radial1951

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Hi Jim, Hobbsy is very close with that fuel consumption figure, and on the safe side when you include taxiing, landing, slow touch-n-goes etc.

My FA200R3 is in a 68" Su31 which came with a 12oz(350cc) tank for a 30c gasser. My first 1/2 dozen or so flights I set the timer at 5min to be safe, and came down with about a 1/4 of a tank left. Say 9oz / 5min / 2ci = 0.9 oz / min / cubic inch. That's about 10% on the safe side !


With some part throttle flying there's more like 1/3 of a tank remaining, which is about 0.8oz / min / cubic inch. (Radials sound great on a light throttle flypast). I am about to fit a Dubro S-24oz(700cc) tank which should be plenty for an easy 12min flight.

I find standard silicon tube works fine. They don't need a big fuel flow rate as the cylinders are only about 65 size, hence the smallish carburettor with standard fuel nipple. I don't know anyone who uses a filter.

Regards, RossG
radial1951
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fly boy 2

My Feedback: (1)

The photos received gave me an idea.  I am not sure what it is called but I will give it a go.

 

Would I damage anything by cutting a narrow slit in the wood on the left side connecting the firewall to the fuselage?

mike early

Any of you boys like the 115 better than the 125?

AeroFinn

Hello Jim

Thanks for your reply. What you say sounds good. Just a follow up question: What do you mean by "..You may have another issue to deal with.." ?

Artto

w8ye

My Feedback: (16)

He's talking about you having your low speed mixture needle set too lean with the resulting failure of the engine to immediately achieve minimum idle speed and the poor acceleration from minimum idle speed.

The Saito 125 glow engine normally is not able to sustain a idle speed below 2100 rpm.

The original Saito muffler for the Saito 125 is the same muffler casting used on all the larger Saito singles. Therefore it is rather large.

With the Turbo muffler, the Saito 125, it does not make more top RPM than the original Saito muffler but is more compact and takes up less room and will fit your plane better.

With the smaller Saito engines ( for example 56, 82, 91, & 100), the Turbo muffler will give you as much as 300 rpm on top end when using the correct prop for the engine.

SrTelemaster150

What about the FA150 & FA180? Do they pick up as much RPM W/the Turboheader Muffler?

AeroFinn

Thanks w8ye, the acceleration from idle speed to max speed is perfect now; however I tried to richen the LS needle just a little bit to help the engine to immediately achieve the minimum idle speed. The result was, unfortunately, that while the transition from max speed to idle speed went good the engine couldn't idle reliably below 2400-2500rpm. So this makes me think the problem might be related to lack of back pressure due to large flex pipe without a muffler.

RC Specialties

Thanks Jim,

I could not have said it better.

Jim

RC Specialties

SrT,

Yes, they do achieve better performance. This is true for all models but the 1.25.

Jim

w8ye

My Feedback: (16)

2500 rpm is about the minimum reliable speed that I've been able to achieve with the Saito 125 and I have 5 of them.

earlwb

They put in a pretty hot cam and valve timing on the engine, so it can't idle all that low. The more hot the cams are the less able the engine is to idle well.

jimbrock

My Feedback: (1)

Thanks, Ross. I guess my 32 oz tank will be fine. The fuel tubing was a concern, but thanks to you I won't worry about it. Now to get the dang thing installed. Next would be installing the glow driver. A lot of wiring and plumbing involved in this PT 17. And figuring how to access the stuff after it is covered (planked) up.

The life of a builder!!!

AeroFinn

ok. Well, I guess I'll try to Turbo Header and then tune the carb. Hopefully I can achieve 2000 rpm idle with good transition from both idle speed to max rpm and vice versa. If not, then timhee to try some other engine, maybe. I wonder if the FG-20 idles lower. I dislike high rpm idle because landing becomes challenging. The engine is in a Seagull Zlin Z-50 and last time I tried a 15 X 8 prop I hardly got the model slow done for landing. So I went to 16 X 6 and this combe seemed to be easier in landings. Or then I lack skills to do the final approach correctly..maybe I should practise slowing down with nose angled more, I don't know.. EDIT: I might experiment with a 2 3/4" spinner, too. I'm using a spinner nut at the moment. The aluminium spinner might help with the idle.

mike early

My new 56 turns an 11x9 prop at over 10500 running rich. Ordered some 11x10 and 11x11 props. More powerful than I expected. Only 2 tanks through it so far...

blw

My Feedback: (3)

The 56 will turn an APC 12x6 pretty good too. This is one of those engines that I'll always want to have around.

spaceworm

Sounds like you pretty much answered your own question by going to a lower pitch prop. Perhaps a wide blade prop would help also. An on-board glow driver might keep the fires lit to permit a lower idle, or an electronic ignition system with spark plug and glow fuel would give you lower idle plus better fuel economy.

Good luck..

Richard/Club Saito#635/FA-100, FA-120 abc, FA-130T, FA-180

triumphman49

My Feedback: (149)

Hey AeroFinn,

My vote would be for the electronic ignition as Spaceworm suggest . . . lower idle and fuel economy. C H Ignition or RcExl both good choices, while Adrian @ C H may be able to offer adjustable magnet ring - great guy.

T-man49
Club Saito 723

Hobbsy

My Feedback: (102)

Richard, while I'm still limited to 5 lbs with the left arm I've been working on some planes in various stages of construction. I have an ACE 4-40 ready to cover I changed my mind about the engine choice. I'm going to put a .40a on it and the central mounting of the throttle arm is problematic. here's my solution which I believe can be transferred directly to the plane. I'll move the engine mounting rails and all. The mounting rails are now bolted to the PSP adapter plate so I could better fugure this out.
Picture #1 is throttle closed/engine shut off
Picture #2 is mid travel
Picture #3 is full throttle
Picture #4 is engine set up

warbird addict

Thanks for that, a buddy of mine just got back to me on this as well he had a manual for the 150 and it said lsn to be set flush with the face of the throttle arm to start with but this will be very rich and may be turned in up to 1.5 turns as needed for response and transition.
I just needed a start point is all, I got this used so I wasn't quite sure where the start point was with the lsn ,the hsn was way too rich and now knowing the start point on the lsn it was too lean by about 3 turns, with owning so many different engines I'm now of the practice of writing the carb baseline needle settings on a piece of paper and laminating it somewhere inside the cockpit with epoxy.

radial1951

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Hi Joel, A lot of ARFs are set up for 2 stroke engines. Dubro actually make a linkage kit which puts the throttle in the right spot for most standard 4 stroke setups.

I scratched my head when trying to set up the throttle linkage on my Tiger 60 with OS FSα-81 (sorry). I used a Paddle Pop stick (that's Ozzie for Popsicle stick) as a template to get an idea if it would work. The setup worked ok so I thought "why not?" and hardened the wood with CA and it's been there ever since!

BUT, because of the geometry of the pivot point and push rods, there was almost no throttle movement in the first 1/2 of the servo travel and everything in the second 1/2. SPEKTRUM to the rescue! My new DX8 has Throttle Curve adjustment, so I could accelerate servo travel in the first 1/2 of stick movement and slow it down for the rest. Works like a charm...

Regards RossG
radial1951
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lopflyers

My Feedback: (12)

A Popsicle stick!!![X(]

radial1951

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Thanks! I use them all the time for reinforcing repairs :-( , making lightweight mounts for batteries, receivers, fuel tanks, servo mounts in foamies etc. Much stronger than balsa and you can CA laminate 2 or 3 for super strength. Just a drop of CA in any threaded holes after you put the screw in and take it out. Makes the thread much less likely to strip.

Now... AQUESTION: Do you guys who mix your own fuel use "proper" synthetic oil (Coolpower etc) supposedly designed for model engines? OR would any 2 stroke oil be just as good? Are they just the same with a different label? TIA.

Regards, RossG
radial1951
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SrTelemaster150

As far as which EI system, my vote goes for the C&H system for the ease of timing adjustment due to the infinately adjustable trigger magnet ring.

I'm converting ALL of my Saitos to EI, even my FA91, although that is getting down to the point of space concerns in an appropriate airframe for that size engine. It's eventually going into a World Models 1/5 J-3 Cub so there will be plenty of room & the module/battery pack will help balance CG.

IMO, any 4-stroke from 1.20 up will definatley benefit from EI. The fuel savings will soon pay for the initial cost & the reduced fuel load required could make up for the added weight. When an on board glow is being considered for these larger engines, EI is a much better option. Below .91 it's not that much benefit in the smaller airframes & not all that practical.


Another trick for lower dependable idle it to employ a heavier nylon prop. The added weight brings a flywheel affect to play.

lopflyers

My Feedback: (12)

Mixing fuel? Nah. I'm too lazy for that and at least at my LHS they have all kinds of already mixed fuels at decent prices.

Hobbsy

My Feedback: (102)

WildCat guy here too.