Who wants good Retracts?
10-29-2004, 10:56 AM
#1
Who wants good Retracts?
There has been a lot of discussion regarding mechanical retracts. About 12 years ago, I was so tired of the crap retracts that were on the market that I designed and built my own. My retracts are hands down THE BEST you will ever use, and they are approximately the same size as all of the others.
Their operation is so effortless that a single STANDARD servo can easily operate two of them.
When I was making them, I sold them for $50 a pair, and I was selling them faster than I could make them. But about the time I was going to start large scale production, I switched careers and no longer had access to the CNC machines.
I am now thinking about approaching some manufacturers about making them available to the general public. So my question is:
How many of you are willing to pay a few bucks more for mechanical retracts that really work? (Let me know either way so I can bring your input to manufacturers. And feel free to ask any questions)
Their operation is so effortless that a single STANDARD servo can easily operate two of them.
When I was making them, I sold them for $50 a pair, and I was selling them faster than I could make them. But about the time I was going to start large scale production, I switched careers and no longer had access to the CNC machines.
I am now thinking about approaching some manufacturers about making them available to the general public. So my question is:
How many of you are willing to pay a few bucks more for mechanical retracts that really work? (Let me know either way so I can bring your input to manufacturers. And feel free to ask any questions)
10-29-2004, 12:43 PM
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RE: Who wants good Retracts?
Anybody that would build a good set of mechanical retracts for a 20 to 25 LBS plane would have me for a customer. Hope it comes about!
Lonnie
Lonnie
10-29-2004, 04:27 PM
#10
RE: Who wants good Retracts?
Ok, here's a pic. As you can see, they are about the size and shape of other brands. They are designed to be operated with nyrod, but can also use steal wire. The servo end of the rod has been sharpened to make it easy to slide into the EZ Connector on the servo (See pic 2). The reason I point this out, is that you will see in the video that I can raise the gear by pushing on the pointed end of the rod (This would drive the rod right through your finger with a standard retract)
The video can be downloaded [link=http://204.96.183.34/RCU/grafx/Retract.wmv]HERE[/link]
The video can be downloaded [link=http://204.96.183.34/RCU/grafx/Retract.wmv]HERE[/link]
10-29-2004, 05:10 PM
#12
RE: Who wants good Retracts?
Possibly, but it would be better to machine or injection mold them. And they require a CNC machine, there's no way you could do it by hand.
There is a rather ingenious (if I do say so myself - and I do
) yet simple over-center spring that makes for the smooth movement.
There is a rather ingenious (if I do say so myself - and I do
) yet simple over-center spring that makes for the smooth movement.
10-29-2004, 05:58 PM
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RE: Who wants good Retracts?
Crappy Great Planes retracts killed my beloved Ultra Sport + ! I would ressurect it if there were something better available! Nice looking work Mike!
10-29-2004, 08:30 PM
#16
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RE: Who wants good Retracts?
Hi Mike:
No - I am not in the market for retracts, but for you I have some food for thought. Like you, only it's been fifteen years, I got fed up with the retracts on the market, and decided to design my own. These were for 1/4 and 1/3 scale planes.
Like you, I started making mine like all the others - and when I was done, they were no better than the others. Then I took a completely different approach. All you want to do is to rotate a gear in some fashion about ninety degrees. One of the big problems with the gears on the market, was that the hold down platform wasn 't large enough to withstand the loads exerted on them by the longer landing gear. Thus, on any landing other than a very smooth one, the gear was likely to rip out, and most of them did.
So I came up with a completely new idea. Why not build the gear into the wing from the very beginning, on an aluminum tube that rotated between the front and rear spars. Wooden bearings securely fastened to the spars held the tube in place. Inside the tube, I machined a wooden block that was press fitted in the spot where the gear was to be located. The gear was held in place be two locking screws. If a gear bent for some reason, just pull it out, and insert a new one. It can be any wire size that you want it to be - no restrictions.
Now all that is left to do is to figure out how to rotate the aluminum tube. This was quite a challenge. First off, all the gears that I had used were pneumatic. I decided mine had to be electric. I went to K-Mart and found some real cheap battery operated screwdrivers, and these became the power source - running off 4.8 volt nicads. I devised an ingenious method of rotating the tube by turning a screw through a moveable block tied to the tube by two fixed posts. The moveable block had to stay in a fixed plane relative to the screw, and it changed planes in relation to the tube as the tube was rotated. The amount of rotation was controlled by two limit switches, that were completely variable. For instance, if your plane had 5 degrees of dihedral, and you therefore wanted your gear to only rotate 85 degrees, all you needed to do is to set the switches that way.
We installed these gears on some racing AT-6's with G-62's, and they worked flawless. The electric provided about a seven second cycle from down to up, and vice versa. We built the gear tube right into the fiberglass wing section, and it was stronger than - you know what.
One of the biggest advantages of this design is the fact that the gear is always locked, in any position, either up, down, or half-way. You needn't worry about a gear collapsing when a side load was applied.
The planes that these gears were in are long gone - Have no idea where they ended up. Also have no photos of the actual installation, but I still have the prototype box that I used to prove that the design would work. Consequently, I dug it out of the "old stuff", and took three photos for you to look at. I didn't have a gear and wheel to install, so I just stuck a piece of brass tube in where the gear would go.
Photo one is the gear in the retract position. Photo two is the gear as it moves from the retract position to the down position. Photo three shows the gear in the down position.
I only show you all this to get you to imagine other ways of doing the job. I agree that the whole industry needs better retracts, but it isn't going to happen if we continue to copy the designs that are already out there. So, put on your thinking cap; start with a clean sheet of paper; and see what you can come up with.
Can you figure out a better way to rotate the tube? That was my biggest hurdle. The rest was easy.
No - I am not in the market for retracts, but for you I have some food for thought. Like you, only it's been fifteen years, I got fed up with the retracts on the market, and decided to design my own. These were for 1/4 and 1/3 scale planes.
Like you, I started making mine like all the others - and when I was done, they were no better than the others. Then I took a completely different approach. All you want to do is to rotate a gear in some fashion about ninety degrees. One of the big problems with the gears on the market, was that the hold down platform wasn 't large enough to withstand the loads exerted on them by the longer landing gear. Thus, on any landing other than a very smooth one, the gear was likely to rip out, and most of them did.
So I came up with a completely new idea. Why not build the gear into the wing from the very beginning, on an aluminum tube that rotated between the front and rear spars. Wooden bearings securely fastened to the spars held the tube in place. Inside the tube, I machined a wooden block that was press fitted in the spot where the gear was to be located. The gear was held in place be two locking screws. If a gear bent for some reason, just pull it out, and insert a new one. It can be any wire size that you want it to be - no restrictions.
Now all that is left to do is to figure out how to rotate the aluminum tube. This was quite a challenge. First off, all the gears that I had used were pneumatic. I decided mine had to be electric. I went to K-Mart and found some real cheap battery operated screwdrivers, and these became the power source - running off 4.8 volt nicads. I devised an ingenious method of rotating the tube by turning a screw through a moveable block tied to the tube by two fixed posts. The moveable block had to stay in a fixed plane relative to the screw, and it changed planes in relation to the tube as the tube was rotated. The amount of rotation was controlled by two limit switches, that were completely variable. For instance, if your plane had 5 degrees of dihedral, and you therefore wanted your gear to only rotate 85 degrees, all you needed to do is to set the switches that way.
We installed these gears on some racing AT-6's with G-62's, and they worked flawless. The electric provided about a seven second cycle from down to up, and vice versa. We built the gear tube right into the fiberglass wing section, and it was stronger than - you know what.
One of the biggest advantages of this design is the fact that the gear is always locked, in any position, either up, down, or half-way. You needn't worry about a gear collapsing when a side load was applied.
The planes that these gears were in are long gone - Have no idea where they ended up. Also have no photos of the actual installation, but I still have the prototype box that I used to prove that the design would work. Consequently, I dug it out of the "old stuff", and took three photos for you to look at. I didn't have a gear and wheel to install, so I just stuck a piece of brass tube in where the gear would go.
Photo one is the gear in the retract position. Photo two is the gear as it moves from the retract position to the down position. Photo three shows the gear in the down position.
I only show you all this to get you to imagine other ways of doing the job. I agree that the whole industry needs better retracts, but it isn't going to happen if we continue to copy the designs that are already out there. So, put on your thinking cap; start with a clean sheet of paper; and see what you can come up with.
Can you figure out a better way to rotate the tube? That was my biggest hurdle. The rest was easy.
10-30-2004, 01:37 AM
#18
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RE: Who wants good Retracts?
I've looked at some Wing Mfg. electrics from a long time ago. Might be something to tinker with too. Weak trunnion block, but the things do work nicely if a little noisy. Modern electric motor would probably help too. Plus, someone could make a PC board to hold the components out of the way as well.
10-30-2004, 07:17 AM
#20
RE: Who wants good Retracts?
Minn,
May I suggest that one reason your mechanicals work so well is that you machined them from billet using a CNC and did the tolerancing properly. All too often I see a good design being redone for production to get a few pennys out and it turns out to be mass produced mediocrity. Just my thoughts after being in Automotive for the last 20 years.
John
May I suggest that one reason your mechanicals work so well is that you machined them from billet using a CNC and did the tolerancing properly. All too often I see a good design being redone for production to get a few pennys out and it turns out to be mass produced mediocrity. Just my thoughts after being in Automotive for the last 20 years.
John
10-30-2004, 11:20 AM
#22
RE: Who wants good Retracts?
Mike,
I was basically talking fabrication ie stamped metal verses milled aluminum. Obviously not having seen your design I can't comment on the design itself. Be that as it may --- Build it, if the quality is there, I'll buy it.
John
I was basically talking fabrication ie stamped metal verses milled aluminum. Obviously not having seen your design I can't comment on the design itself. Be that as it may --- Build it, if the quality is there, I'll buy it.
John
10-30-2004, 04:27 PM
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RE: Who wants good Retracts?
Mike, I'm impressed. WM put mechanical retracts on the 82" WS P-51. They work, but thats about all I can say for them. I use a 105 oz Hitec retract servo, which you would thunk should be plenty of torque, but the gear moves slowly as though I need even more torque.
The big problem I see with the WM mechanical retracts is that the wire struts are so flimsy that they bend as though the retracts are about to collapse if any side load is applied when doing a tail waggle to slow down on a hot approach. A friend of mine purchased the WM Giant Zero with the same retracts. He had to add nearly two lbs. to the nose to get the CG right. When he would taxi the Zero, the wire struts were so flimsy that the Zero would start doing a bouncing act that was quite comical to watch. It looked like one of those cars where the front end jumps up and down. He disliked this so much that he replaced with Robart air retracts. I would be interested if you plan on beefing up the struts a bit for larger airplanes.
The big problem I see with the WM mechanical retracts is that the wire struts are so flimsy that they bend as though the retracts are about to collapse if any side load is applied when doing a tail waggle to slow down on a hot approach. A friend of mine purchased the WM Giant Zero with the same retracts. He had to add nearly two lbs. to the nose to get the CG right. When he would taxi the Zero, the wire struts were so flimsy that the Zero would start doing a bouncing act that was quite comical to watch. It looked like one of those cars where the front end jumps up and down. He disliked this so much that he replaced with Robart air retracts. I would be interested if you plan on beefing up the struts a bit for larger airplanes.
10-30-2004, 05:28 PM
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RE: Who wants good Retracts?
You have my interest. I have been avoiding building planes with retracts because they didn't seem to hold up well after a less than perfect landing. Which, by the way seem to be the majority of mine.
A good affordable sturdy mechanical gear will change that.
DaveB
A good affordable sturdy mechanical gear will change that.
DaveB
