Another A8-5 Altitude Record?

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ogivemeahome
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Another A8-5 Altitude Record?

Postby ogivemeahome » Wed Mar 21, 2012 10:55 pm

Hey all. My last little rocket was poorly designed in terms of longevity so here is the next design.

See previous rocket at this thread:http://www.ausrocketry.com/forum/viewtopic.php?f=10&t=3497
See records listings here:http://www.mts.net/~rns/URR/All-time%20Altitude%20records.htm

The 'warty' bit on the fin tip chord (see below) was the only way I could figure out how to simulate a 'T' fin in OpenRocket. (The sim has the same surface area as the finished article.) The 'T' is two circular segments back to back (picture a tiny surfboard on top of each fin). This moves the Cp aft negating the need for nose weight to provide stability. Flutter may be an issue - the root fillets will be generous. Initial sim beats the previous record of 433' by a comfortable margin.
Summary: A8-5, 'Altimeter One' (If it still works? - may have to get a new one), streamer recovery.
Pics when I make some progress.
Attachments
FF_InitialSim.JPG
I have a couple of names in mind. That'll depend on how the paint job turns out.
FF_InitialSim.JPG (50.9 KiB) Viewed 2466 times
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Re: Another A8-5 Altitude Record?

Postby kopius » Thu Mar 22, 2012 11:59 pm

ogivemeahome wrote:'Altimeter One' (If it still works? - may have to get a new one)


I heard there is a really good place to get these if you need them, I will find out and let you know ;-)
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ogivemeahome
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Re: Another A8-5 Altitude Record?

Postby ogivemeahome » Fri Mar 30, 2012 9:15 pm

ogivemeahome wrote:...the root fillets will be generous.

Oops, my grammar is slipping. The root fillets will be generously proportioned.
The paint didn't quite turn out as planned but it'll do. Stll to do:
- attach kevlar cord to inside of Body Tube
- fit launch lug
- break a record 8)
Not sure when the attempt will be - cool air is more dense (probably not an issue for this one).
Attachments
LL_FF_A1_edit.jpg
Here comes the Frisky Frog.
LL_FF_A1_edit.jpg (79.37 KiB) Viewed 2410 times
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Re: Another A8-5 Altitude Record?

Postby krusty » Mon Apr 16, 2012 1:16 pm

ogivemeahome wrote:Hey all. My last little rocket was poorly designed in terms of longevity so here is the next design.


Have you thought about having your fins laser cut?

Having perfectly matched fins may help with your altitude attempts.

If you're interested, let me know. I can take templates from RockSim (Export fin template) or in CDR (CorelDRAW) DXF, PDF and most SVG formats. (Inkscape, for whatever reason, doesn't produce a compatable SVG file!)

Krusty

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Re: Another A8-5 Altitude Record?

Postby ogivemeahome » Mon Apr 16, 2012 11:06 pm

krusty wrote:Have you thought about having your fins laser cut? ... Having perfectly matched fins may help with your altitude attempts.

Yes, that would save me some time. I match them by cutting slightly oversize, drilling two holes through all three fins and pinning them together. Once pinned, they get the treatment - planing and sanding. The T's on this one were too fiddly to hang on to so there is a slight mismatch (and a slight misalignment). It should still fly straight enough though.
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Re: Another A8-5 Altitude Record?

Postby ogivemeahome » Mon Apr 23, 2012 4:44 pm

Ready to fly as soon as there is some favourable weather (and a club launch day). Who'd a thunk you could exceed 400' with an A8-5?
Attachments
FF_WeighIn.jpg
The rocket (with altimeter) weighs as much as the motor. All up weight is 33 grams including motor.
FF_WeighIn.jpg (86.37 KiB) Viewed 2344 times
FF_FinalSim.JPG
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Re: Another A8-5 Altitude Record?

Postby ogivemeahome » Tue May 22, 2012 10:42 pm

The story so far...
My Altimeter One had the cover knocked off it on its third flight (impacted a fin during deployment). So, I made a replacement cover out of balsa reinforced with CA and epoxied it on (it still weighs about the same). As far as I know it's been working fine until the Leaping Lizard's 2nd flight which came in ballistic. The next few rocket flights with the same altimeter gave odd readings until it seemed to work fine again.
On Sunday 20/05, I flew it in a rocket which I knew would go to around 1200' (the reading was 1209').
A fellow club member kindly loaned me his Altimeter One so I could fly it in the same rocket (that flight gave 1181')
Next flight was the Frisky Frog with an A8-5. The reading was 534'.

Given that I simmed the Frisky Frog to around 500' and that sims are usually generous with their predictions, how did it get to 534'?
1. Compare the sim with the picture - the sim was meant to allow for the 'T' fins. Does this cause inaccuracy?
2. Is the altimeter still accurate given its history?
3. Is it possible that the rocket caught a thermal/updraft?
I'm reluctant to claim a record just yet. I think I'll fly it a few more times and compare flights.
Anyway, here's some pics:
Attachments
1_SpotTheFrog.jpg
A straight flight, touch down about 50m (?) from the pad. The streamer didn't unfurl.
1_SpotTheFrog.jpg (180.05 KiB) Viewed 2307 times
2_NiceAltShAbTheFin.jpg
Nice altitude, shame about the fin.
2_NiceAltShAbTheFin.jpg (89.24 KiB) Viewed 2307 times
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Re: Another A8-5 Altitude Record?

Postby ogivemeahome » Thu Jun 28, 2012 7:50 am

ogivemeahome wrote:Given that I simmed the Frisky Frog to around 500' and that sims are usually generous with their predictions, how did it get to 534'?

Yeah, ok. If I use the right settings in OpenRocket (location, conditions) and set the paint finish to 'polished' it sims to over 540'. I'll stop beating about the bush and submit a claim.
The fin has been repaired so it's ready for another flight. This time I will open the streamer (plastic) and leave it in the sun for a few minutes, then let it cool before folding it. Oh, and it now has a longer shock cord. Hopefully, no more cracked fins.
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Re: Another A8-5 Altitude Record?

Postby Lamp » Thu Jun 28, 2012 10:19 am

I have found Rocksim to be somewhat optimistic about its altitude prediction, however Open Rocket seems to be better and if anything sims a little lower than what is actually achieved....this is my conclusion after looking at predictions from both programs and comparing them to altimeter data. This is true for my Wildman Jr and 2" Darkstar flying with H, I and J motors anyway.

I would have no problem that your sim was lower than the actual measured altitude from my experience with Open Rocket, I might hhave some reservations if you had simmed it in Rocksim.

Congratulations on the flight! :D
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ogivemeahome
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Re: Another A8-5 Altitude Record?

Postby ogivemeahome » Thu Jun 28, 2012 9:49 pm

Lamp wrote:I would have no problem that your sim was lower than the actual measured altitude from my experience with Open Rocket...

Congratulations on the flight! :D

Theory is great but there's nothing like the benefit of experience to boost the confidence! Thanks.
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Re: Another A8-5 Altitude Record?

Postby ogivemeahome » Sun Aug 19, 2012 8:50 pm

The Frisky Frog flies again - this time to 505' in similar conditions to the last launch (534'). I had to coat the damaged fin with some epoxy to strengthen it a little - this would have added negligible weight (maybe I should weigh it?!).
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Re: Another A8-5 Altitude Record?

Postby ogivemeahome » Sun Sep 09, 2012 3:05 pm

The Frisky Frog does it again! At the QRS club launch today, it flew to 550' on an A8-5. I wasn't expecting a record so didn't take the camera - Jeff has the photos.

A great big thanks to William who found the rocket - well done young man!
A smooth sea never made a skilled mariner. (English Proverb)

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Re: Another A8-5 Altitude Record?

Postby ogivemeahome » Mon Sep 10, 2012 10:55 pm

Here's the pic - Thanks Jeff!
Attachments
FF_120909_2b.jpg
The same fin keeps cracking?! Surely 550' is as good as it gets?
FF_120909_2b.jpg (72 KiB) Viewed 2041 times
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Re: Another A8-5 Altitude Record?

Postby air.command » Mon Sep 10, 2012 11:34 pm

Congrats on the great flight! 550' is an impressive altitude on that motor ... now you just need to remove that launch lug and build a tower for it. :D
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Re: Another A8-5 Altitude Record?

Postby krusty » Tue Sep 11, 2012 11:49 am

ogivemeahome wrote:The Frisky Frog does it again! At the QRS club launch today, it flew to 550' on an A8-5. I wasn't expecting a record so didn't take the camera - Jeff has the photos.

A great big thanks to William who found the rocket - well done young man!


Excellent work!

I really like the paint job! How do you get it like that ??

Krusty


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