Payload ALTITUDE Clarification

[Sandy H.]

**Edit** Title should be Payload Altitude, not duration. My mistake. ****

I have been reading the pinkbook and think I've misinterpreted something about this class. I have been thinking that the contest director supplied the payload and people 'check them out' and fly them. The more I look at it, though, I think the flier can build his/her own payload (of the proper outside dimensions) of any weight (over 28 grams), present it prior to the flight and return it for inspection after the flight. Is that correct?

I am making a few payloads that meet this requirement to give out if people want them, but I don't think they would be required to use them.

For reference, this is my first stint as a contest director, so any help is appreciated. The contest isn't actually sanctioned, but we're doing it to work the bugs out, so I want to stick to the rules!

Thanks!

Sandy.

 

[Bazookadale]

I have been to contests where the director supplied all the payloads and REQUIRED the contestant to use the supplied payload. I have also been to contests where none were provided and the contestant MUST provide their own. Most contests however do both - supply payloads to those who need them but also allow contestant supplied, and this is the best way to do it. You must be prepared to measure and weigh payloads on site.

Payload duration? Has this just been approved, in the past Payload was strictly altitude

PS tell the contestants the length of your payloads beforehand as there is a +/- 10mm range

 

[Sandy H.]

YIKES!!! Sorry, it is payload altitude, not duration. I was clarifying various rules and one of those was for a duration event.

This question was about payload altitude. Sorry for the confusion.

Thanks for the information. I will go ahead and bring payloads but allow for others to use their own if they meet the specs. I will have a scale as well, so all should be good.

I appreciate the help!

Sandy.

 

[Micromeister]

Sandy:
it's almost always an either or with people having the option of providing their own payload as long as it meets the specifications for diameter, length and mass not exceeding 28grams.

For Naram-50 I made up a couple guages for use at check-in to help speed up the measurements. Mass readings had to be done on Offical NAR certified scale.

That is I believe the biggest headache about bringing your own. If your home scale isn't all that accurate you may end up using a loaner payload on the field.

View attachment NAR Payload Measure-c_01-29-08.pdf

 

[JStarStar]

Just to clear up my own confusion, the exterior diameter corresponds to BT-20 (i.e., it won't fit INSIDE a BT-20) ?

So, gluing a used motor casing inside a BT-20 70mm motor mount tube, sealing the nozzle end with epoxy (or gluing a paper cap over it), filling with sand to a weight of 28g, and sealing the open end with a paper cap glued over the end (you'd have to pre-adjust the sand amount to account for the weight of the cap) would give you a usable NAR Standard Payload?

If I didn't want to go to the trouble, does anybody sell them?

I just did a quick search of the usual suspects and I can't find any.

 

[Sandy H.]

To clarify, the minimum mass is 28g, not the maximum.

J**: I think your plan is basically fine, if you were shooting for exactly 28g. If you didn't mind going a bit over, then you could probably skip the step of tweaking prior to final sealing.

My intent is to cut BT-20 tubes to the nominal 70mm, put a thin ply bulkhead cap in one end, fill with sand to a total weight of 28 grams and then cap with a bulkhead and glue. Our club is small, but I'm planning on making 4 to share. I doubt there will be 4 contestants, but if there are more, we'll fly in rotation.

Micro: Awesome idea about the check gage. May I copy it?

Also, I assume that the scale had to be NAR certified due to it being such a big event. For a regular local event, is using a typical digital gram scale (.1 resolution) with its standard calibration weight acceptable?

Again, our event isn't sanctioned this go-round as we're trying to figure out all of the ins and outs, but we might as well do everything by the book as far as I'm concerned.

Thanks for the additional insight.

Sandy.

 

[Micromeister]

To clarify, the minimum mass is 28g, not the maximum.

J**: I think your plan is basically fine, if you were shooting for exactly 28g. If you didn't mind going a bit over, then you could probably skip the step of tweaking prior to final sealing.

My intent is to cut BT-20 tubes to the nominal 70mm, put a thin ply bulkhead cap in one end, fill with sand to a total weight of 28 grams and then cap with a bulkhead and glue. Our club is small, but I'm planning on making 4 to share. I doubt there will be 4 contestants, but if there are more, we'll fly in rotation.

Micro: Awesome idea about the check gage. May I copy it?

Also, I assume that the scale had to be NAR certified due to it being such a big event. For a regular local event, is using a typical digital gram scale (.1 resolution) with its standard calibration weight acceptable?

Again, our event isn't sanctioned this go-round as we're trying to figure out all of the ins and outs, but we might as well do everything by the book as far as I'm concerned.

Thanks for the additional insight.

Sandy.

Sure Sandy: just be sure to use the proper OD for your guage.

Jstarstar is exactly correct 18mm payloads do not fit in a BT-20 body tube.. But they do Fit very well in 19mm standard .013" wall telescope tubing. Which is how most build their Payload models. BT-20 (18mm) motor tubing sleeved into 19mm Payload housing forward section. With some sort of Paylaod extraction method. Most glue the Nosecones on permanently.

 

[mge55389]

Aerospace Speciality Products also sells NAR payload kits that you assemble:

https://www.asp-rocketry.com/store//moreinfo.cfm?Product_ID=547&Category=176

Good luck with your contest!