Hey Guys, I'm not sure if anything is wrong or what but when I do a radio check on the ground the throttle response is quick but when I'm flying around there's a noticeable delay in throttle response. It seems all the other servo movements are quick enough but the throttle is just slower. I do have a Saito 62 on her with a new JR servo that isn't the same as the others but suppose to be a higher quality servo then the previous one. I can move the stick full up and the engine won't react right away....about 1 second or 2 later. I know that doesn't sound like a lot of time but it is when your in a fix. Remember the response time on the ground is quick just in the air it's slow....might be the engine too? The radio is a JR Quattro.

This might not be a problem with the RX or servo.

Your engine is leaning out a bit in the air, so you may get a good response when the plane is sitting on the ground, but in the air, it is hesitating as it runs up.

You will perceive this as a slow throttle response.

Your best bet is to tune the engine with the tank purposely low, then check the tuning by pointing the plane nose high and running the throttle up and down.

This puts the plane in a "worst case" condition.

Get it set up properly for worst case, and it should run better most of the other time.

In addition to the "leaning in the air" noted above there is another factor that has nothing to do with the engine at all.

Sound travels at 600 fps +/-. If you're 300 ft away that's a half second delay before you hear the difference whan you make a throttle change; 600 ft away = 1 second delay, etc. It can be quite noticable.

You may want to try a different prop. I have seen that with a smaller dia. prop or a smalle pitch it would respond faster.

Jon

A very good point!

Add that to the normal servo response, and the plane might seem to be "lagging" a bit.

Thanks guys! I'll do the worst case check and tune and see what happens. Never thought about sound delay but that sure makes since.

If you head out to the Wicita Air Museum Friday night we will have the WRCC club meeting and there will be some brains you could pick to help you out.

Hogflyer

There's going to be a little bit of delay from when you open the throttle until you hear the response. Part of it is what Charlie said above, the sound getting back to you. But another part of it is the simple fact of the fuel flowing into the engine. It will take a small bit of time for the fuel to flow from the carb up through the intake manifold through the valves into the cylinder. I image what you are hearing is perfectly normal, but you just arent' used to it. Like Hogflyer said, take it out and let them listen to it. If there is anything wrong they'll hear it, but I image it's just fine.

Ken

That's one of the advantages of four srokes. You can see the puff of smoke when you hit the throttle. That puff indicates right away that you have throttled up, even if it is a couple seconds before the sound gets to you. Cloudy days are a problem though as it is hard to see the smoke.

Don