speedy1379

Hello all,
I'm building a small plane. It's powered by a norvel big mig 15. Wing span is 35" and the fuse is 36". It has a profile fuse and foam core wings. So far, it's been simple and straight forward, but I am a beginner at these smaller aircraft. I need to know what servos and receiver you guys use in a plane of this size? How much torque should the servos have? I have some with 12 oz of torque but I'm thinking that isn't enough. Can some one help me? Any and all help and tips are greatly appreciated.

Thank you in advance,
Speedy

ptulmer

My Feedback: (5)

Mini's would probably be best. You may be able fit some regulars in there for less $$$. How many servos do you need. 1 or 2 for ailerons...? Determining your finished weight would be a good next step. That way you can see what your wingloading will be with each setup. Attached pic has a 36" wingspan 26" long and an OS 15la up front. 2 mini's and 3 micro's (not submicro) and a fullsize receiver and 600mah battery.

Andrew

A .15 on that size plane should perform like your name: Speedy -- unless it is very heavy.

If 12 in-oz. is the actual rated torque for your servos, I would recommend choosing another. The Hitec HS-55 is rated at 15 in-oz at 4.8 v, and while many on this forum are using the HS-55 for control surfaces, others are using the larger HS-81 (36 in-oz) on planes in the 32" to 36" range. One of the problems with the mini/micro servos is not necessarily associated with the servos capacity to generate rated torque figures as much as the ability of the gear train to sustain continued loads without shearing teeth. Also, many of us are flying models approaching the size of your plane with engines of about 1/3 the displacement. The servo choice most of us make is mostly dictated by weight and size -- a savings of 2 ounces may represent 10 to 15% of our models weight.

Unless weight and/or servo size is a real consideration, I think I would use the HS-311 standard for surfaces and an HS-81 on throttle.

There is a lot of experience on this forum -- read the posts, absorb the information and make your decision.

One thing I always try to keep in mind is "Just because it's my opinion doesn't necessarily mean I'm right!!"

the "other" andrew

William Robison

My Feedback: (3)

For planes like yours I like the Hitec HS-225 servos. They are minis, with the torque of the standard size.

This picture shows four HS-205BB servos, the predecessor to the HS-225. The plane is the Tiggerkitty, also shown as my avatar.

Bill.

XJet

I've heard people *****ing about the 225's lack of centering (do a search on RCU for the details) but I have some and they seem to work just fine.

However, I'd go for HS81s on a plane of that size. They're plenty strong enough and, if you're really worried, just get some HS81MGs

Going back 20 years ago, I used a pair of Futaba S20 servos (about 24oz-In of torque) in an RC combat wing powered by an OS45FSR. This thing went like a rocket and those servos did the job absolutely perfectly. By comparison, an HS81MG is a mule of a servo with 50% more torque so I think it will do just fine in a 15-powered ship.

Andrew

The torque on the 81's is sufficient, particularly if linkages and surfaces are free. However, for my deltas, I've switched to the 81MG's. OTOH, a lot of folks coming out of the larger sport planes might balk at shelling out $18 to $24 for a servo -- something we are somewhat forced to accept. This was one consideration I had with the standard HS-311. If size and the weight gain are acceptable, the savings of 3 HS-311s over 3 HS-81MGs is about $43 to $44.

Certainly there are execellent mini's that work well -- unfortunately, I have to routinely factor in cost in my decision making.[]

SST

My Feedback: (2)

I like the Dymond D-200 much better than the HS81.

John C

I'm building an Ace Simple Series Ultimate Bipe and am putting HS81s on all control surfaces, including one for the four ailerons. It will have a Norvell .15 for power if it ever gets here [:@]

I have used CA's hinges on the ailerons, and will use clear hinge tape for rdder and elevator, on BOTH sides , Elecron 6 Rx, and probably a 720 mah NiMH Rx battery.

Wing is done, struts are done, interplane linkages are done, tailfeathers are covered, rear of fuselage is ready to cover - waiting on Sig to ship my LHS my engine to finish fuselage front - promised in 10 days three weeks ago & Sig dosen't show them as out of stock on their ordering web site (rant!) [>:] .

MikeSell

My Feedback: (2)

My Herr P51 says it requires at least 24oz/in servos. Even with the largest recommended engine it will fly much slower than your plane.
I agree with SST Dymond D200 servos (34oz/in) are more compact than hs81s or hs85s. The dymond has a much more robust gear train that is cheaper to replace. I've used them on dual aileron servoed .40 size high speed planes.
I have a number of HS85MG servos that I may use in even more demanding situations.

I like the Hitec Electron RX but it is a little pricey compared to the Cirrus mx4 or mx6 which will also do the job.

MikeSell

My Feedback: (2)

John C:
I built one of the Ace Simple Ultimates also. Just a recommendation...replace the standard HS81s with metal gear units. Those gears don't hold up to much shock. Even better try HS85s.

John C

MikeSell,

I've got a pile of HS81s, and have only stripped the gears in one so far. If it becomes a problem, I'll consider your suggestion. Since the Norvel .15 is still backordered now for another few weeks, it will probably be Nov. before the Ultimate takes to the air (not a problem down here .

Basically, any sailplane > 1.3, <= 2 meter wingspan, I'm using HS 81s. For 100", I've used HS225s, although they are a tight fit in the wing.

Thanks, JOhn C

ajcoholic

My Feedback: (10)

I have flown HS81's in some fast 15 size planes, including my Sig WOnder with the piped Rossi 15 FIRE and that thing WENT! Its not just the servo torque but the size of the control surface as well and the speed. Bigger surfaces or faster planes generally require stronger servos. I have even run the older HS 80's on a .25 size low wing pattern style plane with good results.

I wouldnt use an hs55 on anything larger than a true 1/2A myself (up to an 049) and even then I prefer the extra oomph the HS 81's have for anything larger than an 020 really.

Just my opinion though

AJC

Bipe Flyer

I would go with at HS81s or HS85s.

I've run HS81s on the ailerons in 2 Golden Oldie 20s; one with a .40LA and the other with a .35FP. Both planes originally had standard servos and torque rods, but the barn door ailerons fluttered so I put 1 HS81 on each side to run 2 ailerons each and it they had no problems. In fact both planes flew with a lot more "crispness" due to the increased servo speed.

I agree with AJC. If it is larger than an .020 then I go to a HS81s. The HS55s are great throttle servos though.


I had an ACE Simple Ultimate with the exact setup you are going to use. I ended up switching to an OS .25 because it could swing a larger prop and revved lower than the Norvel .15. The HS81 on the elevator stripped in flight and I almost lost the plane. I switched to an HS205 on the elevator and it was fine after that. I flew it for 4 years and now a friends son has it.