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Old Jan 17, 2008, 09:31 AM
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If all goes well, I might be able to post a frame up photo this evening. Supposed to get the parts over lunch today. My setup holds onto the unit by holding the GWS heatsink only. The fans are tricky to hold onto without distorting them and causing the blades to touch internally. I avoid that problem by not touching them at all. Because of this setup the model will go with EDF-40, EDF-50's and 50XC direct drive very well. it might also be possible to run two of the lesser reduction LPS systems if there is prop clearance and enough prop available. I'll have to check into that one. Any 12mm motor that a GWS Heat sink will grab onto. I really expect 90% of everybody to run the EDF-40's however. It should look too cool with those on there and the performance should be great.

Dave
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Old Jan 17, 2008, 09:38 AM
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Incidentally, I don't know if 140 is going to work well here or not. This is what I'm trying on my first one. As the V gets flatter and flatter you get less yaw and more adverse roll out of it. Imagine the surfaces deflecting for left yaw, it is also right roll. I'm gambling there is enough stability that it will still roll correctly. Think about a standard rudder, it also induces an adverse roll twisting moment in the fuse. My tail surfaces are larger than yours. I'm very curious how yours flys however. If I can get away with less tail without spoiling stability at low speeds then it would help make the model faster to trim them back. Just cracking the horizontal into a V is a pretty good idea if it's enough area. I also noticed you figured out the tail slots need to be at a weird angle to end up with zero angle of attack on the V surfaces. That was tricky to work out the right angles. Roy Oetting helped me there and with some other ideas.

Wait till you all see the tail jig and spar setup I figured out for setting the tail. Also, I'm making my V tail out of 3 peices. That should give all your noodles a headache trying to figure out what that means. hehehehehe

Dave
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Old Jan 17, 2008, 07:16 PM
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Ok, we got the kit today and started framing it up. Mentally, when I submit a new file for a proto cut, I'm always thinking, this is going to be the first one I submit that goes through without an error. I get very confident in that. Then when the first one goes together, (or more correctly doesn't!) my inflated ego is relaxed to reality. I've got a few missing parts I forgot to draw, a few parts that are sized wrong, a few special rib counts are wrong and a few other minor issues. We couldn't quite get it framed up enough to shoot even a rough photo.

I plan to hit Fox in the morning and if the laser isn't already cutting the Mini Low Sticks, I'll try to sneak out some fix parts for this build.
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Old Jan 18, 2008, 03:03 AM
Fly it like you stole it..
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Quote:
Originally Posted by Carnifax
Maybe I could make a couple of small balsa standoffs. Something easily replaceable in case they get ripped away. Thanks for the tip.
Yeh, That is exactly what I did.. A nice piece of balsa and wrapped the fan unit in some sandpaper to contour the balasa standoff to fit up perfect against the fan shroud.. Then I scuffed up the fan shroud to give it somewhere to stick and voila..
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Old Jan 18, 2008, 03:12 AM
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Ok, Im getting closer and closer. I still have to get a brushed esc. A guy in our club (Sgt Dirt) is willing to wheel and deal. He has scratched up a mini stick before too.

Its pretty late now but hopefully this weekend I can get this wrapped up and maybe Saturday fly this guy!

Until next time!
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Old Jan 18, 2008, 03:16 AM
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Tram,

That is a good idea, thanks. I have this one just tacked on so it will be easy to yank off. I think I will make a standoff and go brushless!
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Old Jan 21, 2008, 12:00 PM
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Bad News. Fellow club member Sgt. Dirt hooked me up with a Pixie 20 ESC. I hooked everything up and just had to power it up to hear the whine. Everything did was it was supposed to but when I got near the high end of the throttle, the impeller blade flew off and nearly took out an eye.

Im generally pretty cautious about these situations but I guess I got a little lax. To top it off, the impeller blade is chipped and I imagine would throw it out of balance if I tried again. Luckily, by some weird simple twist of fate, my local hobby store had just ordered some last Friday. So the project is placed on hold until then.

I imagine Dave will have his done and in the air by then. I will update with progress reports when they happen.
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Old Jan 22, 2008, 05:45 PM
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Quote:
Originally Posted by Carnifax
.........

I imagine Dave will have his done and in the air by then. I will update with progress reports when they happen.

Hardly. Glad your eye is OK. Here are some shots of our Super Skunk Works project. Please note, Miss Berry Buxom just brought in a note, this information was upgraded from sensitive to For Your Eyes Only by Double Knot Command just today.

This model is Doug Hoy's, he brought it by the shop today. He's been helping debug the parts fits and is my laser cutter. This one looks like it might make the air soon. He picked up a roll of covering and two motors. So, maybe early next week if we can find a time when there are no satellites overhead. ;-)

It sits on the wheels nicely without any other gear inside in the photo. I was worried if the motor weight being so close to the CG would make it difficult to balance or not. From what I can see this will not be an issue.

The motor pylon is in a reinforced slot/box in the wing. I've designed it so the weakest point is the pylon where it meets with the wing so if you have an accident you only need a new pylon and to dig the tabs of your old one out. You won't have a huge section of your wing yanked off. Yes, that is a magnetic hatch over a buried aileron servo location. Nose hatch is magnetic as well. The wing is held on with my magnetic latch system. Pushbutton wing removal. Only visitors to the shop have seen this setup. It's pretty slick, this should be the first kit to hit the streets with this feature. Note the very low landing gear. This is my strongest wing ever. You boys can go nuts if you like on the power systems. Our first flights will be twin EDF 40's on 2S. A very stable system. I'll try to get a video of it when it happens. Sometime late this week or early next, I'll get a couple of Beta's out so some build threads can get started. This will be one of my more complex kits. I think anybody that has any of my other kits under thier belt should have no issues putting this one together. Right now we are standing at 131 laser cut parts. I apologize, I'd have gotton it up to 170 or so if I could have figured out how.

Dave
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Old Jan 23, 2008, 05:23 AM
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Carnifax progress looks great. Can't wait to hear about your flight after repairs. Dave the prototype looks great. Now the wait to see it covered and hear how if flies.
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Old Jan 23, 2008, 08:42 AM
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Another interesting note. I've been told that twins don't need right thrust as there is no torque effect on a twin even if the props run in the same direction. It's been verified to me by several educated and experienced full scale twin pilots. Counter rotating props are only for P factor and can help greatly when one engine flames out. P factor says that the downward swinging prop blade produces most of the thrust. This is because the angle of attack is positive in flight. Move your prop to the horizontal on any model, now hold it in an artificially positive attitude and look at the angle of attack of each prop blade. You'll notice one will have more effective pitch than the other. By setting a twin up counter rotating and the rotation so the top of each prop is moving inward towards the fuse you actually are placing the centerline of each motors thrust closer to the fuse than the prop shaft. The closer the thrust line is to the center of the fuse, the less rudder you need to counter offset thrust caused by engine out conditions.

All that being said, I did put 1 degree of right thrust in this airplane. If the engineers are correct (and they should be) test flights should indicate slight roll trim changes with throttle change from cruise to WOT. (If trimmed for cruise speed, I should see slight roll to right moving to WOT.) If this is the case (and I can detect it), I'll change it back to zero. So, this project is part of a learning curve for me as all projects should be for everybody. I hope each day to be smarter than yesterday. I look forward to flying this model.

If you get by the shop, say hello to Ron Lamsdale. He's been doing all my builiding of late which has free'd me up to be as prolific as possible and get many of my kit ideas completed. There are a steady stream of new kits in line to come off the laser now. Get your workbenched cleaned off and ready to rock!

Dave
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Old Jan 23, 2008, 10:13 AM
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Dave,

New Kits?!? Fantastic news! The new mini looks pretty sharp. I cant prove anything but I hold forth a theory that the magnets make these planes fly better.

A couple of quick questions based on the pictures/your description.

What will the motor mount be made of? Light ply, laminated balsa, a thicker, single piece of balsa?

Did you design the plane around a particular EDF unit?

Will you include extra mounts as part of the kit in case of breakage?

One of the criticisms that Ive read about EDF units is airflow over the motor. Did you design yours to have provide this? I really dont see how you could have any more.

Do you anticipate the use of outrunners for this or are you going to more or less leave the mods up to the speed freaks?

Will your aileron setup include torque rods in the wing or will the linkage be forced out the side of the fuselage or will it be some exotic, buried in the wing setup?

It looks like there will be plenty of room to move a battery around for the correct CG. Will the formers be low profile enough to fit, say a 3s 2100 TP (although I would imagine this kind of weight will be pushing it for this airframe)?

There has been something of a proliferation of low cost, high powered EDF Units.

http://donsrc.com/cart/index.php?act...d&productId=50

What is your anticiapted limit of power systems for this plane or are you leaving that up to peoples imaginations?

Dan

PS Good stuff about counter rotating props!
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Old Jan 23, 2008, 06:39 PM
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Quote:
Originally Posted by Carnifax
Dave,

New Kits?!? Fantastic news! The new mini looks pretty sharp. I cant prove anything but I hold forth a theory that the magnets make these planes fly better.

A couple of quick questions based on the pictures/your description.

What will the motor mount be made of? Light ply, laminated balsa, a thicker, single piece of balsa?!
That is 1.5mm thick (people call it 1/16" thick) aircraft plywood just like my firewalls on the smaller models are cut from. It's just 1 profile pylon with a notch to accept the GWS 12mm heat sink.

Quote:
Originally Posted by Carnifax

Did you design the plane around a particular EDF unit?
Yes, I was thinking of the EDF40 when I designed it. However, it will hold the 50's and direct drive 12mm motors with all the same setup. The EDF 40 looks like a more efficient package to me than the 50.

Quote:
Originally Posted by Carnifax
Will you include extra mounts as part of the kit in case of breakage?
That is very likely. Don't read me wrong, I don't expect them to be fragile. But I do try to design things so they break gracefully and can be repaired easily. Anything hanging off a wing has lots of potential to tear up the wing and a wing isn't usually simple to repair. So I felt it was a good idea to make the wing bulletproof and the pylon less so.

Quote:
Originally Posted by Carnifax
One of the criticisms that Ive read about EDF units is airflow over the motor. Did you design yours to have provide this? I really dont see how you could have any more.
I did not do anything to block any airflow. To me it seems pretty pure and clean. I'm wondering what people are doing to block airflow over the motor in fans? What I run into alot is people learn electric through 3d foamy's then move on to a warbird or racer or maybe a fan model where the average throttle position is much higher. They try to over amp the motors just like as much as what works well in a 3D model where the throttle averages 40 -60%. This just does not work when you move to models where your throttle is average 80% or better. Things get hot, smoke and stink gets out. Pilot gets what he deserves for not thinking. (oops, did I say something wrong?)

Quote:
Originally Posted by Carnifax
Do you anticipate the use of outrunners for this or are you going to more or less leave the mods up to the speed freaks?
Everybody is so in love with outrunners that they just can't believe that anything else could possibly be a better solution. People can do as the please. I invite that here. But, it's my general thoughts that up to 6-8 amps a motor, how can you possibly beat a Medusa 12mm in-runner? sure, if you want to pump more watts you need more motor mass. However, I'm thinking the finished weight will be around 7oz here. 100 watts should not be too hard to get out of two of these fans, that's 200 watts per pound, that's pretty good on simple inrunners.

Quote:
Originally Posted by Carnifax
Will your aileron setup include torque rods in the wing or will the linkage be forced out the side of the fuselage or will it be some exotic, buried in the wing setup?
Direct pushrods exiting the slots but the servo head burried. More classy, less drag. I've not decided what to name this kit yet but it's clearly more than a "stick" so I think it needs to be a little classier in the setup. However, it's setup to build with servo inside or outside just by changing the top for the bottom center sheeting.

Quote:
Originally Posted by Carnifax
It looks like there will be plenty of room to move a battery around for the correct CG. Will the formers be low profile enough to fit, say a 3s 2100 TP (although I would imagine this kind of weight will be pushing it for this airframe)?
I made it about 1/4" wider inside than the Mini Stick series so it would be friendlier to a wider range of battery packs. I think the wing loading would get a little crazy with that big a battery. Can these fans hold together with a motor capable of drawing 20 amps? I don't think that's possible (no fan expert so I might be wrong) so I don't think anybody will need a pack that large. None of my later models, this included has any type of former crossing the radio compartment. That's old time think, I let it go a couple of years ago. The Micro Bipe was the first to go formerless up front. All kits following that are formerless.

Quote:
Originally Posted by Carnifax
There has been something of a proliferation of low cost, high powered EDF Units.

http://donsrc.com/cart/index.php?act...d&productId=50

What is your anticiapted limit of power systems for this plane or are you leaving that up to peoples imaginations?
It should be at about 60-70 watts on the stock EDF40 units. I expect it would be a fun sport airplane on 50 watts or better. At around a 100 watts it's going to be a hot speedster. Remember, that's 200 watts per pound so we're getting to very high power levels there. It's not many watts but this isn't many ounces either. It's all relative. I'd anticipate a max wattage for existing gear at around 160 watts or so. Above that you'll need to go to some motor that I'm not aware of existing. But, I'm comfortable with whatever anybody wants to do here within a limit of maybe 9oz. At least those are my predictions not having flown it yet. After I fly it, I'll know more.

Our in shop model is together now, we are caught up with Doug. If the weather does not turn bad here, this model will fly next week for certain.

Quote:
Originally Posted by Carnifax
Dan

PS Good stuff about counter rotating props!
Enjoy All!
Dave
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Old Jan 23, 2008, 06:50 PM
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Another interesting note. After we get this one done and working well, I'm very likely going to make a double size version of it. It's easy to double the drawing and the thickness of 1/8" is about right for a near 48" model anyway. Few adjustments would need to be made. 1/32 D tube sheeting becomes 1/16", 1/16" fuse sides become 1/8", you know the drill.......

All the big hours of work go into the first version of a model.

Dave
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Old Jan 29, 2008, 11:01 AM
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Ok, Doug has his completed. He had it in the shop yesterday evening. We wattmetered it at 7.2 amps, little over 50 watts. It's finished weight with a 600 size pack. He had an X-brand control which seemed to start the motors at 20% throttle and had a brake that could not be disabled. So, he's updating it with a Castle Pixie 20P. This should get him smoother throttle. It feels like it's going to have oodles of power. Also, weirdly, I think it will sustain flight well below 50% throttle just from the feel of the thing. I've always felt EDF units are not doing much until you get the RPM up real high, maybe I've been wrong.

The only thing that stopped us from test flying yesterday was an intermitant servo (thankfully not Radical product). So, he's due to change that out. It's windy here today so things will be on hold. Trouble is, tommarrow is the beginning of the next ice age. Brrrrrrrr...... Why doe anybody choose to live in Ohio?

Dave
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