ogarrid

I would like to make my own retracts. Does anybody know where can I find some plans , drawind , cad diagram or whatever design for starting this challenge?

thanks

mulligan

I, too, will be making my own oleos/struts for a 1/7 C-47. I am doing so because I will have to- nobody makes them (Robart makes 1/8 DC-3 gear for Ziroli kit) and they are quite unique (so there's nothing close).

I have done a little research and turned up nothing in the area of reference information. I have resigned myself to having to design from scratch, obtain materials and build myself.

I don't know your application, but if you could find struts from Robart or wherever that will work, I'd strongly recommend going in that direction.

If you find anything, I'd love to hear about it.

- George

M Gill

Did you talk to Bob walker at Robart?

I don't know if he'll do a custom job or not, but it is worth asking.

Mace Gill
The Aeroplane Works

soarrich

My Feedback: (98)

You might want to look at http://www.eurokitplane.com I bought a set of stuts from them for up to 20# planes for less than $50, the Robarts where about $100.

My friend makes electric retracts with servos with the pots taken out and replaced with micro switches. The servo truns a bolt and a nut which is attached to a link that lowers the gear.

iFLYrc_Vic

My Feedback: (6)

Can you get more details on how your friend set up the servo retracts?
Thanks,
Vic

iFLYrc_Vic

My Feedback: (6)

Can you get more details on how your friend set up the servo retracts?
Thanks,
Vic

soarrich

My Feedback: (98)

OK I see if I can get him to jump in on this.

soarrich

My Feedback: (98)

Should have read;

OK, I'll see if I can get him to jump in on this.

Next time I'll read it BEFORE I post it.

Lightning Fan

My Feedback: (17)

Not sure if you are sill interested in scratching retracts, but if so, perhaps we can share. I'm scratching a set for a Ziroli P-38, simply because I am cheap. Now I can already hear the old hands telling me this not a place to skimp - thanks for the advice in advance.
The method I'm using is based around a Speed 280 size motor (about $9.00 each). This is driving a long 1/4-20 bolt (leadscrew) that has a traveling nut with an arm to the pivoting strut. The struts I got from Robart. The sheet metal is 16 ga steel - heavy, but then I land poorly (another reason to scratch them - I can fix them). This sounds fairly straightforward, but then you need to consider the motor control. I expect the motor to draw some current, so I am concerned about running motor current through the switches. In addition you need an interface to the receiver - so I have gone with a custom circuit board which incorporates a set of MOSFETs in an H configuration and an off the shelf IC for control. I considered doing this with a single servo and switches - this would also work.
Tools are the primary problem. Cutting and bending the frame of the gear is time consuming but doable. However, there are parts you simply have to tap, and others you must turn (mill). I don't have access to a lathe, so I used my drill press running flat out and a file. It takes a ot of time.
Finally, the ones I made work fine, I've cycled them a ton of times. However .... I'm still building the plane. They have never flown. Therefore - they might not work at all in practice!!

seafurymike

Guys,

Question,

Why have you chosen electric. Are they not prone to "locking up" when the screw is bent??Ofrom heavy landings/grit in screw??

Granted they do have their distinct advantages over pneumatic.

Ogarrid,

Look, if you wish to build your own retracts we need more information from you.

Are they to be scale???. What size???etc...

I have just about finished building my first set of scale (or for that matter, first set of any retracts) and it has taken me 8 months, this is with the availability of milling/lathes at my disposal.

They take quite a while to build. They are a LOT of work and I can understand why it cost so much to purchase these items.

If you wish to build them, the best way to start (i did it this way) was to get a copy of the real retracts that you want to make. Study it and duplicate it as much as possible, if it worked in the plane it will work in your scale one. I did make my retract mechanism from a set of plans that i drew up, these are just a simple cam up/down top and bottom lock. They are pneumatically driven. If you like I can supply any one a set of scanned images (lost the original file and only have printouts left).

Flypaper 2

I have a pair of homade retracts in a 109'' ws FW 190 made from a pair of electric screwdrivers. Built in planetary gearbox driving a screwjack. Micro switches on the ends for stop switches. Actuated with a double pole double throw switch driven by a nyrod to servo at centre of wing. Two double A pencells with charger circuits mounted in the gear leg channel. The 190 has relatively thin wing so wheels are front wheels from a wheelchair. Havn't figured how to email pictures so ask any questions and i'll try to answer.

soarrich

My Feedback: (98)

I asked my friend about them, mechanically they are like Lighting Fan describes with these differences;

He used a 10x32 bolt, he said he wished he had used 1/4x20 to speed them up though.

He has the 10x32 bolt attached to the servo output shaft, with the geared down output of the servo he said it would easily lift 50 pounds.

He uses the circuitry of the servo to drive the servo motor, and micro switches for the end stops.

These homebuilt retracks are in a 30 pound Mustang and work very well, though a little slow.

Lightning Fan

My Feedback: (17)

Regarding the question of why I'm trying electric.
A number of admittedly "soft" reasons.
I have had very little experience with pneumatic design. Near as I can tell, they all depend upon a cam lock mechanism, which the lead screw approach eliminates - the lock is inherent in the design. The pneumatic gear that Robart sells for the P38 looks like it depends upon a rear strut that locks to hold the gear upright. My design has the locking strut going forward - to collapse, the strut would have to be pulled apart - not likely. More importantly, looking at a typical Robart gear, the lock mechanism seemed too hard for me to form with only drills, files and handtools available.
I am also trying to incorporate Fowler Flaps in the model, and they require a substantial drive to actuate - again, I'm going electric here, so this allows me to stay with one "technology" for actuation.
Speaking to reliability .... concur that the lead screw will have to be protected from dirt. However, there is the implication that pneumatics are foolproof. At every giant scale gathering that I attend where I can buttonhole a P38 driver,almost the first thing mentioned is that the P38 bellies in very well. You know, that kind of knowledge comes from experience! I watched a Top Gun video from this year on the DIY network just now and saw two planes belly in with the gear up and failed. So, I really cannot say what approach is better.
Finally - I'm going electric because IT IS CHEAP. The House Commandant is OK with me taking a lot of time making something, but the Beast would kill me if I spent $550 dollars for a set of precision gear that I'll probably bend up in the first landing.

ogarrid

Thaanks averybody for your answers.
There is a lot of usefull information here, but I would like to see some pics if possible.

I will keep loooking for a starting design. I will tell you when thre is something to show.

Thanks again

viper16

I have been thinking about a set of electric retracts for a mustang project,but have never dealt in electrics before. Could someone show me a setup diagram on how to do this,and a materials list of what would be needed? Also how many cycles can one exspect per battery charge. Thanks

MAJSteve

My Feedback: (-1)

I was interested in electric retracts too, so I did one thing that no one here has mentioned - I bought a set of Wing Mfg electric gears. These have some serious years on them and one serious problem - the trunion. Tightening down the setscrew broke it. However, the circuits, motor, jackscrew, and framework would probably work ok if a more durable trunion was made (one of my goals eventually.

Worth a look if you can find a working one for sale.

cmarsden

My Feedback: (11)

send an email to [email protected] and I will send you a zipped file with a dwg foramt that has all deminsions and you can make your own

Baldeagle

My Feedback: (7)

lightingfan
One suggestion on the electeic retracts I would use a seperate battery just fore the retracts. Likes Line has made electric for a long time. That was one of their problems when you hit the retracts it would draw to much voltage away from the reciever. not a good thing to happen. Hope this helps

Utahab8r

I would love to see your plans I too am going to build my own retracts for Hawker Tempost 100" Thanks ahead! [email protected]