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Arghh Retracts, electric just as likely to fail as air.

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Old 08-19-2013, 01:39 PM
  #1
DiscoWings
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Angry Arghh Retracts, electric just as likely to fail as air.

To those thinking electric retracts will solve all the problems with air, think again. Yesterday I had a crash / skid / scrap landing because my Behotech e-line C-50 failed to deploy on 1 of my mains, it would come down half way and lock up. Despite cycling it multiple times to try it break loose it made no difference, finally I had to belly land scrap land the jet.

My confidence on electric retracts is now falling seriously, as I have had issues with all 3 lines of major e-tracts mfgs:

1, Down & Locked: motors are under powered and have hard time retracting gears in flight, this only seems to affect planes 45 lbs and over, I know the FEJ 1/6th gear are too big for the D&L conversion.
2, Electron: under powered even at 7.4 volts, same issue as down & locked, once the gear gets heavy it stalls. ER-50 starts to wuss out on large F-18 gear.
3. Behotec, drive failure or lockup, these seemed like the strongest out of both D&L and Behotec, however, there appears to be some gear train problem, I can't get this c-50 to open up any more, it open ups hafl way and binds... I'm guessing something stuck in the thread screw drive (even though the Behotec is fully sealed)

I'm about to just go back to air, or try hydraulic conversion retracts as electric retracts aren't the magic pill that solves all the problems.

So far about the only things that have been reliable are the small e-flite retracts for 70mm-90mm edfs, yet even those are having problems.

How many of you guys have been using electric retracts, what are you thoughts?
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Old 08-19-2013, 02:48 PM
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Never had any problems with my electric retracts -
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Old 08-19-2013, 02:59 PM
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Are you using this or similar?

http://www.bvmjets.com/Pages/Catalog/dryice.htm
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Old 08-19-2013, 03:29 PM
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My down and locked on the 1/6 f-16 worked just fine once I got the proper voltage. They have new motors that are about 20% stronger, and if they dont come up they always come down unless they are binding. Nothing is a 100% but I think electric is better than air with complex gear like this.
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Old 08-19-2013, 03:39 PM
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I have 150 flights with my D&L gear. Had to have them make a current trip adjustment after first few flights been great since. I am sold on them. I have them on 3 different planes.
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Old 08-19-2013, 04:17 PM
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I got Down and Locked working perfect on 2 giant gear 55lbs and up. My gear can lift 10lb weights! I also have them on my Shockwave and they have been perfect.
Takes a litte work sometimes to get them there, but with a little patience you can have much success.
Different batteries work better than others and some require certain voltages.
You need to sacrifice speed for strength and run the highest voltage allowed and 35C or higher battery.
Scott
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Old 08-19-2013, 05:28 PM
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Personally I have never thought that electrifying retracts would be the panacea to all retract issues. I've always thought electric retract is a solution to a problem that shouldn't exist.

I think the big push for them to be developed came about because of the general unreliability of Asian pneumatic systems, which suffered from numerous leaks and undersized cylinders. Electrics solve these issues as they are very powerful, and of course they never leak. Electrics do however have other weaknesses which need to be managed. No system is perfect.

I have never had an issue with air leaks, and so have never considered going electric. I have however, always used good quality (read expensive) pneumatic gear, for peace of mind.


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Old 08-19-2013, 07:13 PM
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My electrons are working perfectly. Love them.
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Old 08-19-2013, 08:58 PM
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Are you saying your C50 problem is 100% due to an issue with the drive shaft?
I only ask because manual the describes how to program the gear to stop at the midpoint. Just wondering if you have a programming error or something like that going on?
http://www.altecare.com/eline1english.pdf

I'm interested in your problem because I have a set of electric C50 F's going in my next jet.

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Old 08-19-2013, 09:47 PM
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I'm not 100% sure I would need to take apart the unit, I will email behotech ask local dealer what he thinks, but the unit was working fine and all of a sudden it stopped, switched ports on the controller doesn't make a different this one C-50 E-line just opens up about 30% maybe the screw got stripped?

Pitty, out of D&L, electron I liked the behotec the best :/
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Old 08-19-2013, 11:52 PM
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Interesting thread. I too have tried electrified C50 retracts with electric actuator units from 2 other sources than the ones you mention. They too had problems. One failed on the bench several times and I just couldn't use it in the air. The other was promising but failed when used in the air for the first time. I am sure the problems a lot of us have with current pneumatic retracts is that they have not got any larger as the planes have got larger. They have to work at increasingly high pressures, and are then more likely to fail with air leaks and grit on the retract units. I have Behotec C50 units in 3 of my planes and they are excellent. However they are marginal when using a wheel of 4" or over and I have to run at 120 psi for reliable retraction. They are just too small. The next size up is the one for UAV's but they have the cylinder located backwards and I couldn't use them. I now have designed and made a set of huge pneumatic retracts based on the Behotec width footprint. They work really well at really low pressure. I will be posting more info when I have them installed in the plane.

John
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Old 08-20-2013, 01:02 AM
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I think John Wright has hit the nail on the head, bigger and bigger retracts seem to still be using the same diameter cylinder. It only takes a small increase in diameter to make a big difference to the piston area, which in turn makes a big difference to the power of the retract or the ability to use lower air pressure.
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Old 08-20-2013, 02:56 AM
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A set of ER40 Electrons here over 100 flights nil issues PST Reaction gone through 2 x sets of prolink struts however big issues with them. A set of ER50's on a Eurofighter CARF only 10-20 flights so far no problems so far.
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Old 08-20-2013, 04:58 AM
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Short struts & smaller wheels are not an issue on pneumatic or electric. Larger jets with 170mm+ struts with 100mm+ wheels at the end can be a problem.

It appears Behotec C50's can be bumped up to a 4amp max for heavy gear.
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Old 08-20-2013, 05:21 AM
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Quote:
Originally Posted by roger.alli View Post
Personally I have never thought that electrifying retracts would be the panacea to all retract issues. I've always thought electric retract is a solution to a problem that shouldn't exist.

I think the big push for them to be developed came about because of the general unreliability of Asian pneumatic systems, which suffered from numerous leaks and undersized cylinders. Electrics solve these issues as they are very powerful, and of course they never leak. Electrics do however have other weaknesses which need to be managed. No system is perfect.

I have never had an issue with air leaks, and so have never considered going electric. I have however, always used good quality (read expensive) pneumatic gear, for peace of mind.


Roger
Couldn't agree with you more there Roger. We are trying to fix reliability issues by switching technologies. In a 6S world this would be EPIC FAIL.
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Old 08-20-2013, 07:34 AM
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Love my Down n Locked. Have them in many jets. Putting them in my F-104 now and it's got large complex gear.
Nothing is perfect but I feel that once the E gear has been properly designed and setup it is more reliable and requires less maintenance than pneumatic systems.
A friend has C-50's in his big CA Viper and they are flawless!
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Old 08-20-2013, 08:05 AM
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I can honestly say that in 22 years of flying aircraft with retracts, I have NEVER had a gear failure that wasn't easily explained and user fault. The most common problem I ever had with retracts was when I was flying pattern and those long 5/32" gear legs would bend backwards on the grass a bit and I wouldn't notice, gear would go up, and get jammed in the wheel wells. Since I've been flying jets, I never had a gear failure until this year when my bobcat gear wouldn't come down. Reason, I had just replaced the nose gear flex plates and had somehow cut the air line to the down side of the cylinder, it worked when I checked them but I failed to notice the hiss of escaping air. Could have done the same thing with an electric gear in that situation, kinked a wire that until there was some vibration made enough contact that the gear would have worked in a static test.
All comes down to that age old advice of "Buy quality, buy once". I've had gear that didn't work properly, from FEJ, and the original Skymaster stuff, Never flew the aircraft with the faulty stuff so still can't call it a gear failure. I see many potential issues for electric retracts, just like there are with air. However, I've found air to be very low maintenance, very easy to install, and very problem free, so I personally have no reason to change.
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Old 08-20-2013, 10:59 AM
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Quote:
Originally Posted by DiscoWings View Post
To those thinking electric retracts will solve all the problems with air, think again. Yesterday I had a crash / skid / scrap landing because my Behotech e-line C-50 failed to deploy on 1 of my mains, it would come down half way and lock up. Despite cycling it multiple times to try it break loose it made no difference, finally I had to belly land scrap land the jet.

My confidence on electric retracts is now falling seriously, as I have had issues with all 3 lines of major e-tracts mfgs:

1, Down & Locked: motors are under powered and have hard time retracting gears in flight, this only seems to affect planes 45 lbs and over, I know the FEJ 1/6th gear are too big for the D&L conversion.
2, Electron: under powered even at 7.4 volts, same issue as down & locked, once the gear gets heavy it stalls. ER-50 starts to wuss out on large F-18 gear.
3. Behotec, drive failure or lockup, these seemed like the strongest out of both D&L and Behotec, however, there appears to be some gear train problem, I can't get this c-50 to open up any more, it open ups hafl way and binds... I'm guessing something stuck in the thread screw drive (even though the Behotec is fully sealed)

I'm about to just go back to air, or try hydraulic conversion retracts as electric retracts aren't the magic pill that solves all the problems.

So far about the only things that have been reliable are the small e-flite retracts for 70mm-90mm edfs, yet even those are having problems.

How many of you guys have been using electric retracts, what are you thoughts?
Wrote an article for RCJI...started a year ago, finished 2 months ago. Its in the next article and it says...electric gear in larger sizes is less reliable than air. Its fact.

Sure it will come, but I have people changing back to air. The original CARF Classic Flash has C-36/2 air retracts... 7 years old, hundreds and hundreds of flights...no issues. Same for just about all the systems I use.

Dave
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Old 08-20-2013, 11:07 AM
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With the Bobcat as an example you are talking about a very small well engineered and well tested design. We are moving rapidly from that to much larger planes. My Arado weighs 31 Kg so is reaching the limit of what can be bought for it. It is not just that the gear does not operate properly ie leaks, but just will not move the legs up. I am sure that you like me has seen planes flying at events where the retracts just will not work. Often you see people testing the retracts working on the ground only to have them fail to go up after takeoff. This may be due to the airflow round the doors and wheel wells, but indicates the need to have a surplus of pressure. People have to resort to very high pressures and even to inverting the plane to get the gear to do up or is it down! This seems crazy to me and it is time that we devised something better. Merely electrifying an undersized unit does not give a sensible solution either. If the unit is sized much larger then the forces used to make it work are much less. Electrifying a larger unit makes much more sense, but I would do it with much bigger motor and gearbox.

John
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Old 08-20-2013, 01:03 PM
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Ever wondered why big airplanes dont use electrical retract systems? Maybe this is why, the full scale engineers and designers have figured it out already. Granted, the king airs I fly have an electrically actuated gear system, but there are torque tubes, limit switches, gear reductions and actuators all over the place (compared to our models). The big heavy iron stuff seems to use hydraulic for everything, why arent we?
Yea i know you have to deal with leaking fluid, hard lines and the likes of it (and lets not even begin to talk about the abomination of the hydraulic system included with the Fiber lassics mig29's), but if its reliable and FUNCTIONAL, it seems worth it to me. They even have no drip disconnects for the lines now, so on those large models with wing mounted landing gear, you can still remove the wings.


I havent had any first hand experience with electric gear...yet.. Because it seems there are more problems popping up by those who use them, than problems they solve. I havent had many issues with my pneumatic retracts (other than those i caused from lack of maintenance) so i really dont understand the justification in spending $300+ to convert when the only thing it seems to benefit is the manufacturer lightening my wallet and saving a few minutes of not having to air up the gear.
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Old 08-20-2013, 01:28 PM
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Quote:
Originally Posted by invertmast View Post
Ever wondered why big airplanes dont use electrical retract systems? Maybe this is why, the full scale engineers and designers have figured it out already. Granted, the king airs I fly have an electrically actuated gear system, but there are torque tubes, limit switches, gear reductions and actuators all over the place (compared to our models). The big heavy iron stuff seems to use hydraulic for everything, why arent we?
Yea i know you have to deal with leaking fluid, hard lines and the likes of it (and lets not even begin to talk about the abomination of the hydraulic system included with the Fiber lassics mig29's), but if its reliable and FUNCTIONAL, it seems worth it to me. They even have no drip disconnects for the lines now, so on those large models with wing mounted landing gear, you can still remove the wings.


I havent had any first hand experience with electric gear...yet.. Because it seems there are more problems popping up by those who use them, than problems they solve. I havent had many issues with my pneumatic retracts (other than those i caused from lack of maintenance) so i really dont understand the justification in spending $300+ to convert when the only thing it seems to benefit is the manufacturer lightening my wallet and saving a few minutes of not having to air up the gear.
Large airplanes are now starting to use electric gear. ;-)
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Old 08-20-2013, 01:31 PM
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Quote:
Originally Posted by FalconWings View Post
Large airplanes are now starting to use electric gear. ;-)
Got an example? And dont tell me a electrically driven hydraulic pump...
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Old 08-20-2013, 02:13 PM
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Century Jet Retracts has a new line of Electrics designed for all scales of planes- and I've personally seen some of them tested in the field...They worked great and even have lighting options
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Old 08-20-2013, 03:20 PM
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Quote:
Originally Posted by invertmast View Post
Got an example? And dont tell me a electrically driven hydraulic pump...
I'm afraid it is not within FAR scope, so no, can't tell you. :-)
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Old 08-20-2013, 03:21 PM
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Quote:
Originally Posted by FalconWings View Post
I'm afraid it is not within FAR scope, so no, can't tell you. :-)
Then it didn't happen lol
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