Thanks for your info, not sure how I came in heavier, I've got lead right in the nose cone to balance so I'm not sure what I could do to reduce the weight
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Mini Q
- Thread starter Glenn Beer
- Start date
Great info than thanks. When the conditions are right I'll try the coin method. I know it could be a personal thing but this is the first model that I have built that does not have an accurate cg measurement in the manual. Like you say depending on where exactly you measure from at the root could make a difference to the cg. I'm at exactly 22mm back measured from 15mm along from the fuse sides at the moment
I'm completing my mini-Q build, and I wanted to verify my CG and ballast plan with everyone. Though this is my first post, I've read this thread many times to determine the longitudinal CG and control surface throws. The ship currently weighs 254g with all of the gear/tail/canopy/servo covers/nosecone installed, and no ballast. I marked the 22mm CG location with tape and sharpie marker, and after loosely placing the Rx (FrSky RX4R) and LiPo battery (DualSky RXB08001) as far forward as practical, my CG is about 38mm behind (toward the tail) the 22mm mark.
After taping ballast to the midspan of the nosecone, I found it will take about 60 grams of ballast (about %25 of the aircraft weight) to move the CG forward to the 22mm mark, bringing the gross weight to 314g. Does this sound correct?
Also, should I be cool with the added weight, because it puts the glider at the optimal performance weight? Or, restating the question, was the CG purposely designed to allow for both powered and un-powered flight; the latter being a fast, heavy glider with a nosecone full of lead?
After taping ballast to the midspan of the nosecone, I found it will take about 60 grams of ballast (about %25 of the aircraft weight) to move the CG forward to the 22mm mark, bringing the gross weight to 314g. Does this sound correct?
Also, should I be cool with the added weight, because it puts the glider at the optimal performance weight? Or, restating the question, was the CG purposely designed to allow for both powered and un-powered flight; the latter being a fast, heavy glider with a nosecone full of lead?
I was setting up the servo throws tonight, and the right elevon servo (EMAX ES9051, on channel 3) was getting very hot and glitchy. I swapped in a new servo, but now the RX4R won't drive it on the same channel (3). The left elevon on channel 2 works fine, and if I put the new servo on channel 2, it works. I also tried channels 1 and four, and they seem hit and miss. Did the RX4R burn up?
Konrad
Very Strong User
This is the servo? https://alofthobbies.com/emax-es-9051.html
It is far too small for this plane.
Check your pin call out. It is not likely that you damaged the RX burning up the servo on ch3, if the other servos are still working. They share a common bus bar electrical architecture.
It is far too small for this plane.
Check your pin call out. It is not likely that you damaged the RX burning up the servo on ch3, if the other servos are still working. They share a common bus bar electrical architecture.
I was able to move the servos to channels 1 and 4, and they seem to work fine now. Though I believe channels 2 and 3 are toast. I haven't measured the output voltage, as I'm assuming the Rx is sending the servo the correct (?!) voltage by default. Can the PWM voltage be adjusted with this Rx?
I was also having trouble getting the canopy lid to fit cleanly onto the canopy recess. After examining the underside of the canopy lid, I discovered that the glass/carbon reinforcement, which secures the carbon rods at each end, extends into the area where the canopy lid sits on top of the canopy brace, causing the front and back of the canopy lid to lift when secured.
I sanded down the back edges of the rod reinforcement areas, removing both glass/carbon and large globs of epoxy. There were also high spots under the perimeter of the lid that needed to be knocked down for the lid to fit. You can see an area at the top left of the underside of the canopy lid where a resin rich spot was leveled.
I also had to sand the outer perimeter edge of the canopy lid in some areas to size it to the recess in the canopy.
The second photo shows how the canopy lid fits after sanding down the interference areas and high spots. Initially, there was a 1/16" air gap at the front and back of the canopy, and also edge overhang on the side and back (perimeter edges of the lid jumping over and past the canopy recess). Now the lid fits very tight and clean.
The nosecone is way undersized where it is supposed to fit into the nose of the glider, and I'm not sure how to make it fit right. I filled it with 60 grams of 00 buckshot and hot glue today to bring the CG in, and now the nosecone fit mismatch is even more of a problem. Any suggestions?
I sanded down the back edges of the rod reinforcement areas, removing both glass/carbon and large globs of epoxy. There were also high spots under the perimeter of the lid that needed to be knocked down for the lid to fit. You can see an area at the top left of the underside of the canopy lid where a resin rich spot was leveled.
I also had to sand the outer perimeter edge of the canopy lid in some areas to size it to the recess in the canopy.
The second photo shows how the canopy lid fits after sanding down the interference areas and high spots. Initially, there was a 1/16" air gap at the front and back of the canopy, and also edge overhang on the side and back (perimeter edges of the lid jumping over and past the canopy recess). Now the lid fits very tight and clean.
The nosecone is way undersized where it is supposed to fit into the nose of the glider, and I'm not sure how to make it fit right. I filled it with 60 grams of 00 buckshot and hot glue today to bring the CG in, and now the nosecone fit mismatch is even more of a problem. Any suggestions?
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Konrad
Very Strong User
I knew this was going to be a problem. Looks like you got it fitting well.
forum.alofthobbies.com
As to the nose I'd mix up any clear epoxy with white micro balloons and make a nice fillet. The color shouldn't be too far off, you might be able to adjust for it depending on the amount of micro balloons you use.
As the PWM voltage, few RX have voltage regulator or even one you can adjust. Most RX electrical bus bars are running the battery voltage as Vss. If you are running a single cell Lipo it will be real easy to stall the servo and cause a rather high current draw burning out the servo. (a stalled servo motor is the same thing as an electrical short).
I think you are in need of some advice in selecting your radio equipment. From here I don't understand what you are trying to do with the selection of the radio system I see in your ship.
Mini Q
Guess what rolled into the shop!! The new and improved Mini Q are here. What is improved? We now have a heavy layup over the spar and leave the material for the owner to trim to their needs. For Slope pilots, probably no trimming needed. For electrics, you can trim out enough for battery...
forum.alofthobbies.com
As to the nose I'd mix up any clear epoxy with white micro balloons and make a nice fillet. The color shouldn't be too far off, you might be able to adjust for it depending on the amount of micro balloons you use.
As the PWM voltage, few RX have voltage regulator or even one you can adjust. Most RX electrical bus bars are running the battery voltage as Vss. If you are running a single cell Lipo it will be real easy to stall the servo and cause a rather high current draw burning out the servo. (a stalled servo motor is the same thing as an electrical short).
I think you are in need of some advice in selecting your radio equipment. From here I don't understand what you are trying to do with the selection of the radio system I see in your ship.
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Cool, wet micro should do the trick. I might try and use flash tape, and even set an undercut, so I can still remove the nosecone. I'll report back on that.
Regarding the radio gear, it's been a bit since I last flew RC, and I see that the world has changed a bit since. Starting with the servos, I preferred to not pay $50/servo, so a buddy recommended $5 servos. In hindsight, a $20 servo might not have bothered me as much as the $5 garbage I hot-glue-gunned into the wings. As far as the Rx goes, that's where the world has changed the most. It took me a minute to decipher enough of the new tech to know what I was looking at, and a minute later I purchased the RX4R. Ultimately, what I was trying to do was put a 4 channel Rx in a 2 servo elevon ship. I chose a 1S lipo, because why in the world would I buy a NiCad pack, unless oh, the Mini-Q needs 60g of ballast. I'm not sure why the Rx and servo didn't get along, but the remaining 2 channels are working. The university of youtube taught me enough to setup my Taranis Lite Tx at the recommended throws and rates. Looking around for a grassy slope and a breeze for the first flight, ASAP.
What gear would you run in the Mini-Q?
Regarding the radio gear, it's been a bit since I last flew RC, and I see that the world has changed a bit since. Starting with the servos, I preferred to not pay $50/servo, so a buddy recommended $5 servos. In hindsight, a $20 servo might not have bothered me as much as the $5 garbage I hot-glue-gunned into the wings. As far as the Rx goes, that's where the world has changed the most. It took me a minute to decipher enough of the new tech to know what I was looking at, and a minute later I purchased the RX4R. Ultimately, what I was trying to do was put a 4 channel Rx in a 2 servo elevon ship. I chose a 1S lipo, because why in the world would I buy a NiCad pack, unless oh, the Mini-Q needs 60g of ballast. I'm not sure why the Rx and servo didn't get along, but the remaining 2 channels are working. The university of youtube taught me enough to setup my Taranis Lite Tx at the recommended throws and rates. Looking around for a grassy slope and a breeze for the first flight, ASAP.
What gear would you run in the Mini-Q?
Konrad
Very Strong User
This thread has a lot of good set ups. I use 8mm thick metal geared servos that can run off 2 cell lipos. I want the 8mm thick to fit inside the wing with no bump. I want metal gears as the wing will spin on landing (ground loop) allowing the ailerons to get hit by weeds and rocks. And I want a 7.4v to 8.4v for the power I need as the miniQ is a fast ship. Air loads will be high and put a lot of demand from the small servos.
I'd use the KST XO-8 or Blue Bird A10. Some of the Blue Bird and Corona servos should meet your needs. On a budget the Blue Bird BMS 127WV should work.
alofthobbies.com
I'd use the KST XO-8 or Blue Bird A10. Some of the Blue Bird and Corona servos should meet your needs. On a budget the Blue Bird BMS 127WV should work.
Blue Bird BMS-127WV 4.8Kg-cm 66.7oz-in 0.05sec-60°
From Blue Bird Model comes the BMS-127WV Digital Servo, ready to effortlessly move your control surfaces. Inside is a beefy metal gear train, riding on brass bushings and a coreless motor for better efficiency. Featuring a super wide voltage range, excellent torque and speed, it'll be a great...
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Get some of the Corona 843 servos for $10 each, I think those will be perfect for you.
alofthobbies.com
I do not recommend flying with your current servos. Chances are they are not going to do well. Then get this battery:
alofthobbies.com
I have updated the mini-q product page to show these servos as the default for this plane. Think they make a bit more sense for a plane in this price point.
Corona DS843MG Servo - 4.8kg (66.6ozin), 0.10 sec - 8.5g Digital Metal Gear
Corona DS843MG Servo. Dimensions23x9x23mm(0.9x0.35x0.9in)Operating Voltage4.8 ~ 6.0VOperating Current200mA ~ 220mASpeed0.12sec.60º/ 0.10sec.60ºStall Torque4.0kg.cm / 4.8kg.cmDead Band≤3uSecTravel40º/one side pulse traveling 400usPosition SensorHigh Precision Japanese PotentiometerBall...
I do not recommend flying with your current servos. Chances are they are not going to do well. Then get this battery:
4.8V 1300 2/3A NiMH Flat
Made of high quality matched NiMH 4 x 2/3A LSD cells with universal servo connector with 22 AWG wires.The highest, honest capacity you can get from a 2/3A! If anyone claims to pack more than 1300mAh into this sized cell, then they are dishonest, this is t
alofthobbies.com
I have updated the mini-q product page to show these servos as the default for this plane. Think they make a bit more sense for a plane in this price point.
Great! Although, the Corona 843 servos show out of stock at AH. Any word on when they'll arrive?
Also, regarding the 1300 AH NiCad pack, at 87g, it's a bit more than the 62g of lead, glue and tape I added to the nose cone. The 57g 700 AH NiCad pack (plus a couple of buckshot in the nose) might keep the total weight down a little more. That's if I can still get the weight moment resolved. What are your thoughts on that?
Also, regarding the 1300 AH NiCad pack, at 87g, it's a bit more than the 62g of lead, glue and tape I added to the nose cone. The 57g 700 AH NiCad pack (plus a couple of buckshot in the nose) might keep the total weight down a little more. That's if I can still get the weight moment resolved. What are your thoughts on that?
First flight today in moderate wind. We climbed up a large rocky hill dotted with sagebrush and more rocks (this is every hill where I live in So Cal), and walked up and along the ridge to a clearing where the wind was ripping across the top, whistling through the dry brush. I threw her into the wind, and began to try and steer her back in forth along the ridge top. Instead, I was barely able to control her as she sank down the hill. Bleeding altitude and refusing to lift, I cut the 2mm reflex to try and gain airspeed (for more control). She instantly dove downward, an indication that the 2mm reflex was working. But before I could switch the 2mm reflex back on, she turned into the hill and smacked into something hard.
The nosecone is kaput, the rear fuselage at the tail needs repair (buckled on one side), and one of the $5 servos retired. From the sound of the impact, I'm lucky the damage isn't much worse.
From re-reading the forum highlights, she must have still been tail heavy, as control was almost impossible, and airspeed seemed low for her sink rate.
I 3D printed a mold for a new carbon nosecone, which will be about 1" longer than stock, to compensate for the weight of the carbon/epoxy repair at the fuselage rear. The extra forward moment may also require less lead to balance the CG on the rebuild.
I'll have to drive an hour to the beach to find softer hills for the next test flight.
Thoughts, comments, and suggestions appreciated.
Any word on when those sweet servos will arrive?
The nosecone is kaput, the rear fuselage at the tail needs repair (buckled on one side), and one of the $5 servos retired. From the sound of the impact, I'm lucky the damage isn't much worse.
From re-reading the forum highlights, she must have still been tail heavy, as control was almost impossible, and airspeed seemed low for her sink rate.
I 3D printed a mold for a new carbon nosecone, which will be about 1" longer than stock, to compensate for the weight of the carbon/epoxy repair at the fuselage rear. The extra forward moment may also require less lead to balance the CG on the rebuild.
I'll have to drive an hour to the beach to find softer hills for the next test flight.
Thoughts, comments, and suggestions appreciated.
Any word on when those sweet servos will arrive?
Konrad
Very Strong User
Sorry to read about this.
I have a question for you. Are you using a switch to define the amount of reflex? Reflex is just a fancy term to define the elevator neutral with a flying wing. I control (set up) reflex with the elevator push rods, elevator trims and elevator control stick.
I strongly advise against adding nose length. Any side area ahead of the CG has a destabilizing effect. This is even more of an issue with the vertical fin being so close to the CG (close coupled). Please take into account dynamic stability. A long nose it not what you want in a ship you haven't been able to control.
I understand your desire to get some nose weight out. But weight is a rather distant concern in airplanes behind structural strength and controlability and drag. Remember that per the lift equation weight is a linear function. But that lift goes up by the square of the speed. This means that if you are heavy you only need a little bit more speed to make up for the needed lift.
All the best,
Konrad
I have a question for you. Are you using a switch to define the amount of reflex? Reflex is just a fancy term to define the elevator neutral with a flying wing. I control (set up) reflex with the elevator push rods, elevator trims and elevator control stick.
I strongly advise against adding nose length. Any side area ahead of the CG has a destabilizing effect. This is even more of an issue with the vertical fin being so close to the CG (close coupled). Please take into account dynamic stability. A long nose it not what you want in a ship you haven't been able to control.
I understand your desire to get some nose weight out. But weight is a rather distant concern in airplanes behind structural strength and controlability and drag. Remember that per the lift equation weight is a linear function. But that lift goes up by the square of the speed. This means that if you are heavy you only need a little bit more speed to make up for the needed lift.
All the best,
Konrad
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@Dave75 - A slight error in CG in either direction will make the plane horrible. You will know when you hit the magic spot. Yes, find a slope with soft landings until you get her dialed in. Pull out those servos, I simply do not trust them for this plane. You need the elevator input to recenter perfectly on these planes, so any slop in the linkages needs to be fixed, and good centering of the servo is a must. Such small inputs are needed for elevator that errors work against you in a large way.
When I did the maiden flights on the first one to fly in the US, it took me a lot of tries before I found the right CG. No one had any good numbers for the CG at the time. Luckily I was on a sandy hill, so the 20 throws into the ground did no damage.
All of a sudden I found the magic spot and BANG she flew great.
Hope this helps. The numbers the guys have published should be very close for you. Remember 1 mm is enough to make her flyable but a hand full. Might take you a couple of flights to find what you like. But you will know when you hit it as the plane will be faster and bang the turns pretty hard with little elevator movement.
When I did the maiden flights on the first one to fly in the US, it took me a lot of tries before I found the right CG. No one had any good numbers for the CG at the time. Luckily I was on a sandy hill, so the 20 throws into the ground did no damage.
All of a sudden I found the magic spot and BANG she flew great.Hope this helps. The numbers the guys have published should be very close for you. Remember 1 mm is enough to make her flyable but a hand full. Might take you a couple of flights to find what you like. But you will know when you hit it as the plane will be faster and bang the turns pretty hard with little elevator movement.
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