3" OD 12ga. 304 Stainless fender washer under your larger diameter top plate. This combination would ensure you'd never have a problem with deflector burn through. McMaster-Carr sell these larger diameter fender washers in 5 packs #90313A309 last time I purchased a pack they were 1.71ea or 8.55 for the pack . Actually pretty cheap insurance. and yes for most model rocket use 3" diameter is plenty as a primary deflector.
 

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  • TripodLaunchRodAdaptor-b3_.1875inStStlRod&Deflector on Tripod_5-19-01.jpg
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  • Blast Deflectors-h_.25in x 3.0in x 12ga St Stl Fender Washers - McMaster#90313A309 (1.71ea)_06-0.jpg
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  • Blast Deflectors-i_16ga 304 Stainless 6in Sq.Deflector Curv_08-03-13.JPG
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  • 691Lp01a_MM MakerBeam Test-c1_Silver Streak (A10-3T) Test on Rail_04-19-14.jpg
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Thanks guys for putting my mind at ease. That picture is actually not mine. I borrowed it just to ask the question.

Here is my setup:

20151105_105934.jpg

I originally was putting the deflector on top of the coupling nut, but it wobbled too much. The plate I am using is cut from a door kick plate I found in my garage. It is the same thickness as the Estes Deflector plate. No idea on what the steel is. Should I be concerned using that??

Thanks, Rob.
 
an old saw blade works also
10opfee.jpg
 
Our club uses abrasive metal cutting blades or grinding discs as blast deflectors over the tops of our steel ones mainly on HPR and MPR pads.
 
No. The thermal plume is typically so brief that the plastic never gets near its transition temperature. Especially so if you use a good standoff distance from the plate.

If possible, I would strongly recommend that you remove the tripod head and utilize the mounting screw that might be hiding beneath. Better tripods are configured to allow the use of different heads, and use either 1/4"-20 (good) or 3/8"-16 (better) threads for this purpose. There's an article on the subject to be found on the NAR website at:

https://www.nar.org/contest-flying/fai-spacemodeling/construction-techniques/tower-launchers/

Hope this helps,
James
 
Keep some modeling clay handy in order to fill up any gaps in the system- typically the inside of the short tube that goes through the actual blast deflector. That way you can eliminate any of the pathways that the motor blast may want to go through. The biggest issue would be oxidation eventually messing up your tripod.
 
If possible, I would strongly recommend that you remove the tripod head and utilize the mounting screw that might be hiding beneath. Better tripods are configured to allow the use of different heads, and use either 1/4"-20 (good) or 3/8"-16 (better) threads for this purpose. There's an article on the subject to be found on the NAR website at:

https://www.nar.org/contest-flying/fai-spacemodeling/construction-techniques/tower-launchers/

Hope this helps,
James

If it is a good tripod I would not use it for launching rockets with or without the head.
 
If it is a good tripod I would not use it for launching rockets with or without the head.

There is no danger to the tripod using the procedures outlined in the article found on the NAR website. If one is concerned about the possibility of damage to an expensive tripod or simply does not want to invest that much money, there are suggestions for using an inexpensive microphone stand in the article. After using the mic stand setup for almost a year I am convinced that it is superior to a photo tripod, anyway.

James
 
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