Posts: 843
Joined: 2/12/2002 From: Richmond Hill,
ON, CANADA Status: offline
I felt like it was Christmas today. Check out what I just unwrapped less than an hour ago!...
What do you think? How do you like the look of it?
Notice that I don''t have any picture of it on my H9 Corsair. The reason is that it doesn''t fit on the engine!
Here is a list of changes that will occur on the production run:
1) The hole on the rear hub half was drilled about 0.0025" too small, and it doesn''t fit around the unthreaded part of the prop shaft. I''ll tell the CNC operator to fix this in the production run.
2) The hole on the front hub half was drilled too small (also not by much), and it doesn''t allow the 13mm extension bolt to fit through it. I''ll tell the CNC operator to fix this in the production run.
3) The inside diameter of the collar on the front hub half was cut perfectly. But the Tru-Turn hub (the dome piece in front) which is supposed to have a diameter of 1.25" has an actual diameter that is 0.025" smaller. This one is my fault. I didn''t take the actual measurement of the hub. Instead I just used the number that Tru-Turn states on the packaging. This one is purely cosmetic anyway. It''s a very loose fit, but when everything is bolted down, it will sit perfectly in the center and you won''t even notice the gap. I''ll send Tru-Turn an e-mail asking about tolerances, then I''ll re-size the ID the collar sized appropriately in the production run.
It''s not a bad situation at all because everything is easily fixable. I''ll go back to the machinist made the actuator and ask him to bore out the holes in the front and rear hub halves. Then I should be able to mount it on the engine and take pictures of it on the Corsair.
The good news is that everything on the inside of both hub half fits perfectly. The blade roots seat nicely and firmly in the hub.
Posts: 730
Joined: 9/1/2006 From: atlanta,
GA, USA Status: offline
I like the small gap looks more scale to me JMHO .the full size one had a locking ring to hold the spinner on and that gap simulates the same on your 1/8 scale version heres a link to a good pic of what i am talking about very first pic keep up the fantastic work http://www.rcuniverse.com/forum/m_7335038/mpage_2/key_/tm.htm
< Message edited by cimara -- 4/15/2008 1:34:41 AM >
Posts: 2159
Joined: 12/6/2003 From: Northridge,
CA, USA Status: offline
I think that Soloprops should hire you! They have a good idea, make a variable pitch prop/hub system. You have a great idea, make a variable pitch prop/hub system that looks more scale!! And in a popular scale size too!!!
Posts: 843
Joined: 2/12/2002 From: Richmond Hill,
ON, CANADA Status: offline
The hub can''t fit all the way down the prop shaft (yet). It can go on but it will get stuck once it reached the unthreaded part of the prop shaft, which is about 3/8" short of reaching all the way to the engine''s drive plate.
So to take these pictures, I cheated by unscrewing the cowl and sliding it forward a little to cover the gap between the engine and the hub.
These pictures make me realize that I need to paint my dummy radial.
Posts: 843
Joined: 2/12/2002 From: Richmond Hill,
ON, CANADA Status: offline
Now that I got the hub, there a lot to do and a lot to tell you, but I didn''t have much time this evening to work on the hub (regular life sometimes gets in the way of RC ).
I did get the machinist to enlarge the holes in the front and rear hub halves. Just 1 or 2 thousands of an inch did the trick. Now, as you can see, I am able to bolt everything down unto the engine now.
The sophisticated rig in the pictures is what I''m going to use to measure the following: 1. Pitch of each blade. 2. Pitch synchronization of the three blades. 3. Blade tracking.
I''ll feel more comfortable firing this thing up for the first time if all these things check out. I guess I should also check the balance. And put it on a weigh scale. Is there anything else I should check before I use it for the first time?
Posts: 843
Joined: 2/12/2002 From: Richmond Hill,
ON, CANADA Status: offline
Thanks for all the kind words. I''ll have the video camera ready for sure!
Now on to business...
These are the things you need to do before you can mount the hub on to the engine:
1) Shorten the extension nut to 16mm or 5/8". I used a Dremmel tool. 2) Enlarge the hold on the Tru-Turn spacer to 13mm or 33/64" diameter. The spacer comes with the Tru-Turn hub. 3) File or Dremmel off a small piece on the pin at the root of each prop. It''s such a small piece that it''s hard to see. Look closely. No need to be exact. File about 1/16" off the end of the pin angled at about 60 degrees. That works out to be 7/64" off the side of the pin. Again, no need to be exact.
In the pictures, I show a pair of each of the above items. The ones on the left are unmodified. The ones on the right have been modified.
I''ll post mounting instructions later tonight.
Josh
< Message edited by Juice -- 4/16/2008 7:01:40 PM >
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RE: 1/8 scale functional Hamilton Standard hub for ... - 
