T-Rex 500 Info

[Angelos]

Trev,
assuming someone uses the overweight 4200mAh pack; what do you suggest... leave the heli untrimmed on the pitch axis or put a bit of back trim to compensate for it?

-Angelos

[trvo]

Personnally, I keep the swashplate at 90 degrees to the mainshaft, I never use trim on cyclics because if you set it up right it'll hover straight on the first flight (providing the CoG is correct), I also never trim on windy days as everytime you enter a different direction / orientation of flying it'll change. If the pilot feels the need to trim it then I'd do it in a pirouette in calm weather until the 'wobble' that the off-centre CoG creates is eliminated and it just sits there nicely, it will cause problems in the inverted orientation however.

So, in direct answer to your question, a bit of back trim is fine for upright, but as soon as it goes inverted you will be assisting the offset CoG instead of combatting it, so no trimming for me.

Trev

[Angelos]

This is what I was hoping you'd say. If you trim it back it gets twice as bad when you are inverted and and will also twist the heli on when you are on the side. Still however, from what I have seen the CoG is significantly off to ignore. Not many pilot would be willing to put up with the drift.

-Angelos

[trvo]

It's just in front of the mainshaft by about 1cm, not significant at all, people are talking about very fine amounts here.

Trev

[raptorheli2]

trev, it is way more than 1cm on my 500, go hold your heli on the flybar and you'll see what i mean. nose is quite a bit down.

cheers

[trvo]

It's deffo not more than 1cm in front of the mainshaft, I have a full sized tail servo so prolly helps balance it out...

Trev

[Angelos]

Trev,
I didn't measure where exactly the CoG is but holding the heli from the blade grips it tilts a good 10-15 degrees forward. This is more than I am willing to tolerate and other pilots that saw it think the same too. I personally can't stand the constant drift, perhaps you are used to is.

-Angelos

[raptorheli2]

here is a piccy of the 4200 setup on my own heli for reference, to me thats more than a small amount.

[trvo]

Mine is nowhere near that much, I wouldn't tolerate that much either! I've checked mine the same way you checked yours. Mine hovers stationary hands off in calm weather with no drift and the swash at 90 degrees to the main shaft...

As I say, it's quite possibly the tail servo that balances it out, everything else except the rx is under the mainshaft...

I'll get a photo tonight if I can find someone to hold it for me...

Trev

[raptorheli2]

well i am extremely puzzled to say the least, this has exactly the same stuff on it as yours. also my dc up is under the rx tray helping the situation, i don't believe a tail servo will make that much of a difference to mine but i have a 9254 here so i will put it on for reference and get more pics. the 720 is also heavier compared to the 760 but it must only be by about 10g, again, i'm confused here. unless your using the metal plate also?, thats probably 30g plus now.

i will get pics with the 2200, 2500 for comparison if i can convince the mrs again..lol

cheers

[trvo]

well i am extremely puzzled to say the least, this has exactly the same stuff on it as yours. also my dc up is under the rx tray helping the situation, i don't believe a tail servo will make that much of a difference to mine but i have a 9254 here so i will put it on for reference and get more pics. the 720 is also heavier compared to the 720 but it must only be by about 10g, again, i'm confused here.

Me too, I could be getting confused with the 2200's but I will check again tonight, I checked the balance since I only put the cells in as a joke and was supprised. It is a metal cased JR 8900 servo and about 1cm from the boom clamp. Weighs in at 59g...

EDIT: 9254 is 48g...

Trev

[trvo]

Just checked and it's spot on, will get a photo of both packs...

Trev

[trvo]

Here ya go, both the 2200's and 4200's. You can see that the 2200's are rather tail heavy and the 4200's are spot on. That'll explain why I think it flies better with them. That tail servo must be heavier than it looks!

Trev

[Tim Procter]

At least you could smile Trevor..

[trvo]

nah, pi$$ed off, been at work all day

Trev