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twinturbostang

New FPV Milestones for me!

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Wow, what a morning. I set several personal FPV milestones today. The weather was just perfect, so I had to get in a morning flight before work. :D Part of the problem with living in the Washington D.C. Metropolitan area is it's hard to find a nice big field to fly from, that's away from roads and people. Well, I finally found a pretty good spot, which is a large soccer/baseball complex. During the weekends it's pretty busy with lots of games going on. But during the week, there's nobody there. :)

Milestones? Well, the biggest is this was the first time I flew FPV by myself. Nobody with me to buddy box in case of video loss. As a result I was quite nervous at first. This was also the first time flying with a patch antenna (RC-Cam's GP Patch), which worked very good! It appears to have a nice wide beamwidth. At one point I was flying pretty high back to the launch point, and got a little bit of static. I believe I was going outside of the beam at that point. But a quick drop in altitude brought the signal back to full strength.

I do have a concern though, and that is receiver glitching at distance. At far distances, I was starting to have some glitching. I couldn't "feel" it in the control surfaces, but I could see it in the pan servo on the camera. Although I do have a servomax module installed (doubles the rotation to 180*). So any slight twitch is magnified. Anyway, I estimated I flew out to around 0.5 miles. However, after checking Google Earth, it turns out I was only 0.25 miles away from the launch point! The entire field is 0.5 miles across, but I did not feel comfortable going any further than halfway. Even that seemed rather far though. At that distance I could not hear my plane at all.

So what are you guys using for RC receivers? I have a Berg 4L in the plane right now (soon to be replaced w/ a Berg 7P), which is supposed to be really good. I am running 600mW of power on the video though, so I'm wondering if that's causing problems. However, there are a couple of guys on RCUniverse that have the exact same video Tx I have, and have gone out to over 1 mile away. Not sure what kind of receivers or setups they are running though.

Well, that's it for now. I had a good time. And hopefully with continued flights, I will become more comfortable flying FPV to further distances. I recorded the flight and will try to get it online sometime today or tomorrow.

Brian

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Nice! Isn't FPV flying a blast? I always get kinda nervous/giddy when I fly because I almost never have a spotter/buddy box pilot and I usually fly way beyond visual. I am using a 450mw 1.2 system with a GP Patch and its on a SS. I am using a Hitec Flash 4 with a Hitec Supreme 8 channel RX. The RX is mounted at the back of the SS and the video TX is mounted right behind the motor so they are as far away as possible. My farthest flight is .8 miles away and I never got any video snow or static and didn't notice any glitching. I am scared to fly farther without a RTH(Return To Home) GPS module becuase I would be sick if I lost control and lost the plane. Not to mention the possible damage or injury to somebody if the plane happened their way. I am planning on getting a Glitch Counter so I can see how many hits I'm getting when I next fly that far away again. The weather has been miserable here in Michigan lately...

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Thanks for the reply. I'm not sure if I can sepparate the two any farther or not. I'm flying a GWS E-Starter. The receiver is mounted as far back in the fuse as I can get it. And the video transmitter is located on top of the wing, right behind the camera, which is close to the CG location. Probably only about 6" apart.

Anyone else?? Been pretty quiet in here lately.

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I know this is hard to test if you are only seeing a small glitch (amplified) on the pan servo, but are you sure that its not interference from the motor and it happens with no video TX switched on?

Separation is the best fix, but certain Rx's are much better. Airtronics have a good noise rejection I know. You can use a Notch filter and preamp on the TX if its a real issue though.

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I know this is hard to test if you are only seeing a small glitch (amplified) on the pan servo, but are you sure that its not interference from the motor and it happens with no video TX switched on?

I've never done a range check from 1/4 mile away, so I really don't know. lol I'm working on a new platform (TwinStar II) that will separate the RC receiver and video Tx by a good distance. So we'll see how that performs. If I still have problems, then I'll have to dig deeper.

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Your reduced range is probably caused by your Video TX being close to your RC receiver. With my Video TX being mounted out on the wingtip, running 5 watts video at 2.4 GHZ, I have been 1.5 miles at 400 feet with an FMA FS8 receiver. With a JR receiver, it goes over 2 miles at 400 feet before I start to see it go into fialsafe. The higher the plane is, the better it gets, at 1000 feet you can be further away.

For the video portion of the signal, on another plane, with BWAV 1 Watt video TX, 3 dBI TX antenna on the plane, and a 14 dBI patch receiver antenna, I have gotten 6 miles of good flyable video. At 6 miles, you need to be high, at least 400 feet ;) The video was just starting to get enough static to start seeing in the goggles, but still very flyable and not near to he point of dropping out .

JettPilot

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JP, I like the way you keep the Video TX away from the R/C RX, I think a few people would be surprised how much further they could fly if the were as carefull as you. I fly over a mile on 100mW but I keep hearing of people using 500mW and 600mW systems that dont get that far. I don,t have as good separation as you but my video gear is mounted in the nose with no connections to anything else and 4" gap to the nearest wire.

Terry

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Jett, I have since moved my video gear over to my TwinStarII. I have my FS8 mounted about 2 feet away from my 600mW video transmitter. And it seems to be doing much better now. Yesterday I flew out to 0.3 miles away with no glitching. Yeah, I know.. nothing like 1 or 2 miles away! But I'm working up to it. Not going to take any chances! Plus it had snowed, and there was a severe amount of moisture in the air. Looked like I was in the clouds actually! I started to get some video drop outs as a result of that, so I brought her back in. When the weather clears up, I plan on doing farther and farther flights.

Edited by twinturbostang

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TTS, got any details or links to your twinstar setup?

I am putting one together in advance of next season.

It's going to have counter rotating 400XT motors on 8x6 props, and CC TB 18 ESC's.

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Well, I can list all of the major components...

TwinStarII:

Dual 400F brushless motors (rc-dymond.com, justgofly.com, etc)

Dual CC Thunderbird 18 ESC's

APC 6x4 props

Two ThunderPower 3S 2100 Lipos in parallel for 4200mAH total

FMA FS8 Co-Pilot/Rx (co-pilot currently not hooked up but will be in the future)

6 servos (2 ail, elev, rud, camera pan, camera tilt)

Dimension Engineering ParkBEC

Video gear:

Black Widow 600mW 2.4GHz Tx

KPC-S226 (aka KX-131) camera

Pan/tilt unit (details can be found on rcgroups)

RC-Tech Head tracking

Dimension Engineering 5V switch reg. (powers video Tx and camera via main flight pack)

Ground Station:

Black Widow 2.4GHz Rx

I-Glasses video goggles

Canon Elura 2 MC miniDV camcorder

Tripod, etc.

3S 2000 Lipo powers video Rx and I-Glasses

The plane has tons more power than needed. I can comfortably cruise at 1/4 throttle. Kick it up to full power, and she goes vertical at 43 Amps! That's a sight to see! LOL But at normal throttle settings, she will fly for at least 30 minutes I think. Haven't timed it yet, but I will do that sometime. AUW without video gear is about 42oz and with video gear is about 47oz (if I remember correctly).

I've got 4 FPV flights on it so far, and really like it. It's so cool to pan to the side and see those props spinning right next to me. Feels like I'm really in the plane! :) I've been recording my flights and will be putting together some videos. So far I've used the standard whip antenna and GP patch on the Rx, depending on where I fly and what I'm doing (local circuits or long distance). Recording flights with the miniDV camcorder gives by far the best quality available. I looked into some of the SD card recorders. While they are more convenient not having to "capture" the video to the computer, they do compression on the video, so you never get to see the true quality of it.

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I have to agree TTS that the SD recorder doesn't record the video in true quality. Mine sucks! I'll have to wait next month for a Pinnacle like Kilrah's! Too bad my Sony mini DV motherboard fried unsuspectingly it would of been perfect.

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Sounds like we are on the same track.

Mine's going to have

Dual Esskay 400XT outrunners

Counter rotating 8x6 APC props

Dual Thunderbird 18 ESC's

6 servos, same as yours.

I'm planning on using the BECs of both ESC's, so I'm not going to add a seperate BEC.

I haven't picked batteries yet.

I may experiment with an autopilot or one of the RTB devices in the future, so the extra room in the fuselage is going to be useful.

I'd be curious to see how you have the camera and pan/tilt mount assembly on the airplane, and the FOV you are able to achieve. I'd prefer to keep mine as far aft as possible, but am concerned the nacelles will block a large part of the view at the sides...

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I'm planning on using the BECs of both ESC's, so I'm not going to add a seperate BEC.

I wouldn't do that. There's no telling what the performance of the two linear regulators in parallel will be. Well, I didn't want to take any chances anyways. If it fails in mid flight, you're done! So I decided to use an external BEC.

I may experiment with an autopilot or one of the RTB devices in the future, so the extra room in the fuselage is going to be useful.

Actually, it gets quite crowded in there with all the gear. Anything you can move to outside the plane will help. My two 2100 packs take up quite a bit of room. The problem is that there's a narrow, long channel that runs through the plane. It's originally designed to carry a string of Ni-cad or Ni-mh cells. You will need to do some planning beforehand and figure out where everything is going to go.

I'd be curious to see how you have the camera and pan/tilt mount assembly on the airplane, and the FOV you are able to achieve. I'd prefer to keep mine as far aft as possible, but am concerned the nacelles will block a large part of the view at the sides...

I will have some pictures up soon. My camera mounts where the stock canopy goes. I made a platform from light ply and the pan/tilt sits ontop of that. The nacels are not in the way at all with the majority of the camera pan. Only at the extremes do they come into view. And actually... it's a VERY COOL effect panning your head to the side and seeing the props spinning "next to you"! :-) It really makes you feel like you're riding in the plane!

Edited by twinturbostang

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I wouldn't do that. There's no telling what the performance of the two linear regulators in parallel will be. Well, I didn't want to take any chances anyways. If it fails in mid flight, you're done! So I decided to use an external BEC.

Did that a number of times, never had a problem.

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I didn't think that paralleling linear regulators was really recommended. Here is an excerpt from the National website:

Can I parallel two LM78xx linear regulators?

Paralleling of 3-terminal regulators is generally not recommended because the devices will not share current equally. If, for instance, you try to make a 2 Amp regulator using two LM7812s or two LM7815s, the device with the higher output voltage could be carrying more load than the other. Or even worse, the second regulator may be totally off. The reliability of such a system is poor because of the combination of high temperature and high current in the first regulator.

A simple way to improve sharing is to insert a low value resistor (about 0.1 Ω ) in series with each output. The problem with this approach is that load regulation is poor, because the voltage drop across each resistor will vary as the load current varies, in this case 0.1V error for full load of 1A per regulator.

A better solution is to use either a linear regulator with a sufficiently high current limit, or a linear regulator controller with an appropriate pass transistor. For this example, the LM1085 quasi-lowdropout (QLDO) linear regulator would be a good integrated solution, or the LP2975 controller could be used for a more customized design. See the online design environment of the Power WEBENCH for recommended regulators to meet your system specifications.

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Castle Creations has posted many times that they recommend using their Phoenix line of ESC for parallel operation because the additional programming (Fixed throttle, current limiting disabled) offers more flexibility, but they have also stated that it's fine to parallel the BEC's on the T-birds.

FWIW, I don't know what regulators they use on their speed controls.

Edited by rob10000

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I didn't think that paralleling linear regulators was really recommended.

You are correct, but I am not trying to get double power from using 2 BEC's. I only draw the current that could be supplied by 1 BEC but having 2 is more of a safty net.

I connect each BEC with the standard thin servo wire of equal lengths to a Y connector plugged into the RX. The equal length wires act as a balance to help the BEC's share the load. It has worked well for years now so I don't expect any problems.

Terry

Edited by Terry

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Onward and farther. Flew a couple of FPV flights today, and went out to 1/2 mile. Very small amount of glitching was observed in the camera servos at that range. It also was mostly just when I was turning around. I have the RC antenna strung out the wing, so when I turn, the antenna is out of alignment with the transmitter. Also, if the camera had been hard mounted, I wouldn't have even noticed it probably. My guess is you can tolerate some degree of glitching in the control surfaces and not notice it due to the slow response of the plane relative to the fast glitching. With the camera on pan/tilt servos however, it is immediately apparent if you have ANY glitching at all. I have my pan servo modified for 180 degree operation, which is effectively double the range. So any glitching I get is perceived as twice as strong also. Given this, I felt comfortable out to 1/2 mile. I was at a different field today, and that was about as far as I could go. So I'll have to look for another place to try farther.

BTW, video downlink was super! Using the 600mW Tx and Mr RC-CAM's GP patch design yielded great video with no dropouts or even a hint of dropout at range. :)

Edited by twinturbostang

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I may experiment with an autopilot or one of the RTB devices in the future, so the extra room in the fuselage is going to be useful.

Actually, it gets quite crowded in there with all the gear. Anything you can move to outside the plane will help. My two 2100 packs take up quite a bit of room. The problem is that there's a narrow, long channel that runs through the plane. It's originally designed to carry a string of Ni-cad or Ni-mh cells. You will need to do some planning beforehand and figure out where everything is going to go.

Here's what I did to maximize the interior space. I have no idea what I'll put in here besides FPV gear in the future, but I wanted to maximize the area before I glued the halves together...

I made my cockpit area bigger with a dremel router attachment and this high speed cutter..

115_pd.jpg

565_pd.jpg

I used a steel ruler laid over the mating edges for the base to glide on, set the depth for a consistant depth, and started making dust!

The area is about 2.25" wide, and goes all the way back. I sized it for my 3S3600 lipo. Now I can lay it flat and slide it from end to end in the compartment as needed, because it'll fit under the HS-81's.

4108175397.jpg

4108190261.jpg

EDIT***

BTW, I got my 3S3600 pack from HERE

for only $34. Granted, it's *only* a 10C pack, but that's still 36 amps. :P

Edited by rob10000

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Cool! Looks great. Don't hog it out too far though, or you will loose some structural rigidity in the nose.

The more I look at it, the more I'm thinking of doing something similar. Right now I've got both of my 3S2100 packs mounted end to end, which puts one completely under the wing. It's hard to move stuff around like that. I need to put them side by side, but in order to do that, I've got to hog it out also. But the servos are in the way, so I've got to figure something else out. I suggested to a buddy to mount the servos out in the tail and direct drive them. He did that and it works great. So I might try it also. I just worry about long servo leads though.

Edited by twinturbostang

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Cool! Looks great. Don't hog it out too far though, or you will loose some structural rigidity in the nose.

You could always put some carbon fibre shafts through the remaining foam in a front-back manner. This would make it quite very firm again.

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