LSP972

My Feedback: (13)

N struts or no?

Upper ailerons or no?

Of course, the N struts are pretty much mandatory if one fits the upper ailerons. So I guess my question is, do the upper ailerons REALLY make that much of a difference?

I have no problem fitting separate aileron servos; done that before on an Ultimate kit. But I'm thinking that the lower-ailerons-only set-up, using one servo, will be considerably lighter than the extra servo, woodwork, N struts, etc. necessary for four ailerons.

So, you guys that have flown both configurations; did the top ailerons add enough performance increase to justify the extra weight? I'll be using a 91 Surpass, so I won't have a surplus of power. And I fly rather casually; loops, rolls, snaps, spins. None of this flip-flop around/make-the-plane-emulate-a-helicopter stuff.

Your thoughts appreciated...

Campy

My Feedback: (1)

Why not use connecting linkage from the lower wing ailerons to the upper wing ailerons ?

blvdbuzzard

Mr. Mr. Campbell, on the ones I have built, I went with the long swept back wings. On the first one I went with just ailerons on the bottom wing and threaded rod with snap on ball links for the struts. I got real tired of putting all of those links on each time I took it to the field. It flew pretty well with just the ailerons on the bottom wing.

On the second one I built I had a dog issue with the wings. My dogs chewed up the wings and I had to build new ones so I just cut some foam core balsa sheeted ones. I went with ailerons on both wings and a standard servo on each side of the lower wing driving the top and bottom ailerons. I used a cut down control horn mounted back wards on the trailing edge of each aileron and a ball link and threaded rod between to join the top to the bottom. For the struts, I made them look like the ones on a Pitts. I mounted the struts with 4 small screws to ply mounts embedded in the wing. Set up time was about 5 minutes with the Pitts style struts. The flight control was improved with 4 ailerons. When at real low air speeds I did not notice a drop in response to inputs. With the two servo aileron setup I was able to mix in some differential which helped with adverse yaw at low speeds. The snaps and spins were tighter also. It needed just a touch of aileron in knife edge.

I flew both with K&B .65's, so I was not over powering them. I do not think they need to be hover bats.

Hope this helps.


Dru.

LSP972

My Feedback: (13)

Thanks, Dru. That's kind of what I figured; the two extra ailerons do improve things, but not that much overall. You mentioned adverse yaw; can you amplify? We're talking necessary use of the rudder at low speeds, right?

Campy, that would be the way I'd do it; drive the upper aileron via a pushrod from the lower one; one servo driving two ailerons; just as Dru described. The trouble with that is, you have to add quite a bit of structure in the lower wing to accomodate the servo on each side; not to mention the extra weight, drag, etc., of the pushrod link. And driving four ailerons with one servo is a BAD idea, for several reasons.

Dru, I had one of these some years back. It had the short swept wings and four ailerons, and would just fit in the back of my truck, so I had no assembly/disassembly issues. I've still got that truck, and I'm not sure that the longer swept wing version I'm building will fit back there assembled. One of the reasons I don't fly my Ultimate more than I do is the hassle of set-up and tear-down when I take it out.

My first Aeromaster had a YS 120N; power wasn't an issue. The reason I'm not doing this one exactly the same is because of the lesser engine; I'll probably need all of that extra wing area. And if I have to take the wings off to transport, I'll be right back where I started from. The lack of interplane struts will ease that pain a bit.

I dunno; I'm still on the fence about this. On the one hand, I'm big into convenience these days. On the other hand, this is a very intensive kit to build, with a ton of work involved, and I worry about sacrificing some flight quality for the sake of making my life easier.[&o]

blvdbuzzard

The yaw problem I had was at lower speeds. I would input aileron for a right turn, but the left wing would drop as if to make a left turn then it would swing around to the right. When you got used to it, it did not scare you. When I setup some differential, it stopped and was not a problem.

What I did not like about the building of this plane is the scarf joints. To get them right takes time and a lot of effort. That is one reason I cut foam cores for mine.


Dru.

Rodney

I built and flew seven of the old Lou Andrews Airomasters. I tried all the wing configurations and prefered the swept back upper, straight lower as it was easier to balance without adding nose weight. I never tried ailerons on the upper wing so can't comment on that. All mine were powered with Fox 60's and were quite agile. To combat the yaw, I always used differential ailerons, lots more up than down as that was easy to mechanically set up way back then. That was may favorite bipe of all time. I just recently picked up the Giant Aeromaster kit and have it nearly complete, have a Quadra 72CC on it, hope to try it out before the year is out.

Ed_Moorman

My Feedback: (1)

I have owned a couple of configurations and the best flying one I have flown is with both wings swept.

With ailerons on the bottom only, you need a lot of aileron throw to get what you would expect from a monoplane. I remember having to go back a couple of times and increase throw so I would recomment 4 ailerons on any biplane.

You need in the 10%-12% of the wing area for ailerons. For your combined wing area, this makes for a fairly large aileron on a single wing. If you don't have this, you need extra throw, which gives you adverse yaw. In addition, rolling from the bottom wing only tends to produce a slight barrel effect on the rolls. Rolls are more axial with 4 ailerons. Personally, I like 4 servos with the wires running up the cabanes. These take less work, less adjustment and give good response.

MajorTomski

HMMM interesting thread

I built one a long while back with two short swept wings, standard N struts, and four ailerons. Two servos in the lower wings drove the lower ailerons, a wire link from them drove the uppers. Kept the airplane assembled and transported it in one piece in my Windstar. Never had a problem with adverse yaw. Rolled like it was on rails.

T

LSP972

My Feedback: (13)

All good food for thought; thanks, guys.

Okay, I'm with the need for differential if I go with the stock ailerons. But how do you do it at the servo on this sort of linkage? I could try to find some offset bellcranks, but it would be easier to do it at the servo.

Sitting here thinking about it, I just don't see how. The simple method for strip ailerons certainly won't work...[sm=drowning.gif]

blvdbuzzard

When I did the two aileron servos I used the Tx to do it. I used slot 2 and slot 6 of the Rx. I set it so I had only about 40% down aileron. It was a 6 channel Rx and I was only gonig to use 4 channels so I had two extra. I ended up putting in a smoke system later. It added to much weight but looked cool.


Dru.

LSP972

My Feedback: (13)

Yeah, with two servos it would be a no-brainer with the 9Z.

What I'm trying to figure out is how to do it mechanically with the stock one servo set-up. At one time, many moons ago, I had that book by Jim Newman that shows a bunch of different mechanical control linkages and what they do. Sure could use it right about now...

I was sketching it out last night, and think I see how to do it. I'll build a "test rig" using an actual servo and see how it works.

blvdbuzzard

Way back when, I had a FGPK4. It was a 4 channel Futaba that had sevo reversing only. I needed differential on a mid wing slope soarer. I ended up using a spring loaded linkage and a aluminum bloack to stop the torque rods from moving. The torque rod would hit the block and stop, the spring loaded linkage would not bind the servo. I know it would not work on the Aeromaster, but there is always a way.

Dru.

RCVFR

My Feedback: (7)

Ed, on the "both" swept wing you liked, was it 48" or 52" span?

Thanks.

tukkus

My Feedback: (2)

Does anyone have the prints for the Aeromaster.....I have one with swept wings and the bottom wing snapped in two on a bad landing....it's a fairly clean break but it's hard to say if it will come out straight..so if i can't get it straight i'd like to build a new wing for it...i bought this off of someone in my club....mine also has one servo controlling the ailerons but im going to change that so i can get more throw from it..and if i can get the plans maybe i'll do top and bottom ailerons