Thorp Air Command - T18.net

Did some more wiring yesterday behind the instrument panel as well as getting the new exhaust pipe hangers. I also started to assemble the new exhaust pipe hangers.

Next time I go out to the hanger I'm going to make a small plate to cover the hole in shelf over the baggage compartment as well as mount the Stratux ADS-B unit and the USB converter. With the new plate, I'll step-drill a new 1-1/8" hole to accept the USB converter that is in the background of the picture. That converter is only $19 from CrazedPilot.com and has a 1.0 Amp outlet and a 2.1 Amp outlet.

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

Sorry that it's been a while since I've posted. I've been diligently working on the plane on Saturdays and Monday nights. I worked on N12055 three of the four long Memorial Day weekend days. Thanks for your comments in March about the VOR that's not needed anymore. I decided to get rid of the old VOR cable and save weight. I don't plan to fly IFR, and otherwise, if I did need VOR for some reason, I have it on the Yaesu radio.

Some of the things done in April/May relate to replacing all wiring and device mounting:
* Installed the mount for the Yaesu FTA-750L radio
* Installed the mount for my iPhone
* Installed two new switches for Com (Yaesu and intercom) and Nav (Statux, iPad, & iPhone)
* Replaced the flap wiring from panel switch to the baggage compartment trim motor
* Replaced the trim wiring from center tunnel switch through the trim motor in the tail
* Got rid of the old VOR antenna coax wiring in the tail
* Installed the new trim position sensor from Ray Allen and wire it
* Replaced all the grommets in the aircraft, nose to tail (the grommets are old)
* Installed the new pitot/static lines and nifty little push-in connectors for the instruments from SteinAir

For anyone who has bought someone else's plane or project, one important lesson that I learned from crawling back in my plane's tail is that you don't really know what you have back there and even though it's a pain to crawl back there, you must take a look. I think that a previous owner had someone do some wiring in the '80's for the new electric flaps and trim and IMHO the hired "mechanic" did a terrible job. Look at the pictures of the grommets and wire in direct contact with metal bulkheads and you'll see what I mean. That person cut chunks off of grommets away so that the new trim wires could be pushed through the gap. So, be careful and take the time to look. It cost me an extra month to fix it all, but now I know that what I have back there is all new and done right.

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

When I first got my Thorp, I asked the forum how people got back into the tail. I got a lot of answers and the consensus was that it was a pain and hot. I concur. Before I began, I started by building a small table to support the rear fuselage where it's essentially flat. I didn't want the fuselage skin and rivets to support my 170 lb weight and end up bending something. The table only lifted the fuselage a little so that the tail wheel was only 1/2 inch off the floor. Then I built an even smaller support for the port-side baggage compartment floor where it's a little curved.

Make sure to watch out that you remove any belly strobes first and that you don't hit/bend your transponder antenna. Before climbing in, I decided to remove the stabilator and its push/pull tube. I didn't see any other way to have enough room to work. You'll probably want to disconnect your rudder cables at the pedals too. When inside the tail, try to move the disconnected and slack cables off to one side so that you don't rub them against the fuselage floor with your butt and scratch your floor.

On a hot day, you'll need a fan to blow air back there. You'll also want to put something down to protect the fuselage floor metal. I used an inflatable sleeping bag cushion for camping. I found it easier to crawl out of the tail than into it. Crawling into it was kind of like a sick version of the old Twister game - but where a wrong hand placement can cut you. I have a lot of sharp metal here and there at the back of the baggage compartment and it really was a concern. Make sure to take your cell phone with you for pictures and emergency use. You should have a safety person when you're going in and out. I didn't think of that the first time .

I hope this helps anyone who is thinking about how to get back there. Do any of the veteran builders have other suggestions?

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

Hello John, I can give you a little history on 55 (Double Nickel) as Bob called it. It is the second 55 that was built by Bob, the first was the open canopy and it was featured on the cover of one of the newsletters in the late 80's or early 90's, Bob flew it open cockpit from Lombard, IL to Dallas, TX (Dick Cavett) fly in, this aircraft burned in a hangar fire at Mitchell Field, Lombard, Ill in 1966 or 1967 if my memory is right then Bob built the second one. Bob's craftsmanship was first class and this was a very fast O-290. Bob quit flying 1978/1980 and sold it to one of the other builders in EAA 101 who sold it to Ed Burke in PA who flew it to OSH once. I took a picture of it and gave one to Bob and sent one to Ed. Ed's son took the airplane when his dad passed away and I don't know if he ever flew it after he made some modifications to it (gear legs) this was my last contact with 55. I worked with Bob for several years and he passed away in the 90's from Parkinson's disease. There were 5 T-18's built by the members of chapter 101 as I recall and one of which (Al N.) crashed at OSH when a wing separated (think FAA said wrong hardware used). This is all I can think of at present.
Regards, Ed Torbett formerly from IL now TX.

The table is a good idea. Mine has a large panel in th belly behind the baggage area. It wasn’t set up to be removed (screws with nuts) when I bought it but I have replaced the nuts with tinnerman anchor nuts and now have pretty good access to the back.

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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

Caution to builders. JT designed the Thorp using several structural boxes to make the aircraft light but very strong. Cutting holes in the fuselage/wing could defeat these structural boxes, I would use caution when cutting access panels.

The hole in mine was part of the Javelin engine installation. The radiator used to live in there. The center stringer is still there and uncut so it is actually 2 holes covered by one surface mount panel. What I have done to make the hole user freindly is actually stronger than the radiator mount I removed. I didn’t intend to change any of it but once I tried to remove the panel I was committed. I wouldn’t have tried except the easy to see and access screws all had nut plates. I would like to flush mount 2 panels or reskin the bottom but projects that involved have to wait.

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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

Hi All, My business has doubled in the past two months with the acquisition of a new, large customer. I've still made time to work on the Thorp twice a week though, and I just haven't gotten around to get on the forum. It's hard to believe it's almost been two months since I was last on...

First, Ed - thank you for the excellent history about N12055. I really appreciate it! Some of it I knew about, and some is new. I like the info about the 5 T-18's being built simultaneously. I wasn't sure if Ed Burke ever flew it to OSH, so now I know. His son, Doug told me that he himself (Doug) flew it to OSH twice.

Bill - thanks for the cautionary access panel note. My access panel has been in the aircraft at least since Ed Burke owned it, maybe earlier. It's been a god-send to me for working behind the panel on the wiring. My IA has used it already to review wiring, brakes, etc. and I'll ask him during the final inspection after Oshkosh to take a good look at it structurally. He's had no problems with it so far.

I'm looking forward to seeing many of you at the OSH forum on Thursday!
John

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

My wife, Maddie, came out to lend a hand last weekend for my birthday. SH*T's getting serious now!

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

Making good progress!
* Tailcone is cleaned up, rewired, and completed
* All the electrical re-wiring is done
* New trim position indicator is in and tested
* Cockpit is cleaned up
* Instrument panel is completed
* New center console is completed and painted

To Do's:
* finish installing all engine control cables (this Saturday)
* Start the engine and test-run it (starting this Saturday)
* rebuild the brake master cylinders
* replace all the original brake lines
* Taxi testing
* IA inspection
* Transition training (see you soon, Cubes!)

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

Awesome! Keep at it.. A few words of advice.
If the engine is new (I don't remember) or recently topped, do not run it on the ground any longer than necessary. Break in requires high power until the rings seat. I can talk you through that process if you like.
Also, make sure you do the brakes before you run it up. I highly recommend you tie the tail down as well. Most of us cannot run at high power on the ground with brakes only. When I do this, I hook a tow chain around the tailspring, then park the front wheel of my diesel F250 on that chain as close to the tail feathers as I can get.
Be safe!
See you soon.
Cubes

Here's a picture of where I added a Ray Allen trim position sensor in the tail and mounted a corresponding arm to the trim axle. There is about 1" clearance between the sensor and the top of the horizontal stabilator spar. The rod between the sensor and the arm (with the two black ink dots) is yet to be installed.

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

Thanks for that photo John. I'm going to give your setup a try while I still have my tail area open. Thanks again.

Hi Ryan, a couple notes on the above picture.
1. I used an Adel clamp to go around the trim axle. However, I found I had to take the rubber off the clamp otherwise the metal would easily slide inside the rubber. After that, I put some electrical tape under the clamp to cushion the axle from getting scratched or worn from the clamp.
2. Note that the top of the arm is too high and that I marked an arc on it where I wanted to cut it down so it didn't hit the underside of the cover.
3. The Ray Allen position sensor that seemed to work best for me had the .75" slide travel.
4. Ray Allen recommends that a threaded model aircraft rod and clevis be used instead of a thicker, aviation-style. The hole in the position sensor is very small. The picture shows the threaded model aircraft clevis that I installed.

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)

I have a question for the group. I'm getting ready to final assemble the tail. On the two horizontal stabilator hinge bolts, my plane originally had AN365 nylon lock nuts. Since this hinge moves, do most of you use AN310 castle nuts and a cotter pins on this hinge instead? I'm asking in case there is a T-18 - specific reason to use AN365's that I'm not aware of.

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John Twigg N12055 SN.79 Pittsburgh, PA (KFWQ)