Mailing List flyrotary@lancaironline.net Message #24097
From: Richard Sohn <unicorn@gdsys.net>
Subject: Re: [FlyRotary] Re: re-drive question for George and Richard
Date: Sat, 18 Jun 2005 07:57:36 -0700
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Message
George,
 
yes, the 85lb is just the block as it is running now. The FF, dry, will be 170lb. Keep in mind it is 12A based. The 13B based will be a bit heavier.
 
 
Richard Sohn
N-2071U
 
 
----- Original Message -----
Sent: Friday, June 17, 2005 11:23 PM
Subject: [FlyRotary] Re: re-drive question for George and Richard

Rusty,
I compared my weights with yours, I'm using some old bathroom scales (accuracy is suspect) but we agree ( more or less) on the engine weight savings.
I didn't take into consideration the savings on radiator, rad fluid, oil or accessories as I didn't think that would amount to much.
Here's hoping your right, like I said I like your figures sound better than mine.
Did you see Richard's weight claim 85 lbs, but I doubt if that's an all up wet weight. I did notice he had a aluminium end housing ( front) and a small PSRU.
Richard you wouldn't have al all up wet weight would you - it's looking good. I'm guessing 185lbs!
George ( down under)
I would like to know where I went wrong or what I forgot to omit as I like your figures better Rusty. Don't tell me oil!!
George ( down under) 
 
Well, mine's still just an estimate too, but not for much longer :-) 
 
Below is how I estimated it in my log.  These are 2nd gen weights BTW, not REW, which are a bit lighter I think.  As you can see, I calculated 216.5 lbs, and rounded that up to 230 lbs to be conservative. 
 
Cheers,
Rusty
 
 
 

13B parts:

 

Front iron housing- 23 lbs

Center iron housing- 28 lbs (with dipstick and filler tube)

Rear iron housing- 27 lbs

Each rotor housing- 13 lbs

Each rotor with seals- 10 lbs 9 oz

Water pump housing- 3 lb 2 oz

Water pump- 5 lbs 9oz

Eccentric shaft- 14 lbs  (estimate a single rotor would be 5.5 lbs less)

 

A bare 13B engine is known to weigh 190 lbs.  The items in red above would be removed from this base weight.  The total of these items is rounded to 66 lbs.  That brings the base engine weight to 124 lbs.  Aside from the redrive, which will be the same, the rest of the weight will be literally half of the 13B installation weight for other items.  We often claim 330 lbs FWF for a 13B.  If the basic engine weighs 190 lbs, then the “other” stuff weighs 140 lbs.  If the redrive is 45, then the items that can be cut in half weighs 95 lbs.   So, the single rotor engine is 124, plus 45 for the redrive, and 47.5 for half of the accessory weight.  This is a total of 216.5 lbs.  If Racing Beat ever finishes their aluminum housings, this would be around 190 lbs.    
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