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Old Apr 09, 2005, 06:10 PM
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World's smallest air actuated retracts

I have just finished designing and assembling (as far as I know of) the smallest retract actuated by air. It is spring loaded. so if you lose air, they automaticaly come down and lock. It takes about 40 lbs of air preassure to work properly. This is the stearable nose version. the mains use the same parts except the the center piece that does all the work, is smaller, because it doesn't have the stearable strut. This is the first prototype for possible production. Not sure what kind of interest there will be for it. But they won't be cheap. The first pic shows the SpringAir 603, there smallest retract. the second is from Electric Jet Factory. The next is the mechanical micro retracts from Wattage. The length of mine is about 2 1/8", exactly
1 1/8" wide, and .1/2" deep. They should be able to handle up to a 5 lb. airplane.

Larry Epifanio
SouthEast Model Products
Orlando, Fl.
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Old Apr 09, 2005, 06:50 PM
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Lake City, Fl
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As far as interest. Depends on what you mean by "they won't be cheap" What is your target price?

Mike
Lake City, Fl
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Old Apr 09, 2005, 11:41 PM
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Chilliwack, BC
Joined Jan 2004
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Where do you get the compressed air from?
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Old Apr 10, 2005, 01:24 AM
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I for one will think you'll have a tremendous amount of interest, now that higher power minifan are becoming more commonplace. I'd like to see them be a bit stronger for say up to a 7 lb airplane, but 5 lbs is adequate for a single minifan set-up.

Once these retracts are on the market, and builders can be assured of having a reliable supply of them, I think you will see a lot of high end Build and ARF Kits being produced, to take advantage of the new retracts.

There will always be people that balk at the price, at least at first. Hopefully if they are mass produced, the price can come down so they are "competitive" with mechanical retracts + Servo's. How much will the new air retract system weigh?
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Old Apr 10, 2005, 01:39 AM
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hum.... who's going to beta test them first???

Gene
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Old Apr 10, 2005, 03:25 AM
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Nicely done Larry,

You certainly have my attention, 5 lbs. is right around the capacity for a mini480 fan ARF and kit.

Looking forward to seeing them available for purchase.

Best wishes...

Markos
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Old Apr 10, 2005, 10:39 AM
EDF rules... :)
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Joined Nov 1999
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Markos,

Send him a purchase order, when you have them available I will buy a set.

Eric B.
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Old Apr 10, 2005, 04:23 PM
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Micro Retracts, air actuated

I get asked , whats expensive? I looked at having all the parts machined at a local CNC machine shop set up for production. To have a set of 25 made, thats 3 per set, or 75, total, (All the parts are common, except for 1 piece, it denotes a nose gear from a main gear). And I included the support components, like valve, airline, struts, and couplings. I would have to sell the complete set for $300. On the other hand if I made them in my shop ( I wold have to mke jigs & fixtures) I could probably come in around $200 for the 3 retracts. Some of you may think that's high, but there a lot of machine work that goes into these. Everything, including the air cyclinders have to be made.

As for weight, the complete package with everything looks like 2 1/2 oz. The retracts by themselves weight about 1/2 oz. I am also working on a set of breaks, air operated. Will have more on them later
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Old Apr 10, 2005, 04:44 PM
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I have to agree that's not unreasonable for the high ender builders.

As with every other product if there's enough interest and volume the price may start coming down as well. Just a guess.
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Old Apr 10, 2005, 04:51 PM
Xenobiotic Liaison
Tempe, AZ
Joined Jan 2005
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Quote:
Originally Posted by LJE4357
I get asked , whats expensive? I looked at having all the parts machined at a local CNC machine shop set up for production. To have a set of 25 made, thats 3 per set, or 75, total, (All the parts are common, except for 1 piece, it denotes a nose gear from a main gear). And I included the support components, like valve, airline, struts, and couplings. I would have to sell the complete set for $300. On the other hand if I made them in my shop ( I wold have to mke jigs & fixtures) I could probably come in around $200 for the 3 retracts. Some of you may think that's high, but there a lot of machine work that goes into these. Everything, including the air cyclinders have to be made.
I am completely ignorant of air retracts. What advantages do they present? Why would one use them over a mechanical/servo setup?

Does the plane require a compressed air tank? Is the air "provided" by the motor? (etc, etc?)
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Old Apr 10, 2005, 07:06 PM
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Pittsburgh, PA
Joined Apr 2004
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Larry look under Clippard cylinders. You might be able to refit those to what you wish to do. Unfortunately aluminium is a bit difficult to make cylinders out of in small scale (especially sealing them). Hoperfully you can find something useful from them. Might be able to chop off some of your machining cost as they do there cylinders in huge volumes by comparison (popular in robots).

Cyb
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Old Apr 10, 2005, 07:30 PM
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Quote:
Originally Posted by geoffbeneze
I am completely ignorant of air retracts. What advantages do they present? Why would one use them over a mechanical/servo setup?

Does the plane require a compressed air tank? Is the air "provided" by the motor? (etc, etc?)
The advantage of air retracts is ease of installation - just run some airlines, no critical alignment needed. Also there is no danger of the servo's stalling if the strut gets bent back too far on takeoff. Stalled mechanical retract servo's can crash your plane if the power is supplied from the Rx pack. Yes, you need a small tank to supply the air. Generally the tank is filled from a hand pump before flight.
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Old Apr 10, 2005, 08:54 PM
Xenobiotic Liaison
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Quote:
Originally Posted by Chris True
The advantage of air retracts is ease of installation - just run some airlines, no critical alignment needed. Also there is no danger of the servo's stalling if the strut gets bent back too far on takeoff. Stalled mechanical retract servo's can crash your plane if the power is supplied from the Rx pack. Yes, you need a small tank to supply the air. Generally the tank is filled from a hand pump before flight.
Ok, that makes sense. Plumbing is easier than control rods!

What kind of pressure container is used?
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Old Apr 10, 2005, 09:07 PM
go fly! no crashes!
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Honolulu, HI
Joined Jun 2003
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along with partspile, i agree. thats not completely too high for a high end scale build. i'd be interested in a set i think.
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Last edited by Synwpn; Apr 11, 2005 at 02:42 AM.
Old Apr 10, 2005, 09:23 PM
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AIr preassure

I've tested form 40 lbs to 100lbs, With the return spring I am now using, 80lbs is the minimum. As for trying to find cylinders already made, I have not found any that are small enough. The ID of the cylinders are .240.
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