Cox vs. Norvel
 

With the massive amount of Cox parts available, plus the cheap prices for them, what is the general consensus regarding the use of Cox engines instead of Norvel for the reasons mentioned...just curious!

There is no real reason to use cox, as I see it, other than nostalgia and for already having too many of them...

Thanks. The reason I asked, and please correct me if I am wrong, Cox engines seem to outlast any of the Norvel engines by MANY years.

Never heard that before, and I haven't worn out any of my Norvel engines either. Are you talking about the revlite or the earlier ones?

I would expect the cox sure-starts to be the least long lived engines...
All the new old stock (cylinders and pistons) that are being sold are also from those later runs with lower quality.

OK Thanks!

COX engines seem to last longer because folks can't get them to run, and when they do, run times are short.


Sorry, couldn't help myself --- that statement is false. But, like Mr COX, I've not been able to wear out my NORVELs. Good lube, reasonable nitro, and they run for a long time.

I have to agree, The TD's and Conquest .15 are fine. The Cox stuff is outdated. Just had to mention Mr. Cox as not being a fan of Cox motors.

Hard to beat an NV .074 as a small RC engine, head and shoulders above any Cox throttled offering (not counting the Conquest but that's almost apples and oranges). And currently available, and although more than a Sure Start certainly not expensive.

Yes, the conquest is in a different league, very "non-cox" in its construction...

But I've started to like the Queen Bee when running it on diesel, it actually performs quite well and does about 4000-10400rpm on an 8x4 prop;
(I guess the Norvel .074 is even better on diesel though...)

http://www.youtube.com/watch?v=KLFfH1vQKSY

Not too shabby. Nice combo too I bet.

My Cox Surestarts start by hand with only a few flips, run very well, and are consistant runners. Plenty of power for anything under 14 oz or so. I have one on a sport Pylon racer that has well over 50 flights of about 5 to 6 minutes each and still runs strong. I've probably burned 2 quarts of fuel through this one engine.

If you can't get a Surestart to run you will have no better luck with a Norvel. Stick to electrics. Norvel engines are a different class of engine for a little heavier airplane and have their own unique "way about them" just as the Cox engines do.

Practically all of the bad memories some have with Cox engines are related to engines with tanks. The Surestart is a different breed without the troublesome tank.

The only problem that I can see with the Surestart is the lack of a throttle.

No throttle, seriously??? Are you not aware of the throttle Cox sells for the Sure Start? They were introduced almost three years ago. No offense but where have you been as they have been discussed all over this forum?

1) Here is the link to Cox Engines Sure Start throttle: http://coxengines.ca/throttle-conver...49-engine.html
2) Here is a link to a You Tube video showing the throttle installation: http://www.youtube.com/watch?v=pvpmLy0ToYE
3) Here is a link to a You tube video showing the running engine with the throttle: http://www.youtube.com/watch?v=Iq_Q1ODC8Ko

Check these out as the throttle conversion is only $14.95.

Good luck!

That's not a throttle, it's a choke. It only lowers the engine revs by making it run too rich, that's what people used in the 60-ties as an add-on to CL engines. Other engine manufacturers are well past those attempts now though...

Mr. Cox: We had this conversation three years ago when the throttle was first introduced. I designed it and then had one of my machine companies manufacture it for Cox International. Did you ever buy one? It is ONLY $14.95. Call it whatever you want but it works as designed and regardless of what was done in the 60's, this throttle works with the inexpensive Cox reed engines. Thousands have been sold and those using them are very pleased with the performance at a VERY SMALL COST. It allows them to control the speed of their engines from idle to full power and then to shut down the engine when their flight is complete! For the authority you try to be on this forum, I am rather surprised you haven't bought one. Like I said, it is only $14.95.

Yes other manufacturers are beyond this concept as their engines are far more sophisticated. The Cox engine was designed, I believe, in the 1950s. They are still the same basic design, not nearly the current technology of modern engines. This throttle was developed to work with the level of technology of the Cox engine at a very inexpensive price. Quit being so negative and buy one. Then, after you use it, please explain to me how you would develop and manufacture an alternate product with at least comparable performance, and sell it "retail" for under $15.00?

I appologize for sounding so negative, and yes we had this discussion when they first came out. Before that, there have also been several DYI chokes presented on youtube etc.
There was also a more clever solution presented then, a disc is attached to the main needle and the needle will turn together with the choking disc, thus making some effort to also lean the low-end.

To me it is false marketing to sell these as a "throttle" when it is a choke, so that's why I may have used a too strong language.

As a comparison, even the proper carburetors on the Queen Bee engines will run too rich at the low end, but these ones can be fix with a little trial and error to make a non-adjustable compensation. So throttling a read engine is not difficult in any way.

I simply cannot see any reason to buy a choke (even at $15), plus the head "adapter" for a regular glow plug and a few extra hot regular glow plugs to go with it. Just to run an engine well below its potential, even if it doesn't quit when heavily choked. To me a proper carb would have been much more interesting, even if the cost is higher. I have indeed bought TD carbs from Cox international.

Perhaps something that could be used on both the TD and Sure-start engines would have been feasible, and would have a larger market.

Well yes a throttle is available as is the old exhaust restrictor which actually works quite well. I have not tried the choke throttle although I have one.

The thing is that it is a bit of a challenge to build the right airframe at the right weight to carry the extra weight and still have stellar performance. Most of my Surestart planes weigh 10 to 12 oz ready to fly and are hand launched. Add the weight of a throttle, linkage, servo, wheels and gear and you are flying a much different plane with the added weight and drag. Now go find a paved runway to fly from so you can take advantage of the new throttle because it sure don't have the juice to get out of the grass around here.

So yes there are options for a throttle as you so tactfully put it, but in my case it is usually not worth the trouble. Therefore MY Surestarts don't have that feature.

https://www.rcuniverse.com/forum/Wanderer

049flyer - you take off 1/2A planes from the ground? Throttle or not I hand launch mine.

Mr. Cox: Thanks for your reply. A throttle is defined as "a device that restricts flow to reduce power and speed." This is exactly what the Cox throttle does and why it is called a throttle and NOT a carburetor. We discussed this in detail three years ago. It is not false advertising and your comment is not appreciated. The function of the Cox throttle has been explained in great detail repeatedly so anyone considering its purchase knows exactly what they will be getting.

To redesign the standard Cox reed engines to have a carburetor and function similar to the Queen Bee would be far too expensive, well exceeding the cost of the engine itself. We also discussed this in detail three years ago.

Regarding the various homemade devices on You Tube, yes they regulate engine speed and are fine for an individual to experiment with for their own use but they are not conducive to high volume production. Please understand the requirement in designing the throttle was to make something inexpensive, easily converted, easily mass produced and extremely simple to use. This is what we did.

Best Regards....

Ace used to make a servo controlled needle valve very cheap (low priced) that was just a needle valve which went into the hole in the backplate of the ___ Bees. It would be similar to the Surestart choke/throttle meaning no mixture control. The reedies will fall out of the air at around 6,000 rpm, so a low idle is not important like on a larger motor with a more efficient prop. I have many reedies, and do not prefer them when a TD or Norvel is available. They have their place I suppose. By the time a throttle is purchased, and a motor, you could buy an AP .09, Norvel, TT .07, or ahem electric(no I didn't day that) Having said that, I do have about a dozen reedies looking for a plane to use them up on. My last RC one broke on a road trip back from the swap meet. (it didn't sell) This pic is all that remains;-(

Well, I not a native english speaker and I could get the words wrong by comparing to my native language, but I do believe that there are also technical terms that can deviate from the general meaning or definition of words.

In a carburetor you have a throttle valve and a choke valve, this is very general. The difference between these is in their position relative to the fuel jet (or spray bar), the throttle valve regulates the total flow through the carb (and hence the engine speed) while the choke valve acts to give the engine more fuel at any given throttle setting by choking the intake.

In a regular RC carburetor with a rotating barrel, we have the two exact same functions, it is just that they are both operated at the same time. This is also why you absolutely do need a low end adjustment on the these carbs. This can be in the form of an air-bleed hole, a slot in barrel or different hole diameters before and after the barrel, in order to compensate for the fact that one is also effectively choking the engine when throttling down.

Had the Surestart "contraption" been called a choke, I think everyone with engine knowledge would immediately understand what it does, without any need for further explanations.

Here is an image from wikipedia to illustrate the nomenclature, please do amend the wikipedia page if they are wrong;

http://www.rcuniverse.com/forum/atta...mentid=2033242

Mr. Cox: I realize you are from Sweden and all of you MUST feel they are correct in EVERY situation so I am done with this conversation as it is now going around in circles! I very well know how a carburetor functions.

Some planes I do. I have a full house (remember that phrase?) Goldberg Jr. Falcon that is a blast to fly off of the pavement when I can find some that is not being used. Touch and goes! I have a TT .07 in that one.

I had a Sig .049 Rascal with the TT .07. True is isn't as powerful as Norvel but it had the best idle and "big engine" ease and consistency of any 1/2A engine I have used. I wouldn't mind have a Junior Falcon as they are a great airplane.

We are the distributors of the "throttle" in question and have sold many thousands of the little marvels. The term "throttle" is used in its colloquial North American form as in "restrict" (in this case RPM) as opposed to its strict mechanical interpretation. Even Cox called their version of an RPM reducer a “throttle ring” although, technically, it is an exhaust restrictor.

We make no bones about the throttle being an airflow restrictor. However, it is incorrect that the throttle merely enriches the fuel / air mixture.

Because of the unique nature of the “Surestart” choke tube, the venturi effect that is created actually also reduces fuel flow; not exactly proportional to airflow but nonetheless at a ratio conducive to the engine functioning properly at lower RPMs.

It is not a requirement to purchase head adapters to successfully use the throttle, as the throttle permits engine operation at sub 7,000 RPMs with the stock head; low enough to land virtually all aircraft designed for use with a Cox .049 reed valve engine.

Head adapters can be used if a modeller desires an RPM increase beyond what a stock head would provide or a low idle beyond what a stock head would provide.

Our throttle has been reviewed by a major model magazine (Fly RC) here:

http://www.coxengines.ca/files/review.pdf

and, so far, no one else has successfully launched a competing, low-cost, alternative, except the ubiquitous throttle ring; which does not permit the simultaneous use of a silencer / muffler.

Bernie
www.coxintenational.ca