Jaspur_x

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Ok guys , as I`m tinkering with throttle designs for my .020`s I noticed that the 3 020`s that I`m tinkering with ( 2 peewee`s and 1 teedee)
The ports on the 3 cylinders are in diferent locations : front to rear , left to right , etc.
All 3 are in diferent orientations , the1 peewee`s are more frontand rear , and the teedee is nearly leftand right , and the second peewee is about half way in between.

Has anybody else ever noticed this?

lildiesel

Just about every Cox engine I've ever seen or owned had slightly different orientation of the exhaust slits in relation to the sides of the crankcase. Somebody with more experience with machine work than turning a few brass candle sticks will know exactly the reason why, but I'd guess it is just the small differences in where the tool starts making the cut between each operation.

ffkiwi

Jared-there is a school of thought that says having the exhaust ports oriented fore and aft rather than at each side is good for a few more rpm. Probably due to better slipstream scavenging in flight.

ChrisM
'ffkiwi'

GrahamC

That might potentially help. Another often touted theory is that having the exhaust slits fore and aft puts the cylinder bypasses on the left and right and makes them more "open" and "flow" better and less blocked by the crank web and back plate. I have been generally following this rule of thumb but I am not certain - I see a lot of 1/2a speed type model designs from the 60's which purposely put the exhaust slits on the left and right in order to, I presume, encourage scavenging of the exhuast from the cowl area of the model.

For general sport use it probably does not make a lot of difference.

cheers, Graham in Ottawa Canada

BMatthews

From what I've seen Cox never cut the threads or took any care to start the threading in a consistent manner on any of their engines other than the .15 TeeDee. My fairly large collection of around 15'ish .049's and around 6'ish .020's have the exhaust ports randomly positioned. And if I move one cylinder between two crankcases the ports will end up at some random position that is different from on case to the other.

Jaspur_x

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ChrisM , I was thinking along those lines , and thought I would see if anyone knew for certain.
One waay or the other it would affect performance in some way.

Forcing more fresh air into any engine always does, even if it blows the fuel charge ( a % of it ) through the ports.

Bmathews , that randomness per engine , but not when swapping into crankcases would imply that the threading ,or bases on the crankcases are the diference , would it not?

Tee Bee

When it comes to cylinder port orientation on my sport planes, I just screw 'em on, fire 'em up, toss 'em in the air, and enjoy. I haven't let that one bog me down yet.

Jaspur_x

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Well , while I wait for my throttle sleeve for the teedee020 to get here , maybe I will throw the .061ame on the littlest stick or the bipe and try my hand at 3-d flying , I know , I know , but I dislike not having a throttle that much , and want to get some flying time in.

controlliner

There is nothing like flying full throttle, kamikazie style. It gets the heart goin'. Throttles are for those who want to relax.

BMatthews

If you understood how threading is done on the old machines you'd realize that the threading on both the cylinders and crankcases is totally random. Unlike today's CNC machining centers the machines never stopped and the feeding was automatic based on when and where the part came to rest in the holding die. It's more random than gambling at Vegas....

skaliwag

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Black 13 works every time @ Stinky's Pleasure and Gambling Palace

Tee Bee

I was in Vegas last week but never saw that place. I think I made that bet a time or two, though.

skaliwag

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Tee Bee... It's across the Strip from Mona's Pleasure and Poker Palace... Where the Slots are always loose.

proptop

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So...that's how you got the name skaliwag...!?

skaliwag

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No Proptop... That's a whole different story.. Got the name back when I was a lad of 17, being the only Englishman working with a crew of Irishmen.
The English definition of Skaliwag is different from the Southern States one.

Jaspur_x

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Controlliner,
That is quie true , of course if you wanna try whiteknuckle flight , c`mon over and chase the cat around the house with my blade msr heli , that`ll get ya puckering lol

Besides , If I wannt get excited or experience a "RUSH" I go get out one of my race quads and tear it up for 10 laps or so , I fly r/c just to relax , thats why I like the throttled engines; full bore all you want , then throttle back and fly relaxedly. Not to mention I perfer to land under power , not wounded tweety tyle lol

BMathews , ok that makes sense to me totally now. I never get done learning in R/C , 30 years and leraning lol

Jaspur_x

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OH , durnit , I forgot to ask in my last post , how much buffer space is usually between a cylinder and the throttle sleeve?
Ithink I will turn out a throttle sleeve ( of sorts) tonight , tired of waiting on shipping to deliver one ( pout pout)

Jaspur_x

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ok , I have heard that throttling a teedee 020 with a crab does not go well at all. I`m not questioning that at all , quite the oposite.

However , I was scrolling through the videos on utube in the related files thing , and there it is , a muffled and throttled teedee020.
I can`t figure out how to track down the source of the video , I want to ask the guy what did he do to get it to run like that?

Now my head has been nyquil swimming for 2 weeks now , sick as a dog. I swear it`s makingme fuzzyand forgetful. And I do not know how topost"links" anyway , butif you go to utube and type in "throttled TD .020 there it is.
Could somebody that knows computers a little bit help me track this guy down? I just want to copy his engine thats all.

Thanks guys,
Jared

skaliwag

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Probably AndyW

Jaspur_x

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Well if it was AndyW I`m not suprised , if anybody could get a teedee to idle it would be him.
I guess I should pm him and ask.

And Skaliwag , does the english version of your screen name have a meaning that you were wagging something? just kidding , working with a bunch of irishmen I`m not certain I want to know what you were wagging. Awwww , c`mon that was a litle bit funny, well , maybe it would have been funny in vegas.

skaliwag

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Wagging a Skali

Jaspur_x

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Ummmm , that may be illegal in some states , and definately do not let a policeman catch you doing that!

I did that once when I was little , at the beach , my mommy yelled at me...

skaliwag

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She must be Irish

proptop

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The way I heard it while growing up means rascal or scamp, or brat...a "wise *****" sort of person...but after doing a yahoo search, I see some other less than complimentary definitions...[X(]

I didn't mean anything negative by it skaliwag...my mom called me that a few times when I was a kid...when I was acting-up.

Tee Bee

Oh my did this thread take a turn!............I love it. "She must be Irish" Best laugh in days.