Thorp Air Command - T18.net

Hey everyone, I am in the process of swiching out my prop with the one that came with my project many years ago. My project also came with an uncut aluminum spiner and front and back plates.

My first question is my prop is 3.75" thick, but the distance between the front plate (when tight in the spinner) and the back plate is only 3.55". The prop won't compress that much will it? If the plates were farther appart than the prop thickness I could shim with a spacer but I don't know what to do since the sacing is less than the thickness of the prop...

Second question, any good tips on cutting the openings for the prop other than just starting under sized and then triming to fit. My main concern is making sure the openings are straight accross from each other.

Third and minor question. How many nut anchors and screws do you guys use to attach the back plate to the spinner. My fiberglass spinner has 6 on a side. I was thinking 5 on a side with the aluminum spinner?

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Matt Smith
Des Moines, IA
55RC

Matt,
Go to EAA s site and search for Tony B's writeup on installing spinners, as always his articles make things easy!!!

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Lee Walton
Houston, TX
N51863,N118LW
KEFD

Matt, I just finished cutting a blank spinner for my plane. You need to start with the correct diameter front plate for the thickness of prop you intend to use. Not running a front plate on a long t-18 spinner is not recommended.
Cutting out the slots looks harder than it is. Make a paper template using the old spinner and fit to the new prop, use tape to build up areas if needed. Cut out with jigsaw and finish with hand file.
I used ten #10 nut plates on my twelve inch back plate. Chuck

Ok so after reading Tony's article (thanks Lee) and Chucks post (thanks), it sound like I am screwed with the front plate (must be made for a 3.5" hub when I have a 3.75"). I am sure my spinner is 30 years old and not sure where it came from, I am guessing Ken Brock but not positive. I'm open to suggestions.

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Matt Smith
Des Moines, IA
55RC

Matt: I have a couple of used front bulkheads if you can get a measurement I will tell you if they will work. Otherwise I suggest selling what you have and ordering new. Chuck

Matt: Here is 2 links that may help you cutting out the spinner,

http://members.eaa.org/home/homebuilder ... afety.html

http://members.eaa.org/home/homebuilder ... inner.html

Chuck is correct about the use of a fwd front plate highly recommended by the author of the 1st article.

10 screws to attach is also correct.

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Victor J Thompson
C-GIRQ
In memory of Dad

Hi Chuck,

I measured the front bulkhead today. it is 11.0625 Diamiter. Looks like I need somewhere inbetween a 10.9375 and a 10.875.

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Matt Smith
Des Moines, IA
55RC

Following the instructions from Tony Benglis in the Sport Builder Books. Making the paper templates and measuring more than once will help. I think I used a small cut off wheel to make the ruff cut and then used a drum sander to sand to the Sharpie lines .

RB

Matt, cut you two round pieces of particle board, anneal the aluminum, clamp it between the wood and make yourself one.

My used bukhead is 10 7/8 if you think this might work let me know. Chuck

Is it drilled for 3/8" bolts?

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Matt Smith
Des Moines, IA
55RC

Matt, drilled for 7/16 bolts. Chuck

Chuck, does it just have the one set of holes so I could just drill a new set inbetween? If so then how much do you want for it?

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Matt Smith
Des Moines, IA
55RC

Hi everyone,
What is the thickness of your front bulkhead. The one that came with my project is 1/16" aluminum. That is why I am so apprehensive about forming one. I have heard that I could use as thin as .032 for the front bulkhead. If that is true then it should not be hard to make one. Is .032 thick enough. I have a some of that on hand.

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Matt Smith
Des Moines, IA
55RC

.032 is fine Matt

_________________
Lee Walton
Houston, TX
N51863,N118LW
KEFD