Marc Zeitlin

Could someone explain the design concept of the swing-wing canard on the Beech Starship?

I'll bet someone could.

Apart from being speed related, what was the primary relationship with the aerodynamic function of the canard?

 

To meet the FAR landing speed requirements, the Starship required flaps on the main wing. Flaps substantially change the moment coefficient of the wing, and to counteract the extra nose down moment of the main wing, the canard needed to be further forward. The swinging forward of the canard was coupled to the flaps on the main wing - when the flaps were deployed, the canard swung forward, moving the center of lift of the canard forward. This kept the lift/moment balance of the aircraft correct.

 

It's not "speed" related - it's flaps related. Now, you only deploy flaps at relatively low speed, but no matter what the speed, if the flaps weren't deployed, the canard doesn't move.

 

The mechanism is extremely complex.

 

The patent # is 4,641,800.

 

Interestingly enough, while poking through the patents, a derivative patent for a SLIDING canard is presented by a "John A. Lockheed", in 1989, that uses a COZY III as the basis for the figures. The figures are reasonably explicit as to the workings. Whether this aircraft was ever built, I have no clue - I've never heard of it or seen it. The patent # is 4,848,700.

How do you go about logging your build time.

You write down whatever you like.

 

whats required for airworthyness inspection by the FAA.

Nothing. The FAA couldn't care less how much time you spent building your plane.

 

whats included in the times? is it the time taken to lay up the part or the time taken to lay up and cure. If it says 500 hours to build could you say 10-20% of that is cure time for the fiberglass.

Since the FAA doesn't care, you can write down anything you like, and claim as much or as little time for whatever you do.

 

Also does the hours and hours behind this computer reading post count. haha.

Sure, and write down the times you spent eating lunch while staring at the plans, too.

 

The only thing the FAA cares about is whether it was built for "education and recreation", that the "majority" of the aircraft was built by the builder(s), and if you want the "Repairman's Certificate", that you can show that you were one of the builders and are intimately familiar with the aircraft.

 

Feel free to log anything you like.

.... Do canard pilots think about the prop being really close to the ground on touch-down?

Would thinking about it change anything?

 

From the pictures of different canards I've seen landing, it seems the prop is only inches off the ground...meaning any slightly nose high approach could be disasterous. Could someone that flies canards a lot speak to that?

The aircraft is designed with a maximum recommended propeller diameter. Assuming that you do not put a propeller larger than that on the aircraft, and that you fly within the recommended CG range, the only way that you could touch the prop tips to the ground during a landing is by performing a hard carrier landing while at a very high AOA.

 

I have only heard of a one COZY MKIV flyer that has ground 1/4" or so off his prop tips in a hard, high AOA landing. I'll leave speculation regarding how he managed to do this to the peanut gallery.

 

So, the answer is, no, we don't think about it, because there's no need to. Unless you screw up pretty badly in multiple dimensions, you won't touch the prop.

I am rather certain that the Opus-3 is a modified Cozy III (original Cozy, possibly a Cosy Classic) with the only main difference being the canopy and chopped longerons.

According to Kai Christensen, the owner/builder, it is NOT based on a COZY, but a L.E. derivative.

Hi Mark,

Marc

 

$100 bucks and some sweat equity sounds great. How many yards do you think it'll take to make a cover? 6?

Dunno, I'm not a seamstress, but if I were to guess, I'd say 6-10, depending upon how you laid it out. You can get 60" wide Sunbrella for about $20/yd, and you could do the whole fuselage with 6 yards of that. You'd need about $10 worth of snap buckles and straps, so that's what - $130 or so (plus a spool of heavy duty exterior thread).

 

It would be nice if there were some public domain patterns.

Making the pattern is pretty trivial. Carl Denk describes how he made his cover (not sunbrella) in the COZY archives. Go to a show, find someone with a cover, and look at it. Not rocket science.

I think the DVD was made available on the COZY mailing list for a few bucks to those interested.

The 2004 presentation was filmed by Mark Beduhn, who is an amateur filmmaker.

 

It's an hour of video, and I'll see about converting it to an MPEG file for download.

You should do no such thing. I have to say, the lack of respect for copyright protection on these fora are, IMNSHO, deplorable.

 

The DVD was filmed and is owned by Mark Beduhn. If someone wants a copy, they should contact Mark and see if he has any more copies to sell. As of 8/4/2004, he was selling them for $15 including S&H.

 

As far as suggestions for the presentation, I asked: "Please reply directly to me via email at the address below - have at it." Posting suggestions here is not the optimal way to get your opinions heard, and your suggestions done.

We.....

The Imperial "we"? You have a mouse in your pocket? :-).

 

.....have also added a new Designs & Modifications section where everyone is encourage to post ideas and pictures of their mods.

The only thing that I would encourage, when publicizing modifications to proven designs, is that IF the mod could in any way affect safety, that people include information as to whether this modification has been proven on a flying aircraft, and if so, how it was tested.

1. How do these composite aircraft survive in a tie down situation, what are the issues?

Fine. I had my COZY tied down for 3.5 years in Massachusetts, with rain, snow, heat, etc. No problems, as long as you haven't painted it with something stupid that deteriorates with UV exposure. These planes do leak like sieves, though, so you do want a cover.

 

2. If this is viable, I’ve seen covers on the net and wonder if anyone knows of these or has an alternative?

I have a full cover (nose to spinner) from Dorothy Dickey, but I don't think she makes them anymore. Get a good quality "Sunbrella" or equivalent cover - it'll last you 3-5 years, easy, and if you've got a good sewing machine, you can fix the small rips/tears/seam issues. You can buy a LOT of covers for the cost of a hangar. Since MA got snow, I made myself some "socks" for the canard, as well, and after doing that, figured that I could have made the whole cover for about $100, buying "Sunbrella" on the web.

 

OTOH, the L.E. covers that Bruce's makes look great, especially with the wing extensions, if you don't mind spending the $$$.

 

I currently have the plane in a hangar in Tehachapi, but that's only because I'm splitting the $275/mo. cost with a co-worker, who's building a plane in the back.

I bought a Skyflight digital EGT. Have misplaced the directions

on hookup. The listed phone number is wrong. They have/had

a street address in Portsmouth, NH but I have not written to them

yet.

 

Can anyone tell me how to find them by phone?

 

Thanks.

See:

 

http://www.kitplanes.com/directory/supplier/instruments.phtml

... Since the cores can withstand up to 140F, we can heat tent our parts to 100 - 120F while curing under the bag (or NOT in a bag) if desired with no problems....

After some prodding from Wayne Hicks, I did a bit more research to figure out where I got that 140F # from.

 

Wayne wrote to me:

>----> Reading chapter 25, room temperature cure epoxies soften and lose

>rigidity at moderate temps. (160F.) Foams soften and swell at moderately

>elevated temps. (250F.)

 

That sure is what it says, doesn't it. For some reason, I thought that I had read that the wing foam had lower temperature capabilities. In fact, the Dow web page says that Styrofoam Brand Insulation's maximum continuous operating temperature is 167F (75C). Most of the "Last-a-foam"'s have a max. cont. service temp of around 200F.

 

I'm not sure where I got the 140F from..... Aha - close. From,

 

http://www.netcomposites.com/education.asp?sequence=47

 

the max cont. op. temp. of some PVC foams can be as low as 120 F, with processing at up to 150 F.

 

So, Nat's probably not being conservative enough if folks would use his #'s for fabrication temps.

 

At any rate, as long as you're not cooking your layups, either while bagging or not, you're extremely unlikely to harm the foam.

...Think about it, the foam is a ready supply of air to bleed into the layup. It might be closed cell, but I'm sure even a slight vacuum could coax quite a few bubbles out of the foam to make layups too dry.

 

Thinking back to the Cozy Girrrls demo at Oshkosh, the NACA scoop that they used was a solid, non-reinforced layup. Basically, an open mold. This is what vacuum bagging is traditionally used for.

 

Also, vacuum bagging is used to squeeze pre-preg onto core material like Nomex honeycomb in autoclaves. As mentioned, our core material will crush at those vacuum levels, and also they won't withstand the heat.

First, I'll say that I'm not a big proponent of vac-bagging for our aircraft - I just don't believe that the slight weight savings justify the extra work. Others disagree - that's fine.

 

However, foam cores of the types that we use in our homebuilt aircraft are used regularly with wet layups and vacuum bagging, at the vacuum levels that Steve has indicated. Since the cores can withstand up to 140F, we can heat tent our parts to 100 - 120F while curing under the bag (or NOT in a bag) if desired with no problems.

 

With respect to pulling air out of the foam and into the layups, there is no evidence that this happens. Measurements have shown good epoxy/glass ratios in foam core vac-bagged layups using standard techniques. In fact, it's FAR easier to get a quality sandwich layup using foam, micro, and a wet layup than it is with honeycomb core, which is a real PITA.

 

This is all for wet layups - pre-pregs are an entirely different story.

 

So, if you're willing to do the extra work for whatever weight savings there MIGHT be, don't be worried about these issues - there are enough issues to worry about :-).

... So at low speeds say 40knts I'm guessing here. I don't know the spring rates yet. Lets say 40knts and below, You steer with the tiller as speed increases we get light on on the nose, so now we are into rudder steering is that right?

OK, so once you've decided that the steering can be overcome with large enough forces, and will only be used at relatively low speeds, what's the advantage? Any large crosswind on takeoff at low speeds will require more force than the springs can provide, and you'll be castoring. I think that you'll find that if you set the springs appropriately, you'll essentially be castoring almost all the time, and steering only at very los speeds and very low turning angles.

 

Plus, the steering can never have the throw of a castoring wheel, so your turning radius when steering will be much larger than your turning radius when castoring.

 

We're not talking about heavy iron here - it seems as though small GA aircraft are moving away from steerable nosegear to castoring nosegear. There's a good reason for that - it's lighter, simpler, and works at least as well.

 

So, yes, your system can certainly be made to work - of that I have no doubt. It will weigh a bit more, and it will be more complex, but it can do what you propose. I just don't see where any advantage is to this combined system.....

..... I apologize for jumping down your throat and insulting you..... I'll see you at Oshkosh.

Accepted, and if I made you feel that I was attacking you with my responses, I am also sorry - that was not my intention. I'll be happy to discuss this with you in person at OSH, if you like.

 

I'm not sure where you got 120mph though. can you help me with those numbers?

Sure. Let's say that you're either taking off or landing at a high density altitude airport, and you're relatively heavy. Your IAS on final may still be 90 - 100 mph, but at 6685 ft. altitude, on a hot day (say, at Durango, CO in the summer, like when I landed there last August with my wife, tons of baggage and full fuel), the density altitude will push 10K ft. That means that as you touch down (or rotate) at 100 mph IAS (which, in the COZY at gross weight and mid CG, is about the speed I needed to begin a climb), your TAS and GS, with no wind, will be about 120 mph. These speeds are realistic for LE's and COZY's - many canard drivers land even faster than this, although I'm not sure why.

 

If you have nosewheel steering coupled to the rudder pedals, then as you attempt to maintain directional control using the rudders, you'll also be adding nosewheel steering inputs. The nose gear needs to be able to handle those loads at those speeds (and all lower speeds). These forces can be substantial as velocities get higher than walking speed. If you set the castoring breakaway so that it will castor at low enough forces so that you don't overload the nose gear and attach points at these speeds, then the question becomes "what is the nosewheel steering doing for you"?

 

Make sense?

Thanks. Do you know where can I get the performance data of those airfoils?

Nope. Not unless John Roncz kept the data (or Beech did). If the UIUC database doesn't have them, you'd have to go to the source.

Hi all.

 

New here. Not a builder. I Need to know which airfoil does the beech starship uses. I've been looking around the net but cannot find any info except that it was a natural laminar flow airfoil.

The best you're going to get is from:

 

http://agert.homelinux.org/~fredrik/flyg/aircraft.html

 

which indicates that both the canard and main wing airfoils were custom Roncz designs - a Roncz 1085 on the canard, and Roncz 1107 on the main wing.

.... What makes you think the people you are addressing are laymen.? This is an open forum you know, or are you the only engineer in the world?

Most folks are not engineers (either school taught, or self-learned). The safe assumption to make is that the folks we're addressing are laymen.

 

Why do I need to steer at 120mph I'm sure you insisted that there would be no need to steer our aircraft after 40mph because our rudders where sufficient for steering so which is it engineer? 120 or 40

YOU will need to steer at 120, because YOU will have nosewheel steering on your plane, and YOU will touch down at 120 mph GS every once in a while. _I_ will only have to steer with something other than the rudders below 40 mph, although I have the capability of doing so with the brakes as well. If YOU attempt to steer with the brakes at your 120 mph touchdown speed, you will put a very large side force on the nose gear. If you put in springs that allow castoring with any substantial amount of force on the nose gear, then you will have defeated your nosegear steering purpose.

 

Maybe you should think these things through before throwing the insults around when someone points out facts to you.

 

All I was asking for initially was some feedback on the drawings...... Not all this other happy HorseSh*$ I got in response. Good LORD!

So, someone other than you (cybersushi) starts this thread. Then, someone other than you (airwrench) posts a statement to which I responded, saying NOTHING about your particular design. You then take it upon yourself to assume ownership of the thread, as if no one else has a right to respond on it unless they get your approval, and you think that it's YOU that are getting happy horseshit?

 

You don't know the history of the design you're building, you don't know what modifications have been attempted and/or discarded by other folks before you or why, you think that you're the only one that has the ability or drive to complete this particular modification, you admit that you insult me without knowing MY history, you DON'T address the valid issue of other aircraft that have castoring nosegear, and you think that I'M full of myself?

 

At least I realize that I don't own this forum or thread, not to mention drive, ambition, and capability, and that everyone has a right to have their say, whatever it might be.

 

Listen, Tony. You're obviously a bright guy, and you're attempting some pretty interesting stuff with your airplane, even if a lot of the changes seem to be for the sake of change alone. But I hope you succeed, because it would be cool if you do. However, jumping down people's throats and insulting them because they write stuff you don't want to read isn't going to help you any.

J... Guys like Marc have there place in this world. We need the nay sayers to keep the fires lit. God knows without guys like Marc we surely wouldn't be flying airplnes right now, the Wrights Bro.s would've just given up.

Actually, the Wright's were far closer philosophically to my position than to yours. They studied the existing theories, developed their own, tested everything they developed, and attempted to come up with the best, most efficient solution they could using the technology available to them at the time. They did nothing just so that they could be "different". They were engineers in the best sense of the word - they were NOT laymen, by any stretch.

 

With respect to your nosegear, as soon as you have it built, mounted on your airplane, weighed, and tested to 120 mph on the ground, and it weighs less and works better than a castoring nose gear, I'll be happy to state publicly that you've come up with a better mousetrap. Until that time, it's hardly reasonable to state that your two drawings are an example of working steerable nosegear for a flying canard aircraft, any more than it's reasonable for Infinity to state it for their design. There are over 2000 examples of working castoring nose gear on canards - I was looking for ONE example of working steerable nosegear on canards. Can you point me to ONE?

 

With respect to your attempted insults, I have almost never said "it can't be done". Almost ANYTHING can be done - the only things that can't are those that defy the laws of physics, which steerable nose gear certainly doesn't - the question is whether it's useful, reasonable, economical, or smart to do so. I was merely addressing airwrenches astonishment, when you stepped in with your insults and objections to reality.

 

You haven't addressed the issue as to why Cirrus etc. have gone the castoring route. Are they all stupid, Luddite, anachronistic, neanderthal naysayers like me, too?

 

I suppose I got my current job just so that Scaled could say that they had one idiot working for them - kind of an equal opportunity thing going on.

Says who? You?

Says all the folks that haven't bothered to implement (or attempt to implement) the modification.

 

That would hardly indicate that there aren't ANY out there. MARC

Point me to ONE, please.

 

So what is your point on this one? Maybe they're too busy building mains.

My point was:

a) It's non-trivial

b) There's no demand

 

Could it be, just maybe, the takeoff distance on these airplanes might be a little shorter if you weren't tapping the brakes all the way down the runway or even halfway down the runway?

Sure. A little shorter, maybe. But if you review aircraft with similar performance (Glasair, Lancair, etc.), you'll see that the TO distance is not substantially different. Most of the difference (if any) can be accounted for by the fact that our aircraft are canards (which intrinsically have longer TO distances), rather than that they have castoring nosegear.

 

Would that not be a good enough reason to have some steering capability?

It might be, if there weren't perfectly good techniques that didn't require nosegear steering and it's associated complexity and weight to compensate.

 

Not to mention maybe extending the life of a brake pad or two.

So, you'd rather greatly increase the complexity, weight and cost of the nose gear, instead of replacing $50 brake pads at the conditional inspection? I can buy a LOT of brake pads for the extra cost of the heavy, strengthened nose gear you're going to need to steer.

 

How about tire wear? What about brake failure at 38kts? Before your precious rudders are effective.

The tire wear difference is inconsequential. Brakes fail, steering fails, nothing's perfect.

 

Who said anything about steering at 90kts?

airwrench. Go back and read his posts.

 

The brevity of your negativity is stifling MARC.

I said nothing about the IDEA of nosewheel steering until airwrench stated that he was "astonished" that no one had dealt with this critical problem in the 30 years that these planes have been flying. If folks want to experiment with modifications that they think will work, more power to them, if they've done enough investigation and analysis to indicate that they can do the modification safely.

 

I was trying to point out that there is no "problem". There are many ways to skin a cat, and castoring nose gear (as shown by the many aircraft, some of them very new designs, that use this technique) is one of them, as is steerable nose gear. Each has pros and cons. Given what seems to be a move (by Cirrus, Diamond, and Columbia [Lancair]) to castoring nose gear away from steerable nose gear, I'd say that the engineering tradeoffs probably favor castoring. Unless, of course, you know more than all the engineers at these three successful aircraft companies.

 

I can't wait to see this. I'm sure everyone including myself will walk away with the feeling of enlightenment by, "Nothing will ever work, don't try anything new, don't question the plans", Marc J Zeitlin. I'll be the first in line at that forum

Funny guy. You've obviously been paying no attention to the 11 years of arguments that I've had with Nat Puffer regarding various modifications to COZY's, nor the engineering analyses that I've done either supporting or not-supporting modifications, as the facts dictate. But hey, don't let facts stand in the way of your opinions - few others do. I've got modifications to my plane, and I've supported others with modifications to theirs, when it's warranted by analysis and testing. However, when someone claims that there's a DESIGN DEFECT with these aircraft when there isn't, I'm going to say something.

 

I think having an objective, balanced view of any particular proposed modification is far more likely to result in success if the mod is attempted, or in a successful decision to not attempt it.

 

Can't wait to see you there. You'll know it's me because I'll be heckling you out the door.

You are welcome to attend and ask questions (or answer them) just like anyone else. You're hardly the first person to object to my pointing out that they don't have a full understanding of the subject of the discussion that they're engaged in.

Nearly astonishing that no one has addressed this issue with diligence until now......

Why is it astonishing that no one has "addressed" an issue that doesn't need addressing? Infinity has been threatening nosegear steering in their canard for over 10 years, but that's gone nowhere. If there are any canards out there that have installed nosegear steering, no one I've ever talked to has ever seen one. There's a reason for that - it's like trying to exterminate all the giraffes in Alaska - it's really not a big problem that needs addressing.

 

perhaps differential braking is a hard habit to break????

Have you ever flown an aircraft with differential braking, like a L.E., V.E., COZY, Katana, Cirrus, Lancair Columbia or a Grumman Tiger? It's pretty simple. I can spin my airplane in it's own length - try that with nosewheel steering. The ONLY issue with differential braking is taxiing (and the early part of a takeoff run) with a strong crosswind, but there are relatively simple techniques for dealing with both of those.

 

Full authority steering at speeds >90mph would be excellent, I am sure that soon it comes to be..........

I don't know what airplanes you rent, but if you think that you can do any amount of steering at 90 mph using the nosegear, rather than the rudders, you're fooling yourself. The COZY rudders kick in at about 40 mph, and differential braking (or simultaneous braking, as the case may be) works at ANY speed.

John Alexander not buiding yet but have plans in hand.

Well, come to OSH, get a ride, get yourself psyched, and get started!

I was told by someone that the Berkut has a higher airspeed than the Cozy. Does anyone know for sure?

Lots of people know for sure.

 

Yes, the Berkut is faster than the COZY.

 

Has anyone applied Berkut type wings on a Cozy to get greater airspeed?

The Berkut type wings are essentially identical aerodynamically to the COZY type wings. The Berkut is faster because it's a smaller aircraft with retractable gear with a larger engine. There's no magic.

Folks:

 

I am pleased to announce that Daryl Lueck and I will be co-hosting the COZY Forum at OSH 2006. We have not received the paperwork from Nat quite yet, so it's not clear what the day and time will be, but we'll announce that as soon as we get it settled with the EAA.

 

So, two years ago, when I gave the forum last, I gave a very general history of the COZY, it's benefits, some building info, and some personal experiences with the plane. Last year, Nat gave a very good presentation on canard/COZY aerodynamics. Both of these presentations can be reviewed on the COZY builders web site.

 

I've got a few ideas for things to talk about, but I would like to solicit ideas and requests from you all - what would you like to hear/learn/talk about, with respect to COZY's and/or canards in general? Info for prospective builders, info for builders, info for flyers, technical info, whatever - suggest away. If I need to do some research to address your issue, I will.

 

Please reply directly to me via email at the address below - have at it.

I don't, but there is a lot of metal in there. The gear legs are all metal, and there are metal inner workings with hydraulics. Guessing, I'd come in at 103 lbs.

What makes you think the gear legs are metal? I couldn't find a definitive answer, but:

 

http://www.berkut13.com/berkut15.htm

 

says:

 

"The first step was to micro fill, and primer the gear legs -"

 

You don't do that with metal legs.

 

And "103 lbs."? That's a strange number to guess.

 

If you do reference the online defintion of feel from Merriam-Webster, you will see that airwrench used the word quite acceptably.

From a semantic standpoint, sure. From a "make a decision regarding engineering data", uh-uh.

 

If the guy that designed my wing spars put as much spar cap material in it as he did because it "felt" right, I'd chop the plane up and never get in it again. Either the Infinity gear is as good as the Berkut gear from a drop test standpoint (and since Infinity has published FAA drop test results, and Berkut hasn't, I'd say that if anything, it's better) or it isn't. Having "feelings" about it doesn't change anything.

.... (kinda like the aesthetics of the infinity but I feel they would not deal with a hard landing as well as the berkut).......

I'm always fascinated when people have "feelings" about things like this. On what do you base these "feelings"?

The forum will be down for an hour within about 1 hour from now for software and hardware maintenance.

Speaking of maintenance, why'd you remove the Islamic screed? I thought it was just so applicable to canards.....