Retracts

[Andy J]

Fed up with cheap servo-less retracts on my Warbirds Hurricane as they seem to come lose after every flight or break after a firm landing, so I need to replace them with a better product. Unfortunately HK are out of stock on all metal versions so I did ponder if pneumatic retracts are a better option as all seem to use metal frames and mechanics. No past experience using pressure operated devices so is this just another item to cause me issues?

[Jon H]

My YT La7 is over a decade old and has suffered 3 or 4 retract failures in that time, all in its first 5 years of use. One was a servo failure on the operating valve and the others were loss of pressure due to dirt in the filling valve and my pre flight checks now check this more closely and i now catch the problem before i fly. In all cases a belly landing was performed with a minimum of damage, often flying again the same day. 

 

Air retracts get a load of bad press due to leaks/failures but as with most things in this hobby correct installation and maintenance are essential. 

 

In the case of my YT models and any retracts originating from china i strip the units down, clean them, grease them up and put them back together with threadlock and test them for smooth operation. Once in the model i gas them up, wait 5 minutes, retract the gear, wait 15 minutes, and then lower the gear. If they come down nicely they have passed the leak test and its off to the field. I know some like to leak test their retracts for hours and my only comment about that is why? A flight is rarely more than 15 minutes and as long as you have enough air pressure to get the up locks out gravity will do the rest. 

 

I am also not worried about a gear up landing. Its inconvenient, but not something to be scared of and its very unlikely to do major damage. If you watch youtube videos of people doing gear up landings you will see a large number would be considered awful approaches even if they had wheels. I think people get in a panic about damaging the model and their flying suffers as a consequence. This usually manifests as being afraid of the ground, trying to flare too high and then stalling causing the model to thump onto the ground causing more damage than landing normally. Just accept that its a gear up landing, shrug your shoulders, and land. I tend to kill the engine once i know the runway is made and just before touchdown flick the flaps up to prevent damage. 

 

 

Anyway i like air retracts and have them in 4 models currently with at least 5 more that will have them in future. I have one set of electric retracts in my sea fury and they have let me down once in its 8 years of service. They are more of a faff to use and set up though but the main issue with them is the controller is a bit donkey. Some decent electric retracts from electron are likely to be ok and i will probably get some in future to try in one model or another. 

 

Certainly i would take a cheap set of air retracts over a cheap set of electric ones as most ills in an air retract can be cured with a clean or a new O ring or something. Trying to sort out a half dozen tiny brass gears is another story. 

 

 

 

 

[Paul De Tourtoulon]

You can get the HK all metal ones on ebay, I have around 6 paires of them, 'if' installed properly the don't fail ( mine dont )

 even the ones that I have altered to twist and turn.

https://www.ebay.fr/itm/252207148201?var=0&mkevt=1&mkcid=1&mkrid=709-53476-19255-0&campid=5338343603&toolid=10001&customid=eb%3Ag%3Avms%3Aeb%3Ap%3A252207148201%3BCjwKCAjwmJeYBhAwEiwAXlg0AbJb98aquzd3rD4c2Xm45s4yCDgzlJEx5mDhHCOCJy89ELu_w1TYkxoCuywQAvD_BwE&gclid=CjwKCAjwmJeYBhAwEiwAXlg0AbJb98aquzd3rD4c2Xm45s4yCDgzlJEx5mDhHCOCJy89ELu_w1TYkxoCuywQAvD_BwE

 

 In my Rafale I have some old Robart air up spring down even if they leak they come down, you can get the same ones from spring air.

 

 only $125 for the 20lbs ones.

 

https://springairproducts.bigcartel.com/product/1-5-scale-403-90-deg-complete-set-for-20-lbs-planes

Edited August 24, 2022 by Paul De Tourtoulon
a

[Nigel R]

In the true spirit of answering a different question... if set up right, then plain old mechanicals are very reliable. You've probably already got the second battery / switch installed? Setup is not that onerous, mainly coming down to getting the travel right (i.e. using the right servo disc).

[richard dalgleish]

Talking to some jet flyers at the weekend, these Electron retracts are considered the best when it comes to electric ones.

 

Home > Electron Retracts (electron-retracts.com)

 

If you want air operated go with Sierra.

[GrumpyGnome]

I'm assuming if I wanted to use one channel and a separate battery, I'd need 2 Y leads?

 

 

 

Question for you.... if I have each mechanical retract on a separate channel, any idea how I'd use a single separate battery ?

[Jon H]

56 minutes ago, GrumpyGnome said:

I'm assuming if I wanted to use one channel and a separate battery, I'd need 2 Y leads?

 

 

 

Question for you.... if I have each mechanical retract on a separate channel, any idea how I'd use a single separate battery ?

 

All you need to do is remove the red wire from the plug connecting your retracts to the rx. Keep the ground common and all will be fine. 

[Bruce Collinson]

I have two sets of E-flite electrics in F3A planes and despite being Chinese they seem well engineered, and less costly than Electron.   If there’s going to be a weakness it will be in the cheesium main leg wires which will be replaced when bent, although getting hold of properly tempered piano wire seems to be a separate challenge.

BTC

[Alan Gorham_]

E-flite units have a long history of one of the control units giving up on many forums with international contributors. Not sure I'd use them with confidence based on the reports.

[Allan Bennett]

My recent experience of electric retracs is with the ones sold by 4-Max for TN's models.  I've managed to crash a couple of them so badly that the short leg connecting the oleo leg to the retract mechanism has bent badly, but the retract mechanism and oleo have survived in each case.  I replaced the bent legs with chrome steel rod from Chronos, on the advice of a fellow club member who's into metalworking.

[Frank Skilbeck]

Bear in mind if you have a largish airtank, you wouldn't want to pump them up with a hand pump 😄

 

Generally we've found air retracts to be quite reliable, I had a small EDF about 10 years ago with a set of mini air retracts, they would hold pressure from one week to the next. Only problem we did have was on a set for a YT Bonanza, there was a fault in one of the cylinders that allowed the air to leak out, we managed to fix it and they were fine after that.

[Andy J]

Given up on the concept of using air retracts as looking at the types available they work out a fair bit more expensive than a set of electrics.  So I have put an order in for an all metal servo-less retract unit which is slightly larger than the type I have been using, so no doubt  a bit of gouging out of the wing will be required.

[Andy J]

Well having now received the new retracts some machining of the oleo pin will be required given it is 10mm. Unfortunately I cant see how the pin can be removed. Certainly there was a grub screw on one face of the mounting block that pivots but having removed the screw this has not released the pin. So has anyone else played with these types of retracts before and can advise how the pin is extracted.

Certainly the assembly can be split but don't particularly want to do that to avoid damaging any of the mechanics.

[Andy J]

Problem solved. Removed the mounting plate and this gave access to two more grub screws.

[Paul De Tourtoulon]

Good luck with them they are good solid retracts.

[Ian Wilson 10]

Andy: What is the make/brand of the metal retracts? Who did you  order them from?

[Paul De Tourtoulon]

I don't know about Andy, but these are the old HK units I get mine from ebay.

[Andy J]

Ian they came from : https://www.ebay.co.uk/itm/172350465742?hash=item2820e366ce:g:Zz8AAOSwxkFcChb2

[Artto Ilmanen]

On 24/08/2022 at 11:35, Jon - Laser Engines said:

My YT La7 is over a decade old and has suffered 3 or 4 retract failures in that time, all in its first 5 years of use. One was a servo failure on the operating valve and the others were loss of pressure due to dirt in the filling valve and my pre flight checks now check this more closely and i now catch the problem before i fly. In all cases a belly landing was performed with a minimum of damage, often flying again the same day. 

 

Air retracts get a load of bad press due to leaks/failures but as with most things in this hobby correct installation and maintenance are essential. 

 

In the case of my YT models and any retracts originating from china i strip the units down, clean them, grease them up and put them back together with threadlock and test them for smooth operation. Once in the model i gas them up, wait 5 minutes, retract the gear, wait 15 minutes, and then lower the gear. If they come down nicely they have passed the leak test and its off to the field. I know some like to leak test their retracts for hours and my only comment about that is why? A flight is rarely more than 15 minutes and as long as you have enough air pressure to get the up locks out gravity will do the rest. 

 

I am also not worried about a gear up landing. Its inconvenient, but not something to be scared of and its very unlikely to do major damage. If you watch youtube videos of people doing gear up landings you will see a large number would be considered awful approaches even if they had wheels. I think people get in a panic about damaging the model and their flying suffers as a consequence. This usually manifests as being afraid of the ground, trying to flare too high and then stalling causing the model to thump onto the ground causing more damage than landing normally. Just accept that its a gear up landing, shrug your shoulders, and land. I tend to kill the engine once i know the runway is made and just before touchdown flick the flaps up to prevent damage. 

 

 

Anyway i like air retracts and have them in 4 models currently with at least 5 more that will have them in future. I have one set of electric retracts in my sea fury and they have let me down once in its 8 years of service. They are more of a faff to use and set up though but the main issue with them is the controller is a bit donkey. Some decent electric retracts from electron are likely to be ok and i will probably get some in future to try in one model or another. 

 

Certainly i would take a cheap set of air retracts over a cheap set of electric ones as most ills in an air retract can be cured with a clean or a new O ring or something. Trying to sort out a half dozen tiny brass gears is another story. 

 

 

 

 

 

I just installed ESM air retracts on my ESM Focke Wulf 71" - at 85psi plenty of power to operate the gear even with the original ESM wheels that are quite heavy. But, I seem to have some leaks so I need to sort them out. I already moved the air tank from the fuse on the wing so I was able to get rid of the air connectors between the fuse and the wing (another source for leaks). Anyways, carrying out maintenance of the air cylinders is ok but can you do anything with the ESM air valve? (see picture)

 

Or, are you gents replacing the ESM air valve with a more quality stuff, such as Robart air valve etc?

 

 

[Artto Ilmanen]

1 hour ago, Artto Ilmanen said:

 

I just installed ESM air retracts on my ESM Focke Wulf 71" - at 85psi plenty of power to operate the gear even with the original ESM wheels that are quite heavy. But, I seem to have some leaks so I need to sort them out. I already moved the air tank from the fuse on the wing so I was able to get rid of the air connectors between the fuse and the wing (another source for leaks). Anyways, carrying out maintenance of the air cylinders is ok but can you do anything with the ESM air valve? (see picture)

 

Or, are you gents replacing the ESM air valve with a more quality stuff, such as Robart air valve etc?

 

 

 

Ok, I tested the system for leaks and it is the air valve which is leaking. I need to dismantle it and see if it can be fixed. Or, alternatively, I need a replacement air valve

[Jon H]

The esm valve is a very simple design using a small rubbery flap with a spring behind it. This design is very vulnerable to the ingress of dirt and/or any imperfection in the mating surfaces inside. On mine i deburred the hole on the inside and placed a very thin washer between the spring and rubber pad to prevent deformation of the pad by the coil spring. 

 

WHen it comes to leaks, dont worry too much. If you pump it to full pressure, wait 3-4 minutes, retract the gear, wait 15 minutes and select gear down. If they come down its fine as you just simulated an entire flight from pre engine to start to the beginning of landing approach. I see some guys looking  for perfect sealing after 20 days and at least 20 cycles before running out of air...why? You only cycle the gear once and you only fly for 10 minutes so test it to those requirements + a little margin for safety. 

[Artto Ilmanen]

Thanks Jon, 

 

Mine is leaking very bad - the pressure drops from 80-90 psi to about 30-40psi in 3-5 seconds. If I wait for 30 seconds I barely get the gear up. 

 

I’m using the standard ESM air tank which is smaller than the Robart one. But, I believe it’s ok as long as I get the leaks (air valve) sorted out so the gear performs in a manner as you write

 

If I can’t fix the ESM valve, then, what might be options for replacement valve? a Robart blue valve?

[Artto Ilmanen]

This is my ESM air valve (at least I think this an ESM one)

 

This thing just has 2 O-rings doing the job - no spring whatsoever. I tried to apply grease but no help. Maybe new O-rings could help, I dunno..

 

 

[Ron Gray]

Oops, wrong valve, I thought you meant the filler valve, so deleted my post!

 

 

 

Edited March 25, 2023 by Ron Gray

[Artto Ilmanen]

Sorry Ron - not being a native speaker I may have used a wrong word here, although I do have seen others using the same word for the valve that controls the gear system. Anyways, the air control valve I’m having is causing issues and I wonder if it is worth the efforts to fix it or should I just shop a new better quality one (which?).

 

As this is my first air retract project I’m pretty much in learning phase