kumaros

Hoog76,

Going back to your original post, which I cursorily replied to before. First of all, no question is stupid, we all learn from each other. As you say, lurking and learning from all these websites of people that have done before us what we are still dreaming of, is an inspiration.

As I said in my previous post, the root of your reasoning is sound. While power is important in an aviation engine, torque from low RPMs is essential too, if you want to turn a big, efficient propeller. Gas engines, especially auto-conversions, tend to have peaky torque curves and are thus unable to turn the ideal propeller to the RPMs where they would produce their maximum power. It's like trying to climb a hill in fourth gear. It would help if you'd have an in-flight adjustable prop; that would be like having a gearbox, shifting from take-off pitch to cruise pitch. It's with a fixed pitch prop, however, where diesels come onto their own. Tending to have flat torque curves from 1500 to 3000 RPMs, and peaking in power close to conventional prop turning speeds (like less than 3000 RPM) makes them ideal. What was less than ideal until recently was their weight due to their robust construction, their tendency to knock and vibrate in low RPMs and smoke at high power settings. I went to the URL you gave and saw mostly heavy duty engines from trucks, tractors, earth-moving equipment etc. In my classification of diesel engines: first and second generation of engines.

First generation, plain old clunkers.

Second generation, turbodiesels, common until about 5 years ago.

Third generation, common-rail 4-stroke turbodiesels, currently being used in more than 50% of new cars bought in Europe (the HDI's from PSA, the TDI's from VW, the D4D's from Toyota etc.)

Fourth generation, supercharged and turbocharged common-rail 2-stroke turbodiesels, for the time being in development as future aviation engines, or in miniature form used in K-cars in Japan.

First and second generation you already know.

For some beautiful examples of the third generation go to:

http://www.germancarfans.com/news.cfm/newsid/2041216.002/page/2/lang/eng/mercedes/1.html

and from there take a look at the link with the 30 photos of the Mercedes Benz V6.

Also:

http://www.germancarfans.com/news.cfm/newsid/2041117.004/page/1/lang/eng/volkswagen/1.html

Now, to address your point about redundancy using more small diesels, you could take two smaller (like 1,3 to 1,7 liters, producing about 100HP) common-rail turbodiesels and stick them together turning a common or two counter-rotating props, as the brothers Leon have done:

http://www.infortel.com/cozy/article_english.htm

Daihatsu, a subsidiary of Toyota, has produced some beautiful fourth generation engines. Imagine engines producing a HP per cubic inch (like 50HP from a 40 cubic inch, and 61HP from a 61 cubic inch engine), while burning (in automobile application) less than a gallon per 100km (imagine fuel economy of more than 90 mpg). Take a look at the third one in this engine line-up:

http://www.daihatsu.com/motorshow/tokyo02/eco/

As for myself, being in the initial stages of home-building, I can begin building the airframe and keep my options open, waiting to see what is available in two or three years time.

Kumaros

It's all Greek to me

I've been reading many websites about cozys for a few years now. This has got to be one of the best resources yet.

 

I'm very ignorant when it comes to the details of hp, thrust, props, rpms etc so bear with me if this seems extreme.

 

One of my biggest interests beside a glass cockpit is engines.

 

What I'm confused about is the requirement for larger hp engines. Isn't the main goal to get the prop turning at a specific rpm for maximum thrust?

 

So wouldn't a prop driven by a 60 hp engine turning at 2400 rpm give the same thrust as a prop turning at 2400 rpm by a 200 hp engine?

 

Is a larger hp required since turning a prop at x rpm's has to much resistance for lower hp engines?

 

Would a different prop design with a smaller hp engine work to create the same thrust as a larger hp with a less efficient prop design or would the resistance of the prop be too much for a lower hp engine?

 

Like I said, my knowledge is really limited and I see the formulas shooting across but it might as well be in a foreign language.

 

The reason that I ask is because I'm really interested in diesels. I see a lot of smaller air cooled diesel engines in the 30-60 hp range. Kohler, honda, ford, cat, deere, BS, etc. The engines are fairly low cost,light weight and have a high mtbf. Most have peak power at the 2200-3000 rpm range and could be direct drive. Some of the engines are small enough that it seems that if you could take through clutches or one way gears and combine the power of two engines to a single prop it would also provide some redundancy if one engine were to develop problems.

 

I'm not suggesting to throw lawnmower engines into a cozy but engines that are designed for long term mid range use. Seems that most of the issues/failures and costs are associated with complex engine setups that are in a lot of cases unproven and untested.

 

Just curious as to what the thoughts are about my ramblings.

 

Thanks,

 

Hoog

Hoog,

the root of your reasoning is sound, as the future of aviation is in diesels. You seem to forget, however, that the recommended engine for a Cozy is the O or IO-360 Lycoming with about 180 HP. You would need to put together quite a few of your 30 HP diesels to make it work.

What I'm planning to do, is use one of the new V6 turbodiesels currently being used in most modern cars in Europe,

like the VW 3.0 liters V6, or the Mercedes Benz 3.0 liters V6, etc.

In stock form they put out 225 HP at about 4000 RPM. Slightly derated to 205 HP at 2800 RPM they would both make superb aircraft engines.

Keep thinking outside the envelope, that's what experimental aviation is for.

Kumaros

It's all Greek to me

Hi

The RMT Bateleur looks very interesting.

There web site dosnt give you mutch on info or photos.

Hi John,

as stated at their site, the Bateleur was test-flown by the German "Flieger Magazin" and the results published in their January 2002 issue. The main points of the article, positive

+ Light, strong construction

+ STOL, capable of operating out of unimpoved strips

+ Difficult to stall canard configuration

+ Reliabe (but expensive) Rotax 912/914 power

and negative

- Delta Dart derivative, the prototype of which crashed killing the designer

- Very expensive at EUR 68.000 ex VAT at 2002 prices (would be something like USD 100.000). I would very much prefer a RangeR by DAC, EUR 40.000, reliable diesel power, cheap fuel.

I'm still looking, but will probably end up with an Aerocanard, powered by a Mercedes Benz 3 liters V6 turbodiesel.

With friendly greetings

Kumaros

I am not sure if it is in a wrong place. I assume that it has

something to do with its very slow stall speed of 65 km/h.

If you look the side picture what it reminds the most?

To me it looks distantly like giant fowler flaps. Unlike other

canards, Bateleur is STOL (short takeoff and landing) aircraft

and can be operated from unimproved airfields unlike other canards.

It is still very fast to be a microlight (or Finnish term class B ultralight) and

it is also lightweight if compared to other alternatives such as TL-96 Star

which is near to the upper limit of the allowable weight in Finland.

 

Hi Karoliina,

I wish you a happy and prosperous New year.

The Bateleur aircraft is very interesting. I remember coming upon it on the internet some years ago, when operations were still based in South Africa. Your recent post in another thread renewed my interest and I went to the new German site. Then I ordered a back issue of Flieger Magazin (January 2002) to find out more, and now I have mixed feelings about this aircraft.

The gist of it is:

On the positive side:

- Strong, light construction

- Reliable 4-stroke, Rotax power

- STOL, capable of operating from unimproved fields

- Quick to build from a kit

On the negative side:

- It is supposed to be a derivative of the Delta Dart, the prototype of which crashed, killing the designer

- Very expensive for my pocket, more than EUR 68.000 ex VAT at 2002 prices

 

Anyway, the ideal aircraft for me would be a blend of one of the Rutan designs with IBIS and Bateleur and Range-R. This means canard, STOL, diesel power. Until such an aircraft becomes available, I'll order the Aerocanard plans and start building, planning on fitting a 3 liter V6 turbodiesel.

 

Kumaros

It's all Greek to me

I made a slight adjustment to the main page's forums layout since my prior post here so that most recent posts are shown on the top level. This now provides the 30,000 foot view, allowing you to drill into sub-forums of interest.

 

Unless there are any violent objections, I'd like to continue with this layout. I find it to be much more useful than the mass of detail that was previously presented.

No objection from me. I like this layout very much.