marbleturtle

The last time I talked to Greg, he was planing on bulking up the canard and main wing spars ala Berkut. I don't know what Vne he is targeting, but it will be higher than the standard. Also, he is converting the rear single seat (Cozy III) to a permanent fuel tank. I figure you could get an extra 30 gallons back there. He's offered me a ride when he's finished... but I'm almost afraid to ask.

The short KISSy version of how a turbo works is... Engines have an optimum Fuel/Air mixture ratio for generating power (doesn't matter what that is right now). Normally aspirated (ie: no forced air intake) engines suck air in with every cycle of turning pistons (or rotors ). The fuel is mixed with air, hopefully at optimum mixture for the conditions and kablooie! Power stroke. Now if you take that same engine and you use forced induction (turbo, supercharger, air intake pointed into the wind, etc) more air is forced into the same space than is sucked in through normal aspiration. To the larger volume of air in the cylinder (rotor!), you add more fuel to keep a good air/fuel mixture and viola! Bigger kablooie... More power, same engine size. Things get more complicated with detonation (squished air and gas that KABLOOIE have a premature explosion problem). Also different applications have different concerns: 1. A supercharger is an airpump driven by an accessory belt... not used as much as turbochargers since its one more belt to break. Also more effective at generating torque at low RPM rather than higher RPMs. 2. A turbocharger is an airpump driven by exhaust gasses. One big metal pinwheel in the exhaust system uses the pressure of the exhaust gases leaving the engine to spin up. The turbine in the exhaust is connected to a shaft which is a connected to a big metal pinwheel in the air intake system. The tubine in the air intake is spun by the turbine in the exhaust which in the end forces air into the engine. The biggest issue with a Turbo is that clogging up the exhaust system with a bunch of metal parts causes heat retention. The hot exhaust gases which normally just fly out the exhaust now spiral around the added plumbing under pressure before leaving. Turbos and exhaust plumbing get hotter than non-turbo engines. 3. Forced ram air intakes... never seen one on a plane. My Yamaha R1 has it though. Its basically an intake system pointed forward to get the benefit of all that blowing relative wind. The faster I go, the more air getting forced down the throat of my engine. It actually makes about 20 more HP at speed verses standing still. The downside is rain, ice, dust, Highway Patrol, bugs, soccer balls... anything that could get forced into the system from the airstream that would clog the filter or keep the engine from going squish kablooie. Well... I hope that helps some. It gets more complicated, but nothing that can't be overcome with a little extra work. At 8500 feet, I think the air is thin enough that a turbo will offer great performance gains. My $0.02.

... or we could post here for free and get you to fill in the details! One could argue that since the Cozy has been around so long, we could just pack up this web site... there's nothing new in Cozy Land. [edit] Well that sounded harsh. Actually I am going to get a few years worth of back issues and a current subscription. [/edit] Dihedral! Thank you No 4! I was having a brain fart when I posted and couldn't remember the term for nothing.

... also for more photos: http://www.eracer.org/ezhangar/

... first I thought their smart level needed to be re-calibrated!

This may be an old topic... But what is the reasoning behind making the canard up-swept instead of level. I saw a few of these at EAA airventure 2003 and later saw an article about it. The tips are higher than the root causing the tip vortices to flow above the main wing ailerons instead of into them? Is this valid or disproven? Just curious.

Take a dart... throw it up in the air. Heavy end always comes down first.

... yes, but with a turbo clogging the exhaust, less of that heat flies out the tail pipe!!! I researched the small block idea. I saw a picture somewhere of a Long EZ with a small block V8... anyone know where that was? Another question would be, could you get a small block V8 that is light enough, but has enough power at 2700 RPM to not require a PSRU? The small block V8's generate so much torque, that I think you could get the required HP at that low of an RPM. John, I still think the positives of the TURBO outweigh the negatives, but heat retention from the exhaust is one of those negatives!

Would a manual fuel cutoff hurt a fuel injection system? I've always heard don't allow a fuel injection system to go dry.

... and brought them out through a hole cut in the roof! I think it was on TV!

I KNOW I can't slap the kids in back from the front seat... that's why I'm putting an electric shocker (the cattle prod variety) in the back seats with push button activation from the front seats. That'll shut 'em up!!!

There are several different types of aircraft you can look at that have both faired gear and retract options. The difference quoted between the two is usually substantial. I haven't seen any articles yet specifically related to the Cozy, but I don't think its unreasonable to expect a 20 mph increase. Part of the equation is the design of the prop. If someone converted to retracts without changing their prop to take advantage of the lower drag, then they may not see much improvement. It would be like dropping a small block V8 in an old Hyundai without changing the gearing. The darn thing is still only going to do 80mph because the low gearing was designed for the lower hp. Now switching to retracts is not adding power, but it does reduce drag. At the speeds the Cozy can travel, it seems reasonable that we can realize a good increase in speed with retracts and a higher pitched prop that can take advantage of the reduced drag. I guess the $6000 question is... how much?

Forgetting to lower the gear is not an issue for me... I'll need to lower the nose gear every time I land so what's 2 more?!?!?! Price is the biggest stumbling block for me. But since we are up in the 200mph club, resistance is exponentially higher than say 160mph so a 20+ gain seams reasonable. I wanted a 3rd tank as a sump for an automotive conversion engine with fuel injection, with retracts it can go in the bulkheads normally occupied by fixed gear. The gear down drag of the retracts gives a little extra slowing power on a steep final. The spar is designed for 10+ g force. Impact is cushioned by the rebound in the gear. Most high performance aircraft carry the gear in the same place. Wider track for better stability on the ground or trying to land in difficult conditions. Everthing appears positive, I just don't know if I can get past the price for the hunk of metal parts you get in return. Decisions decisions.

I know where you can get a Rotary engine for $1500! Whoops... uh... I mean... how much lighter?

... on a more serious note. John, are you going to use the EWP to replace or augment the mechanical pump? It appears that 1 primary EWP and 1 backup EWP could be used and still save 6 lbs over the mechanical. It also appears that you could have control to manage the flow for desired cooling results, not just RPM based. Is Todd Bartrim flying now with this arrangement? If so, how long? Thanks!

I wonder if squaring off the back of the cowl at the air exit would help cooling... creating a vacume to suck air out of the cowling helping more go through the NACA duct. Oh... and a really cool spoiler!

YES I DID! Thanks for the response. I'm trying to sort out the details of a few last decisions while I get the building area in the shop (ie: the corner of the garage the GIB's stuff does not occupy) ready. Whether to use the NACA duct or the P-51 duct seems important now, but may be less important later when I get my hands dirty and see if it is easy to make the change. I hope you do prove him wrong! The less drag the better. After I made this thread I surfed around for "NACA aerodynamics". Not much about aircraft, but alot of information and pictures of 200 MPH racecars. Can you believe that all of those rear-engine cars use NACA ducts feading directly into small radiators? Millions of dollars in aerodynamic testing flushed down the toilet! Wait, I see a forced air scoop... no, that feeds the airbox. The pursuit for knowledge continues! I'm still toying with the idea of 2 rotaries powering twin duct fans blended into the body...

This probably should be in the egine area, or could be in another area related to aerodynamics... but here goes. http://home.earthlink.net/~rotaryeng/how-to-cool12.txt This may be old... but its news to me! It seems to say that an NACA duct with an obstruction inside (like the radiator) won't work well because of external diffusion (air in the duct gets blocked, air coming from behind goes around). I goes on to state that the P-51 type scoop off of the boundary air layer ala Bulent (sp?) works better. John... do you have any thoughts on this since is specifically discusses cooling a rotary? I was curious to see what arguments dispute this thoery. I know about the vortex generators ahead of the NACA but that seems to be more of a crutch than a solution. But I'm not a big fan of creating more drag with a scoop either... decisions decisions.

I for one am in love with the design... not just the sharp looks but the economics as well. I could fly first class the remaining years of my life for what most high speed aircraft cost. I can't justify the expense. When I go to the airport and see what people are spending to cruise at 120-160, or see one of those aircraft sitting back in a corner of a hanger, parts everywhere, waiting for the owner to finish the paperwork on his second mortgage before the mechanic finishes the MOH... I ride off on my motorcycle thinking I can't wait to hear the reaction when I finally get my $50k 220 mph glass arrow built and moved to my small town FOB/General Store/Gun Range. That said, I think many of us are always interested in improvements, no matter how great the designe may be. A little competition is the mother-in-law of invention.

... and in pusher configuration, your less likely to get sucked into the prop while fiddlin on the engine getting a bump on the noggin.

Your right Norm... sorta. Given two aircraft generating the same total lift at the same airspeed, the canard will produce more induced drag than a conventional tail. This is because the canard is responsible for generating some of the total lift of the aircraft and induced drag is a factor of lift. So, I can see how a canard wing will generate more drag than an elevator on a conventional tail. But taken together as a whole the main wing of a canard is assisted by the lift of the canard, whereas the wing of a conventional aircraft must lift both the weight of the aircraft and the downforce of the tail. He mentions the "relative inneficiency" of the canard. Isn't efficiency dependent on the design of the canard airfoil? Is there a high AOA for stall or something else inherent in the configuration that good design can't overcome? Just curious. Maybe you could prod the Phd for more details.

DUST! No wonder I haven't seen you lately... you've been hiding out over here in the engine discussion area. And I see you are making new friends! I'll throw in my 2 cents and maybe take a little heat off of you! Continental: don't listen to the ridicule, stick with what your comfortable with. Some of us are going for new technology. That's their choice, that's a choice I'll probably be making as well. But for all the talk about reducing failure points by eliminating valves and cam shafts, we introduce new mechanical failure points with water cooling and PSRU's. To borrow a phrase from No. 4, glug glug glug hicup fart bang hello trees. We all weigh what we get, what we loose, and we place our bets on the horsepower of our choice. One thing that can't be disputed (although I'm sure someone will try) is that the Continental has many proven reliable hours in the design... that's how you get to be old. TURBO: What is the compression ratio of the engine? Most of my experience has been with automotive engines (another reason I'm leaning toward an auto conversion) but the principle should be the same. Above 9.0 to 1 and you could have tuning problems (lookup "Hanger Queen"). I've had an engine with 10.7 to 1 with a big honkin turbo, so it is possible but it can be cantankerous. Below this and an engine can swallow the extra air fairly easily without throwing up... Intercooling: Must have item. Easiest way to squeeze more efficiency and reliability out of a turbo engine. EFI/ETI: I too suspect Tracy knows what he is doing. What hasn't been mentioned about mapping is that it is usually not 2 dimensional. The computer doesn't just read RPM to decide how to go squirt bang... most computers now read other variables like OAT, EGT, boost, load, et al. (And that's just the computer in my wife's oven!) Even if some of these inputs are removed (like real time EGT), the original mapping is based on these inputs. Tracy can tell you what inputs the computer needs to derive the information it needs to use the proper outputs. Shock Cooling: This is a problem you'll have to live with no matter what you do to a Continental (or Lycoming). Overhaul $: well... you didn't really ask that question, did you?

Speed at a given weight and HP _IS_ a form of efficiency. Fuel economy is another. The theory involved in comparing two different designs is complex and cannot be simplified below "BLAH BLAH BLAH" levels. Maybe this is just beyond your grasp...

Yes the retracts add significant speed, yes a CS prop adds cruise speed (even a cruise fixed is still somewhat compromised to reduce cavitation on take-off), but I think everyone is missing a big difference between the two aircraft. Take a close detailed look at the Lancair fuselage nose to tail... then look closely at the Cozy fuselage. Then visualize what is happening to the air around them at speed. The Lancairs are made in huge molds that can be designed for perfect streamlining. Now I'm not knocking the Cozy, but the tub is a bit squarish. Creating the perfect aerodynamic shape without molds would be a killer for us to build... so it's something of a compromise (I'll trade 10kts for 2000 extra build hours or $50k in prefab structure prices any day). All things being equal, the Canard design with twin lifting surfaces are more efficient than one lifting surface and one drag generating surface. But things here are not exaclty "all things being equal".

He's replacing the back seat with an extra fuel tank... I still don't think he'll get 1000 miles out of it.