causeitflies

causeitflies

i3dm

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i believe the motor gear boxes were the limiting factor

ECalderon

Hi.

I am in the final stages of my build and have a question.
I know the wing tubes are clamped to the fuselage, but what prevents the wing from sliding off the tubes since nothing hold the wing to the fuslege? Only way I see is to glue the tubes to the wings, screw the wing to the fuselage at the root, or insert a screw in the bottom of the wing that goes through the wingtube.
How have you guys done it?
Thanks in advance for your answer.

Regards
Eduardo

vquick

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yes you have to glue both tubes to the wing just mark the tube and ruft sand that area and glue with 30 minutes epoxy

i3dm

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Yes the tubes are designed to be glued into the wings.

paultzr

I have just taken delivery of my Top RC Hunter the main gear doors are missing from the fuselage and there is no instruction manual with a check list of what should be provided, I see in this thread you all appear to have the small inner doors hinged from the fuselage, I'm trying to find out if they are missing from my delivery.
Regards
Paul

paultzr

Please ignore my last post as I have now fully unpacked my Hunter and found the doors and down loaded the manual.

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I downloaded the manual. The front cover says the CG is 290mm from the leading edge at the wing root. Yet inside the manual, it says 240mm from the same place. That's a 50mm difference, almost 2 inches. I read thru this thread and didn't find anyone dealing with this issue. Can you guys who have flow this jet tell us your CG location? Thanks!

vquick

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Yes the cg in this plane is 290 to 300 mm

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Ha, that'll save some weight. What made you go with the 290 vs the 240 inside the manual?

Dave Wilshere

Be careful, there is a huge balance shift on this model. I test flew one Saturday for a friend, it was hugely nose heavy because it was balanced with landing fuel only. I suggest balancing with half a tank.

Dave.

causeitflies

Balance EMPTY (full air trap) at 290mm and it will be a good place to start.
P.S. Have never flown without the tanks.

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So was it nose heavy right upon takeoff?

Dave Wilshere

Yes, it was very nose heavy on take off. Will find out which balance point he used. I had him take a huge lump of lead from the nose after the test flight and I think maybe more will come out.
I had him take the tanks off just before we flew as the factory mounting points were not parallel to each other or fuselage! He’s adjusted them now and we will try again this weekend.
Also the wing panels worked out on one side taxiing on our grass strip. The soft alloy tubes need a block inside I think.

Dave

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You Brits are usually more articulate than we in the colonies, so I'm having trouble visualizing the meaning of the bold. Like, where did the jet get fuel if you took the tanks off before you flew? And, are the soft alloy tubes the SPARS? If so, and they're soft, I'd say taxiing is the least of the worries. Maybe a little edification would help. Thanks!

ECalderon

Hi,
I believe Dave is refering to the wing tanks. With respect to the aluminum tubes, the two thicker ones are supposed to be glued to the wing, and when attached to the fuselage they are clamped by a clamp installed in the factory. For this a hole must be drilled in the bottom of the fuselage to access the screw to tighten the clamp.

Regards
Eduardo

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Doh! I never thought about the WING tanks. I bet removing them even made it more nose heavy. I actually have two Hawker Hunters, one is a smaller Century Jets version, and the other is the TopRC, which I have not started yet. I compared the recommended CG from both companies, and once scaled they are almost both the same. The Century Jets is the one I'm balancing, otherwise it's done. It came with no fuel tank, so I had to make my own. Anticipating the weight shift, I designed an unusual long tank to minimize it. The fat part in front is between the two intakes, and the long tubular section extends aft of the intake bifurcation. So, I used Solidworks to design the plug and also to calculate the CG of the tank alone. Using that location, I placed a weight on the plane during balancing to simulate 1/2 tank load and then proceeded to balance the plane. This resulted in almost 10oz less nose weight than balancing empty. Here's a couple pics of the whole process.

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And here it is being balanced. I don't have the weight simulating the tank 1/2-full weight in this picture, but it's a drill chuck sitting between the aft portion of the two sabrinas. It was a coincidence the chuck was the right weight. I got lucky.

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I finally got going building my actual top RC Hawker Hunter. The first thing I noticed that needed changing was the flap hinges. I didn’t like the way they stuck down from the lower wing surface so I did this modification to make them flush. So far they seem strong and work fine and they look much more Scale. Also there are fewer protrusions to get caught and broken during handling.

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I hate to keep beating a dead horse, but I'm now balancing my TopRC Hawker Hunter and I want to address the CG location again. In my original post, I noted the manual says 2 different measurements "from the same location". Well, I was wrong, it gives 2 different numbers from TWO different locations. The inside of the manual gives 240mm from the outer tip of the air inlet. The cover of the manual states 290mm from the tip of the wing root joint. Note in my scaled photo that there is close to a 1 inch difference in those two reference locations. So where is your reference location for the 290-300mm measurement? Thanks for the help!

The .98" is the difference between the two CG starting points. I didn't show the 240mm because almost everyone agrees that is not the right number.

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This thing barely fits in my build space.

This is my home-made UAT. Just bought a lexan tube and made end caps. Total cost $20.

ECalderon

Hi, f

From what I've researched in several sources online, the perfect CG for this plane from people that have flown it, is located right at the dot (.) after the "www" that is incribed in the turbine mounting plate. There is where I have my CG and I pretend to maiden it this weekend.

Regards
Eduardo

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Thanks for the info. I plotted your estimate of CG onto my CAD drawing. That places it around 265mm behind the reference location as stated INSIDE the manual. The most important parameter is; is that 265mm with tanks full, half, or dry? Also, bear in mind that whoever is laser etching the lettering into the engine mounting rails is not necessarily going to locate the lettering the same place every time.

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