Cozy or Open-EZ?

[mfryer]

I'm a software guy so I built a database of all the parts I need for the build. I then build some queries so I can pick which chapter I want to order for. My query then reviews the pricelist from ACS & Wicks to find the best price and then creates an order to each for optimum pricing.

Would you be willing to share the database?

[TMann]

Sure.....It's in MS Access and I noticed today the Wicks changed their prices.

My entries are for a Long-EZ(type E:D ) but yeah....I'll make it available.

[karoliina]

What reports would those be?

 

It looks like propably some people have mixed mph and kts and I have interpreted the numbers as kts where they were mph.

 

My dead stock COZY (aerodynamically and structurally) stall speed, at mid-weights and mid-CG, is about 72 MPH, or 62 KTS. At 2150 lb. and full forward CG, the stall speed is about 80 mph, or 69 kts.

 

That sounds like reasonable number. Ok, looks like my basic assumption was wrong. I went to check the cafe report and indeed it stated that the bobbing started at forward CG at 68 kt. So hereby I stand corrected. Thanks for correcting me.

 

With respect to your red herring about 4000 ft. runways, I operate out of a 4000 ft runway that's at 4000 ft. elevation. I've taken off of this runway at Max Gross weight on a hotter than standard day - DA was about 5000 - 5500 ft.

 

That was based on the specs given by the Finnish Cozy Classic -flyer (which may be incorrect or inaccurate):

- He uses approach speed 110 kt which is as fast as some passanger jet. I have witnessed that once on board of his plane. It was so fast that I have never been that fast landing on any light plane, e.g. RV-8 used 82 knots as approach speed and it was considerably slower.

- 6000 feet runway gets really short

- He once attempted landing on 3000 feet runway and his comments are basically that "never again"

- My home airport has 4000 ft runway and he don't attempt landing there because he says that it is not possible to land & take off safely from there because there is a obstacle at the end of the runway which makes the usable runway length so much shorter that he just can't make it safely. There is a hill, trees and houses at the end of the runway. On the other end there are several houses, small elevation, high current power lines and pretty tight turn to right to avoid getting out of the pretty small airspace reserved for this airport.

- The 2700 feet airfield in Lapland which is one of my favorite places to fly, is completely out of question according to Rauno (elevation 738 ft) even as a solo/light weight.

 

So what I could conclude from that:

- The Cozy Classic in question has something wrong with it, w&b, aerodynamically or otherwise

- Or it is flown at improperly high approach speeds

- Or I am totally confused and don't know what is correct and what is not.

 

I see that the selection of examples I have evidenced is too narrow to draw any conclusions. Maybe I should get on somebody else's plane and see a different view that way. And demonstration of landing & takeoff with forward CG with full load to a 2500 ft runway would really change the whole perspective - the majority of small airfields happen to have runway length 2500 ft - 3000 ft and they are rarely larger and there are often obstacles in form of tall trees in both ends of the runway. Being restricted to only the handful of the large airports would reduce the versatility quite a bit in this country and also add cost by landing fees, parking fees, taxi tickets etc.

 

Things would be so much easier if there would be a lots of large airports around and if one could rent a car from any airport, but that service in general is not very often available except on the Helsinki-Vantaa airport that I do not use anyway (the GA traffic fees are very high on that airport and quite large amount of the days it is closed from GA alltogether). The small airfields add the possibility to go to camping and with the large airports, the vacation would be rather a hotel-vacation only at the handful of biggest cities which by definition is pretty boring in this country.

[TMann]

Karoliina......That's what the forum is for. Obviously you have experienced a performance envelope that deviated from the design. Anyone can land hot and skew the passenger's perspective.

 

Now you have some additional information to work with.

 

For the sake of the forum, it would be nice if counter-views could be delivered with a bit more grace and consideration.

 

T Mann

[Marc Zeitlin]

That was based on the specs given by the Finnish Cozy Classic -flyer (which may be incorrect or inaccurate):

You've mentioned this guy before, and it always struck me that he's clueless and flies his aircraft completely incorrectly.

 

- He uses approach speed 110 kt ....

No wonder he needs long runways - I float a mile if I come in that fast. That's totally absurd.

 

- The 2700 feet airfield in Lapland which is one of my favorite places to fly, is completely out of question according to Rauno (elevation 738 ft) even as a solo/light weight.

Nonsense. Solo, lightweight, you're off the ground in 1/2 the runway. Landing is no problem whatsoever - I'd have no compunction at all about flying in there, even relatively heavy (although probably not at MGW, but 3 folks and 1/2 fuel would NOT be a problem).

 

So what I could conclude from that:

- The Cozy Classic in question has something wrong with it, w&b, aerodynamically or otherwise

Possible, but unlikely.

 

- Or it is flown at improperly high approach speeds

Absolutely.

 

- Or I am totally confused and don't know what is correct and what is not.

Doubtful. You've been fed a line by someone that doesn't know their ass from a hole in the ground, and that's the only datapoint you've got. There are folks in the US that fly their canards way too fast on landing too, although I've never heard anyone say they approach at anywhere near 110 kts.

 

If you're still interested in the COZY, stop by the next time you're in the US, anywhere near LA, and I'll be happy to demo the plane CORRECTLY for you. If I make it to RR this year (I'm hoping to) I'll be happy to show you the performance of the COZY off of a 3K ft. runway.

 

And demonstration of landing & takeoff with forward CG with full load to a 2500 ft runway would really change the whole perspective...

MGW, full forward CG will require more than 2500 ft - I'd use 3K ft as a minimum at std day SL. But MGW REAR CG would probably be doable. But unless you're going for a 800 NM flight with 3 large folks (two of them VERY large in the front), you'll never be at MGW full forward CG.

 

- the majority of small airfields happen to have runway length 2500 ft - 3000 ft and they are rarely larger and there are often obstacles in form of tall trees in both ends of the runway.

While that's certainly not the optimum airport for a COZY, as indicated they're doable. You'd need to think about the situation, and you'd probably need to ensure a rearward CG and 1/2 fuel, but that's hardly a showstopper, if the OTHER performance of the plane is what you want.

[Jon Matcho]

For the sake of the forum, it would be nice if counter-views could be delivered with a bit more grace and consideration.

Marc's reply was succint and to the point with factual data, and while Karoliina may not care for the 'tone', looking beyond that she should appreciate the input as much as I do.

 

I've said it before: Marc can virtually punch me in the face any day (it never really hurts). He's the real deal and I truly value his contribution to the community. You can listen to other blithering idiots who's online persona may appear more gracious, but I personally don't consider the exchange here between Karoliina and Marc requiring anything more. Building and flying airplane's safely should not require touchy-feely stuff. I've learned to not be offended, but some don't seem to manage.

 

Now the Finnish fellow may have an issue at this point, but then again, maybe he NEEDS to read this thread.

 

Moral of this story? Know that throwing numbers around will attract Marc guns a blazin'. (I saw that coming a mile/km away )

[TMann]

Yes, I agree, Marc is a very knowledgeable source and I appreciate it when he shares information in a concise manner.

I do however observe that some exchanges have been rather caustic and do not contribute to a welcoming environment for people who are genuinely starting from scratch and trying to learn.

 

It's all about communication. I just would hate to see the value of the information delivered diminished by other distractions.

[Marc Zeitlin]

As a followup to the COZY performance questions, I flew today for an hour. I took off and landed twice. I was solo, full fuel, for a Gross Weight of ~1650 lb.

 

The takeoff at Tehachapi, DA=5000 ft., took approximately 1500-1600 ft. When I landed at Camarillo, DA=~1000 ft., I used about 2500 ft. of runway, because I didn't feel like stomping the brakes - I could have turned off 700-1000 ft earlier if I felt like it. I indicated 90 mph on short final (78 kts). and touched down at about 75 - 80 mph.

 

The takeoff at Camarillo, same DA, took about 1100 ft. (30 lb. lighter, due to 1/2 hour of fuel burn). The landing at Tehachapi took about 2000 ft.

 

This should help put things in perspective. Obviously, forward CG's and heavier weights will decrease performance and require longer runways. But unless you're going to be in the air for 5 hours, you don't need full fuel, and you can arrange the aircraft to have the CG as far back as possible.

[TMann]

This should help put things in perspective.

These are excellent, factual numbers to consider when considering a Cozy.

Do these numbers inprove with an adjustable prop?

[Marc Zeitlin]

These are excellent, factual numbers to consider when considering a Cozy.

Do these numbers inprove with an adjustable prop?

One would assume that with a properly designed CS prop, the takeoff #'s would improve, yes. I have a fixed pitch prop, optimized for cruise. A fixed pitch prop optimized for climb would also improve these #'s.

 

Landing won't be perceptibly different from a roll standpoint, although putting a CS prop in flat pitch at low throttle setting will increase the descent angle (more drag).