Thorp Air Command - T18.net

Thanks Rich.

Dick,

The exhaust pulses don't come out at the same time. Th y are like marbles going down the pipe. This is why the area doesn't have to match the area of two pipes.


Jim

We are looking at supplying exhaust for the Thorp. Might be a good time to get started. If desired, we will get a mock up going soon. Any interest?
Cubes

That would be outstanding if that was an item we could buy from Thorp Central!

I like the idea but there may be to many variables in what people want. I currently have 4 pipes, looking to change to a crossover but not fond of the offerings I have seen so far. Now I am thinking maybe a Glassair, experimental Super Cub exhaust or a custom build from Custom Aircraft Parts.

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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

I have the standard right side left side exhaust on my t18. I know there is a performance increase in the crossover exhaust but is it enough to be worth the cost of buying new exhaust for my o290?

Basic physics says that any small percentage increase won't effect speed much in an airplane although maybe the exhaust could improve a little fuel economy or take off roll?

According to some AC engine dyno work I've read a straight four pipe makes the most power. They are as the name implies a simple straight forward exhaust system, making them a very economical choice. I plan to put one on my new O-290 project.
You are going to need to talk to the man but Cubes may have them in stock soon.

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http://www.dixiefriedfabrication.com/

The thing I am running into is the space required for 4 pipes instead of just 2. I am losing paint, rubbing cowling and my fuel line to the carb is a little close for some people to be comfortable with even though I fire sleeved the hose and it is showing no signs of heat stress (I can put 3 fingers between the nearest exhaust pipe and the fuel line). Really, I would prefer a set of Y-pipes to crossovers if I could get them properly tuned but some cleaner routed straight pipes might be better. My current exhaust is composed of sections of curved and straight mild steel cut and pieced together. I think it would help if they could be routed like a "Y" and have them secured together below the rear cylinders so they run parallel to the bottom of the firewall. Unfortunately, I don't have a way to bend stainless tubing that diameter or I would experiment.

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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

When I built mine I welded couplings in the ends of the stainless pipe I had and screwed in plugs. I filled the pipe with sand and took them to the local muffler shop guy. I also took along another system to show what we were duplicating. He bent them on his machine for a bargain price. They wrinkled a bit on the inside of the bend but not enough to bother me. Then I just pieced them together which was the most difficult part trying to get the Y's to fit properly. I don't aim for perfection, I am not that good of a welder anyway.

Pshaw! You are extremely talented!
Cubes

Has anyone had trouble with straight pipes? I have been talking with an exhaust system builder and he is pretty vocal against them. The problem seems to be in properly supporting the tailpipes to keep the stacks from breaking off at the mounting flanges. I like the idea of more power and economy but I don't like the idea of getting stranded somewhere with a broken exhaust stack and a ruined cylinder.

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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

I have springs that support the aft end of the exhaust pipes, the other end is supported by an Adel clamp attached to the cross member on the landing gear.
Phil
118 BC

The straight pipes I've looked at are one long tube. I can see where vibration running up that tube might cause some cracking. So they may need to have a joint in them despite being a simple straight tube.
I think having a grudge against straight pipes cuz they crack is kind of wonky. If it is a problem it's due to the construction/design of that manufacture, not the basic concept.

P.S. mandrel tube bender under construction.

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http://www.dixiefriedfabrication.com/

Just installed a new crossover exhaust system but I have some concerns. This new system is really tight around the oil sump. There are two places where I cannot slide a finger between the sump and the exhaust. Is this likely to cause a problem?

I have 2 places where the exhaust is too close to the intake tube coupler hoses but making deflectors for those was easy. I iust took some heat shield and hose clamped it around the intake tubes but the sump isn’t as easy if it is needed.
Thanks

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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

PSA heat shield .

RB