Cox Super Power Fuel

Leaving the house right now to go burn through a bunch of it.

Jim

Weather's been crappy here lately, though I've burned through some when the weather cooperates, but it's been rainy here.  Looks like I'll get some flying in this weekend to burn some more.  So far my results from 12 ounces are as follows:

I've restricted the use to only one engine to keep the experiment controllable. The engine used is a brand new stock Cox cast crankcase product engine purchased from Bernie, with a glow plug adapter and insert, as these are cheaper than OEM glow plugs in the long run.  Using three head shims for the 25%.  The only thing I did before initial start-up was to remove the piston and do a reset of the ball joint with the Cox piston rod reset tool.  And I also cleaned out a few metal shavings that Estes generously left in there.  I did a break-in per the instructions on the Cox International website.  The runs have all been made using a Cox 5x3 safety tip prop.  The first full speed run after the break-in gave an average RPM of 15,800 RPM.  After 12 ounces and many flights, the RPM is steady between 16,400 to 16,500 RPM.  These RPMs are right in line with what Cox International says the engine should do.  This is with pretty high humidity, so I don't know how to quantify that versus running it with low humidity.  Not something I've ever worried about.  It could have higher RPM if I switched out the steel reed in the product engine for a mylar reed, but I figured the test would be best if using a stock engine that the average user would have.  I haven't had any problems with overheating or inconsistent/abbreviated runs.  I'll wait until after all the fuel is gone to tear the engine open to check for varnishing, engine wear, and ball joint looseness.


The Scientifical Mark

Mark,

Great test base, I like the way you think.

Not sure you will see much of an increase with the mylar reed, but hey it's worth a shot!

Hi Mark, Jim,
Glad to hear that! I think new fuel should be ok now. do keep us posted, thanks !

Ew

Ok,

I finally have some time to test this fuel.

We have several folks testing under different load conditions so, I am going to go full out and run an engine continuous through the full quart at peak.

I have a brand new product engine as my test subject. All I did to it is reset the ball. I'll be using the quart jug as a fuel tank as I have nothing that big.

I imagine the run time will be close to 3 hrs. I hope to do that in one chunk, but may have to stop and start.

Here are several pictures

to prove it's new.





Ron

Wow. That is torture!

I only recommend you do 3 runs of less than 3 minutes each, with a cool-down period, before the marathon. Might as well replicate the original break-in procedures. It will also help the engine needle reliably during the extended run.

I suspect that even if you plumb up the cap via some superior method, with the bottle horizontal, the head change will prevent a steady run of more than a couple ounces at a time. Even with a topping tank I think the head change will be a problem as the engine will not be run with fuel pressure. Plan to readjust the bottle position throughout the test. I am also concerned about the long fuel line lengths.


Phil

That's a very good point Phil has about the head pressure changing. Maybe you should set aside a couple of ounces and use a 1/2A tank to make a couple of before and after runs. If it isn't already broken in, and all is well with the fuel, the after run should be a little faster on peak than the before run. With the mix containing half synthetic, there probably won't be much varnishing on the cylinder walls.
Good luck. Can't wait to hear your report.
Rusty

I have an idea. To stabilize the head pressure, you could suspend the pickup 2" under the surface of the fuel bottle with a float. As it uses fuel, wouldn't the head always be atmosphere + 2" ?

RknRusty wrote:

I have an idea. To stabilize the head pressure, you could suspend the pickup 2" under the surface of the fuel bottle with a float. As it uses fuel, wouldn't the head always be atmosphere + 2" ?

Siphon effect would be in play.  Floating the bottle in a tray of water might work, but I would fear pulling the line out, and the long lines.  

A uniflow topping tank would prove interesting, and might work, except pressure feed is usually used.  

Kim has some experience with his "little travelers"

https://www.coxengineforum.com/t374-little-traveler-ii-may-19th-2010?highlight=traveler

Phil

I'm afraid I'm way under the radar on the head-pressure thing.  With both Little Travelers, I just tried to position the tank as high as possible (which wasn't much), and ran Bernie's engines in with long test-stand runs from large tanks.

Little Traveler I had a 4 oz Sullivan tank shoe-horned into the fuse of a Minnie Mambo.  It flew for some 35 minutes ( and 15 miles) from my home town to my Uncle Wayne's back yard.

Little Traveler II was a modified "Q-Tee", and was lost in the Mississippi River after losing it's wing in turbulence.  It was packing a 6 oz. tank and appeared to run OK...though it's only flight test had been with an ounce or so.

Ron you could try a simple quart bottle flow-test beforehand, using a spare quart bottle and water or maybe w/s washer fluid, if you feel it's closer to the fuel's viscosity. Orient it inverted for the test.. plumbing the cap with your planned size of fitting/feed line. Find a long length of rigid tubing that matches the ID of your feed-fitting and pierce a small hole in the bottom of the bottle. Force the rigid tube through the hole; so that it extends down almost to the cap.. and seal around the hole and tube with glue or caulking so that it's airtight. (both fittings must be airtight) Fill the bottle with liquid.. "cap it tightly".. and let it flow into a measuring cup. Note the time it takes flow 8oz., 16oz. 24oz. and finally 32oz. You should see little-to-no variation in flow/time from start to finish. This is what the uniflow principle is based on... and it's worth a try.. if you want to attempt to burn the whole quart!!

Actually Ron... to give this fuel a "fair" shake under your test criteria.. you should run a second identical engine/prop.. "peaked-out" as you intend, on another known quality (Sig for example) fuel blend. Burning through a whole quart of fuel in an afternoon of continuous running.. in a Cox .049 engine, isn't something that's typically done. BTW... I have not heard mention of Hobbico's new formulation's "nitro" content. Has this been disclosed?

New formula is 25% nitro 20% oil 10/10 ratio.

SIG Champion fuel is it's competition. I believe it has proven itself, but if you want to send me a quart I'll be glad to burn it up for ya!

You are correct, 3 solid hrs of run time is not typical. We just have the bases covered with other testing methods.

I have a feeling the engine will pass the test if the fuel is as they say it is. It's the most rigorous test I could think of on the bench.

Edit:

If you all feel that my test is not sufficient enough to be an accurate test then please let me know and I will change it up. I was asked to be finished with the test by the end of Oct. I am gearing up for another road trip and my time is limited.

Ron

Phil,

I didn't ignore your post. You made a very good point.

Roddie I may try what you suggested to make it work.

With a larger fuel bottle one may have to periodically shim it up so the top of the fuel level remains consistent. Otherwise, I myself would probably run the test using a smaller fuel tank like a 2 oz RC clunk tank. It's been a while but I think my Black Widow gave about 3.5 minutes run time on 25% nitro fuel. That is 60 cc / 8 cc = 7.5 times the size of a Black Widow integral fuel tank or 60 / 5 = 12 times the size of a Babe Bee integral fuel tank, about roughly 30 minutes run time. A 4 oz would give probably 45 minutes to an hour run time.

The bench test indeed would be a fairly grueling one as the engine obtains better cooling moving through the airstream, whereas on the bench its the propellor slipstream running static. But I think the test should prove the sufficiency of the fuel.

In standard scientific standard, one would run identical tests using the Sig Champion along side the new Cox fuel, with identical new engines with same compression and piston con rod sockets reset. But I have a feeling that the new Cox fuel will probably perform just as well as the Sig Champion fuel. If one ran a side by side comparison with say a fuel of similar consistency as the old Cox fuel, say standard RC fuel with 25% nitro, 18% oil with 2% of it as Castor, would substantiate the level of wear and tear one would expect over the recommended fuels.

I've just never tried using the standard RC fuels, as I value the worth of my legacy Cox, Testors/Wen Mac, OK Cub and A.C. Gilbert engines.

Well i don't know but one thing is i broke the rod on a older TD 049 bench running it too long at peak this was probably 7-8 mins.  So i would be interested to see if you blow yours up (not that i want you to) It may would be OK if not peaked out though !! Eric 's

I may change my test around as there seems to be some concern as to the validity of it.

I will say this...over the lifespan of an engine it may build up many hrs of runtime. It's not all at once I agree, but wear is wear.

That being said I was just tasked this morning with another short notice trip on top of the one I already had to do. Whatever I decide I need to figure it out quick. I may just bolt the engine to something with a 1oz tank and fly 32 flights in succession.

Ron

So if I missed this test idea, apologies

If I was to test the new fuel (I have extensive testing experience as an Army Test Officer in Operational Test Command) I would use at least Six engines all of the same pedigree and basic physical condition...all six would be tested to failure: three with the suspect so called Cox fuel with wrong oil (by our understanding) and three with the new blend with a better oil package

I suspect this test would be time consuming in that even the wrong oil package fuel will probably run a very long time in a typical Cox .049 before any failure or noticeable wear shows. And certainly the new blend will most likely never show measurable wear within any reasonable time

Quite frankly each of us already knows from experience that some synth oil is OK as long as there is enough Castor to adequately lube the con rod ball joint. None of us knows for sure what the ratio truly is.

I have done a lot of searching on this subject, and there are a very few who religiously believe 100% synth is just fine. Generally, the consensus is: for older iron engine designs the 50% or greater ratio of Castor oil is good for several reasons (no sense repeating it here as we all know the properties of Castor oil)

I would hope the fellow who is sending the sample for this testing has already done a comprehensive web search on this subject, and that siad he should easily understand OUR concern with the Cox fuel they sell as having a terrible oil content % and ratio. And with out any results from all of you testing the sample product he should already be able to write the report for his management to source the newer blend and appropriate marketing strategy to make Tower and other outlets some money from better sales curve

getback wrote:Well i don't know but one thing is i broke the rod on a older TD 049 bench running it too long at peak this was probably 7-8 mins.  So i would be interested to see if you blow yours up (not that i want you to) It may would be OK if not peaked out though !! Eric 's

In competition you have 8 minutes to get the full pattern in.

fredvon4 wrote:So if I missed this test idea, apologies. If I was to test the new fuel (I have extensive testing experience as an Army Test Officer in Operational Test Command) I would use at least Six engines all of the same pedigree and basic physical condition...all six would be tested to failure: three with the suspect so called Cox fuel with wrong oil (by our understanding) and three with the new blend with a better oil package.

Your working for the government reminds me (and please don't take me seeriously!)   Having worked for the Air Force and Army in contract administration, (was a project engineer on a $39 million construction project, among others), I would have written a performance specification with requirement for adherence to Davis Bacon Wage Act, safety IAW EM 385-1-1, submission of a test plan, mobilization plan, site plan, utilities permitting, and to kick off we'd have a partnering meeting set up by contractor's consultant's subcontractor, and a government cost estimate which would be reviewed by at least 6 different departments including environmental, bioenvironmental, civil engineering, logistics, funds management, and legal, to which Contracting would also add about 350 pages of boiler plate government requirements after review by others, before advertising in the Business Commerce Daily.
I am being facetious, please don't take me seriously.

I gather that this test is more of an informal one to give feedback back to Hobbico, on what the modeling community thinks of the new fuel. It doesn't appear to me to be an official endorsement as to certifying validity requirements. IOW, KID TESTED, MOTHER APPROVED

GallopingGhostler wrote:

IOW, KID TESTED, MOTHER APPROVED

Spot on, George. But even without scientific method being employed, I think we do have credibility. The passion of our ranks is undeniable from reading these posts, as well as our general consistency of agreement on our fuel needs. After all we're the customers, so we must be right.
Rusty

Kim wrote:I'm afraid I'm way under the radar on the head-pressure thing.  With both Little Travelers, I just tried to position the tank as high as possible (which wasn't much), and ran Bernie's engines in with long test-stand runs from large tanks.

Little Traveler I had a 4 oz Sullivan tank shoe-horned into the fuse of a Minnie Mambo.  It flew for some 35 minutes ( and 15 miles) from my home town to my Uncle Wayne's back yard.

Little Traveler II was a modified "Q-Tee", and was lost in the Mississippi River after losing it's wing in turbulence.  It was packing a 6 oz. tank and appeared to run OK...though it's only flight test had been with an ounce or so.

Sorry to hear your LT2 was "lost at sea". It was remarkable for you to use only an .049 engine to do the unthinkable to beneift a charitable cause. Even a 1 oz (30 cc) tank has nearly 4 times the capacity of a Black Widow 8 cc tank, but you flew for an extended amount of time.

Do you plan in the future to attempt your long distance journey again?

RknRusty wrote:

GallopingGhostler wrote:IOW, KID TESTED, MOTHER APPROVED

Spot on, George. But even without scientific method being employed, I think we do have credibility. The passion of our ranks is undeniable from reading these posts, as well as our general consistency of agreement on our fuel needs. After all we're the customers, so we must be right. Rusty

Oh, of course we have creditability. I guess what I was referring to is through official scientific endorsement, which normally a manufacturer would do. Fox had a lab where they tested their engines, running them to determine life expectancy and whether they had a good marketable product or not, and to test improvements.

My lab is the front end of an airplane.

GallopingGhostler wrote:

Kim wrote:I'm afraid I'm way under the radar on the head-pressure thing.  With both Little Travelers, I just tried to position the tank as high as possible (which wasn't much), and ran Bernie's engines in with long test-stand runs from large tanks.

Little Traveler I had a 4 oz Sullivan tank shoe-horned into the fuse of a Minnie Mambo.  It flew for some 35 minutes ( and 15 miles) from my home town to my Uncle Wayne's back yard.

Little Traveler II was a modified "Q-Tee", and was lost in the Mississippi River after losing it's wing in turbulence.  It was packing a 6 oz. tank and appeared to run OK...though it's only flight test had been with an ounce or so.

Sorry to hear your LT2 was "lost at sea".    It was remarkable for you to use only an .049 engine to do the unthinkable to beneift a charitable cause. Even a  1 oz (30 cc) tank has nearly 4 times the capacity of a Black Widow 8 cc tank, but you flew for an extended amount of time.

Do you plan in the future to attempt your long distance journey again?

Yeah, right after the loss of LT2, I started drawing up plans for another Little Traveler named 'Scoot Wagon'...basically a flying 12 oz. fuel tank. It's still on the back burner, but I may start gluing it up this winter.
It's probably just as well that I took a break...I think my buds were starting to avoid me for fear of being hit up for cash!