suprarich said:
LOL
kwnate said:
That is a personal question and I will not answer that
:biglaugh: ...
What do you think about Eagle Rods
- Thread starter oscarsupra
- Start date
LOL
That is a personal question and I will not answer that
:biglaugh: ...
How do you figure the weight of the piston and rod won't make a difference on how fast the engine revs?
You have to overcome the inertia of the piston and rod, when changing the direction of acceleration as it moves up and down the cylinder, do you not?
Duane: :rofl: :biglaugh:
You have to overcome the inertia of the piston and rod, when changing the direction of acceleration as it moves up and down the cylinder, do you not?
Duane: :rofl: :biglaugh:
Doward said:
Moment of inertia and leverage. Stroke affects both. The more critical area to shave weight off is the rotating assembly. The rod weight becomes almost irrelevant once 30 pounds of crank mass (not counting Flywheel AND dampner) start spinning. The rods job, to keep the piston from going into high orbit or attempt to burrow itself halfway to the middle of earths core. Period.
speaking of weight. I see everyone talking about lightweight rods. How many of you folks have actually knife edged and then put the crank on a healthy diet? Run crank scrapers and windage tray?
I am going to be quite frank, IJ said it nicely. I won't. The mind is one very very powerful tool at convincing people of what is not thier. Hell there is more power to regain in windage loss decreases and oil scavenging then there will ever be on lightweight rods.
ok, some corrections from the last page.
If you wanna get technical, no, the rod doesn't load the crank, the rod loads the oil and the oil loads the crank, but the weight (not mass, very different things) of the rod IS applying a force against the crank. and if the rod DIDN'T apply a load to the crank, the car wouldn't move.
Titanium isn't always ideal. the beauty of steel (and SOME Titanium alloys) is that they have a minimum fatigue strength. as a little thought experiment, imagine you've got a pop can in your hands, and you twist/squish it (like what I'm sure you did when you where a kid on the playground to show the others what a badass you where) and then you pull it back apart and untwist it. repeat this maybe 2-3 times and the thing will come apart in your hands. Because aluminum (and indeed 99% of all materials) doesn't have a minimum fatigue strength, as it is stretched and compressed and loaded, it loses strength every cycle, a pop can is an extreme example that will come apart in only a few cycles, but MANY titanium alloys will do this same thing. There's a few Titanium alloys (particularly ones with a high concentration on vanadium, around 3% or greater if my memory is working) that behave like steel in that they will only get so weak, nomatter how many times you stress them.
This principle is why Cubans are still driving cars made in the 50's, steel components have an infinite life cycle if designed correctly and not loaded beyond that design. With most titanium alloys, you don't get that. With aluminum you certainly don't. This is also the reason that every component on an aircraft has a life cycle. It can only be loaded so many times before it weakens to a point less than the design requires, therefor they have a service interval at which they must be replaced. This goes for everything from an airframe to a bolt.
If you wanna get technical, no, the rod doesn't load the crank, the rod loads the oil and the oil loads the crank, but the weight (not mass, very different things) of the rod IS applying a force against the crank. and if the rod DIDN'T apply a load to the crank, the car wouldn't move.
Titanium isn't always ideal. the beauty of steel (and SOME Titanium alloys) is that they have a minimum fatigue strength. as a little thought experiment, imagine you've got a pop can in your hands, and you twist/squish it (like what I'm sure you did when you where a kid on the playground to show the others what a badass you where) and then you pull it back apart and untwist it. repeat this maybe 2-3 times and the thing will come apart in your hands. Because aluminum (and indeed 99% of all materials) doesn't have a minimum fatigue strength, as it is stretched and compressed and loaded, it loses strength every cycle, a pop can is an extreme example that will come apart in only a few cycles, but MANY titanium alloys will do this same thing. There's a few Titanium alloys (particularly ones with a high concentration on vanadium, around 3% or greater if my memory is working) that behave like steel in that they will only get so weak, nomatter how many times you stress them.
This principle is why Cubans are still driving cars made in the 50's, steel components have an infinite life cycle if designed correctly and not loaded beyond that design. With most titanium alloys, you don't get that. With aluminum you certainly don't. This is also the reason that every component on an aircraft has a life cycle. It can only be loaded so many times before it weakens to a point less than the design requires, therefor they have a service interval at which they must be replaced. This goes for everything from an airframe to a bolt.
figgie, I agree 100%
altho the conrods ARE adding a force, the force they're adding will be <1% of the total inertia of the rotating assembly. lightweight camshafts would get you further.
The ass dyno is not a scientific tool.
altho the conrods ARE adding a force, the force they're adding will be <1% of the total inertia of the rotating assembly. lightweight camshafts would get you further.
The ass dyno is not a scientific tool.
Junior said:
Really? What is the max life cycle on a Cessna, or a Piper airframe? A wingspar? because I've never heard of either being replaced because it reached a certain age or time in service.
supraguy@aol said:
you best check the service manual again.
After every 100 hours requires inspection and replacement if needed.
After 1000 hours. The plane must undergo extensive maintanance. Especially of critical systems (Structural, engine etc)
Cessna and Piper pilots not doing them? Well there is a reason you see them plastered all over the news due to mechanical failure, ran out of fuel etc. FAA does not enforce maintanance record on them as strictly as commercial airlines.
<--- Ex Air Force. Maintanance and Depot Maintanance was engrained in me.
figgie said:you best check the service manual again.
After every 100 hours requires inspection and replacement if needed.
After 1000 hours. The plane must undergo extensive maintanance. Especially of critical systems (Structural, engine etc)
Cessna and Piper pilots not doing them? Well there is a reason you see them plastered all over the news due to mechanical failure, ran out of fuel etc. FAA does not enforce maintanance record on them as strictly as commercial airlines.
<--- Ex Air Force. Maintanance and Depot Maintanance was engrained in me.
YOU best check the service manuals.
100 hr inspections are ONLY required if the aircraft is used for hire. There is NO such thing as a 1000 hr inspection. If you are referring to an annual inspection that is done as implied, once a year. Do you know what the difference is between the two inspections? NOTHING. They are the same exact inspection, of ALL aircraft systems. The only difference in fact, is the signature of the inspector.
The reason we see Cessnas and Pipers plastered all over the news is not mechanical failures, but rather pilot error, most often, a loss of spacial orientation. As for fuel starvation, that sometimes happens too, but what does that have to do with aluminum? Aircraft do not need to have components replaced due to service life or time in service, at least not in fixed wing. As for military, that may be different, but if so, how is it that 50 year old B52's were still in service?
I agree with you that parts need to be replaced "if needed". That means if they fail inspection, not if they have too many birthdays.
<< 5yrs teaching, 2600hrs total time; it's engrained in me too.
mustangman05 said:
Why? This thread has some useful info here and it would be nice for someone to search this one day and have it! > Not, a bunch of bickering about airplane maintenance
Duane
I've started a thread in off-topic lounge on this important topic of airplane maintenance... :biglaugh:
http://www.supramania.com/forums/showthread.php?p=695776
http://www.supramania.com/forums/showthread.php?p=695776
figgie said:
Certainly not disputing that - you can remove a lot more weight from the crank than you can the rods
The gains from removing weight in the reciprocating assembly (rods and pistons) are not nearly what you can gain elsewhere - but gain is gain. I take it where I can get it
couldn't speak for the replacement intervals on lightweight hobby aircraft. But I CAN say that they don't get to break the laws of physics and metal fatigue. Neither does anybody making conrods, nomatter how italian or cool they are.
