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Old Jan 25, 2004, 08:32 PM
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Chris Golds Sea Hawk?

Did he design one of these? anybody know anything about it?
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Old Jan 25, 2004, 09:54 PM
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British naval fighter right? Yes he did. It is a plan available from the English electric flight mag - Traplet. It's designed for a midi fan but it was hugely heavy and big - probably you could fit a 730 in there! It was 7+ pounds on 14 cells, it'll work but plan on a much larger load of cells to get any kind of performance out of it
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Old Jan 25, 2004, 10:03 PM
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Size?
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Old Jan 25, 2004, 10:42 PM
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I managed to find the articles - May and June of 2002. I had my planes confused, the 7+ pound monster was a Swift. This one is Bungee launched with no gear. No specs for span or anything but he says RTF weight is 98.5 ounces, wing loading 20.5 and watts per pound 110 so you can work out the area.

Same comments as for the Swift, plan on adding 50 - 100% to the cell count and you'll have a good flyer.
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Old Jan 25, 2004, 10:44 PM
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Curtis,

Think it was about 60-61'' or so.

Thanks,
Mark
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Old Jan 25, 2004, 11:01 PM
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Old Jan 25, 2004, 11:35 PM
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That nose gear was a display only piece. Lotsa plane there!
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Old Jan 26, 2004, 12:04 AM
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Seahawk plan

https://www.traplet.com/pages/nonmag...d=3577&-search


Thanks,
Mark
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Old Jan 26, 2004, 02:27 AM
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As Chris T said, oversize and underpowered with the specified setup. Without retracts, it bungeed off and cruised around looking pretty, but that was it. It wasn't an aerobatic jet.

After this initial "success" Chris G fitted the retracts and tailhook, and made two flights attempted. On both, it only just managed to leave the ground, eventually crashing during the first left turn following retracting the gear due to insufficient flying speed to hold height in the turn. The first time it was repairable; the second time it turned left and smashed into the chainlink fence which bounds our flying site, and that was the end.

The intakes and exhausts were too big in area for a 90mm fan so with drag from the oversize inlet, and slow efflux velocity from the oversize tailpipe area, it wasn't ever going to be a quick model.

Lovely looking model, but needs much more power (was 14 cells, HP290-20-6 or 7, I forget which, and Midifan) and the ducting matched to the fan better. It was stable enough in flight and looked great. Fit a HW730 on 24-28 cells, or HW750 on 30 cells, optimise the ducting and it'll fly like it a fighter and be a winner.

The photo below shows the take-off on the first retract-equipped flight. Chris hauled it off at too low a speed, the nose is too far up, the left wing is already dipping, and it bellied into the grass at the left, the long grass tearing out the mains.

Gordon
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Old Jan 26, 2004, 05:39 AM
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Gordon beat me to it.

March 2002

Wemotec midi fan (not mini as traplet claim) Plettenberg brushed motor 290-20-7 with 14 x 3000 nimh. Sping air 602 retracts.
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Old Jan 26, 2004, 06:51 AM
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Actually, power systems have moved on since Chris did the Sea Hawk. In fact he'd bought the Brushed Pletti maybe 18 months before that. A Midi with Mega 22/30/3 and 28 GP3300s, plus refined inlet and outlet sizes, should give this plane a respectable performance, even with retracts. Lipos might help with the weight growth.

Not every EDF jet flyer wants a plane that goes like a Bandito or Vector, and provided one was able to match Chris G's airframe weight so that overall weight growth was limited to that due to the retract and battery weight increases, a very nice-flying plane would result with that power increase (ie 28 cells x 45A vs 14 cells x 45A).

Regarding orifices, as it would be a slow-ish jet, FWIW I'd use a 100% FSA total inlet area, and 95% FSA outlet. A Midi has a FSA of 7.74sq in, so that makes for a total inlet area of 7-3/4sq in, and total outlet of 7.35sq in, ie individual tailpipe diameters of 2.2 in.

What REALLY hacked me off about the final crash was that the plane wasn't wrecked enough to preclude repair. All it needed was a new nose back to the inlets, and with the speed at which Chris builds it'd have been less than a week in the workshop. What totalled it was a glow flyer subsequently landing his model with the engine stuck at 1/2-throttle (dunno why he couldn't have flown the tank dry), losing control, and letting the thing taxi at high speed into the pits (I just managed to move my MiG 15 out of the way) where it tore into Chris' Sea Hawk and took out most of one wing and fuselage side

Gordon
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Last edited by Gordon; Jan 26, 2004 at 11:24 AM.
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Old Jan 26, 2004, 08:35 PM
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Hmmmmmmmm....I will order the plans and study them. I have no firm idea of what I want, except that I really like the Sea Hawk. Maybe a reduced sized one? Or maybe a larger one for turbine?
I don't really fancy a seven or eight pound jet with a midifan that puts out, what, four pounds of thrust, tops?
Funny, his Swift was the OTHER one that really appealed to me! I will order both. I just have a hankering for an all balsa jet right now.
The landing accident...ouch. That's why I really don't want to fly something like this when ANYBODY else is in the air. Seems like firing up your new scale twin is always a call for every Aerostar 40 trainer to fire up, too, and share the air with you...

That takeoff picture is funny! If you had no caption, I would be thinking one of two things was happening, either A) Chris Golds powered it with a BVM 91 and it is about to embark on a vertical climb, or B) THAT JET IS JUST ABOUT TO TIP STALL!
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Old Jan 26, 2004, 08:39 PM
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Was the prototype a twin or a single? Possible to put in two fans of around midi size?
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Old Jan 26, 2004, 10:15 PM
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Proto was a single with split intake and exhaust. Dunno what would fit twin wise.
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