Ye Olde Rocket Forum

Go Back   Ye Olde Rocket Forum > Work Bench > RockSim Asylum
User Name
Password
Auctions Register FAQ Members List Calendar Today's Posts Search Mark Forums Read


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 06-19-2009, 04:13 AM
garmtn's Avatar
garmtn garmtn is offline
Craftsman
 
Join Date: Sep 2007
Location: Great Meadows, NJ
Posts: 188
Default Rocket heavier than motor rating

Just curious on opinions. I have a dual egglofter, using a Bt80 and a aertotech D21-4 motor. Carried a lighter rocket, by 4 ozs., to an altitude of 300 ft, free fell 10 seconds. I have a "fast " deploying chute of 36." Someone else got a successful recovery with a D12-3 @approx "rated lift wt." Opinions of D21-4 lifting 4oz over lift weight successfully?
Reply With Quote
  #2  
Old 06-19-2009, 08:46 AM
ghrocketman's Avatar
ghrocketman ghrocketman is offline
President, MAYHEM AGITATORS, Inc.
 
Join Date: Jul 2005
Location: Michigan
Posts: 10,389
Default

You need either MORE motor, or a LIGHTER rocket. I would not try it.
__________________
When in doubt, WHACK the GAS and DITCH the brake !!!
No DIRECT and MEASURABLE Harm=NO Foul advocate

If you are NOT FLYING LOW in the left lane, you need to GET THE #$&@ OUT of it !

Yes, there is such a thing as NORMAL
, if you have to ask, you probably aren't
!
Reply With Quote
  #3  
Old 06-19-2009, 09:00 AM
Bob Kaplow's Avatar
Bob Kaplow Bob Kaplow is offline
Mr. Dual Eggloft
 
Join Date: Aug 2008
Location: Illinois: where our Governors make our license plates.
Posts: 585
Default

Your rocket must be seriously over weight and draggy!

Back in their day, we regularly flew D DEL with D8 motors. The current Apogee D10 would be ideal for a lightweight Dual Egglofter. If yours needs more than a D21, you've got the wrong rocket.
__________________
I fought the law, and the law LOST!
Reply With Quote
  #4  
Old 06-19-2009, 11:31 AM
chanstevens's Avatar
chanstevens chanstevens is offline
Rocket buildin' machine
 
Join Date: Jan 2007
Location: Cincinnati OH
Posts: 520
Default

Depends also on how you're launching it and what you're trying to accomplish.

Example--for BT-80 and D21 combo, I'd go at least 3/16 rod if not 1/4" and probably want 4-6 feet of rod, especially if there's some wind.

What sort of capsule are you protecting the eggs with? You mentioned dual, and a D21 tends to really spank them at the thrust spike, so good padding in between them is critical. A lot of duals get DQ'd for eggs bumping into each other and cracking.

If your goal is qualifying, you've probably got a decent rocket though big/heavy. You'll certainly deploy low, won't thermal away, so recovery will be fast and probably secure. If you want to win something (regional, NARAM), you need a much lighter model and a whole lot more chute, plus a good set of hiking boots, as modest winds will probably result in 1/2 mile minimum recovery treks for anything flirting with top-4 times.
Reply With Quote
  #5  
Old 06-19-2009, 04:07 PM
garmtn's Avatar
garmtn garmtn is offline
Craftsman
 
Join Date: Sep 2007
Location: Great Meadows, NJ
Posts: 188
Default Dual Egglofter

We're competing in a local club/NAR meet. I discovered a plastic soda bottle is much lighter than a BT-80 nosecone. So that should shave off several ounces. I have a strong double chambered "mailing tube to house the eggs. Packing peanuts and pipe wrap for padding. Also, a "quick deploy" 36" nylon chute. Just keeping my fingers crossed.
Reply With Quote
  #6  
Old 06-19-2009, 04:19 PM
Bob Kaplow's Avatar
Bob Kaplow Bob Kaplow is offline
Mr. Dual Eggloft
 
Join Date: Aug 2008
Location: Illinois: where our Governors make our license plates.
Posts: 585
Default

Quote:
Originally Posted by garmtn
We're competing in a local club/NAR meet. I discovered a plastic soda bottle is much lighter than a BT-80 nosecone. So that should shave off several ounces. I have a strong double chambered "mailing tube to house the eggs. Packing peanuts and pipe wrap for padding. Also, a "quick deploy" 36" nylon chute. Just keeping my fingers crossed.


WAY too heavy. Get a Pratt capsule, or whoever is currently selling the old Apogee capsule (Custom?) with an extension tube. Even the old Estes Scrambler cone would be lighter than what you're describing. I just ran down to the dungeon. One of my old grungy egglofters with dual capsule and 36" chute weighs 50 grams minus motor and eggs. With 2 eggs and a D10 it would be around 140g.

What does your model weigh?
__________________
I fought the law, and the law LOST!
Reply With Quote
  #7  
Old 06-19-2009, 04:58 PM
garmtn's Avatar
garmtn garmtn is offline
Craftsman
 
Join Date: Sep 2007
Location: Great Meadows, NJ
Posts: 188
Default Dual Egglofter

I use a BT80 and some heavy duty hardware. The force of ejection ripped my baffle system right out! To answer question, before I shelved the standard BT-80 balsa cone and put on a soda bottle nosecone, it came in @ 18.2 ounces.
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump



All times are GMT -5. The time now is 06:17 AM.


Powered by: vBulletin Version 3.0.7
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Ye Olde Rocket Shoppe 1998-2020