[gabedude]

Originally Posted by rjacobs

Your father in law is an idiot or you mis understood him. A turbo prop is a turbine(jet) engine, it does not have pistons or a block.

He's not an idiot, he has a masters degree.

Well, I said turbo-prop (although I do not know what determines a turbo prop vs a conventional engine plane). Whatever engine that has pistons, has a turbocharger (used to be called superchargers), they all had aluminum blocks and ductile iron sleeves. The WW2 plans did. Of course planes engines are put under much more stress than a car engine.

[rjacobs]

I have a masters degree and I am still an idiot so having a masters doesnt mean you are not an idiot.

A turbo prop aircraft has a turbine engine. Alot of aircraft use horizontally opposed turbo charged piston engines and they are aluminum with iron sleeves, but the engines are way different than our engines. They have a crank case and all it houses are the crank and the camshaft. Then they have cylinder jugs that attach to the crank case. They are actually very similar to harley V-twin motors with external push rods and seperate cylinder jugs. Its an old ass design, but why fix what aint broke, ya know. Also the turbo works way differently too, most are a turbo normalizer where the turbo creates more and more boost the higher you go so the engine thinks it is still at sea level. Aircraft engines are not turbo charged to give a performance boost like our engines are.

[Neanderthal Racing]

our motor IS an aircraft engine.

this is just one of many manufacturers using them.
Home

[rjacobs]

It didnt start out as an aircraft engine, that is a kit for homebuilts. I dont think it would last to long running at 5k+ rpm for hours on end unless it was built extremely well. When you use our engines(or any automotive engine) in aircraft you have to gear them(2:1 is pretty common) so that the prop doesnt exceed somewhere around 2500 rpm. If your prop exceeds around 2500 RPM the tips will break mach, that is very very bad. True aircraft engines have very large displacement so that they make power down at low RPM. 360 cid 4 cylinder, 540 cid 6 cylinder, 720 cid 8 cylinder are the typical sizes.

[Neanderthal Racing]

Originally Posted by rjacobs

It didnt start out as an aircraft engine, that is a kit for homebuilts.

so what?
Subaru

Originally Posted by rjacobs

When you use our engines(or any automotive engine) in aircraft you have to gear them(2:1 is pretty common) so that the prop doesnt exceed somewhere around 2500 rpm. If your prop exceeds around 2500 RPM the tips will break mach

same reason the top speed of a helicopter is limited.

[rjacobs]

Where in your link does it say that subaru first built horizontally opposed engines for aircraft? It does say they used a lycoming O-320(a real aircraft engine) in one of their aircraft. FHI built aircraft during WW2 and later, but horizontally opposed engines for aircraft, I dont see it in that link. That link is about using subaru auto engines in airplanes.

[Neanderthal Racing]

Originally Posted by rjacobs

Where in your link does it say that subaru first built horizontally opposed engines for aircraft? It does say they used a lycoming O-320(a real aircraft engine) in one of their aircraft. FHI built aircraft during WW2 and later, but horizontally opposed engines for aircraft, I dont see it in that link. That link is about using subaru auto engines in airplanes.

what the hell are you arguing about? how did you extract i was claiming "subaru first built horizontally opposed engines for aircraft" out of my original statement "our motor IS an aircraft engine"?

are you so anal that i need to say, "our motor is used in homebuilt aircraft applications"? don't bother answering.

[gabedude]

Originally Posted by rjacobs

I have a masters degree and I am still an idiot so having a masters doesnt mean you are not an idiot.

I know you don't have a master's degree, you are a pilot.

Anyway, the point is that ductile iron sleeves would have been great if Subaru would have designed it this way. The STI would eat up EVOs in the mod world period if Subaru would have built their engines high HP modding in mind.

I have done extensive research now into what "safe" HP levels, safe being as in you beat the hell out of the car, you need to build for. 400 WHP with drop in pistons is about the limit.

Sleeve the block and you no longer have to worry about holding 700 WHP in your block, you have to worry about breakin axles or your tranny.

Gabe

[Neanderthal Racing]

Originally Posted by gabedude

Sleeve the block and you no longer have to worry about holding 700 WHP in your block

sometimes you have to worry about the sleeves themselves. there are no guarantees on anything, especially built blocks under big power builds. no one has learned that lesson better than i.

[rjacobs]

Originally Posted by Neanderthal Racing

same reason the top speed of a helicopter is limited.

The top speed of a helicopter is limited based on a concept known as retreating blade stall. The helicopter is moving forward through the air at a speed that becomes equal to the blade that is retreating causing the retreating blade to not be able to move any air . Helicopters are limited by this, not by blades breaking mach. helicopter rotor's usually rotate at about 300 rpm's.

Originally Posted by gabedude

I know you don't have a master's degree, you are a pilot.

I have a M.S. in Safety. I can dig it out if you want to see it.

[tess]

My father deigns the kind of stuff you fly around in Bobby I think he is knowledgeable on the subject. He started his career at Tracor now BAE Systems. If you wish to look at the link below you will see that flight controls and engine controls are part of their product range among other avionics. Anyhow that's my .02.

BAE Systems Inc. - Wikipedia, the free encyclopedia.

tess

[Neanderthal Racing]

Originally Posted by rjacobs

The top speed of a helicopter is limited based on a concept known as retreating blade stall. The helicopter is moving forward through the air at a speed that becomes equal to the blade that is retreating causing the retreating blade to not be able to move any air . Helicopters are limited by this, not by blades breaking mach.

i'll take the hit for not being more clear.

Originally Posted by rjacobs

helicopter rotor's usually rotate at about 300 rpm's.

it may be rotating at 300 rpms but what what is the speed at the tips? what's the effect of tip speed on how it flies? wake me up when youre done.

Originally Posted by rjacobs

I have a M.S. in Safety. I can dig it out if you want to see it.

i doubt if anybody gives a rat's ass what your credentials are at this point.

[Neanderthal Racing]

wikipedia (i know; i'm a genius)

The single most obvious limitation of the helicopter is its slow speed. There are several reasons why a helicopter cannot fly as fast as a fixed wing aircraft. When the helicopter is at rest, the outer tips of the rotor travel at a speed determined by the length of the blade and the RPM. In a moving helicopter, however, the speed of the blades relative to the air depends on the speed of the helicopter as well as on their rotational velocity. The airspeed of the advancing rotor blade is much higher than that of the helicopter itself. It is possible for this blade to exceed the speed of sound, and thus produce vastly increased drag and vibration. See Wave drag.
Because the advancing blade has higher airspeed than the retreating blade and generates a dissymmetry of lift, rotor blades are designed to "flap" – lift and twist in such a way that the advancing blade flaps up and develops a smaller angle of attack. Conversely, the retreating blade flaps down, develops a higher angle of attack, and generates more lift. At high speeds, the force on the rotors is such that they "flap" excessively and the retreating blade can reach too high an angle and stall. For this reason, the maximum safe forward speed of a helicopter is given a design rating called VNE, Velocity, Never Exceed.

[howboutthemapplz]

moral of the story = Bruce pwns n00bs.

[Turbineguy]

In a Blackhawk I run out of power before I run out of airspeed. VNE is 193kts. In the Huey I run out of airspeed before I run out of power. VNE is 123kts. Thats the difference between a fully articulated rotor system and a hingless teetering rigid rotor system. As a helicopter pilot I must agree with both sides that retreating blade stall is an issue as well as VNE causing supersonic tip speeds. However retreating blade stall is nearly always encountered first. The nice thing is that it's a self correcting issue to a point. It causes the helicopter to pitch up and roll left. This has the effect of reducing your airspeed and the issue then is corrected. Sometimes the onset can be felt with the aircraft porpoising and rolling slightly. The other side of the coin is caused by stoopit or careless pilots who try to exceed placard limits for fun or who don't pay attention to airspeed in a dive. The way this happens without retreating blade stall is like this. When there's pitch applied to the blades the velocity over the top is higher to create lift. However when the pilot is in a dive or other low power setting maneuver the blades are at a flatter pitch delaying the onset of any flow separation over the top due to lower airflow velocity. On alot of helicopters the outer 1/3 of the blade if not the whole thing is a symetrical airfoil so at flat pitch the lift goes to about zero. So when you hit the critical velocity where a shockwave is formed at the tip it's very violent and destructive for an airfoil that wasn't designed for that type of airflow and drag to be placed on it. Now picture this blade going from zero airspeed to supersonic and back again several hundred times a minute. Bad.

Now can we get back to talking about pistons and rods?