Help trimming plane - RCCanada - Canada Radio Controlled Hobby Forum
RCCanada - Canada's Radio Control Hobby Forum
General RC Aircraft Discussion Discuss anything RC related

Closed Thread
Thread Tools Display Modes
Old 09-19-2007, 11:09 AM   #1
RCC Senior Contributor
I am: Marc B
Join Date: Jul 2004
Location: Sk.

Feedback: 1 / 100%
Posts: 691
Total Props: 0
Help trimming plane

       Remove this ad - become a site supporter!
Hi everyone,

I've been flying for a while, but have always just mixed all bad tendencies out. Got the EF Yak 88" flying all summer, but am discovering some tendencies that I want to run past some of you.

Inverted is neutral at 2/3 throttle.

Elevators are carrying alot of up trim to make it fly straight when Upright. So now it ballons when power is cut. Is a bit pitchy otherwise, but not seriously bad. Already shimmed engine UP with a washer.

Plane is still only slightly tail heavy, but everything is already jammed up front, but this is fine for me as I do mostly 3D.

Couples badly to gear in KE, both directions, with proverse roll too.

Significant wing rock in upright harrier. Minimal inverted.

Is this normal tendencies? I realize planes have to be worked on for 100's of flights, but these seems excessive to me.... I bought this plane as the cream of the crop after a year of research and did not think it would exhibit much of this at all. What's the point spending a $900 on a plane when I can get a knock off to do the same thing.

And maybe the problem is my setup or am I expecting too much?

Where does the problem lie. Where do I start tweaking....engine thrust, stab incidence, mix coupling, or just add fuel and ignite with match!!

BigBreeze is offline   Quick reply to this message.

Sponsored Links - Subscribe to remove this ad.
Old 09-19-2007, 11:26 AM   #2
RCC Supreme Contributor
JimMcIntyre's Avatar
I am: Jim McIntyre
Join Date: Aug 2002
Location: Claremont Ontario
Radio of choice:
# of RCs: 999

Feedback: 1 / 100%
Posts: 4,345
Total Props: 1

I'd check for excessive washout.
MAAC# 12719
Si fractum non sit, noli id reficere - (If it ain't broke, don't fix it).
JimMcIntyre is offline   Quick reply to this message.
Old 09-19-2007, 08:03 PM   #3
RCC Supreme Contributor
hillmanr2's Avatar
Join Date: May 2005
Location: Kelowna, B.C.

Feedback: 0 / 0%
Posts: 2,435
Total Props: 0
You will ALWAYS get some degree of rudder coupling with any plane. Par for the course. As you well know your engine thrust is off. You say you are tail heavy but is this based on flying experience or "the range" given. On an upwind 45 degree up line you should be able to roll inverted and maintain the track. Most arfs have a overly nose heavy range. You must get your CG done first before any further mixing or thrust angles. Please read the attached article by Peter Goldsmith well. There are others but I think this one is the most clear.
Attached Files
File Type: pdf pgoldsmith_20on_20trimming_556.pdf (56.2 KB, 67 views)
Imac # 4751
Speedway and Hobby
PTA Hobbies
hillmanr2 is offline   Quick reply to this message.
Old 09-19-2007, 08:39 PM   #4
I am: Boolean21
Join Date: Sep 2002
Location: Singapore

Feedback: 0 / 0%
Posts: 38,228
Total Props: 56
There are many ways to skin a cat, but I would say you are way too tailheavy. I would move the CG forward, then bring up the wing incidence to get rid of the elevator trim and unload the stab a bit. You should find that your thrust line is then is much closer, and your mixing starts to go away.
PurgatorY is offline   Quick reply to this message.
Old 09-19-2007, 09:10 PM   #5
Dennis 9412
Level 3 Supporter
★ Site Supporter ★
Dennis 9412's Avatar
I am: Dennis DuBois
Join Date: Dec 2002
Location: Washago, Ontario
Radio of choice:
Airtronics SD-10G, JR XP9303
# of RCs: 10

Feedback: 14 / 100%
Posts: 1,689
Total Props: 4

Hi Breeze:

You mentioned that you have a fair bit of up elevator to fly level.

I had the same problem with a Wild Hare Edge 540, and found that the r/h stab had a 2 degree positive incidence. I ovalled the hole in the fuse for the positioning tab on the stab to bring it back to 0 degrees, and it fixed the problem. I seem to have read somewhere that this was a problem with the EF Yak as well.

Check out the stab incidence, you might be surprised.

Dennis DuBois
MAAC 9412L
IMAC 3821
CFI Orillia Aeromodelers
Dennis 9412 is offline   Quick reply to this message.
Old 09-20-2007, 06:24 AM   #6
Ed Smith

Feedback: / %
Posts: n/a
Total Props: 0
I am surprised that none of these posts suggest that you go back to basics.

Start again. Put the ready to fly airplane on the work bench. A flat and level one we would hope.

Check the following.

Engine wing and tail incidence.

Engine side thrust if any, relative to the wing.

Alignment of wing to the fuselage. Alignment of tail to the wing.

Do the wing tips have the same incidence? (See Jims post)

Is the dihedral even tip to tip. Is the tail even with the dihedral?

Is the fin vertical and true with the fuselage centre line?

Is the balance point in the correct place?

Is the centre of the fuel tank aligned with the balance point?

Before I even think of attempting to fly a 170mph Pylon Racer the above is mandatory.

Ed S
  Quick reply to this message.
Closed Thread

Quick Reply

Register Now

In order to be able to post messages on the RCCanada - Canada Radio Controlled Hobby Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

Member names may only be composed of alpha-numeric characters. (A-Z and 0-9)

!!ATTENTION ADVERTISERS!! If you intend on advertising anything on this forum, whatsoever, you are required to first contact us here . Additionally, we do NOT allow BUSINESS NAMES unless you are an Authorized Vendor. If you own a business, and want to do sales on this site via posting or private message, you will need to follow the rules. Shops, Stores, Distributors, Group Buys without being authorized will see your account terminated.
User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Your Name
Your first name and last initial is required if you plan on using the forum.
Which city & province you live in. This is mandatory for classified listings.
Radio of choice?
Which radio is your current favorite to use?
Number of RC Vehicles?
How many boats, cars, planes do you own?


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
vBulletin Message

Thread Tools
Display Modes

Forum Jump

All times are GMT -5. The time now is 12:15 PM.

vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.