Logo
Builders' Plan Gallery  |  Hip Pocket Web Site  |  Contact Forum Admin  |  Contact Global Moderator
April 23, 2019, 04:27:31 AM *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with email, password and session length
News: Help Support Hip Pocket Aeronautics Builders' Forum and Plan Gallery

You can help support our forum and gallery
by having plans printed by Ratz.

Details and Feedback here: Help Support the Forum & Gallery - Plan Printing
 
Home Help Search Login Register
Pages: 1 [2]   Go Down
Print
Author Topic: P30 rubber sizes  (Read 2444 times)
0 Members and 1 Guest are viewing this topic.
applehoney
Titanium Member
*******

Kudos: 276
Offline Offline

Canada Canada

Posts: 3,133




Ignore
« Reply #25 on: February 04, 2019, 03:47:43 PM »

A  Gizmo nose assembly or, alternatively, a spring stop on the shaft obviates 2 pegs ..and no braiding required
Logged
randoloid
Silver Member
****

Kudos: 7
Offline Offline

United States United States

Posts: 120



Ignore
« Reply #26 on: March 04, 2019, 08:10:18 AM »

Can someone please let me know the weight a P30 rubber motor should be
l would very much appreciate it thanks

10 gram limit
Logged
applehoney
Titanium Member
*******

Kudos: 276
Offline Offline

Canada Canada

Posts: 3,133




Ignore
« Reply #27 on: March 04, 2019, 09:31:56 AM »

10g lubricated.   9.5g is safe
Logged
skyrocket
Gold Member
*****

Kudos: 28
Offline Offline

United States United States

Posts: 659

nothing hard is ever easy



Ignore
« Reply #28 on: March 05, 2019, 01:24:34 PM »

I have been using 12 x 1/16" for the past couple of years and like it very much...9.5 grams before lube...with a orange Chinese prop...short motor but a great punch for altitude coupled with a high aspect ratio under-cambered wing...this set up does have its problems with D/T but if you pop the wing, okay....sad to hear of John Barker passing. His Hep Cat is a hoot to fly and very dependable. He always gave sage advise on this web site.
Dave
Logged
cglynn
Gold Member
*****

Kudos: 8
Offline Offline

United States United States

Posts: 350



Ignore
« Reply #29 on: April 05, 2019, 02:28:13 PM »

Maybe Bill was just trying to make up the right size motor from some May 99 TAN II rubber that could not be stripped to make a single loop Smiley

I talked to Bill about that at a contest.  That is exactly what happened (though I think it may have been 3/02 rubber).  The thought is in indoor that rubber cross section size does not matter, but weight per length does matter.   When Bill tied his scrap rubber strands into a motor for an F1N, he was only paying attention to loop length and weight.  Reason being a given weight and length of motor will store the same amount of energy as a different motor of the same length and weight.  Testing showed that it doesn't really matter how you achieve that weight and length.

Now, slight caveat.  For indoor, the motors are very rarely over 3g, and usually much less than that.  So a single loop makes sense.  For outdoor flying, multiple loops are required due to the mass of the motor.  When flying motors of significant weight and strand count, greater number of strands is preferred.  I have been told that this allows for one of the strands to possibly break, but because it is surrounded by many other strands, it will not blow the whole motor. 

Those with more outdoor experience, feel free to add.
Logged
Tmat
Titanium Member
*******

Kudos: 67
Offline Offline

Canada Canada

Posts: 2,924




Ignore
« Reply #30 on: April 05, 2019, 02:56:23 PM »

The thought is in indoor that rubber cross section size does not matter, but weight per length does matter.   When Bill tied his scrap rubber strands into a motor for an F1N, he was only paying attention to loop length and weight.  Reason being a given weight and length of motor will store the same amount of energy as a different motor of the same length and weight.  Testing showed that it doesn't really matter how you achieve that weight and length.
It seems to me that if we assume that the rubber density is close to uniform across a batch, or segment of a batch, then I'd argue that weight per length IS the measure of the cross section. And I imagine that if it's tricky to accurately measure small motor cross section (it's not metal and is squishy 'cause it's rubber!) then weight per inch is a more sensible way to determine it.
Then 3 strands that weigh the same per inch as 2 strands should be the same equivalent cross sectional area and thus give similar energy.

Tmat
-but what do I know?? :-)
Logged

F1B guy...
But don't hold that against me!
Pages: 1 [2]   Go Up
Print
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines Valid XHTML 1.0! Valid CSS!