HobbyKing.com New Products Flash Sale
Reply
Thread Tools
This thread is privately moderated by ExperimentalAir, who may elect to delete unwanted replies.
Old Mar 08, 2012, 01:49 AM
Long Range FPV'er
Joined Feb 2009
575 Posts
Quote:
Originally Posted by hoppy View Post
While waiting for Ed, let me make a suggestion.

Make the main wing and cut it in where you want the dihedral or make a separate dihedral section. Sand or cut the proper dihedral angle into the mating edges and do one of two things.
#1 - Glue a piece of foam over the cutoff portion to close the wing opening. Do the same on the other side. Then trim to match the airfoil and glue them together. Or, cutout plywood dihedral spars to fit on each side of the main spar and insert into each wing piece. This will provide the correct dihedral and strengthen the joint. Epoxy all together.

To provide additional strength if needed, cover about 1" on each side with newspaper and attach with 50/50 water-elmers glue.
Thanks Hoppy...
Mykro is offline Find More Posts by Mykro
RCG Plus Member
Reply With Quote
Sign up now
to remove ads between posts
Old Mar 08, 2012, 07:27 AM
Ed @ Experimental Airlines
ExperimentalAir's Avatar
United States, AZ, Phoenix
Joined Sep 2011
459 Posts
Quote:
Originally Posted by Mykro View Post
Ed,

Do you know of a technique to put Polyhedral/Dihedral in the Armin wing??
Hoppy's suggestion is a good one. For wingtip polyhedral I might only add an idea to cut angled little spar sections from Coroplast (stronger) or foamboard (more available), like flattened L's, with each leg being about 2" long and the width matching the inside dimension of your wing, between upper and lower surfaces. The tension across the lower surface joint and the compression across the upper surface joint can be addressed with foamboard, paper, glue, etc. But there is a compressive, "wrinkling" force at the polyhedral joint that wants to squish the upper and lower surfaces together as force is applied across the polyhedral. Putting some non-compressive substance inside at the point of transition can help prevent that and bolster the whole thing.

For centerline dihedral on anything but the lightest wing loading I might suggest using true spars (carbon, wood) coupled in the center with an aluminum tube that has been bent to the desired angle, preferably with a tubing bender or with sand or ice inside to get a consistent bend. Plug in the right and left spars and finish the actual wing surfaces to mate up nicely as you want.
ExperimentalAir is offline Find More Posts by ExperimentalAir
Reply With Quote
Old Mar 08, 2012, 07:28 AM
Ed @ Experimental Airlines
ExperimentalAir's Avatar
United States, AZ, Phoenix
Joined Sep 2011
459 Posts
Quote:
Originally Posted by rnmosaic View Post
Ed,

Thank you for excellent ideas and costs unbelievable to make.

Here is my "Boxer" as my 6 year old calls it .. and it is one of the most amazing planes to fly ...

Thanks
- Mosaic
That's a beauty! If you make a video please post it as a response to one of mine (Noob Tube?) and I will accept. Thanks for sharing it.
ExperimentalAir is offline Find More Posts by ExperimentalAir
Reply With Quote
Old Mar 08, 2012, 07:31 AM
Ed @ Experimental Airlines
ExperimentalAir's Avatar
United States, AZ, Phoenix
Joined Sep 2011
459 Posts
Quote:
Originally Posted by englanito View Post
I probably missed it but what size cord wing did you use for your noob tube?
5" , 6" or 7"
I used the 5" airfoil chord + 1 1/2" control surface for 6 1/2" total chord. 1" control surface is really adequate for roll control but 1 1/2" is just a little more sturdy, and has more material to accept the control horn, which is why I usually go a little bigger.
ExperimentalAir is offline Find More Posts by ExperimentalAir
Reply With Quote
Old Mar 08, 2012, 07:45 AM
Ed @ Experimental Airlines
ExperimentalAir's Avatar
United States, AZ, Phoenix
Joined Sep 2011
459 Posts
Quote:
Originally Posted by RCTyp View Post
Here is what I am feeling. With the high efficiency wing it wants to make longer lines, and when the wind is gusty and I have a light plane like these I sometimes have some very difficult turns when the wind dies and I am suddenly stalling in a turn and have to throttle up to avoid the dive and I end up flying fairly high up and fast to avoid the problems.

But if I had a higher drag wing with the same lift I would be giving it more throttle at a slower airspeed. Then when the wind direction changes, the plane will respond much more quickly by itself (it has a higher prop push happening) and I won't experience the same tip stalls due to variable winds........
I think you're kind of on the right track, but there may be a couple of more direct ways of thinking about getting better control authority.

The simplest one, which you mention, would be to reduce your aspect ratio by increasing chord and/or reducing wingspan, plus using amply sized control surfaces - like 1 1/2" - with generous throws. This will give you much more roll control authority. For pitch it's mostly a matter of elevator size, throw, and distance from the CG - the more of each the better the pitch control.

Second, wing loading has a lot to do with the "floatiness" of a plane, so perhaps you just need relatively smaller wings, or more weight on board, for any given plane. The expense will be an inherently faster flying plane. I'm not sure that's what you want in an enclosed area though.

As for literally adding drag in order to require more power I think that's kind of the realm of some profile foamy 3-D planes, which I do not fly. They appear to be incredibly agile and good for tight spaces but I have to think they wouldn't do so well in the wind.

As a general rule keeping the CG generously forward will help with native pitch stability (well, yaw too) as well as "making you fly a little faster" at trim, which can improve control authority.

Sorry that's kind of all over the place. Maybe you could post photos of your planes and the pros and cons as you perceive them and we can make some detailed suggestions.

Peace,
Ed
ExperimentalAir is offline Find More Posts by ExperimentalAir
Reply With Quote
Old Mar 08, 2012, 09:12 AM
Crash Test Engineer
United States, MN, Maple Grove
Joined Nov 2011
110 Posts
I have a motor mount question - any insights from the group are appreciated (Ed, I sent you msg via You Tube on this too).

I bought some 1 1/2" X 1/8" thick aluminum bar stock at Home Depot.

Is this too thick for a motor mount? How would you recommend bending it to about 85 degrees (mount for the Axon). I do not have any presses or brakes available to me, but do have a vice (woodworking type) on my bench.

I thought I would try to bend it around a screwdriver in the vice. Any other ideas or recommendations. I have done a little research and do not think heating it will be necessary, but not entirely sure.

Thanks in advance!
RC Dad is offline Find More Posts by RC Dad
Reply With Quote
Old Mar 08, 2012, 11:53 AM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
21,187 Posts
IMO, 1/8" is much too thick - 1/16" would be plenty for most motors.

How large is your motor? In max amp draw that is.

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
WOW Ed, didn't take long to top 10,000 views......100,000 by Dec?
hoppy is offline Find More Posts by hoppy
Last edited by hoppy; Mar 08, 2012 at 12:07 PM.
Reply With Quote
Old Mar 08, 2012, 01:19 PM
Crash Test Engineer
United States, MN, Maple Grove
Joined Nov 2011
110 Posts
Quote:
Originally Posted by hoppy View Post
IMO, 1/8" is much too thick - 1/16" would be plenty for most motors.

How large is your motor? In max amp draw that is.
I agree I would like 1/16th, but have not been able to find it.

The motor I will be using is the Turnigy SK3530-1100. It weighs 79 grams and says it draws 30 amps (250 watts). I do not have a watt meter so have not measured what it actually does. I will be putting a 6X4 prop on it.

I am going to check out Northern Tool to see if they have any other stock sizes.
RC Dad is offline Find More Posts by RC Dad
Reply With Quote
Old Mar 08, 2012, 01:32 PM
Ed @ Experimental Airlines
ExperimentalAir's Avatar
United States, AZ, Phoenix
Joined Sep 2011
459 Posts
RCDad - there are some kind of so-so steel L-brackets for framing (as in studs) that are thinner, still pretty heavy, but worth comparing to the aluminum. License plate aluminum was a cool idea. You might also want to go somewhat bigger with that prop, like at least 8 or 9 x3.8 or x6. That's a pretty torque-y motor. 9x6 is the actual recommended. Unless you're putting it on an Axon, in which case I would think about a 3-bladed 6x5 or 6x6.
ExperimentalAir is offline Find More Posts by ExperimentalAir
Reply With Quote
Old Mar 08, 2012, 01:46 PM
Crash Test Engineer
United States, MN, Maple Grove
Joined Nov 2011
110 Posts
Thanks ExAir. I will check out the framing brackets (and for your You Tube response). I am using this on the AXON. I will play with the mounting angle and height to accommodate a larger prop.

I also have the Greyson Hobby Microjet V3 motor. Maybe that would be a better option for this plane.
RC Dad is offline Find More Posts by RC Dad
Reply With Quote
Old Mar 08, 2012, 04:35 PM
Long Range FPV'er
Joined Feb 2009
575 Posts
Quote:
Originally Posted by RC Dad View Post
I have a motor mount question - any insights from the group are appreciated (Ed, I sent you msg via You Tube on this too).

I bought some 1 1/2" X 1/8" thick aluminum bar stock at Home Depot.

Is this too thick for a motor mount? How would you recommend bending it to about 85 degrees (mount for the Axon). I do not have any presses or brakes available to me, but do have a vice (woodworking type) on my bench.

I thought I would try to bend it around a screwdriver in the vice. Any other ideas or recommendations. I have done a little research and do not think heating it will be necessary, but not entirely sure.

Thanks in advance!
I'm using these "Simpson strong-tie" straps for motor mounts I bought from my favorite "Home Improvement Store"... Any lumber yard would carry Simpson Strong-tie straps and hold downs too...


The pictured strap is 1 1/4" wide x 12" long and is 20 gauge thick (32mm x 304mm x .90mm) They come in different lengths.. I can fabricate two motor mounts from a 12" (304mm) length strap for under a dollar a strap.. These motor mounts are easy to bend, super strong, lightweight, and won't flex.. Oh.. and galvanized to boot!
Mykro is offline Find More Posts by Mykro
RCG Plus Member
Reply With Quote
Old Mar 08, 2012, 05:30 PM
Crash Test Engineer
United States, MN, Maple Grove
Joined Nov 2011
110 Posts
Mykro - Thank you! I will be returning the bar stock and will get some of the Simpson tie straps. Much appreciated!
RC Dad is offline Find More Posts by RC Dad
Reply With Quote
Old Mar 08, 2012, 05:48 PM
Ed @ Experimental Airlines
ExperimentalAir's Avatar
United States, AZ, Phoenix
Joined Sep 2011
459 Posts
Yes, those things. Thanks Mykro.
ExperimentalAir is offline Find More Posts by ExperimentalAir
Reply With Quote
Old Mar 08, 2012, 06:02 PM
Long Range FPV'er
Joined Feb 2009
575 Posts
Quote:
Originally Posted by RC Dad View Post
Mykro - Thank you! I will be returning the bar stock and will get some of the Simpson tie straps. Much appreciated!
When I get my wing all complete I'll post a few pics...
Mykro is offline Find More Posts by Mykro
RCG Plus Member
Reply With Quote
Old Mar 09, 2012, 04:12 PM
Registered User
United States, NY, Albany
Joined May 2006
22 Posts
Hi Ed;
Great videos,(nice hair,ha,ha), I've been balsa building for 25 yrs.
and have now been turned on to foam board. Built your axon trainer
this week. I will have to practice more on tubes to make them exactly
square. I love Canards, and will be designing one soon. No more big
$$$ on planes. Keep the videos coming

Bob
61rcpilot is offline Find More Posts by 61rcpilot
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Build Log SEW-SLO 30" Foamboard Wing Atx_Heli Foamies (Scratchbuilt) 65 Yesterday 04:14 PM
Build Log SEW-SLO 30" Foamboard Wing Atx_Heli Flying Wings 0 May 19, 2011 10:47 PM
Question So I have a sheet of $Tree foamboard... what to build? Bomb Dropper Foamies (Scratchbuilt) 15 Mar 23, 2011 03:49 PM
Discussion EDF/Motor for University Design Project uwpropulsionguy Electric Ducted Fan Jet Talk 0 Mar 06, 2011 04:24 PM