Jack Kretmar

Question for Cozy builders I have been following the forum for a long time and have a minor question. In looking at the various Cozy IV’s, I have never noticed any “auxiliary” NACA scoops for ventilation on the fuselage, and yet I keep hearing about them. Are these now standard features on the plane?

This thread may be a little off the subject of aircraft. In reading Marc Zeitlin's work profile, I see that he worked on a noise reduction project for the Bose corporation. Is this those new noise reduction earphones we hear about. If so, that's interesting because they would be great for the Cozy (even though they are very pricy). Is this the case, Marc? I'm no engineer, but I suspect they work by "reading" the noise signal and then instantly generating a reverse amplitude "mirror" signal to cancel out the noise. Do I have that right?

Jerry & Mike, thanks for the answers. That really helped.

In following the builders' websites, I had a number of questions.One, in particular, intrigued me. One builder, Rick Maddy, describes, in his Chapter 19, Step 9, removing 0.7" of foam from the outboard wing rib. I wonder how one manages to remove a uniform depth of 0.7 foam and create a perfectly flat planar surface at right angles to the wing skin? If Rick or anyone can answer this, I would appreciate it.

Greetings No. 4. Christchurch, NZ, eh? How are things in the islands down under? I see you are into unusual aircraft. Yes, we workrd on the Sea Dart. I understand the concept was to lower the craft into the sea from a ship. The hull floated. As the engine reved up and the plane picked up speed, the ski was slowly extended for hydroplaning to raise the hull. If the sea wasn't glass smooth, the plane would buck so sevearly, it practically knocked out the test pilot. That ended the project.

In regard to unusual canards, many years ago, I belonged to a group who restored World War II and post War naval fighters for display purposes. They were given some hanger space at the Willow Grove Naval Air Station outside of Philadelphia. At the time, we we worked on an experimental Navt jet delta wing fighter which had a retractable water ski. This design never panned out. One weekend, we were invited to visit the Paul Garber Facility of the National Airospace museum in Maryland. This is a large facility where planes are restored and repaired for exhibit at the museum. While there, we saw many interesting craft, including the Kyushu J7W1 Shinden (disassembled), the first Jet Bomber (German) and the Enola Gay (disassembled). It was an erie experience looking from the front, into the cockpit at the bomb sight. Apropho the Shinden, if they had managed to put a jet engine into this thing, I suspect it would have made one wicked air defence fighter. Anyhow, that's just my two cents worth.

Thanks for your point of view too, Rick Jack

Wayne, Thanks for the explanation. Jack

This question may have been asked before. Recently I had the opportunity to visit (and possibly supply a set of helping hands to) a builder who was assembling the tub. He had fabricated the sides and had done a great job. He used dabs of epoxy to hold the foam to the fiberboard and (as usually happens) took a number of chunks out of the foam when he popped the sides. My question is, when you use the drywall screws method, how do you reach under the jig fastened to the table to insert the screws? I beleive Wayne Hicks can best answer this but a reply from anyone would be great. Thanks, Jack

Location: Margate, NJ Posts: 11 Offer to help From Jack Kretmar, Gentlemen (and Ladies), For about two years now, I have been following the Builders Forum with great interest and occasionally shooting the bull with builders and asking annoying questions. I decided its time for a little less talk, talk, talk, and a little more do, do, do. While I’m not quite yet ready to build, I very much want to get into the process by helping someone else. Obviously, I have the selfish reason of wanting to hone my skills, so I’m looking for people who want some help. Please note that I not only like to observe but to work! I live in Margate City, NJ, which is on the same island as Atlantic City. The closer the builder is, the better, but I’ll consider anyone located in Southern or Central New Jersey, the Philadelphia area or Northern Delaware. O.K. people; the offer is on the table. Let’s hear from you. Jack

From Jack Kretmar, Gentlemen (and Ladies), For about two years now, I have been following the Builders Forum with great interest and occasionally shooting the bull with builders and asking annoying questions. I decided its time for a little less talk, talk, talk, and a little more do, do, do. While I’m not quite yet ready to build, I very much want to get into the process by helping someone else. Obviously, I have the selfish reason of wanting to hone my skills, so I’m looking for people who want some help. Please note that I not only like to observe but to work! I live in Margate City, NJ, which is on the same island as Atlantic City. The closer the builder is, the better, but I’ll consider anyone located in Southern or Central New Jersey, the Philadelphia area or Northern Delaware. O.K. people; the offer is on the table. Let’s hear from you. Jack

Jim, Thanks for your reply which answered my question exactly. The oil "problem" is no problem at all. I'll certainly join Tracy Crook's group. Jack

I'm posting this in the general forum. In aircraft conversions of the rotary engine, you have to add two-stroke lawn mower engine oil to the fuel. Can this make the engine burn "dirty", causing carbon deposit build-up in the combustion chamber and exhaust port areas? It is my understanding that carbon build-up can cause pre-ignition. Is this a factor, and if so, what can be done about it? Jack

I have a question about the aircraft conversion for the rotary. You have to add two-stroke lawn mower oil to the fuel. Doesn't this make the engine burn "dirty", thus causing carbon deposit build-up in the combustion chamber and exhaust port areas. My understanding is that enough build-up can cause pre-ignition. Does anyone have information on this?

Alright guys, Im convinced! Composite construction is strong and durable. Cheeze, the reaction of you cozy stalwarts is phenominal! You know; the very day I posted my question on the website, I caught a T.V. show on gliders and sailplanes. One of the craft featured was a super slick (in the literal sense of the word) composite sailplane that could go up to 146 mph. and do all kinds of aerobatics. I figure, any plane that can sustain those kinds of g-loads must be pretty strong. By the way "largeprime", I didn't mean to rile you up. I could just see the hair on the back of your neck, bristling from your indignation as you're thinking, "Who is this dufus to ask such a silly question?' Sorry about that. I like to ask lots of questions, and sometimes that irritates people. I'm looking for reasons to build, not excuses not to. Also Wayne, I was talking about your site. I'll bet you got some email from other builders, saying, in effect, "What are you trying to do? Scare this guy off before he's even built a bulkhead?" Seriously, I'm impressed with the ingenuity, know-how and diligence of all the builders. I'm particularly impressed with your site, Wayne. No offence to anyone else, but your techniques for building the tub and for lining up the wings and main spar together,answered a number of questions I had. But be assured that if and when I go with this, I'll be stealing ideas from everyone. Well, it looks like I'm rapidly running out of excuses not to build. Unfortunately, gentlemen, there's one that's not so easy to overcome, but I hope to remedy that in the future. And no, John. I'm not planning to take ten years to build this plane!

I,m asking this as a tyro who knows very little about the subject. A question came up as I was looking at a builder's web site. He mentioned the difference between urethane foam and Styrofoam and noted that the urethane tends to disintrgrate over time. What I want to know is; why not use Styrofoam for the whole aircraft, if it's more durable? Is there a weight penalty for using it? Is the urethane easier to carve for curved surfaces? A more general question is, just how durable is composite construction? I'm under the impression that it's like a composite surfboard, only stronger. Still, I'm wondering, with time, heat and the stress forces on the plane from G-loading in flight, will the foam substrate start to deteriorate, causing problems deep down in the core material, or delamination between it and the glass/epoxy skin, thus leading to eventual structural failure? I'd surely hate to invest many years of my life building this thing, to see it start to deteriorate after five years, becomming a threat to life and limb. I noticed in Nat Puffer's promo.video that Burt Rutan made a big deal out of the superior construction compared to conventional "tin cans". Maybe I'm being a worry wart about this, but what is the story on urethane foam and composite construction in general? I saw something about a destructive test being carried out on an older composite plane. Any thoughts on this would be much appreciated.

Regarding rotary engines, does anyone know the compression ratio of the following; a normally aspirated R13B, a turbocharged one and the new Renesis non-turbocharged one? What is it for a Lycomming 360?

Does anyone have any info on a Mazda RX-8 rotary engine conversion for the Cozy Mark IV ?

In regard to my two previous posts, does anyone know of any composite canard builders in the south New Jersey area. I wuold like to see what they're about, and offer some help, if it is wanted. Contact me at j.kretmar@att.net. Jack retmar

Am offering unskilled help to any builder of composite construction canard who is located in the Atlantic City, NJ area. Am seriously considering building a Cozy Mark IV, myself, but am looking for some prelimenary input and experience. Contact me at J.kretmar@att.net. Jack Kretmar

I have been following Nate Puffer Cozy IV, and also John Slade's website for some time and I'm seriously considering building a Mark IV Cozy. Before I organize the necessary space and get together the funds, however, I would like to learn more about building this craft by offering my unskilled help to anyone who lives in the South New Jersey area near Atlantic City and who is into this project. If anyone is interested, please contact me through the forum. Jack Kretmar