He he, yes cold and lonely that's how we norwegians are :-) But you sure can fly a lot that way! This was after work one day, the only time I have been alone down there. So I have nothing to complain about.

New to Thread,
Great photo ela, you must enjoy flying your Hawk. It is sunny and 28 degrees in Sydney today

I have just ordered a Comp Arf hawk as well. This will be my 7th turbine build and i am really looking forward to it.

Guy,s,
Please keep the info going as i plan to add a few details [without adding to much weight] and hopefully she will fly as good as she looks.

Regards

John

Wow,
Was it something i said, 43 odd pages of usfull information and i make a into post and it all goes quiet.
David, do you sell scale upgrades for the Hawk ?

Can someone let me know what air valves you run for the Retracts ?
I plan to Fit a scale cockpit , Taylor Made Decals + add a Smoke system

Regards

John

John

Nothing you said!

The kit now comes with the fuse air inlets, only thing I did was dummy flap covers, but the moulding needs improving, we only made quick moulds and after 10 sets they are not great. They can be made from balsa which is glassed.
I used Jet Tronic valves as the air set CARF sell,many of my friends use a UP 3 valve. both work well. Use Robart rams as the manual, never had one leak!!
Derjet cockpit is the best I have seen, Powerbox smoke is my favourite

regards

Dave

Hi John,

I too use Jettronic valves on the gear ( 3 of them) as I have it set up to keep the main gear doors closed when the gear is down. Not scale, (except for the Goshawk) but, the gear can compress enough on a "heavy" landing to knock the main doors off so, I played it safe and kept them closed.

I orginally set up with a UP2 and UP4 to do the same thing but, although it worked, the gear didn't go up with any "authority" and if you had too much airspeed built by the time you retracted, they would often not make it all the way up and hang down. Hence the change to the Jettronic set up. Now they firmly come up.

Mike

Hey Mike I have the Up3 installed in my Hawk but have the same observation as you, They cycle nice on the ground but the pull on the gear when retracting is very weak, If i barely touch the one of the gears it stops until the rest is up then the pull gets stronger, but by then its out of sequence and the door closes with the gear out. I'm debating now if i should maiden it like that or just go ahead and change it out for two Robart Valves or the Electronic ones. I have a PowerBox Cockpit with the gear sequencer I could use if i go with individual Valves.

I have a video clip Ill try to upload on YouTube so you guys can give me your opinion if I should give it a try in the Air.

Kenric.

here is the Clip, please post your opinion.
Thanks!

http://www.youtube.com/watch?v=jfKd5q6WVm4

I have just watched your video and in my opinion they are too slow as with forward speed of aircraft they will struggle to lift up. I use 120psi plus I re-made the pinion shaft and bushes as I had mine pick up. Having the pinion and bushes made out of similar alloys not a good idea, so I made sets up out of phosphor bronze bearing material and made the shaft out of steel.

Mine locked up whilst setting them up before I even got to the flying field!

Alan

Just found pics of the new shafts and bushes I made sorry they are out of focus..

Alan is right, they are too slow. I had mine set up to go operate slowly for the maiden flight and they would not go up. I adjusted them to go up as fast as possible and come down a bit slower and it worked perfectly on the air.

Just open the needles for up going gear. We have had no problems, the UP valve does require a leak free system to operate (any bleed through on the cylinders and it won't work)
Biggest thing is people taking off too fast, pulling hard (climbing) and expect the gear to work against 2-3 g! Even on short grass strips I rarely reach full power on take-off, on a runway I'm normally breaking ground at 2/3rds throttle on a P-120SX!
The angled out leg doors with good airspeed will cause problems...even the full scale has a max speed for gear actuation

Dave

Started on the Hawk, my rudder servo opening needed to be cut (5 min job) and the rudder was loose so be careful when you remove the tape it doesn't fall on the floor! There is a brass/copper colored bubble wrapped wire which is probably for the hinge (it looks the same as the gear door hinge wire) but the diameter is smaller than the rudder hinge holes allowing a lot of slop so I replaced that with a larger diameter music wire for the rudder hinging. Someone earlier used CF rod which is light but wouldn't that wear over time?
We all have to keep after Dave to make more of those dummy flap hinge covers, no reason why he should have the only really cool looking Hawk I am way too lazy to mold them myself!
My buddies have told me to get it in the air first and then worry about the scale details. But some things are good to have, I got a Derjet cockpit and BVM pilot figure so I know where to mount things and how to adjust the CG. But Scale details like rabbit ears and hinge covers and repainted fins for stickers can wait until it is flying.
One last thing I will certainly install the wing fences and fuselage strakes before flying as they impact the flying qualities of the jet.

I want to revisit one subject. Mounting the turbine. Options are above or below the rails/with or without packing. In either case I expect to use a throttle to elevator mix for when I pour the coals to my Cheetah. It's been a few years now since the manual was written, we all know Dave has build and flown a bunch of these planes. Where would you put the motor?

When I mounted my 120SX i turned up a plug to fit the exhaust and that was glued centrally to a ply disc that fitted the bell mouth. I found it was out so I fitted some 3mm ply as in the pics....

Alan

Also I used a 2.0mm carbon rod for hinge pin (mine was missing in the kit) and when I took out the rod whilst I am re-painting there was no wear at all to hole or rod.

You want the turbine as high in the fuse as possible. I raised the elevator servo mount 10mm after my prototype model, but the outer cool wall still interferes with the plate if you raise it right up.
JetCat have the offset mount...so this makes a difference.
Some of my guys have mounted JetCat turbines on the other side of the rails (top in the real world) I guess Jet Central turbines have no offset on their mounts?
I guess is need to measure an exact possible centre for the front of the tail pipe, but I'm not due to start building another of these until I have finished 2 Ultra Flashes I now have to build (and a bunch of stuff to finish too)
I have a friend building one now...I see if I can get a measurement off his. If you were to mount the carbon half duct above the rails, screw the cone to that and centrally mount the turbine in the tube it would be about right.

Dave

Thanks for the input guys its much Appreciated, Ive decided to order a BVM HiFlow valve for the Gear and a Robart Blue valve for the doors. A friend of mines that bought a Hawk from a Member on here has these same exact valves and i have flown his hawk and the gear works perfect. I still might just give the UP3 a try on the maiden, depends how it look after I try some more adjustments on it.(I've tried but ill give it a try again).

Kenric.

Just another thought. Mine were hanging up sometimes and what I found on both mine and my flying buddies was the track where the round tube slides in were not quite wide enough and it would hang up a bit. We took a dremel and cleanup up the machined slot just a bit and now they were very smooth.

My 2 cents

I have seen units with the sliding bar wider than the frames, in this case you must ensure the wood rails are clear of this or it will cause problems.
The UP valve works great. When you adjust the needle you need two tools to tighten, one to hold the more open position and one to tighten the locking nut.

Dw

Hello Dave,
                     Is the CARF Sport retract set my only option ? The scale legs do look better but the price seems a bit extreme. Are you happy with just the sport legs ?

Regards

John</p>

Really yes, nothing else will fit. The Scale legs are a work of art and a huge amount of machining.
The sports gear works perfectly and looks fine with the leg covers fitted.
I have a tonne of flying on mine grass and tarmac no leg problems.

Regards

Dave

Thanks Dave, I will post some pics and measurements when I am done mounting the Cheetah and thrust tube as high in the fuselage as possible.

I mounted my Cheetah below the rail(with the fuse upright). Had to extend the rails as the tabs on the Cheetah were too narrow. I haven't had many flights yet but I don't seem to remember it needing trim at different throttle setttings. Maybe I was so impressed with it's flying qualities I didn't notice.

Marty

I see there is focus on thrustline to minimice trim changes at different speeds. Every pilot is different and must decide what he want. But one thing is clear. No matter where you put the turbine you will never achive a total neutral plane. And when rising the turbine you must be aware what can/will happen when applying thrust after a slow by or a to hot landing approach.

You should also consider moving CG bakwards a "couple" of cm behind what says in the instructions.

My recommandations is leave the thrustline as it is. Use flight modus and throttle to elevator mix with delays.

This is my experience after 150 flights with focus on traditional aerobatics.

The Hawk is a fantastic airplane :-)

The thrust line is critical if you really want a near neutral aeroplane. I have flown lots of these Hawks, test flown 10+ and the thrust angle on all the production aeroplanes is much better than my own model. None of my circle of Hawk flying friends have mentioned any concerns, though I have advised on turbine mounting on most of these. Mixes are not as good as a correctly set up "mechanical" thrust line. So many things affect it (flaps in the Hawk vary on neutral-by peoples building) but there is no reason why it can't be near perfect. I'm guilty of not coming back to this and placing something in a manual addendum...so I'll do it!
I will have another Hawk to test fly in the next month, so I'll concentrate on how it behaves, it will have a P-140RX for power.
Mixes rely on timing, everyone has different throttle action habits, speed etc.

Lets get a fixed number for the front of the pipe from the fuselage top centre line (its the easiest datum) and then everyone can work from that.

Dave

Someone asked a few posts back how the small front door had been done, just came across a pic of how I did mine

Alan

Beauty work Fireblade5437, how do you do it... so good?