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Feb 28, 2013, 09:40 AM
Row 0, Seat A
G550Ted's Avatar
Quote:
Originally Posted by dz1sfb
Ted,
The KFm2 adds a noticable amount of improvement in lift and gentler stall characteristics over the flat plate wing. Of course there are even better performing airfoils, but the KFm2 is quite simple to build, and adds more stiffness.

I realize the flat wing on this model will suffice, but I have had so much fun with this airfoil on aileron equipped models that I just totally sold on its merits over the flat airfoil for planes of 30" ws and up. I like and prefer the flat wing for smaller models and 3D types.

Marcel has done an awesome job here, and I don't want to infer that somehow it is less than it is as it is. Just add my twist on it for my build that I believe will be value added.

Ken
Thanx Ken.

I have no experience with the KFm2 and appreciate your input. I did once build a KFm3 polyhedral wing for a trainer type in addition to an undercambered wing and an Armin wing for test purposes. I liked the KFm3 best for that application but had no comparison with a flat plate. I may use a KFm2 on my Mermaid build.

Ted
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Mar 02, 2013, 02:32 PM
Row 0, Seat A
G550Ted's Avatar

Thrust Line


Marcel,

I've been meaning to ask about the thrust line you chose for the high mounted motor/prop. Have you experienced any noticeable pitch down tendencies with high power? What are your thoughts on setting the motor cant for a down angle like (but I'm sure not near) that on your Drongo design?

IIRC you don't have a convenient place to fly off water but can we expect some flight vids soon (even if off grass)?

Thanx,

Ted
Mar 02, 2013, 09:42 PM
Registered User
justj's Avatar

Mermaid Build


I got my Mermaid kit in the noon mail today. Hoosier Cutout Service mailed it on Thursday. Outstanding and unique packaging BoP! Everything arrived intact and I got right to work! Cut the parts from the sheet and started gluing! The trial fit of the parts was excellent, I only had to sand out my poor cuts of the retaining tabs.Hope I have enough pics for everyone! So far everything is great!
Mar 02, 2013, 11:26 PM
Registered User
mintie's Avatar
Neat little plane....dont see any reference to AUW....can someone enlighten on this .... cheers mintie
Mar 03, 2013, 04:33 AM
boerie roll
vleisie's Avatar
Quote:
Originally Posted by G550Ted
Marcel,

I've been meaning to ask about the thrust line you chose for the high mounted motor/prop. Have you experienced any noticeable pitch down tendencies with high power? What are your thoughts on setting the motor cant for a down angle like (but I'm sure not near) that on your Drongo design?

IIRC you don't have a convenient place to fly off water but can we expect some flight vids soon (even if off grass)?

Thanx,

Ted
The thrust angle for the Mermaid is set-up differently compared to my other models because the motor is mounted much further forward. The angle is chosen so that the prop wash pushes down on the tailplane. An increase in thrust increases the downward push, lifts the nose and balances out the pitch down moment. My model has no noticeable pitch down tendencies.

I'm hoping to get some video during this week, unfortunately it takes a lot of organization.

Quote:
Originally Posted by mintie
Neat little plane....dont see any reference to AUW....can someone enlighten on this .... cheers mintie
AUW for mine is 560g.

All the best, Marcel.
Mar 03, 2013, 06:49 AM
Row 0, Seat A
G550Ted's Avatar
Quote:
Originally Posted by vleisie
The thrust angle for the Mermaid is set-up differently compared to my other models because the motor is mounted much further forward. The angle is chosen so that the prop wash pushes down on the tailplane. An increase in thrust increases the downward push, lifts the nose and balances out the pitch down moment. My model has no noticeable pitch down tendencies.

I'm hoping to get some video during this week, unfortunately it takes a lot of organization.



AUW for mine is 560g.

All the best, Marcel.
Marcel,

Thanx for the quick response, and glad to hear your Mermaid doesn't suffer adverse pitching with power like many other designs. (Another sign of your great work)

560g is remarkably light with a 2200 mAh battery. Not knowing exactly where that battery is placed, do you think it possible for lighter (smaller) batteries to also be used and still maintain CG?

Waiting patiently for your video like a toddler waits for Santa on Christmas eve.

Ted
Mar 03, 2013, 10:19 AM
Retired CAD guy
birdofplay's Avatar
19-20 oz sounds about right to me.

But as I was cutting it It just "felt" like I was looking at a larger plane.

Two more going out tomorrow ! :-) Thanks folks !

Bob
Hoosier Cutout Service.
NEW DOMAIN name ! http://www.hoosiercutoutservice.com/
Mar 03, 2013, 10:41 AM
Vladimir
tkach's Avatar
You now have a very beautiful model! I want to do this to yourself!
I have a question: your model plane wing?
In one photograph, I saw profile ..., ribs?
Please describe the manufacturing wing detail.
Sincerely, Vladimir.
P.S.
Specify the center of gravity and position of the battery.
Thank you! Vladimir.
Last edited by tkach; Mar 03, 2013 at 10:53 AM.
Mar 03, 2013, 01:20 PM
Retired CAD guy
birdofplay's Avatar
The Original form Marcel is a simple FLAT FOAM wing.

Ken is doing a KF wing - probably a 40% layer on top of the original wing.

Then on the previous page someone is doing a ribbed Foam built up wing.

Bob
Hoosier Cutout Service
Mar 03, 2013, 02:13 PM
Ken's CAD Models
dz1sfb's Avatar
Quote:
Originally Posted by birdofplay
...

Ken is doing a KF wing - probably a 40% layer on top of the original wing.
...

Bob
Hoosier Cutout Service
Actually 50% precisely.

Ken
Latest blog entry: Mini H Quad Project
Mar 03, 2013, 02:55 PM
Retired CAD guy
birdofplay's Avatar
Thanx Ken.
I didnt read that closely.

Has 50% become a better # than 40% ?
mI thought simple KF on top was 40% with ~ 1/4 rise at the back , last time I looked .

Hey Ken ya goin to Toledo ? ( silly question )
I'll get there around noon Friday.
Tony Pacos that night and leave early PM Sat.
Mar 03, 2013, 04:59 PM
Ken's CAD Models
dz1sfb's Avatar
Quote:
Originally Posted by birdofplay
Thanx Ken.
I didnt read that closely.

Has 50% become a better # than 40% ?
mI thought simple KF on top was 40% with ~ 1/4 rise at the back , last time I looked .

Hey Ken ya goin to Toledo ? ( silly question )
I'll get there around noon Friday.
Tony Pacos that night and leave early PM Sat.
Will be at Toledo Friday and Sunday in the swap area.

Had lunch at Tony Pacos last year.

Ken
Latest blog entry: Mini H Quad Project
Mar 03, 2013, 07:47 PM
Retired CAD guy
birdofplay's Avatar
Lunch ?

Ya gotta go for the Dixieland band and Friday night.

I'm talkin about the OLD Paco's not one of the new ones.

OK I'll check the swap area on Friday then
Mar 03, 2013, 10:53 PM
What could possibly go wrong?
nickchud's Avatar
Quote:
Has 50% become a better # than 40% ?
mI thought simple KF on top was 40% with ~ 1/4 rise at the back , last time I looked .
Yup!
Here's the KFM thread
Mar 03, 2013, 11:30 PM
boerie roll
vleisie's Avatar
Quote:
Originally Posted by G550Ted
Marcel,

Thanx for the quick response, and glad to hear your Mermaid doesn't suffer adverse pitching with power like many other designs. (Another sign of your great work)

560g is remarkably light with a 2200 mAh battery. Not knowing exactly where that battery is placed, do you think it possible for lighter (smaller) batteries to also be used and still maintain CG?

Waiting patiently for your video like a toddler waits for Santa on Christmas eve.

Ted
The battery sits quite far forward. If you bend the front end of the battery deck down to the bottom of the nose during the build to make more space in the nose for the battery to move forward, you should be able use something lighter than the 2200mah, but probably not less than a 1800mah or so.

I got some video yesterday, will edit and upload sometime this week.

Quote:
Originally Posted by tkach
You now have a very beautiful model! I want to do this to yourself!
I have a question: your model plane wing?
In one photograph, I saw profile ..., ribs?
Please describe the manufacturing wing detail.
Sincerely, Vladimir.
P.S.
Specify the center of gravity and position of the battery.
Thank you! Vladimir.
The wing is not built up, it is flat depron with a carbon spar. The CG is on the spar. The battery position is near the front of the nose.

All the best, Marcel


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