RE: Bob Cat Copy Falcon 120 Jet
yes it was my post about the servo arm crack at the splined hub, but with 2 servos on the elevator, it is unlikely that 2 failed at the same time, but one could have failed many flights before and the other took the load on its own for this flight . David, have you got nylon servo arms and are they ok, no hair line cracks. _ After reccovery, did you get normal control back. If during the climb you pushed the nose down to level off, and lets say one servo arm was bad for a while, the other has just gone, then a large down load might allow the arm to jump one spline. NOw when you release the down elevator the elevator would be one spline UP giving a large pitch up movement as the elevator neutral is way off now. During the fight to recovery from the spin, with large loads on the elevator might allow the splines to realign in the correct position. All this is speculation, but please check your servo arms and even try forcing them in either direction to see if the arms jump. Mine did, but only in one direction, not the other, worth a look. cheers tim
Posted on: 5/22/2012 3:09 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=11090034

RE: Bob Cat Copy Falcon 120 Jet
Hi david, sorry to hear of your incident, did you have 2 servos on the elevator or one. Have you had any Binding issues with your transmitter and receiver in the past. What are your failsafe settings, throttle idle, or off, controls all neutral? With positive uncommanded control commands like you describe, i would look at the radio gear. One area overlooked sometimes are the electrical connections at the servo leads. (they take a bashing and all mine are crimped and soldered now) Have you checked all your plugs to ensure that not one stray wire strand is exposed and could touch an adjacent pin . This has happened to me once and gave me a right wing down command, i was lucky to find it, if i hadnt i would have binned the whole radio set. with radio powered up, disturb ever plug and see if you get a lockout or uncommanded input How are your batteries in the receiver and the transmitter, have you fitted a new fuel pump or anything that could induce EMI interference to the radio. Cheers tim
Posted on: 5/21/2012 6:55 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=11088674

RE: Bob Cat Copy Falcon 120 Jet
Hi guys, just to add, I never had any probs with my standard servos that came with my Spektrum radio setup. The only issue I had, was my elevator servo arm, which was the standard nylon arm. After around 300 flights in freezing and boiling hot conditions, the splined part of my arm cracked and would allow only up elevator and not down elevator as the splines of the hub and arm rode up over eachother in one direction. It was my 7th flight of the day and i only found out, when i did a low inverted pass down the runway and the model would not respond to down elevator, to climb, roll up the right way and the elvator gave me up. When i came in to land the down elevator mix with full flap did not give sufficient and i slowed up too much and pancaked in from around 10 feet up. Every thing was fine except the U/C ripped out. I always give the control surfaces a wobble with my hand, before flight and did not detect anything. On the ground i pushed the elevator down and it was back driving the servo, so i thought radio failuer. In the evening i was stripping everything and investigating and fiound i could push the elevator in one direction and it did not back drive the servo. I then found the hairline crack in the arms hub. Note- i never ever use any form of loctite or glue on servo arms, it attacks the material. I would never have noticed this, even if i had 2 servos on the elevator, if one wasnt driving due to this condition, it would be maskeed by the other, until it failed as well. I will use ally arms in future. Just a thought, worth a look at your arms if they have done a lot of flying. cheers tim
Posted on: 5/9/2012 4:56 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=11074015

RE: Bob Cat Copy Falcon 120 Jet
post for the persil bottle fuel tank is here. I like the persil botle, much better materail than a coke bottle, less forward and aft movement of the fuel. I have used this same bottle for years in temps as low as minus2 and no cracking or splitting, also very light, cheers tim http://www.rcuniverse.com/forum/m_5913492/anchors_6460898/mpage_19/key_/anchor/tm.htm#6460898
Posted on: 2/1/2012 1:28 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=10938010

RE: Bob Cat Copy Falcon 120 Jet
Hi Tony, always more ways to skin a cat, here was old 90 degree bevel gear screw driver idea fro getting to the front bolts. I use ally boltsthroughout, they are so much lighter than steel, cheers tim http://www.rcuniverse.com/forum/m_5913492/anchors_8201738/mpage_81/key_/anchor/tm.htm#8201738
Posted on: 12/19/2011 10:21 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=10866612

RE: Bob Cat Copy Falcon 120 Jet
hI Tony, your can see the nose of the plane trying to pitch up when you are on the ground after landing. This is a phenonamon of the swept back wing. Your landing speed is a little high. Your nose is very high when the plane is sat on the ground, which makes things worse. I ripped off three nose gears for the same reasons, with uncontrolled pitch ups on landing. You fly from a lovely tarmac runway, you could reduce the high nose attitude on the ground slightly so the plane sits down better on the landing roll and still have good takeoff performance. Another way is use Crow braking, theres lots of info on this site, just do a search, I went a different root and made my nose leg extendable in length. Extended for takeoff then shortened for landing, works a treat and after about 200 landings, no tendancies of pitch ups. http://www.youtube.com/watch?v=dtVwtlhCXrE cheers tim
Posted on: 12/4/2011 10:22 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=10842634

RE: Bob Cat Copy Falcon 120 Jet
Hey Mat, sorry to hear about the loss of your falcon. Ref the Failure, did you experience any control surface (aileron or Flap) flutter, which subsequently ripped the wing apart. Any signs of distress to the aileron or flap servo arms or control surface horns. what size control rods were you using, any flex in any of the control runs. At really high speed, flutter will rip any wing apart no probs, or tear the control surface off in an instant, just a thought. cheers tim
Posted on: 9/22/2011 2:18 PM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=10729386

RE: Bob Cat Copy Falcon 120 Jet
hey bud, as per the previous reply, check the nose is slightly high when it is on its wheels. If not, you can put packers under the nose retract mount but the wheel wont fully retract then, but will be fine for a test flight. Check your engine down thrust (upthrust), if the rear of engine is pointing down more than a few degrees, then it will be pushing the nose leg down hard during take off. You could take a degree of down thrust away, again use packers under the engine mount. Try reducing your fuel quantity, how much do you carry, try a 3/4 full tank and fly for say 5 mins, at least you will be airboune and see how she flys. You could try a small amount of flap, although i didnt see any benifeit at my field, but others do, worth a try. Are your wheels large enough for rough ground, small wheels will dig in, i use large wheels. are the wheels free, and if brakes are fitted, are they releasing properly. Check your c/g , too nose heavy will hinder rotation. All the best tim
Posted on: 8/7/2011 2:20 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=10659140

RE: Bob Cat Copy Falcon 120 Jet
Hi Ray, the tubs look great, can you ship to UK and does anyone in Uk want one, we could bulk buy to save shipping cost, please reply here, cheers tim
Posted on: 7/28/2011 3:00 PM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=10643692

RE: Bob Cat Copy Falcon 120 Jet
On youtube it states, a P60 SE and fully glassed airframe. cheers tim
Posted on: 5/1/2011 12:04 PM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=10494885

RE: Bob Cat Copy Falcon 120 Jet
Really great flying Paulus, its amazing how close in you can fly the falcon, thanx for sharing Tim
Posted on: 5/1/2011 12:00 PM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=10494265

RE: Bob Cat Copy Falcon 120 Jet
Hi kevin, I carry a CO2 tyre inflator for Bicycle tryes in my pocket, It will extinguish a fire and will blow over an engine if required, they are cheap and available from bike shops. Do not use the very small nozzzel it is very visious, unless you are blowing the engine over. cheers tim
Posted on: 4/20/2011 4:50 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=10473980

RE: Bob Cat Copy Falcon 120 Jet
Hi Paulas, Very nice, amazing you have kept the weight down, with all your mods, i think mine comes out at around 7kgs dry, but with heavy home made jet. The standard engine setup normally points down (playing it safe here, no mention of upthrust or down thrust), about 5 degrees not 7, but others have the engine mounted striaght. With 7 degrees the nose is being pushed down on the take off run, a reduced angle might assist takeoff performance. Also the nose does need to be slightly high when sitting on the ground to get off quickly, which is why i built the extending nose leg, great for take off on short grass strips, then reduce leg length for landing, it sits down positively during the landing roll out. You have put in a lot of work over 6 months to get the result you were looking for and you must be very pleased. I personally like the black/white and the orange/white standard colour schemes, i think they really set the lines of the plane off well. For prospective buyers/flyers and those new to turbine flying, the Falcon can be built very rapidly, my fastest is 1 week, while working away from home in a hotel room, from start to flying. There are some basic things to check like glue joints in critical areas and the nose gear and wing gear mounts ( same as any other ARFT) and the model will fly well as standard in a scale like manner, not unlimited G senario. If you need the out and out performance and high G flying, then maybe re-engineering is the way to go. kind regards Tim
Posted on: 4/19/2011 1:13 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=10471516

RE: Bob Cat Copy Falcon 120 Jet
hey jetster, I live in maidenhead, where do you live, cant pm you, e mail me tim777jet@hotmail.com. maybe tie up, cheers tim
Posted on: 3/17/2011 2:04 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=10405357

RE: Bob Cat Copy Falcon 120 Jet
hi Mike, the plane was designed as a pusher prop design. We fit a jet and fly energetically, but you have to be realistic. I have seen some guys on youtube pulling G, i would never do, the plane stays together. How much strengthening they do I dont know. I saw recently some footage I think from China or the Philipines, where they fly from roads. I think it was '2 falcons racing' , they fly flat out pretty much, dont know what engine they use, but climb after takeoff is impressive, theirs stay together. I read the JET International magazine. I an Amazed by the reviews of new built kits which cost a fortune. During the build they find leaking rams, useless pipes, they always seem to modify something, then they fly them and a fair few crash, due to structural failure. As I recall, one had a tailplane half (of an all moving tailplane) which wasnt attached inside correctly, Crash, Undercarriage mounting plates seem to too weak. There seems to be so many failings with these exspensive kits which not not exist. I can build a Falcon in week, I have done it in my hotel room, with minimal tools, these expensive models with high degree of completion also seem to take a long time to build. So all in all, £185 well spent for a model, in my book. Just fly sensibly cheers tim
Posted on: 3/7/2011 2:59 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=10383856

RE: Bob Cat Copy Falcon 120 Jet
Another idea here http://www.rcuniverse.com/forum/m_5913492/mpage_145/key_/tm.htm
Posted on: 1/23/2011 1:58 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=10281851

RE: Bob Cat Copy Falcon 120 Jet
Hi Pubhi, I have no experience with ducted fans, but the legth of the exit tube must be quite important to obtain max thrust. Do you know the exact length and outlet size that gives best thrust. In a scale setup the fan/motor unit will be buried in the fuse but on the falcon, you dont need any exit ducting. Have you tried thrust test with no or very small ducting as comparison. Also have you tried with no inlet ducting, it might be very important, but then again maybe not, worth a try to save a lot of time. The long rear ducting could be supported with a link from the tailplane if absolutly necessary. ref your strengthening ally strips on the lower fuse, this is a good strengthening idea in that area, but on my second falcon, i never strenghtened it, it was fine, with my really heavy home built jet on the back. My first one only cracked after many many flights and heavy arrivals, so with your light setup, i dont think you need it. You will need to save as much weight as possible, so could save weight there. Best of luck with your project, cheers tim
Posted on: 1/21/2011 12:30 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=10277603

RE: Bob Cat Copy Falcon 120 Jet
Hey Kobra, great flight and video, especially in the freezing conditions, my fingers kill me after 4 or 5 mins, getting old i suppose. Great EDF version, thanx for sharing, cheers tim
Posted on: 12/1/2010 4:58 PM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=10170310

RE: Bob Cat Copy Falcon 120 Jet
Model comparison and my next step Dont want to deviate on this forum, but I still havnt progressed repairs of my Falcon since my heavy landing a few months ago, just too busy. Anyway, was going to modify the Falcon with a redesign to remove the 2 booms. Options are an F15 style back end or something like a Gruman Panther. Just seen in the model magazines the YT international Pantera, designed for our size engines. Gave them call for some specs. Specs are similar to the Falcon, wingspan 66inch, length 80inches, weight dry 18pounds. They are not making an all moving tail now and the main retracts have to have the cylinders on opposite side to ours. Price preproduction £680/post production £780 In comparison, the falcon is 15.4 pounds dry, so lighter. The falcon fits in a car well, as the booms reduce the overall length of the fuse dramatically. ThePanera can be built with removable nose though. I offered up a single boom/fin assembly, central on the falcon fuse last night, and she looks really great. I am toying with the idea of making a slide on rear fuse section, which would pick up on the front and rear spar mounting holes and have an extra mount bolt at top of fuse close to the engine for added support. Two side intakes to direct air down to the engine, coverng most of the engine and use the same section tailplane, mounted in the fin area as it is now. My booms were undamaged, but dont think they would be strong enough with just one supproting all the loads. A complete new back end would be needed, but in the same fin shape as original. The saving in weight of one boom, would be offset by the additional rear section build. As only one servo for one rudder required, little weight saving here. The elevators could be powered by 2 sevos idependantly or one for weight saving. The slide on rear section would make transporting easy as it is now, slide in position, push front and rear spares through, tighten one top mount bolt and connect 2 servo leads. No loss of thrust through a tailpipe. Any ideas/ sugestions, really busy and working away alot, but will try to start in next week or so. Cheers tim
Posted on: 10/15/2010 6:54 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=10069854

RE: Bob Cat Copy Falcon 120 Jet
Hi Tom, as far as i can remember, only one occurance where a wing had distress in flight, i think the plane got down ok, but i recall the plane had previously had a heavy landing and had struck that wing, so could have been over-stressed prior to this incident. With a Jet Joe, that should be a good size engine for the plane and if flown reasonably, should be fine. Never had a problem with my home built 14Lb thrust engine. Anyone else know of any failures, Cheers Tim
Posted on: 10/15/2010 6:31 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=10069836

RE: Bob Cat Copy Falcon 120 Jet
The mini axial flow gas turbine engine looks very interesting. As to date, i have not seen a mini axial flow engine running. I tried to design and build one in the 90's, I went to small and with losses at very small sizes, it was destined to fail. I made 6 stages of compressor, and had 2 stages of Variable Inlet Guide vanes and 2 bleed valves. The engine did show promise and would accelerate to around 40,000 rpm but then would fizzel out. I am an aircraft engineer by trade, my main engine at the time was the trusty RB211 524 and so I overcomplicated things, went back to Centrifugal compressors in the end. There is a very clever chap, who is actively involved with the GTBA and he has made an axial flow turbine, which would fit in our planes. The engine has been complet for a few years, but he was waiting to have full instrumentation before starting it up. The engineering in it is mind blowing, every bit built by hand, nothing short of outstanding, an outstanding engineer. Sorry to digress, cheers tim
Posted on: 10/7/2010 3:58 PM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=10054089

RE: Bob Cat Copy Falcon 120 Jet
Not sure why anyone would want to exchange a beautiful swept wing for a plank. The falcon wing is a really good design, it is very forgiving and provides lots of lift. The model looks scale like and purposefull on the ground and in the air. Inverted flight is no problem either, each to their own i suppose, a little confussed though!
Posted on: 10/7/2010 10:37 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=10053608

RE: Bob Cat Copy Falcon 120 Jet
Hi dave, ref the nose high attitude. If you make your nose leg longer, the wheel probably will foul the plywood radio gear plate just rear of the nose gear bay. If you cant get a larger wheel on, then simply put a spacer under the retract mount. This way you can still use your existing set up and the wheel will stow away. admittedly the leg will be slightly protruding when fully retracted, but make no difference. I used all the gears from my first falcon, and found when i fitted them to the later falcon, the nose was not high enough for good take off, design must be slightly different. I fitted large spacers under the nose, about 12mm and gives me beautifull effortless takeoffs and no hacking the plane to bits. On the front of the spacer area, why not fit an ultra brite LED FLYING light, stays on all time, really good for orientaionon dull days. Cheers Tim
Posted on: 9/9/2010 6:40 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9990053

RE: Bob Cat Copy Falcon 120 Jet
Hi Dave, you hit the nail on head. Better off with the nose sitting slightly high on the ground not pointing down. There is no propwash so elevator is ineffective until near take off speed is attained. By then you are hauling the nose up, just as the elevator gets some bite. With nose slightly high, she rotates silky smooth almost on her own. Cheers tim
Posted on: 9/5/2010 4:51 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9981319

RE: Bob Cat Copy Falcon 120 Jet
There is info on this site ref EDF conversion, somewhere, try the search engine. Also, just put in falcon 120 EDF into youtube.com, lots of videos there. One guy had a tailless conversion with EDF and flys amazingly well, brilliant work. Cheers tim
Posted on: 9/2/2010 3:42 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9975569

RE: Bob Cat Copy Falcon 120 Jet
Hey, Chris, brilliant flying and i must say, full marks to the camera man as well, those pictures are truely fantastic. Just in passing, do you know what camera was used and what settings, cheers tim
Posted on: 8/31/2010 2:22 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9970942

RE: Bob Cat Copy Falcon 120 Jet
Ok guys, bit of help required, Following my firm arrival and removal of my main gears for the wings, a couple of weeks ago, I have been scouring the internet (whilst working away from home) to see if there is any other model suitable for a 14 lb turbine that will perform off a grass strip. I have always liked the F15 and F18, but I fear they will be too heavy and not sure how the take off performance and landing performance would compare to the Falcon. I cant source a replacement falcon in Uk at moment, possibly could get hold of a white one with blue stars on it, not sure what it would look like in the flesh though, has anyone seen this colour scheme in the flesh, any pictures?. I think I may repair mine, retain all the fuse and wings, but modify the rear end, do away with the booms, to have two seperate stabs and twin fins, like the scale jets, but it is an unknown and a bit risky if i get it wrong. can anyone tell me where i can get hold of the Orange, Blue and White covering to match the original covering of the Falcon, in the UK. I have searched the threads, and found refereence to ECONOKOTE, SIG AEROKOTE, ULTRACOTE and MONOCOTE. as anyone used any of these products and confirmed a match, if so is there a ref number so i can order some. Kind Regards Tim
Posted on: 7/17/2010 9:03 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9870492

RE: Bob Cat Copy Falcon 120 Jet
Hi Stacey, yes, know where you are coming from, upthrust or down thrust was a debate a while back. I always called it downthrust, now i go with the flow and call it upthrust. As long as our engine exhausts are pointing downwards towards the ground, then thats good. Nice signature picture by the way .Cheers Tim
Posted on: 7/17/2010 4:05 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9870301

RE: Bob Cat Copy Falcon 120 Jet
Hi Dave, yeh, looks about right, bit hard to see from picture, but if you run a straight edge along bottom of tailplane and align the bottom of elevator, this is WRONG. The elevator should alighn with a straight edge run along the top of the tailplane profile, as it appears in your picture. Ref mixing, I do not use crow, cant comment, but with flaps full down, you need a bit of down elevator to fly straight and level, but i fly with 4 to 5 degrees of upthrust on engine cheers Tim
Posted on: 7/16/2010 6:40 PM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9869558

RE: Bob Cat Copy Falcon 120 Jet
Hi Erazz, some great flying there, getting in the groove, looked just like mine a few days ago. Your engine mount system looks agricultural in approach and obviously works well. Ref the compressor, they are really resilient to abuse, but obviously the balance might be an issue now. Usaually if out of balance, the engine noise changes and becomes loader, usually with a shrill. If out of balance it will impart a larger than normal load on the shaft and bearings and is not recomended. Obviously you have much turbine experience, but would rather replace the compressor, not sure of price for yours, but the KKK2380 is around 85 pounds and easy to change, although again balancing is recommnended as the compressor wheel manufacturers balancing, which is done when the wheels are made, is not as accurate as the model jet engine manufactures tolerances. Anyway, some great flying what an awesom machine the falcon is. I am thiinking hard about modding my damaged falcon as stated previously, just to change its look into a more scalish fighter look, but retain the excellent flying and short field capabilities. I see some guys have gone tailless with their EDF conversions, now is a credit to those guys, experimenting with expensive kit, when anything could happen, full marks, cheers tim
Posted on: 7/5/2010 8:32 AM by Author "tim777jet" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9845436