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Bob Cat Copy Falcon 120 Jet

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Old 05-30-2008, 02:52 PM
  #1151
sweetpea01
 
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Default RE: Bob Cat Copy Falcon 120 Jet

I wouldn't think Velcro would hold on at 150mph......that is a thought though
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Old 05-30-2008, 03:41 PM
  #1152
noahb
 
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Default RE: Bob Cat Copy Falcon 120 Jet

well, just flew it again. Clocked it on a hand held radar unit.

Comming out of a small dive and letting it level off and flying 100-200 feet before clocking it, the speed measured was 145 mph.

Straight and level flight was clocked 134mph.

This is with a 14lbs super bee.

I am sure if I dived it and leveled off that it would be closer to 160 tops.

however avg straight speed is shown to be around 125-135.

Keep in mind that even though the design is clean, it has very thick wings, thick booms, and no gear doors.

I am happy. Actually, I thought about getting the Rabbit myself, but not sure that I want to push this much faster. The verticle is great, could use more thrust, but it carrys verticle speed very well and it pretty much climbs higher then I should be flying. However, it would be nice on take off to point it straight up and bam...out of sight.

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Old 05-30-2008, 07:42 PM
  #1153
sweetpea01
 
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Default RE: Bob Cat Copy Falcon 120 Jet

Quote:
ORIGINAL: noahb

well, just flew it again. Clocked it on a hand held radar unit.

Comming out of a small dive and letting it level off and flying 100-200 feet before clocking it, the speed measured was 145 mph.

Straight and level flight was clocked 134mph.

This is with a 14lbs super bee.

I am sure if I dived it and leveled off that it would be closer to 160 tops.

however avg straight speed is shown to be around 125-135.

Keep in mind that even though the design is clean, it has very thick wings, thick booms, and no gear doors.

I am happy. Actually, I thought about getting the Rabbit myself, but not sure that I want to push this much faster. The verticle is great, could use more thrust, but it carrys verticle speed very well and it pretty much climbs higher then I should be flying. However, it would be nice on take off to point it straight up and bam...out of sight.

I put myself on the list for the rabbit so the turbine could be used on my next plane (that should be shipping soon). I'll keep my straight and level passes below full (at least sometimes). Glad you got those high numbers and its holding up.
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Old 05-31-2008, 12:48 AM
  #1154
noahb
 
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Default RE: Bob Cat Copy Falcon 120 Jet

thanks.

I would like to get a rabbit as well. I am hoping to sell one of my super bees to help fund one.
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Old 06-04-2008, 10:38 AM
  #1155
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Default RE: Bob Cat Copy Falcon 120 Jet

I will be using 700 Spring Air retracts. Are these ok? I think some where on here someone said NOT to use spring down unless you have it retract up??
Thanks.. If thats the case, then I will go with Robart 550 retracts and 7/16" strut! Are you guys using pull pull for the steering OR direct linkage for the steering?
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Old 06-04-2008, 10:42 AM
  #1156
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Default RE: Bob Cat Copy Falcon 120 Jet

I use the 700 series and love them. They are not hard at all to setup. The front retract actaully has a pretty strong spring in it and I have very little slop if any in my wire and have no issues what so ever. Even if I drop the retracts at half speed, it locks down just fine.

I put the steering servo in the servo tray and ran wires directly to the front retract.

I will see if I can post a few pics a bit later.
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Old 06-04-2008, 10:48 AM
  #1157
sweetpea01
 
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Default RE: Bob Cat Copy Falcon 120 Jet

I'm going to use the Airpower retract and the Robart trailing link 7/16 struts.

Interested to see your install pics of your gear though.
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Old 06-04-2008, 10:54 AM
  #1158
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Default RE: Bob Cat Copy Falcon 120 Jet

Thanks!! Pics would be greaaaaaaaat!
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Old 06-04-2008, 11:19 AM
  #1159
noahb
 
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Default RE: Bob Cat Copy Falcon 120 Jet

here are the pics.

Not the best install, but it works great and it was simple to setup. I did not look forward to setting up the nose retract, however it turned out really simple. I did have to "remove" some wood off the mounting blocks as the little crimps I used need an area to recess down in. However, if you had some kevlar thread or something like that, you could just tie on the end and then glue the knot and you would be fine I think. It took me about an hour to mount and hook up the servo. The part of the wheel cover missing is my fault. The plastic they use if very brittle and I broke off the end right there triming it. So I trimmed it back some.

also, I used string and tied a "Ty Wrap" between the two wires as shown. This keeps tension on the wires at all time, even when retracted and prevents them from snagging on something and causing the front retract to hang up.
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Old 06-04-2008, 11:20 AM
  #1160
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Default RE: Bob Cat Copy Falcon 120 Jet

For those who are considering / already have the Airpower 250 retracts have a look at these by Digitec:

http://shop.digitech-turbines.com/pr...jqq89jvuo1m396

I changed my Airpower Oleos for these and they work well with the Digitec trailing legs.

Some adjustment on the wheel wells but nothing too hard.

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Old 06-04-2008, 11:26 AM
  #1161
noahb
 
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Default RE: Bob Cat Copy Falcon 120 Jet

that is a very nice set.

I actually used 3/8" robart struts for my mains. The ones I had on hand were a knock off of Robarts. I had to make an adapter to extend the retract about 1.5 inches. However, these were not robarts and had lots of slop in them. So I had some F-16 Tam struts laying around. I took the block off the end as it's angled for the f-16 and I made a aluminum block, installed the axles and so far they look to be very good struts.

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Old 06-04-2008, 11:58 AM
  #1162
sweetpea01
 
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Default RE: Bob Cat Copy Falcon 120 Jet


Quote:
ORIGINAL: Speny

For those who are considering / already have the Airpower 250 retracts have a look at these by Digitec:

http://shop.digitech-turbines.com/pr...jqq89jvuo1m396

I changed my Airpower Oleos for these and they work well with the Digitec trailing legs.

Some adjustment on the wheel wells but nothing too hard.


a little pricey with the exchange rate right now on the US dollar. They look nice though. I'll keep them in mind. I have not bought my retracts yet.....was waiting until next month (after I move)
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Old 06-06-2008, 03:52 AM
  #1163
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Default RE: Bob Cat Copy Falcon 120 Jet

On my 59th landing, i damaged my nose leg and ripped the L/H main gear assbly out of the wing. Made lovely smooth landing and during roll out model rolled down a small dip in the freshly mown grass and model became airbourne nose high, ran out of airspeed and dropped like a stone on the nose and left wing gear. I have repaired the the wing, very little damage and replaced the rear undercarriage bearers which split in half. The front bearers were perfect, just glued them back in. The euro kit front retract, had the pivot pin bent and this tore through the pins mounting hole. This is good, as it acts as weak point and saves damage to the fuselarge. Again 1 hours work machining up to bushes to repair the torn side of the unit, and all back flyable again.
Now i think my problem is that the I increased the length of nose leg to aid take off on the rough grass and think this is instrumental in lauching the model again if i hit a bump in grass during roll out, so will reduce it for next flight and see how i go
i have a cunning plan though, so read next post.
By the way, i tried three takeoffs from a tarmac strip, what a difference, bit of video below, the first attempt i held her on the brakes and manged to get throttle quite high up, and she accelerated really well and off in a short distance. The first bit of video is my second attempt without brakes and the second vid is with brakes on but didnt hold as well the first time so not quite as spritely.

www.youtube.com/watch?v=OacIksQgw1E
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Old 06-06-2008, 04:01 AM
  #1164
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Default RE: Bob Cat Copy Falcon 120 Jet

Now my nose gear is a beautiful piece of engineering, but one problem, is that there is no damping only a spring, which doesnt help matters when hit a bump. I have thought for a while of making up a damper. I tried to find a model car damper that would fit inside my leg, but they are all too large in diameter (10mm, but i need 6mm max).Anyone know of a smaller one?
I have seen that Eurokit make a dampened leg and Flyeaglejet sell their models with damped legs.
So back to workshop and i made this
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Old 06-06-2008, 04:58 AM
  #1165
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Default RE: Bob Cat Copy Falcon 120 Jet

The damper has 1.5mm rod attached to a brass piston at the bottom. The piston has 4 small holes @ 0-8mm, to allow the oil to flow through, these are a bit small and i should have opened them up. The holes are drilled randomly on purpose. There is a flutter plate on top of the piston and this is lightly loaded with a spring. As the piston moves down the oil is pushed through the holes and lifts the flutter plate, escaping to the other side of the piston. When the piston is now pulled back the other way, the flutter plate under spring pressure seals the holes, restricting the oils ability to flow back. Therefore the leg should compress quickly, but extend at a slower rate.
I had to guess the thickness of oil to use, but settled on 20/40 engine oil. The unit was filled with oil and the piston inserted, then the end cap (containing 2 miniture o rings) was pressed on. I then soldered on a brass endcap to the 1.5mm rob, which is threaded at the top to accept a 10 BA screw to attach the damper to the top of leg. The main body of the damper has a hole drilled right through it and picks up on the leg pivot pin.
I found another spring which just fits perfectly over the damper and inside the leg.
I assembled the model for a test and the dampers effectivness is obvious, works a treat. I ran out of time, before returning to work abroard, so will have to wait for a few weeks to try it out.

Just a note;
- the flutter was to be drilled with one hole to allow the oil to escape quickly to the top of the damper during compression, but when i tried it before assembly, it seamed good as it was.
- the flutter plate should have a stop postioned above it, to limit its movement as the spring is probably not strong enough to force it against the resistance of the oil, to quickly shut off the holes in the piston as the leg extends, reducing its dampening effect.
- It is hard to tell if the leg extension is slower than compression, only a flight test will tell to see if the model sticks to the ground with out bouncing, but i think even a piston travelling in oil with no flutter plate assembly would be better than just a sprung U/C.
- To help the model stick to the ground better, i had thought of using a small undercarriage phnematic door cylinder pulling a cable attached to the bottom of the leg, to pull the leg up @ 8-10mm to reduce the length of the nose gear, but leaving enough suspension travel and reduce angle of attack when the model lands. Linked to the landing position flap setting, this would give short nose leg for landing and long leg for take off. I think some military jets use this idea.
- due to the 1.5mm rod being attached to the top of the piston, the area of that side will be less than the bottom (unequal area pistons) so this will offset some of the effectivness of the flutter plate. ( if no flutter plate were fitted, due to different areas of piston, the leg would compress slower than when it extends, which is the wrong way round)

Cheers Tim
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Old 06-08-2008, 01:26 AM
  #1166
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Default RE: Bob Cat Copy Falcon 120 Jet

I'VE LEARNED ALOT READING THIS FORUM , I JUST BOUGHT THIS PLANE THE FALCON 120 AND I'M PUTTING A RAM 750 ON IT WHICH I JUST PURCHASED . THIS IS MY FIRST JET AND DIDN'T WANT TO SPEND A LOT OF MONEY FOR A JET IT BEING MY FIRST ONE. AFTER READING THE FORUMS ON THIS PLANE IT LOOKS AS THOUGH I MADE THE RIGHT CHOOSE.
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Old 06-08-2008, 01:08 PM
  #1167
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Default RE: Bob Cat Copy Falcon 120 Jet

flew again today. Had smoke this time.

I had about an 8 to 10mph tail wind and clocked it coming out of a medium dive. It hit 168mph.

here is a pic of the smoke.
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Old 06-08-2008, 01:31 PM
  #1168
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Default RE: Bob Cat Copy Falcon 120 Jet

I got the motor mounted. I thought the big Ram 750 would look goofy with a big high metal mount, so I tried to streamline things a bit by dremeling out the center section of the motor mount and adding some hard wood to the sides to mount the motor too.

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Old 06-08-2008, 07:30 PM
  #1169
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Default RE: Bob Cat Copy Falcon 120 Jet

Noahb,

That is one cool shot. Glad you got the smoke on. Have my Falcon coming and will be here about Thursday. Been thinking about one of these for a year. After reading all of the post here just can't stand it no more!!! What angle did you wind up with on your engine?? Later.

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Old 06-08-2008, 07:51 PM
  #1170
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Default RE: Bob Cat Copy Falcon 120 Jet

My falcon arriving soon. It is at the custom office now. Anxious .....
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Old 06-08-2008, 08:02 PM
  #1171
seravios
 
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Default RE: Bob Cat Copy Falcon 120 Jet

wow....that is equivalent to 270km/hr
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Old 06-08-2008, 08:02 PM
  #1172
sweetpea01
 
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Default RE: Bob Cat Copy Falcon 120 Jet

Quote:
ORIGINAL: noahb

flew again today. Had smoke this time.

I had about an 8 to 10mph tail wind and clocked it coming out of a medium dive. It hit 168mph.

here is a pic of the smoke.

Do you have a pic of your smoke tank setup?
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Old 06-09-2008, 05:44 AM
  #1173
noahb
 
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Default RE: Bob Cat Copy Falcon 120 Jet

I have my turbine setup at 5 deg. of down thrust. It's about perfect.

I will take a picture this evening of my smoke setup. I put the pump in the very back of the jet as I needed more weight back there anyway. However, I use a 16 oz. nygene (sp?) sq. bottle that I installed some fittings on and put that right in front of my main tank.
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Old 06-09-2008, 02:14 PM
  #1174
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Default RE: Bob Cat Copy Falcon 120 Jet

I am re-covering the bottom to give it more contrast? What do you think of this scheme I did on Paint over top of a BVM Kingcat.

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Old 06-09-2008, 02:33 PM
  #1175
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Default RE: Bob Cat Copy Falcon 120 Jet

Tumbler, where did you get that FOD Screen? Ive been looking for 2 screens for a pair of ram 1000's.
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