I'm building the TopRC F9F Cougar
#81
Join Date: Nov 2003
Location: Mexico CityD.F., MEXICO
Posts: 253
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Maiden mine last week with a Bee 80
I was worried about power because I'm flying over 7000 feet of altitude, and we lost 30% of the nominal thrust here
I ended up fliying at half power most of the fligth and only whent full power for take off, verticals and a couple of high speed passes
Great plane overall and only modification was to the fuel tank, I moved the stoper to the center of the tank so the clunck can go all the way up and down
I was worried about power because I'm flying over 7000 feet of altitude, and we lost 30% of the nominal thrust here
I ended up fliying at half power most of the fligth and only whent full power for take off, verticals and a couple of high speed passes
Great plane overall and only modification was to the fuel tank, I moved the stoper to the center of the tank so the clunck can go all the way up and down
#82
My Feedback: (36)
Building another Cougar. I had the Skymaster X-treme F9F, now building the TopRC kit. The TopRC jet looks to be much better built, and the paint is MUCH better than the SM. Paint from the SM Cougar would come off in my hand when I picked it up...
Using MKS HV747 & HV1220 servos. Gear is painted, but work keeps getting in the way of my hobby. Planning to power with a JetCat P100RX. This one's gonna take a while. Most of these pics are from my SM Cougar, painted the bottom white, main gear doors added, Fei Bao F9F cockpit added.
Last edited by patniven; 06-28-2018 at 08:31 AM.
#83
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OK., I just got around to finishing mine up this week. Where did you guys figure your CG at. The online manual states 175mm back from intake lip . That is way off according to my calculations of the wing/fuse planform. I came in at 11 1/2"" - 285mm back. OR 4 "- 100mm in front of the rear spar / 1" - 25mm in front of the mains.
I will probably move it forward a bit more to be cautious for the first flight.
I will probably move it forward a bit more to be cautious for the first flight.
#85
OK., I just got around to finishing mine up this week. Where did you guys figure your CG at. The online manual states 175mm back from intake lip . That is way off according to my calculations of the wing/fuse planform. I came in at 11 1/2"" - 285mm back. OR 4 "- 100mm in front of the rear spar / 1" - 25mm in front of the mains.
I will probably move it forward a bit more to be cautious for the first flight.
I will probably move it forward a bit more to be cautious for the first flight.
The instruction book calls for 175mm back from the wing indentation (and handy-dandy panel line) - NOT the lip. Several other threads exist, and Bob Klenke had his at 185mm when we talked. I maidened at 185 and am moving it back (due to the amount of up elevator needed) as did he. I will try to pull the plane down tomorrow night (have a meeting until late tonight) and look at where you have it measured vs where I am now.
Greg
#87
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I initially flew my Cougar on a Jetcat P-60. It flew great and was very scale. However, the takeoff rolls were long and I was flying at 3/4 throttle or more most of the time. It was also obvious that flying off of grass with the P-60 wasn't going to be possible.
So I upgraded the Cougar to a Kingtech K85G2. I must admit that its much more fun now. Takeoffs happen in less than 200' (more like 100'), and its quite fast at full throttle. Its not exactly "scale-like" flying, but it does have more margin given the excess of power. Fuel consumption did not change significantly - it might e *sightly* better with the K85.
I'm also still moving my CG back a little at a time.
Bob
So I upgraded the Cougar to a Kingtech K85G2. I must admit that its much more fun now. Takeoffs happen in less than 200' (more like 100'), and its quite fast at full throttle. Its not exactly "scale-like" flying, but it does have more margin given the excess of power. Fuel consumption did not change significantly - it might e *sightly* better with the K85.
I'm also still moving my CG back a little at a time.
Bob
#88
Member
RE: Saddle fuel tanks.......has anyone installed saddle tanks (Sullivan 16oz) on this plane. I installed them on each side of the turbine therefore making them behind the CG. If you have, what affect did it have to the CG? and if so what did you do? I am using a P100rx and felt like I needed more capacity than the stock 68oz. I now have 96oz and should get 8-9 min flight. Concerned about the CG. Any help appreciated.
#90
My Feedback: (24)
Originally Posted by [email protected]
RE: Saddle fuel tanks.......has anyone installed saddle tanks (Sullivan 16oz) on this plane. I installed them on each side of the turbine therefore making them behind the CG. If you have, what affect did it have to the CG? and if so what did you do? I am using a P100rx and felt like I needed more capacity than the stock 68oz. I now have 96oz and should get 8-9 min flight. Concerned about the CG. Any help appreciated.
The P-100 is *a lot* of engine for the Cougar...
Bob
#91
Thread Starter
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I installed an 8oz tank in front of the main tank opposite the UAT. I find that after I fly for 5 minutes I'm ready to land and I always have 1/4 of the main tank left. I've never gotten into the fuel in the 8oz tank. The K-85 is a very fuel efficint engine - it burns the same amount of fuel (maybe less) than the P-60 it replaced.
The P-100 is *a lot* of engine for the Cougar...
Bob
The P-100 is *a lot* of engine for the Cougar...
Bob
#92
Member
The P100rx burns 12 oz per min. With a 68oz tank leaving 20% for emergency, that only gives me a 4.5 min flight. Your right, I have the 100 and do not want to have to spend more $ need the extra capacity....whata bout adding 1/2 the weight of the fuel in the saddle tanks to calc the CG?
#93
Originally Posted by [email protected]
RE: Saddle fuel tanks.......has anyone installed saddle tanks (Sullivan 16oz) on this plane. I installed them on each side of the turbine therefore making them behind the CG. If you have, what affect did it have to the CG? and if so what did you do? I am using a P100rx and felt like I needed more capacity than the stock 68oz. I now have 96oz and should get 8-9 min flight. Concerned about the CG. Any help appreciated.
Tanks are in series, draining the saddle tanks 1 and 2 then the main tank 3 and finally a 2 oz UAT. I fly for 8-9 minutes and land with a safe reserve in the main tank.
All this is at 7000 feet.
Hope this helps!
Greg
#94
Member
Jetflyr.................wow thanks your picture is exactly like the way I have my tanks set up as well. Is your tanks 16oz each? If so, should be the same amnt of weight.....Just to confirm, you balanced at 185mm WITHOUT FUEL. I have my tanks set up on a tee. The two saddle tanks should be used at same time before the main tank is used. Do you think this is ok? Just for info, do you remember how much weight you had to put in the nose for balance?
tks
tks
#95
Thread Starter
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Adding nose weight for half the weight of the fuel and tanks is splitting the baby, which is one approach. You'll be a bit tail heavy during the latter parts of the flight, and landing. The Cougar flies and lands well, so you may be just fine. I'd prefer not to add any extra weight at all. Is there room on top of the existing tank for a flat tank? For a plane this nice, a custom tank would worth the investment. Here's a pic of my jet with all kinds of stuff on top of the tank. There's room for a big flat tank there. I can put you in touch with a guy to build a custom tank that'll fit there like a glove if you are interested in this route. The advantage? No added nose weight and only 1 new tank instead of two. Notice the picture of the other guy above who did saddle tanks. He didn't use a tee, all three tanks are in series. This is an advantage over using a tee because unequal fuel flow won't leave one saddle tank with a little fuel in it.
#96
Originally Posted by [email protected]
Jetflyr.................wow thanks your picture is exactly like the way I have my tanks set up as well. Is your tanks 16oz each? If so, should be the same amnt of weight.....Just to confirm, you balanced at 185mm WITHOUT FUEL. I have my tanks set up on a tee. The two saddle tanks should be used at same time before the main tank is used. Do you think this is ok? Just for info, do you remember how much weight you had to put in the nose for balance?
tks
tks
Before I put the saddle tanks in I needed 4 -6 oz of weight in the nose, no change with the saddle tanks.
First flight was main tank only, then a single saddle, then both. The airplane didn't know the difference other than the extra weight for the first few minutes of the flight.
Do make sure you reinforce you main gear mounts before you have everything in the airplane .... they will need it!
Hope this helps!
Greg
Last edited by jetflyr; 11-04-2018 at 05:06 PM.
#97
I just saw your post on the other forum ..... it appears you have "regular" Sullivan 16 ounce tanks in there (rectangular).
I am using the Sullivan/Pylon 12 ounce SADDLE TANKS from the old DF days. Much thinner and curved, which fits the usage here, better.
Greg
I am using the Sullivan/Pylon 12 ounce SADDLE TANKS from the old DF days. Much thinner and curved, which fits the usage here, better.
Greg
#98
Join Date: Nov 2003
Location: Mexico CityD.F., MEXICO
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When I first read this thread, I was very concerned to put a Bee 80 in this airframe because I fly at 7000' altitude, we lost here near to 30% of the thrust (and the lift)
It turns out that the power was more than enough and it fly’s for 8 minutes with plenty fuel to land, and feels like a sport jet
Only modifications I made were to the fuel tank, I made a new stopper hole a little lower than the center, so the clunk could travel from the bottom of the tank to near the top
#99
Member
Well I have received a lot of suggestions....a couple have said they made no change to the CG with the additional tanks. So what I think I am going to do is balance the plane dry, then fuel it up and see if there is a significant difference. After seeing the results, ,if in fact is becomes noticeably tail heavy I may add a little more weight to the nose and try to make it 50/50 at takeoff and landing. I am at 5300 ft and want the extra thrust of the 100 but also do not want to have to spend more $....the throttle does not have to go all the way to the top
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