Thorp Air Command - T18.net

I think bleeding brakes is bleeding brakes whether it is done from the top or the bottom. I prefer to use this with a catch bottle inside...

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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

That's how I always do it on the bikes and cars. Pressure bleed works like a charm!

When I said an hour I figured in taking off the wheel pant cuffs and bleeding BOTH brakes . Not a bad idea (flushing out the old dirty fluid) if they haven't been done in the last 10 years ! I bought one of these ATS pressure bleeders when I was building my rocket (worked like a champ when I did my first brake set up and had the adapter to attached the ATS hose directly to the bleeder screw , no clear tubing required .) , but the last time I bled my brakes (bottom up) I used a pump oil can as shown on the EAA site . Found a quality USA made oiler with a metal flex spout and attached the clear tubing as indicated in the video . Worked as well as the ATS bleeder and cost about $20.00 to make . Funny thing about the ATS bleeder is that the original one I had failed at the welded plastic seam and leaked fluid all over my floor ! Wrote to ATS and even though the bleeder I bought was out of warranty they sent me a new bleeder tank (less the hose) . I guess they found the early tanks had a habit of failing at the seam and up graded the tank material . The bleeders now carry a lifetime warranty .

RB
BOOM , CHICKY BOOM !

I have tried a lot of different things over the years. The thumb pump oil can works well and I also had good success with a hand crank fuel pump for radio control models. I did try a few different homegrown setups similar to the ATS tank but all of those failed (usually they couldn't tolerate the 5606). Since I buy 5606 by the gallon and it seems to be hard to locate cans that can be opened and resealed, the ATS tank makes for a good storage container as well as gives me the freedom to get out from under the aircraft so I can keep an eye on what is happening at the master cylinder. It also acts as a "no spill" dispenser for friends who need to "borrow" some. I think I had mine for 6 years now. Not all systems are feasibly bled from the bottom but for those that are, the oil can, fuel pump and pressure tank work well. What is "best" depends on your level of usage.

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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

It took me 35 minutes including the time it took to get out the tools, manufacture a new catch bottle (2 attempts ending with a cut up pop bottle wedged under that master cylinder), bleed one side and put everything away to bleed the right brake. My "normal" catch bottle isn't compatible with the Matco master cylinder and I didn't know that was what I had until I crawled in to connect. I need to position a gantry crane over the aircraft so I can hoist myself in and out instead of flopping around like a fish trying to get a hold of something to pull on.

I wouldn't bleed brakes from the bottom without a clear tube somewhere so I can see if I am forcing air into the brake system. I have too many years of experience to allow myself be the reason there is air in the system or, if I am the cause, not to catch it the moment it happens. Things like that only cost me money because I won't charge a customer for my screw ups.

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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

Binder, back to the important stuff!

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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

Sorry, with a couple threads going I sometimes forget which one is active.

As for the plane. Unfortunate news is the CFI picked up a ferry job that takes a plane to russia tonight so he won't be back until next friday. I'm signed off on insurance and my endorsement but not quite comfortable flying alone yet in this plane so no flying this weekend to test.

This past weekend I pulled the ma3spa carb off the plane. It had some varnish build up on the venturi but the jets were clear. I inspected the float which was perfectly intact, no leaks and no dents. It is a brass float. I didn't have a piece of clear tubing to check its level yet so I just re-assembled the carb and put it back on. I also put a new friction lock throttle in place of the horrible veneer type throttle. When I turned fuel on the needle valve was hung up for a couple seconds causing fuel to get on the air filter. I opened up the air box and let it dry overnight just to be safe when I try to start it. Here in a few minutes I'm heading out to do some static run ups. While I was behind the panel I also found out why my VOR wasn't working and I hooked it back up. I need to re-wire that whole panel as it's a mess back there.

Things i'm testing on run up:

Stumble with throttle advance
Static RPM
Performance with full power when I slowly lean the plane out (checking if rich or lean)
RPM increase when pulled back to idle circuit and mixture pulled back. I think this should be 50 rpms. From the raise I can also adjust that idle mixture.

If for some reason I can't get that to improve I'm thinking of just adding a Rotec throttle body injection like David Read has. It's only 800ish for the kit which is cheaper than any advertised rebuild on my ma3spa (and that is if they even have parts for this discontinued carb). The only downfall will be time since I will have to build a new intake box for the throttle body. That's also a plus side because it's using an old car airbox that I don't like.

So if people have pictures of their intake setup I would appreciate ideas. Also, when putting in the new throttle I had a hard time getting it set up perfectly smooth. There is a clamp that holds the end piece of the cable just before the attachment to the carb. The only issue is it's a static clamp and with throttle movement the carb throttle arm needs some up and down flex in that mount to be more smooth. How do you all get that small amount of flex up and down as the throttle is moved yet keeping the throttle cable mounted solid so it doesn't move with action? I'd like it to not have that small increase in friction when at the end ranges of operation.

Thanks!

Can you post a picture or two of the how the throttle cable is mounted? I don't know that I will have any useful ideas but a picture might help.

You are correct on the 50 rpm rise at shutdown. There is an idle circuit adjustment on the carb for that.

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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

Will do. Since I'll be out there with sunlight today the pics will turn out better. I've been working on the plane at night since sunset is the same time I finish at the office. Today is billing day so I'm at home!

This might be of some use to you: http://www.insightavionics.com/pdf%20fi ... Manual.pdf

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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

Normally, I think you would try to clamp the throttle cable farther from the throttle arm to allow more of the sheath & cable to flex. Can you fabricate an extension from the current attachment point of the clamp, to move it further back (towards the firewall)?

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John Evens
Arvada, Colorado
T-18 N71JE (sold)
Kitfox 7 SS N27JE

I used the Aircraft Spruce push/pull cable that has an 8 degree swivel on both ends . All 3 of my cables , throttle/mixture/carb heat are all the same P/N and length (makes keeping a spare cable handy) . I used the Van's throttle/mixture cable mounting plate that goes between the carb and the sump to attach my cables . Makes for a very smooth set up...no binding at all !

RB
Boom , Chicky Boom !

I have it clamped at the firewall as well. I have it moved as far away from the carburetor as possible while still clamping on the outside hard metal surface.

Rich,
I use the 8* swivel as well but the clamp is on the hard round barrel of the throttle just after the swivel. I'll look up that Van's bracket and see if I should switch to it.

As for the engine. Jeff J, I forgot to take pics again as I was excited to start testing. The engine fired up with no issues. I had to reset my idle back down to 650 as it was set for 800. On static run up I was able to get up to 2300 rpms now. As I advanced to the last 1/4" of travel the rpms did drop a little. If I backed the mixture out slightly the rpms came back up so I'm pretty sure it's a rich condition at full throttle. Pulling the throttle back about 1/4" also gave me a little higher rpm. Checking the drop with pulling the mixture out at idle showed no rise in RPM before it died although the AP out here said that it's hard to determine on a normal tach because the momentary raise could be faster than the tach reads or the tach accuracy might miss it as well. He said not to worry about it since the engine was running smooth.

It was pretty smooth and doing much better. OAT was around 65* F. I'm not 100% comfortable flying alone yet with this plane so no flying until the CFI I use comes back from russia.

It sounds like it is operating about normal. I think someone else already mentioned the carb will automatically enrichen the mixture at full throttle. From your experience with the Kawasaki I am assuming you know what colors to look for in the exhaust and on the spark plugs to determine the mixture trends.

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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

Ya, I'm going to pull the plugs this weekend and check them. The downfall in aviation with plug readings is getting an accurate read after taxi and idle.

I might have to do the old trick of cleaning them, firing up the engine and running it WOT for a few minutes then shutting it down to get an accurate reading. I do have black under my fuselage so I know it's running rich. That last bit of enrichment is just a little too much on this plane apparently. To have it properly serviced costs more than putting a rotec throttle body injection so I might just switch over to that instead.

The fact that it cleaned up when pulling the throttle mixture confirms my rich condition. Along with the fact that it's 20* cooler than when I was having the rough running take offs.