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Bob Cat Copy Falcon 120 Jet

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Old 07-09-2008, 08:56 AM
  #1301
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Default RE: Bob Cat Copy Falcon 120 Jet

SUCCESS!

I flew my Falcon yesterday and all went well. It's super easy to fly and land. With full flaps and a lot of residual thrust from the big Ram 750, I had to shut the engine off 200 yards out and let it glide from there.

For the first flight, I flew around at half throttle. My buddy and I looked at the wing, and man there is a lot of flex in there. I am thinking of getting another, stripping the covering on the wings and adding some carbon to make a stronger set so I can be a little crazier with her.

Regarding the engine mount. I have strips of 3/8" wide by 1/" thick carbon strips on edge from the back of the mount to about 6 inches in front of it tied into the side of the rib inside the fuse. I used a dremel to cut a slot and then glued it in with Hysol.

Tumbler


Quote:
ORIGINAL: tim777jet

Following a bounce that damaged my L/H main gear mounting last month, I had a really good inspection around the airframe. I noticed a slight hairline crack around the side of the fuselarge at the front of the engine mounting structure. I found that both sides of fuse had in fact cracked right through and after loading the engine mounting, i opened up the hairline cracks to show the extent of the damage. The structure in this area is adequate, but if the large balsa block (which is fitted inside the extreme rear the fuse during manufacture) had been extended say a couple of inches further fwd, it would have increased the strength in this area considerably. It is a nasty area to have to work in and there were many different ways to repair and strengthen the area, but I used simple engine bearers each side, bonded to the top of the engine mount area and one bolt fitted trough for extra piece of mind. The bearers are glued to the wind root ply formers and a 3/4 inch balsa block was shaped to fit inside the fuse right at the back and two additional balsa/ply blocks bonded to the rear but one frame to carry the ends of the bearers. Seems to be nice and strong now and bear in mind, my home built engine is a lot heavier than a comercial engine and to be fair, the plane has endured quite a few less than perfect landings and all on grass.
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Old 07-09-2008, 01:33 PM
  #1302
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Default RE: Bob Cat Copy Falcon 120 Jet

Congrats Tumbler, It should scoot along with a ram 750. I have a Super Bee on mine so it runs wide open a lot.
What was you empty weight ?

Cody
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Old 07-09-2008, 01:36 PM
  #1303
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Default RE: Bob Cat Copy Falcon 120 Jet

Thanks man. I actually never weighed it so I am not sure. It took off in about 100 feet and glides forever, so it is very lightly wing loaded even with the big 750 thats for sure!

Tumbler


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ORIGINAL: Grodus

Congrats Tumbler, It should scoot along with a ram 750. I have a Super Bee on mine so it runs wide open a lot.
What was you empty weight ?

Cody
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Old 07-09-2008, 03:40 PM
  #1304
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Quote:
ORIGINAL: tim777jet

Following a bounce that damaged my L/H main gear mounting last month, I had a really good inspection around the airframe. I noticed a slight hairline crack around the side of the fuselarge at the front of the engine mounting structure. I found that both sides of fuse had in fact cracked right through and after loading the engine mounting, i opened up the hairline cracks to show the extent of the damage. The structure in this area is adequate, but if the large balsa block (which is fitted inside the extreme rear the fuse during manufacture) had been extended say a couple of inches further fwd, it would have increased the strength in this area considerably. It is a nasty area to have to work in and there were many different ways to repair and strengthen the area, but I used simple engine bearers each side, bonded to the top of the engine mount area and one bolt fitted trough for extra piece of mind. The bearers are glued to the wind root ply formers and a 3/4 inch balsa block was shaped to fit inside the fuse right at the back and two additional balsa/ply blocks bonded to the rear but one frame to carry the ends of the bearers. Seems to be nice and strong now and bear in mind, my home built engine is a lot heavier than a comercial engine and to be fair, the plane has endured quite a few less than perfect landings and all on grass.
Tim,
After reading your post, I thought I should check my engine deck for cracks. I dont have any yet after 40 or so flights. Thanks for posting, I will check that area often.
Did you install the small cf rods that go from the trailing edge of the wing into the engine mount plate? Looking at your pics, It looks like you did. I am working on another Falcon with some improvments. The newer falcons have 4 wing bolts rather than 2 and I though about omitting the small cf rods but after this, I will make sure I put them in. The cf rods have to help some. I overlooked the need for additional support in that area until you pointed it out.

Cody
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Old 07-09-2008, 03:54 PM
  #1305
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Default RE: Bob Cat Copy Falcon 120 Jet

Cody, are those the rods 1/4" x 1 5/8" long ?

... zak
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Old 07-09-2008, 04:05 PM
  #1306
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Default RE: Bob Cat Copy Falcon 120 Jet

Hi Cody, yes i have the small carbon rods at the end of the wing, they must help in taking some of the load at this point. I toyed with the idea of drilling two holes right through the balsa decking block and inserting carbon rods right through and up to the next fuse frame, but stuck with the engine bearers at the moment. I was also going to fit two small carbon rods above the engine bearers but angled down towards the rear of the decking to act like an A frame. The carbon rods would be in tension now instead of shear, to assist any downward loads imposed on touch down, but will see how the first idea works out. cheers Tim
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Old 07-09-2008, 09:37 PM
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Default RE: Bob Cat Copy Falcon 120 Jet


Quote:
ORIGINAL: starzak

Cody, are those the rods 1/4" x 1 5/8" long ?

... zak
Yep Zak that's them. I just looked for them in my new kit and only found one. I cant remember now if there should be 2 or I cut that one in half. I guess I will look in my other new kit. I bought 2 more while they were on sale.


Tim,
keep up posted please on how that works out. It seems like I remember that you have a rather heavy engine. Hopefully, a lighter engine will help in my case. You have trailing link gear too dont you? I have a plans for fuel in the area forward of the balsa block on my next one. I hope that doesnt make things worse. It will be empty on landing though.

Thanks,
Cody
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Old 07-09-2008, 09:44 PM
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Default RE: Bob Cat Copy Falcon 120 Jet

Has anyone tried Hitec HS-125 thin wing servos for the rudders on the Falcon? Is so, are the adaquate for the job
?

Thanks ,
Cody
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Old 07-10-2008, 09:51 AM
  #1309
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Default RE: Bob Cat Copy Falcon 120 Jet

I hope a T-750 engine will be ok on my Falcon120!
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Old 07-10-2008, 02:52 PM
  #1310
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Default RE: Bob Cat Copy Falcon 120 Jet

Identical size as my 750 in the pics above, but i would not fly it on the full 24lbs of thrust you have! I would really like stronger wings with even the 18lbs of thrust I have. I can flex the wings by holding the wing near the boom and pushing down the wingtip. It flexes up and down at least 1/2-3/4" each way. I think if i did a power dive or too hard a turn it would be all over. When I had the covering off the bottom I wish i would have strengthened it. It might be ok, but I would hate to snap a wing on mine.

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ORIGINAL: GreenAcre

I hope a T-750 engine will be ok on my Falcon120!
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Old 07-10-2008, 04:59 PM
  #1311
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Default RE: Bob Cat Copy Falcon 120 Jet

Tried a smoke system on the falcon today, too windy to fly so just did a quick run, no electric pump, just an old retract phneumatic bottle and ordinary diesiel fuel from petrol station, air pressure @ 80 psi, 3mm RS brass tubing crushed down to @ -020 thou at the end, bottle held 125 ml run time @ 30 secs, will post more details later, no time now

www.youtube.com/watch?v=TJmZRx35BgY

I was concerned about any flame breaking past the turbine and setting light to the diesel being injected into the engine, during heavy accel from low power settings, so searched the web for info, but couldnt find any help. I did find a company who sell smoke systems and their own smoke fluid called MT smoke oil. This is completly non hazardous, but it does burn. As the weather was so bad the past couple of weeks, I thought I would try the smoke system on the ground, with the tail and booms missing and see if the fluid would catch fire during accels. The MT fluid produced good smoke and Did momentarily ignite during rapid accel. The extent of any flame could not be seen due to the sunlight. I then did a test with ordinary Diesel from a gas station and the results I would say, were the same, except it was hard to determine if I got a momentary ignition. The engine was running at 100,000 rpm and throttled down to 45,000 rpm and back up, and then inbetween. It might be that i can squeeze the end of the pipe down a little more and let the smoke run for a few extra seconds, but want to try the system in flight as the airflow might diminish the effect of the smoke. It will be interesting to see how the airflow and tailplane, alters the flow of smoke. I was gutted i couldnt fly due the severe winds we have had in UK, will have to wait another couple of weeks now.

I only have a 7 channel set, so linked the smoke valve to the retract signal, gear up/smoke on. I dont want too much extra weight, so 125ml @ 30 secs will be good for me.
Obviously if i used an electric pump, i then have added weight with the unit and batteries ( or complexity linking into the receiver pack), but most important, i cant switch the system off and fly with the gear up, so an electric pump would run dry and damage would ensue, hence the air tank system which works really well and is light.
The plastic bottle I used was an old Radseal bottle, but if you try this, then do a pressure test of your intended container first with water, not air. This plastic bottle held over 100psi no problem but remember, when the air is introduced, the end of the pipe is open, so pressure will be less than the air pressure in the tank. You could use another metal air tank for fluid containment. I used one NRV from the air tank to the shut off valve and then to the plastic container. I used another NRV from the outlet from the plastic container to the spray bar, so the exhaust gas velocity would not syphon the fluid out, requiring some possitive pressure to overcome the spring pressure in the valve. Pipework will be tidied up later.
Hope that gives some helpful tips on a simple, light, easy to install system that works without requiring any more chanels.
Happy smoking, cheers Tim
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Old 07-11-2008, 08:47 AM
  #1312
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Default RE: Bob Cat Copy Falcon 120 Jet


Quote:
ORIGINAL: tim777jet

Tried a smoke system on the falcon today, too windy to fly so just did a quick run, no electric pump, just an old retract phneumatic bottle and ordinary diesiel fuel from petrol station, air pressure @ 80 psi, 3mm RS brass tubing crushed down to @ -020 thou at the end, bottle held 125 ml run time @ 30 secs, will post more details later, no time now

www.youtube.com/watch?v=TJmZRx35BgY

Hey Tim,

Is there any concern some raw fuel could burn on the horizontal stab in flight and cook the tail?

Jeff
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Old 07-11-2008, 10:04 AM
  #1313
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Default RE: Bob Cat Copy Falcon 120 Jet

By the way, scratch this idea. I need to get one made from stainless steel. The first time I started the engine, I had a nice flame and it melted the alluminum right through. Don't try this at home!

Tumbler


Quote:
ORIGINAL: TUMBLER

This took less than 5 minutes to work, it's light, compact, and best of all no ugly tape on the bottom of the stab!

2 hours to test flight for me!!

Tumbler
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Old 07-11-2008, 11:47 AM
  #1314
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Default RE: Bob Cat Copy Falcon 120 Jet

Servo Extensions?? What are you guys using? I have 3 y-leads for the rudders,ailerons,flaps. (I am using one servo for the elevater). I figure 4 12" for the ailerons/flaps 2 36" for the rudders and one 48" for the elevater. And some 6" extensions coming from the Rx. to connect everything.
Thanks!
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Old 07-11-2008, 12:04 PM
  #1315
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Default RE: Bob Cat Copy Falcon 120 Jet

Good luck. I spent over $100 on servo extensions for this plane. The main reason I needed so many was to have connections where the booms meet the wings, and where the wings meet the fuse, so I could take it apart if needed. If it helps I'd have to look up exactly what I bought.

Joe
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Old 07-11-2008, 12:07 PM
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Default RE: Bob Cat Copy Falcon 120 Jet

There are so many freakn extensions I didn't even want to think about it, so I used a bunch of longer extensions, cut and soldered most of them to the length I needed.

Tumbler
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Old 07-11-2008, 12:14 PM
  #1317
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Default RE: Bob Cat Copy Falcon 120 Jet

I soldered a wiring harness. Used 2 large wires for the + and -. A couple of smaller wires for signals and MPX connectors for everything.
Works a treat and I only have to undo 1 connector at each junction. Worth the work but you must know how to solder well.
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Old 07-11-2008, 12:19 PM
  #1318
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Default RE: Bob Cat Copy Falcon 120 Jet

If you look back to about the middle of this thread you will find postings and schematics from a guy who made up servo harnesses using Multiplex connectors. That way he has one plug at each assembly point. Fortunately mine just fits in my truck without dis-assembly so it hasn't been a problem.

Joe

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Old 07-11-2008, 12:20 PM
  #1319
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Default RE: Bob Cat Copy Falcon 120 Jet

Guess he beat me to it. See erraz's posts earlier in this thread.

Joe
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Old 07-11-2008, 12:24 PM
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Default RE: Bob Cat Copy Falcon 120 Jet

Joe,

I put mine in my SUV with the wings hangine an inch out the window. I leave the stab attached the boom and just have to screw the 4 boom bolts on and that's it. It's still a pain to get it in the car with the wings on but much easier than taking the wings off!!

Tumbler


Quote:
ORIGINAL: joeflyer

If you look back to about the middle of this thread you will find postings and schematics from a guy who made up servo harnesses using Multiplex connectors. That way he has one plug at each assembly point. Fortunately mine just fits in my truck without dis-assembly so it hasn't been a problem.

Joe

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Old 07-11-2008, 12:28 PM
  #1321
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Default RE: Bob Cat Copy Falcon 120 Jet

Thanks guys! I have some extensiona left over from other projects. All HD of course.
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Old 07-11-2008, 12:41 PM
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Default RE: Bob Cat Copy Falcon 120 Jet

Quote:
I put mine in my SUV with the wings hangine an inch out the window
I have a Ford Expedition and if I put it just behind the front seat at an angle it just fits fully assembled. It's a real hassle if you have to break it down each time, but it flys so great it's worth it. I've got 31 flights on mine so far.

Joe
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Old 07-11-2008, 12:51 PM
  #1323
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Default RE: Bob Cat Copy Falcon 120 Jet


Quote:
ORIGINAL: GreenAcre

Servo Extensions?? What are you guys using? I have 3 y-leads for the rudders,ailerons,flaps. (I am using one servo for the elevater). I figure 4 12" for the ailerons/flaps 2 36" for the rudders and one 48" for the elevater. And some 6" extensions coming from the Rx. to connect everything.
Thanks!
GreenAcre, how did those lengths work out for you ? Were they accurate ? Reason I ask is that I haven't purchased any yet, and I'll probably be doing something similar. I'm fortunate enough to have a full size van, and hope to be able to leave it all together permanently. I'm assuming that you didn't use a connector between the wing and the boom. Is this correct ?

... zak

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Old 07-11-2008, 12:59 PM
  #1324
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Default RE: Bob Cat Copy Falcon 120 Jet


Quote:
ORIGINAL: TUMBLER

By the way, scratch this idea. I need to get one made from stainless steel. The first time I started the engine, I had a nice flame and it melted the alluminum right through. Don't try this at home!

Tumbler


Quote:
ORIGINAL: TUMBLER

This took less than 5 minutes to work, it's light, compact, and best of all no ugly tape on the bottom of the stab!

2 hours to test flight for me!!

Tumbler
But Tumbler, that aluminum stove pipe that you made, was thicker then any tape glued to the bottom of the stab, don't you think ? ? ? [] It should have offered better protection then the tape.

... zak
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Old 07-11-2008, 01:02 PM
  #1325
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Default RE: Bob Cat Copy Falcon 120 Jet

Starzak,
I am just building mine. I have built other jets thats needed extensions and I am going by what I need from that. But those ext. should be fine. Most likely when I transport mine I will take the wings and off and leave the booms attached to the stab. (elavator). No connector. I will just connect the extensions togther when I am at the field.
Thanks
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