[NRV Rocketry] Suggestions for good L2/L3 Rockets?

[bruce fette]

All,
I have been studying what it takes to make RocksimV9 line up with an actual flight.

I dont know what simulator you are using, but this may give you some insights:

Rocksim underestimated weight by 33%
Overestimated peak altitude 10% after correcting the weight (motor model is off)
Overestimated the peak velocity 20% after correcting the weight  (motor model is off)
Substantially underestimated the Cd of the main chute by 2:1, and thus predicted that the landing velocity was 50% higher than actual after correcting the weight.

This result reflects a Cesaroni 38 mm H400 VMAX on a 4" rocket body.

So anyway, Rocksim or other simulators may have various assumptions that bias actual results somewhat.

So plan for margin, re-measure and re-simulate.

Bruce



________________________________
 From: Bob Schoner <bob.schoner at gmail.com>
To: nrv rocketry <nrvr at nrvr.org> 
Sent: Sunday, July 13, 2014 8:59 PM
Subject: Re: [NRV Rocketry] Suggestions for good L2/L3 Rockets?
 


The only restrictions I have heard about were for kits with fin cans.  I don't know if this was ever explicitly banned, but the general thought is that an L3 flyer should be able to build their own motor mount/fin can unit.

Bob  



On Sat, Jul 12, 2014 at 1:55 PM, james desposito <jdesposito69 at hotmail.com> wrote:


>
>
>NO it can be a kit
>
>
>
>________________________________
>From: maier.chris at gmail.com
>Date: Sat, 12 Jul 2014 08:58:07 -0500
>To: nrvr at nrvr.org
>CC: tweeksjunk2 at theweeks.org; nrvr at nrvr.org
>Subject: Re: [NRV Rocketry] Suggestions for good L2/L3 Rockets?
>
>
>
>Go motor mount-less.  Fixing a motor mount tube in large airframes proves inflexible if you happen to attend an LDRS or big waiver type of launch.  You end up having to build another purpose but rocket instead of just swapping in a 98mm motor.
>
>
>I would recommend against any cluster that lacks a central motor capable of lifting the rocket solo for a cert flight - too much could go wrong for a cert flight, and the highest priority is safety when launching the larger L3 type rockets as well.  Air start your clusters to minimize issues and provide better distance between the rocket and spectators in case there is an issue like one of the motors doesn't light or come up to pressure at the same time as the others.
>
>
>Don't the rules still specify an L3 project has to be scratch built?
>
>
>Chris 
>
>On Jul 12, 2014, at 7:23, james desposito <jdesposito69 at hotmail.com> wrote:
>
>
>After a lot of homework and building a 5'' Big Nuke kit from Loc for my level 3 i found out it is going to hit a altitude of 
>>over 10,200 feet and not to many places to fly. know I''m thinking more toured a 7.67'' rocket like the  Bruiser-EXP - 3" from Loc that will stay under 10,000 feet with the smallest M. You have a better chance of keeping your rocket with an 8'' just my opinion. jimmy d 
>>
>>
>>> From: tweeksjunk2 at theweeks.org
>>> To: nrvr at nrvr.org
>>> Date: Sat, 12 Jul 2014 02:00:08 -0400
>>> Subject: [NRV Rocketry] Suggestions for good L2/L3 Rockets?
>>> 
>>> Hey all..
>>> 
>>> So we've had a lot of people certing up as of late. They've got their Level-1 
>>> (H-I motors)  and Level-2 certs (J-L).. and some are trying (or at least 
>>> starting to think about) their Level-3 now (M-O motors).
>>> 
>>> I'm thinking my next big rocket will probably be a 5" (dia) airframe, probably 
>>> all fiberglass or bluetube. Maybe scratch built (with a nice big ebay for lots 
>>> of electronics and HAM radio gear).. maybe a kit.  I like the flexibility of a 
>>> multi-motor cluster, like what Giovanni had on his black momba:
>>> http://nrvr.org/photos/2012-02-04-5_NRVR-VAST-VT-Launch/IMG_2421.JPG
>>> http://nrvr.org/photos/2012-02-04-5_NRVR-VAST-VT-Launch/IMG_2422.JPG
>>> http://nrvr.org/photos/2012-02-04-5_NRVR-VAST-VT-Launch/video/MVI_2435.flv.html
>>> 
>>> or maybe a just a more traditional single 75mm:
>>> http://nrvr.org/photos/2011-09-10-11_NRVR-VAST-Launch-WEB/2011-09-10-11_nrvr-
>>> vast-launch/img_1053.jpeg.html
>>> 
>>> Suggestions.. thoughts.. related questions?
>>> 
>>> Tweeks
>>> p.s. we're working out the final details for another Kentland launch in two 
>>> weeks (26th).
>>> _______________________________________________
>>> NRVR mailing list
>>> NRVR at nrvr.org
>>> http://nrvr.org/mailman/listinfo/nrvr
>>
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