Thorp Air Command - T18.net

Supporting Owners, Builders and Pilots of the Thorp T-18 and its variants.
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SHIPCHIEF
PostPosted: Thu Jul 13, 2017 1:29 am 
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Joined: Tue Nov 29, 2011 9:05 pm
Posts: 429
Location: USA
Using you're weight and balance from the spreadsheet, and Bruce's fwd and aft limits, I'd say you are in pretty good shape.
I just want to know? did you take the lead off of the engine before you weighed?
Can you make your preferred changes and re-weigh the plane quickly?
Bruce and I are pretty lucky, our EAA chapter has a set of scales, so we can weigh often and for free.
Re-weighing is always better than trying to calculate the moment of the parts that have been added, removed or relocated...

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Scott Emery
EAA Chapter 326
T-18 N18TE


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Jeff J
PostPosted: Thu Jul 13, 2017 7:19 am 
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Joined: Wed Aug 31, 2016 8:18 am
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Location: eastern OK
I left everything where I found it except for the wheel pants to do the weigh. Either I am missing a drawing I need or there isn't any CG information to be had on them and I didn't have a copy of the W&B that came with the airplane so I made my own using information I could find searching the forums and news letters. I think I used the % chord numbers that seemed to come up most often with a reference to a T-18.

Just playing with the numbers, it looks like I should be able to remove the lead if I move the battery from the aft part of the baggage area and mount it on the firewall. The scales I have access to aren't very convenient to use (roll around balance beam scales) but I have unrestricted access for the next couple of months if I can find the time to make changes. I was planning on reweighing it if I get the changes done in time but I don't mind doing W&B revisions and weighing again some time down the road.

One of the hose fittings for the remote oil filter is leaking and, since this filter is plumbed to only filter hot oil, I figure it is a good time to remove that entire assembly to free up space for the battery. Even though the oil screen probably wouldn't have to be checked with the filter at every oil change, it should still be checked regularly since it will accumulate bits of carbon and other debris so I don't see where there is enough of an advantage to justify having both.

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Thorp T18
O-320-B3B (160 HP)
68x74 Sterba Propeller

"The joke in aviation is, 'If you want to make a million, you'd better start with £10m.' " -Bruce Dickinson


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Jeff J
PostPosted: Mon Aug 14, 2017 9:31 am 
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Joined: Wed Aug 31, 2016 8:18 am
Posts: 420
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Location: eastern OK
I removed the filter and screen to install a B&C 700 oil filter adapter with spacer over the weekend. The new unit didn't have the required clearance on my set up. When I cleaned the screen and filter element I discovered the screen was much dirtier than the filter. It's only about 25 hours since major so both would have been done then. Obviously the filter was catching finer particles missed by the screen but the hassle of having both isn't worth it to me so I reinstalled the screen and went flying. I will be exploring other filter options but for now I will run it the way Lycoming built it.

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Thorp T18
O-320-B3B (160 HP)
68x74 Sterba Propeller

"The joke in aviation is, 'If you want to make a million, you'd better start with £10m.' " -Bruce Dickinson


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Binder
PostPosted: Mon Aug 14, 2017 10:03 am 
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Joined: Thu Sep 01, 2016 10:50 pm
Posts: 249
Jeff J wrote:
I removed the filter and screen to install a B&C 700 oil filter adapter with spacer over the weekend. The new unit didn't have the required clearance on my set up. When I cleaned the screen and filter element I discovered the screen was much dirtier than the filter. It's only about 25 hours since major so both would have been done then. Obviously the filter was catching finer particles missed by the screen but the hassle of having both isn't worth it to me so I reinstalled the screen and went flying. I will be exploring other filter options but for now I will run it the way Lycoming built it.



I thought about using one as well although my silicon levels in my oil analysis has never been any measurable amount. Since I change every 25 hours anyways Blackstone said it most likely wouldn't change anything worth the expense. I decided against it and will continue to do what I'm doing. If I start getting more silicon into my oil I might switch then but I'll stay with my 25 hour interval since most oil testing shows 30 hours is about the limit of saturation with the 2 major aviation oils.


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Kim Nack
PostPosted: Thu May 24, 2018 4:31 pm 
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Joined: Sat Oct 24, 2009 12:21 pm
Posts: 2
Location: USA
Just finished my weight and balance affected change to my Thorp.

I have become heavy and creaky in my old age. Flying my standard T18 was getting very difficult. I am 6 ft 6 in. tall at 325 lbs. I have owned and flown my self built aircraft, seems like my whole life. But I could not see many more years of flying it. Giving up flying my plane was difficult to contemplate.

Found a T18 in Winter Haven, FL. that had canted seat bulkhead moved aft 2 in. CG change was not too much of a problem to deal with. It had big IO-360 engine and constant speed prop. I have O-320 and wood prop.

I was encouraged and thot I could move my canted bulkhead 4 in. aft. I moved PC680 battery from behind seat to rh side of firewall as seen in pic on this web sight.

Was amazed at how much better my body fit with every thing moved 4 in. away from my set back, now located farther away.
Foot angle was now natural instead of having to pull toes back constantly. Knees cleared bottom of panel. Hand and control stick had more room to move between knees. Side of leg cleared flap control mechanism. Left arm had more room between my belly and side of fuselage with hand reaching farther forward. Because I could lean more forward, I had more headroom.

I think I gained more benefits than just a wider fuselage would have provided.

The weight and balance showed that the use of the baggage area would be limited, but for me, it is a worthwhile compromise. Using CG range of 62.5 to 71. I can still use cushion to keep passenger forward. Used chapter electronic scales.

Additional comments: Canted bulkhead had to shrink vertically and horizontally to account for mold line changes.
Flying, especially landing, is much easier. I now am enjoying the hope of a little more time flying what I built.


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