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Old Dec 15, 2004, 12:24 AM
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Madguns's Avatar
United States, FL, Navarre
Joined May 2004
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Aerographics Hawker Hunter

Hi everybody.
I need a little advice on a power set up for this smallish Hunter model I am building. It is normaly configured with a very small KP ducted fan for free flight. I feel that there is plenty of room for micro RC gear so I am building it that way. I have a EDF-55 that I could try to cram into the fuselage. I also have a Razor brushless and a P-10 controller. The pictures I took show the started fuselage and the EDF-55 on the plan for size and placment referance.
If I go with the fan, should I move it as far aft as possible? If I decide on a pusher set up, what then? So far the model is very light but the weight will go up when I sheet the fuselage with 1/32 contest balsa. I plan on covering it with very light iron on covering. I also plan on a elevon set up for control.
Any advise on which way to go as far as fan or pusher set up would be very helpfull. Thanks.
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Old Dec 19, 2004, 05:44 PM
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Well I decided to go with the ducted fan
If it flies well it will be from sheer luck. This is the first electric ducted fan model I have attempted. I mounted Razor Micro V.2 on the EDF-55 and then made a hollow balsa tail cone to smooth things out in back. I also drilled in some heat vents into the tail cone. Still have to finish sheeting the fusalage and hog out the intake and exaust. Any thoughts?
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Old Dec 19, 2004, 06:14 PM
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Wareham, Dorset, UK
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Hi Madguns
have you thought about the inlet ducting?
What about that discontinuity behind the motor tube?

Klaus
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Old Dec 19, 2004, 06:56 PM
Watts the Point
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KY,USA
Joined Jul 2004
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Can the tailpiece it's blocking too much of the duct behind the fan unit.
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Old Dec 20, 2004, 09:48 AM
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I had to cut off the inlet ring just to get this fan to fit inside the fuselage.
The ducting will be through the scale intake. They seem big enough. I think the cone may help the performance a little, if not I will take it off or make a slender one. The intake and exaust will be the airplanes 1/32 skin. I will grind down the bulkheads after the plane is fully sheeted. Wont be smooth as fiberglass but the airflow should be pretty unobstructed. Raw power may be enough to motivate this thing, if it doesnt fly... oh well, chalk it up to the learning experiance I guess.
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Old Dec 20, 2004, 10:07 AM
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Fan placement looks to be just behind the trailing edge of the wing...looks like a good spot.

The tailcone is ok but yours is too fat, just make it a triangle shape no larger than the motor. It will however reduce the amount of the motor casing that is exposed to the air and thus could reduce cooling. Taking it off completely wont make a huge difference in thrust, but will help ensure motor life, depending on how hard you plan on pushing the motor.

Not much room for exhaust ducting in there, but you don't want to constrict the exhaust too much. Grinding the bulkheads down will give you more room, but you need to put in some sort of exhaust liner to keep the walls smooth. Computer printer photo paper would work, or even some thicker printer type paper. If you have the remains of bulkheads and stringers inside the exhaust all the protrusions will kill your thrust level.

How big are the inlets in square inches or millimeters? The thinking goes that the smallest inlets you can get away with are about 90% of the FSA (Fan Swept Area). The FSA is calculated by finding the area across the entire fan diameter and subtracting the area that is covered by the motor housing/spinner/hub. When you have that number, see how close the inlet area is. If you end up with only 60 percent of the swept area for your inlets, the fan won't get enough air. You can use cheater holes or enlarge the inlets. The bigger the inlets the better, with larger ones you get better low end thrust and climb rate. You can get away with smaller inlets if you bungee launch, the bungee will accelerate the plane quickly so that the fan gets "on step". You can hand launch as well, but it will take longer to get on step and sometimes you can't get on step if you don't have enough power to get going fast enough. With brushless and lipos you should do ok.
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Old Dec 21, 2004, 02:51 AM
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United States, FL, Navarre
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Thanks for the Info!
I will try and get some intake numbers and see what were looking like. I have a feeling that a cheater hole will be needed.
I have been spending a great deal of time building the horizontal stabilizor. The kits design is not good enough for R/c aplications. Very week.
Thanks for the tip on the exaust ducting. I will try to get it as big and as smooth as possible.
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Old Dec 28, 2004, 03:00 PM
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Thanks ED!

Well thanks to Mr. Waldrep I saw the light and decided to build an intake for this little hunter out of printer paper. I must say that while its not the easyest to work with, it did impress me. I made it go around a few curves I didnt think possible. I think that this plane will fly
I installed the intake after hogging out the balsa bulkheads. They are as wide as I could get them. The paper really smoothed out the airflow pathway to the Fan. Once I got it all sealed up to the fan I ran up the RAZOR and was shocked when my hand was sucked into ONE of the intakes. I am still not rulling out a cheater hole. I will have to see how it flys and if the plane is able to "Get on Step". Thanks for the advice Ed
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Old Jan 04, 2005, 04:39 PM
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United States, FL, Navarre
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Hawker Hunter Progress

After lots of surgury to make this plane accomodate the EDF55, covering has been started. I am using BALSALOC and Coverites Coverlite. I am not used to useing this method to cover models but it seams too work pretty well if you follow the instructions to the tee. The fan has power but I dont think it will be a good flyer as a ducted fan model. I think it would be better suited to pusher power. If flight is impossible or pathetic I will change it over to a pusher set up. Anywho here are some update pics.
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Old Jan 04, 2005, 05:09 PM
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Wareham, Dorset, UK
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Hi Madguns

the Hunter is a mighty nice aeroplane with a generous wing area and big inlets for the air hungry Avon/Saphire. It should fly with fan power if you dont build too heavy.
Looks very good so far; perhaps you should try to overskin the port (left) outside of the air inlet again (use the balsa with the grain running lenghtwise - it's easier) before covering with film. Would give smoother and cleaner defined lines.

Have fun with fans

Klaus
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Last edited by winmodels; Jan 04, 2005 at 05:11 PM.
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Old Jan 04, 2005, 05:19 PM
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United States, FL, Navarre
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Hi Klaus

I must say that since I have been in the UK I have come to realise just how pretty some of the cold war RAF and RN aircraft are. They all seem to have the same basic air intake design too. I have taken great pains to keep this model light, but you know how that goes. From the fan back the internal structure has been wittled down to the sheeting. Its just 1/32 sheet holding hands back there It is fairly strong though. I guess we will see.

John
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Old Aug 05, 2008, 03:40 PM
Trying To Takeoff
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Novosibirsk, Siberia
Joined Dec 2006
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Have you finished it?
Thank you,
Kostya
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Old Sep 04, 2008, 06:23 AM
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Hi
i built one of these last year for free flight using a kp fan and a 4 cell nim-h
its realy is a great - im interested to see how modification to rc turns out- good luck!
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Old Sep 04, 2008, 08:13 AM
Trying To Takeoff
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Novosibirsk, Siberia
Joined Dec 2006
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Quote:
Originally Posted by tailspin450
Hi
i built one of these last year for free flight using a kp fan and a 4 cell nim-h
its realy is a great - im interested to see how modification to rc turns out- good luck!
cool! post pictures please! Mine from is in delivery right now.

Kostya
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Old Jan 21, 2014, 07:57 AM
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Farnham Common, UK
Joined Oct 2009
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Aerographics Hawker Hunter

Hi Madguns.

I realise it's more than 5 year since the last post on this thread but I wondered whether you ever completed and flew your Hunter? If, so any information on how you got along after your last post would be very interesting .

My build is underway - build log on the micro edf forum.

Jeremy BB
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