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Old Dec 28, 2006, 08:21 PM
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Joined Jun 2006
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How fast HET F-18 need to go to take off on Wheels?

I have a Het F-18 and try to take off from atrol turf. I have small wheels and I gues the F-18 max around 20mph on the astrol turf. It didn't lift. How fast does it need to go on wheels before it take off? The plane have about 750 gram of thrust and weight 34 oz.

I have taken the the ESC out of the duct and seem to get more thrust. Will try again tomorrow.
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Old Dec 28, 2006, 08:58 PM
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Ed Waldrep's Avatar
Las Vegas, NV
Joined Dec 1996
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No idea on the exact speed needed but there are things you can do to make the takeoff happen at a lower speed.

First, lengthen the nosegear strut so that you have a higher angle of attack for the wing. You want at least 0 degrees of incidence for the bottom of the wing, but two or three degrees is even better. If you can't lengthen the nosewheel strut, you might be able to lower your rear/ maingear somehow. Spread out the wire struts or make shorter ones (don't know how yours is setup).

Second, if the above doesn't work, try a larger nosewheel, or smaller mains if you can, or both.

The high thrustline of the tail is wanting to push the nose into the ground, and you have to overcome that force by the tailerons pushing downward, the more speed you have, the more downforce they can provide, but obviously you're not getting enough. Lifting the nose by lengthening the gear is like getting that downforce for free. Getting the wing at a few more degrees of incidence will give more lift and make takeoff possible hopefully, it sounds like you have enough thrust.
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Old Dec 28, 2006, 09:44 PM
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Thanks for the tips. Today, the wing probably have 0 degree. I lowered the 2 back wheel strut and the wing now have about 5 degree of incidence. Cross my finger that this will work. Beause I love to take off on wheels and hate to put 2 inche wheels on the F-18.
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Old Jan 03, 2007, 01:32 PM
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Ed Waldrep,

Thanks for the tips again. After the modification with bigger wheels, and longer nose struct, the first attempt was no good because people were on the Astrol turf, so I tried to take off on grass, but unfortunately the wheel hitted the bump and flipped to the left and snapped off the left wing. Was kind of upset. Then I glued the wing on and tried out this morning and it just took off about 90 feets later. It flew very nice, very perdictible and stable.

My power setup was a little on the slow side, 40, 50mph. Don't know if the wheels slowed it down, or I didn't charged the battery fully. I will go try it out tomorrow again and see how it fly.
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Old Jan 03, 2007, 03:09 PM
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dusmmdb34's Avatar
Alexandria LA
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What power setup are you running?
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Old Jan 03, 2007, 04:27 PM
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I am running an Align 3550 KV motor, known for Electric Heli motor run on 3s1p 2200mah. I actually have the thrust exit aimed at the scale and it show around 800 gram, 28.5 oz. of thrust and my F-18 is 1030 grams.
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Old Jan 04, 2007, 02:54 AM
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kriptonic's Avatar
Los Angeles
Joined Aug 2004
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I think that motor your using is too small for EDF use for the HET F-18, you might want to try a mega/hacker inrunner. I have align motor in one of my helicoptors, but i sure wouldn't use it in an EDF setup since it won't give you the power you need. I'm running a mega 16/15/3 on 3s2p 2000 lipos (4000mah total) on my T-33,,,yes i got a new T-33... and i'm going to fit it with retracts .

Gene
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