Dear All,

I've been building Phoenix's Giles 202 http://www.rcuniverse.com/magazine/a...article_id=334 but I have a problem with the CG.
It is supposed to be between 95 an 105mm, but my Giles is way WAY tail heavy [:@] (around 3 cm behind 105 mm).

I haven't done anything that would add so much weight to the tail, so this must be a design issue? Any idea how to fix it? Or is it possible that I measured the CG from the wrong staring point?

BTW: I've tried to add 1cm of plywood between the firewall and the engine mount, but the result is almost the same (my manual doesn't say anything about 12cm between the firewall and the prop hub, but I found that info in other posts).

Thx for any help!

J

Use this thread to find the information you need on the Phoenix Giles 202. I can't remember what the distance from the FW to the prop hub is, but it's in there (4.75" or something like that).

[link=http://www.rcuniverse.com/forum/m_1424468/anchors_1424468/mpage_1/key_Phoenix%252CGiles%252C202/anchor/tm.htm#1424468]RCU Phoenix Giles thread[/link]

Note: HINGE GAP YOUR AILERONS BEFORE YOUR FIRST FLIGHT. I had incredibly bad flutter at half throttle and haven't flown since (crashed). Good looking plane so I'll get it going again.

Good luck.

I've read the article but couldn't find any info on fixing the CG.

More info: the engine is MVVS .45, weighting around 400g (14 oz).

With experimenting I found out that I'd need 300g (10.5 oz) weight in the nose to balance the plane. [&:][&:]

Found this in the Giles thread that Stik-n-Rudder had in his post

Well yes, I know it's supposed to be between 95 - 105 mm (which is between 3.75 to 4.13 inches). But in order to
achieve that CG, I would (or will) have to put 300g (10.5 oz) weight into the nose.

I spoke to the retailer today and he said "well, if total weight falls inside the specification boundaries, that's OK". That might be true, but I'd like to avoid adding extra weight.
Sadly, that seems to be the only solution [&o]

Rgs
Jernej

Just for the record:

I did the following modifications to the plane:
- cut out the pilot (and painted the canopy black)
- added 1cm plywood to position the engine further from the firewall
- reinforced the "weak spot" with 110g fiberglass and epoxy (under the canopy)

The CG is now just where it has to be :-) The plane has flown once to date. It is slightly underpowered with MVVS .45 (needs long concrete runway), but I can't really say until I do some more flights.

Pictures can be found here: http://forum.modelarji.com/viewtopic...r=asc&start=20 (don't mind the language)

Rgs
Jernej

Very nice jernejk. The pilot looks like he's got terminal neck cancer anyways. The canopy looks great painted. I used the plywood trick to move the engine out too. Mind providing more detail on how you glassed the "weak" area?

Thanks