lug mounting....

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Well-Known Member
Apr 8, 2004
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Alright just got my order of parts from Red Arrow Hobbies (great stuff!).

So now im gettin reday to start my scratching again.
This is the first thing ive come up with.
Ive always like the design of the Preator. But I wanted to do a little somthing different with it.

You really have to look at the pic to understand my problem or question.

The top lug sticks out further (duh) on the top bt (bt50) than the bottom bt. but the CG is about 4 -5 inches from the bottom so its hard to mount a lug right at the cg because the bottom tube is smaller (bt 20) do you think i could mount a lug on one of the fins futher out inline with the top lug? or would this cause come kinda of problem?

Ill post both the pic and the space cad file for anyone who wants it.


--- oh and the name of the roc (BLue GAMe) is just some creative word arrangement.. it stands for...



yeah a bit streched but, hey who cares. :p
oh yeah almost forgot the sim specs.

length= 2.15 ft.
upper tube is bt 50
lower tube is bt 20
transition is 1" long
fins span from tip to bt base is 7"
empty weight 2.8 oz.
launch weight 3.42
CG 1.68 ft' from tip of nose cone.
CP 1.99 ft' also from tip of nose cone
best simmed motor is B8

Wrasp numbers...

Max Alt. 241.4 ft'
launch rod vel (3ft rod) 36.4 mph
max velocity 83.8
time to max alt 3.5 seconds
all with .75 drag coeffecient. (sp?)

i think that should just about do it ...i mean what else could you possilby want?
what about taking a peice of balsa, putting the lug on it to extend it equal with the other one, and glueing that on (kinda like a loadstar, i think)
I don't see a problem putting it on a fin if everything is carefully aligned.
I think you need to build the FlisKits Acme Spitfire all questions will be answered before flight as it mounts one lug to a fin and the other to a balsa stand (skill level three .....RIGHT).:) :D
Originally posted by rocketdad0934
I think you need to build the FlisKits Acme Spitfire all questions will be answered before flight as it mounts one lug to a fin and the other to a balsa stand (skill level three .....RIGHT).:) :D

well, 3+.... :p

Actually, rabidsheeep has close to the best solution...

I am assuming that your drawing is scale. You say that the CG is 4-5 inches from the bottom. In *that* case, I would question putting *any* launch lug on the upper tube.

Rather, affix one launch lug, at the CG, on a standoff as shown by rabidsheeep. (NOTE: If you do this, make sure your standoff has the grain of the wood running PERPENDICULAR to the body tube (like this [||||||||||||||||] as this will provide the greatest strength)

Or you could use 2 lugs on standoffs (or one on a stand off and one on the fin), each an inch or two on either side of the CG (this is what I do on the Praetor even though it doesn't *need* a stand off (i just think it looks cool on that design :) )) See the attached drawing I did as Figure 9 of the instructions showing the launch lug installation on the Praetor.

hope this helps. Cool design by the way :)
yeah i think mounting one at the cg is best then i don't have to rely much on my ability to align two lugs.

thanks for all the help guys ill def. post pics of construction and finshing.

Cool design by the way

yeah i got the idea from this really cool roc i forget the name thou..... ;)
I would personally use stand offs like in Jims drawing (those are really cool angled lugs Jim). I used stand offs on my last scratch.

The Estes Venus probe has one stand off at the top, and one out on the fin like you were thinking about though. It seems to work.
<<< hey man the banana is the new wave in dancing you better learn it real quick or you'll get left behind.
:confused: :D