Espritmodel.com Telemetry Radio
Reply
Thread Tools
Old Jan 16, 2012, 11:31 PM
Registered User
crawlspace's Avatar
Pacific Northwest
Joined Jan 2009
355 Posts
I had to go take a peek at the Botali you mentioned and your right, it isn't very attractive. I also checked out some of Tim Hooper's models and came across the Siebel Si201, another real stinker in the looks department IMO.

Mike
crawlspace is offline Find More Posts by crawlspace
Reply With Quote
Sign up now
to remove ads between posts
Old Jan 17, 2012, 12:01 AM
Registered User
crawlspace's Avatar
Pacific Northwest
Joined Jan 2009
355 Posts
The fuselage basically consists of two segments. The cockpit surround and nose are made up almost entirely of 1/8" lite ply while the aft section is traditional open structure made up of square balsa stock. Rather than build the entire side and "crack" the angular changes afterward I took a cue from the plans and will build the aft section and fore section separately then join them when I stand the sides up. The longerons and uprights are 3/16" square while the diagonal bracing is 1/8" square and set back from the outside so they don't show through the covering. The left side is shown with the diagonals installed flat to the board. The right side can be built on top of, or in the same orientation as, the left but will need to be flipped over before adding the diagonals.

Pete,

The bottom longerons exceed 36" and I'm not too keen on scarfing together pieces if I don't have to so I modified the tail post as shown. Maybe you could add this as one piece to the 3/16" sheet, that way the next guy can set it aside and fabricate his own like I did with the stab parts.

Mike
crawlspace is offline Find More Posts by crawlspace
Reply With Quote
Old Jan 17, 2012, 11:51 AM
Registered User
Norfolk, England
Joined Sep 2001
7,600 Posts
Probably the only advantage of metric balsa is that it comes in metre lengths - 39 3/8".
Point taken, leave it with me.

Pete
PETERRAKE is offline Find More Posts by PETERRAKE
Reply With Quote
Old Jan 19, 2012, 02:53 PM
Registered User
crawlspace's Avatar
Pacific Northwest
Joined Jan 2009
355 Posts
Fuselage construction continues with the cockpit/nose assembly. I have included step by step pictures of the procees I used to get all of these pieces together. The firewall and rear former are shorter and need to be centered on the cockpit sides in order to make space for the u/c and pylon wires that will be lashed along the top and bottom edges. The next step is to figure out where the control lines will run and finalize servo locations before joining the fuse components.

Pete,

This leads me to a question, in the last picture in post #10 the control arm for the elevator can be seen and appears to be a pull-pull setup but the men in the photo are standing where the control line would be if the line runs off the top of the arm and into the fuse side. Based on the suggested servo locations on the plans these lines would have to run through the stab itself, this is also suggested by the first illustration in the thread. I don't know if there is any other way to do it.

Mike
crawlspace is offline Find More Posts by crawlspace
Reply With Quote
Old Jan 19, 2012, 02:55 PM
Registered User
crawlspace's Avatar
Pacific Northwest
Joined Jan 2009
355 Posts
Quote:
Originally Posted by PETERRAKE View Post
Probably the only advantage of metric balsa is that it comes in metre lengths - 39 3/8".
Point taken, leave it with me.

Pete
Interesting, the widths are still imperial but the lengths are metric?

Also, I'm beginning my search for a power set and was wondering if you had any idea of what the expected AUW will be. The plans recommend an AXI 4120/12, those were designed for sport planes up to 7 lbs and sailplanes up to 10 lbs. I just can't see this plane getting above 5 or 6 lbs but I really don't know. I just did a preliminary weight check of all the parts and components and, using the recommended motor and a 3s 3200 pack, total uncovered/unrigged weight is 56 oz (that includes 6 oz for wire wheels).

Mike
crawlspace is offline Find More Posts by crawlspace
Last edited by crawlspace; Jan 19, 2012 at 04:53 PM. Reason: added information
Reply With Quote
Old Jan 19, 2012, 06:27 PM
Registered User
Norfolk, England
Joined Sep 2001
7,600 Posts
Mike,
I can't actually see any cables at all on that photo, so possibly the aircraft is incomplete. However, I can see what appears to be a cable exit point on top of the fuselage just above that chap's arm. That seems a logical position for them to enter, before bending towards the servo - with the aid of a nylon tube. I checked the lines and, if the exit is immediately in front of the crossbrace one away from the tailplane, it works out pretty well.
As regards the AXI, when I drew this up, that was a motor I had available. IIRC, static tests proved that it will swing a 17" prop, on a 2s pack, for under 30 Amps. I was aiming at around 4.5 lb, so that's not too far out for the power levels I usually fly at - somewhere in the region of 200 watts.

Pete
PETERRAKE is offline Find More Posts by PETERRAKE
Reply With Quote
Old Jan 19, 2012, 07:31 PM
Registered User
crawlspace's Avatar
Pacific Northwest
Joined Jan 2009
355 Posts
Pete,

Thanks for the prompt reply, that gives me some good information to work with. I've got one more, how much throw do you think the wing warp servo will need? the servo sits just below the cockpit floor and doesn't leave a lot of space for the servo arm travel. Right now I'm planning on using a JR ST126MG servo I have laying around that will provide 10mm total travel at the end of a 20mm arm without modifying the existing servo cutout, do you think that will be enough?

Mike
crawlspace is offline Find More Posts by crawlspace
Reply With Quote
Old Jan 20, 2012, 02:48 AM
Registered User
Norfolk, England
Joined Sep 2001
7,600 Posts
Mike,
Personally I'd go for more throw if you can arrange it. In your case that may well involve cutting clearance in the cockpit floor - I'll raise the one on the drawing. You may not actually need the extra throw, but better to have it and not need it....
Remembering the arrangement on the Ponnier there will be losses through the idler cable, so you're likely to find yourself with more down than up. Too much throw will just result in adverse yaw - like the Ponnier which turned right with either stick deflection until I took out a little left bias and reduced the throws.

Pete
PETERRAKE is offline Find More Posts by PETERRAKE
Reply With Quote
Old Jan 25, 2012, 12:09 AM
Registered User
crawlspace's Avatar
Pacific Northwest
Joined Jan 2009
355 Posts
I have all the servos mounted and a plan for routing the control wires. As Pete has suggested, the top elevator wire will run through the top of the fuse at the crossbrace forward of the stab. The bottom one will run through the side at the same place just below the top longeron. I used 1/16 balsa for a flush mount gusset that sits against the recessed 1/8" diagonal and is backed with a bit of 1/16" ply. The rudder controls will enter the fuse sides at the stab leading edge upright so that got the same balsa/ply mount combo, these will be drilled for a piece of tubing which will guide the wires. I've already added the tubing to the servo bay as pictured below. I also added the balsa step to the fuselage sides and have now come to the realization that this is probably a left side only feature so I need to remove it from the right.

I also realized the fore fuse section is much easier to work on without the tail attached so I'm going to continue assembly on the nose and undercarriage before attaching the aft framework.
crawlspace is offline Find More Posts by crawlspace
Reply With Quote
Old Jan 27, 2012, 01:33 AM
Registered User
crawlspace's Avatar
Pacific Northwest
Joined Jan 2009
355 Posts
Pete,
While working on the undercarriage I have run into another small road block and it once again involves material and my lack of experience. I'm not quite sure what type of bamboo (split or reed) the skids are to be made from and I don't think I can get either. I see they were round in the pictures but I can't tell what they're made of originally. Did you specify it solely for it's strength or do looks play a part? What else would you suggest I use?

Thanks,
Mike
crawlspace is offline Find More Posts by crawlspace
Reply With Quote
Old Jan 27, 2012, 03:35 AM
Registered User
Norfolk, England
Joined Sep 2001
7,600 Posts
Mike,
It was purely for strength that I list bamboo. Nothing else comes even close to as strong and flexible. You're telling us you can't get heavy duty garden canes where you are? I thought they were pretty common just about everywhere.
If you can, get one with the longest joints possible, and the biggest diameter (the two usually go together) and use an old kitchen knife to split it into strips. In the past I've then planed the strips flat and sanded off the lethally sharp edges.
It can be curved by heating over a flame and holding the bend until cool. That's best done a little at a time to avoid charring. Once cooled, it seems to hold the bend well.
The last time I had any, I spotted one of those patio light things, that had lost its' light, going cheap. That yielded about a dozen 20" ish lengths for an outlay of a couple of quid.

Pete
PETERRAKE is offline Find More Posts by PETERRAKE
Reply With Quote
Old Feb 04, 2012, 11:39 PM
Registered User
crawlspace's Avatar
Pacific Northwest
Joined Jan 2009
355 Posts
While I searched for suitable bamboo I bent and soldered all the landing gear wire and am now getting a clearer picture of what Pete had in mind for the detachable rigging. He placed wire hooks on the pylon and at the axle center to slip the rigging end loops on and off, I've shown a closeup of the one on the gear.

Pete,

I finally managed to find some bamboo and went about splitting and sanding it as described. My first attempt has yielded 3mm thick by 5mm wide strips which seems too small. The skids on the plans have a profile of 7mm (I'm assuming they're square) so do I need to keep searching for a piece large enough to have a wall that thick or do you think the pieces I have will do?

Mike
crawlspace is offline Find More Posts by crawlspace
Reply With Quote
Old Feb 05, 2012, 03:19 AM
Registered User
Norfolk, England
Joined Sep 2001
7,600 Posts
Mike,
Obviously bigger than that would be better - and stronger. How about pre-bending some strips and gluing them together to make 5x6 or 5x9 skids?
Although it may be a bit late, if you've planed and sanded all the strips, may be only planing the inside flat, making the bends over the widest direction and then joining them to form a sort of oval shape would work. It might even allow slightly wider strips to be used.

Pete
PETERRAKE is offline Find More Posts by PETERRAKE
Reply With Quote
Old Feb 11, 2012, 02:48 PM
Registered User
crawlspace's Avatar
Pacific Northwest
Joined Jan 2009
355 Posts
Quote:
Originally Posted by PETERRAKE View Post
Mike,
Obviously bigger than that would be better - and stronger. How about pre-bending some strips and gluing them together to make 5x6 or 5x9 skids?
Although it may be a bit late, if you've planed and sanded all the strips, may be only planing the inside flat, making the bends over the widest direction and then joining them to form a sort of oval shape would work. It might even allow slightly wider strips to be used.

Pete
Planed and sanded all the strips? I'm way too lazy for that, I only did a couple to start. I now have a couple pieces planed on the inside only that are 3-3.5x 11, they feel strong enough to do the job but I wanted to ask if that would be all right or if I should go ahead and rip them down and join them to make a 5x6 as you have suggested. The single wide strip more closely resembles a ski whereas the joined pieces would be more tubelike so I'm wondering about appearance as well as strength.

Mike
crawlspace is offline Find More Posts by crawlspace
Reply With Quote
Old Feb 11, 2012, 06:54 PM
Registered User
Norfolk, England
Joined Sep 2001
7,600 Posts
Mike,
I'd go for the thicker, narrower option. Either should be strong enough but, unless you can bend the strips along the wide dimension, they will resemble skis rather than skids.

Sorry to be a pain about this but I feel bamboo for the skids is essential. Others have tried laminated ply, or wood sheathed wire and the wood always breaks the first time the model ends up on its' nose. Now, if you can guarantee not to nose over..........

Pete

Pete
PETERRAKE is offline Find More Posts by PETERRAKE
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Build Log Peter Rake's 60" Pfalz E.1 - 3rd Prototype, yes another one... 1905Flyer3 Scale Kit/Scratch Built 40 Nov 30, 2011 02:04 AM
Build Log "The Rooster" Peter Rake's Samolot Kogutek | Prototype Build hoffboy Scale Kit/Scratch Built 91 Nov 21, 2011 02:10 AM
Build Log Peter Rake's 60" Pfalz E.1 - 2nd Prototype Newtron Scale Kit/Scratch Built 64 Oct 12, 2011 10:13 PM
Build Log Peter Rake's Macchi M16 - prototype build Redbaron25 Scale Kit/Scratch Built 82 Jan 25, 2011 05:27 AM
Build Log Peter Rake's Udet Flamingo Prototype Build uranus456 Scale Kit/Scratch Built 55 Dec 01, 2009 08:20 AM