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This is another item of lockdown distraction. Good brain exercise.
One way of controlling an indoor model is to use differential thrust and no control surfaces. This is most often done using brushed motors. Purpose built controllers for this form of control are relatively rare but there is an easier way.
Rifle around in your junk box for a "retired" quad with brushed motors. Mount the control board flat on the aircraft pointing forward. Then take the left hand motors and mount them pointing forward a little way out on the left wing but as close together as possible. Ditto for the left hand side motors.
Magically every thing except roll control will cancel out it seems.
If you use one motor from each side then you will get throttle up when you pitch down and vice versa when you pitch up. Sort of a rudimentary height hold.
As you see below the idea works with a retired Hubsan X4 controller.
You can see and hear the effect of corrections on the pitch axis where the planks are very sensitive. If you use a "Tiny Whoop" class brushed motor flight controller, running say Betaflight or iNav, you can tune the control gains easily while using only two motors.
Not too hard really
.
...Continue Reading
One way of controlling an indoor model is to use differential thrust and no control surfaces. This is most often done using brushed motors. Purpose built controllers for this form of control are relatively rare but there is an easier way.
Rifle around in your junk box for a "retired" quad with brushed motors. Mount the control board flat on the aircraft pointing forward. Then take the left hand motors and mount them pointing forward a little way out on the left wing but as close together as possible. Ditto for the left hand side motors.
Magically every thing except roll control will cancel out it seems.
If you use one motor from each side then you will get throttle up when you pitch down and vice versa when you pitch up. Sort of a rudimentary height hold.
As you see below the idea works with a retired Hubsan X4 controller.
You can see and hear the effect of corrections on the pitch axis where the planks are very sensitive. If you use a "Tiny Whoop" class brushed motor flight controller, running say Betaflight or iNav, you can tune the control gains easily while using only two motors.
Not too hard really
.| 20200826 Differential Thrust Steering Using "Retired" Micro Quad FCs Part 2 (0 min 41 sec) |
| 20200726 Differential Thrust Steering Using "Retired" Micro Quad FCs Part 1 (0 min 25 sec) |
Intended to be used as a fixed wing test platform for UAVXArm.
Bought on sale as a kit from Banggood but in hindsight could have bought a foam only kit for even less as I have plenty of carbon tubing
.
Used PVA for assembly but left wings unglued to make it a bit more portable. PVA tends to crack on high-speed crashes rather than tearing up the foam. PVA also tends to foam but can be contained using masking tape until it dries. Wings are fastened using woven fibreglass tape which lasts 1-2 seasons in our sunshine. In this case the tape has been fastened on the underside. Winglets are fastened using hot glue. Control horns are epoxied to the carbon rod in the elevons using a slightly oversized hole in the foam.
Motor is an AXN-2208-2150 which comes originally from an AXN Cloud and runs a 6x4.5" prop used on some of my multicopters. Current is around 19A and I am using a 30A Turnigy Plush ESC. Servos are HXT900 9gm and while I would have preferred MG one of the last two I had was DOA.
I am using a 1300 3s pack in the GoPro camera position which will give around 45min in still air with an AUW of 475gm. Predicted climb rate is around 9M/S. A 2200 3s pack fits in the main compartment but pushes the AUW to 560gm and only gives another 10 minutes of flight time. The VTX and camera roughly another 50gm.
CG set initially at 125mm as recommended but moved back to 135mm. This is just forward of the main spar currently but I will most likely go back to 140mm which is...Continue Reading
Bought on sale as a kit from Banggood but in hindsight could have bought a foam only kit for even less as I have plenty of carbon tubing
.Used PVA for assembly but left wings unglued to make it a bit more portable. PVA tends to crack on high-speed crashes rather than tearing up the foam. PVA also tends to foam but can be contained using masking tape until it dries. Wings are fastened using woven fibreglass tape which lasts 1-2 seasons in our sunshine. In this case the tape has been fastened on the underside. Winglets are fastened using hot glue. Control horns are epoxied to the carbon rod in the elevons using a slightly oversized hole in the foam.
Motor is an AXN-2208-2150 which comes originally from an AXN Cloud and runs a 6x4.5" prop used on some of my multicopters. Current is around 19A and I am using a 30A Turnigy Plush ESC. Servos are HXT900 9gm and while I would have preferred MG one of the last two I had was DOA.
I am using a 1300 3s pack in the GoPro camera position which will give around 45min in still air with an AUW of 475gm. Predicted climb rate is around 9M/S. A 2200 3s pack fits in the main compartment but pushes the AUW to 560gm and only gives another 10 minutes of flight time. The VTX and camera roughly another 50gm.
CG set initially at 125mm as recommended but moved back to 135mm. This is just forward of the main spar currently but I will most likely go back to 140mm which is...Continue Reading
Time to build a plank with a bit of "Wick" so this is a build of the 60" Zipper put with a PW51 airfoil . The Zipper was originally Birdworks way way back with an EH 2-10 airfoil but for more than a decade it has been available as a part kit from Off The Edge Sailplanes in Oz. Yes it is an old design but then not all new things are that good.
http://www.offtheedge.com.au/page.php?id=16
Mine will probably not be quite as pretty as that on the Edge page my first build being WBPU and a few layers of light glass cloth. I will add a thin strip of carbon plate as a spar to help out the somewhat thinner glass skin. Glenn aka "Zipper" offered to cut me a set of balsa elevons as well which I will sand to profile if required as I will see if the WBPU covered elevons prove stiff enough. I will most likely commit sacrilege and add a motor
. Sort of functioning ballast.
There are a number of build threads out there and the outline instructions are on the Edge pages:
http://www.offtheedge.com.au/page.php?id=29
http://home.earthlink.net/~jaffee/zipper.html
http://www.offtheedge.com.au/page.php?id=16
Mine will probably not be quite as pretty as that on the Edge page my first build being WBPU and a few layers of light glass cloth. I will add a thin strip of carbon plate as a spar to help out the somewhat thinner glass skin. Glenn aka "Zipper" offered to cut me a set of balsa elevons as well which I will sand to profile if required as I will see if the WBPU covered elevons prove stiff enough. I will most likely commit sacrilege and add a motor
. Sort of functioning ballast. There are a number of build threads out there and the outline instructions are on the Edge pages:
http://www.offtheedge.com.au/page.php?id=29
http://home.earthlink.net/~jaffee/zipper.html
I have a Dream Flight Weasel which has not had much flying mainly because the slope winds are not always kind.
http://dream-flight.com/products/weasel-trek
This proved to be the case recently and Ray mused "I wonder what it would take to add a motor?". He has a Weasel as well but he knew I would immediately take the plunge.
So I did a quick mod and added a BE1806-2300 with a plastic 5x3 prop borrowed from my 250 Racer spares along with a Turnigy 12A ESC and 1000mAH pack. The weight has increased by a shocking 15gm
. Others, of course, have also done similar conversions if you search them down.
The static thrust of the motor/prop combination is 390gm just slightly above the AUW of 380gm so vertical is possible. Pack is good for around 15 minutes at full throttle and an hour at cruise. Air to the ESC behind the battery could be improved by removing top hatch or putting a tunnel through to the launch finger hole?
The changes to the fuselage are straightforward with the removal of the rear wall of the original battery box and a ply firewall braced backwards with triangular ply doublers - the foam is too squishy.
I could have just cut the nose off and end glued the firewall but I wanted to preserve the lines reasonably well. I used WeldBond white glue which takes a while to dry but is slightly flexible and adheres to the foam quite well.
Test flight confirms performance and certainly easily vertical. Two longish flights and only 270mAH from the pack. A rather bleak damp day but caught some thermals as well - surprising
.
http://dream-flight.com/products/weasel-trek
This proved to be the case recently and Ray mused "I wonder what it would take to add a motor?". He has a Weasel as well but he knew I would immediately take the plunge
.So I did a quick mod and added a BE1806-2300 with a plastic 5x3 prop borrowed from my 250 Racer spares along with a Turnigy 12A ESC and 1000mAH pack. The weight has increased by a shocking 15gm
. Others, of course, have also done similar conversions if you search them down.The static thrust of the motor/prop combination is 390gm just slightly above the AUW of 380gm so vertical is possible. Pack is good for around 15 minutes at full throttle and an hour at cruise. Air to the ESC behind the battery could be improved by removing top hatch or putting a tunnel through to the launch finger hole?
The changes to the fuselage are straightforward with the removal of the rear wall of the original battery box and a ply firewall braced backwards with triangular ply doublers - the foam is too squishy.
I could have just cut the nose off and end glued the firewall but I wanted to preserve the lines reasonably well. I used WeldBond white glue which takes a while to dry but is slightly flexible and adheres to the foam quite well.
Test flight confirms performance and certainly easily vertical. Two longish flights and only 270mAH from the pack. A rather bleak damp day but caught some thermals as well - surprising
.
I thought it was time to try a "pure" flying with no vertical surfaces. This was partially inspired by Karl Heinz's YB49 scale build.
https://www.rcgroups.com/forums/show....php?t=2634086
As far as I can tell the XB had the contra rotating props and the YB had the simple pusher prop configuration at considerable loss in performance. I don't fancy buying four of the HK contra rotating drives so YB-35 it is.
The airfoils for the X/YB-35/49 were NACA 65,3-019 at the root and 65,3-018 at the tip. These are quite thick and draggy and close to symmetrical requiring up trim in practice. Their low Re performance is not good at model scales. So in my case I will deviate a little and probably use MHxx cores at around 9% as I don't have the task of squeezing EDFs into the wing as would be the case with a YB-49 . I intend using elevons only, mixing rudder in as elevon differential and possibly thrust vectoring on the outer motors for yaw control.
Scaled roughly 1:20 to 2.4M span to cut from a 1.2M wide foam slab which is manageable. I will probably borrow the 4 ancient Turnigy 2213/20 motors with 3 blade 8x6 props from my Lancaster. With the 3S 4900mAh pack it should have an AUW of around 2.0Kg.
I could also raid the Lancaster's retracts in which case AUW would be around 2.5Kg. Initially it will be minimalist and hand launched.
WingCalc wing plans:
http://j.mp/29Sjep4 YB-35
http://j.mp/2aubLNd Using MH62 cores to hand
MotoCalc gives stall at 6M/S and 8M/S at 43% throttle for cruise. This is roughly scale AS if my comps are correct. Endurance at cruise is around 45min and ROC 4 m/S.
eCalc also suggests climb rate and endurance should by OK even if not vertical which was also the case for the original.
https://www.rcgroups.com/forums/show....php?t=2634086
As far as I can tell the XB had the contra rotating props and the YB had the simple pusher prop configuration at considerable loss in performance. I don't fancy buying four of the HK contra rotating drives so YB-35 it is.
The airfoils for the X/YB-35/49 were NACA 65,3-019 at the root and 65,3-018 at the tip. These are quite thick and draggy and close to symmetrical requiring up trim in practice. Their low Re performance is not good at model scales
. So in my case I will deviate a little and probably use MHxx cores at around 9% as I don't have the task of squeezing EDFs into the wing as would be the case with a YB-49 . I intend using elevons only, mixing rudder in as elevon differential and possibly thrust vectoring on the outer motors for yaw control. Scaled roughly 1:20 to 2.4M span to cut from a 1.2M wide foam slab which is manageable. I will probably borrow the 4 ancient Turnigy 2213/20 motors with 3 blade 8x6 props from my Lancaster. With the 3S 4900mAh pack it should have an AUW of around 2.0Kg.
I could also raid the Lancaster's retracts in which case AUW would be around 2.5Kg. Initially it will be minimalist and hand launched
. WingCalc wing plans:
http://j.mp/29Sjep4 YB-35
http://j.mp/2aubLNd Using MH62 cores to hand
MotoCalc gives stall at 6M/S and 8M/S at 43% throttle for cruise. This is roughly scale AS if my comps are correct. Endurance at cruise is around 45min and ROC 4 m/S.
eCalc also suggests climb rate and endurance should by OK even if not vertical which was also the case for the original.
I could not find any plans but this NASA Delta Wing seems to be based on an idea from a NASA schools project to teach basic aerodynamics.
https://www.nasa.gov/pdf/205703main_...ing_Glider.pdf
From what I can see on the video it uses a KFm2 foil but so far I have not found any other details so my dimensions are all guess work.
The video shows twin fins to clear the prop slot. Mine also has twin fins (because it looks good) but with a tractor prop and no slot (because it will fly better - probably).
Initial glide tests are promising. Foam is ColorBoard from Diaso as for the Arado build. Electronics are from a WLToys PoleCat (F939) for now.
CG position calculated using WingCGCalc. Latest wing plan used is HERE. Elevons are 30mm at the root tapering to 20mm. CG 108mm from cutoff LE for twin vertical stabiliser version flies OK.
Modified version has original vertical stabilisers simply moved out to form winglets which give some dihedral and the CG moves to 114mm. The winglets are set at 45 deg.
Summary: OK once I added a bit of washout to the winglets but not all that fun to fly as it requires continuous control input. Retired.
https://www.nasa.gov/pdf/205703main_...ing_Glider.pdf
From what I can see on the video it uses a KFm2 foil but so far I have not found any other details so my dimensions are all guess work.
| RC Depron Delta Nasa Glider Indoor Flight Faszination Modellbau 2014 *60fpsHD* (2 min 18 sec) |
The video shows twin fins to clear the prop slot. Mine also has twin fins (because it looks good) but with a tractor prop and no slot (because it will fly better - probably
). Initial glide tests are promising. Foam is ColorBoard from Diaso as for the Arado build. Electronics are from a WLToys PoleCat (F939) for now.
CG position calculated using WingCGCalc. Latest wing plan used is HERE. Elevons are 30mm at the root tapering to 20mm. CG 108mm from cutoff LE for twin vertical stabiliser version flies OK.
Modified version has original vertical stabilisers simply moved out to form winglets which give some dihedral and the CG moves to 114mm. The winglets are set at 45 deg.
Summary: OK once I added a bit of washout to the winglets but not all that fun to fly as it requires continuous control input
. Retired.
