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Old Aug 21, 2012, 08:58 AM
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United Kingdom, Northern Ireland, Belfast
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I started this model ages ago Joe and I can't remember why I put it aside. Anyhow, Watching yours had made me get back at it. I will post some pics soon. I was wondering if you could help with a couple of measurements? I need the size of one of your intakes please.

I can't remember if I scaled mine up or not.

BillO... That is a lot of work to cut down blue foam board. But neat job you've made of it. I'm watching intently.
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Old Aug 21, 2012, 02:21 PM
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United States, WA, Vancouver
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@Shane Sunday,
kinda confused at your questions....if you started this model "ages" ago you must be building a different version by somebody else....I just posted my Phantom plans last month...the size of the intake...? ..its on the plans...


Joe
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Old Aug 21, 2012, 06:21 PM
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Joe you are correct. I am mistaken. I started the pusher F4 from Parkjets ages ago. My mistake.
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Old Aug 22, 2012, 02:57 AM
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no problem I kinda thought thats what might have happened.

Joe
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Old Aug 25, 2012, 06:11 PM
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Well either way Joe your F4 got me back into building this one. Since I saw yours fly so well I decided to build mine as an EDF using a unit I had picked up from ages ago. It's actually 80mm and I never ever found out the kv rating on the motor. I picked it up back when I first started and knew nothing but wanted everything. Anyhow it has some thrust on just a 3s set up so we shall see. Since I found your build I've built this exhaust. I figured I'd give it a go for the up coming 60" wingspan.

Pink Expanded foam cut using hotwire table then glued together. Lots of sanding a mud to get her to the required shape. I then covered it in white glue and newsprint. the idea was to wax the print then vasoline to help release the plug. In the end all the newsprint stayed with the exhaust. Still it's nice inside and I feel it adds some strength. Also I was running low on glass cloth so i grabbed the nearest thing... Bounty paper towel re enforced at the openings with fibre glass tissue. the whole thing weighs 3.5 oz and is very strong. with the fan unit and motor it all weighs 9.5 oz.


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Old Aug 26, 2012, 09:59 AM
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Im not knocking you in anyway so dont take this wrong.

hefty hefty hefty.......

The use of bounty paper towels, i just had to repeat the TV commercial.
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Old Aug 29, 2012, 08:47 PM
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hey Shane,
I think you might want a sharper splitter on your exhaust, I am by no means an expert but it would seem the "rounded" splitter might be detrimental to your thrust, your eflux would be slamming into a wall, if the splitter is sharp it dosent hit anything to slow it down., your Phantom looks cool so far.

Joe
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Old Aug 31, 2012, 03:01 PM
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Here's my pile of parts, pretty much everything except for the doublers. Weight is 174 grams or just over 6 oz. This foam seems to be in the ballpark weight-wise anyway.

I'm going to glass it to give it a little more strength. I have a huge roll of 1.6 oz so that's what I'm going to use. I know most guys use 3/4 oz but that just seems so flimsy!
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Old Aug 31, 2012, 06:20 PM
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Crystal River Fl.
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Hi Bill, nice pile-o-parts . Your 1.5oz glass is really pretty heavy for this bird, I like others use the 3/4oz, plenty strong and even that can be pretty heavy sometimes.. If I was going to use the heavier glass, I'd use very little and only on the bottom to help with landing rash.. Good luck, w
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Old Aug 31, 2012, 10:19 PM
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I'am with Walt on that one, (personally I wouldnt use any glass) unless you are installing a fan that has more get up and go than the one I used the lighter you keep it the better it will fly, it may seem "flimsy" right now but after all the main structural parts are assembled it is quite strong and stiff, just my 2cents.

Joe
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Old Sep 01, 2012, 12:36 AM
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Thanks Walt and Joe, I will be using a different fan with a little more juice. But I was wondering Joe, about the launch in the video. If the jet AUW is 28 oz and the fan puts out about 40 oz shouldn't that thing just climb straight up right out of your hand? Maybe you weren't using full throttle?
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Old Sep 01, 2012, 01:55 AM
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by all means if you are going more power and bigger battery payload then adding a little beef to the airframe is needed, didnt know if you were using the Detrum combo or not.
I usually launch at just over half throttle, most of the flight you see on the video is half to three quarter throttle, I throttle up after launching to get it up and on step then back off when shes at a good "cruising" speed, I use an 1800mah battery in the Phantom because it was the lightest weight battery that could get the job done, it does full throttle just fine, but I fly at a schoolyard so full throttle can cover a large distance awefull quick, and the flight time would be less, my design emphasis is to lean more to the park jet side of things more than the raw power and speed side Lt599 has run these units on 5s with 975 watts and 56amp draw, I havent tried that...yet , but the option is there.

Joe
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Old Sep 01, 2012, 12:48 PM
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I guess is better divulge my whole plan then. You have a nice formula for the light park jet, but I would be thrown out of any park around here with an RC plane! I'll be flying at a regular club with an Astroturf landing strip. A belly lander will need a bit more protection for that.

One of the things that has got me interested in jets is the possibility of having a really cool sound. I ordered one of the Extreme RC alloy shroud setups with the CS 10 blade fan. On 4s it makes about 52 oz of thrust on 900 watts. I'm also going to add ailerons and ducting. All of these things add weight. I'm hoping to bring it in around 36 oz AUW with installed thrust of 42 oz. This is still a pretty light wing loading, under 20 oz/sq ft, so I still plan to hand launch it. Wish me luck!
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Old Sep 01, 2012, 02:01 PM
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I saw the video of that unit in an F-16, the sound was awesome! so good luck on the maiden and get a video if you can, would love to hear that sound come out of the Phantom!

Joe
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Old Sep 01, 2012, 06:42 PM
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Quote:
Originally Posted by BillO View Post
I guess is better divulge my whole plan then. You have a nice formula for the light park jet, but I would be thrown out of any park around here with an RC plane! I'll be flying at a regular club with an Astroturf landing strip. A belly lander will need a bit more protection for that.

One of the things that has got me interested in jets is the possibility of having a really cool sound. I ordered one of the Extreme RC alloy shroud setups with the CS 10 blade fan. On 4s it makes about 52 oz of thrust on 900 watts. I'm also going to add ailerons and ducting. All of these things add weight. I'm hoping to bring it in around 36 oz AUW with installed thrust of 42 oz. This is still a pretty light wing loading, under 20 oz/sq ft, so I still plan to hand launch it. Wish me luck!
A couple of things here I want to comment on, and bear in mind that this is just advice offered trying to help... I'm no sure how many jets or belly landers you have, but I have several jets and none of my current planes nave any landing gear at all, they are all belly landers. I fly at two fields that both have a material landing strip it is smooth so I don't know how that compares with your astro turf stuff, I land in the grass and also on the material, about 50% of my planes have no glass, and some have just foam and no other protection. Yes you will get minimal rash on bare foam, but not bad, on ones that do have glass, typically you don't fet rash, but it is possible, those that have another type of finish like ply/talc you get minimal to no rash, so belly landing does not necessarily need or warrant glass, and especially heavier glass for good results. Secondly,, hand launching a 3lb+ plane is very difficult if not close to impossible, I'm sure it can be done, but you will find that those flying EDF's of this size and smaller, and larger are using either gear(which adds more weight and drag) or using a bungee launcher. Bill even if the plane is planed to have more thrust than weight you do NOT have any control until the plane is up on step and that takes some distance and speed.. You may want to talk to some other guys that are experienced with EDF's and the larger size that you ae planning to get some more knowledge, before spending your money and doing a lot of work building a nice plane to have it destroyed attempting to hand launch it... Good luck w
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