HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Jan 27, 2013, 06:30 PM
Dr John
pmpjohn's Avatar
Lake Placid, Florida
Joined Dec 2001
2,712 Posts
Quote:
Originally Posted by nightlightrepair View Post
Working on this little GWS project and, by my best-guess calculations, I'm going to need a 10 X 6 Pusher Prop for EP. I was surprised to not be able to find one anywhere in this size. APC makes a sport pusher in that size, but it's not EP. They do make a 9 x 6 pusher for EP, but no 10s. I decided to go with a wooden zinger 10 x 6 pusher, and I figure it will be plenty light enough. Do you guys have a preference on pusher props (brands, wooden vs. composite)?
No need for a pusher. Use a regular prop, numbers forward and reverse the motor rotation.

Dr John
pmpjohn is offline Find More Posts by pmpjohn
Reply With Quote
Sign up now
to remove ads between posts
Old Jan 27, 2013, 07:22 PM
Registered User
Joined Jun 2005
2,439 Posts
robusp, I am happy that your model flew without damage. Success is thrilling. I hope you can now go forward with variations and improvements. Congratulations.

Charles
canard addict is offline Find More Posts by canard addict
Reply With Quote
Old Jan 27, 2013, 07:24 PM
Lighting Up the Darkness
United States, GA, Loganville
Joined Jan 2013
23 Posts
Thank you Dr John. I'll do that!
nightlightrepair is offline Find More Posts by nightlightrepair
Reply With Quote
Old Jan 27, 2013, 07:41 PM
Dr John
pmpjohn's Avatar
Lake Placid, Florida
Joined Dec 2001
2,712 Posts
You are welcome
pmpjohn is offline Find More Posts by pmpjohn
Reply With Quote
Old Jan 28, 2013, 01:16 AM
Registered User
Tick Point's Avatar
Joined Mar 2008
511 Posts
Here's the first three launches.
On you tube;
Shinden Maiden at Tick Point (4 min 53 sec)

or look for Shinden Maiden at Tick Point
flights on video;
1. look at :55 seconds and 1:40 What kind of stall do you see? Looks like a shotgun blasted it sideways. Wind was right to left, not straight in.
2. camera was removed to move cg forward, (too far forward)
3. see the slight pourposing after launch (just above the bushes)? Are those many little pitch stalls in the canard? It flies!

There were some spectacular mid flight stalls (yaw stalls, I think), I definitely have to keep her moving.
Tick Point is offline Find More Posts by Tick Point
Last edited by Tick Point; Feb 02, 2013 at 09:01 PM.
Reply With Quote
Old Jan 28, 2013, 01:34 AM
Registered User
perttime's Avatar
Tampere, Finland
Joined Nov 2004
4,177 Posts
Quote:
Originally Posted by Tick Point View Post
Here's the first three launches.
Where was the CG when you got it to stay in the air?
perttime is offline Find More Posts by perttime
Reply With Quote
Old Jan 28, 2013, 03:36 AM
Registered User
John235's Avatar
Sydney, Australia
Joined Mar 2006
1,315 Posts
Hi TP, Good to see you having some fun on the slope!

Those 2 nose up stalls look like a main wing stall, probably due in part to rearward COG. It looks like you know what you are doing with COG adjustments, so I guess small adjustments from now on. I reckon the fins on your Shinden look a bit too small. It seems to be stable at high speed, but when slowing down it will probably start to rock side to side due to inadequate yaw stability (due to small fins). I think landing is always going to be tricky but adding larger fins would probably help the low speed stability and make it a bit more predictable.
John235 is offline Find More Posts by John235
Reply With Quote
Old Jan 28, 2013, 04:21 AM
What could possibly go wrong?
nickchud's Avatar
Market Harborough
Joined Apr 2006
3,616 Posts
Success for TP and Rob - Wahoo!

Both those planes look a handful, more so Rob's. If you give those pushers an extra degree of positive incidence, you might find you can reduce the tendency to climb with the throttle. On the other hand, it looks quite fast enough to me. I hope your eyes are better than mine!

Slope soarers really do have some beautiful places to go. I wouldn't have dared to put my camera on the plane before chucking it off the cliff for the first time! Brave man.

I'm sure John's right about the fins.



Nick

PS Where's Tick point? Looks like CA, but too cold.
nickchud is offline Find More Posts by nickchud
Reply With Quote
Old Jan 28, 2013, 07:41 AM
Takeoff=Option Landing=Must
robusp's Avatar
USA, NY, Depew
Joined Jan 2009
782 Posts
Nick,
Would you call this positive incidence:

Rob
robusp is online now Find More Posts by robusp
RCG Plus Member
Latest blog entry: Pulsar 3.2E Competition Pro
Reply With Quote
Old Jan 28, 2013, 07:53 AM
What could possibly go wrong?
nickchud's Avatar
Market Harborough
Joined Apr 2006
3,616 Posts
Yes I would. +ve incidence behind the CoG should push the nose down as power increases. I think you said that you were getting the opposite effect. The classic way to test this, I think, is to trim your plane for a fast cruise, then get onto an upwind path, straight and level and, as it comes past you, cut the throttle. If the plane immediately kicks upwards, your motors have been pushing the nose down, so you would need less +ve incidence (or more negative.)

It doesn't take much.

Nick
nickchud is offline Find More Posts by nickchud
Reply With Quote
Old Jan 28, 2013, 08:13 AM
OY-5542
Chrizz's Avatar
Denmark, Central Denmark Region, Silkeborg
Joined Nov 2009
725 Posts
Hi robusp!

You're right about how to mount the motor, but you have to be sure that the undesired flight-carateristc isn't due to the CoG and/or the decalage of the canard/wing... before looking to much at what effects the motor's thrust might induce. Are the undesired effects due to general acceleration or the thrust-line the motor induces??
Maybe, get it up high and make some glidetests. Maybe you'll notice similar effects when obtaining higher speeds during such glidetests, then you'll be able to determinate if the undesired effects are solely due to thrust, or acceleration in general.
Still, it's very likely, that you'll want to have some incidence on the thust-line, to "push the nose down" when throttleling up.

Happy landings :-)


PS @ Tick Point: I'll agree with John235...
About the CoG, it seems you're on the right track.
Concerning the first stall in the video, it looks like the CoG is to far backwards, combined with a rearward side-wind.
What then might have happened, is the wind succeeding in pushing the nose to the left (hence, the maybe to small vertical fins). Then the wing get blown by the wind from behind (airspeed drops drastically, boundary layer might have disapeared on one wing first), it also pitches up (CoG) and gets into a stall-spin... Maybe.
Chrizz is offline Find More Posts by Chrizz
RCG Plus Member
Last edited by Chrizz; Jan 28, 2013 at 09:22 AM.
Reply With Quote
Old Jan 28, 2013, 08:43 AM
Takeoff=Option Landing=Must
robusp's Avatar
USA, NY, Depew
Joined Jan 2009
782 Posts
Thanks guys.

Climbing on power does indicate not enough positive trust angle.
The plane trimmed for 1/2 throttle flies level.
I don't think it needs much. I try one shim at first.

This week I should also get props. I would like to run 4.1x4.1, but smallest counter rotating ones i found where 4.5x4.5.

The ones I am using are 6x4 cut down to 4x4. And you know, when you cut so much at this size the efficiency and performance is gone.

Rob
robusp is online now Find More Posts by robusp
RCG Plus Member
Latest blog entry: Pulsar 3.2E Competition Pro
Reply With Quote
Old Jan 28, 2013, 09:25 AM
OY-5542
Chrizz's Avatar
Denmark, Central Denmark Region, Silkeborg
Joined Nov 2009
725 Posts
Hi robusp!

Don't forget that, it is normal (and desired) that most planes pitches up when throttle is applied... also lifting canards.
Now there's pitching up and pitching up a lot :-)
Chrizz is offline Find More Posts by Chrizz
RCG Plus Member
Latest blog entry: Oxy 0.5
Reply With Quote
Old Jan 28, 2013, 09:55 AM
Takeoff=Option Landing=Must
robusp's Avatar
USA, NY, Depew
Joined Jan 2009
782 Posts
Chrizz,

You are absolutely right.
I like to have little climb on power, unless it's a (2kW) high performance glider.

I will also try some programming changes.
I'll leave it like it is on high rates, but will differentiate how much elevator is on elevons and how much on canard. So in mid position I'll have a 50/50 split, on high I'll do 90 canard, 10 elevons, on low 10 canard, 90 elevons.

Next, I have to see how slow can I safely go and still have control.
Rob
robusp is online now Find More Posts by robusp
RCG Plus Member
Latest blog entry: Pulsar 3.2E Competition Pro
Reply With Quote
Old Jan 28, 2013, 02:07 PM
Registered User
Tick Point's Avatar
Joined Mar 2008
511 Posts
I've added winglets (vert stabs at the tip) for the next flight. If that helps, then I may enlarge the original fins and lose the winglets so it stays true to the model.

The first flight has two video angles, one view from the ground, the other on board. From the onboard camera, you can see the launcher begin to applaud as it stays level and rises for about 3 claps, then pow massive stall.

The stall is so sudden and not at all like the soft stall I thought I'd be dealing with on a canard.
(EDIT; The stall I see from the video is in yaw. I suspected yaw stability might be an issue with the Shinden. The last launch in the video shows what I think to be several quick pitch stalls just over the bushes, right after launch. Those are the soft stalls I thought a canard would have)

I'll measure where the CG is when I get home to compare it to the CG Calculators.

thanks for the advice
Dave
Tick Point is offline Find More Posts by Tick Point
Last edited by Tick Point; Feb 02, 2013 at 09:06 PM.
Reply With Quote
Reply


Thread Tools