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Old Aug 04, 2012, 02:15 AM
Life begins at transition
Australia, VIC, Sale
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24lbs, but how many g on landing?
I can break a 24lb set of retracts with a 6lb foamy if I try hard enough!
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Old Aug 04, 2012, 06:57 AM
Hope is not a Strategy
Lojik's Avatar
Australia, VIC, Caroline Springs
Joined Apr 2011
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Quote:
Originally Posted by Odysis View Post
24lbs, but how many g on landing?
I can break a 24lb set of retracts with a 6lb foamy if I try hard enough!
agreed landing does play a huge factor, although I'm sure Jurassic would have let us know if he landed hard at all.
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Old Aug 04, 2012, 08:00 AM
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It would be nicer if these cut from better alloy but I haven't been following wing span close enough to tell if Jurrasics failure is a consistent problem or poor batch. Looking at the picture it would take a very serious 24lbs to share an L joint like that, or it may be a poor alloy mix they chose or even mixed that day.

But not counting chickens, CS doesn't make PZ, PZ doesn't make WS etc so till we test them and see how the materials they've made them from hold up, its hard to assume how far off from spec they will be glancing at a picture.

We know this comparing CS, PZs and Eflite in some weight classes. They have different fail points and cost a fraction of the other.

Till then.
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Old Aug 04, 2012, 08:07 AM
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United States, WI, Chetek
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Quote:
Originally Posted by Odysis View Post
24lbs, but how many g on landing?
I can break a 24lb set of retracts with a 6lb foamy if I try hard enough!
This is true. However, there should a be a load factor element designed into products such as these. Nobody is going to have a perfect landing every time. I would consider a product of this caliber to have a considerable load factor built in. Not sure what the number should be but 2-2.5 load factor would be a minimum in my book if I owned the company.
I recently talked to Larry Epifanio from Southeast Model Products. I was looking at him building a set of retracts for me and when I told him about my issues he told me "if you break one of my retracts, the retract will be the least of your worries" meaning my airplane will be destroyed before his retract fails. Now THAT is what I need.

Quote:
Originally Posted by Lojik View Post
The problem is wingspan are advising customers that their retracts are capable to 24lbs or atleast that's what I got told on email, this is realy proof that they are not up to the task, i'm glad I saw this although I feel for you Jurassic I am glad you posted this as it tells me they are no where near capable of 20lb models.
If you, or anyone else, has an email stating such a claim I would love to see it/have it. Michael is now claiming that they are designed for only the weights listed in Top Flite's manual for the B-25 which is 17 to 19 lbs. He knew, however, when I ordered them that my target weight was at least 21 lbs. Please PM me with any info.

As far as landing....my landing that broke the nose gear was what I would consider a normal landing. I was floored actually when it broke. The landing that broke the main gear was definitely firm but remember, there was no structural damage to the aircraft until the gear broke. That started a chain of events that caused the damage to the aircraft.

Neil
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Old Aug 04, 2012, 08:09 AM
Life begins at transition
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3g is a standard I've seen on many aircraft.

I like the idea of punching the retract through the wing/fuse, but potentially a broken retract could save you from having to rebuild a wing after the retract punched a hole in it?
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Old Aug 04, 2012, 08:41 AM
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Actually the general weight class rating is misleading.
No full scale aircrafts landing gear is designed on gross weight alone.

I can have aircraft of given weight but have very different wing loads. A higher wing load results in faster drop rate at higher speed. Higher speed = higher torsion forces. Higher drop rate higher impact force.

The impact force is far different from static force and fly off grass or sand is very different from pavement.
So for some models you never hear any issues. Jets and Warbirds we constantly hear gear failure.
Not that this is your situation Jurrasic.

If they gave the fail rating torsional and impact, I guess it would be up to us to calculate back the kind of loads we'll fly. Then there is the entire shock absorbsion type struts we chose that takes off some of that load.
I think the retract should be as solidly constructed as possible, and leave shock absorbsion and break fail to the struts. Instead we see solid rod struts in these retracts, a design that's just not made to last any mistake.

If they posted break fail rates we would have a better sense if a given retract is enough.
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Old Aug 04, 2012, 09:32 AM
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United States, WI, Chetek
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Quote:
Originally Posted by Odysis View Post
3g is a standard I've seen on many aircraft.

I like the idea of punching the retract through the wing/fuse, but potentially a broken retract could save you from having to rebuild a wing after the retract punched a hole in it?
Actually, the retract didn't punch the hole through the top of the wing, but rather it was through the bottom of the wing after the retract broke and was sandwiched between the wing and the ground at that point. I should have been more clear on that....

Also, I am using Robart Robostruts with part of the spring removed to give the strut very acceptable shock absorbing action.

One last thought....... The wheels on this aircraft are Robart scale wheels (4" on the mains) and the hubs are made of plastic. I would have thought that the wheel hub would have shattered/gave out before I broke an aluminum mount on a gear unit.
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Old Aug 06, 2012, 08:41 PM
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So... let me get this straight - from the pics, it appears the wingspan retract is a cast alloy housing rather than CNC cut billet like the eflites? If so, that is a ridiculous design in this class and at this price. So I guess that leaves us with the uber-expensive robart electrics for the bigger planes. I wish Eflite would come out with a 120-180 class retract.

Any reports on how well (or not) the RCL "full metal" retracts hold up? I just got a couple sets from HK and they seem well made for the price, for the smaller stuff. I also ordered some of the struts from RC Skylite and am totally pleased with the quality of these units. It's nice to know that not all that comes from China is crap.

Jurassic, sorry for your troubles but you have done us all a great service reporting on your issues.
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Old Aug 07, 2012, 07:41 AM
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....struts from RC Skylite and am totally pleased with the quality of these units. It's nice to know that not all that comes from China is crap........
HK is now carrying some of the same struts that RC SKylite has, had for less. Check the landing gear section from HK.
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Old Aug 07, 2012, 12:14 PM
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Good catch Max, just saw that. A lot less!!

I got a set of the 141 "40-120" P-51 style for my H9 Mustang .40 and I'm totally impressed with the quality. Nice smooth oleo movement as well.
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Old Aug 08, 2012, 12:04 AM
Too windy to fly? Lets surf
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Athens, Greece
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The ESM warbird fliers at my field use Eurokit for their models that weigh 20+ lbs, and they sure hold up well

http://www.eurokitshop.it/Index.php?&id_lang=1

Nick
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Old Aug 09, 2012, 05:26 PM
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Those look really nice. All CNC billet.
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Old Aug 25, 2012, 10:08 PM
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United States, AR, North Little Rock
Joined Jun 2007
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is there a such thing as a low profile etract? the depth of most of my etracts seems to limit there application
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Old Aug 26, 2012, 10:11 AM
Noob with Issues
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United States, AZ, Maricopa
Joined Jul 2011
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ok guys i'm looking for a good quality, reliable and reasonable set of retracts for my dynum T28. I may be using these in future models so I want a good set. also some cool struts to go with it would be even better! Thx for your help guys...let me know...these are holding up my build
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Old Aug 27, 2012, 07:18 PM
Really?!?
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Lost ...on the 3rd rock out
Joined Sep 2001
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I'm quite sure this has been answered already but, are these retracts OK for a 3 to 3.5-ish pound airframe?

http://www.hobbyking.com/hobbyking/s...em_Small_.html

Thanks
Chris
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