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Old Jul 27, 2011, 10:29 PM
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wheelspinner20's Avatar
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I made one from a scavenged atx pc power supply. firing strips (1x2 pine) and very comon hardware.

I have seen even simpler ones work powered by a dumb transformer based car battery charger.

If you had a really flat surface big enough, and fixed the wire with a 1/4" gap above that, it might turn out good enough to use.

P.
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Old Jul 27, 2011, 10:31 PM
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This is how I did the atx supply..... I also use it to power 2 at a time accucell-6 lipo chargers. (Too cheap to go buy a marine battery)

http://www.wikihow.com/Convert-a-Com...b-Power-Supply
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Old Jul 27, 2011, 10:36 PM
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I did not do the power supply like this, but I did use his idea for a bow style wire holder, then I adapted it and mounted it verticle to a small table for another style of cutter.

I use it to layer my .25" multiple pieces and cut 4 at a time etc. I also use it to cut down 2" pink etc....


http://www.instructables.com/id/Hot-wire-foam-cutter/
P
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Old Jul 28, 2011, 06:03 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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Quote:
Originally Posted by b-29er View Post
Unfortunately, it's not a matter of much choice. I have a board if 1/2" pink foam, and can't really get my hands on the 1/4 atm.
Does it have any markings on it? Is there a plastic or paper or foil skin on one side?

There several brands or types of foam and they have different qualities. Some are more useful than others.

I know that if I started slicing the 2" blue board I use for monoblocs into 1/4" slices it would not be anywhere near as strong or useful as the bundle of FFF that is standing in the corner.

One of the great tragedies in any hobby is that we can't all afford or sometimes even find the same materials that are working good for others.

Jack
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Old Jul 28, 2011, 09:06 AM
Watt Waster
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Joined Oct 2010
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Other Foam Options

Quote:
Originally Posted by jackerbes View Post
... we can't all afford or sometimes even find the same materials that are working good for others. Jack
A very true statement, if ever one was made. I was looking for Dollar Tree foam board, called Readi-board, and the two stores in the town near by didn't carry it. After talking to the manager, she recommended I do an Internet order since the company had a website for that purpose. I ordered two boxes and didn't have to pay shipping since I was willing to pick them up at the store after I was notified of arrival. I was also able to order other colors besides white. I ordered one box as black, and the foam between the paper sheets is black. They also have a gray foam core option. As others had reported, the paper does come off with very little effort after a spray down of a window cleaner product and an hour of air drying so the paper regains a little strength.

Others have said they had ordered successfully Fan Fold Foam (FFF) from a local hardware and lumber store/warehouse. In a few cases they ordered using the Internet site for the company, which offered special orders, and in some cases, home delivery for a additional fee. In each case, shipping was free if you would pick up the special order at the local store when notified of arrival. For some of us, this process may be the best and only way to get specific foam boards we are seeking. As for me, I discovered the FFF was carried by one of the four lumber and hardware stores near the hotwater tanks and parts. Seemed like an odd place to put it, but they do keep a fair supply on hand. One catch is the top and bottom sheet is often damaged.
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Old Jul 28, 2011, 12:20 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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"..One catch is the top and bottom sheet is often damaged..."

That can be a good thing sometimes. When I found a damaged bundle I got it for half price and the damage probably did not cost me 1/2 of one sheet.

You can buy Elmer's Foam Board in many places (Office Depot for example) but it is much more expensive than Readiboard and the paper is about 5 to 10 times as hard to get off.

Jack
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Old Jul 28, 2011, 05:02 PM
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Joined Jul 2006
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Quote:
Originally Posted by jackerbes View Post
Does it have any markings on it? Is there a plastic or paper or foil skin on one side?

There several brands or types of foam and they have different qualities. Some are more useful than others.

I know that if I started slicing the 2" blue board I use for monoblocs into 1/4" slices it would not be anywhere near as strong or useful as the bundle of FFF that is standing in the corner.

One of the great tragedies in any hobby is that we can't all afford or sometimes even find the same materials that are working good for others.

Jack
I had pinkfoam. And the reason i could not get foam is i have been unable to get to the store. Got to go today, so i shelled out the 34 bucks and now have a nice, blue bundle of triple-F to go with my 1/2" pink skinned foam.

here's my setup for mine, tell me if you see a problem

60'' variant
Hobbyking donkey motor with 60a ESC (the largest one)
4s 5000 lipo
will this work? i'm also planning on hauling some fpv gear
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Old Jul 28, 2011, 05:29 PM
Buzz Run Extraordinare!
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just a quick question, what do i use for the 60" fuse plans?
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Old Jul 28, 2011, 06:23 PM
Jack
USA, ME, Ellsworth
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Originally Posted by b-29er View Post
just a quick question, what do i use for the 60" fuse plans?
It will do you well to read through the list of plans in the ** Tony65x55 ** planes and plans thread.

This post has the plans for the Blu Baby AP1, there are also plans there for the different wings you can use on that.

http://www.rcgroups.com/forums/showp...&postcount=107

Don't think we are not sympathetic about the complexity of coming on board here and figuring things out. But you should have been here in the old days before we had the threads that simplify that now... It was really tough in the old days! It was like walking 3 miles to school uphill both ways!

Time has passed, things have evolved, I think there is another good choice for a wing for the AP1. That would be a 52 to 60 inch (adding more span for heavier loads) KFm3 or KFm9 wing with polyhedral tips. But there is not a plan for that wing yet and you would be plowing new ground. You could go down in history as the first person to build one!

Here is the details on how to build it just to give you an idea as to how to do that, you would just have to work out the dimensions for the planes you want to build:

KFm2 Wing with Polyhedral Tips - Part 1 - http://www.rcgroups.com/forums/showp...6&postcount=36

If you want to build a big wing that can be broken down for easier transport or storage, look at how I made the 96" KFm8 wing for the Big Blu 96 glider in this thread:

http://www.rcgroups.com/forums/showthread.php?t=1470211

That has a three section wing with fiberglass tubes and rods used for combination spars and wing panel joiners. That is is big, soft flying, and flexible wing. It might make a great choice for a AP platform because the wing will absorb a lot of the motion and that might otherwise get to the camera:

Big Blu 96 - 96" KFm9 Winged Glider - http://www.rcgroups.com/forums/showthread.php?t=1470211

Look at Big Blu 96 in some flight testing yesterday, that is one big, graceful, slow flying plane! Look at the flex in that wing!

Big Blu 96 Flight Testing #1 (5 min 27 sec)


Welcome to Blue Baby land! The University of Kline-Fogelman is right across the street!

Jack
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Old Jul 28, 2011, 11:52 PM
In Rc for a LONG TIME FFAA#1
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Canada, ON, Ottawa
Joined Jun 2004
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Spoke with the master of the blue baby today and he is going nuts at work but is very happy to hear what is going on and is going to try to get some time to visit me and i will take some pics and post them and may be even post a plane such as a t......... ah ah ah not gonna say!!!
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Old Jul 28, 2011, 11:52 PM
Watt Waster
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Joined Oct 2010
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Very nice! I will have to look at the details of the long, break down wing also. I am thinking of trying my hand at a BB50 in the near future. I want to get into the big birds also. Already ordered some 4s batteries in the 1Ah range. Got a few motors I need to check out with a watt meter while on 3s and 4s packs. Once I think I have a good combination, I will be hot to build a BB## for it. Then it will be time to search for what others did in the size, or near it for details.
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Old Jul 29, 2011, 12:14 AM
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USA, CA, Healdsburg
Joined Dec 2007
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BB 42 CG Problems

Read through most of the thread (lots to read), researched and built a bb42 with a KFM3 wing. I decided use a spare power system that I had around. It seems to pull just fine (I'll get to the component specs in a minute). My problem is that when I set the CG at 1/3 of the wing chord (about 3.25"), it flew extremely tail heavy. I'm a reasonably accomplished pilot and was able to avoid a crash and got it back on the ground.

I ended up moving the CG to about 2.25" from the LE by adding weight to the nose and it flies better but not very well. It still flies tail heavy with a high sensitivity to up elevator and little effect from down elevator. It also "wallows" at any speed and doesn't want to track straight at all.

The specs: AUW: 785g (wing 216g), Turnigy 2217 860KV motor, 11x4.7 prop, 30A ESC, 1300mAh 3S, HXT900 servos, 5A BEC, hot glue hinges (no binding), and I built the KFM3 wing with 1" dihedral.

I've played with trims, adjusted the travel limits, and mixed throttle and elevator (this helps). I checked the incidence between the bottom of the wing and the elevator. I checked the symmetry of all of the controls. The fuse/rudder are aligned and the elevator / wing are at right angles to the rudder. All of the servo horns are set up to pull directly over the hinge.

Should I keep adding weight to the nose until it flies right? I'm not sure that's the best approach, there must be something else wrong. My initial thoughts for the plane was to set it up and give it to a friend who wants to learn to fly. From the reports this plane should just fit the bill. So any ideas on how to proceed would be greatly appreciated.

I know a picture would help, but the plane is 150 miles away from me right now and I've been pondering what to do next once I get back home.

Thanks, Paul
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Old Jul 29, 2011, 12:39 AM
-Daniel
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United States, TX, Ennis
Joined Mar 2008
177 Posts
Cruel laserman, just cruel.

Hey Paul, are all of your electronics moved as far forward as possible? My BB42 balanced just fine with the servos just aft of the monoblock and esc, rx in the fuse at the LE of the wing.

What is your motor thrust angle? Perhaps it needs some down thrust.
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Old Jul 29, 2011, 12:51 AM
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USA, CA, Healdsburg
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Quote:
Originally Posted by RCDUD3 View Post
Cruel laserman, just cruel.

Hey Paul, are all of your electronics moved as far forward as possible? My BB42 balanced just fine with the servos just aft of the monoblock and esc, rx in the fuse at the LE of the wing.

What is your motor thrust angle? Perhaps it needs some down thrust.
Daniel,

My electrical setup is nearly the same as yours. I've forced the CG to be far forward of the design point by adding weight to the nose. I've used wheel balancing weights with adhesive on them inside the motor mount area to get the CG to a point where the bb will fly.

Good point on the down thrust, I forgot to mention that I've got about 6 degrees of down thrust that I've adjusted a bit. I've tried as little as 3 and as much as 10 degrees (approximately). I've also experimented with a small amount (about 2 degrees) of right thrust as well. I used washers under the motor mounts to play with the angles.

Thanks, Paul
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Old Jul 29, 2011, 05:42 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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BB 42 CG Problems...

Wow, that is pretty much a stumper. It sounds like you have covered all the corners. I was thinking wing incidence but you say you covered that (it is at zero to the hstab, right?).

Then I was thinking maybe it was might have a lighter motor, but 70 grams should be about right up there. And 150 to 175 Watts and about one and a half pounds of flying weight should do fine too.

I had a BB 33 that did something similar, flew nicely and the tail was visibly low, and adding a FFF shim under the trailing edge of the wing to change the wing incidence brought the tail right up. So I just glued the shim in place. And that is to easy to test.

When you have it trimmed out for a nice mid throttle or so level cruise and land it, is the elevator trimmed down a little? That would be evidence of a need to "hold the tail up" in flight and that speaks of a need to get a more neutral or slightly nose heavy CG.

I've become a big fan of the dive test for CG testing, especially on planes that have a lighter wing loading and a good glide. The way the plane recovers from that is pretty conclusive. That figure on it there as to how that works really explains it all, can be downloaded and that was a keeper for me.

Jack
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