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Comp ARF BAE Hawk build thread

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Old 04-02-2019, 05:03 PM
  #2276  
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Originally Posted by jetmodeller View Post
Hi all just bought a second hand C a r f Hawk just two hours flight time and very well built, jet munt 140 and flys great.
it does not have the fuz strakes and if some body would be good enough to let me know the measurements I would be very grateful , width front and back and length would be good.thanks

has taken me a week to read this thread from start to Finnish!, but well worth it
Is this what you need?
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Old 04-02-2019, 11:29 PM
  #2277  
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Hi yes that’s great many thanks keith
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Old 05-11-2019, 07:57 PM
  #2278  
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Originally Posted by rhklenke View Post
My son Louie's CARF Hawk is plenty fast on an "old, old" Cheetah! I can only imagine how fast it would be on a 170 Cheetah!

Dave Wilshire has pointed out several times that aileron crow is not necessary to land a CARF Hawk, but we can tell you from a *lot* of experience on hard-surface runways in various wind conditions, that aileron crow with full-flaps makes landing much more of a non-event and much less anxiety producing...

Nice plane Rich!

Bob
Hey Bob, how much crow are you guys running on the ailerons? Im hopping to dust off my hawk this year and get it flying again after sitting for a few years now. I have to set up the radio again since i lost some settings on the power-box when it was sent in for a screen replacement.
Thanks!

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Old 05-11-2019, 09:40 PM
  #2279  
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Very little, I will have to double check mine but if I recall it’s around 1/4” of crow.

Last edited by Dieselman1220; 05-12-2019 at 05:50 AM.
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Old 05-12-2019, 01:23 AM
  #2280  
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Default Leg doors

Hi is any body making the u/c leg doors, the ones that fit to the legs?
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Old 05-12-2019, 05:38 AM
  #2281  
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I use 3/8” of crow and I believe that’s what Bob Klenke uses as well. Only with full landing flaps, none at half or takeoff setting. It makes the airplane settle instead of floating and then dropping all at once.
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Old 05-13-2019, 11:02 AM
  #2282  
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Thanks guys!
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Old 05-13-2019, 01:19 PM
  #2283  
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Just reducing the overall lift the wing can develop. 3/8" is a load 1/8" may help if the aileron neutral is not set correctly. I'm not aware of a single CARF hawk flying in the UK with any CROW...
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Old 05-13-2019, 04:27 PM
  #2284  
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Hey Dave, one issue i remember on the hawk i could not get it to stop doing is when i was short final and brought the throttle back to idle it would wing rock all the time. I'm hopping the crow would help with that. I even added a Igyro 3e to see if that would help but i never got around to setting the gyro up. only have one or two flights with the gyro never flew the hawk again.
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Old 05-13-2019, 09:04 PM
  #2285  
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Never experienced that, the main issue I think that is driving this is the flaps don’t go fully up because of how they go under the fuselage fairing. Some work on the fairing and the flaps nearly go up enough to meet the wing profile. If you set the ailerons level with the flap it has wash-in with drooped ailerons. I set the ailerons by the tip mould seam, for some owners I might even set the ailerons a 1/8” high to add a little more washout. It lands solid like this

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Old 05-14-2019, 10:20 AM
  #2286  
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Fully agree to Dave. I fly this Hawk since 5 years without any crow needed whatsoever. It lands even more beautifully than the big one (1:3,5)
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Old 05-14-2019, 03:32 PM
  #2287  
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Well , it works exceptionally well for me.

If you catch a gust that causes you to balloon a couple of feet above the runway on landing approach and your speed is low and your engine is not spooled you will cartwheel. It does happen. Ask me how I know 😬

If it happens, maybe one of these guys who say it’s not needed will repair your airplane gratis. There is No downside to having some crow in the landing flap position. A little extra drag is helpful on landing and it helps the wing to stall at the root before the tips.

I don’t use it in the mid “takeoff “ position as I don’t want any extra drag or lift killing aspects on takeoff.

They screwed up the wing saddle molding and when the flaps are “ up “ they are really not completely up. So if you match the ailerons to the flaps the ailerons are actually drooped. This accentuates the roll off of the airplane at low airspeed. In reality, crow is just correcting the MFG error. Personally ,I don’t like the looks of aileron reflex with the flaps up ,so I only deploy it with full flaps. I also don’t need it at cruise.
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Old 05-15-2019, 06:21 PM
  #2288  
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Totally agree with you Bob, as Dave stated don't line up the ailerons with the flaps, follow the mold line on the wing and that will naturally give the
ailerons a few mms of reflex. This got me thinking, while I love crow, and use it on my hawk. In over 400 flights on my hawk Ive never done any stall testing with it.
Conditions were nearly ideal today with almost zero wind so I took her out and put 5 flights on it. I was really surprised with what I found. In the clean configuration
this jet will stall like a 172. I had full up elevator and she absolutely would NOT drop a wing just sit there and porpoise up and down the whole length of the field.
It was very impressive I wish someone would have recorded it. In landing configuration gear up (with crow) she pretty much did the same but was sinking a bit more, but still
remained completely wings level.
It gave me a lot more confidence in a jet that I already have a tremendous amount of confidence in. I will have to record my elevator throw and CG to share, as that
could obviously change someones results. For what its worth mine is powered with a cheetah 140 and weighs in at 28 pounds dry.
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Old 05-16-2019, 05:19 PM
  #2289  
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Well, I have a lot of flights on my old Hawk and never used Crow, I did not line up the ailerons with the flaps, I did it like Dave told us to. But I am surprised you could not get a wing to drop when intentionally stalling her, I occasionally pull to much elevator when horsing her around, usually after flying my F-16 or something and mine definitely wants to snap at any speed with enough AOA.
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Old 05-16-2019, 09:19 PM
  #2290  
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This is what some pilots don’t seem to understand. You can get an airframe that seems completely stable to snap if you pitch fast enough. The sudden change in AOA can cause the airflow to break away and the wing stalls. Do it slowly and many wing sections will fly at huge angles of attack and although the lift is reduced there is not a violent stall.
This goes for pilots who suffered snaps on the UF, Xcalibur and other well known airframes, if you grab at something it will break away. Like driving your car fast around corners, steer smoothly and it will grip to incredible levels, snatch at the steering and you will get understeer and the thing will not turn.
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Old 05-16-2019, 09:48 PM
  #2291  
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Point well taken. But the Hawk is capable of wicked snaps and done on purpose it’s a nice feature. This Hawk, even being a sport Hawk , should still be flown with care. I would not recommend large control surface deflections or excessive expo, or “horsing it around” the pattern.
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Old 05-16-2019, 09:49 PM
  #2292  
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I agree with what DW says completely.
ill add all my stall testing was straight and level.
Your CG and elevator throw will also affect the behavior.
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Old 05-17-2019, 05:44 AM
  #2293  
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Originally Posted by Dieselman1220 View Post
Totally agree with you Bob, as Dave stated don't line up the ailerons with the flaps, follow the mold line on the wing and that will naturally give the
ailerons a few mms of reflex. This got me thinking, while I love crow, and use it on my hawk. In over 400 flights on my hawk Ive never done any stall testing with it.
Conditions were nearly ideal today with almost zero wind so I took her out and put 5 flights on it. I was really surprised with what I found. In the clean configuration
this jet will stall like a 172. I had full up elevator and she absolutely would NOT drop a wing just sit there and porpoise up and down the whole length of the field.
It was very impressive I wish someone would have recorded it. In landing configuration gear up (with crow) she pretty much did the same but was sinking a bit more, but still
remained completely wings level.
It gave me a lot more confidence in a jet that I already have a tremendous amount of confidence in. I will have to record my elevator throw and CG to share, as that
could obviously change someones results. For what its worth mine is powered with a cheetah 140 and weighs in at 28 pounds dry.
Sounds very similar to my setup, I will try some stalls with mine this summer as well. I’d like to hear about your cg and throws.

I use crow crow in mine, and I agree it’s not “needed” but we do a lot of things in our hobby that we don’t “need”. For me I find it just adds a little more stability and helps to slow it down. So I’ll keep using it, I like the way it feels.
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