retract servo
02-22-2009, 10:04 AM
#3
RE: retract servo
As a pratical matter most attempts to use a standard servo for retraction ends in failure.
Using a bigger wheel will help but most 'standards' are whimps when you do that with insufficient torque. Retract servos are normally much stronger. The chances are much greater of stalling a servo on retraction and excessively bleeding off you batterys current in flight. A Retract servo will travels the full 180's when keyed (they are none proportional) and stop drawing current.
I highly recommend you do it right or not at all. Saving a buck here is a very poor idea. The exception is some of the small half A mechanical retracts now coming back into the market.
John
Using a bigger wheel will help but most 'standards' are whimps when you do that with insufficient torque. Retract servos are normally much stronger. The chances are much greater of stalling a servo on retraction and excessively bleeding off you batterys current in flight. A Retract servo will travels the full 180's when keyed (they are none proportional) and stop drawing current.
I highly recommend you do it right or not at all. Saving a buck here is a very poor idea. The exception is some of the small half A mechanical retracts now coming back into the market.
John
02-22-2009, 10:48 AM
#4
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RE: retract servo
No! Don't use a standard servo... unless you don't mind landing gear collapses. Landing gear servo's are all metal geared with bearings... they are designed just for the use of mechanical retracts. So who ever says to use a standard or digital servo, I question their experience.
02-22-2009, 03:29 PM
#7
RE: retract servo
Yes Retract servos have just over 180 degrees of travel.
There is a bottom line here and that line is its almost impossible for a newbie to mechanical retracts get it right with the wrong servo. Yes it can be done however your chances of success is almost nil. To make matters worse a common senario is you are going to have gear not fully retracting or pulling out on G load and you are going to be sucking up your battery supply with an overloaded stalled servo. Thats not condusive to the life or your airplane.
Do it right or don,t do it at all is very sound advice.
John
There is a bottom line here and that line is its almost impossible for a newbie to mechanical retracts get it right with the wrong servo. Yes it can be done however your chances of success is almost nil. To make matters worse a common senario is you are going to have gear not fully retracting or pulling out on G load and you are going to be sucking up your battery supply with an overloaded stalled servo. Thats not condusive to the life or your airplane.
Do it right or don,t do it at all is very sound advice.
John
02-23-2009, 02:12 PM
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RE: retract servo
Minnflyer... that is a good servo for a .40 or .46 glow, or a light electric arf. But I too believe in the theory you get what you pay for.
I'm a big JR fan and I haven't had any problems with any of their fine products... matter in fact I endorse JR. ( Wish they endorsed me.)
If you plan on doing major work on your aircraft... and you want to make sure you hit the gear switch and behold see the gear come down. Spend $30 bucks more and you will get a good, strong, long lasting retract servo.
http://www.horizonhobby.com/Products...ProdID=JRPS791
It's good for .40 up to 1.20 sizes for planes that have some weight to it. Matter in fact I bought one for my Kyosho Fw-190... and man it has torque!
Do it right or don't do it all... yes I agree with that statement. I always seem to pay for it, if I go half arse. I second what JohnBuckner suggested.
Now if you are going all out on your plane either scale... or scale warbird and if your plane is quite large, I would get the Robart Air Retracts.
Give them a call and tell them what you have and they will send you what you need for your plane. The problem using a regular servo is you have to account for wind pressure hitting the gear when you try to extend the retract. I've seen cheap or regular servo's fail because it got bound up in the wheel well because of the airflow.
I'm a big JR fan and I haven't had any problems with any of their fine products... matter in fact I endorse JR. ( Wish they endorsed me.)
If you plan on doing major work on your aircraft... and you want to make sure you hit the gear switch and behold see the gear come down. Spend $30 bucks more and you will get a good, strong, long lasting retract servo.
http://www.horizonhobby.com/Products...ProdID=JRPS791
It's good for .40 up to 1.20 sizes for planes that have some weight to it. Matter in fact I bought one for my Kyosho Fw-190... and man it has torque!
Do it right or don't do it all... yes I agree with that statement. I always seem to pay for it, if I go half arse. I second what JohnBuckner suggested.
Now if you are going all out on your plane either scale... or scale warbird and if your plane is quite large, I would get the Robart Air Retracts.
Give them a call and tell them what you have and they will send you what you need for your plane. The problem using a regular servo is you have to account for wind pressure hitting the gear when you try to extend the retract. I've seen cheap or regular servo's fail because it got bound up in the wheel well because of the airflow.
02-23-2009, 05:13 PM
#10
RE: retract servo
LuftwaffeOberst / MinnFlyer
Both those servos are fine but beware that the higher end servo is for 4.8v only. The cheaper one can use 4-6v. I live by the JR791 when it comes to mechanical retracts in my 1.20 size planes but for smaller applications .40-.60 the RT88 is more than adequate. I test my retracts by attaching a small weight to the gear during static testing. That way I know they are going to work during flight conditions.
rgm762 -
You could help us by giving up some details of the model and type of retracts you are using. Perhaps the standard servo will work but we need to see how it is being used.
Both those servos are fine but beware that the higher end servo is for 4.8v only. The cheaper one can use 4-6v. I live by the JR791 when it comes to mechanical retracts in my 1.20 size planes but for smaller applications .40-.60 the RT88 is more than adequate. I test my retracts by attaching a small weight to the gear during static testing. That way I know they are going to work during flight conditions.
rgm762 -
You could help us by giving up some details of the model and type of retracts you are using. Perhaps the standard servo will work but we need to see how it is being used.
02-23-2009, 05:45 PM
#11
RE: retract servo
what I'm working on is a VQ P51B "40" using the VQ retracts, the only reason i asked was because i have some sandard servos lying around, money is not the problem, i was just told i could use a standard servo, but it doesn't use it's full travel
02-24-2009, 08:32 AM
#12
RE: retract servo
That servo has to squeeze into a really tight spot. If you have several extra servos you could modify one to turn 180*. But looking at the model I think the smaller profile of a retract servo will fit into the wing better, and make the retracts easier to operate.
