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Robart 615 rotating retracts

Old 07-02-2002, 07:05 PM
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GalenC
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Default Robart 615 rotating retracts

I know I just need to grease my landing better, but is there any ideas out there on how to beef up the folding arms on these??? After two rough landings, the gear folds back and the arms are bent. I have the robo struts and am on a grass field. I have new ones coming in the mail
Thanks GalenC
Old 07-02-2002, 09:39 PM
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L454S
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Default Robart 615s

To avoid product bashing, I will just say these things need to be re-engineered as they dont hold up well.
Old 07-02-2002, 10:46 PM
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Default Robart 615 rotating retracts

I have the same trouble. I fly off pavement and even a small bounce folds them up. The only way I can get a landing and not trash a prop is to 3 point and take the stress off the main gear.
I hate these gears and wish someone would make a strong .60 size rotating gear.
Hans
Old 07-03-2002, 12:17 PM
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Default Robart 615 rotating retracts

Oh no. I just ordered the functional oleo's hoping it would help with this problem on my corsair. Oh well whats another 70 dollars down the robart 615 black hole
Old 07-03-2002, 01:10 PM
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lnorris
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Default YIKES!!!

Ok, putting the finishing touches on a P-40, all ready to go out to the field this holiday weekend for it's maiden flight. I've already been cursing the 615's, but now I'm really worried. I fly off a rough grass field and this gear was recommended because of their strength.

The bind SO easily and don't have real fluid motion. They tend to wait until pressure is built up and slam up or down. I was hoping they'd loosen up with usuage.

Anybody have any suggestions (other than to be sure and grease the landings)?
Old 07-03-2002, 03:37 PM
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GalenC
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Default 615 parts

I called Robart and ordered just the arms. $6.50 each or 13 a wheel or 26 a bounce. I have only three flights on the plane, greased one no problem, and bounced the other two. I am able to bend them back straight enough for use but I imagine that will only last so long. Pretty sure my P-40 is between 8 and 9 pounds so not real heavy either.
Old 07-03-2002, 07:07 PM
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Default Robart 615 rotating retracts

You could order CJ retracts from me, with 1/2" struts.
attached is a picture of the standard CJMCenturion gear with standard sized struts on a top flite jug

Ray
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Old 07-03-2002, 10:55 PM
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Default Robart 615 rotating retracts

And this is the same CJM Centurion mech. with 1/2in struts on a Giant Scale P-47. This gear has already shown its metal, by standing up to a very hard landing with just a light bend of the upper mech, no bending of the struts whatsoever. In my opinion this is the best solution if your plane is in between sizes, and or you need a little more ummph out of the struts for hard landings and or grass operations.

Ray
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Old 07-03-2002, 11:14 PM
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L454S
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Default Retracts

I think if I did another Corsair, P40,I would check out the gear from CJ. Its not the strut, but the folding and rotating mechanism that easily fails.
Old 07-04-2002, 02:44 AM
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lnorris
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Default Robart 615 rotating retracts

Well, I'll let you know how it goes. Hopefully the weather will clear so I can fly it (currently hinging it)...

I've heard good things about Spring Air but they don't make rotating one yet so...
Old 07-07-2002, 03:54 PM
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Default 615

Made 4 or eflights yesterday. Worked hard at making sure the nose was up and as much speed as possible was bled off. Greased one in no problem and had a bounce on the second one, still no problem with the nose up. The third the gear on the rotating mech popped out and the fourth the one gear bound up in the air so did a wheels up landing-no damage. I think the keys are to have a steep approach down to the one foot level, chop the throttle and keep the nose up on the flair, even if it means adding back some throttle.

I was wondering- on my trainer I baked in the oven the piano wire gear at 500 degrees for an hour and then shut off the oven and let them cool. Made them harder to bend. Would this work on these folding arms?????

GalenC
Old 07-08-2002, 02:20 AM
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tivey
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Default 615 rotating retracts

I too have the 615 rotating retracts on my tf 60 size corsair.I have 6 landings on them and havn't been able to pull up the gear since third flight for fear of not coming down.The arms have folded and been straightened as good as possible but still don't work.I had trouble with them before even the first flight.The retracts are engineered so that if they are tight enough to keep the rotating mechanizm from disengaging on landing then they are too tight to operate properly.I have been very disapointed with them.I have $200 or so invested in the retracts and struts and wish I had to do all over again.I would buy a different brand for sure.My original v/s airvalve had to be returned to robart because it didn't function properly.I hate bashing a company on the net.I really do,but they have been selling these long enough to make them correctly by now or do away with them.Just my opinion.Tivey
Old 07-08-2002, 07:43 PM
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Default Robart 615 rotating retracts

I'm building a TF Corsair with the Robart 615's and this thread is making me nervous.

Typically we hear more about the bad experiences of a product and very little about the success stories. I have no experiences with this product yet, but I was wondering if anyone out there has something GOOD to say about Robart #615?

(I'm just looking for a little peace of mind about this)

Juice
Old 07-08-2002, 09:54 PM
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GalenC
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Default 615

Out of the first 7 flights, my gear have only failed to retract once, and that was after the rotating gear mech popped out and I didn't run them up and down a couple cycles to check them. Otherwise, I think the installation is key to not bind the frame in anyway. Also, I have only about a third of the tire showing ahead of the leading edge. I've read where you should have at least half of the wheel in front of the leading edge as you look down form above. So I may try adding a couple washers or something to the back of the frame to increase this.

Any other ideas????
GalenC
Old 07-09-2002, 12:47 AM
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Default 615 Maiden Flight

Well, the stars aligned for me today and I was able to go out and fly my Direct Connection P-40 today. The plane flies GREAT!!! No bad habits, stalls VERY slowly and just gently dips the left wing. Need to cordinate the turns a little to make them pretty but it flies WONDERFUL!!

Ok, I fly off of a grass field. A rather rough (and short) grass field. I have half of the wheel exposed when looking down (past the leading edge) and had no nose over tendencies. The plane is 8.5 lbs and has a Saito 100 pulling it with a 13x8 three blade prop. The first flight I did I didn't touch the gear and left them down the whole time. The second flight I retracted them and they retracted fine. I put them back down after having a blast doing high-speed fly-bys and did a gear check pass and they came down and looked good. Landing was a little bouncy (no oleo struts yet) but they held and it taxied well.

Ok, my thoughts are this. I spent weeks making sure the retracts didn't bind. The Top Flite instructions even say to screw the retracts to the blocks BEFORE glueing them in. Wish I had done that. Second thing is to make sure the wheels clear the wheel wells with room to spare. Then make sure you file a good enough flat spot where the top two screw touches the strut. Last is make sure your wheels are pointed straight ahead. I thought about toeing mine in but didn't want the side load that would generate on the gear.

Oh, and they worked better after they got a little oil on them. I also set the bleed screw to put the gear up slowly but sling them down as fast as possible. The arms won't lock if done slowly.

ALSO, I noticed when I got mine a couple of months ago that they stuck a bit at the up and down positions. I called Robart and was told that they had a small problem with the machineing and to send them back. I did and when I got them back (in just a couple of day I might add), they worked MUCH better.

I'm not saying they won't fail on my next flight but so far, I pleased....
Old 07-11-2002, 02:34 PM
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Default Robart 615 rotating retracts

Originally posted by Juice
I'm building a TF Corsair with the Robart 615's and this thread is making me nervous.

Typically we hear more about the bad experiences of a product and very little about the success stories. I have no experiences with this product yet, but I was wondering if anyone out there has something GOOD to say about Robart #615?

(I'm just looking for a little peace of mind about this)

Juice
Well guys,
I have had these 615's in two planes, a Jemco Hellcat and Corsair
And I never had the problems that you all describe.

Although, the set up of these gear is very critical to their smooth operation!!
If the rails they mount to are not perfectly parallel they will bind and slam up and slam down.
The best trick I found is to epoxy the mounting rails in with the gear attached so you know they are strait with the gear.

Also very important to use a regulating valve to slow the retract movement in both directions.

I'll continue to use the 615's

BTW?
Aren't those planes a little small for a grass runway?
and bouncing landings I can't help you with.
But just to say practice practice practice and carry a little more speed over the apron

At least you guys a building cool planes
Good luck!!
Old 07-12-2002, 04:02 PM
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GalenC
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Default 615

I hope nobody thinks I was only out to bash the product. I got two more flights in the other night. Figured out why the rotating gear was popping out (loose screws on the back of the arm) and the second landing was slowed down and in and no problems. So in the first 9 flights on my Direct Connection P-40 the gear has only once failed to come down (my fault), 3 successful, and 5 bent arms. I have bent them back straight the best I can and they still operate. I think the key is to bleed your speed off a foot or less off the ground until you have full up elevator, add back some throttle if you have to - but keep the nose up, and it can handle some bounce. If you 'fly it to the ground' all worried about tip stall, they will bend back no matter how smooth you touch down.

GalenC
Old 07-12-2002, 04:47 PM
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lnorris
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Default Robart 615 rotating retracts

GalenC,

You know I've been reading and responding to all this and JUST noticed that it was you. Hey, you've got to post or send me some picts of how it turned out!


Mine is flying great. Haven't finished it yet (still have a lot of detailing to do) but that'll come with bad weather... ;-) I had a "warbird" guy talk me through it's maiden flight and I've been keeping the speed up on the landings which has been a bit bouncy but no gear failure/bending.

BTW, since you got your retracts at about the same time I got mine, you may want to check and see if the cylinder is binding at the top like mine where. If so, call Robart..
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Old 07-15-2002, 12:22 AM
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Default Finally bit me

Well I finally bent one of my arms. Was flying it today (5th flight) and there wasn't any wind. So I was coming in rather fast and touched down smooth but had to turn hard to avoid hitting the fence (we have a short field).

Also noticed that the wheel that was bent was the one with a slight toe in. I'm going to fix the arm and straighten the toe in and hopefully that'll fix it.

Oh, and bleed off more airspeed. These Direct Connection P-40's can fly pretty slowly so..
Old 07-15-2002, 05:30 PM
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Default Direct Connection P-40

Larry-
Wow! Nice plane. I've have taken some pics of mine but not sure on getting them online. Need to pick them up today. Did have a lady get some pictures of it Sunday at a fun fly and they are suppose to be put on a web site so will let you know if that happens. Bent the folding arms taxiing out for take-off. We were not at our field but at a newly made soccer field so was quite bumpy. The plane flys great after my thumbs have adjusted to it. Using the right thumb only it likes to keep on rolling over. Looks better and is easier with smaller but equal amounts of rudder and ailerons. Then elevator. Need to do the stall test yet and then maybe try a loop and a slow roll. 9 flights so far. Still waiting to get the new arms I ordered from Robart. Will keep bending the old arms back till they break or don't work.
GalenC
Old 08-05-2002, 02:30 AM
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Default Robart 615 retracts

Called Robart a few days ago about these retracts having such weak folding arms.He told me they had some get out of the factory without being tempered.I returned mine to them and they sent me a new set.The new ones seem to be much stiffer and stronger.Thanks Robart.Tivey
Old 08-05-2002, 05:41 AM
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Default Robart 615 rotating retracts

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Old 08-05-2002, 12:26 PM
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Default Robart 615 rotating retracts

Last fall.Somewhere around October.I bought from a local hobby store who ordered from Robart.Tivey
Old 09-04-2002, 01:55 PM
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Default Robart 615 rotating retracts

I have a TF P40 with the Robart 615 Retracts. On the first attempted flight the linkages bent before I got off the ground. I have replaced the linkages and the new ones are much stronger and have not bent since. Now I have a problem with the rotating mechanism jumpng teeth on on landing. The gear linkages hold and the gear stay extended but rotate 90 degrees and cause an immediate stop and nose over damaging the cowling.

I have serviced them after each occurance and have found everything to be tight and properly assembled with the exception of the mechanism having jumped two teeth. The only thing to do is to disassemble the gear enough to realign the jumped teeth in the rotating mechanism.

Have any of you experienced this?

I have a feeling that this gear cannot handle grass fields.

Is their a heavier duty gear that could easily replace the Robarts that don't require modifying the wing?
Old 09-04-2002, 02:08 PM
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lnorris
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Default Robart 615 rotating retracts

I've been flying mine off a grass field without problems. The only bent arms I've had was when I made a sharp turn at the end of the field to avoid a fence.

I've never had the gear jump teeth though. I've got to think that either your set is not built right or something isn't tightened properly.

BTW, how heavy is your P40? I've heard many of these coming out over 10 lbs which is, I think, the upper limit of what these retracts where designed to handle.

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