acerc

John M, the biggest problem with the prop sizing is limited choices in wood. I knew as soon as I grabbed hold of it with the 30x14x3 that I should have went with the 30x19x3, and will order one soon. See, these are the types of expenses that are keeping me from getting a new RF.

acerc

Here is a description of where and what on the bats and lead. In the pic the black line is where the 1.2lbs of batteries were, the yellow line is where they are now. The pink line is where the 2lbs of dead lead was, and the blue line is the CG. It's kind of funny, it took 2lbs 1/3 the distance forward of the CG to compensate for 1.2lb 2/3 the distance of CG to the rear.

squirrly

My Feedback: (3)

Robert,
I believe the CG in the Pitts is like a fulcrum. There's a formula for solving it and can be better understood if you Google it. Its been a while...I need to Google it to.


Jeff
By the way I like the pic...nice.

John_M_

Yeah, the 30-19-3 over on vogelsang-aeroscale's site ain't cheap... that will hurt every time you tip a prop, wow not cheap at all... I suspect carbon fiber isn't cheap either, but its a stiffer blade, may give you better performance.... its like anything you have to fine tune, you'll need to get several pitch / dia sizes until you find the ratio that works, but at least you have a good 2 blade prop to fall back on.



John M,

acerc

I am not figuring out the CG, that was done a while back, I am lightening the load by moving the batteries and removing the lead. And, Thanks!

The problem is I am using wood and there is not many choices available. There are a lot more choices in carbon fiber but I don't like how they are made, too cheap and light in my opinion, and I have seen several delaminate in flight.
I have been running a 34x12 but will pick up a 34x14 Monday for a little more giddy-up. In the near future I will get the 30x19x3, I would prefer a 32x16x3 but no one make's it. The wood is a hundred buck's and the carbon is near 200 buck's so the wood is also a little more trial and error friendly. If Solo props were still in business I could get a 3 blade adjustable, but......

squirrly

My Feedback: (3)

Those larger props are expensive! I have a 37% Edge 540. It's bad enough having to replace ones I damage on landing and definitely adds up when experimenting to find a preferred performance. Gets even higher as you search for that in a 3 blade prop. An expensive part of the game...not fun. Also seems that whenever you ask someone who's flying the prop your interested in, he's flying it for a performance that's different than the one your looking for. Never an easy find...

You'll find one Rob, hang in there. Like John said you still have a nice 2 blade that works.

Jeff

John_M_

An adjustable pitch 3 bladed prop would be great for dialing in the right pitch... I've seen some over on TBM's site, but not in a 30" dia, and they are more suited, appearance-wise for the war birds though... I've never heard of a CF prop coming apart, but then again we don't get many 12hp valach 170's over at our field, I'm sure you'll find out real quick how cheaply made a prop is with 12 ponies behind it.

100 - 200 hundred bucks per prop, should teach anyone how to land cleanly... all it takes is the slightest tip strike and you got yourself a paint stirrer; I wouldn't use it again, not with that 170... I've seen what a helicopter blade can do when it separates from its holder, that's why I go stand behind the trees when they start flying the helicopters.


Not sure if you like Xoar props, but they make a 32-16-3

http://www.xoarintl.com/rc-propeller...ade-Propeller/


John M,

Billy J

My Feedback: (4)

Hey Paco send me pics of Eagle what motor? weight ?? m scratching one

acerc

Who is Paco?

acerc

I would have given the Xoar a try but could not find anyone that carries it. The local LHS's would not even order one.

acerc

The gear have been tightened up and the intake tube installed. That will be the last time I do an intake tube after the engine is installed, what a PITA it was.

John_M_

I think you can order it from desert aircraft in Arizona, they carry Xoar, and a few other brands.

http://www.desertaircraft.com

BTW, Paco is a Spanish nickname for Francisco, or the Urban definition is a drunken Mexican.



John M,

acerc

I do my research profoundly, might not remember much of it, but do take notes on things I want to go back to or found.
Don't get me wrong, I appreciate your effort in aiding me find or do things.

acerc

The exhaust is complete other than lock tight on the flange nut but I don't have any with me. Have to go home tomorrow for a day and will pick up some more lock tight. So, for now, I am done. I added a pic just cause I haven't lately.

squirrly

My Feedback: (3)

Robert,
Nice work...I'm hoping between the two( intake tube, 2-1 exhaust) will add a little increase in power/RPM's. Let me know how it works out? Also, change in sound. I like the idea of the the setup but, again it's like one of those experiments trying to find that perfect balance for more rpm's without changing that awesome exhaust sound.

Jeff
Good luck! It was something I thought about also, earlier when installing the motor on the Bulldog.

acerc

I am doing the 2-1 because I have read and was told it gives it just a tad deeper note, and I think it will aid in the smoke. With the split exhaust the smoke comes out separated, I am thinking this will make it appear even thicker. We'll see.

acerc

By the way, that single exhaust outlet is scale to my airframe.

John_M_

Well no I didn't actually look for the 3 blade, but on Xoar's site they list DA as a source to buy; they also list tower hobbies as a dealer, they don't carry the 3 blade either, but I figure DA, or TH could get you what you needed if they didn't actually have it in stock... most companies will only stock what sells, but you can order none stocked items... DA probably could have it dropped shipped to you right from Xoar, or contact Xoar directly and they'll hook you up with either a dealer that carries it, or sell to you direct.


I'm one to beat a dead horse Ace, if they make it has to be available .

***EDIT***

$265 plus shipping for the 32-16-3... I don't know about you but that is a bit spendy for a wooden prop... don't see why the big jump in price from the 32-12-3; 100 bucks more for the 32-16-3

http://www.justmodelprops.com/xoar-p...tor-beechwood/


***EDIT***

The intake extension tube you're referring to, are you talking about the velocity stack?... that should help with your throttle transition, not to mention it will reduce greatly any spit back from the carb venturi / throat,

John M,

John_M_

Nice job on the exhaust Ace; looks more finished than just two pipes sticking out... I like your crankcase breather bottle as well


John M,

squirrly

My Feedback: (3)

I like the idea of dialing down the smoke pump creating/illusion of more smoke with the 2-1 exhaust. Haven't thought of that...good one. I did speak with Gerhard a while back about the 2-1 exhaust and he agreed also of the better sound it produces(win, win ). Also you can never go too scale with that beauty. I've looked up many full scale pics/vids of the Pitts and agree its a true look.

Jeff

John_M_

Ace, out of curiosity, why are you injecting your smoke oil down at the end of the exhaust system... the header pipes will have hotter exhaust gases giving you a better burn off of the smoke oil.


John M,

Jim Branaum

My Feedback: (3)

And thicker smoke

acerc

When I had the exhaust headers off brazing the Y on I noticed just how close to the exhaust exit the oil was actually spraying into. Being a four stroke I think the oil may have been a coolant to the exhaust and maybe even into the head. Remember the conversation of "It sounded as though it lost rpm when activating the smoke"? Maybe injecting it there is not a good idea (on a 4 stroke) so I am going to see if an extra wrap is enough heat to have the same smoke at the further injector distance. If it don't work out it can always be changed back, or closer to it.

John_M_

I don't think its as critical as it is on a 2 stroke, were the burning smoke oil expands and upsets the pressure wave in the exhaust pipe / muffler... usually 2 stokes won't run well at lower RPMS with the smoke on as it upsets the scavenging and fuel transfer due to the expanding smoke creating pressure inside the exhaust system... with a 2 stroke you can inject too much smoke oil and cause the engine to quit... with a 4 stoke it may have more effect on the idle quality, but you would have to block the exhaust to create enough back pressure for the engine to quit.


With a 4 stroke, you have the valve overlap, where the burning / expanding smoke oil will interferer with savaging and the induction cycle, but its a very small window of time / degrees that it occurs... that's why you get the rpm drop with the smoke on, the increase pressure in the exhaust system changes the air/fuel ratio in the cylinder, but as the rpm increases, so the effect on the air fuel ratio diminishes, because the exhaust gas velocity increases, which improves the scavenging effect at the overlap duration... you may still get the rpm drop with the smoke oil injected towards the exhaust tips but the exhaust gases are a lot cooler at the exhaust tips, so you may get less smoke, and more unburned oil thrown out on to the fuselage.

it will be interesting to see how it works out.



John M,

acerc

My version is shorter, "Being a four stroke I think the oil may have been a coolant to the exhaust and maybe even into the head."