BaldEagel

Hi all

I have just got a Jamara Swallow 90 ARTF as a starter plane to get into patten flying, anyone any suggestions on this craft do I have to beef anything up or have I bought the wrong plane.

Kolsso12

Jamara Swallow 90 is a good start in to patten. It fly great with YS 110 and OS 120 4-stroke.

Rendegade

It's a good airplane, I built mine many years ago and form what I know it's still flying.

Mind you I did a fair few mods to it.

first thing I'd do is get rid of that crud f/glass landing gear and either go for dural or carbon, that thing it s just an accident waiting to happen.

Also, make an effort to build the plane straight, if you don't have one already, get an icidence meter, and get everything 0-0. they're notorious for being out of alignment.

and finally, throw out most of the hardware and do it properly from the start, you'll thank your lucky stars you did. a good pull pull setup on the rudder helps with that big flapping thing at the back!

majortom-RCU

My Feedback: (40)

Mine flew beautifully on a YS110. 'Effortless' was what my caller said about its flight behavior. I had a couple hard landings with CG too far aft at first, and one of those cracked the fuse at the usual spot, just aft of the wing TE, the weak spot on lots of ARFs. I stripped the fuse covering, glassed the fuselage sides from wing saddle most of the way to the tail, recovered, moved the CG forward a bit and everything was fine after that. I procured a replacement, but haven't put it together yet.

SwampFlier-RCU

Beef up the thinest part of the fuselage (beneath the fron of the canopy) it's a weak point
Make a search for Swallow 90, there are a couple of build threads here on rcu (probably 2 years old)

BaldEagel

Thanks for the info guys its good to know this is not the lemon I thought it was, looking at the contents of the hardware etc: I have a full set of Graupner horns and 3mm carbon push rods reserved for this bird, I also always attach my UC with nylon bolts so they give way before the fus. I will post when I'v flown the thing.

BTW have any of you guys done or thought about putting two elevator servo's in the tail?

Mike

majortom-RCU

My Feedback: (40)

With the YS110 up front I used pull/pull on the rudder, and dual elevator pushrods with elevator servo also in the radio compartment. I set mine up for 12Ëš elevator deflections and CG towards the rearmost of all the recommendations I saw in the builder threads. It turned out to be very touchy on landings until I moved the CG forward about a half inch and turned the elevators down to +/- 9Ëš, with plenty of expo on top of that. It certainly doesn't need elevator servo power, and it doesn't need weight in the tail.

BaldEagel

I was not thinking of weight in the tail just that awfull double pushrod arrangement, servo's in the tail would make for a much more direct connection and more precise control, and probably less overall weight with two small servo's if power in the tail is not required. If that is not possible I will have to put in two or one servo's in the cockpit area and close loop link the tail. The British Model Flying Association (BMFA) almost requires two servo's for the elevator control it certainly recommends it anyway. So perhaps one servo with a closed loop linkage to the elevators will be the way to go what do you all think?

I do not understand your movement measurement? it cannot be 12" or 9" can it

Mike

majortom-RCU

My Feedback: (40)

The 12 & 9 were degrees of deflection in the elevators.

I will beg off the rest of your question, since I like the dual pushrods/single servo, and try to avoid driving one elevator with the other. Two mini-servos, if that's what you have in mind, might work, but I would be concerned about the servo gear strength, even though the rated torque would probably be adequate.

BaldEagel

Degress I understand now.

I plan to use some Votz Mini Star servo's I have to hand they are designed for big glider wings for flaps and ailerons, they have metal gears, speed and torque all in a small package, I think this will work.

Mike

BaldEagel

Here's one I did earlier, this is in a Yak that also had the split elevator push rod, I decided to try ailivators and this was how I did it.

Mike

majortom-RCU

My Feedback: (40)

Very interesting, and a pull/pull variation I've never seen before. Maybe I'll give that a try on one of my models.

BaldEagel

majortom

The ailivators are tremendous fun full roll controll right down to the stall, they are on a very snappy Yak but by switching out ailerons and putting in ailivators it seems to control the snap somewhat, which is strange to a certain extent as its the pitch stability that causes the snap due to excessive elevator mostly so you would thing that moving the elevators differentially would make it worse not better. Any thoughts?

Mike

majortom-RCU

My Feedback: (40)

I'm afraid that's beyond my experience, so I'm not sure what to advise. All I can say is I fly mostly aerobatic routines, IMAC & pattern, and I address any unintended snapping tendency as soon as it arises, which is seldom now that I've learned how to avoid it. I avoid it by keeping my elevator throws to the minimum necessary to do my aerobatics, usually something around 10Ëš deflections; by taking steps to lighten any kit-built or ARF model; and by moving CG forward if necessary. I also do static lateral balance to eliminate any rolling tendency at low speed.

I do fly 3D for fun, and there of course snapping is part of the game. I have never done a delta or flying wing or any other variation of ailevators, so my understanding of this approach is shallow at best.

BaldEagel

majortom

The snapping tendancy of the Yak is not a fault its a traint of the airframe due to the extreme taper of the wing, this is what makes it so airobatic, it will snap if you apply elevator to quickly but if you feed in the elevator in a controled maner you get a true responce, the short moment arm of the Yak will make it change pitch very quickly which stalls the wing and it will snap right every time, so smooth is the answer which is fine unless you are in a panic at the time. Makes for an interesting variation from all those stable Extra's and Cap's HO HO.

MIke

majortom-RCU

My Feedback: (40)

I'm somewhat behind the times in relation to the Yaks. I see them all over the place, but I have a hangar full of the more familiar aerobats, and I don't want to be acquiring more planes until I crash the ones I have. This is what happens when you get old. But thanks for helping me think straight.

BaldEagel

majortom

I am a silver surfer too so don't put yourself down about being behind the times, I'm up to date because I have to replace my aircraft often for the obvious reasons, I tend to push the envelope a lot and go to the field at least 3 times a week, compared to some guys in my club I get a years flying in one month comparitivly, besides the swallow I am also building an 85" QQ Yak this will have a 45 or 58cc MVVS in it, just hope it last longer than some of my other's maybe I will take it easy with this one.

Mike

BaldEagel

In the instructions the front wing joint is a plywood plate, but the accesories provided are two alloy dowels, also in the plywood accesory bag are the two pictured mini servo plates also pictured I am going to install these at the rear of the fus for the elevator as per my previous post, I am sure they are provided for such just not in any updated manual, I am going to use two Hitec 5245MG mini servos for the elevator, I know this is overkill but you can't be too carefull on the pitch servo's in my opinion.

I will post pic's of the mods needed as I progress the build.

Mike

BaldEagel

majortom

If you would be so kind to answer the following I would be much obliged.

side and down thrust in degrees or washer thickness under mount and engine lug?

your final c of g location?

Thanks in antisipation.

MIke

majortom-RCU

My Feedback: (40)

I looked at my old notes on CG. The Swallow product I had came with recommendation for CG at 125 mm aft of wing LE. Everyone's comments on RCU were for much further aft than that, back as far as 180 mm. I set mine up originally at 170 mm and found that too touchy on landing. I ended up moving forward to about 160 mm and was very happy with how it handled there--nice landings, no porpoising, pitch sensitivity just right.

The whole drift of my experience over the last few years has been to keep weight out of the tail, knowing that an ounce of tailweight will need 3-4 oz of noseweight to balance it. By that formulation, an ounce saved in the tail means 4 oz saved in the model. Only exceptions have been where I had an engine heavier than the plane was designed for. I still have a couple planes where I had to hatch the battery somewhere into the tail structure, so I know if I did one of those again it would pay to put one or two servos in the tail.

Reading my old notes brought back more vividly what a sweet plane the Swallow is when properly set up.

(foregoing posted before I saw Baldeagle's latest)

Engne thrust offsets: I saw one note from a guy who said he needed 2Ëš right and 2Ëš vertical (don't remember whether he said up or down), but I used no vertical offset and my plane was pitch-steady with punching or chopping throttle. I did not use any side offset adjustment in the engine mount, but did work in some throttle-to-rudder mix in the trimming phase, and eventually got that just about perfect. Unfortunately those settings have been erased from my TX. I think I used a fairly high throttle threshold (maybe 80% or so--well above straight & level cruise setting) before it kicked in, and I just fiddled with it until I could pull straight up at wide open throttle and go up with no apparent yaw one way or the other.

BaldEagel

majortom

Now thats what I call a decent answer thank you, I also read the c of g mods that most people ended up with and I must admit I have been working towards 160mm as you have suggested, I am not advanced enough to know if I will have to compensate for the rear servo's at this time but I am thinking of moving the rudder and throttle servo to a position in front of the cockpit as there is a lot of room therem this may offset any weight distrubution I will have to do, once I get the plane substantially finished (this afternoon hopefully) I will put it on the c of g jig and hang the servo's in certain positions to rough check the c of g , then just keep moving them around until I find the best compromise.

Once again thanks for the information in your last post it will prove most helpfull.

MIke

SwampFlier-RCU

I set mine at 170mm from the leading edge and right thrust for the engine abou 2º (I guess) I put a couple of washers on the right hand (view from front) side of a dubro soft mount.
Mine has an Irvine .72 witha a custom header and a tuned pipe flying a 14X6 prop
It's about to be re-maidend after a mishap that put it out of comission for a while

BaldEagel

What do you guys thinik of attaching the U/C with Nylon bolts? I have done this on various other planes with great success in the past, as instead of the mount ripping out on a bad landing the bolts shear and leave the U/C behind, I fly from a very rough grass field and inevitably you get at the least a nose over on nearly every landing due to the grass length and the end of the landing run.

Everything is now attached, I have used better equipment for the horns and things, just need the mini servo's to be delivered so I can estimate the positioning of the internals so that I can establish the C of G.

BTW I am putting a Jen 91 with a Genisis throttle pipe on this so it will not lack power thats for sure.
Hoping to get it finished by the week end so I can fly it then.

I am going to fibreglass the inside of the tank bay as I can see daylight through the bulkhead joint and while I am at it I will reinforce the landing gear attachment point. This is the latest incarnation of the Swallow and has fibreglass reinforcement under the cockpit area all the way back to the standard position for the servo's. Time to go I'v been working on this all day and she indoors who must be obayed is getting restless.

Tommorow is another building day.

Mike

BaldEagel

Well she is finnished, I have installed the elevator servo's in the tail and moved the rudder servo into the cockpit area, this compensated for the digital mini servos well and I have achived a 160mm CofG without any ballast and a lightweight plastic spinner, Hope to fly this afternoon will report my findings tomorrow.

Unable to upload photo's at the moment something wrong with RCU. Will try again tomorrow.

Mike

d_bodary

My Feedback: (85)

The swallow version with the fiberglass reinforcement means you have a wing that is not fully sheeted and the fuselage is pretty well lightened also. I have both versions and never weighed them. But the second version is quite a bit lighter. I used a mark bellcrank on the second one for the elevator. due to being able to install it easily with the lightening holes already. I set my CG at 165mm. And using a YS 91 and the 110 i used a 16 oz. hayes tank on one and a tetra on the other one. I moved them both back as far as i could to minimize the cg shift of burned fuel.

As far as the stock fiberglass gear goes i tend to like it. I did break one on a dead stick off field landing and replaced it with a bolly std. F3A gear. it was quite a bit shorter than stock and looks a little funny. On the landing gear plate i used some carbon fiber cloth on the inside and the wrapped some fiberglass around the outside andput it about 3/4 of an inch on the fuselage. which makes it plenty strong. The plate comes out fairly easy as long as you decide to do it before it's broken in half. As far as the aluminum dowels go in the front of the wing. I was concerned about the glue not sticking well to the aluminum and replaced them with wood dowels. probably not needed but i was more comfortable that way.

The wheel pants supplied are thin and for a glass runway i could'nt get them to last so i used Bolly pants. Used a Sullivan tailwheel assembly. Along with a mini servo for the throttle. Did'nt trust the supplied pull pull cable so i used Du-bro 4-40 pull pull cables. And used Radio South pro hinges.

They are a nice flying plane so I felt the added cost and effort was worth it.

Dennis