Rc plane flying poorly in some weather.

shedweller

Hi all.
As the title suggests, this is about the weather affecting flying performance.
I have a diamond 1100 glider and it is reasonably powered but is certainly no rocket.
Tried flying today, being a calm day and all, but i could barely get it to climb. There was a slight breeze and as i turn around to go downwind i could really see it sitting tail heavy and generally lumbering along. But it did pick up speed so as i turn around to climb again into the headwind it just would not climb well at all. I flew in the same place a few days ago with a strong headwind and although it didnt make much headway into the wind, it climbed really well and allowed me to get really high for some gliding.
So does air pressure and humidity affect flyability? Are there certain pressure/humidity levels that aren't conducive to flying well?

Bruthal

If properly powered, it should climb in any conditions.

When there is a headwind, climb rate can seem better as the glider makes less headway relative to the ground than on a calm day, and so it climbs higher in less forward distance.

shedweller

Thanks for the reply. I went again yesterday evening and just after launch it threw a prop blade. I cut the power quickly enough and landed ok. One blade snapped off at the root so I wonder if the prop blade was bending forward under power and this was reducing thrust? Hmm...
A new one has been ordered so i'll know more when that arrives.

Bruthal

If there is enough power to bend blades forward, there would be more than enough for strong climb. Most powered gliders have folding props which can flop forward when at rest, but they don't get "bent" or hinged forward in flight because of centrifugal force.

Holding the glider in hand and motor on full will show if there is good power.

shedweller

Bruthal wrote: »

If there is enough power to bend blades forward, there would be more than enough for strong climb. Most powered gliders have folding props which can flop forward when at rest, but they don't get "bent" or hinged forward in flight because of centrifugal force.

Holding the glider in hand and motor on full will show if there is good power.

Ah, i left out that small but important detail. Does my wifes head in when i do that!
It is indeed a folding prop. I was wondering though, if the prop blade was failing during that earlier flight and lead to poor pulling power. I'll never know now but i'll be watching for this kind of thing in future!

Bruthal

shedweller wrote: »

Ah, i left out that small but important detail. Does my wifes head in when i do that!
It is indeed a folding prop. I was wondering though, if the prop blade was failing during that earlier flight and lead to poor pulling power. I'll never know now but i'll be watching for this kind of thing in future!

The prop blade will either be intact, or broke, there is not really an in between in terms of its shape. It can be cracked alright, but it will still keep its shape until it completely breaks.

It might be remotely possible the whole prop holder slips on its shaft, and so is not keeping up with the motor revs. But id imagine that would quickly show up as a loose prop holder on the shaft.

shedweller

Just a little follow up. New prop arrived, made by apc propellers. Flew just now and wow what a prop. What was once an underpowered dog of a yoke is now a rocket. Climbs at half throttle and full throttle is scary! Esc and battery were only lukewarm upon landing so i am a happy pilot now.

Bruthal

Definitely must have been something up with other one. Wrong size, out of balance, or loose.

shedweller

Bruthal wrote: »

Definitely must have been something up with other one. Wrong size, out of balance, or loose.

Yeah i am curious about it alright. It was tight and balanced. The size is in question though. It said 7.5x4 but so did the new one, despite being slightly shorter blades. The yoke they are meant to go on is longer so that explains the shorter blades.
It was certainly a learning experience!