merlin3

My Feedback: (4)

bfree I just sold my saito 180 for the same reason and bought a ys 140.

Maudib

My Feedback: (51)

My only suggestion before trying anything esle is switching back to regulr size fuel line... I've actually heard that larger line hurts you more than helps.... Yes with larger line you can PASS more more fuel theoretically... but it takes more pressure to push it through there (more fuel, more weight/drag)... Better to run smaller line to push smaller amounts faster than larger amounts slower. Nose down/level it doesn't need to pull as much... nose up it has to pull the fuel against gravity.

Worth a try anyways...

bfreee

Maudib, thats the same thing I told my buddy who's helping me beat my head. There is larger column of fuel to lift with the larger tubing. The reason Im using the large fuel line is because I was having this same problem when level with the small tubing. So going back to the small tubing will only cause more trouble, unless I try using it for some of the length, maybe just the clunk & stopper tubing. Can anybody recommend a certain type of pump? I have read the whole Saito info section on pumps. Does anybody have first hand experience with the saito or perry's pumps? Does Saito have a tech line? Thanks for the ideas guys

bfreee

emvin, have you had a chance to try it hovering?, Have someone hold it vertical for you & see what happens. I've had 3 dead sticks now due to this in 5 flights. If I never put the nose up straight I would have never known

akschu

My Feedback: (5)

<disclaimer>
Let me first say that I have never used a pump on a glow engine (everything I have is 72 and smaller) but I'm not a stranger to carbs, fuel, or presure due to some of my other hobbies. This means the following is theory and isn't backed by actual experience:
</disclaimer>

The idea of using exhaust presure to push any real amount of fuel doesn't sound like a great idea. First, the exhaust pressure would vary depending on tuning of the engine and air presure. Second, whatever fuel delievery system you use must be able to deliever more than enough fuel at all states the fuel system might be in. On a model airplane this means that the fuel system must be able to deliever more fuel then what the engine needs regardless of attitude and temperature. If a fuel system is not able to do that, then the needle valve is no longer the bottleneck (read regulator), the bottleneck becomes the fuel system trying to keep up.

That said, unless the tank gets enough pressure from the exhaust to push the fuel though whatever system you have, at whatever angles your airplane might be at, you will never get it to work. For this reason I believe that a pump would be worthwhile. While the requirements of the fuel system are still changing, the pump is always able to feed the system with enough fuel making the needle the bottleneck. This explains why many that add pumps find that they run at 1 turn out instead of 3 or even 4.

A good test of my theroy would be to open the needle and see how far open it can get before the engine floods and dies. If you can't get it rich enough to flood, or if your 4 turns out before it will flood then that would tell me that the current fuel system is not able to supply enough fuel to make the needle valve the regulator in the system.

Hopefully that helps, or even makes sense. I would also be interested in hearing feedback from others on the forum more versed in glow engines. My knowledge comes from theory and playing with my 180HP snowmobile.

Later,
schu

randy racer

My Feedback: (3)

with the fuel tank as far back as needed on this plane you may be able to make it run but not as good as it can. the perry pump system i have used on 2 planes so far has been great. the engine runs solid from full tank to empty, long hovers and up lines never fade. the pump cost around 30.00 bucks and i will use it on every thing i build of this size with a glow engines from now on.

randy racer

EMVIN

bfreee, Yes I have hovered as well as full throttle up lines with no adverse affect....I will be sure to try holding the plane straight up to see what happens......It is possible the engine was leaning out and I just didn't know it.....I already have the Perry VP-30 installed its just bypassed......The VP-30 was suggested to me by the guys at the Club Saito thread (RC Universe) .....If you have any saito questions they can answer them.....

bfreee

To all, thanks for the help guys, found out some very interesting things. A friend of mine works at a plant where they have a meter that will read pressure, vacuum, ect. down to 1/100th of a psi. He brought that home & we hooked it to the pressure line from the muffler to the tank with a Tee. We found that we got no pressure at all until we went wide open & then it was .02 psi. We knew we had a problem right away. Got the cowl off for the 20th time & started looking carefully. We found two things wrong. One was the pressure nipple in the muffler had worked loose. It still was in place fully, it just would turn if your twisted the hose, Secondly, we found a small cut in the pressure line right at the pressure nipple. Very small & undetectable until you pulled on the hose. We replaced the lines, re-loctited the pressure nipple & ran it again. We found that the engine made NO pressure at all at an idle. This would explain why it is so important to have the tank 5mm or less lower than the spray bar per the manual. If you have the tank any lower, the engine would not be able to draw the fuel to the carb. This is a fact. The engine does actually suck the fuel to the carb at speeds lower than approx 3-4 thousand rpm. As we sped the engine up, the pressure increased smoothly to .5psi maximum at full throttle. This will lift the fuel easily more than a foot. The system actually works very well as I guess every happy running engine knows by exhaust pressure. As the rpm's increase, so does the fuel pressure, which is exactly what the engine needs. No need for the pump. I would go as far as to say that the fact that a pump applies a steady even pressure through the whole rpm range is not how these carbs are really set up in these engines. Its obvious that the two needles give you lattitude hear, but as in any engine more fuel is required at higher rpm. This because you do not have the extra pull coming from the vacuum applied to the spray bar that you have at idle & part throttle. This vacuum helps draw fuel in. When you open the throttle above part throttle, the vacuum is lost, therefore an increase in pressure is needed. This is the same principle that is at work with a fuel pressure regulator on a modern fuel injected car that I work on everyday. In a car, vacuum is applied to the nozzle of any fuel injector that is below the throttle plates (read in the manifold), this low pressure area makes it easier for the fuel pump to spray its fuel into the manifold, therefore they use a regulator to decrease the fuel pressure when high vacuum is present. When the vacuum disappears (read wide open throttle) more pressure is needed to achieve the same fuel delivery. There are other factors at work here, but this is the basic premise. In the end, my problem was all created by me, and the fact that when you only have a half a psi of pressure, you cannot afford to lose any of it. Always check your pressure lines any time you have a lean/stalling problem. Be very careful handling silicone tubing, it loves to split!!!!!!!!!!! I hope this helps someone. Basically, the only thing I found out is that I had everything setup right from the begining & just had some small leaks that weren't apparent. Thanks again to everyone that helped me. I stuck it out & finally found the problem like BobPhx said, it would be worth it when I figured it out. In the end it was the simple things!! Thanks again. Bruce Freeman

Russmall

Everyone, I just wanted to give a flight report after putting three flights on my new Yak this morning. My set-up is as follows... YS 160 DZ on a Gator Softmount with an NMP inline muffler. Prop is an APC 18x8W. I'm amazed at how quiet this combination is. Servos are Hitec 5945's on ailerons and rudder, with 5925's on the elevators. The battery pack is an 2400 mah Li-ion with a Smartfly regulator. The all-up weight is 11lbs, 4 oz........The flight performance of this airplane is just fantastic. Very easy to hover and torque roll at about 1/4 throttle. Harriers are a piece of cake and it does some of the prettiest flat spins you've ever seen. I even got it to climb a little while doing an inverted flat spin (a first for me). Knife edge is perfectly straight with no coupling issues at all.......Anyway, if I sound excited about this airplane, I AM!!! I had the 72"version with this same engine and it flew great also, but I think this new version flies even better........RS

wingburner

My Feedback: (17)

Will a Saito 125 fly this plane well enough for IMAC....Doesn't need to do 3-D.

I think it could come in under 10 lbs....Only problem would be balance...

Will have the plane tonight and can look it over.

R/C Foolish

My Feedback: (6)

Good Luck,

I am still waiting if anyone has flown this with a G-26.

bfreee

Hi all,
Watch the landing gear, they will not take a hard hit, I'm thinking of putting my funtana 90 gear on the plane. The aluminum bends & takes the shock out of hard landings. Of course if I could land like someone who can fly that would help. Was running cg on the tail side which makes it hard to get the nose down for landings. Ripped the landing gear out, which came back & tore up the right horizontal stab & punched a hole in the bottom. Bummer. Plane was flying awesome though. Harriers could be done blind folded with no wing rock at all or very little. Very stable. Off to the repair shop

bfreee

Since no one else is answering you, I'll give my 2 cents, I still don't know what IMAC involves, but if it doesn't require a hover a 125 ought to fly it well. I have a 125 in a funtana 90 & it flys real well. I hope this helps.

mr.bigal

My Feedback: (-1)

Emvin you said you hoverd it i have a os 160 how well do you think it will hover

Wildstyle

You would most likely want to use a single elevator servo with a ply/carbon joiner for the elevator halves.
I have no idea of the weight of the Saito 125 but if C.G was to be a real problem you could place the elevator servo up the front and use a push rod, The only problem I could see is making two slots in the fuse for the rods that connect to the elevators. just a thought.
Anthony.

EMVIN

MRBIGAL, I'm using a Saito 180 with a Pro zinger 18X6, Morgan cool power 30% and the plane weighs in at 11lb 12oz.....It hovers at a little more than an idle....As for the OS 160 I have never owned one so I dont have any experience with it.....I do know that you should try to achieve the high end of rpm's within your engine's allowed limit and use ths largest diamiter with a lesser pitch prop...It took some experimenting with prop size as well as an ample break in of the engine to achieve maximum results....Good Luck..........EMVIN.........

randy racer

My Feedback: (3)

the 72" houvers at 1/2 throttle with a 160 OS with lots of pull out using a Bisson pitts style muffler and Perry Pump on 10% nitro. mine weights just under 11 lbs so the 73" should do as well. also i only used 1 elevator servo as Wildstyle said. i have tried alot of props and the best on this setup for me is the Menz 18-6, it will spin up fast and pull hard. the xoir 18-6 worked good but didn't spool as fast but is a good prop.
i'm still trying to figure out what engine to use on my 73". i want to go gas and like the 3W 28cc but i am afraid that the wing loading will be to heavy.the 26cc engines i'm afraid won't have the power i want. if any of you guys have the all up weight of your 73" yak please share them with me and include engine and servo set ups.

thanks

randy racer

EMVIN

Not much going on here lately......Any new stories??? I have been flying the #%** out of mine and having a great time. Right now its in for repair....Had a pretty hard dead stick landing. broke the firewall clean off, trashed the landing gear, cracked the canopy and cowl.....Well,, all the woodwork is done and the engine is mounted once again.. I'm just waiting for the new plastic to get here....EMVIN....

gm4213

Hinges. Am I really to believe that those aileron's and elevators are hinged with only 2 hinges? My kit came with 2 precut hinge points, hinges pre-installed. My kit also included a set of hinges in each hardware bag. I was planning on adding 2 additional hinges to the aileron's for a total of 4 on each side and 1 for the elevators and rudder for a total of 3. Any thoughts?
Thanks

EMVIN

gm4213, there are 3 per elevator half, 6 per wing and three on the rudder.......The slots are there. They are under the covering...If you feel along carefully you will find them....

TedG

Anybody - with a YS 140 upfront. What prop are you using. I've tried the 17x4w and it seems to small, but with the 18x6w its slow to spool up. Any suggestions.

yarom

My Feedback: (82)

Just for reference, the YS 1.20 NC uses 16x8 on this plane (YS 20/20 fuel). The YS 1.40DZ uses 18x8 on this plane (30% heli mix for fuel). Both spool right and fly great. I suspect the regular YS 1.40 might be OK with 17x6 or 17x8 if there are such sizes to be found.

BTW, once you get to these prop dimensions, look around for Bolly and Mejzlik props. They offer sizes and build quality APC doesn't.

EMVIN

Try a 17X6

SUKJOON

Hi. all!
I have finished maiden flight yesterday.

Zenoah 26cc engine.
16x10 meizlik 8300rpm
Jr8611A for rudder, two 8611A for elevator. two 8411 for aileron and 507 for thottle.
1,400mA nicd reciever battery (installed end of fuselage)
Total weight : 12lbs

She flies awesome!
Perpect rolling harrier perfomance but little nose heavy and I have to switch 18x6 for more trust.

EMVIN

At the field