main gear and safety

[schaumr]

Hi all,

Let me begin by saying that my question is merely out of my concern for safety, and is not meant to upset anyone. I admit that if I had more experience flying or building, the answer might be obvious, but since I'm not there yet (and you seem like a pretty open minded bunch) I've decided to ask it anyway:

 

I was at the Infinity web site looking over retractable landing gear for canards, and they seem pretty adamant that re-tracts are safer, because if you have to do a forced landing, you'd at least keep the gear up. The site continued to say that the main gear on fixed-gear canards can come off and rip out a hole under your passenger(s), or you could flip over after the nose digs in during the 'slide'.

 

Now, simplicity is job 1 in my book, so deviation from the plans is really not what I have in mind when I eventually build the Cozy. I would really rather keep the fixed main gear. I know Nat does not endorse the re-tract modification, and his reasons make sense. However, some of the statements made at the Infinity site seem to also make sense (despite their somewhat defensive tone). Can anyone comment on this?

 

Thanks!

Rob Schaum

 

http://www.infinityaerospace.com/infgear.htm

[ekisbey]

You know, I was looking into the same thing last night and logged in here to ask the same question. I noticed the defensive tone also-- they (infinity) do sound rather defensive, which I find somewhat curious. After recieving the official go-ahead last month from the household six, I turned up my research efforts. We've started budgeting and laying out the wish lists. One of the items that came up were the retracts; whether or not we wanted them.

 

I've been especially interested in the retract/fixed debate. Although the performance increase isn't very dramatic considering the performance envelope, and you won't have many (if any) opportunities to see your aircraft with the gear up, I can't deny that the Cozy with retracting gear simply looks cooler, and any performance gain is just that-- more performance from an already impressive plane. Did I mention it looks cooler?

 

In case you haven't seen it yet, Mr. Phillip Johnson has perhaps the most telling arguments in favor of the retracts. Look him up at

 

http://www.geocities.com/plmjohnson

 

I'm not worried about the increased maintenance. Heck, I'm already going to build the thing from scratch, what's a little extra maintenance? My biggest concern is any loss of structural strength to the spars or the skin on the wings. What kind of effect would be caused by the additional turbulence around the deployed gear/wells?

 

Arguments about damage to the aircraft during gear-up/gear-down landings off-field are irrelevant in my way of thinking. If I'm making an emergency landing or ditching the plane, the plane's toast. As long as I wake up the next morning, to heck with the plane. The question in this case is: Does the Cozy fuselage have the integrity to survive a belly landing?

 

Considering that every completed Mark IV I know of and every owner I've spoken to is using the fixed gear option, the plane was designed that way, the designer is almost pleading with you not to use retracts, the retractable gear manufacturer is on the defensive, and the engineering questions that I've encountered, not to mention my wife's opinion on the complexity issue, I'll likely go with the fixed gear. I hope to speak with Mr. Puffer himself when I order the plans (this week if all goes well), and that will settle the issue.

 

Then again, the retracts do look lots cooler. Check out the file if you don't believe me. Courtesy Miscrosoft Paint.exe

 

P.S. Please note that I altered a photo of a Cozy to make it appear to have no gear. I realize there might be legal ramifications to this. If someone objects, I will not hesitate to remove the photo.

[John Slade]

I had similar feelings to you guys. Retracts looks cool, feel "right" and go a little faster. Then, on the other hand they cost a lot more, add complexity put some extra weight in the wrong place. I guess, for me, the balance was tipped by costs, added build time and the lack of flying retract examples. Infinity's (JD Newman) arguments make sense. If you havent had a phone conversation with JD, call him and be prepared for an experience. He's a very interesting guy with a lot to say, and a deep understanding of the canard design and it's history. Whether you go with retracts or not, its worth hearing both sides of the story.

My 2c.

[david010]

One item not mentioned in the discussion about a retract system is insurance. Check it out before making a deposit.

 

dd

[Jim Sower]

I've been mind f**king the whole retract gear concept for years and years. The core issues, IMO, are cost, complexity, safety, performance and cosmetics.

 

All agree that cosmetics are a no brainer. Retracts are soooo cool!

 

The performance issue is a little stickier. FG enthusiasts insist that you gain well under 10 kts cruise (Nat can get pretty shrill on this particular subject), but there is little or no substance to what they say since there are no retract Cozys. The Velocity retracts seem to get upwards of 10 but probably not more than 20 kts better cruise than the FG models. One could argue that they constitute the best comparison as far as performance goes ~ nearly identical airplanes, one FG, one retract. Nobody has a fair sample of retract Cozys, but there are some in the mill.

 

Cost of a retract package is high, but not prohibitive. If you have an automotive conversion (Mazda for example) the money you save on the engine will buy you a nice retract package. The other factor in cost considerations is maintenance and it is kind of a wild card. You never really know how much maintenence it's going to involve. Most of the people you talk to about it (for Cozys) are either trying to sell you a retract or trying to talk you out of it. You can never be sure of their true agenda. There's no owners to give you the straight skinny.

 

Complexity is also a mixed bag IMO. I don't see how it would be a whole lot more difficult to install than, say, a turbocharged Mazda. The main thing about infinity that spooks me is hanging the gear on the end of the spar carry through. ERacer and Velocity both mount their retracts on fuselage bulkheads, and for very good reason. I haven't yet been satisfied that the outboard end of the spar box is a good place. There is landing impact of course, but the gear being mounted on the forward face of the spar box will give it, along with the bending moment associated with positive G's, a significant "nose up" twisting moment. This, I would guess, might be fairly simple to fix and would require maybe a ply or so of spiral wound uni. OTOH, braking would involve a much larger moment arm, and all the force that the brakes apply to stop the airplane, with a moment arm the length of the gear leg would gendeate a largish "nose down" twist on the spar box. Strakes are only floxed to the spar box, and I would think that they would be in some jeopardy since the joint between strake and spar box would be in tension. But then again, the part in tension is the gear well. Velocity/Eracer type retract system on a Cozy would involve rerouting the aileron and rudder controls out of the retract mechanism area. No rest for the wicked. Retract gear is very much up in the air with me. I'm looking at how SQ2000's do with Infinity retracts.

 

Safety is, IMO, a wash. Airplanes ditching gear up are much less likely to "dig in" and "summersault". OTOH, if you ditch with the nose gear down, it should (key word here) be flexing / bending while the main gear gets wiped out (at which time it will follow suit). The gear breaking off the airplane absorbs a LOT of energy that has to be absorbed somewhere else on a retract. I think it's a wash. Just remember to never ditch a FG with the nose wheel up.

 

Lots of theory for your money .... ) Jim S.

[Wayne Hicks]

I wanted to go to retracts too until I saw my hangar mate land gear-up in his Lancair. $25,000 later, his plane is flying again. I also watched a Mooney land gear-up at Sun N Fun 2002.

 

Three thoughts weighed heavily in my decision:

 

First -- Fellas, I don't know about you but I won't have any extra money by the time my airplane is ready to fly. I doubt that I can afford hull insurance. If I were to land gear-up, the Cozy and its engine would be unflyable for a few years while I try to raise the money to fix it. Not to mention the additional year(s) it would take to rebuild.

 

Second -- You KNOW what they say about retract pilots..."There are those that have and those that will." I'm not infallible and I am personally more afraid of forgetting to put the gear down than crashing on landing.

 

Third -- Consider for a moment that most landing accidents occur very near the runway environment. (Hard landings, inadvertent runway departures, running past the runway, etc.) Your gear is most likely down and locked anyway!!! Your gear will surely be damaged, will most likely fold, and you'll get the dreaded prop strike. So what do retracts buy you in these instances?

 

Although I'd surely love retracts, their speed and sexiness, I cannot afford them if I screw up. Bottom line for me. Your mileage may vary.

 

Wayne Hicks

[unick3]

On these planes retracts makes no sense at all. You gain very little on top end, and carry less fuel.

 

I have two blown engines, (emergency landing on a dirt strips) with No problems with detachment, and two gear up landings (one due to my stupidity, and one with carb ice and the LAST thing on my mind was lowering the gear. I just lowered the gear, and off I flew.

 

Try that with a retract system.

 

Simple, cheap, light, easy to install. I am building another canard and there is no way in the world I would install a retract.

[Jim Sower]

<... You KNOW what they say about retract pilots..."There are those that have and those that will." ...>

I've heard that. I do NOT believe that it's carved in stone. I am lucky that just about the first plane I ever flew was a T-34 and I had NOTHING but retract experience and controlled runways the first 4000 hrs I flew. That's a blessing, and I know it. Anyway, we ALWAYS reported abeam with "... XXX - 180 - gear down ..." or, in other circumstances, "... XXX - 180 - gear down - hook down - fuel state ...". I report "... turning base - gear down ..." in my EZ and check it just as religiously as I did then.

 

From the beginning, when I drive around in my car, I think up what if's and devise bullet proof habit patterns. When I am in ordinary daily operations, I practice them again and again the EXACT same way and drive the habit deep into my subconscious. Then, when things get dicey and I'm distracted, and revert to subconscious habit, I'm OK. If I don't have sound, well drilled habits, and I have to do it consciously, and find myself in distracting situations, I'm very apt to screw up and forget something. I keep my rote habits simple and few and SOLID. That way, my head can focus on the weather or traffic or what not and my hand will get the gear down without help from my head.

 

I don't forget my gear because I don't have to remember it. When I'm downwind, it just happens because I don't know how NOT to put it down.

 

Some discipline, lots of thought, many repetitions .... Jim S.

[John Slade]

>because I don't know how NOT to put it down...

Reminds me of RAF jet training. There were lots of times I SAID "finals, three greens", THEN looked to see the gear was up. Often you'd hear these words followed by "Oh Sh...." as the transmit button was held in a second too long. Once I was holding for take-off while a solo student completed his approach. I heard the three greens call, but couldnt see the wheels. As he got closer I saw that the wheels were definately up and yelled "Wheels, Wheels". He powered up, but continued to decend as the engine wound up. His transponder antenna contacted the runway, but then he was able to climb away to fly another day. I wonder if he counts himself as one of the "have" or one of the "will".

Personally, I want a voice annunciator shouting at me. Seems like pretty good insurance for $160 and a few wires.

John Slade

[Jim Sower]

<... "finals, three greens", THEN looked to see the gear was up ...>

That counts. You TALKED, and you LOOKED as you talked. Sound reflex. Good habit. I've done that too. Times when we hit the 5-G break at 400 kts ++ and couldn't slow down to gear speed (220) by the time we were abeam, I trained myself to hang onto the gear handle so I couldn't transmit to call the 180 until I slowed enough to put it down. Same thing.

 

<... solo student ... heard the three greens call ... couldnt see the wheels ...>

He hadn't drilled enough yet. In the Training Comnmand, we used to have [R]unway [D]uty [O]fficer who acted as LSO for solo studs and grade their landings, or a snuff with a flare gun to check studs' gear.

 

We used to say that students were bullet proof ~ they were so far behind the airplane that if it ever DID crash, they wouldn't get hurt.

 

Best .... Jim S.

[Wayne Hicks]

I've NEVER forgotten to put the gear down during normal, downwind approaches. But I've screwed up SIX TIMES! (At least!) I was on long finals on instrument approaches, arguing with arrogant controllers, losing gyros left and right, flying partial panel, ceilings down to minimums.....and then it happened. Realized I landed GEAR UP, all because I was pre-occupied, mentally overloaded.

 

THANK GOD THIS WAS ON A SIMULATOR and the "gear-up" didn't cost me a thing! Except for the realization that IT CAN HAPPEN, no matter how thorough the training.

 

Wayne Hicks

[John Slade]

If the designer of the type can do it, so can we builders

 

Jack Wilhelmson's retract unit has an "auto" option that puts the gear down below a certain speed, and raises it above a certain speed. I considered getting this, but then decided that it would teach me to forget about the gear and would be just fine... till it failed.

 

Over on the aeroelectric list we've been discussing cheap ($14) switches for vacuum failure and detecting airspeed that can be plumbed right into the vacuum or pitot system.

 

See http://info.digikey.com/T023/V5/0988.pdf

 

Quoting Bob Nuckolls:

>PSI * 27.68 = in-H20

>Using the forumla P (inches of water) = V (Kts) squared/1467 for

>40kts & 70kts, P would be 1.09. & 3.34 inches of water. The nearest >to that would be: PSF102 384-1017-ND with a H2O range of 2 to 17

 

Hook one of these babies up to a flashing LED ($2) and you have a pretty reliable warning device. Add a voice annunciator ($160) and you can have you're favorite "Bitchin Betty" remind you about gear up and gear down among other things. I'm planning on all the above, even for my retract nosegear. The recording will by my wife saying "John! Gear!" then shouting "GEAR... JOHN GEAR!"

[Jim Sower]

Wayne,

<... NEVER forgotten ... during normal, downwind approaches ...>

<... realization that IT CAN HAPPEN, no matter how thorough the training ...>

I agree, it CAN happen. On straight in approaches, my distance report includes a gear report ... "five miles, no gear... three miles, no gear ... two miles, gear down". I believe that your problems on straight ins suggests less than thorough training at least as regards gear discipline. I had learned to lump turn-to-base and distance-on-straight-in and all similar reports into a sort of "imminent landing" transmission that ALWAYS includes "gear - ???". Hearing myself report to the world that my gear is UP seems to help. This is the part that takes place driving around in the car thinking.

 

Again, it CAN happen, but there's thorough and then there's THOROUGH. And when all else (even really REALLY THOROUGH) fails, there's alarms...

 

John,

The EZ (and I had thought Cozy) had what I thought was a nifty alarm system that connected landing brake, canopy, gear and throttle. High power with either the canopy latch not home, or the landing brake down would sound the alarm. Low power with the gear up would sound the alarm. The alarm included a very audible horn and a prominent red light on the panel. The light (from RS) could be pressed to override the alarm (which could get you into trouble). It worked pretty good for me for the couple of hundred hours I got on my EZ so far. I would look long and hard at what's already in place before I took to reinventing the wheel.

 

Just a theory .... Jim S.

[John Slade]

Well yes, Jim, the Cozy IV plan does call for the "something's wrong" alarm and I'm sure it works well. I'd rather have specific warning which tells me about offending condition.

 

Anyway, this is the experimental catagory. I'm experimenting.

[Jim Sower]

OK. For my own part, I like simple, inexpensive stuff. If I add power for takeoff (or even to take the runway) and the horn and light go on, I look around. Before too very long, I've checked the landing brake and the canopy and fixed the problem. Power off and horn on, I eventually figure out that it's the nose gear.

 

Monitor girl telling me "... Hey big boy, you might want to put the gear down before you get a lot closer to the runway ..." sounds like fun, and I might play with that stuff if I was Al Wick, but I'd have to learn a whole new skill set to get involved with AI.

But more power to ya .... call when it's cheap, simple and off the shelf ... Jim

[John Slade]

Voice annunciation isnt AI, Jim. You just connect the existing micro switches to a $160 box instead of the light / horn.

[ekisbey]

Just be sure the wires aren't backwards.

 

"!REAG NHOJ ...REAG ...!reaG !nhoJ"

[Jim Sower]

Only $180! Just connect a couple of wires! I didn't know it was that simple. Of course there's a body of thought that I'm that simple too Let's see. Connect all the the wires to the box. Frontwards. Program the voice commands. Check it out carefully. Don't want to crash trying to correct a canopy latch problem when it's actually the gear not up or down or something The whole thing just strikes me as a gadget for people who have more money than they know how to spend wisely.

Guess I'll never catch up with technology or fashon .... Jim S.

[John Slade]

>a gadget for people who have more money than they know how to spend wisely.

I respectfully disagree. I don't have a big budget, but a voice annunciator is getting some priority because it's a relatively inexpensive way of alerting me to problems and omissions.

 

>Guess I'll never catch up with technology or fashon .... Jim S.

I didnt know you were trying. I believe that voice annunciation is commonplace in the military and commercial world. They use it cause it works.

[Jim Sower]

OK. Yours will have been in place for a spell before I get to that stage. I'll let you be my beta site, and when I'm ready the technology (and probably the price)should be a good bit better. Particularly in light of all the house payment and tax and etc. money I'll be saving when I move back to God's country

See -- I can be turned ... it just takes a little time and perseverance Jim S.

[John Whalen]

For Jim Sower and others:

 

Have you investigated any other retractable gear other then the infinity? I was wondering if a person could use a Piper or Cessena Gear of off a retired plane and modify the gear length as required for the Cozy?

Just a thought on the retracts issue as I am also looking at them for a off field landing safety factor and for the improved speed.

 

John

[cncdoc]

You know, I had the same thought John. I liked the Infinity Aerospace gear because the designer is familiar with this particular canard/composite design and modifications to the spar and strake area to install it. It is a proven oleo strut design with an emergency system and hydraulic power. It also looks good on the pictures I have seen.

I balked a little at the price (which is up to almost 55K now I think) but then I tried to piece together a system from another airplane:

Cessna: Uses a fuselage mounted system, wont work with Cozy fuselage without extreme modifications.

Piper, Beech, Grumman, Rockwell etc..

Most lower wing design retractable are too short for the Cozy which needs to be about 41.5 inches from the center of the strake to the ground. You can play with the location of the mount but you're still talking about some tall gear.

Some light twin gear would work, except it is very heavy and requires bigger hydraulics and mounting hardware and would take up ALL the room in the strake.

Now, there may be a model of a amphibious or other aircraft with suitable gear that may be close to working (research disclaimer) but when you look at the cost of even a used system (which, if is in good shape, is FAA certified which means top $$ ) it is close to what Infinity wants for the whole 9 yards.

If you are like me, you are still interested in making your own, right?

Well, you have a couple of choices:

Buy the expensive certified used gear and modify it by adding length to the strut,which means changing it's design load characteristics by adding a tube by weldment or clamping/bolting system after you engineer the mounting systems by reverse engineering the gear swing axis, axle axis, wheel to wheel concentricity using unknown location points on an already crowded airframe which is aft cg sensitive. Or, start all over, grab your McMaster Carr catalogue and start pricing 12/24 VDC hydraulic pump systems, air/oil shocks, and hydraulic arms and mounting hardware or maybe a spring assisted oil/air shock for a trailing link design. Then, dont forget the lock down mechanism and emergency lowering system along with the position indication switches and indicator lights for the cockpit controls. You have to plan for the correct take-off posture as well, too high and the nose will be too low and hard to take off, too low and you could have take off problems and prop strike or aft cg exacerbation as well. Then there's the brake lines, brake and wheel alignment, gear doors and strake/spar/fuel cell modification to engineer and plan.

Of course you will have to reconsider the electric nosewheel (why have 2 switches/systems to lower the gear) that will take some engineering as well.

My thoughts are this:

Planning RG for the sake of it itself is not worth it. If it is better and safer than FG maybe it is worth it. If you're just now in the planning stages, it would be a good time to consider it carefully. As far as costs go, well, you're building a 200 mph airplane! Don't go cheap now! The plans gear works and it's as cheap as your going to get. RG is expensive.

As far as the pilot error goes:

I have flown mostly RG planes (since 1975) and I was not military trained. I was drilled with the G.U.M.P. system (gas, undercarriage, mixture, prop(s)) I suppose you can forget anything, even forgetting to fill the tanks with fuel. But getting into any aircraft and flying it off the ground requires training and responsibility. You can learn to fly an airplane in 10 hours. The rest of the 35 hours is teaching you navagation, weather and what to do if something goes wrong.

Of all the aircraft that fly the skies on a regular basis, the majority are RG aircraft. I believe the major cause of pilot error crashes are still fuel mismanagement.

Anyway, I would seriously reconsider flying as a passenger in an aircraft with the pilot in command who said "I might forget to put my gear down"

 

Considering RG is like contemplating asking the prom queen out, either you're all fired up about it and ready for anything she is going to say or you're nervous and sweating and walking away from the whole thing because she "probably wasn't worth it anyway". Besides, there's always the girl next door with "the beat up sneakers and a pony tail..........."

 

 

Always thinking....

 

I have to stay up late at night thinking so I can catch up to Marc (when I'm 137 years old!)

Kevin

[LargePrime]

Few data points.

 

$5500 for JD's system.

-$1500 worth of stuff you dont have to buy.

=$3000 net cost

 

add 20 mph. works out to $150/MPH. If anything else can beat that please let us know.

 

Insurance is a wash as we already have "complex" aircraft.

 

If you have any questions about possable twist on the spar, give JD a call. They did a lot of testing to see if this was safe.

 

I really liked not being able to melt the gear legs with heat from the breaks.

[cncdoc]

I guess since I already have the ol' horse shoe, I have to add the price in (unless I sell it). 600? 700?

I still have to buy the wheels (500 x 5 same), tires, brakes,brake hardware $1100? 1200?

 

THEN I can send $5443.00 plus shipping, handling, any applicable taxes and of course a nice tip for JD!

 

So, let's see here..

 

Optimally, I sell my slingshot for $800 (it's already to install) The 5443 for the RG kit and another 1389.52 for the tires wheels brakes etc is close to 6900 bucks.

Take off my 800 and I get 6100. If I don't buy the parking brake, it's a little less than 6K plus SH tip etc.

But since it's my first date with the "Prom Queen" I'll probably spring for all the marbles.

So in view of the math, am I buying something that I shouldn't have to bring the price down to 3K.

Or is my calculator bogus?

 

Kevin

 

OR...I could be wrong....?

[No4]

I agree entirely with cncdoc,

imho piper or cessna gear wouldn't work / not worth it, but certainly possible.

 

As for gear up's, well that's airmanship. Nearly all commercial aircraft are retractable gear, and failing to lower gear is not a common cause of accidents.

 

Older Pipers and Cessna twins occasionaly experience partial gear failures, and the reccommended action is to land gear up to prevent the uncontrolable condition of one wing's leg up and the other down and locked.

 

The Arrow has a horn which sounds if 20' flap is selected, or if the throttle is closed without gear down and locked. Below 100 knots the gear automaticaly deploys.

 

So I would have to be attempting to land with power on and only 10' flap at above 100 knots and have forgotten my downwind, base, finals, and short finals checks for three greens. Unlikely.

 

The last thing heard on the flight recorder of a South American 737 was "whoop whoop PULL UP TERRAIN!" in a recorded Seattle accent, followed by "SHUDDUP GRINGO!" from the Captain, followed by a loud bang and then silence.

 

Largeprime,

The only thing I can think of is a turbo and a gas mask, any good?