Egglofter question for you competitors...
 

I'm working on some models for this year's NRC, and while there are a lot of plans for C Eggloft altitude, none of them specify how to accommodate an altimeter. The Apogee vacufom capsule has too short a shoulder, so I can see doing a) replace the shoulder with an appropriate length of coupler with a bulkhead for use as an altimeter bay, or b) hang the altimeter off the shock cord (not my preferred option).

Just thought I'd ask the experienced competition folks on the forum what you do...

Chris, I noticed that your blog is currently featuring an egglofter build based on the Robin - what mod did you make?

Thanks in advance!

(Note: I would also make this post on contestrockets.org, but find myself unable to post even though I am a member.)

Bill,

You can talk about egglofters on

https://groups.io/g/contestRoc

You will be able to post and get a response there.

Rule 20.2 covers altimeter rules for NAR competition. http://www.nar.org/wp-content/uploa...6/USMRSC-V3.pdf It says that "The altimeter must be fully enclosed within the rocket body through apogee. " I attach the altimeter to the capsule on the same loop that the recovery system is attached. Deployment is after apogee.

I just posted my NARAM egglofter here: https://www.thingiverse.com/thing:3056609

Congrats on your NARAM 2nd place with your printed egglofter.
I think they should bring back F Eggloft for designs like the Enerjet Egg Crate.

F Eggloft hasn't gone away.

Use a smaller altimeter like the Firefly (I love the P-Nut but its too bulky and a bit heavy compared to others). Put it into the lower half of the egg capsule, then padding, then egg.

Have small vent holes in the lower half of the capsule.

That's what I do.

Also, avoid the Micropeak. It's junk, too unreliable.

George,

I have to disagree with you about the Micropeak. Emma and I have used them with great success. And we usually just tie them to the shock cord. If you've been having problems with yours send it (them) back to Altus Metrum and have them reprogrammed.

Steve

Agreed. I have never experienced a problem with the Micropeak.

Micropeaks have issues with sunlght that require fixes no other altimeters require.

We had a GREAT C Payload flight at NARAM last year. Probably a winning altitude.

The Micropeak reported a ridiculously low altitude which seemed to be the same reading as a flight of a lower power model ( B Superroc test flight 2 weeks before), as though it did not detect liftoff on the C Payload flight (yes it had vent holes). Check-in procedure did not require writing down the previous altitude, so we had no proof, no recourse, no reflight (Flight #1 had DQ'ed and lost the first Micropeak). Last time I ever used one.

If I ever fly one again I will prepare by first pulling a high vacuum to exceed the record for the event before check-in, since if they won't record the last flight reading on the card at check-in and we got screwed again by a no-detect that kept the last flight readout, then we WOULD have a recourse (let us set aside that score and re-fly or we go with the "legally reported as per procedure" altitude score).

I totally stand by my recommendation to other fliers to avoid the Micropeak. It's untrustworthy finicky junk. Should not have to play games like that. If the software's bad, the Contest Board should issue a recall of the altimeter's certification.

Biggest mistake about the whole NAR contest altimeter stuff was NOT going with a standard type like TARC does. TARC teams are not having these headaches with a slew of altitmers, some of which can't be trusted or require the purchase of a new-enough Windows Laptop computer to use. I have Two Adrels that I can't read with any computer I own (nor my Teammate Chan who at least has a Windows-based laptop), and a third Adrel from 2017 that can't be read by anything in 2018 (I'll be returning that one. I do not care if it's an issue of 2017 software for 2017 Adrel and 2018 software for 2018 Adrel, too much hassle for two totally different sets of software (if that is the issue) for the same certified altimeter when I can't even run any of it on my computers).

We got burned on a great C ELA flight as well with a MP. Reported 45 meters. We shelved them for the rest of the week and used our FireFly.

We did the same thing as astronwolf. Tied it to the capsule and recovery system. A Firefly fits fine in a BT-20.