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Old Nov 20, 2011, 06:50 PM
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Was this with CG as per instructions ?
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Old Nov 20, 2011, 06:52 PM
It should fly at least once
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It looked like it just stopped in mid air...., certainly looked tail heavy.
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Old Nov 20, 2011, 06:53 PM
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Very
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Old Nov 20, 2011, 06:58 PM
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Quote:
Originally Posted by Gaz-b View Post
Was this with CG as per instructions ?
Yep pilot said it was. tail heavy it appeared, even weight added to tail to balance.

Some flap used for take off

I think underpowered on stock, not 1-1 power, 6s.

Crying out for a turbine
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Old Nov 20, 2011, 06:59 PM
It should fly at least once
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Gaz....did it look like to you that as soon as it came of the bungee it had no power to push on forward and then tip stalled, I thought at first it had caught the bungee line but then noticed the dolly. It just came to a halt.

What power system was it using, sounded like the jet 90??????
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Old Nov 20, 2011, 07:04 PM
It should fly at least once
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mk1spitfire what power system were you using???? also what bungee pull did it have (pounds or Kgs) lot of drag from the grass so low air speed all combined from what I saw.............
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Old Nov 20, 2011, 07:08 PM
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Originally Posted by clive45 View Post
mk1spitfire what power system were you using???? also what bungee pull did it have (pounds or Kgs) lot of drag from the grass so low air speed all combined from what I saw.............
I was video, not pilot. I believe stock power system, assuming fan/motor came with HK kit.

6s.

Jepe launch bungee system.

Pretty plane, but underpowered

Bungee appeared to overcome drag of grass, just not enough oomfff from edf after.

Shallower pitch MIGHT have helped but it was all touch and go. Slight headwind too.
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Old Nov 20, 2011, 07:13 PM
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hey Spitfire-
where did you have the CG set? I have the same plane and would like to learn from your experience- sorry that it happened to you- lovely plane.
How many watts does your power system produce? I am planning to use a 3000 watt setup, yielding a bit more than 400 watts per pound, if I can keep the weight at 7 pounds, that is.To my eye, it did appear tailheavy and or underpowered. I have read that the CG recommendation in the "manual" is incorrect- too far back.
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Old Nov 20, 2011, 07:20 PM
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Quote:
Originally Posted by mk1spitfire View Post
Yep pilot said it was. tail heavy it appeared, even weight added to tail to balance.

Some flap used for take off

I think underpowered on stock, not 1-1 power, 6s.

Crying out for a turbine
As discussed before on this airframe the instructions are 20 odd mm out from what I have read cg works from 95 to 110 mm 110 seems to be the norm.it loked to me like as soon as it was clear of the ground it dropped its ass.
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Old Nov 20, 2011, 07:24 PM
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Gaz, i agree. am planning right now to use 105 mm measured back from the wing/fuse junction.
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Old Nov 20, 2011, 07:26 PM
It should fly at least once
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As far as I know it does not come with fan or anything. The fan sounded quiet like a jet 90 or CS 12 blade. I would be interested to know just exactly what he was running as well as to the battery's, a wattage figure would be good.
Very sorry to see such a nice plane hit the deck but it seemed to survive quite well.
I wonder if HK will sell spare parts or how long it is before they come back into stock, I assume they will come back into stock soon. Might be worth getting an extra one for spares.
If its like the viper 90 they say the C of G is about 30 mm too far back, the more I look at the vid my opinion is lack of power and tip stall. C of G may have been contributing to the crash but lack of air flow and no control does it every time
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Old Nov 20, 2011, 07:34 PM
"Take Off" eh!
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Sorry for your friends loss mk1spitfire... But that was a well made video!

For sure that was the stock CG of 135mm. 105mm seems to be the sweet spot from what Im reading.
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Old Nov 20, 2011, 09:48 PM
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Any crash is unfortunate. However, it can be rewarding for lessons learned.

Bungee launching is in my plan for a CMPro T-45 (Nitroplanes). What I have picked up from RCGroup Forums: The bungee shall be pull capable of five times the aircraft weight; bungee attachment at 33% forward of the CofG; Power shall be applied only after release and the aircraft is flying level.

If the aircraft is balance, it should fly straight and level (?) with all control surfaces in neutral when released into a headwind. Perhaps, if the aircraft is allowed to glide, CofG may be evaluated.

Just my $.02.
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Old Nov 20, 2011, 10:04 PM
It should fly at least once
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Are we to assume that the crashed Hawk did not have sufficient pull as it seemed to stop on launch even with the motor running. I did also detect a noise as it left the dolly, could it be the aircraft was caught on the dolly thereby loosing significant launch speed
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Old Nov 20, 2011, 10:10 PM
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it looked pretty slow to me when it launced in to the air.
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