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  #16  
Old 05-19-2006, 01:31 AM
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CBarber CBarber is offline
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The Velocity retracts, from what I have seen in person and via our manual, take up almost no more room than the fixed gear in the fuselage. There is about an 8 to 12 inch gap between the firewall and the gear bulkhead that the fixed gear slide through (the big arch) and get bonded in. The retracts use this same space to retract and extend using a pivoting leg pin. I have had many Velo folks comment on how simple they are. Unless I have missed something (and since I don't have the retracts I have only had a residual interest and comments from the factory folks), I do not think they take up any more room.

You may want to check out the contruction photo's that are available online under the builders page link. It should give you some insight. The price for the retracts has just gone up to $8500.00.

All the best,

Chris
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  #17  
Old 05-19-2006, 02:14 AM
Marc Zeitlin Marc Zeitlin is offline
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Quote:
Originally Posted by Nathan Gifford
I think the faster you go the better retracts look. I haven't seen pressure recovery speed pants on a F-16.
That's true - drag reduction makes a lot more difference at higher speeds. Of course, the COZY doesn't go supersonic, nor do you have essentially unlimited $$ to spend on it.

Quote:
Originally Posted by Nathan Gifford
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.
And mucho not so educated.

Quote:
Originally Posted by Nathan Gifford
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.
They benefit at pretty much any speed above 100 mph or so - the question isn't whether there's less drag - of course there is. The question is whether it worth it to you. We know the cost in $$ and time (and complexity and safety) - what we don't know is the magnitude of the payoff in speed (the subjective payoffs are up to each builder, obviously). At the speeds we fly in the canards, it'll be somewhere between 5 kts (if you believe the theory and the people that have done both, and measured the differences accurately) to 20 kts (if you believe the vendors and wishful thinkers).

For any given builder, there's a point at which it will be worth it to them to spend the $$$ and effort - for some, it may be worth it even with NO speed increase - they just like retracts. For others, it's not worth it even if the payoff IS 20 kts.

It's a personal thing, and there's no right answer. The only thing that I want to make sure of is that people are making their decisions based on accurate information on what the payoff IS.

Quote:
Originally Posted by Nathan Gifford
However, some of fastest EZs have fixed gear. I just haven't heard at what speed do retracts make a lot of sense.
See above. There's no answer to that question.

Folks have brought up F-16's and Voyager as instances of aircraft with retracts. Both single purpose aircraft, not built for general use. One with unlimited budget and speed needs. Another with a safety factor of 1.00001, built to fly at gross weight ONCE, and requiring every ounce of performace to be able to meet it's goal.

Whether a COZY has a range of 950 NM or 980 NM, or has a top speed of 190 kts or 205 kts due to adding retracts, is not something that will determine the viability of the aircraft, unlike the other two aircraft mentioned. Therefore, using them as analogies in inappropriate.

Retracts should be used if an individual finds that the gains (which are real - the issue is the magnitude) are worth the cost. Some will decide they are, and some will not.
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  #18  
Old 05-19-2006, 05:03 AM
ShaleDC ShaleDC is offline
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Didn't we have this retract vs. non retract debate 2 weeks ago (and 3 months before that, and 6 months before that, etc...)???

I think the purpose of the question was to discuss technical details and merits of using Velocity gear, in specific. Not an arguement over the generic pro's / cons of retracts.

Since no one else wants to answer the question, check out this website for some pics & descriptions of the the Velocity retract install. http://www.rguerra.com/velocity/
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  #19  
Old 05-19-2006, 07:06 AM
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karoliina karoliina is offline
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Quote:
Originally Posted by ShaleDC
Since no one else wants to answer the question..
Well, it can be also so that no one else can answer the question despite one might want to.

We are still considering retracts but haven't yet just figured out how to do them. Doing them from scratch is quite a lot of work on a territory that is somewhat unknown to me and then there are for example availability problems in commercial retracts.

However, it can be justified with added efficiency and thus saved cost:

205-190 kt = 15 kt (15 nautical miles per hour more) which makes difference of travelled 30000 more nautical miles in 2000 hours (engine TBO). In other words, if the difference is 15 kt, 30000 nm more at no extra cost once during the TBO of the engine.

The difference is more significant in countries where the gasoline price is high. In USA it is a lesser problem. You don't have AVGAS costing 2.5 EUR per liter (9.5 EUR per gallon = about 11 USD per gallon). Anyway, with that cost 10 gallons costs 110 USD.

30000 nm / 190 kt = 158 hours savings for RG.
~158 hours * 11 USD per gallon * 10 gallons per hour = 17368 USD savings for RG

Ok, higher maintenance costs etc. reduce the difference between RG and FG and also more efficient engine makes the gap smaller.

So if you spend 5000 for RG, 2000 for maintenance, you save:
17368 - 7000 = 10368 USD.
---------------

The saving is enough for buying MT propeller constant speed prop with the saving alone.

This calculation is based on next year's AVGAS price in Finland.

We did similar calculation with buying our new (hybrid) car. It was more costly to buy, but during 100000 km it pays itself back as it consumes about 50% of the gasoline the previous car did with no degradation in performance, size or comfort compared to the previous car, in fact this one is bigger, nicer, cooler etc. than the previous one.
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  #20  
Old 05-19-2006, 09:01 AM
Nathan Gifford Nathan Gifford is offline
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Quote:
Originally Posted by karoliina
Well, it can be also so that no one else can answer the question despite one might want to...However, it can be justified with added efficiency and thus saved cost:

205-190 kt = 15 kt (15 nautical miles per hour more) which makes difference of travelled 30000 more nautical miles in 2000 hours (engine TBO). In other words, if the difference is 15 kt, 30000 nm more at no extra cost once during the TBO of the engine...

30000 nm / 190 kt = 158 hours savings for RG.
~158 hours * 11 USD per gallon * 10 gallons per hour = 17368 USD savings for RG
But what if the speed difference is close to 5 kts?

10000 nm / 190 kts = 53 hours

~53 hours * 11 USD/gal * 10 gal/hour = $5830

Of course if its 10 knots faster then you can double that figure.

I really think at 15 knots it starts to look attractive. Below that considering all that you must do the payoff is marginal.

You also should undertake this mod understanding the risks. These are not unreasonable risks, but they are ones you need to consider. Gear up procedures and practice, strict adherance to procedures, and good maintenance are all essential. Remember one gear up landing probably negates all the economics of retracts if that is your prime reason for retracts (as opposed to all out speed pursuit and cool factor).

After investigating what it actually costs to put in RGs, my prime motives were the extra economy. For me the benefits between economy and reliability did not fit for me. As someone else has said your mileage may vary...
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  #21  
Old 05-19-2006, 02:57 PM
Marc Zeitlin Marc Zeitlin is offline
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Quote:
Originally Posted by ShaleDC
Since no one else wants to answer the question.....
You must have missed post #9 in this thread, in which I answered the OP's question, and pointed him to a specific aircraft that had done what he asked about.
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  #22  
Old 05-19-2006, 03:12 PM
ShaleDC ShaleDC is offline
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I guess I did.
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  #23  
Old 05-19-2006, 03:47 PM
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Default velo/cozy/rg

Quote:
Originally Posted by ShaleDC
I guess I did.
here it is
what is the cost of velo gear? is it less than inf.?
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  #24  
Old 05-20-2006, 11:19 AM
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Who was making the actual gear legs for the Drybread gear?
....Chrissi
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  #25  
Old 05-20-2006, 08:44 PM
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Does anyone have pictures of the mechanicals of the Velo or Drybread gear?
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  #26  
Old 05-21-2006, 12:50 AM
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Maybe someone found some molds in a haystack.
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  #27  
Old 05-21-2006, 10:54 AM
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Quote:
Originally Posted by JonC
Does anyone have pictures of the mechanicals of the Velo or Drybread gear?
Velocity has pictures posted under their (open) builder's section, link below, I won't try to post pics since there's two pages there.

http://www.velocityaircraft.com/phot...Gear/index.htm

There are also some good pictures at Rich's site http://www.rguerra.com/velocity/ check the "Main gear" link.

Brett
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  #28  
Old 05-22-2006, 02:56 PM
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Quote:
Originally Posted by Steve parkins
the first post was not what i read? how strange. 2nd try.......

The retrofit kits as per picture are available and will include the main gear legs, gear doors, gear wells, special over center device, hydraulic pump & cylinder, and special miscellaneous hardware. The kits are made to fit Long EZs or Cozys. Approximate cost is $3,000. Complete installation of kit is also available. For more information or the $25 video please email Steve Drybread or call 1-317-250-4391.
I don't think Steve Drybread's widow would appreciate a bunch of eager newbies bugging her for information on the gear he was developing, please be considerate.
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  #29  
Old 05-22-2006, 04:13 PM
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Ok, since it isnt really touched on with either site...

I gather the main gear on the Velocity (as well as Drybread's) is retracted using the cable that runs from the end tabs on the overhead linkage forward. When the cable is pulled the linkage pulls out of the overcenter clip and pulls the gear legs down to retract the gear. To lower, the cable is released, the gear depends totally on gravity and the spring on the overhead linkage to pull downlock into place.

Correct?

So does it connect to a cylinder somewhere forward or to the nose gear?
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  #30  
Old 08-26-2007, 08:42 PM
Jeff122670 Jeff122670 is offline
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Default Re: Adapting Velocity retracts to Cozy IV

does anyone have ANY video of the Velocity retracts actually retracting. i am looking for how the inner guts of the system work.

thanks!

Jeff
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