Geoff_H

Sorry second time is edited a little better. Voice to text is something that I still have to master.

For those who don't know how a gas turbine is limited. Stiometric combustion of the fuel produces a temperature higher than any gas turbine blade known at the moment can withstand. To bring the temperature of the gas entering the first stage turbine the mixture is over aired. Airr acts as a cooling agent. The higher your blade can withstand the less air you have to pump in the compressor so the higher the temperature, the higher the efficiency. Also affecting efficiency is the pressure at which the compressor generates, the GT worked on had a compressor discharge pressure of 250 psi. The pressure is just like the compression ratio of a piston engine the higher the pressure the more efficient. Out of a typical gas turbine the oxygen in the exhaust gas will be around 16%. As this oxygen just gets taken in and heated and exhausted at quite high temperature, a lot of energy that could be going to the output shaft is just wasted. The material of blades the get around 30 to 40% efficiency is exotic the manufacturer is also exotic Pratt & Whitney have a duct up the centre of the blade with small holes radiating out to the leading-edge so that a small layer of cool air runs along the leading edge of the blade. These materials are exotic the burner I found more expensive than the actual blading. For a 60 megawatt gas turbine used for electrical generation the rehabilitated cost of burners for the machine was $5000000 the cost of blades for the same machine was around $5000000. The control system of a gas turbine or run with as much fuel as you can get in before you reach the turbine inlet temperature Max for blade life. All expensive stuff.

For those who don't know how a gas turbine is limited. Stoica metric combustion of the fuel produces a temperature higher than any gas turbine blade known at the moment can withstand. To ring the temperature of the gas entering the first stage turbine the mixture is over Ed air acts as a cooling agent. The higher your blade can withstand the less air you have to pump in the compressor so the higher the temperature the higher the efficiency. Also affecting efficiency is the pressure at which the compressor generates the ones I worked on we had a pressure of 250 psi full stop this is just like the compression ratio of a piston engine the higher the pressure the more efficient. Out of a typical gas turbine the oxygen in the exhaust gas will be around 16%. The material of blades the get around 30 to 40% efficiency is exotic the manufacturer is also exotic Pratt & Whitney have a duct up the centre of the blade with small holes radiating out to the leading-edge so that a small layer of cool air runs along the leading edge of the blade. These materials are exotic the burner I found more expensive than the actual blading. For a 60 megawatt gas turbine used for electrical generation the rehabilitated cost of burners for the machine was $5000000 the cost of blades for the same machine was around $5000000. The control system of a gas turbine or run with as much fuel as you can get in before you reach the turbine inlet temperature Max for blade life. All expensive stuff.

Search Micro Turbine. They are available, reliable, and can do 200hp. They are industrial so have a bit of conversation. I couldn't afford them. https://en.wikipedia.org/wiki/Microturbine

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.alstom.com/press-releases-news/2012/6/the-new-alstom-gt-24-gas-turbine-shipped-to-mexicos-el-sauz-combined-cycle-power-plant&ved=2ahUKEwicgKvnmrTyAhVb63MBHeRSC20QFnoECAYQAQ&usg=AOvVaw31Xwr2oa8X01zyEdA972BS A subsequent burner, industrial size. I think that GE also have one.

I must admit that Microturbines are proven. A friend was involved with them. I got the price....$$$ compared to piston. Maybe one day I will design, but not build ( far too old lol) a dual burner turbine. I maybe wrong but for the addition of a burner over conventional turbine they might just have less weight for the same power.

Turbaero have you guys looked into using two stages of burners. One before the first stage turbine and the other before the second stage turbine. All blades in both stages would have to be of material and construction that is what you would make them now. But this would allow a theoretically double the amount of fuel to be burner for the same compressed air flow. In fact it would be significantly less than double butuch higher than single. I don't know much, one day I may get enthused and make a stab at calculating how much. Efficiency gains are obvious with so much less power needed for the compressor. Not my idea. In the later 90's ABB designed a very large GT using this theoretical design. An enthusiastic salesman sold a power station full! They didn't work as well as expected. The liquidated damages nearly sent ABB broke. I have always thought that this might be a simpler design than using turbine exhaust to heat turbine inlet air. Might be cheaper, but I doubt that. Blades and burners are not cheap.

Maybe you could help me. The slower that a turbine goes the more power it gives out. Why does the PT6 have a gearbox rather than just run the turbine slower? I have quessed it is for efficiency reasons. One day I will sit down for a day or two and try and calculate it. Any thoughts?

Class is a function of tit. Most commercial turbines in Australia are class C. GE have a class H. The turbine that I worked on was 180MW, and had blade leading edge cooling. I believe that you are using heat recovery, a great idea. Best of opportunity. Great to see you succeed.

I worked on the desk of industrial gas turbines in Florida. We used Pratt and Whitney blade technology. I am interested in your blade technology and how you are going to build them in Australia. What can you tell me about yours? What class of turbine will yours be?

Why?

In the 7 years that I had the Mooney J I spent $120k on improvement and update. On a trip in the outback into the wind having a Cessna say he could only get 90kts owing to wind. I had 130kts. If you beat a Cirrus by 1 minute, it was worth it. Never flew other than throttle to the wall. I only sold it because the wife refused to fly anymore. So doing a once around the block after a long drive to the airport from Sydney I have in to her wishes and sold it. I would like to do aerobatics. Looking at doing that soon

Mooney owners don't care about the cost. Read the story of the M20J development. The number of go faster things around is huge. Eg aileron seals USD 2k speed increase 2kts. Most Mooney aircraft have heaps spent

Actually exactly the same inside dimensions as a Cessna 172. I won a bet on that a few years ago. The inside does look smaller, quite deceptive

People who buy Mooney aircraft don't usually care about fuel economy, just speed. Lol.

After Mooney released their latest model Sirrus released their latest model. It was a little faster than the Mooney, Sirrus claimed the title to fastest production aircraft etc. However Mooney had an ace up their sleeves. They announced a change to the propeller on their latest model and free issued it to all that had bought that model. They regained the title!

I remember once that I could not retract the U/C on my Mooney, usually good for 170kts. With the dirty U/C down the max speed was 120kts.

I once read an article and if my memory serves me right, it was about CA retractable Cherokee. The author said that the extra weight of retractable reduced speed of the aircraft, the lack of drag increased the speed. It was claimed that it only gained 5knots. Hardly worth the expense. I expect that the extra weight would push the landing speed above the minimum. The aircraft seems to be risky to purchase. Iay have to remove the retractable.

How is stall speed of a modified RAA project determined? Using manufacturers data and calculations of weight effect on stall speed or by observing on landing? Looking at a project that can be expected to have a weight increase based on modification. But not sure it will have stall speed above RAA max

I found another partly finished project for sale. It is the right weight and landing speed but has retractable undercarriage. I thought that this was not allowed in Recreational aircraft. Am I right?

I await your advice on availability, let me know. I will suspend my research. Cheers PS I still have not found a property to store my current project

Skippy you don't seem too keen to sell. Maybe you will do it yourself! When lockdown is finished I will contact you to see if you are still selling. If so I will go to the Oaks.

What constitutes a tyre kicker? Someone that looks but doesn't buy? I once bought an aircraft on first sight. A stupid purchase. These days I do much more research. Seen quite a few aircraft, only bought one. Sometimes one does research by seeing what is available and prices until a real bargain is discovered or that special aircraft is found.

I could not agree more. I love building and fixing things far more than flying. I am a career engineer. I was 14 when I found out what an engineer was, that was the moment I knew I was going to be. Even in retirement I still love being an engineer.

At the end of the day I feel that it is a risk vs benefit issue