Cute clothespin.
Jugs!!!
- Thread starter willsonman
- Start date
Spent an hour (ok, it was really like 2) figuring out how to setup the delay I wanted. A couple of ways to do it but using a 3-position switch, one way is the best. Keep in mind that this one switch is controlling the pneumatic landing gear, a mechanical tail retract, tail gear doors, and the inner gear doors on the wing. All have to be timed perfectly and at a speed that realistic. Now, should I decide to get CRAZY, I could add another pneumatic valve and use two channels for the landing gear and stagger them. Jugs were beat up a lot and prone to some pretty good patch jobs. I can see the hydraulic system being one of those things. I'm still hopeful to get an airspeed indicator to warn me of stalls on landing.
*SIGH!* all hopeful wishes on an already portly airframe. Details add weight and that is where the manic OCD meets the logical scientist.
Been awhile since I updated here. At FTFF there was a killer deal on some 4S 6600 batteries. Got 2 for $15. Apparently folks have had issues with bad cells. Mine tested fine and even had pretty similar cell internal resistance. With the power system robbed for the P-6E I then took the power system from my AT-6 Texan and put it in this. I think it will be more appropriate anyway. 1300W on a 9 pound airplane makes for some pretty realistic flying. Still need to make sure everything is tight but its going well.
Last night I managed to get the tail gear doors situated... FINALLY! Guitar string (0.250mm) used to make a spring. Picked up a technique from John Morgan (my favorite RCG Builder) that you put some heat shrink on the wire and use that with CA. The he shrink really likes the CA and makes installing the spring a breeze. Also takes paint well.
So now I need to re-evaluate the CG and battery box. The new batteries fit, but only one at a time. That's fine as the 6600s should give me ample flying time. 4500s got be about 7 minutes on the Texan. I'm sure I will need ballast using just one battery. I need to put it all together and figure it out.
Last night I managed to get the tail gear doors situated... FINALLY! Guitar string (0.250mm) used to make a spring. Picked up a technique from John Morgan (my favorite RCG Builder) that you put some heat shrink on the wire and use that with CA. The he shrink really likes the CA and makes installing the spring a breeze. Also takes paint well.
So now I need to re-evaluate the CG and battery box. The new batteries fit, but only one at a time. That's fine as the 6600s should give me ample flying time. 4500s got be about 7 minutes on the Texan. I'm sure I will need ballast using just one battery. I need to put it all together and figure it out.
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Nice. I'll like the spring loaded doors. I assume you would store with the doors open or risk losing the springy-ness? I haven't tried this method before, but I'll be rebuilding the tailwheel doors on the P-40 in the coming months and would like to lose the servo mechanism.
Yes, stored with the gear down. There is a bit of slack in the elastic cord that pulls the doors closed. Keeping the doors opened keeps that slack off a load and lets the spring sit in a more natural position.
Some setups prefer that the gear be pushed out and the doors are sprung closed. I do not prefer this as if there is a minor failure it has potential to create a safety concern. Binding of the tail gear in the wrong direction means the airplane could veer off once on the ground and hit someone. This is just my opinion and approach. Others would argue that you get better door closure. I'm all for details like that but not really at the expense of someone getting hurt.
I plan to take this same approach with the main gear doors... when I get there. I'll use polystyrene tubing to create an arm that the main wheels will physically touch and close the doors. The doors will be sprung open so that if there is a failure with the door system I can get the mains down with less restriction. These are also spring air retracts. So if the system loses pressure the gear automatically springs down. If I had those doors on a servo they would be holding the gear up and draw a lot of current... possibly overloading my BEC. Not safe.
Some setups prefer that the gear be pushed out and the doors are sprung closed. I do not prefer this as if there is a minor failure it has potential to create a safety concern. Binding of the tail gear in the wrong direction means the airplane could veer off once on the ground and hit someone. This is just my opinion and approach. Others would argue that you get better door closure. I'm all for details like that but not really at the expense of someone getting hurt.
I plan to take this same approach with the main gear doors... when I get there. I'll use polystyrene tubing to create an arm that the main wheels will physically touch and close the doors. The doors will be sprung open so that if there is a failure with the door system I can get the mains down with less restriction. These are also spring air retracts. So if the system loses pressure the gear automatically springs down. If I had those doors on a servo they would be holding the gear up and draw a lot of current... possibly overloading my BEC. Not safe.
I got all the motor mount stuff tightened and had to re-program the ESC. The Suppo does not auto-detect the cell count. Also got the motor turning in the right direction.
I dont think I had posted the cuts I made in the fuselage for venting. On big electrics you really need to make sure things stay cool so I grabbed a quick shot of the rear exit holes.
I moved onto the battery area. I removed one ply plate and I will rig up some velcro to keep things secure. With both of the batteries in this location the CG is pretty much dead on per the assembly instructions (128mm from LE).
Next, I needed a way to connect both of these batteries to the the airplane. an adapter was made using two XT60 connectors and 4.5mm bullet plugs. I put the two XT60s together with CA. Then I soldered each bullet across the two + and - terminals. This way I am in parallel with the two packs. So, now I have a 13.2Ah 4S battery. According to eCalc this translates to a minimum flight time at WOT of just over 10 minutes.
I have a 15x10 APC-E prop that I will try to fly on next but the plan is to replace it with a Xoar PJN prop. I tested the air system and did have a leak... actually a blowout. Pressured up to 100psi and one joint blew up. Fixed that and everything held fine. I got 14 cycles of the gear from 100psi to 60psi. Pressure up to 90psi will be fine for flight.
I dont think I had posted the cuts I made in the fuselage for venting. On big electrics you really need to make sure things stay cool so I grabbed a quick shot of the rear exit holes.
I moved onto the battery area. I removed one ply plate and I will rig up some velcro to keep things secure. With both of the batteries in this location the CG is pretty much dead on per the assembly instructions (128mm from LE).
Next, I needed a way to connect both of these batteries to the the airplane. an adapter was made using two XT60 connectors and 4.5mm bullet plugs. I put the two XT60s together with CA. Then I soldered each bullet across the two + and - terminals. This way I am in parallel with the two packs. So, now I have a 13.2Ah 4S battery. According to eCalc this translates to a minimum flight time at WOT of just over 10 minutes.
I have a 15x10 APC-E prop that I will try to fly on next but the plan is to replace it with a Xoar PJN prop. I tested the air system and did have a leak... actually a blowout. Pressured up to 100psi and one joint blew up. Fixed that and everything held fine. I got 14 cycles of the gear from 100psi to 60psi. Pressure up to 90psi will be fine for flight.
Well, its been awhile since an update here. I've had the Jug in the air 3 times on this new setup and its quite nice. The back-torque is better with the different motor. I've ordered the Xoar prop to replace the APC-E. Each time up I've gotten in about 8 minutes of flying time. Motor comes down hot but I believe that is due to the prop. We'll see when the new one comes in. I've not been able to stick the landing just yet so the cowl is getting a bit beat up. When I make the FG repairs I'll add some CF tow to the inner lip to make it super strong for future mishaps. The tail gear doors are holding up well and functioning perfectly. The grass does need to be freshly cut for the best tracking.
On the 2nd flight I tried reducing the throw of the flaps, as full-flap is nearly 90 degrees. Totally not needed. I reduced to around 40 degrees using a curve in my Taranis. Then, when I used them on this flight, she still ballooned heavily. I do have Flap-elevator mixing going on so I looked things over once the shaking legs quit. I then realized that my mix was backwards for the mix. Elevator should go DOWN when the flaps go down. Rookie mistake.:black_eyed:
Third flight the take-off was stellar with just a touch of flap. Landing was better but there was far too much elevator mixed in. I backed that off by 50% and we will see how that works.
I'm hopeful to get the mix right so I can slow her down better for landings on my short runway. This model flies very scale so she does not slow down all that much when the power is reduced. The nose just drops. As it should be but the need for the proper mix is there.
On the 2nd flight I tried reducing the throw of the flaps, as full-flap is nearly 90 degrees. Totally not needed. I reduced to around 40 degrees using a curve in my Taranis. Then, when I used them on this flight, she still ballooned heavily. I do have Flap-elevator mixing going on so I looked things over once the shaking legs quit. I then realized that my mix was backwards for the mix. Elevator should go DOWN when the flaps go down. Rookie mistake.:black_eyed:
Third flight the take-off was stellar with just a touch of flap. Landing was better but there was far too much elevator mixed in. I backed that off by 50% and we will see how that works.
I'm hopeful to get the mix right so I can slow her down better for landings on my short runway. This model flies very scale so she does not slow down all that much when the power is reduced. The nose just drops. As it should be but the need for the proper mix is there.
Ok fellas, I've done some prop testing so lets break things down to put the nail in the coffin for APC-E propellers.
Setup:
NTM PropDrive 42-48 650Kv (Max 1300W)
Suppo 70A ESC
ReadyMade RC 6600mAh 4S (fully charged)
Props Size Mass Cost Thrust Power
APC-E 15x10 48g $6.39 72oz. 930W
Xoar 15x10 30g $13.99 92oz. 1047W
Lets do some math... Performance = oz. of thrust / watt
APC-E = 0.08
Xoar = 0.09
Apples to Apples
Using that number, and assuming that the power is applied linearly (maybe, maybe not), if the power on the Xoar is reduced to 930W to Match the APC-E prop we come in at 81.7oz for the Xoar vs. 72 for the APC-E.
Other Factors:
The APC-E props are notoriously known for their excessive flex on full-power. This will reduce its efficiency by not providing even thrust and increasing the load on the motor. The Xoar, being made of beechwood, will not do this. This means that the throttle curve is more likely to be linear, as assumed above.
The other factor is the airfoil cross-section of the prop blades. Since the Xoar is more semi-symmetrical the power will unload more in the air. The APC-E is under-cambered, so it will unload some, but not to the extent that the Xoar will. This is simple physics of DRAG. It is well-known, even in our hobby, that under-cambered creates a lot of lift but consequently a lot of drag. Flat-bottom or semi-symmetrical is known to be the compromise here where the drag is dramatically decreased while creating substantial lift, but not as much as under-cambered.
Cost:
So, thrust per dollar clearly goes to the APC team here but you sacrifice the efficiency. Not to mention the look. Xoar props also come balanced from the factory, have a smoother finish (reducing drag), and are just plain more visually appealing IMO.
Setup:
NTM PropDrive 42-48 650Kv (Max 1300W)
Suppo 70A ESC
ReadyMade RC 6600mAh 4S (fully charged)
Props Size Mass Cost Thrust Power
APC-E 15x10 48g $6.39 72oz. 930W
Xoar 15x10 30g $13.99 92oz. 1047W
Lets do some math... Performance = oz. of thrust / watt
APC-E = 0.08
Xoar = 0.09
Apples to Apples
Using that number, and assuming that the power is applied linearly (maybe, maybe not), if the power on the Xoar is reduced to 930W to Match the APC-E prop we come in at 81.7oz for the Xoar vs. 72 for the APC-E.
Other Factors:
The APC-E props are notoriously known for their excessive flex on full-power. This will reduce its efficiency by not providing even thrust and increasing the load on the motor. The Xoar, being made of beechwood, will not do this. This means that the throttle curve is more likely to be linear, as assumed above.
The other factor is the airfoil cross-section of the prop blades. Since the Xoar is more semi-symmetrical the power will unload more in the air. The APC-E is under-cambered, so it will unload some, but not to the extent that the Xoar will. This is simple physics of DRAG. It is well-known, even in our hobby, that under-cambered creates a lot of lift but consequently a lot of drag. Flat-bottom or semi-symmetrical is known to be the compromise here where the drag is dramatically decreased while creating substantial lift, but not as much as under-cambered.
Cost:
So, thrust per dollar clearly goes to the APC team here but you sacrifice the efficiency. Not to mention the look. Xoar props also come balanced from the factory, have a smoother finish (reducing drag), and are just plain more visually appealing IMO.
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