wjglynn

Dave,

You are correct in your interpretation of me using the circularly polarized patch antenna on both airplane and ground. I spoke with the Astron engineer and he stated that the "normal" method was to use a vertically polarized antenna on the plane and a circular on the ground or vice versa. My degreee is in computer science and not engineering. I have to get there through regression testing instead of comprehensive initial design . The 8db gain of the patch appeals to me so I am just going to try it. My application has the camera plane circling overhead and not flying to the next county like many of our AP comrades are doing. Payload, drag, and dimensions are not an issue on my Stik so I am hoping it works for my niche. If this works I plan to put the Astron on the coming E-GBS.

We have only been in this sport for about a year. My wife flies too and our trip to Joe Nall will just be to observe hopefully shoot some great pictures. In addition to my GBS I have a scratch Flybaby being refurbished and a Monocoupe in the box. I want to get my IMAA planes in order and more landings under my belt before flying at a Fly-In the size of Joe Nall. I am taking my Nikon D70s with a 80-200 f.28 lens plus a 2x multiplier and a monopod. I have shot horsejumping profesionally and find airplane fly-by's similar in the composition timing and action challenges. We will be tent camping and just taking in the event. Do you plan to be there?

Bill

wjglynn

Steve,

As usual, thanks for the good insight! The shot I am trying to get with the platform is one looking down on the target plane from in front and above it and also having the flight line further below in the background. It seems to me that this is the only angle that will provide the right perspective for a still picture of a flying RC plane. My hope is that this is within the phase angle you speak of? We will see.

A picture of an RC plane with nothing but sky in the background provides no appreciation of where or how it was taken. I have a pretty narrow acceptable composition requirement so if my video clears up long enough for me to point zoom and fire I will be very happy. The camera can only look back off the right side of the plane so views while positioning for a pass down the flight line left to right are not important to me. (For now, ha ha)

I am with you on the helmet thing but the guys at the field thing I am nutty enough already! Hey, I even considered putting a Yagi on a rifle stock.

Bill

S_Dave

Bill,

How about this idea--use another LHCP patch, with the 8 dB gain on the receiving end, and mount it on a hat or helmet like Steve suggested. That way you can have additional gain from both antennas, and when you are watching the plane, you will just naturally be pointing the antenna at the plane.

Using a linear-polarized receiving antenna with your LHCP transmitting antenna will cost you about 3 dB (one-half your power) compared to using two similar antennas.

I wish I knew more about programming, because there are some ham operators who build a azimuth-over-elevation antenna mounts to track the ham satellites. They have a computer program to track celestial objects and point their high gain (and narrow beamwidth) antennas at them. With such a program, you could use the Lat/Long/Altitude from the plane, compare it with your ground position, and do some kind of trigonometry (sp?) to point a really high gain antenna--or array of antennas--at the plane for a really good strong signal. Too many projects, too little time is my problem. Well, one of them anyway.

You're lucky to be blessed with a wife who also enjoys RC. All I have to do to clear out the kitchen at my house is to bring one of my planes upstairs and tinker with it on the kitchen table.... Maybe if I waited until she was finished eating dinner, it would be more peaceful. Huh! Shoulda thought of that earlier....

Cheers,

Dave

Brett Horton

My Feedback: (17)

Those of you flying the Lift Meister please check out my post in ARF's about the lift meister.

S_Dave

Steve,

Could you please tell us what your elevator/tail servo setup is like on your Lift Meister? Brett's post about the unfortunate crash of his plane invites information on planes like yours that have established good reliability records. Your plane is one of the best-built planes of any type that I've seen. I'd like to benefit from experience that you and Brett have accumulated and build a strong plane.

Thanks,

Dave
(and thanks again, Brett for your report in the ARF forum)

steve_molmer

Brett, Dave,
Sorry to hear about the crash.
I have never seen a robbart type hinge ever come out of a control surface unless part of the wing went with it. I have a lift master that I flew this morning out at the base that has so-far survived hitting a pine tree at 50 mph ++ and is still intact. (it had some damage but it was easily repaired.) That plane has now got about 250 fights or more on it and other that a few nicks, taped over small holes in the covering it is still ready to go.

One thing that most builder are yet to learn is that thin CA and 5 min epoxy are not for building they are for fixing problems at the field. Also be generous with glue, you can always wipe off the excess. The hinges that come with the lift master are fine for the Sunday flyer crowd but for my taste I use the heavy-duty robbars.

If you cleaned all the surfaces with denatured alcohol (type used for painting not from the drug store) and use ether 2 hour epoxy or a good asphaltic wood glue, the hinge will not come out. Also make sure you only use pin hinges were there is enough wood to lock down the pins with out weakening the part. The picts below are how I rig all of the planes this size. This setup is bullet proof when used with metal gear high power servos and a heavy-duty pull-pull setup.
I hope this helps.

Brett,
when you get the new plane let me know and I can give you a list of the additional components and mods to make the plane like a tank.
Best regards

Steve

S_Dave

Hey, Steve,

Good detail in your photos--Thanks!
It's easy to see the strong construction and the hinges, servos and linkage. Someone here at work also mentioned that Robart hinges were the way to go. I noticed on some versions of your LiftMeister, you add brace wires for the horizontal stabilizer but these aren't on this model. I'm guessing those are for the extra heavy payloads, yes? Thanks for the tips on the glue, and cleaning the parts before glueing.

Best regards,

Dave

hexhome

A reminder that it is always wise to fit a failsafe when using an autopilot can be found [link=http://hexhome.blogspot.com/2007/05/axel-lifter-attacks-secret-missile-base.html]here[/link]

steve_molmer

Ok,
Funny…. LOL……….
Nice bit of science fiction.
Call Art Bell, now their on RC forums to….

steve_molmer

I have been bombarded by several people asking me to post a step by step how to build and setup a video transmitter unit for a gas plane.
I know that this post covers a good bit of that but, I think the issue is a good general parts list and step by step installation of the components.

I am in the process of building a new gas tricycle gear lift master that should answer all the questions that may be out there about were to start and what to do to get the best bang for the buck.
I will start posting this step by step guide on Tuesday of next week.
Please note that the posts help everyone doing this kind of thing so please ask me questions on here rather than PM-ing me. That way everyone can see the answers at the same time.

Every one have a safe and fun Memorial Day Holiday and don’t forget those who have give us the rite to do so.
Cheers

Steve

JettPilot

My Feedback: (6)

Hi Steve,

I have been watching your project for some time now, and what you have been doing is very cutting edge and technically awesome. I have been doing lots of FPV flying, and contantly run into a wall on video range [:@] Running a 1 watt 2.4 video TX, and a standard receiver with a 14 dBi patch antenna, my maxium range is about 6 miles, beyond that the video gets lots of snow and noise in it without fail. I do not have any intereference issues, its just weak signal beyond that. How are you getting so much range out of your video system ? I do not want to use a dish antenna, or more directional antenna as aiming becomes more difficult. I would like to stick with 14 dbi but use a better receiver or preamp. What receiver or preamp could I get at a reasonable cost for 2.4 ghz ? Attached is a picture of my "Ground Station".

JettPilot

S_Dave

Hi, Jettpilot,

Neat ground station picture--very functional yet sporty-looking headgear you are wearing! Hey! Where are you located? I don't see any mountains or hills in the background. And, by your signature "Paradise" I assumed you were in Georgia, so that must mean you are in South Georgia, where they don't have mountains.

Q. I was wondering: What brand and model Receiver are you using.?

I'm looking forward to Steve's reply, and he will likely make a recommendation about your receiver noise figure, so I'm asking the question to prepare the way.

It's a warm and sunny, wonderful day in Georgia today. Hope you and the RCU members all enjoy a safe and happy Memorial Day, and like Steve said, may we always remember what it's about.

Cheers,

Dave

JettPilot

My Feedback: (6)

Hi Dave,

I am flying 4 video planes with live video and navigation, and working on number 5, unfortunately all of them are limited in range by my cheap 2.4 ghz video receiver [:@] Attached are pictures of my first 4 planes.

I am using the standard reciever that comes with the 2.4 GHZ TX from BWAV, the stuff is made by lawmate. It is a pretty cheap receiver, so im sure I need something better, but what ? Either a preamp or a new more expnesive reciever, it will be more expensive and I am expecting that, but I am sure Steve knows what is the best to buy that has a price within reason.

I am using a 14 dbi patch on my helmet with the reicever mounted right behind the patch on the helmet, so there is no coax line loss. This is about is good as it gets for this reciever, and I cannot use a bigger antenna on my helmet, so its time form something better. Help Steve [sm=drowning.gif]

I was looking at your project and there is an easier solution for one of your objectives. You talked about a 900 mhz link to transmit your GPS position to a map on the ground. An easier way to do this is just use the audio part of your 2.4 GHZ link to do this. There is a small chip called something like the "tiny stamp 3 " or something like that, that converts NEMA to audio that can be sent over your video transmitter. Its very easy, cheap, light, one less thing do deal with, and requires and much less equipment on the plane and at the field than building a whole new link just for map position.

JettPilot

wjglynn

Hey Guys, Joe Nall was stupendous! I shot about 1300 pictures while there. At some point I will get them posted on the net. We got there on Tues. and left on Sat. While there I bought a rubber isolation mount for the G38 and picked the brains of all the experts there I could find. Isolating my engine is pushing it out even further out so I have removed the spring starter. I am also adding rubber iso to the camera mount while I have the bird splatted on the bench.

Hey Jettpilot - haven't seen you post for a while. Good to have you back. I must comment about your post on the other thread about multiple 2.4 gig systems. We are flying the GBS with a Spektrum system on the plane and I am using a BWAV 2.4gig. 200Mw xmitter for the downlink. We have about 10-15 flights on this setup with no apparent interference with the controls. Perhaps my transmitter power is not high enough to wash out the receiver as you described? My last set of flights were completed with a patch antennas on both the plane and on the ground. I am still having some interference problems but presently am trying to resolve vibration issues. Some experts at Joe Nall told me that the type of interference I am describing is from high frequency motor vibration hitting the camera. I am beginning to suspect that the A/V jack in the camera might also be contributing to my interference. I may try surgery on the camera to solder it solid.

Later Guys!

Bill

S_Dave

Hello, Jettpilot,

Hey! Thanks for the great tip about running the NMEA on the audio channel--that's BRILLIANT! I'll be trying that as soon as possible. "Less is more." as walt whitman said, so I can get rid of one more piece of equipment and be lighter. Big smiles here.

Thanks very much for sharing the photos of your planes. Very impressive! Each photo shows a very pretty model. And the airplane is nice, too! There--I knew your lovely lady would be used to compliments like that, and didn't want to be less of an admirer (being from the South, and all....).

Best regards,

Dave

DiveBombDave

http://byonics.com/tinytrak/

Search google for Tinytrak3 review for more info, but that retail website has a lot of info and links. Hope this helps you out, Steve&Dave&Jett.

Dave

dzbum

My Feedback: (5)

This serial Modem is very simple, cheap and seems to work well also. [link=http://www.rc-cam.com/forum/index.php?showtopic=1691&st=0]http://www.rc-cam.com/forum/index.php?showtopic=1691&st=0[/link]

S_Dave

DivebombDave and Dzbum,

Thanks for posting that great info. That www.rc-cam.com site is a mother lode!
I've got a wrist GPS (Garmin ForeTrex 201) that we've been using with a RF modem. Soon as possible, it's getting hooked up to the video camera/audio channel setup and tested in the "lab."
The ForeTrex isn't a USB but rather is a serial output. We'll see how this works and report the results.
Time to go home and troubleshoot the home air con--thank heavens it's only high 80's here in Ga.

Thanks again, guys,

Dave

steve_molmer

JettPilot
Sorry about the delay in getting back to you.

A 14db patch antenna is not bad for a mid range system. For long range using a 1 Watt transmitter you need to use the type of antenna that I have been using on all of my planes.
If you look back thru the posts you will find the links to the 3dbi spherically polarized antenna for the transmitter and an 8dbm gain antenna with a wide beam width for the receiver. The two parts are key to get maximum range also look in to adding a 21 db gain low noise amp to the receiver antenna. Add the ground plane as stated in the post with the LNA mounted to the back of the ground plane. Remember to old adage in RF if you have $110.00 dollars to spend on a receiver/antenna spend $99.00 dollars on the antenna and $1.00 on the receiver.

I would try this first then maybe look in to a new receiver. The main problem that I see is the 14db narrow beam width antenna. You must have at least 75 deg horizontal and vertical to get a good signal with out having a very good aiming system on you setup. Also remember to always mount the antenna the plane pointing down.

I am working on modifying a diversity receive to solve a lot of the issues of the aiming problem. It should increase the range of most system out there by at least 200%. I should have the setup completed in a few weeks. I will post the whole setup at one time.

PS. from the video you have posted in the past your setup seems to work fairly well. The videos are grate.
Best regards.

Steve

steve_molmer

S Dave,
The Tinytrak3 is the best way to go, everyone is dead on this one.
All you need to do is attach it to the audio input line of your transmitter and to the serial port of your on board GPS.
On the ground I plug my audio out of the receiver into my laptop sound card. Running the software in conjunction with map quest or several other programs of your choice you can fallow the plane as it travels in just about true real time. It is also handy to find a downed plane. (not what I like to think about but it happens)

I would also have an OSD so as you fly you can see the important stuff, ie.. Battery level fuel level and the most important of all altitude.
Well time to go back to work.
Cheers.

Steve

JettPilot

My Feedback: (6)

Hi Steve,

Have you been flying ? Am waiting to see more pictures and posts of your projects

Im not sure I agree with you on the antennas. Having a circular polarization decreases the signal a bit, and using an 8 db receiver antenna instead of a 14 like I have would reduce it that much more... With my 14 dBI receiver antenna, aiming is not a problem. I am within 10 degrees or so aim at long range, I get it very close just by turning my head until I see the best video, so aiming is very accurate and easy to do. I need at least 14 dBi gain on the ground, any less would reduce my range. I like the idea of building the groundplane for the patch, do you think a ground plane would help the 14dBI patch ? Would you use the same 2 waveleinghts out the sides for this bigger patch ?

My vertical transmitter antenna has 3 dBI gain, and puts the strongest signal to the sides, exactly where I need it. I could try your spherical antenna on the plane, I will buy one and try to see if it outperforms the 3 dBi verticals I am using now... But I dont understand why the 3 dBi spherical should be much better...


I will also buy a good LNA to mount on the antenna, that is something I have been thinking about for a while now, I should have done it a long time ago. I found one, it is expensive at 140 dollars, but if it gives me 6 dbi and doubles my range, it will be well worth it I wonder how much difference it will make in the real world, I doubt it will be the 18 dbi they advertise, but 6 dBi would be enough !

I like the idea of the tunable receiver you use.

"I got tired of have so may receivers sitting around so I took a standard 2.4 ghz receiver made by cop and modified it using a controller board by 13UK.com that allows me to tune from 2.2 ghz to 2.5 ghz. This way I only need to have one receiver for almost any transmitter.
So far it seems to out perform any receiver that Ive used in the past. "

If I had any idea of how to wire this, I would buy this stuff and do it. Can you post a schematic or how you did this ?


JettPilot

steve_molmer

Jettpilot,
Here below you will find the Basics of how and were I found out how to setup my receiver. I have also included a few photos of my ground station out at the field.
I will try to take a few more photos of the unit it self when I get back in town in a few days. I will also post some info on the antenna setup. I think when you see how well the patch the ground plane and the LNA work together you will understand why I said that it will work better than the 14 db you are using now. I hope this helps.
Regards I can not post all the pdf's here. if you pm me I will email them to you.

Steve

JettPilot

My Feedback: (6)

Thanks for the pictures Steve, I PM'ed you to get the .pdf files. I desperately need to upgrade my video receiver, so this information will be a great help. You cannot argue with success , so I will try the patch, ground plane, and LNA also as you suggest. With a little luck I will break through this 6 mile wall I have been hitting !

JettPilot

steve_molmer

Jettpilot,
I have tried to send the documentation on the receiver several times now and my email comes back saying your address is blocked. Can you set up a new email account with yahoo or another providers temporarily and I will try to send them again tomorrow night.

The reason why the 8db gain patch is a better choice than the 14db gain antenna you are using is in one word direct-ability. The problem people are getting in to here is that they keep thinking in terms of the point to fixed point broadcast, you need to look at your plane as the flying TV station and your ground station as being the home TV. As you said you can move your antenna slightly and the received signal improves, If you use a wide beam angel antenna that in not so directional your signal will only fall off gradually instead of so abruptly. Not to mention that the return los on a standard 14db ism band 30 deg beam width antenna with out a ground plane can be as much as 4 to 5 dbs with a noise figure near 3. If you use an 8dbm patch center tuned to 2.45 Ghz with a vertical beam width of about 70 degs and a horizontal of about 80 degs, then add a ground plane and a good LNA you can see a true usable gain of about 26 to 30 db. You only then need to face the antenna in the general direction of your plane to get a good signal. Now as far as range goes it depends on the rest of your setup and the environment you are flying in, but I have seen first hand distances up to 60 to 75 miles under the rite conditions.
Regards[8D]

Steve

wjglynn

Hey Steve,

Yesterday I completed my first set of test flights with the engine rubber isolated and the camera mount rubber isolated as you suggested. I had mixed results, the best being when the plane was at high altitude and the G-38 at an idle. What I did want to share with you and the others was the results of my antenna tests. I have an 8db patch on both the airplane and on the ground. Both antennas mounted in a horizontal position and no ground planes yet in place. The transmitting patch is bolted on the bottom of the aircraft with about 2inch nylon bolt standoffs pointing downward. I had my pilot fly vertical ovals parallel to the flight line to keep the flight line in constant view of the camera. I was mildly suprised that reception was very good when the plane was inverted and the transmitting patch pointed skyward. While the plane was always fairly close distance wise he would make a pass in front of me upright and then come back inverted the other direction. The only time the signal would drop out was during the transition from upright to inverted. The conclusion here was that at least at close range a patch to patch works well as long as they remain parallel to each other. I did not expect this performance off the back of the patch.

I plan to two more test flight days with this plane and then I will migrate the system to the E-GBS currently under construction.

Bill