what is the most powerful cox .049

This is perhaps what the original question is about (from aerotools);

Also prop choice is very important as some tend to flatten out at higher rpm.

nitroairplane wrote:
True I only really fly .049's with a 6x3 prop or more anything less i feel they sound like the are going fast but don't really have that PULL that I love.

The 6x3 is a little big for the engine, if you build something lighter and slimmer (plane that is) you can use a smaller prop and then really have the engine get into song.

Yeah and better throttle response.
I don't really do speed planes just sports but I like them to be hot at top end but able to go slow.

You need only enough "pull" the keep the plane from coming in to meet you in manuvers. Anything more detracts from the plane's flying characteristics.

If you like "pull" move up to a Class C stunter.

SuperDave wrote:You need only enough "pull" the keep the plane from coming in to meet you in manuvers. Anything more detracts from the plane's flying characteristics.

If you like "pull" move up to a Class C stunter.

good point sd

I use 5x3 on all of my CL planes. It makes them fly faster. The 6x3 slows them down and tightens the loops. 5x4 give tons of speed but big loops. Thank Rusty for that info.

SuperDave wrote:You need only enough "pull" the keep the plane from coming in to meet you in manuvers. Anything more detracts from the plane's flying characteristics.

If you like "pull" move up to a Class C stunter.

I was talking about pulling the plane
Not the lines we were talking RC.
But yeah the biggest CL plane I have flown is the ringmaster.

Godsey3.0 wrote:I use 5x3 on all of my CL planes. It makes them fly faster. The 6x3 slows them down and tightens the loops. 5x4 give tons of speed but big loops. Thank Rusty for that info.

You got it! Bernies Cox Grey 5-3 is just about right for most of our 1/2a C/L planes and yes a hicomp head will help your engine spin it faster, giving you more power, more power = more speed, more speed = better line tension, better line tension = better stunts!

P.S. If its too fast, add more line.

This stuff can't be summed up in a few words. As RPM goes up, so does power...to a point. If you look at the previous power curves, notice that after a certain point, power decreases.

what is not shown is the torque curve...which decreases at higher RPM.

For a nice clean, light airframe, you can use a smaller diameter, higher pitched prop. For a plane with larger frontal area and more drag, you would need a larger diameter prop with lower pitch. Sometimes you need to vary prop size, fuel, and compression to maximize your setup.

Remember when you alter the engine to operate beyond its designed performance window, expect things to wear out and break sooner than normal. One of the first to go is usually the ball socket so make sure you reset it often.

If you really need performance beyond the design limits you would be better off investing in a modern more powerful engine.

George

Has everyone forgotten the dragonfly?

Everyone hates it cuz it looks like a barf bag, and that's being courteous.

I want a dragonfly, just haven't found a used one to add to my collection

The original post didn't specify fastest reedie or fastest TD. TD's will always be faster, period, just the nature of the beast. It all depends what type of 049/051 you are looking to modify. I get 21K out of my Killer Widow 051, but it's a custom engine.

engine049 wrote:Has everyone forgotten the dragonfly?

Everyone hates it cuz it looks like a barf bag, and that's being courteous.

Barf bag

Yeah, it ain't pretty.

Never seen one spool up. Cox claimed it was pretty powerful. I doubt more so than a TD.

cribbs74 wrote:

engine049 wrote:Has everyone forgotten the dragonfly?

Everyone hates it cuz it looks like a barf bag, and that's being courteous.

Barf bag

Yeah, it ain't pretty.

Never seen one spool up. Cox claimed it was pretty powerful. I doubt more so than a TD.

i want a bark bag

So, with out a doubt, to answer the question for what was the most powerful Cox .049 engine was, the Cox .049 TEE DEE @ 21,00 RPM which would mean using a 5x3 prop is the most powerful .049 engine cox ever made.

And with proper fuel mix and nicely broke in TD .049 is as strong as any TEE DEE.051, look at the RPM charts for the .049 and the .051 TEE DEE Speeds with various prop sizes and pitchs, they both attain the same speeds with all props, so the only differance is a very slight bit of HP with the slightly larger piston in the .051 so it may out climb the .049 slightly if its running good, not sure it would be enough to even notice, unless you go to the TEE DEE .09.

My question to add to this if I can is, would the TEE DEE.049 even out preform the Cox .074, would I be better to run a TEE DEE .049 over a standard Cox .074 in a kit that calls for a .049 - .074 size engine, building the Herr Aqua Star Seaplane 1/2 A RC, & the Herr P51 Mustang 1/2 A RC

You can't beat cubic inch when it comes to torque. The QB is twice as heavy but can handle larger props and beats the .049 on 6x3-4 props, while also offering a throttle ability. The QB can spin a 6x3 prop at about 18000rpm and a 6x4 prop at around 16000rpm.

Surfer_kris wrote:

microflitedude wrote:TD .051 with high compression head will give you the most power, use a standard head for more RPM.

This doesn't make any sense, more rpm means more power.

Well, almost. With respect to reciprocating engines, horsepower (power) is simply a calculated number. Quite meaningless in the real world actually. Power = torque x rpm x K (a constant). Can't remember what K is - Google is your friend. So, some examples:-

If you can produce more torque at the same revs then you have more horsepower.
If you can produce the same torque at more revs then you have more horsepower.
It would be well possible to produce more torque at a few less revs and still have more horsepower. I believe the diesel conversions give this result.

Further, compare a 500hp Ferrari and a 500hp truck. The Ferrari spins out to around 12,000rpm, the truck to about 2,200rpm. The truck will haul many tons, the Ferrari will go fast, but you'd miss this crucial difference if you took any notice of the hp figures. The truck engine produces bags of torque at low revs whilst the Ferrari produces bags of revs and little(ish) torque, hence the same hp.

That's a very simplistic precis of the topic .

Nicely done Dins

But I just noticed something,

The TEE DEE .049 Spins a 6x3 at 18,500 according to the chart, and the .074 shows it spinning a 6x3 at 17,800, so does this not answer my question, more RPM = more power with the same Prop Pitch, again the lil TEE DEE out preforms

dinsdale wrote: With respect to reciprocating engines, horsepower (power) is simply a calculated number. Quite meaningless in the real world actually. Power = torque x rpm x K (a constant).

It is far from meaningless, Power is the amount of energy that is being delivered per unit time. For a given prop you can calculate the developed Power directly from the rpm it is spinning at. You cannot increase the rpm without increasing the power you are giving to it.

The high compression heads are for higher rpm applications (small props) and the low compression heads are for lower rpm applications (larger props). Heads shims are also used to adjust this further. This is a timing effect, on ignition engines you vary the amount of pre-ignition depending on the rpm, but we cannot do that on our glow engines.

So with a 6x3 prop on my lil .049 TEE DEE for both the Herr Aquastar (recommends .049-.061) or the Herr P51 Mustang(recommends .049 -.074) the lil TEE DEE should be fine and not under powered

A cox TD .049 will not spin a 6x3 prop at 18500rpm, that would require a good .061 engine.

I don't have the Aquastar myself, but it looks big and you would be better of with a Norvel .074 or an Enya 09 for instance.

I flew an Aquastar with a Norvel .061 ame and it did pretty well. The engine is not suited to such a draggy airplane but once it got up to speed it flew very nicely. The first few moments after a hard hand launch could be exciting if the engine stumbled at al.