Design & build of Pencam-class photo platform - Page 2

Karl B² · Jun 26, 2003, 06:02 PM

Hey Dennis, I'll keep the flying in mind, though Madison is a 4 hour hike for me. Are you planning on attending the MARCEE meet in St. Paul this weekend?

I was going to use simple pull-pull bellcranks, but ended up going with a pulley/drum system. Only destroyed 2 meters of kevlar thread trying to find the best methods to route it through the boom and guide tubes

, but I got over that learning curve with plenty of thread to spare.

The pulleys on the surfaces are made of 1/32" ply. I chucked it in my Dremel and used a 150 grit block to turn it down. For the servos I'll make more of a drum than a pulley. The rudder drum will match the pulley for a 1:1 angular action. The elevator drum will be smaller by about a third for reduced throw.

Karl

Bottom view:

Karl B² · Jun 26, 2003, 06:05 PM

Side shot shows the pulley offset required by the reclining hinge line:

Karl B² · Jun 28, 2003, 10:33 AM

Look ma, no servo! Well, at least not attached to the camera anymore. Wired RadioShack # 275-016A switches parallel to the shutter & mode switches. Left stick triggers the shutter, right triggers the mode switch. Also wired a USB --> BEC plug, coming out of the battery cover, not visible in this shot.

Without the servo piggy-backing on the camera case, there will be room for it to rotate within the fuselage. I mounted the ball links more centrally on the ends of the camera.

Karl

KeithLuneau · Jun 28, 2003, 01:42 PM

Wouldn't a smaller pulley on the elevator give it more throw?

Karl B² · Jun 28, 2003, 02:25 PM

Yes, the smaller the driven (surface) pulley, the greater the surface throw. If the driven pulley is the same size as the drive (servo) pulley, the surface angular deflection will equal the output shaft angular deflection.

My Hitec HS-55's give about +/- 45 degrees. I'm targeting +/- 30 degrees rudder throw, and about +/- 15 degrees for elevator. The elevator drive will actually have to be about 1/3 the diameter of the driven, and the rudder drive will be about 75% the diameter of the driven.

The pulley system, as opposed to a standard pushrod/bellcrank, has no built in limits. The only mechanical limits on surface throw are the angles I sanded into the LE for hinging. The elevator will move +/- 30, and the rudder will move about +/- 45 degrees max. I'm setting the pulley sizes for just under these limits, and can always back off the ATV if this proves too sensitive.

Pros of this control setup: extremely light (good for long runs), virtually no slop, less possibility of binding than pull-pull bellcranks, true linear output with a non-computer radio, can follow more torturous path than pushrods by using idler pulleys and/or guide tubes.

Cons: more work to rig, can't be easily retrofitted due to interference issues between the pulley and the fixed surface, mechanical adjustment of throw requires a pulley change.

I've always been meaning to try it and the time was now. Like changing brake pads on a car, the first time takes the longest.

Karl B² · Jun 29, 2003, 11:04 PM

Got the camera mounted this weekend. Ball studs on the camera ends snap into nylon ball sockets. The sockets are attached to 1/2" threaded shafts, in turn attached to lengths of Sullivan nyrod buried in balsa stand-offs.

This shot shows the fuse bottom. The landing gear hardpoint will extend forward a few inches from the crossbrace over the camera. The bottom from there forward will be a removeable hatch.

Karl

Karl B² · Jun 29, 2003, 11:08 PM

View looking up at the bottom, facing the rear. Front cam mount and USB --> BEC cable exiting through the battery hatch are visible. The USB port will be accessible through the forward bottom hatch.

Karl B² · Jun 29, 2003, 11:14 PM

Looking up at the rear camera mount. Test photos of several angles assure that none of the fuse is visible. Camera has clearance to rotate 360 degrees on the ball mounts. The lower rear corner of the fuse behind the camera will be enclosed with either a built-up balsa or balsa-framed sheet ABS removeable cowl.

Karl B² · Jul 02, 2003, 06:27 PM

Landing gear is a one-piece 3/32" wire. To clear the camera, it follows the fuse sides then crosses above the camera.

The built-up balsa front hatch was fabricated once the gear was in place.

Karl B² · Jul 02, 2003, 06:30 PM

My wing-taster buddy is visible in the background of the previous shot.

The motor is back in my Slowstick for an early July 4th getaway. Hope to find some golf courses and try out my polarizer-equipped Aiptek. Be back Friday!

Karl

KeithLuneau · Jul 02, 2003, 07:21 PM

Lookin' good. How much right thrust is in the fuse? It should work out ok, after you get to altitude and shot the motor off, hopefully very little trim changed will be needed. It's hard to trim a plane that's 1000+ feet in the air. LOL

Karl B² · Jul 02, 2003, 08:06 PM

I have 3* down and 4* right. The prop shaft is centered where it comes through the front former, so there's a lot of gearbox & motor angled left of center.

I'm already working on my 'magazine' type flight review: "climbs with authority, no trim needed!"

Karl

eBird · Jul 02, 2003, 09:02 PM

Quote:

Originally posted by Kinnic^2
I have 3* down and 4* right. The prop shaft is centered where it comes through the front former, so there's a lot of gearbox & motor angled left of center.

I'm already working on my 'magazine' type flight review: "climbs with authority, no trim needed!"

Karl

Karl, here's a semi useless tip of the day:
For the "degree" sign, hold down ALT and press 2 4 8 on the numeric keypad. 3° 4°

KeithLuneau · Jul 02, 2003, 09:08 PM

Cool, where can I find some more codes like that? I'm assuming they are ascii codes?

EDIT - nevermind, http://www.asciitable.com/

RMihara · Jul 02, 2003, 10:04 PM

You could just fire up 'Charmap.exe' (Start-Programs-Accesories).

Click on the character you want and look for the 'Alt' code in the lower right corner

Roger

Jun 26, 2003, 06:02 PM	#16
Karl B² half fast Join Date: Jan 2003 Location: Western Wisconsin, USA Posts: 4,258	Hey Dennis, I'll keep the flying in mind, though Madison is a 4 hour hike for me. Are you planning on attending the MARCEE meet in St. Paul this weekend? I was going to use simple pull-pull bellcranks, but ended up going with a pulley/drum system. Only destroyed 2 meters of kevlar thread trying to find the best methods to route it through the boom and guide tubes , but I got over that learning curve with plenty of thread to spare. The pulleys on the surfaces are made of 1/32" ply. I chucked it in my Dremel and used a 150 grit block to turn it down. For the servos I'll make more of a drum than a pulley. The rudder drum will match the pulley for a 1:1 angular action. The elevator drum will be smaller by about a third for reduced throw. Karl Bottom view: Attached Thumbnails 48.0 KB · Views: 539

Jun 26, 2003, 06:05 PM	#17
Karl B² half fast Join Date: Jan 2003 Location: Western Wisconsin, USA Posts: 4,258	Side shot shows the pulley offset required by the reclining hinge line: Attached Thumbnails 45.6 KB · Views: 543

Jun 28, 2003, 10:33 AM	#18
Karl B² half fast Join Date: Jan 2003 Location: Western Wisconsin, USA Posts: 4,258	Look ma, no servo! Well, at least not attached to the camera anymore. Wired RadioShack # 275-016A switches parallel to the shutter & mode switches. Left stick triggers the shutter, right triggers the mode switch. Also wired a USB --> BEC plug, coming out of the battery cover, not visible in this shot. Without the servo piggy-backing on the camera case, there will be room for it to rotate within the fuselage. I mounted the ball links more centrally on the ends of the camera. Karl Attached Thumbnails 48.7 KB · Views: 496

Jun 29, 2003, 11:04 PM	#21
Karl B² half fast Join Date: Jan 2003 Location: Western Wisconsin, USA Posts: 4,258	Weekend Progress Got the camera mounted this weekend. Ball studs on the camera ends snap into nylon ball sockets. The sockets are attached to 1/2" threaded shafts, in turn attached to lengths of Sullivan nyrod buried in balsa stand-offs. This shot shows the fuse bottom. The landing gear hardpoint will extend forward a few inches from the crossbrace over the camera. The bottom from there forward will be a removeable hatch. Karl Attached Thumbnails 27.4 KB · Views: 456

Jun 29, 2003, 11:08 PM	#22
Karl B² half fast Join Date: Jan 2003 Location: Western Wisconsin, USA Posts: 4,258	View looking up at the bottom, facing the rear. Front cam mount and USB --> BEC cable exiting through the battery hatch are visible. The USB port will be accessible through the forward bottom hatch. Attached Thumbnails 35.2 KB · Views: 438

Jun 28, 2003, 01:42 PM	#19
KeithLuneau Live FPV FTW?! ;) Join Date: Jan 2002 Location: Central Louisiana Posts: 2,400	Wouldn't a smaller pulley on the elevator give it more throw?

Jun 28, 2003, 02:25 PM	#20
Karl B² half fast Join Date: Jan 2003 Location: Western Wisconsin, USA Posts: 4,258	Yes, the smaller the driven (surface) pulley, the greater the surface throw. If the driven pulley is the same size as the drive (servo) pulley, the surface angular deflection will equal the output shaft angular deflection. My Hitec HS-55's give about +/- 45 degrees. I'm targeting +/- 30 degrees rudder throw, and about +/- 15 degrees for elevator. The elevator drive will actually have to be about 1/3 the diameter of the driven, and the rudder drive will be about 75% the diameter of the driven. The pulley system, as opposed to a standard pushrod/bellcrank, has no built in limits. The only mechanical limits on surface throw are the angles I sanded into the LE for hinging. The elevator will move +/- 30, and the rudder will move about +/- 45 degrees max. I'm setting the pulley sizes for just under these limits, and can always back off the ATV if this proves too sensitive. Pros of this control setup: extremely light (good for long runs), virtually no slop, less possibility of binding than pull-pull bellcranks, true linear output with a non-computer radio, can follow more torturous path than pushrods by using idler pulleys and/or guide tubes. Cons: more work to rig, can't be easily retrofitted due to interference issues between the pulley and the fixed surface, mechanical adjustment of throw requires a pulley change. I've always been meaning to try it and the time was now. Like changing brake pads on a car, the first time takes the longest.

Jun 29, 2003, 11:14 PM	#23
Karl B² half fast Join Date: Jan 2003 Location: Western Wisconsin, USA Posts: 4,258	Last One Tonight Looking up at the rear camera mount. Test photos of several angles assure that none of the fuse is visible. Camera has clearance to rotate 360 degrees on the ball mounts. The lower rear corner of the fuse behind the camera will be enclosed with either a built-up balsa or balsa-framed sheet ABS removeable cowl. Attached Thumbnails 38.1 KB · Views: 450

Jul 02, 2003, 06:27 PM	#24
Karl B² half fast Join Date: Jan 2003 Location: Western Wisconsin, USA Posts: 4,258	Front Hatch, LG Landing gear is a one-piece 3/32" wire. To clear the camera, it follows the fuse sides then crosses above the camera. The built-up balsa front hatch was fabricated once the gear was in place. Attached Thumbnails 32.4 KB · Views: 373

Jul 02, 2003, 06:30 PM	#25
Karl B² half fast Join Date: Jan 2003 Location: Western Wisconsin, USA Posts: 4,258	hatch shown in place My wing-taster buddy is visible in the background of the previous shot. The motor is back in my Slowstick for an early July 4th getaway. Hope to find some golf courses and try out my polarizer-equipped Aiptek. Be back Friday! Karl Attached Thumbnails 25.4 KB · Views: 366

Jul 02, 2003, 07:21 PM	#26
KeithLuneau Live FPV FTW?! ;) Join Date: Jan 2002 Location: Central Louisiana Posts: 2,400	Lookin' good. How much right thrust is in the fuse? It should work out ok, after you get to altitude and shot the motor off, hopefully very little trim changed will be needed. It's hard to trim a plane that's 1000+ feet in the air. LOL

Jul 02, 2003, 08:06 PM	#27
Karl B² half fast Join Date: Jan 2003 Location: Western Wisconsin, USA Posts: 4,258	I have 3* down and 4* right. The prop shaft is centered where it comes through the front former, so there's a lot of gearbox & motor angled left of center. I'm already working on my 'magazine' type flight review: "climbs with authority, no trim needed!" Karl

Jul 02, 2003, 09:08 PM	#29
KeithLuneau Live FPV FTW?! ;) Join Date: Jan 2002 Location: Central Louisiana Posts: 2,400	Cool, where can I find some more codes like that? I'm assuming they are ascii codes? EDIT - nevermind, http://www.asciitable.com/ Last edited by KeithLuneau; Jul 02, 2003 at 09:18 PM.

Jul 02, 2003, 10:04 PM	#30
RMihara Aerial Shutterbug Join Date: Nov 2001 Location: San Mateo, California, United States Posts: 4,912	You could just fire up 'Charmap.exe' (Start-Programs-Accesories). Click on the character you want and look for the 'Alt' code in the lower right corner Roger

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