GrahamC

Just finished assembling a cox 049 reedy for 1/2a Texaco. The weather was nice but the fields are getting too wet, soft and messy for flying so it was a good day to run some tests. The first test runs went very well and I just had to share.

This engine was assembled from stock Cox parts except for the spinner and spinner drive washer and is destined for use in a Playboy with a 50 inch wingspan for 1/2a Texaco. US rules are different than those used in Canada. We have fewer engine restrictions than in the US.

Babe Bee back plate with screen removed,
5.1 CC Texaco tank (I have lots of non-anodized tanks this size but I wanted some colour)
Car crankcase and crankshaft, much larger in diameter and thicker web than your basic Cox reedy. This crank has the spline rather than the tappered front. The crankshaft was tempered at about 450 degrees F for an hour and was polished/lapped to the crankcase.
Piston cylinder is a #6 (I think), single exhaust slit but no SPI. I wanted to use the Cox exhaust stub (also a car part) hence the non-SPI cylinder. It is a little less messy this way and this also qualifies as muffler for use at my flying field.
The glow plug head is the MECOA replacement head for use with standard short glow plugs. Currently set up with 1 head space/washer and an OS A3 plug.
Spinner is a MP Jet 30mm aluminum spinner sold for use with electric motors and uses a collect. I machined ( I have a Taig Lathe) a new drive washer incorrperating a tapered front to fit the spinner (see picture). Works well and runs true.

First picture shows the crankcase with spinner adapter and the rest of pieces to mount this spinner on the Cox.

First test runs where using a Master Airscrew 7x3 on Sig 25% fuel with additional Castor oil added to bring the total oil up to 25%

Without exahast stub, around 9000 rpm with exhuast stub around 8500 rpm. Needle setting is very broad ( I will have to double check for air leaks as the needle setting seems too broad)

Next step is some more running to run it in a bit and some propeller testing and to install a RJL diesel head and run it as a diesel. There also seems to some extra room in the crankcase between the reed holder and crankpin that I should be able to trim the back of the crankcase a wee bit to reduce the crankcase volume a bit.

cheers, Graham in Embrun near Ottawa Canada

soarrich

My Feedback: (98)

Beautiful engine.

I know it's common practice to 'stuff' the crankcase, but I remember Hal deBolt making an adjustable backplate similar to a kids whistle that could change the crankcase volume. In the report he said he measured NO difference in RPM as he changed the volume of the crankcase. Have you ever done a before and after taching of a engine with volume being the only change?

combatpigg

My Feedback: (3)

That's a good tip, to find "car" lower ends if running the bigger props is the goal.

vauxhall

Nice thread, great engine, congratulations Graham........I always enjoy both reading about and learning about Cox 1/2A engine building and modification tips............John

Strat2003

My Feedback: (1)

Nice looking engine! I wish my Texacos had "broad" needle settings!
I also wish we were allowed to use the aftermarket heads. I can't find the ones with the extraa fins anymore.
Have you got to the point of measuring run times yet?

hfenn

Now let's see the airplane!

GrahamC

thanks for the compliments.

I have stuffed crankcases before and have noted differences but I have never made this mod to a Cox reedy before. Dale Kirn published a description of doing such a mod to the Black Widow in his column in Model Builder many years ago. Simple enough to do and if I go ahead with the mod I will be sure to get before and after figures.

I think the basic idea of stuff the crankcase is to increase the crankcase pressure thereby making it a a better pump. Anything to help a motor breath better always help. Performance isn't always about increased RPM. In this case for 1/2a Texaco I want good endurance while turning a good large prop at an appropriate RPM to match the propeller and airframe.

This is a link to a bit of detail on a modern F2D combat 2.5cc engine. Particular attention is made to reducing crankcase volume. A real jewel of an engine, a high price tag and performance to match.

http://web.telia.com/~u81504305/cyc15pc4.htm

cheers, Graham in Embrun near Ottawa Canada

GrahamC

Thanks for the compliments.

Too bad the rules in the US don't allow for more freeway with engine choice and the use of replacement heads. The rules here in Canada simply limit the engine size to .049. The Cox Texaco is popular but there are a number using diesels. This event is new to me but I have flown a lot of climb and soar and pure soaring so that side of things isn't new but playing around engine like this is new and interesting. i don't know if I will be able to get any competitions for this event this year but I will have lots of fun practicing.

I haven't gotten to the point of measuring run times yet. I will run the engine some more and play around with some different props. So far seems comparable to the Cox Texaco.

By broad needle setting I mean a "broooaad" needle setting; half turn didn't seem to make much difference one way or the other. I could turn it in and sense it getting lean and back it off nearly a full turn. There was no real point at which it peaked. I may still have an air leak somewhere so I will have to take a close look. It may just be a combination of the head/glow plug/fuel/prop combination, that compounded by a slight air leak perhaps. I used a piece of 3/32 ID tygon tubing to replace the needle valve spring. It fits OK but may need some tweeking.

The head is the MECOA 911-049 RJL plug adapter head for use with long glow plugs. The OS A3 is short and doesn't come to the end of threaded portion, makes for low compression and a sort of "double bubble" combustion chamber. So far it's working well with one head gasket. I tried a Fox long plug thinking that it sticking out a bit would up the compression a bit and be benefical but there was no way I could get it to run like that; the prop just rocked back and forth. I have a Galbraith head and Nelson plugs that I may try on this engine but I am sure I will need 3 or 4 head gaskets with that one and it may in fact work better but my intention to install a MECOA diesel head and run it as a diesel.

All in all I am pleased, testing continues.

GrahamC

Ok, here it is.

This a BAG - Born Again Gassy. It started life as an Electric Old Timer and was flown that way for a couple of summers.

Yet to do (obviously from the picture) is to make a new motor mount/fire wall for the Cox motor and fuel proof the pylon which was originally painted with Krylon. Even though I intend to convert this engine to diesel I still want the flexibility to run it as a glow engine if so inclined, hence the need to fuel proof.

I haven't decided how to fuel proof the pylon yet but I am leaning towards a top coat Klass Kote clear. Any other options to fuel proofing?

cheers, Graham in Embrun near Ottawa Canada

hfenn

Thanks Graham, that is a beautiful airplane. Also, do you know Kenneth Parks or Dan McLeod that fly (or used to) with ORCC up there. I used to correspond with them back when I wrote for "R/C REPORT"?

GrahamC

Yep, know both of them. I see Dan fairly regularily and Ken from time to time. Ken is the one who organizes the local SMALL event every summer and does a bang up job of it too. Ken still belongs to the ORCC and Dan now belongs to the Rideau Flyers.

cheers, Graham

hfenn

Cool, please tell them Hollis Fenn says hello.

KidEpoxy

I asked about cheap fuelproofing here- [link=http://www.rcuniverse.com/forum/m_4010132/tm.htm]Finishing Balsa, Cheap Fuelproofing[/link]
Got a lot of good info responses on many techniques and materials, maybe you'll like one

GrahamC

Just saw that thread, thanks for pointing it out.

cheers, Graham in Embrun near Ottawa Canada

curtiss pusher

You ought to check-out Davis Diesel (Yahoo or Google or eBay under cox) for a diesel head for your . .049. They also sell special diesel fuel, a mylar reed for the .049. and a nice connecting rod (small end) seating tool (a must have).

Bill
(Curtiss Pusher)

GrahamC

Good evening Bill. I have dealt with Bob Davis a number of times. I have one of his 049 diesel heads, a couple of his heavy duty reedy cranks, mylar reeds and gaskets.

In fact, I have run this as a diesel using both the Davis head and the RJL diesel head. Both work but I think I prefer the RJL at the moment; some more playing around and that might change however as each has it's advantages. Problem is that I pushed the engine too hard on one run and broke the original crankshaft. I have since rebuilt the engine using a Black Widow crankcase and a Davis heady duty crank. Testing so far shows that something is not quite right, it just does not run quite right. I am in the middle of tearing it down again to check for air leaks, dirt, etc. I am hoping that I will be able to get it running reliably again as a diesel. If not I may use it as a glow engine or I might just put a PAW 80 on the plane and be done with it.

cheers, Graham in Embrun near ottawa Canada

hfenn

Here's mine, a BMJR Super Sniffer weighing in at 13 oz. Test flights to come.

BrykMantis

How was your trip? I also just finished a BMJR Super Sniffer ( All up 18oz). Did you have to add a bunch of weight to the front to get the proper C.G.? I did the electric brushed version per the plans. Have't flown it yet but I plan to this week.

When I was young my Dad and I built a Super Sniffer (About 1973). It had an .049 engine on it and it flew like crazy. One time it flew so high it almost went out of sight. Thermal after thermal, it was amazing. I ran after that little guy for what seemed like miles. Finally it landed in a farmer's driveway. While we were looking in his cornfield he brought back to us.

I never forgot that plane. Now that I am 46 and building my own R/C planes I'd been thinking it would be fun to re-create that plane for my Dad (Now 75) and fly it for him with an R/C assist. (Keep it in his yard this time).

I actually got one of the first kits (bugs and all) after begging Brian for a year to blow up his Sniffer 30" to a 48".
He agreed to the 44" finally after deciding it would be easy to blow up the plans 150%.

Let me know how it goes.

Thanks
Paul

hfenn

I flew my test flight the day before SMALL at the FARM field. Flawless! I caught some lift and got a nice long flight. I did't have to add any ballast. I have a 350 mAh NiMh and Seeker 6 Rx up front right behind the firewall. I like the hatch, no need for a switch, just open and plug in the battery. Power is Cox Texaco .049 with the 8cc tank.

Andrew

Guys --

You've got some great looking planes -- the oldtimers always had graceful lines about them.

PAUL --

What happened to your engine?? Looks like it has thrown a cylinder.

GrahamC

The stuff of all great first (and second and third and ...) flights.

I have always liked the Sniffer. Reminds me a bit of the Vic Smeed Tom Boy. I will have to build one or other (or both ) soon.

Our local SMALL event hosted by Ken Park is scheduled for July 22. Looking forward to the event and some more flying of my Playboy. I have put my Cox motor aside for the time being. I don't have quite a good enough fit with my current Piston/cyclinder set to make for reliable starting as a diesel. I did want to fly this as a diesel so I have fitted a PAW 80 (.049) and just getting ready for some test flights. I will post some pictures later on.

cheers, Graham in Embrun near Ottawa Canada

BrykMantis

Andrew,

That is the beauty of ELECTRICS, no pistons.

Hollis,

I did my first SUPER SNIFFER flight last evening 06/21/2006 at the local Silent Knights (electrics only ) Field. The field in the pictures as a matter of fact. Flying with a 400 motor and a 2-cell Lipo. Like yours, it was poetry in motion. The flight was at least 45 minutes with the motor off about half the time. I guess I had a heavy tail because it took nearly 2oz of lead right under the motor to balance it 1/2 inch behind the main spar.

Not great at looping. Most of the control inputs up there were done with the trim levers. Ahhh, the nostalgia of it all. Can't wait to do it again. Nothing like BUILDING your own plane and watching it ascend.

Paul

hfenn

[quote]ORIGINAL: GrahamC
I have always liked the Sniffer. Reminds me a bit of the Vic Smeed Tom Boy. I will have to build one or other (or both ) soon.
cheers, Graham in Embrun near Ottawa Canada [quote]ORIGINAL: hfenn


Synchronicity is a beautiful thing! Guess what I have on the building board almost ready to cover? Yes a Vic Smeed Tom Boy! I'm building it from a B&W Models short kit which I believe to have some inaccuracies (note the "V" dihedral rather than a flat center and the truss bracing in the fuselage). This will have a PAW .03 for throttle and rudder only control. I love to see the light shine through the built-up framework of a graceful floater. My aim is to be able to launch this with the Tx on the ground and fly as long as possible without my interference (after proper trim flights of course).

GrahamC

Now that is a great way to spend a quiet nice morning or afternoon, just watching something fly so gracefully. Screaming racers or gyrating aerobatic types have their place but give me a pretty and graceful built up plane puttering about any time.

Dan McLeod has a number of Tom Boy's. I don't know if he flies them much and I am not sure if they are RC or FF; I have only seen pictures.

I often like to trim out a glider or whatever and put the transmitter on the ground much to the dismay of others. I am often asked why I mess about with rudder only as well. They just don't get it, maybe someday they will; it took me a long time to figure it out and I am glad I did.

cheers, Graham in Embrun near Ottawa Canada (working too hard and not getting out to fly often enough!)

lildiesel

I just wanted to bump this thread hoping that the original poster might add details about the intended conversion of his modified Texaco .049 to diesel with an RJL head.