Cox Engines Forum
You are not logged in! Please login or register.

Logged in members see NO ADVERTISEMENTS!


Prototype MKII Cox_ba12




Prototype MKII Pixel

Log in

I forgot my password

Search
 
 

Display results as :
 


Rechercher Advanced Search

Latest topics
» 50 weight cadtor
by cstatman Today at 8:50 pm

» The Q-Tee Gets Ready for Another Set of Flights
by Ken Cook Today at 5:55 pm

» Save 10% on CEF Shirts and Mugs
by Admin Today at 4:29 pm

» PT-19 3D printing
by howardhb Today at 1:25 pm

» Testors Silver Wind...........
by rsv1cox Today at 12:45 pm

» Mecoa Cox pt19
by roddie Today at 12:39 pm

» ebay Beechcraft Staggerwing project arrives today
by rsv1cox Today at 12:30 pm

» Two Roy Cox Thimble Drome Tether Cars with engines
by rc_fun1 Today at 10:47 am

» Remember the Micro Stick from about 10 years ago?
by dondaniels59 Sun Feb 25, 2024 7:30 pm

» Super Bee 049
by Oldenginerod Sun Feb 25, 2024 4:02 pm

» A song by Roddie
by HalfaDave Sun Feb 25, 2024 10:33 am

» Flying lines and length
by Ken Cook Sun Feb 25, 2024 8:07 am

Cox Engine of The Month
February-2024
1/2A Nut's

"RC Speed Boat Power Drive TD .020"

More info on this engine!




PAST WINNERS
CEF Traveling Engine

Win This Engine!
Gallery


Prototype MKII Empty
Live on Patrol


Prototype MKII

Go down

Prototype MKII Empty Prototype MKII

Post  batjac Mon Feb 13, 2023 12:32 am

Normally, when I get one of my silly ideas I will throw together a quick proof of concept of whatever it was I had thought up.  Once I prove my idea works, I usually just throw it on the shelf and move on to the next hair-brained idea that I thought up in the shower.

However, when I took my inline twin proof-of-concept out to the field to test fly it, one of the club members went gaga over it.  That was about six months ago, and he can’t stop talking about it.  So, since I was building seven Skyray kits for the club fly-in, I figured I’d build a second prototype, trying out some new ideas, and put it on a plane for him.

Since the first inline was built using a hen’s tooth Avion reed valve assembly that I’ll probably never find again, I knew I’d have to find a way to make it with parts I have on hand.  So, I started with a 290 engine with the red postage stamp backplate.  First, since it has the same piston/cylinder/crankcase as a Black Widow, b) since it would be the easiest to modify, and 3: because it has a fine needle valve so I could use a bladder with it, as the club member also wants to try a bladder fuel system.  I started with the beat up backplate, and cut away the housing until there was just a thin wall to sandwich between cases.  


Prototype MKII 20230212-231743
Prototype MKII 20230124-185239
Prototype MKII 20230124-185314


The first test case used a Carl Goldberg postage stamp mount, but I wanted to see if I could cut down on the length, so I got a piece of 1/8” aluminum to use for a backplate.  I also wanted to try something on the air intake.  The normal tanked Bee backplate has that slot on the bottom outside for air to get to the screened intake.  I thought I’d do the same, but not on the bottom where it is most likely to get dirt sucked up.  I figured the cleanest area to suck air would be to the inside of the circle.  I also wanted to be able to mount this in the normal mounting holes for a tanked Bee engine, so that’s what I used for the dimensions.

Prototype MKII 20230207-131640


After marking it all off, I used a Dremel tool, hand drill, and needle files to make the backplate.  As you can see, a couple of the holes are not drilled too accurate.  I really need to set up my work bench so I can use my drill press and scroll saw.

Prototype MKII 20230212-145728



After measuring the assembly front to back, it worked out that a 1” countersunk 2-56 machine screw would hold everything together.  A quick trip to Ace Hardware for 8 screws (so I could backfit my first test) and it was time to put it all together.

Prototype MKII 20230212-150012


A good clean and oiling and it all went together with a new crankcase gasket and  mylar reed.

Prototype MKII 20230211-200732
Prototype MKII 20230211-200833
Prototype MKII 20230211-200956


And mounted on the Skyray that I built for it.


Prototype MKII 20230212-160422
Prototype MKII 20230212-160434



The only thing left is to test run it to see where the needle setting needs to be before I can complete the engine.  I’m going to take it out to the field tomorrow and see if I can get it running.  And to show it to the club member and let him go nuts over his own Cox twin engine.

The Repeat Mark
batjac
batjac
Diamond Member
Diamond Member

2022 Supporter

2023 Supporter

Posts : 2327
Join date : 2013-05-22
Age : 60
Location : Broken Arrow, OK, USA

Back to top Go down

Prototype MKII Empty Re: Prototype MKII

Post  Levent Suberk Mon Feb 13, 2023 12:49 am

Hi, I don't see postimages pictures any, why I don't know. I use Android system.

Prototype MKII Scree129
avatar
Levent Suberk
Diamond Member
Diamond Member

Posts : 2191
Join date : 2017-12-24
Location : Türkiye

Back to top Go down

Prototype MKII Empty Re: Prototype MKII

Post  Levent Suberk Mon Feb 13, 2023 1:04 am

However they can be seen on first page, but no pictures seen in thread.

Prototype MKII Scree131
avatar
Levent Suberk
Diamond Member
Diamond Member

Posts : 2191
Join date : 2017-12-24
Location : Türkiye

Back to top Go down

Prototype MKII Empty Re: Prototype MKII

Post  rsv1cox Mon Feb 13, 2023 10:47 am

Mark, on your prototype I see a needle valve but don't see a NVA. I also don't see a fuel tank or extended crankshaft? Is the back engine just along for the ride? Answers must be in your text but I can't read/find it.

I always wanted to see the internals on these made-up multiples.
rsv1cox
rsv1cox
Top Poster
Top Poster

2022 Supporter

2023 Supporter

Posts : 10339
Join date : 2014-08-18
Location : West Virginia

Back to top Go down

Prototype MKII Empty Re: Prototype MKII

Post  GallopingGhostler Mon Feb 13, 2023 11:27 am

I gather that Mark's model is made to look like a twin, but the rear cylinder is not active. Huh...

The red between is a cut down postage stamp back. Very Happy lol!
GallopingGhostler
GallopingGhostler
Top Poster
Top Poster

2023 Supporter

Posts : 5131
Join date : 2013-07-13
Age : 69

Back to top Go down

Prototype MKII Empty Re: Prototype MKII

Post  rsv1cox Mon Feb 13, 2023 11:46 am

GallopingGhostler wrote:I gather that Mark's model is made to look like a twin, but the rear cylinder is not active. Huh...

The red between is a cut down postage stamp back. Very Happy lol!

There just isn't enough space in there for a NVA.  It must be coming up through the back engine and you remove the glow head or cylinder to access it.............. Huh...

Or.....or drill a hole in the bottom of the rear engines case.

Inquiring minds want to know. Smile

So now you need fuel line.

The unfinished ---  Bob

Edit add...........So now I gotta make one.  Put the RX-7 on hold for a year or two while I figure this out................

Edit add...Ok first make a spacer to increase the gap between the two so you don't have to trim the head and fins...........more to come......or maybe not
rsv1cox
rsv1cox
Top Poster
Top Poster

2022 Supporter

2023 Supporter

Posts : 10339
Join date : 2014-08-18
Location : West Virginia

Back to top Go down

Prototype MKII Empty Re: Prototype MKII

Post  GallopingGhostler Mon Feb 13, 2023 12:23 pm

I bet Mark used the rear cylinder passageway to pass the needle (use a dead glow head with threads removed as needle knob) Wink and fuel line opposite through a drilled holed at the bottom of the rear crankcase. Huh... Very Happy

What say ye, Suspense Thriller Mark? Smile This Site Rocks!
GallopingGhostler
GallopingGhostler
Top Poster
Top Poster

2023 Supporter

Posts : 5131
Join date : 2013-07-13
Age : 69

Back to top Go down

Prototype MKII Empty Re: Prototype MKII

Post  batjac Mon Feb 13, 2023 11:05 pm

The method I used to make this is explained in this thread:  https://www.coxengineforum.com/t14510-here-hold-my-beer


I just made a few changes that occurred to me.  If I build a third one, I might find some high heat plastic to make the backplate instead of aluminum.  I flew this today, and it flew okay, doing loops/eights/inverted.  I think it got four flights.  But I need to do some tweaking.  I think the 18% fuel I used today might be bad.  I tried the fuel in three planes today and none of them needled well.  I think I'll just make up a new batch of 30% and see if that helps. I'm also going to try a few different props to see what it likes.

The Mark Too Mark
batjac
batjac
Diamond Member
Diamond Member

2022 Supporter

2023 Supporter

Posts : 2327
Join date : 2013-05-22
Age : 60
Location : Broken Arrow, OK, USA

Back to top Go down

Prototype MKII Empty Re: Prototype MKII

Post  getback Tue Feb 14, 2023 6:22 am

If you only had a crankshaft made for two Wink  If the twin part work you could see them for $400 on the Bay Computer Issues  But I do like the hidden needle valve and give a good appearance of a twin And it RUNS !!  Beers Clapping At least he says it does Hint Hint lol!
getback
getback
Top Poster
Top Poster

2022 Supporter

2023 Supporter

Posts : 9960
Join date : 2013-01-18
Age : 66
Location : julian , NC

Back to top Go down

Prototype MKII Empty Re: Prototype MKII

Post  rsv1cox Tue Feb 14, 2023 6:47 am

batjac wrote:The method I used to make this is explained in this thread:  https://www.coxengineforum.com/t14510-here-hold-my-beer


I just made a few changes that occurred to me.  If I build a third one, I might find some high heat plastic to make the backplate instead of aluminum.  I flew this today, and it flew okay, doing loops/eights/inverted.  I think it got four flights.  But I need to do some tweaking.  I think the 18% fuel I used today might be bad.  I tried the fuel in three planes today and none of them needled well.  I think I'll just make up a new batch of 30% and see if that helps.  I'm also going to try a few different props to see what it likes.

The Mark Too Mark

"It looked more like a faux pas than a faux twin. " Good line Mark!

Looked up your explaining thread. Two years + ago, my memory only goes back a fraction of that, but I should have as I responded at least seven times. Saved it this time. I have got to make one. Imitation is the sincerest form.........
rsv1cox
rsv1cox
Top Poster
Top Poster

2022 Supporter

2023 Supporter

Posts : 10339
Join date : 2014-08-18
Location : West Virginia

Back to top Go down

Prototype MKII Empty Re: Prototype MKII

Post  getback Tue Feb 14, 2023 9:43 am

I can't believe its been 2 yrs. I remember the thread but had not Idea been that Long Old Bugger Old Bugger
getback
getback
Top Poster
Top Poster

2022 Supporter

2023 Supporter

Posts : 9960
Join date : 2013-01-18
Age : 66
Location : julian , NC

Back to top Go down

Prototype MKII Empty Re: Prototype MKII

Post  GallopingGhostler Tue Feb 14, 2023 10:08 am

getback wrote:I can't believe its been 2 yrs. I remember the thread but had not Idea been that Long Old Bugger Old Bugger
Most Amazing Eric Wink , welcome to the club. Old Bugger Do you know what they say? Huh...
How many seniors does it take to screw in a light bulb?
Only one, but it might take him all day.
Laughing
GallopingGhostler
GallopingGhostler
Top Poster
Top Poster

2023 Supporter

Posts : 5131
Join date : 2013-07-13
Age : 69

Back to top Go down

Prototype MKII Empty Re: Prototype MKII

Post  Sponsored content


Sponsored content


Back to top Go down

Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum