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» **VOTE-ON-THE-NEXT-COX-ENGINE-OF-THE-MONTH** (July 2018)
by balogh Yesterday at 11:51 am

Cox Engine of The Month
June-2018
Davenz13's

".049 Bee"



PAST WINNERS
Speed Contest 2018
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World of Aviation

Recent engine acquisitions

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Re: Recent engine acquisitions

Post  1/2A Nut on Thu Nov 30, 2017 9:23 am

Thank you, I bench tested with the standard plastic back plate I want to try something like this next.

Pressure tap idea working on it..

It can also just be mounted to the fire wall and the stem is
cut to butt up against the fire wall and be blocked off from
air intake keeping the reed closed. Of course you could just fill
the stem up with JB weld.



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Last edited by 1/2A Nut on Thu Nov 30, 2017 2:40 pm; edited 2 times in total
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Re: Recent engine acquisitions

Post  MauricioB on Thu Nov 30, 2017 9:31 am

Interesting !, in the way you show in the photo, you would be pressurizing (sending pressure) to the fuel tank, which would allow you to have a constant flow of fuel! .... It's a good idea, you have to see what happens in the practice!
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Re: Recent engine acquisitions

Post  balogh on Thu Nov 30, 2017 9:37 am

1/2A Nut wrote:Thank you, I bench tested with the standard plastic back plate I want to try something like this next.

Reed for a one way valve controlled pressure tap. :brows.

It can also just be mounted to the fire wall and the stem is
cut to butt up against the fire wall and be blocked off from
air intake keeping the reed closed. Of course you could just fill
the stem up with JB weld.



Thumbs Up






Brad,

an interesting combination, but with the reed valve closing when the crankcase is pressurized, how will you pressurize the plastic tank through the venturi?


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Re: Recent engine acquisitions

Post  1/2A Nut on Thu Nov 30, 2017 2:25 pm

I spoke too soon after thinking about it, the reed will not regulate pressure.
Piston goes down is when the reed would need to be open and that is not
going to happen.

Can fill the void with JB weld with a very thin oiled steel wire centered when filling it up.
After 65% cure time slide the wire out for the pressure vent. I plan to use a guitar string
the lower light gauge steel E string (.3M). Hope to improve fuel flow when pulling straight
up out of a down wind passes and hard turns.

The fire wall with have a ply ring  that protrudes into the back plate cavity so the engine gets
more bite with the back plate mounting screws. The TD .020 will be screaming much more thirsty
may go with 3/4oz tank.
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Re: Recent engine acquisitions

Post  1/2A Nut on Thu Nov 30, 2017 7:33 pm

Ok the solution was easy using some small oil spray extension tube made from hard
plastic worked, the hole in the tube is .35mm. I used 20mm length of it to extend
the pressure flow restriction. The throttle sleeve will reduce pressure at idle which  
should help it from going rich, full throttle NV setting should be interesting to see if
the engine picks up some more rpm over that last test. OD of the red tube is 2.1mm.




Can use this one with no pressure tap about the same weight.



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Re: Recent engine acquisitions

Post  Jason_WI on Mon Jan 01, 2018 6:26 pm

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Re: Recent engine acquisitions

Post  dckrsn on Mon Jan 01, 2018 8:18 pm

Jason_WI wrote:Blind squirrel found a nut in the woods.
https://www.rcgroups.com/forums/showthread.php?3011680-Vintage-Nitro-Engines
Nice"nut", Jason. Good way to
start the new year. Clapping
Bob
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Re: Recent engine acquisitions

Post  Oldenginerod on Tue Jan 02, 2018 3:39 am

Great pick up. Lots of potential there Thumbs Up
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Re: Recent engine acquisitions

Post  Marleysky on Tue Jan 02, 2018 8:56 am

Yeow! You’re starting the New Year on the right foot! I see a bit of cleaning and polishing in your future! Nice find for sure!

Fireworks
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Re: Recent engine acquisitions

Post  Surfer_kris on Tue Jan 02, 2018 2:41 pm

Here is my latest purchase, an un-used TT .25 engine for about $25. Smile
I have another one that's a real sweet runner, and these are very lightweight for their engine size too.

I'm really glad that I checked the inside before running it though. It turns out that it needed a bit of "de-burring" inside the crank... affraid





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Re: Recent engine acquisitions

Post  KariFS on Fri Jan 12, 2018 8:39 am

Kris, What the...? Is that left from the machining of the induction channel or has there been a reduction bushing or something inside the crankshaft?

Here is my very latest acquisition. No motor on it but still somewhat related. A few weeks (or months) ago I answered a poll about our hobby and won this:



It is the "ELF" by Vladimir's Model in Ukraine. Wingspan is 39in, flying weight 3.35oz. It is called a DLG, which means "Discus Launch Glider". A sort of a hook is installed on the left wingtip and the plane is launched like a discus. Plenty of videos on the 'tube.

It is handcrafted, materials are a bit exotic to me. Carbon fibre wing structure, thin plastic radio compartment and the tailfeathers look like they are 3D printed.



I'll need to get some very small servos, a micro receiver and a 1S LiPo receiver battery. Probably need to move on to GHz technology, I doubt there are any receivers available that would be tiny enough and compatible with my existing 35MHz gear.
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Re: Recent engine acquisitions

Post  MauricioB on Fri Jan 12, 2018 8:52 am

Surfer_kris wrote:Here is my latest purchase, an un-used TT .25 engine for about $25. Smile
I have another one that's a real sweet runner, and these are very lightweight for their engine size too.

I'm really glad that I checked the inside before running it though. It turns out that it needed a bit of "de-burring" inside the crank... affraid






Ohh affraid ! I'm surprised, I agree with KariFS will be a reduction bushing? ... I'll grotesque that piece of metal so that it has arrived from the factory like this!
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Re: Recent engine acquisitions

Post  getback on Sun Feb 04, 2018 11:02 pm

Well if you can say just forgot i had this ...


Funny what you find looking for something else Shocked Eyebrows Sure wish i had got those measurements off the other .15 for the throttle assy pieces Rolling Eyes
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Re: Recent engine acquisitions

Post  Surfer_kris on Mon Feb 05, 2018 12:17 am

KariFS wrote:Kris, What the...? Is that left from the machining of the induction channel or has there been a reduction bushing or something inside the crankshaft?

Sorry for the late answer here. The metal is a left over from when they machined the opening in the crank. It seems they first hollowed out the crank and then machined the window, which left a big piece inside the crank. I can understand how this happens during machining but they need to incorporate a reburring step of the bore or at least a visual inspection. As the crank  is hardened after the machining, bits like these can easily ruin an engine if they come off later during regular running.

I have found similar issues in the CS/Brodak MkI engines but this is the worst case I have ever seen...
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Re: Recent engine acquisitions

Post  ThermalSniffer on Mon Feb 05, 2018 2:35 pm

KariFS, beware, the ELF is somewhat of a gateway to a whole new addiction. At least it was for me, then again, by my psuedonym here, you'll probably guess I was a little biased to start. DLG in general is so instantly gratifying and especially so if you can thermal. Even the ELF is very high performance compared to the old gas bags some of us used to fly. I could go on forever about how good DLG is ... Laughing
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Re: Recent engine acquisitions

Post  KariFS on Sat Mar 03, 2018 7:08 am

Hey TS, sorry, missed your reply almost a month ago! It would be nice to hear about your experiences and tips about flying a DLG. Slope soaring and Thermal chasing are fascinating concepts. So far I have just flown my 2 meter Riser, up to the sky with electric power and just gliding back. The area I fly in has no thermals and is relatively flat too. It is by a lake so the "lift" runs downwards there.

I have tried to cut back on buying stuff lately, but got a little carried away one night when I saw a couple of ads at the Cox Facebook group. There was a pile of misc parts, among which I spotted a metal non-vented backplate and an exhaust collector. The same guy also had a bunch of wrenches, a reset tool for .074/.09 engines, new rubber spinners and some engines. I made an offer for a bunch of stuff and this is what I ended up with:



The engines are nothing special, all with #2 cylinders but generally healthy and they also have 128tpi needles. The W type glow head looks like it's toast Crying or Very sad

The black firewall looks like it might be from a PT-19, but what about the red one?

Here is a close-up of some parts that I don't remember seeing before, and would appreciate any insight:



The small clear fuel tank is probably from an RTF plane? What about the tank mount? Cox or aftermarket? The mounting pattern is the same as the one on Bees, and the beam mount fits a Tee Dee. The little discs look like some kind of extra flywheels or nose weights (edit: the yellow one is obviously plastic, most likely a backing plate for a spinner), they fit the .049 prop screw perfectly and also have indentations made for (or by) the pattern on prop drive plates. I am not familiar with Cox or other RTF's but it would be nice to know where these came from. Just curious Smile

I am familiar with the exhaust collector, but is it just an accessory part or was there a model that used this as standard?

The shim is just a little too big and a lot too thick to be a head gasket for a .15, could this be a timing shim? Also the Medallion carb body looks strange, is it just cut for some reason or is there a model that uses this kind of a part?


Last edited by KariFS on Sat Mar 03, 2018 7:26 am; edited 1 time in total
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Re: Recent engine acquisitions

Post  Ken Cook on Sat Mar 03, 2018 7:24 am

Your tank mount in the back is a Norvel for the Big Mig Start up series engines. They made two styles. Works so so, orientated more for the beginner. I found it to be a bit problematic. I also don't like having my engine sticking way out away from the firewall. The brass weight I believe is from Cox Rivets of possibly the AT -6 Texan. The black drive washer is for the older style spring starters. The black being handed one direction and the red for the other hand depending on pusher/puller status. The Cox muffler I have seen on many models usually car types, very restrictive and performance in rpm's drops quite a bit. The red carb body is for the Medallion engine, hard to tell size wise but seeing there's already a package marked Medallion .15, that might be for a .15. Medallions were offered in .049, .09, .15.
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Re: Recent engine acquisitions

Post  KariFS on Sat Mar 03, 2018 9:02 am

Thanks Ken, interesting fact about the Big Mig is that it has the same bolt pattern as the Tee Dee. Is it the same for .049 and .061 Big Migs? I am asking because I am building a small profile stunt plane but it just may be a tad big and/or heavy for Tee Dee. It would be nice to have a possibility to fit a Big Mig instead without any modifications.

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Re: Recent engine acquisitions

Post  balogh on Sat Mar 03, 2018 9:06 am



Last edited by balogh on Sat Mar 03, 2018 9:13 am; edited 1 time in total
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Re: Recent engine acquisitions

Post  balogh on Sat Mar 03, 2018 9:11 am

Kari the bolt pattern of the Big Mig and TeeDee 049 are the same but the crankcase outside dia of the Big Mig is 1.5mm wider so the TD radial mounts are tight for the Russian...
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Re: Recent engine acquisitions

Post  KariFS on Sat Mar 03, 2018 9:33 am

Thanks Andras. My engine mounting point has some extra room, I unintentionelly built it a bit wide... Here's a picture of the model I am working on. It is built around a pair of general-use styro wing elements glued with their bottoms against each other to create a symmetrical profile. I will have difficulties to keep it under 230-250g which seems to be the magic number for .049 stunts. This is not entirely my own design, I have combined parts and dimensions from here&there. The profile is from Yak-55, so the Big Mig would be very appropriate Thumbs Up



You and me both have our (possibly similar) opinions about the Soviet Union and Russia, but I must admit they have created some mighty civilian machinery too!
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Re: Recent engine acquisitions

Post  balogh on Sat Mar 03, 2018 9:39 am

Beautifully made parts Kari, your plane will be a ball to fly.

Unfortunately the NIB Big Mig I bought some years ago only corroborated my life-long bias against Russian machinery I earned while living in the happiest barrack of the Soviet empire until 1989 but I appreciate the different opinion of others here.
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Re: Recent engine acquisitions

Post  MauricioB on Sat Mar 03, 2018 9:47 am

balogh wrote:Beautifully made parts Kari, your plane will be a ball to fly.

Unfortunately the NIB Big Mig I bought some years ago only corroborated my life-long bias against Russian machinery I earned while living in the happiest barrack of the Soviet empire until 1989 but I appreciate the different opinion of others here.

Hello guys, Kari, good job friend, I will follow your progress ... I am also working on some new projects .... soon I will share with you, I do not do it NOW so as not to bore you.
András, could you please give your opinion Norvel experience please, I will read you carefully ....
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Re: Recent engine acquisitions

Post  balogh on Sat Mar 03, 2018 9:56 am

Mauricio my Big Mig experience was devastating, finding practically no compression in a brand new engine sold and shipped by the US distributor who then gave me a non-existing address in (Russian) Saint Petersburg to send my engine for warranty repair....I would not tear up the scar tissue my report then left on the soul of many Norvel fans here...suffice to say I have only flown COX since then except my larger planes powered by OS FS56 alfa 4-strokers
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Re: Recent engine acquisitions

Post  MauricioB on Sat Mar 03, 2018 10:00 am

balogh wrote:Mauricio my Big Mig experience was devastating, finding practically no compression in a brand new engine sold and shipped by the US distributor who then gave me a non-existing address in (Russian) Saint Petersburg to send my engine for warranty repair....I would not tear up the scar tissue my report then left on the soul of many Norvel fans here...suffice to say I have only flown COX since then except my larger planes powered by OS FS56 alfa 4-strokers

You bought it here ?: http://www.nvengines.com/

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Re: Recent engine acquisitions

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