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I'm building the TopRC F9F Cougar

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Old 07-10-2017, 04:34 PM
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Default I'm building the TopRC F9F Cougar

Hi, I'm building the TopRC F9F Cougar. I've searched here and can't find a turbine build thread on this jet. I'd like to know other's experience with it. On RC Groups, there's one build on the EDF version. But I'd like to hear what others have found with the turbine version.
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Old 07-10-2017, 06:32 PM
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TimD.
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I purchased the turbine version as well. I just have not had time to do anything with it yet. If it is as good as their Warbirds then it should be a WINNER !!
I bought the Robart electric retract set for it.
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Old 07-10-2017, 06:54 PM
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Originally Posted by TimD. View Post
I purchased the turbine version as well. I just have not had time to do anything with it yet. If it is as good as their Warbirds then it should be a WINNER !!
I bought the Robart electric retract set for it.
what size turbine are you putting in your Cougar?
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Old 07-10-2017, 07:19 PM
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I have a couple of 60n engines lying around so one of them. A friend had a Skymaster one same size with a 100n in it , I thought it was over powered.
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Old 07-11-2017, 06:14 AM
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Originally Posted by TimD. View Post
I have a couple of 60n engines lying around so one of them. A friend had a Skymaster one same size with a 100n in it , I thought it was over powered.
Over powered? Blasphemy!
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Old 07-11-2017, 01:21 PM
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LOL

In fairness, it was pretty robust.
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Old 07-12-2017, 08:49 AM
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I ordered a Kingtech K80 for this plane. It hasn't arrived yet. The factory is quite busy. I think it will be the perfect size and balance between weight and flight time. I have to say this plane is really well built. The parts are impressive for the price. The newer Kingtech engines have auto-start, and run on diesel fuel. I have another KT engine running on diesel and the flight times are longer, better fuel economy, and more power too. Diesel has higher energy density than kerosene. But then are more smokey on cooldown. It sometimes freaks people out.
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Old 07-13-2017, 08:35 AM
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I have about 5 flights on mine with a K 100. It needed nose weight to balance even after removing some of the ducting and moving the engine forward up to the fuel tank. More power than it needs. I would go for the new K70 if I buying a new turbine. Suggested aileron throws were way too high for me. I have some of my plywood delaminating inside. Thee dealer said he would take care of it. I'm waiting on a reply from Top Model. Other than that, I'm happy with the model.
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Old 07-13-2017, 09:10 AM
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Thanks for the info. It's good to start getting some feedback on how this jet build and performs. Couple questions, what was your final weight dry, and equally important where is your CG? The manual's CG location diagram can be interpreted a couple ways. Like, on this jet, as measured right next to the fuse or at the detachable wing root location yield very different cg's.
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Old 07-13-2017, 09:24 AM
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It's right at 20 pounds. I know what you mean about the CG. I debated which way to measure for awhile. Problem is, I don't remember. I did mark it, and will get you an answer next time I get inside my trailer.
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Old 07-13-2017, 02:53 PM
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In an effort to clear up the CG confusion I scaled the known CG location of a Skymaster to this size jet. That location came out about 1 inch aft of top RC's. Then I used a nifty online CG calculator and it pretty much agreed with Skymaster. Top RC's position is a more conservative approach so the difference probably isn't a problem per se. The huge trailing edge webs that extend aft to the tailpipe throw the center of lift back a lot, so that supports the Skymaster location. Heck, I'll probably split the difference. I have a new K80 engine on order.

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Old 07-14-2017, 04:04 AM
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Here is my interpretation of the cockpit......
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Old 07-14-2017, 07:53 AM
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Did it really say "Ejectiom" Seat?
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Old 07-14-2017, 09:26 AM
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Originally Posted by Bob_B View Post
Did it really say "Ejectiom" Seat?
yes it did! I did what I could with it with a sharpie. Also, the RESCUE arrow on the other side I has upside down lettering!

ya gotta keep to the big picture, the jet has amazing quality for the money.
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Old 07-14-2017, 09:27 AM
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My favorite was a canopy on one of those ARF's that said "Lift Hear"
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Old 07-14-2017, 10:02 AM
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A buddy has the same plane but I have yet to look at the lettering, it's all good! The jet flies great on E Power too.
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Old 07-14-2017, 11:30 AM
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Someone should check the pilot for a tattoo that says " No Regerts" Ha!
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Old 07-15-2017, 02:18 AM
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A buddy of mine has the ziroli panther, straight wings. But the plane is almost the same size otherwise. The plane sits on the ground nose high. This is normally a no no for rc planes as it leads to landing bounces, relaunch, and porpoising. So I warned him about it prior to maiden. Sure enough, that's what happened. Of the various landings, the best were the ones where he killed the flaps upon touchdown. So, how to avoid this on mine....gears turning. I've done this on other jets to great results, but none sat on the ground quite this badly. So I programmed in what's called CROW, or reflex ailerons with the last notch of flaps. The idea is to raise both ailerons up about 3/8" in a mix with the last notch of flaps. Aerodynamically, this does two things. It prevents or delays tip stalls, and it kills some lift to prevent the wing from taking off again once the nose gear touches down. The sequence is something like this: you approach to land with the first flap setting and no CROW. You're generating a lot of lift with those flaps. On short final, switch to full flaps. At that point most of the flaps are just drag, not much more lift. the ailerons go "CROW" killing some lift, and at the same time the pilot will transition to high alpha nose high attitude to get that lift back and pick up some more drag, and keep the descent rate the same. Upon touchdown, as the nosegear touches, the main wing angle of attack lowers, reducing lift. At that point, the reflexed ailerons have also killed more lift. The combination hopefully keeps the jet stuck. The two key timing jobs for the pilot is to flip to full flaps about 100 ft out, and 25 ft up, and to go high alpha gradually right after that. The turn to final should be about 50 mph if one has a gps or pitot speed sensor. My last jet has a Futaba GPS sensor with voice reporting, and this key piece of info helps to set up a stable approach more consistently. I've seen more jets crash on landing than anything else so I do a lot of thinking about this part.
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Old 07-15-2017, 02:33 AM
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Just finished my nose gear door mechanism, which i'll share here with this Youtube video. Things open and close rather more quickly in this video than what really happens in flight because I'm using an air hose to apply the pressure. When using the air tank and Robart valves, the gears and doors open and close much slower, but no less reliably. By the way, when you buy the retracts from Caiman Distribution, you pay one price and get an unexpectedly huge box of stuff. It is VERY extensive and complete for the money. Impressive to say the least.

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Old 07-15-2017, 04:12 AM
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I've got the skymaster version and it has no issue landing with the nose high attitude. It's getting a re paint underneath after I had a flame out on its 5th flight and damaged the bottom of the fuse. Overall it is a great plane to fly and very stable. My flaps don't hit the ground either when landing but agin this is the SM version so different struts.

I also removed my inlets to drop in a larger fuel tank for the VT80.

Got some build pics on my page www.facebook.com/aussiejets

Just browse the albums. For the cougar build

Here is a video of flight 2


cheers

Jeremy

edit- updated link to correct Facebook page

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Old 07-15-2017, 07:10 AM
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Great landing! No bouncing, etc. You're right. slows down faster on grass, too. The bouncing I saw was on matt. What's the weight of yours, and where is the CG?
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Old 07-15-2017, 09:57 AM
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Nice Jeremy!
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Old 07-15-2017, 01:45 PM
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The dry weight was just on 8.7kg

my CG is as per the image. This is from a build thread over in rcgroups large edf section. Seems to be fine here.

I've finished the re-paint on mine now. Has a nice two tone scheme
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Old 07-15-2017, 07:18 PM
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Thanks for the info on weight. Mine will come in at around 21 lbs I think. This brings me a a subject that could maybe save some people some financial inconvenience if they read this. I read the websites and the manual for this TopRC Cougar, and they said the plane's flying weight was 15lbs, and the turbine was in the 6kg range. This engine matches that weight and the jet uses foam core composite which is quite light, so nothing seemed wrong to me at the time. As the plane progressed, I noticed the engine mounting rails were much farther apart than the specs for a 60N engine, suggesting a bigger engine was intended by the designer. And I started talking to people who had built the Ziroli Panther and the Skytmaster Cougar, it started dawning on me this jet cannot possibly come in at 15lbs. I bought the jet from Caiman Distribution so I called them with my concerns that someone could buy the wrong turbine if I'm right, and wreck the plane or worse. To Caiman's credit, they agreed to research this issue. They got back to me recently that they agree the info can mislead a builder, and the flying weight is understated. They've begun the process of changing the websites and brought the issue to the attention of TopRC. I've been told TopRC has already changed the cover of the manual that says 15 lbs flying weight. I can't say enough good things about Caiman Distribution. The Cougar has great quality in the build, I got a good deal, the retract, strut, & brake kit they sent had so much included my mind was blown. There are no gaps between the formers and the skin, and there is glue everywhere there should be. Nothing is perfect of course, and the nose gear door closer is not refined enough to be used. Also, a couple decals have misspellings or are upside down. Really, no big deal. Get an engine that can produce 80N force. And buy from the guys with integrity, Caimandistribution.com.
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Old 07-16-2017, 05:28 AM
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Chris Gunner's son is flying an Extreme Jets Cougar (as stated above, basically the same airplane) on a Kingtech K45 engine - 9.9 lbs of thrust. It has a bit of a longer takeoff roll, but it flys *great* on that engine.

You do *NOT* need a 1-to-1 thrust to weight ratio in an aircraft to fly well - after all, the real Cougar had thrust equal to around 1/3 of its weight...

That being said, if you look at the specs of the newer 80N engines, namely the Bee 80 and Merlin VT 80, they are very close to the size and weight of the newer 60N engines like the K60. However, their fuel consumption is quite a bit higher. There are tradeoffs, but you don't *have* to have an 18 lbs thrust engine to fly this plane...

Bob
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