Cessna at Full Throttle?

[elty19]

I've heard that to setup a sport plane, one of the tests is that if you have it on full throttle.... it should fly straight - i.e. not climb. For a cessna... should it be the same? Don't think so but experts... please comment!

thanks!

[Mazon]

A plane shld be set up so that it flies straight and level across the throttle range, from low throttle to high throttle, the plane shld not ballon or sink.There are several factors that can affect. e.g. motor thrust angle, C.G, wings aligment, incident angle.

if your plane is climbing at full throttle, try lowing ur motor thrust angle

[Airborne]

For any plane, it shouldn't climb at full throttle, that is my opinion..

[Tony]

Assuming that your plane is already trimmed for level flight, if your plane climbs on high throttle, increase your down thrust - a little bit at a time until you are able to get the speed increase without the attendant climb.

[gowest]

next you should check the amount of negative elevator when you roll over for inverted flight. With good CG setup, inverted flight only required just a little notch of negative elevator (down elevator) to hold level during inverted with the same airspeed of upright. Ideally with a perfect CG / thrust, you shouldn't even have to hold down elevator during inverted but that's way too much to ask

[Tony]

As your plane is likely to have an assymetrical airfoil or even a flat bottomed airfoil, inverted flight will require more down input to maintain inverted level flight. This is normal.

[joe yap]

For any plane, it shouldn't climb at full throttle, that is my opinion..

In ideal situation, yes. In practical, no. How much of it will depend in individual design. As speed increases, the lift generated by the wings will increase and if the pitch attitude is not reduced, the plane will climb.

That's why planes have pitch trim controls. Some planes trim by the cable system. Some uses trim tabs. Big jetliners uses horizontal stabilizer to trim.

[elty19]

thanks!

thanks guys! sounds like if this were a sport plane with symmetrical 'wings' it is more likely to fly level at full throttle, but for a cessna.... would I be right to say that I should expect it to climb a little then? sounds like given the input above... this would on balance be correcT?

[Tony]

Its a balance. With the right amount of down thrust, you would still get a bit of a climb when at full throttle but nothing to objectionable. Transiting to a cruising speed, you should get level flight and on idle it should have a nice flat glide. It sounds more difficult to do than it actually is. We used to trim free flight planes that had small diesel engines (Mills, DC etc) or rubber bands for power that flew without RC. Same adjustments to down trust, CG and trims (we just bent the balsa wood) at the appriopriate places to get the plane to fly as desired.

[joe yap]

The issue of symmetrical wing or flat bottomed wing, in fact, has little to do with this. The other contributing factor to this is that high wing planes has the drag line high above the thrust line. This also creates a marked pitch up moment with the application of throttle.

[aeronautical]

if you see the cessnas at seletar airport, they have the same effect. in fact, planes are designed to fly S&L at power settings ranging from 65-80% of full throttle which would be the cruise power setting. and climb naturally with full power. its just the way it is. so if you wanna fly fast at full power and at S&L, put some down ele to maintain S&L.