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  #1  
Old 05-17-2006, 03:22 PM
Savitar Savitar is offline
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Default Adapting Velocity retracts to Cozy IV

For a long time, I have followed the discussion of retracts vs. non-retractable
gear. Perhaps this has been discussed before and I missed it, but has anyone considered getting the Velocity retracts and adapting them to the Cozy IV?
The craft are similar and derive from the same basic plane. This gear might make a good substitute for the Infinity retracts and would avoid the (supposed) problem of rotational forces on the main spar. Any thoughts?

Savitar
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  #2  
Old 05-17-2006, 08:57 PM
ShaleDC ShaleDC is offline
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Sorry.

We don't discuss any actual technical information about retracts. This is a forum only for criticizing the decision to use or not use retracts, a la "retracts are stupid, you won't go faster, it'll take to long".

Better luck elsewhere.
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  #3  
Old 05-17-2006, 10:01 PM
Kraig Kraig is offline
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Oh for crying out loud ShaleDC, I am sure we could discuss technical information concerning retracts here.

Not that I have any to give. My take on retracts is that you won't go any faster, it will take to long, and I think they are stupid.

Kraig

(For those with little or no sense of humor, that was sarcasm).
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  #4  
Old 05-17-2006, 10:19 PM
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Cozy Girrrl Cozy Girrrl is offline
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Dear Savitar,
I'm afraid Shale is correct but since I'm a born rebel I'll take the arrows =).
We went with the Infinity retracts because we wanted the available features and they were just "us" ..probably a combination of geeky, techie and whatever features, one way or another we were going to have a full retract plane be it a canard or Lancair or whatever (some people just can't get THAT message through their heads).
On one end of the spectrum you have Infinity's, on the other end you have Velocities gear, kind of in the middle you have Eracer/Berkut gear of varying versions from delicate to robust and halfway between them over next to Velocities I think is where Drybread gear comes. Unfortunately Drybread gear is no longer available, nor is Steve Drybread. So lets say you have treee possibilities which narrow down to two since the Eracer/Berkut gear is not really available either.
I give Velocity gear a thumbs up on several features. Simplicity, simplicity, simplicity. Thats a few so far.
They have a single actuator I believe, much less plumbing, considerably fewer points of failure. They seem to be quite reliable, you do not hear of failures and they put them in all the big velocities. They have the largest installed base of retractable gear in canard aircraft.. thats a guess not a fact.
And thats all I know about them. Oh, a Cozy is not a Velocity so you are on your own with the installation. Thats not a bad thing, just a point. If you are serious you might also talk to Scott Swing and see if he has information on anyone who has done it and maybe you can get more information that way. I seem to remember Jeff Russell leaning that direction with Aerocanard. The original Aerocanard RG was with infinity gear.
Best of luck, tell us what you learn.
Regards, Chrissi
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  #5  
Old 05-18-2006, 11:43 AM
Buly Buly is offline
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Default Retracts

All I know is (first hand) that if John Slade had a full retract, he will be in for a year of repairs and lots of money. You are defeating one of the great benefits of the design: Gear up landing is a non event. Don't say that you know what are you doing and you have a warning system. John had all of the above. They failed and we were sliding on the nose.
Buly
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  #6  
Old 05-18-2006, 12:11 PM
Lynn Erickson Lynn Erickson is offline
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Quote:
Originally Posted by Buly
All I know is (first hand) that if John Slade had a full retract, he will be in for a year of repairs and lots of money. You are defeating one of the great benefits of the design: Gear up landing is a non event. Don't say that you know what are you doing and you have a warning system. John had all of the above. They failed and we were sliding on the nose.
Buly
What happened to the warning system, why did it fail to warn you?
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  #7  
Old 05-18-2006, 12:24 PM
Buly Buly is offline
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Default Retracts

I don't know. Just that warning systems and check lists sometime don't help. All it takes is one glitch and you are up for FAA accident reports, investigation, engine tear down, new prop, airframe repairs, insursnce rate hike (if you can get one).
Retract planes are cool looking and few knots faster, but for my budget, one gear up landing may be the end of it. If you have the bucks, go for it.
Buly
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  #8  
Old 05-18-2006, 12:38 PM
argoldman argoldman is offline
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There are three main reasons for the desire of retractable gear (other than the desire for increased maintainence and possible short rollouts)
1. Increased speed, climb etc.
2. That wonderful feeling of the gear retracting on climbout (actually the sound of the mechanism) or extending before (we hope) landing.
3. Seeing the 3 down and locked right before you land


There is some question as to the actual speed increase with retracts. I do know that in all of my previous retractable planes (6) performance with the gear down was like cutting out a couple of cylinders. In those planes the retraction yielded a great speed increase. Don't know with the cozy. One might get some idea with compairing The velocity RG with its fixed leg cousin.

The cozy is a combination of 1, 2, &3. You get some increased speed, get to hear that great noise (if you have electric) and get to see the light.

Additionally you get the thrill of actually flipping the switch.

Actually, my age, and desire to get my craft done quickly prevented me from considering the retracts.
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  #9  
Old 05-18-2006, 12:54 PM
Marc Zeitlin Marc Zeitlin is offline
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Quote:
Originally Posted by Savitar
.... has anyone considered getting the Velocity retracts and adapting them to the Cozy IV?
Chris Essylstyn has done essentially that with his stretched O-540 COZY MKIV. He'll be at OSH this year with it. That's the only one I know of, but it seems to be working well, although it was one of the reasons that he needed to stretch the plane, IIRC.

Quote:
Originally Posted by Savitar
The craft are similar and derive from the same basic plane. This gear might make a good substitute for the Infinity retracts and would avoid the (supposed) problem of rotational forces on the main spar.
As you state, there's only a "supposed" problem of torquing the spar - in fact, there has never been a spar problem due to the Infinity Gear. The nice thing about the Infinities, over the Velocity Gear, is that they take ZERO room in the fuselage, and the area in the fuselage (folks, note the spelling of the thing that you sit in) that USED to hold landing gear mounting points can be used to replace most of the fuel lost in the strakes from the Infinity Gear mounting.

Quote:
Originally Posted by Savitar
Any thoughts?
I've never understood that question at the end of a post....
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  #10  
Old 05-18-2006, 01:06 PM
Marc Zeitlin Marc Zeitlin is offline
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Quote:
Originally Posted by argoldman
1. Increased speed, climb etc.
Speed, yes - climb differences will be marginal, because you climb at much lower speeds than those at which you cruise. The Velocity web pages claim approximately 100 - 200 fpm climb rate difference at sea level, but the same caveats apply as for speed, as stated below.

Quote:
Originally Posted by argoldman
There is some question as to the actual speed increase with retracts. I do know that in all of my previous retractable planes (6) performance with the gear down was like cutting out a couple of cylinders. In those planes the retraction yielded a great speed increase.
Well, sure, Rich - the gear down was not faired, there were no wheel pants, and there was no drag reduction optimization done to the gear that retracts - that's no different than the Infinity/Velocity retractable gear. It would be magic if a retractable gear aircraft did NOT show a huge performance decrease when extending the gear.

Quote:
Originally Posted by argoldman
Don't know with the cozy. One might get some idea with compairing The velocity RG with its fixed leg cousin.
And the Velocity web page indicates a 15 Kt. difference for all models except the XLRG with the 300/310 HP engine, where they claim 20 Kts. Remember that the Velocity-FG gear legs are not well faired, the wheel pants are relatively high and are NOT pressure recovery pants, and the nose gear is down, too, and is not faired particularly well.

Take ~1/3 of the speed difference off because we retract the nose gear in any case, and another 5-7 kts for good wheel pants and faired gear. You're left with a difference of ~5 kts.
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  #11  
Old 05-18-2006, 01:27 PM
argoldman argoldman is offline
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Quote:
Originally Posted by Marc Zeitlin
Speed, yes - climb differences will be marginal, .
(dirty retracts)
Common Marc, Give me a break,(although you are right)

That'll teach me to respond to these things, between patients, without thoroughly reading them.
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  #12  
Old 05-18-2006, 02:36 PM
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MarbleTurtle MarbleTurtle is offline
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Quote:
And the Velocity web page indicates a 15 Kt. difference for all models except the XLRG with the 300/310 HP engine, where they claim 20 Kts. Remember that the Velocity-FG gear legs are not well faired, the wheel pants are relatively high and are NOT pressure recovery pants, and the nose gear is down, too, and is not faired particularly well.
Take ~1/3 of the speed difference off because we retract the nose gear in any case, and another 5-7 kts for good wheel pants and faired gear. You're left with a difference of ~5 kts.
Well... no. I doubt the short nose wheel unit would contribute 1/3 the drag, but that is a bit of a red herring anyway. The largest single problem I see with the Velocity retract system is the large half-moon openings left where the wheels are not entirely enclosed while retracted. These openings into the recessed wheel wells are located in a high pressure area under the wing.

Very draggy!

So the difference between a suckey non-retract system and a suckey retract system is 15 knots. If we keep strolling down this primrose path of logic, the difference between a good non-retract system and a good retract system is 15 knots. Woo Hoo! That was easy to figure out.

In order to know for certain what the difference will be, someone will need to take a properly faired standard gear set, and then convert it to a proper retract system. This has been done, but apparently the example given on the Infinity Gear site are completely unacceptable because of an antenna placement (or unacceptable pants... I don't remember) in the before conversion configuration that was not there in the post conversion configuration. Oooookay. Well... any new volunteers out there? Waiter?
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  #13  
Old 05-18-2006, 03:01 PM
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Dust Dust is offline
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well - what is the cost diference and what is the internal space required by velocity retracts
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  #14  
Old 05-18-2006, 09:14 PM
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Waiter Waiter is offline
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Quote:
Well... any new volunteers out there? Waiter?
NOPE, Not me. I've made far to many changes that are all in the name of "Drag Reduction". So a BEFORE / AFTER will not be valid.

1) Completely enclosed nose gear doors (none before).
2) Eliminate fuel sump blisters.
3) Cut off lower winglets
4) Change to downdraft cooling (no more NACA scoop on bottom)
5) Internal rudder bellhorns.
6) Even got rid of the boarding step and the external transponder antenna.
and of course,
7) retract main gear.

As a note, my old fixed mains were standard plans built with wheel pants. There was no effort made to clean up the original gear before the retrofit started!

Waiter
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  #15  
Old 05-18-2006, 10:41 PM
Nathan Gifford Nathan Gifford is offline
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I think the faster you go the better retracts look. I haven't seen pressure recovery speed pants on a F-16.

The really big question that remains unresolved is how much faster is a Cozy with retracts. Over the years it still been mostly educated guess work.

Correct me if I am wrong Marc, et al, but drag goes up by the square of the speed. So if you are really planning to go quite fast retracts may well benefit you.

However, some of fastest EZs have fixed gear. I just haven't heard at what speed do retracts make a lot of sense.
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