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Old Oct 27, 2012, 10:09 PM
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Originally Posted by dz1sfb View Post
Yeh, Yeh! I hear yah. Just have not had the inspiration to continue on it right now. It is more accurately a monoblock Waco SRE. Still on the finish list.

Been having too much fun flying the 24"BB, and tried out floats on it today. Very happy with the results, though it could probably use a sub rudder. She gets a little twitchy if you slow it down too much.

Went out after the rain storms poured down this afternoon, and found a suitable puddle to try it out from. Will try to get some video. Flys very much like Tomas' 28"BB on floats.

Ken
Have built 4 BB 33's with UC wings, 1 BB 33 with an Exair Armin wing. All fly like a dream. I am now building a 24" to fly around a medium size pond in the area. Like the float ideas, plans, and pics. Could you provide a pic of the underside to the plane with attachment points and methods? Would be greatly appreciated.
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Old Oct 27, 2012, 11:06 PM
Slipping the Surly Bonds
dz1sfb's Avatar
Attica, MI
Joined Dec 2006
10,672 Posts
Quote:
Originally Posted by davearl313 View Post
Have built 4 BB 33's with UC wings, 1 BB 33 with an Exair Armin wing. All fly like a dream. I am now building a 24" to fly around a medium size pond in the area. Like the float ideas, plans, and pics. Could you provide a pic of the underside to the plane with attachment points and methods? Would be greatly appreciated.
Wow, thats a blast from the past!

This is the best close up picture that I have. I no longer own this plane, else I would take a couple more pics for you. Standard landing gear up front with the wheels removed.

Ken
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Old Oct 27, 2012, 11:14 PM
Slipping the Surly Bonds
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Attica, MI
Joined Dec 2006
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I am checking my CAD model to see if I have any more detail.

Ken
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Old Oct 27, 2012, 11:15 PM
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Joined Feb 2012
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Originally Posted by dz1sfb View Post
Wow, thats a blast from the past!

This is the best close up picture that I have. I no longer own this plane, else I would take a couple more pics for you. Standard landing gear up front with the wheels removed.

Ken
Is there a second attachment point behind the normal LG position? Looks as though there are two.. Can I get this info from the PDF Float plans?
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Old Oct 27, 2012, 11:25 PM
Slipping the Surly Bonds
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Attica, MI
Joined Dec 2006
10,672 Posts
Okay, I have the CAD model, but the iso view in the float plan shows the detail for the strut attachment.

Ken
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Old Oct 28, 2012, 06:04 PM
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USA, IL, Wheaton
Joined Oct 2010
553 Posts
Sir bow2
Some free flight planes use a tilt in the horizontal stab to adjust glide circle. That is, if the wing is at the same angle to the fuselage on both sides, and the stab has different angles comparing one side to the other you'll get a turn. To test this, block up the stab until it's level, and see if both the wing tips are the same amount above the surface. You can shim one side of the wing saddle to level the wing. Most kits and Arfs have a set up step where you look from the front to see if the angle from wing to stab is the same on both sides. If the fuselage hangs down a little funny, that's not the problem. Both the wing and stab need to be at the same angle to it.

If one wing tip is up with respect to the stab, it's the same as putting the plane in a bank with ailerons.

Joe
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Old Oct 28, 2012, 06:15 PM
Emress
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United States, SD, Rapid City
Joined Nov 2011
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that sounds exactly like the problem. will hopefully have time for it sometime.
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Old Oct 29, 2012, 03:13 PM
Cheese eating monkey.
France, Bretagne, Rennes
Joined Jul 2011
257 Posts
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Originally Posted by sir_clive View Post
I'd say you are too slow in turns, or your turns are too steep. Some nose drop in turns is normal (that's why one always gives some elevator to compensate).
Too large fin can also be a problem, but if your build is true to the plans, I would not consider that option.

Where is your CG at?
Sorry for the late reply.

My CG is at 59mm from the leading edge which is 2.32 inches in US money.
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Old Oct 30, 2012, 07:16 AM
Cheese eating monkey.
France, Bretagne, Rennes
Joined Jul 2011
257 Posts
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Originally Posted by Panoramix View Post
Sorry for the late reply.

My CG is at 59mm from the leading edge which is 2.32 inches in US money.
Actually on the drawings, it says between 2.30 and 2.60 inches, so I am right at the front, thus it is not surprising that it feels nose heavy.
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Old Oct 30, 2012, 07:52 AM
Jack
USA, ME, Ellsworth
Joined May 2008
17,107 Posts
Each build will vary and your placement of the battery, the wing on the plane, the motor weights varying, and all of those things will move the CG location fore and aft in the plane. So once you get to flying it you just ignore the recommended location that got you started safely and start looking for the CG location you want to fly with.

My favorite way for sorting out a CG location once I get a plane flying is the dive test. And that is explained here:

http://www.polecataero.com/handlaunchu/cg-location

And this image shows the effects of moving the CG fore and aft in the plane:

http://polecataero.com/uploads/cg_trim.pdf

When you have the CG location so it is at the point called the "rear limit of neutral stability" as shown in that image, the elevator will be trimmed flat (not up or down) and the plane will recover from the dive test. Move it from neutral to positive or negative and the recovery behavior changes.

The explanation there is for a glider but if will work also if you do it from a power off level glide with a regular plane too. The point is not that you have to put the CG at a certain spot, it is that you get the CG at the neutral point and then adjust it a little to get the behavior you want to have.

Jack
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Old Oct 30, 2012, 09:45 AM
Cheese eating monkey.
France, Bretagne, Rennes
Joined Jul 2011
257 Posts
Thank you Jack, it makes sense to me. Now I need to find some time and a large area to sort this out.
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Old Oct 30, 2012, 10:05 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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It will really help and then you'll know how to get any plane set up right.

I like to do it on a calm air day and just trim elevator to get it gliding nice and level. I want it to just glide forward and be in a slow descent. When I get that, I land and look at the elevator.

If the elevator is trimmed up it was holding the tail down so you were a little nose heavy. If it is trimmed down, it was holding the tail up and was a little tail heavy. And that, of course, is approaching a dangerous state of trim. A nose heavy airplane will fly OK but not real well, a tail heavy airplane can be uncontrollable and might not even survive the maiden flight.

So once you see how the elevator is trimmed you want to move some weight to compensate. I usually move it about 1/4" or 3/8" (6-9mm) at a time.

Then I set the elevator trim on the TX back to zero, and set the elevator to be level with the hstab using the push rod length adjustment. And I repeat the process. The next time you may or may not have to adjust the elevator to get the level glide. If it take no trim or only a click or two, you can try the dive test.

I give a small amount of forward stick/down elevator and let the stick return to the center. If the plane slowly recovers and then goes back into the forward glide it is right.

As you can see, what the response to the dive test really does is tell you if the elevator is trimmed up or down or if it is level. And when you get to the point where the CG point is just a little bit forward of the neutral point to give you some forward drive, and the elevator is level with the hstab, you are in the lowest drag mode and have the safe recovery too.

For some types of flying and to suit some tastes, people want the plane to have the CG in a place that does not even give you a safe recovery. 3D flying and aerobatics are good examples of that. Those generally want to have a slightly tail heavy trim.

Jack
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Old Oct 30, 2012, 10:21 AM
Cheese eating monkey.
France, Bretagne, Rennes
Joined Jul 2011
257 Posts
I definitely had to trim up the elevator, so that is consistent with a nose heavy plane.

I can't wait to find some time to look at this.
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Old Nov 01, 2012, 08:14 PM
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Malaysia, Johor, Johor Bahru
Joined Oct 2007
117 Posts
just wanna share my first scratchbuilt full fuse blu-baby, thanks for the great design
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Old Nov 02, 2012, 07:30 AM
More coffee, please!
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Austria, Wien, Vienna
Joined Jul 2011
658 Posts
she looks great! video, video!
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