Landing Gear Geometry

[Spodman]

We just don't use that around here.

noisily and stubbornly defiant; "obstreperous boys"
boisterously and noisily aggressive; "kept up an obstreperous clamor"
wordnet.princeton.edu/perl/webwn

Would appear they use it at Princeton. Maybe we should have both paid attention at school.

And yes, sorry, this discussion has wandered a bit off topic. This reflects the integrated nature of the design of an aircraft. Move the main gear back you need more lift from the canard to get airborne in the same distance. Extract more lift from the canard you affect the stall characteristics. I would rather have my aircraft's tail (when I build one that is) hit the ground while parking or loading it then while flying it.

[tnt]

Originally Posted by Spodman

this discussion has wandered a bit off topic. This reflects the integrated nature of the design of an aircraft. Move the main gear back you need more lift from the canard to get airborne in the same distance. Extract more lift from the canard you affect the stall characteristics. I would rather have my aircraft's tail (when I build one that is) hit the ground while parking or loading it then while flying it.

Additionally, move the mains touch point on asphalt back and the amount of nose 'plop' on landing also tends to increase. That's one thing I noticed on my Cozy ride but I think that was due to too much weight in the front seats for the approach angle were were making. I was totally impressed by the amount of energy the nosewheel leg was taking as I was being lurched forward.

To be fair, the Velocity doesn't munch grass when parked. That would have to be due to the mains touch point on asphalt. But I too would rather keep the flight characteristics the Cozy now has.

[mdswitzer]

Originally Posted by Marc Zeitlin

Examples, please?

how about any SAAB made in the last 25 years - and there are several new business class canards & I know several of them will stall, I dont keep up on which is which since i cant afford one & I'm not being paid to do engineering on them

historically speaking there were several canards in WWI and a few developed before & after WWII & all of them stalled, of course they didnt have the understanding of aerodynamics we have now

Originally Posted by Marc Zeitlin

That's just patently false. The test pilot for ARES tells me that it has standard canard handling qualities with respect to stalling the main wing - namely, DON'T.

I know one of the individuals involved in writing military the test specs & I am 99% sure stall & spin testing were requred - I'd say 100% but I dont have access to those documents & without seeing them myself I cant say so

and i dont have to look at a notoriously inaccurate web encyclopedia to know what a deep stall is, I learned that in aero engineering classes 20 years ago

[ShaleDC]

Theoretically it would be possible to design retracting mains that could be hydraulically repositioned 3" to the rear after landing, so as to avoid lowering the nose.

But then, since partially lowering the nose achieves the same effect, I don't see much point, beyond just making the plane look more "normal".

[ShaleDC]

A better solution, in my mind, is to use a hydraulics & an oleo strut to adjust the firmness of the landing gear. On takeoff, make it VERY firm and elevate the AoA several degrees to aid rotation. On landing, reduce pressure to make it softer and nose down, less bumpy. When stopped, relieve pressure even more to drop the nose.

[SteveWrightNZ]

Originally Posted by Spodman

Mike Melvill has about as much experience of these things as anybody, I've read he recommends rocking the wings.

Ahh, when I was shown a fully-stalled wing, and told "ok, now add a great lump of down-aileron to the most stalled side", with which I was greeted with quickly accelerating blur of rotating blue and white, rapidly turning to also including flashes of green and brown. Of course, I wasnt familiar with this new modus operandus, so I shrugged at my instructor, who rectified the situation after struggling with it for some 35 seconds, and swearing quite forcefully at it, but he didnt appear that versed in it either. Actually, I did wonder for some time if he was swearing at the plane, or at me. Anyway, he looked a bit ashen so I volunteered to finish-up for the day, which was gratefully recieved. So I always take care not to abruptly pull a control surface when it is already stressed, and I would be tempted to not waggle a wing while it were stalled, lest it not wave but slap your ear hard, but hey, likely my inexperience is showing.

S

[Dust]

Until a member struck his prop I was under the misimpression that you would stall the canard before that was possible.

YOUALL say - become a better pilot - i say, tweak the plane.

Some of these planes can tip backwards - youall say - remember to keep nose gear down part way - i say - fix it

I am not a "become a better pilot" to solve what i feel is a design problem. an auto extend feature was offered for my nose gear - bought it.

I look at all of the changes made to these planes and see a very solid airframe that is stable and has great flying qualities despite all of the mods - youall say - it is perfect, change it and you will die.

heh heh heh

My eyes have opened up in the last few years, i've heard of a few prop strikes and if i have heard of a few, then there have been many more.

youall say - TOO MUCH takeoff distance if you move the mains back 2 inches, i say, raise the nose an inch to compensate, extend the elevators to compensate.

why not compare what i am saying to the 1 foot cozy extension, is there any.

on angle of the engine, my cowl will be loose around the engine, my object is to keep airflow smooth so i won't change the shape more that 7 to ten degrees, easy to tilt the engine to test thrust lines

So, i will fly with 340 in the front seat, changing the rears are gonna make the plane fly like it has 380 in the front seat? 420? 480?

BTW, Not a pilot

[Marc Zeitlin]

Originally Posted by mdswitzer

how about any SAAB made in the last 25 years - and there are several new business class canards & I know several of them will stall.....

We may be arguing semantics here - all these canards can stall the FRONT wing - it's the REAR wing that shouldn't be stalled. If you're referring to the Viggens, I'll argue that a delta wing aircraft on which the delta shaped canards were installed essentially to create vortices over the main delta wing is not exactly analogous to the Rutan derivative canards - the aerodynamics are substantially different.

Without at least a clue as to which business class canards you believe have the ability to stall their main wing and recover, and some reference for that belief, there's little to discuss.

Originally Posted by mdswitzer

historically speaking there were several canards in WWI and a few developed before & after WWII & all of them stalled, of course they didnt have the understanding of aerodynamics we have now

Again, which, and references for your belief?

Another thing to remember is that aircraft that have thrust to weight ratios that approach 1:1 have the ability to recover from attitudes and maneuvers that aircraft with thrust to weight ratios of 1:7 do not, since the latter must do it all aerodynamically.

Originally Posted by mdswitzer

I know one of the individuals involved in writing military the test specs & I am 99% sure stall & spin testing were requred .....

Whatever may have been required in military tests, the person who DID the ARES flight testing said that they NEVER stalled the main wing, and for the same reasons you don't stall a L.E./COZY main wing. If you'd like to argue with him about it, I can give you his phone #.

Originally Posted by mdswitzer

and i dont have to look at a notoriously inaccurate web encyclopedia ...

Actually studies have shown that Wikipedia is at least as accurate as the Encyclopedia Brittanica, for what that's worth.

Originally Posted by mdswitzer

to know what a deep stall is, I learned that in aero engineering classes 20 years ago

You're not the only one reading the responses here, or asking questions about deep stalls. If we were having a personal discussion, we'd do it via email.

[Marc Zeitlin]

Originally Posted by Dust

youall say - it is perfect, change it and you will die.

Can you point to ONE person or ONE posting where anyone said that? Either the "perfect" part OR the "change it and die" part?

Certainly there are certain SPECIFIC changes that could cause someone to state that "if you do that you'll have a much higher chance of something failing", but no one has said "change anything and you'll die". Not even close.

Setting up a ridiculous straw man just to knock him down doesn't accomplish anything for your argument.

Originally Posted by Dust

BTW, Not a pilot

Nor an engineer, or aerodynamicist, nor structural analyst, nor logician, nor .....

Do you really think that John Slade, Wayne Hicks, tnt, and myself are all idiots? I know you think I'm an idiot, but could ALL of us possibly be idiots at the same time?

[Dennis Passey]

I would add Richard Riley to the idiot list, Marc. You guys all have your heads up your behinds, collectively demonstrating you ALL are way to anal about this whole aerodynamic thing. NOT.
I WILL say it. I am not thrilled about picking Dust up in a bag somewhere..and I am not talking about small particulate matter- I am talking about DUST- the guy that writes his own book here on the design and what can be/should be changed on the Cozy Iv.
With each post, Dust, you seem to skewer another sacred design cow. Is this just your way of pulling our chains?
Please rethink your approach to this aircraft. YOU scare the he!! out of me with your attitude. Dang it if it isnt your own skin though.

[ShaleDC]

I fail to see how these personal attacks are addressing the question at hand.

[Dennis Passey]

Shale- Not an attack- I just wince as I read the entire string of posts and finally my fingers enter my reaction. Sorry.
BTW, Was fun at the Cozy dinner yakking with you all that time.

[Dust]

Originally Posted by Marc Zeitlin

Nor an engineer, or aerodynamicist, nor structural analyst, nor logician, nor .....

I know you think I'm an idiot, but could ALL of us possibly be idiots at the same time?

Correct I am none of those, but, I am fully capable of looking at the available information and making a decision. But, I like to look at all of the info, not just what I like.

Most of the information I have available to me is anecdotal.

this guy hit a prop, then we find out others have done the same! The original nose gear had weak teeth so in a bad landing with excessive shimmy, the teeth failed and the nose ground off a little, now the elec nose retracts are more robust so in the same situation, the bulk heads break. I have heard of 2 instances. I have modified my plane

I don't think you are an idiot, I think you are pompous and i think you have a few agendas that are opposite mine. You give out information to insult, not to educate. I barely read your posts as there is little to be gained, except bare tine morsels that can almost be used. I chuckle when you actually give useful info, like the radius of the fairing for intersection drag.

Now, instead of attacking me, why not look at the thoughts and ideas, instead of just dismissing them and deriding me.

I wish your email group had fostered discussion on improvements when i religiously followed it the first year or two of my build, I would have a slightly better plane. That is in my opinion.

It did not foster new ideas and in fact after a few years the conversations had become so routine and mundane that you even stopped archiving them as nothing new was being discussed.

Shortly after I started to support the previous forum, I talked to Nat and suggested that he not join as we were discussing various ways to modify the plane and I did not wish to cause him anger or frustration.

I highly respect Nat and consider him a friend and wish him peaceful, content years, not frustrating years.

You know allot but, sadly, have done nothing with it on your Cozy except change the brakes, buy aero canard strakes and one other item that escapes my memory for the moment. In my opinion your knowledge has frozen your ability to use it. Your mind is closed to any change as represented in your bird and your words.

As i learn the things that can be done to tweak the cozy it blows my mind that they were not discussed years ago, as they were known. Any such discussion was quashed

It aggravates me to find out you can get slightly better take off performance with an extended by one inch nose gear, better cross wind performance by enlarging the rudders (nats are 3" larger than plans - thank you drew) these are changes that are too late in the build for me. Not for others.

I will not be quashed and I will foster new thoughts and try my very best not to attack the person, just the idea.

[Dust]

Originally Posted by Dennis Passey

With each post, Dust, you seem to skewer another sacred design cow. Is this just your way of pulling our chains?
Please rethink your approach to this aircraft. YOU scare the he!! out of me with your attitude

how does this scare the heck outa you, moving the gear back 2 inches so the plane has better ground sitting ability. give up a little forward CG. Add a little canard authority when 6 inches was arbitrarily chopped off to get it back, add 1 inch to the nose gear to get it back. Test Forward CG take off performance on a

Runway 9L/27R
Dimensions: 7294 x 160 ft.

Remember - this is not a web site or personal email to people, it is an open forum where ideas can be explored and information gained.

My approach is to consider all the available information and then make up my own mind. My approach is to test and test and test.

my forward CG limit will be set by me after thorough testing, so will my rear cg, Vne etc., etc.

[Glos]

I don't think for one minute that anybody with any sense whatsoever is going to make the first flight testing the very edge of all the discussions we have on this forum.

We all (or most of us that have been flying) know that the prudent thing to do will be to make the first flight light. Then and only then will the progress to
different flight parameters including increased front seat loading be done.

While in this process and long before any quoted numbers here of front seat
weights, the "feel" of this loading will be determined i.e. as the weight increases the elevator authority "feel" will be known.

That being said, if there is anybody that would insist on being so stuborn as to make the first flight loaded to the max or built their way just to prove their point should do so at an airport with a cemetary off the end of the runway.

I don't believe Dust is one of these people nor do I believe he has a magic flute that makes everybody with a brain say "But Dust says so"

Dust understands what CG is all about as most of us do. What he doesn't understand or know is what this feels like. 440 is just a number. With 800 hp
it may even be a workable number everything else being equal.

Put the Cosy on top of Saturn V booster platform and you won't even need the canard.