Robart 550-530/Electron/Xicoy/Pro-Drive electric retracts? - RC Groups
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Jun 28, 2017, 12:54 AM
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Eddie P's Avatar
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Robart 550-530/Electron/Xicoy/Pro-Drive electric retracts?


I've got a Tam A-4 I'm replacing the OEM retracts in. They are air, I've replaced the o rings but they still are struggling these days to work well on cold days and generally are getting a bit tired. I've finally gotten around to the idea of replacing them with electric retracts for better reliability.

The model is 19 pounds empty, 23 pounds with fuel. The OEM retracts are almost identical to the Robart 550 or 530 series reverse gear. It's a smaller airframe with tight space. Trouble is, Robart quotes these identically sized 530's and 550's as suitable for models up to 18 pounds. The Robart retracts suitable for 24 pounds are huge and will not fit (I own a set of the larger gear and I've looked to see if they will fit, not even close).

I looked into "Down and Locked" as an optional retrofit for electric and they are quoting $800. I don't think that's gonna happen, it's just too much dough. So looking for possible alternatives.

Any of you guys have any experience with these retract units in jets? Are they stronger than their specs?
Last edited by Eddie P; Jun 29, 2017 at 11:07 AM.
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Jun 28, 2017, 06:49 AM
Registered User
You might want to check out the Prolink series retracts from Dreamworks Model Products.

The Sidewinder series frames are for up to 20lbs

http://www.dreamworksrc.com/catalog/...etract-Set-Pro

The Gemini series for up to 35 lb.

http://www.dreamworksrc.com/catalog/...etract-Set-Pro
Jun 28, 2017, 07:15 AM
Registered User
My T-33 has 550's, with the set of 8,000's I use most often it is somewhere between 20 &21 pounds. I think you'll be fine unless you operate from a cow patch grass field.

I'm also using the 7/16" struts which have been fine, the orig. 3/8" struts were not - they were bent after a few flights.

Question - were the originals aluminum frames? Robarts are steel which would be stronger if the frame thickness is similar...

Quote:
Originally Posted by Eddie P
I've got a Tam A-4 I'm replacing the OEM retracts in. They are air, I've replaced the o rings but they still are struggling these days to work well on cold days and generally are getting a bit tired. I've finally gotten around to the idea of replacing them with electric retracts for better reliability.

The model is 19 pounds empty, 23 pounds with fuel. The OEM retracts are almost identical to the Robart 550 or 530 series reverse gear. It's a smaller airframe with tight space. Trouble is, Robart quotes these identically sized 530's and 550's as suitable for models up to 18 pounds. The Robart retracts suitable for 24 pounds are huge and will not fit (I own a set of the larger gear and I've looked to see if they will fit, not even close).

I looked into "Down and Locked" as an optional retrofit for electric and they are quoting $800. I don't think that's gonna happen, it's just too much dough. So looking for possible alternatives.

Any of you guys have any experience with these retract units in jets? Are they stronger than their specs?
Jun 28, 2017, 10:27 AM
EDF all the way!
bruff's Avatar
Also check out Electron-retracts.com.
I'm using them in my 21 lb Cougar with no problems.
Bob
Jun 28, 2017, 12:18 PM
Official Boat Bum
Eddie P's Avatar
Quote:
Originally Posted by RGBvr
You might want to check out the Prolink series retracts from Dreamworks Model Products.

The Sidewinder series frames are for up to 20lbs

http://www.dreamworksrc.com/catalog/...etract-Set-Pro

The Gemini series for up to 35 lb.

http://www.dreamworksrc.com/catalog/...etract-Set-Pro
RGBvr, thank you for those links!

Quote:
Originally Posted by bruff
Also check out Electron-retracts.com.
I'm using them in my 21 lb Cougar with no problems.
Bob
Thank you Bob! I see the configuration is standard, meaning the retract pulls the strut into itself and the strut and trunion retract and lay over the motor actuator. The Tamjets gear are "reverse" meaning the actuator sticks out into an open bay and the strut swings opposite direction, and lays over the top of a spar. The retract, if standard, would not fit in that location due to the spar interference. I do note that in the "Electron" product description, it says "these retracts are reversible"... I'm not sure of that means you can take them apart and physically re configure them to be reversible in the way a "Robart 550/530 Reverse" is set up in a reverse way or not. I'll call Dreamworks and ask.

I had not thought about this possibility before however, and thank you very much for bringing it to my attention.

Quote:
Originally Posted by Chris True
My T-33 has 550's, with the set of 8,000's I use most often it is somewhere between 20 &21 pounds. I think you'll be fine unless you operate from a cow patch grass field.

I'm also using the 7/16" struts which have been fine, the orig. 3/8" struts were not - they were bent after a few flights.

Question - were the originals aluminum frames? Robarts are steel which would be stronger if the frame thickness is similar...
Good intel for sure, thanks Chris. The Tamjets A-4 gear are 7075 Aluminum, per Tam. I'll have to check the thickness of the retract material and I've tried to call Robart for some idea of how thick the 550/530's material is. Good to know Robart uses steel. Makes me suspect they are way under rated on spec.

I have the 600 series Robart electric retracts is a scratch build jet that weighs over 25 pounds but those gear are huge... no way will they fit in the A-4 and I think the metal thickness is pretty thick so I wonder if that will go for the 550/530's too. I'm using Robary 7/16" struts in the A-4 as of now. Sine I fly off asphalt the struts are only stressed on landing, and I land about 20 pounds max even though I take off at 24 to 25 pounds. The struts have been bullet proof for the life of the model.
Jun 28, 2017, 12:55 PM
Registered User
Hmm, maybe I misspoke on the steel part: "Constructed out of high quality aircraft grade aluminum. The 550 Series Retracts are designed to replace other manufacturers retract systems and are the strongest retractable landing gear in the industry for this size."

In any case, its tough stuff if it is aluminum. I'll throw a caliper on the side plate this evening.
Jun 28, 2017, 01:39 PM
Jim H
The Electron's are reversible, IE they can be configured as your jet requires.
See the video on this page...
https://www.electron-retracts.com/reversible-version/

Jim H
Jun 28, 2017, 02:59 PM
Registered User
Side plates are aluminum, thickness a smidge over 1/16"
Jun 29, 2017, 12:53 AM
Official Boat Bum
Eddie P's Avatar
Guys thanks so much, all replies have been very helpful! I'm crunching some numbers now on what units will fit best...

Edit:

Based on a lot of your suggestions I've looked into the Sidewinder Pro Drive retracts from Dreamworks in addition to the Electron and other types. I think based on initial data, the Dreamworks Pro Drive Sidewinders with the Xicoy controller, along with the Xicoy electric brakes seemed like the ideal fit. However, it looks like the electric versions "are NOT" reversible. Chris at Dreamworks was good enough to check it out for me before I purchased. I might be going with some Robarts instead.
Last edited by Eddie P; Jun 29, 2017 at 11:07 AM.
Jun 30, 2017, 06:50 AM
Registered User
Quote:
Originally Posted by Eddie P
Guys thanks so much, all replies have been very helpful! I'm crunching some numbers now on what units will fit best...

Edit:

Based on a lot of your suggestions I've looked into the Sidewinder Pro Drive retracts from Dreamworks in addition to the Electron and other types. I think based on initial data, the Dreamworks Pro Drive Sidewinders with the Xicoy controller, along with the Xicoy electric brakes seemed like the ideal fit. However, it looks like the electric versions "are NOT" reversible. Chris at Dreamworks was good enough to check it out for me before I purchased. I might be going with some Robarts instead.
Too bad the Sidewinder isn't reversible, Dreamworks should consider making a reversible trunion.

I have the Robart 550RS in a pneumatic and the Sidewinder electric gear. They are similar in size, the primary difference is the thickness of the frame material. I measured the side plates on both. The Robart 550 averages .099" , the Sidewinder averages .116". The other striking difference is how the mounting lugs are created. The Robart frames are formed by bending , whereas the Sidewinder appears to be a machined extrusion.

Richard
Jun 30, 2017, 03:19 PM
Official Boat Bum
Eddie P's Avatar
The Sidwewinders are milled from a piece of aluminum from what I gather. Very strong. I was ready to buy but fortunately Chris at DR went the extra mile and checked before completing the order. He says the trunion and the jack screw interfered during the extension cycle. He will update the web site to show non reversible in the electric configuration.

I called Robart and got one of the engineers on the line and he was very helpful in having a look at my particular circumstance in regards to using the low profile 530 RSE's. I know I'm on my own as I am willingly exceeding the recommendations by a non trivial margin but he was pretty confident I'd have the same results as CT (seen above) flying off asphalt as long as I'm using suspension struts. So I purchased the Robart set, and hopefully they will ship soon.

I'm going to make an order with Gary at Efflux next week for some JP wheels and brakes to complete the conversion to all electric. I'm pretty excited to finally get this done, I've been limping along with some pneumatic issues for a few seasons, and the last flights recently I flew with the gear down and locked the whole time. Not cool! But way cool having some new legs and shoes on the old girl next time out flying.

Thanks again everyone for your thoughts and data!
Jun 30, 2017, 06:02 PM
Registered User
You'll be fine. The 33 is not the easiest to land. So, my landings are a mix of 1/3 greasers, 1/3 skipped due to too much speed and 1/3 full stall with a drop from 6". No slamming it into the runway but not all smooth as a feather <g>.
Jul 01, 2017, 06:37 PM
Official Boat Bum
Eddie P's Avatar
Thanks again Chris. The A4 is really soft on her feet. The modified delta wing makes touch down gentle and pretty well consistent every time. Since I fly off pavement it's even more straight forward. I will post some photos here when complete.
Jul 01, 2017, 08:49 PM
EDF all the way!
bruff's Avatar
The Electron is machined also and the brakes are incorporated into the retract box. When the retracts are up the brakes and nose steering are turned off.
Bob
Jul 02, 2017, 01:53 PM
Official Boat Bum
Eddie P's Avatar
I agree... I really wanted the clean installation the Xicoy controller gives with an all in one solution (gear, doors, brakes). From the measurements the Electrons were either too small or too large and the Sidewiners were perfect but not reversible in the electric configuration... so I had to go a la carte with Robart. At least this solution is cost reasonable and footprint possible!


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