Author Topic: PSS-JET T1000 (Read 22240 times)

IceWind · « **on:** January 14, 2008, 22:32:16 PM »

Hi,

Just posting some photos of my PSS-JET T1000.
I have a bunch of boring constrution photos, but i won't post them here.

Just one or two to let know the model. It's from a german guy that sells models in EPP.

http://www.epp-modelle.de/

joe · « **Reply #1 on:** January 15, 2008, 09:05:04 AM »

Looks nice Ice.
What size is it? Depron tail?

IceWind · « **Reply #2 on:** January 15, 2008, 10:22:39 AM »

Thank's joe.

It as 1100mm span.
Actually the original tail was on depron, but someone adviced me to change it, and i really didnt like it also. So i used instead 3mm coroplast.
But when you buy the kit it comes with a depron tail.

Using the coroplast made it bit tail heavy, but even using some weight on it to correct the CG point its still under the specified weight, that is 450gr.
Also instead of gluing the wing, i made a detachable system for it, using 3 plastic nylon screws. Can be noticed on the top of the wing.
It has ailerons and elevator.

cvanscho · « **Reply #3 on:** January 15, 2008, 20:03:13 PM »

Hi Ice

Thanks for the photos! Nice to see something that is different (to us here)!

Give us a report as to how she flies!

Chris

IceWind · « **Reply #4 on:** January 16, 2008, 05:35:34 AM »

Well, i havent flyed it yet!
And i left it back at home :-( but at is seems the places around seem more for this type of planes than for parkflyers and so on. I'll probably bring it over here and maiden it here. It just needs a paiting, and some fiber-tape to re-enforce some areas.

IceWind · « **Reply #5 on:** October 28, 2008, 12:08:59 PM »

Ok, it's done and it was maddened.

It's not perfect, but at least it fly.
I was using 20gr lead plus 2 AA batteries and even moving it a bit further to the back it was dropping the nose.
In the manual (that now i can read, it was only available in German before) they say to balance it at 110mm from the LE backwards. And indeed making it balance on that point it has a bit too much weight in the front.

Brian · « **Reply #6 on:** November 04, 2008, 20:39:37 PM »

Hi Ice,
Using your photo ,which has your near wing half pretty much in plan view, I calculate the CG at 140mm-145mm.

Brian

IceWind · « **Reply #7 on:** November 04, 2008, 22:46:44 PM »

Hi Brian,

Out of curiosity what values did you used to calculate the CG point?
As i also obtain a different value from the one said on the manual.

Brian · « **Reply #8 on:** November 05, 2008, 12:39:56 PM »

Hi Ice,
I normally fly F3A.
CG has an element of personal preference.
I always end up at 32% of Mean Average Cord (MAC).
For slope slightly forward helps penetration, so go for 30% MAC.
That figure I gave is a guestemate from photo.
That wing is tapered so MAC is half way out a wing panel.
Measure 30% from LE at half span each wing panel and join the two points through the centre to get the point at the root.

Brian

Fred · « **Reply #9 on:** November 05, 2008, 14:03:37 PM »

Hi there,

Might help everyone, but here is how to find the Center of Gravity using the geometric method...
You can find loads of excel spreadsheets on the internet to find your CG aswell !

First job, is to find the MAC, then you position the CG at whatever % you want (I usually go between 25 to 33% depending of the profile, machine type and so on...) on the MAC.
Draw a line from that point to the root (perpendicular to the root), and that is your CG line.
Basically, you can do the CG of your plane anywhere on this line.

Fred

IceWind · « **Reply #10 on:** November 05, 2008, 14:51:26 PM »

Hi Brian,

Thanks for the details, i just wanted to see what method/values you were using.
To try and figure how the T1000 designer comes up with the 110mm value, as from the calculations i made and i was using 33% i didn't get that value.

Fred, thanks for the excellent graphical explanation.
When it comes to online CG calculators i usually use this one:
http://www.blueskyrc.com/cg/index.php

But there are many more.

For the next fly I'm going to keep along those lines using 30% to 33% and see how it fly.

Also the T1000 is made of EPP and what i noticed is that the body bends easily, could this make any influence while flying?
Because if it bends during flight the angle between the tail and the main wing is going to be different.
Not used to these full EPP planes so not sure if this can be a problem.

Thanks.

Fred · « **Reply #11 on:** November 05, 2008, 15:16:07 PM »

Hi Fernando,

Well, if the tail keep moving up and down, that will definitively change the way the glider is flying. (incidence change).

Might worth to put a carbon tube underneath the fuselage :?:

By the way, talking about the CG, the CG depend also of the tail incidence. Change the tail incidence, you will need to change the CG, and that's something lots of people forget when looking for the perfect CG (alright, on a sport model, you will barely see the difference anyway !), and of course, of the profile used (for the cg range).

IceWind · « **Reply #12 on:** November 05, 2008, 15:47:26 PM »

Hi Fred,

When i noticed that behavior i thought in that, insert a CF tube along the fuse to prevent it. It's also tricky to identify the tail incidence because of this.

Fred · « **Reply #13 on:** November 05, 2008, 15:54:43 PM »

I have an incidencemeter... I can bring it to check the next time we fly together.
But no worries, I'm sure the bottom of the fuselage is flat ? Keep it flat when you put the tube, and that should be enough.

IceWind · « **Reply #14 on:** November 05, 2008, 17:24:13 PM »

Thanks for the help Fred.

To help things out the bottom of the fuse is not straight, i wish i had photos to put here to show I'll try and get some.

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Author Topic: PSS-JET T1000 (Read 22240 times)

cvanscho