300 mph Cozy IV

[spitzy]

Anyone have any ideas about how to modify the Cozy IV to cruise at 300 mph?

[Lynn Erickson]

Anyone have any ideas about how to modify the Cozy IV to cruise at 300 mph?

the short is. take the cozy IV plans and make as many modifications as nessesary until it looks and flys just like a Lancair IV with a TIO550. the cozy is a 200 mph aircraft if you want to go 300 build a 300 mph aircraft.

[TMann]

I have to agree with Lynn on this one.

The Cozy (because it is a side by side) presents a larger frontal area. As a result, it presents more resistance than say a Berkut.

 

A better project in the canard line would be an Open or Long EZ. Closer to a fast design such as the Berkut if it's a sports car utility that you are looking for.

 

There is a segment here that Richard Riley wrote about building a 250kt EZ.

 

Maybe buy a set of the Berkut drawings.

 

Here is a link to the post for the 250kt Longe-EZ:

http://www.canardzone.com/forum/showthread.php?t=1577&highlight=250

[chasingmars]

Looking only at first order effects, power scales roughly to the cube of velocity, and linearly with effective flat plate area at a given altitude.

As altitude changes the true airspeed is proportional to the inverse of the square root of drag. So, that gives some basics to frame your question.

 

Talking "advertised" numbers, the Cozy "advertised" cruise is 220mph at 8000 feet on 75% of 180hp. Here it gets a 1000nm range (again, advertised) on about 52 gallons of 100LL. This is about 190mph IAS.

 

So, changing nothing but power, doing whatever mods are needed to ensure the aircraft is safe at 300mph (which is above the published Vne so this is non-trivial) and assuming you can do this somehow magically without any weight impact, to get 300mph under the same conditions would need about two and a half times the power for the ~35% speed increase.

 

That means, powerwise, about a 460hp engine... remember, if you add weight, you need even more power. Too bad the Innodyne is fuel hungry vapourware. You have about an hour or so fuel for a PT6A though!

 

Drag reduction is the best way to increase speed on most planes though... so... make all the antennas internal? Already done. Slippery glass airframe? Already done, etc... A whole new wing design and foil shape taking into account a section with a drag bucket in the right spot for the Cl you're planning on (just over half the cruise Cl of a Cozy) might shave a few hp off that figure, which is a major redesign, probably one of a dozen to do this... and no more weight or it takes more power.

 

In short, gains of knots to a couple tens of knots are acheivable it seems, but the shear nature of drag makes the kind of gains in speed you're talking about very difficult to acheive if they aren't designed in from the drawing board... at least, at a given altitude, but I don't think the Columbias are turning 300mph on the deck

 

Me, I'll take being the second fastest on the ramp, with a third of the operating costs.

 

Easiest (for relative values of "easy") way to go faster if you want big speed gains, install oxygen and a turbo'd engine, and fly higher. If your turbo engine can hold 160hp to 25,000 feet (no mean feat to start with), and you're confident in your engineering ability to manage the Vne and flutter issues (and I'm not sure I'd be too quick to nod on that one), then ingnoring a few effects that will sap some speed (prop effectiveness, etc) at 25,000 feet you're starting to get close to that 300mph TAS number.

[Lynn Erickson]

I have to agree with Lynn on this one.

The Cozy (because it is a side by side) presents a larger frontal area. As a result, it presents more resistance than say a Berkut.

 

A better project in the canard line would be an Open or Long EZ. Closer to a fast design such as the Berkut if it's a sports car utility that you are looking for.

 

There is a segment here that Richard Riley wrote about building a 250kt EZ.

 

Maybe buy a set of the Berkut drawings.

 

Here is a link to the post for the 250kt Longe-EZ:

http://www.canardzone.com/forum/showthread.php?t=1577&highlight=250

frontal of a wider fuselage does add to the drag but the lancair is side by side. the lancair also has a vey big engine and a very thin wing. it also should be noted that the lancair's need at least 350 hp two get up to 300 mph and even then that is top speed not cruise speed. even the berkut is not a 300mph machine. the 540 model tops out at about 270 mph

its not the frontal area that limits the cozy design its the wing. the big fat wing on the cozy has very high drag above 200 mph. it is basicly a glider airfoil. selected for high lift ( with no flaps ) and high altitude cruise performance. designing/building a true 300mph aircraft is a very different amimal. look at the lancair evolution to see what it takes. the solution is really not that difficult, build a lancair evolution or just find a designer/ aero engineer and give him a couple of years and 5 million, or so, dollars and you two can cruise 300 mph .

[Jack Morrison]

Lynn is absolutely correct about the wing. I would in no way give up the glide quality and safety of the canard wing, I have been in a Lancair with power pulled bach and they drop like a rock. I have seen 59 in mp at sea level (about 448 hp) and my best speed at 10k is 291 mph with a fixed pitch prop. 66/103 at 3000 rpm. Above 250 mph is very difficult to achieve without a larg increase in fuel burn. At 250 mph cruise, 2450 rpm, I burn 19.6 to 20.3. That gives me about 2.4 hr cruise before I will need fuel.

 

Jack

E Racer 113

[Spodman]

how to modify the Cozy IV to cruise at 300 mph?

Erm. Why?

[chasingmars]

As altitude changes the true airspeed is proportional to the inverse of the square root of drag.

Sometimes my brain accidentally spits out nonsense... hmmm... I meant:

"As altitude changes the true airspeed is proportional to the inverse of the square root of DENSITY." (to a rough first order approximation)

[TMann]

Erm. Why?

Yeah ...... having the potential/capability is one thing but keep in mind, once you exceed 250kts it's a new set of rules.

[Rydogg]

I came across this article a few weeks ago, I know it's from Vans but the principles still apply. We all know that our TAS increases as we climb but VERY sure that your aircraft structure can handle (ie. is designed for) the stress' and flutter at those higher speeds and altitudes. The article points out a few good reasons for having a normally aspirated engine instead of a turbo. Food for thought.

hp_limts.pdf

[Wayne Hicks]

And the Lancair's top speed claims are up very high, 25,000 feet. down low, they fly around in the 270's.