Alex48

Hi Jack

Thanks for the heads up, I'll get onto it.................funny you should mention the wing roots, I was just looking at these thinking they need some reinforcement. I've also just installed some extra BVM canopy hooks but will reinforce the area you suggest too. I'd love to see some pictures.................

Good luck with the maiden! I'm told they fly very well.

Thanks again

Alex

Alex48

I just wanted to mention a problem I had with mounting the stabilizer bearing block. I noticed the sides of the fuselage were bulging out close to the bearing block. A little investigation discovered the aluminum bearing support was digging into the fuz. i didn't notice this problem when I first attached the stab because there was no compression of the glass, It may have had a small amount of glue supporting it and the constant bolting/unbolting must have dislodged it. When I checked the structure I made certain there was a 1/4 inch ply plate bonded into the structure at this position. The problem is that the ply hasn't been glued flush with the fuz. The forward holes are fine but when I opened up the rear mounting holes I found there to be a 6mm gap between the top of the ply and the start of the glass fuz. To solve this I used 3 large penny washers ontop of the ply so the stab has something solid to bed down onto. While I was working on the stab I carefully checked the geometry of the servos and linkage with a laser and finally bolted the 8711's down.

The touching up on the paintwork was done by SM, it's a bit messy yet to sort it out......just thought I'd mention it in case you thought I was getting messy.

Cheers, Alex

Jack Diaz

My Feedback: (1)

some pics

Jack

Alex48

Great Job..........[sm=regular_smile.gif] Like the color scheme too!

Cheers, Alex

SAP_2000

I also hate that the slams up and down. On some planes you almost expect the gear to come up through the wing as it slams so hard. Can't be good for the gear mechanism or the gear mounts in the wing.

To solve this I restrict the airflow of the exhaust port on the valve. It is much better (IMO) to restrict the exhaust flow as it makes the gear go really slow and smooth, but still with great force so it almost looks hydraulic. When you restrict the in airflow the gear tend to move irraticly and with out force.
On the jet-tronic valves for instance, I blind off one of the exhaust ports and install a festo fitting (M5) in the other. Insert a short piece of festo tubing in the fitting and slide a M3 wheel collar over the tube. Now you can control the flow and make the gear go as slow as you want by turning the wheel collar screw.

I'm sure there is an an exhaust port on the EV5, but you may have to thread it to install a fitting, or glue an air nipple in place with epoxy.

I have used this method on all my planes for many years, and even big heavy gears come up in a slow nice manner.

Looking forward to getting mine[8D]

SAP_2000

No engine in there? [:-]

Jack Diaz

My Feedback: (1)

Staale, I agree with you in restricting the exhaust flow of air instead of the in airflow.
That is what I do in most of my planes.
The problem with some planes (and, according to Ali, this is one of them), you really need to slam it "up" with lots of psi (about 120), or they will not retract in flight.
In other words, you want "Unrestricted" flow going up. So, I needed to slow down the "down" part of the cycle only. And what I described was the only way I could figure it out (using the airpower valve) Any ideas??


Anyway, I will know when I fly it. Depending on the required pressure to retract, I may change things around

Jack

Jack Diaz

My Feedback: (1)

Staale, the engine was installed and ready to go.........(Jetcat 160)

I did't forget it ...LOL

What I forgot, was to "tighten the fin screw". And to do that you have to take the engine, bypass and pipe out.

At least I am glad I remembered that, before going to the field.

Jack

SAP_2000

Just wanted to make sure you did not try to maiden it without the engine

I think that enough pressure is the key to safe retraction. If it does not retract well @ 120psi, the cylinder/ geometry is not right IMO.
I use 120 psi in all my planes and like to use large and maybe even 2 large air bottles so the pressure does not drop that much when retracting.
I always test the system @ 140-150 psi regulary so I know it will hold up and use 120-130 psi normally.

To have induvidual exhaust flow control, the UP valves all have it. I am going for an UP-3 mechanical sequencing valve in my Hawk.
If you don't like the UP valves, you could also go for the normal red Robart valve that also have seperate up/ down exhaust control and a sequencer.

Robart valve: http://dreamworksrc.com/catalog/prod...roducts_id=746
UP-3 valve: http://dreamworksrc.com/catalog/prod...roducts_id=740

Ali

My Feedback: (5)

The issue with the gear on this model is as follows.
First off the main door rams are just too thin and weak. I replaced mine with a pair of Jet 1a big boys which work great.
Then the actual gear itself was a pain to get retracted, even though on the ground they worked fine. I sort of cured this by doubling up on the large air bottles for the gear only ( Increase volume of air ) and ran 130 PSI This worked better but still had the odd issue in the air.
What it turns out to be is the speed at which you are flying when you cycle the gear.
I found it on the big Skygate hawk. If you left it too long after take off and the speed built up then no matter what pressure you had the mains would just not go away. Even flying inverted ( Which normally gets any troublesome gear away ) did not help. I think the slightly outward facing doors attached to the main gear cause so much drag that as the speed builds up the restriction is too much. So now what I do is take off, as soon as I am off I throttle back a bit, slow down and then cycle the gear. Hey presto 110 PSi and it works every time.
Hope this helps?
Regards Al

pilot tw

Hi, Jack

Thank you for posted these pictures,

i saw you used the 2 x L elevator horns for 2 x elevator Pushrods is better than the Single L elevator horn, I also used this way for my prototype,

I will ask the Morne for modify our manual for this way, Thanks a lot for the remind,

Best regards

Anrton

ColinW

Re Ali's comment on speed above. All full size have an airspeed limit for retracting the gear - for instance the Jet Provost has a limit of 125 knots for raising the gear, but once down the limit becomes 140 knots. The Lightning (250 retraction and 280 with it down) nose wheel retracts forwards - if the gear is not selected up quickly enough the airflow prevents it from retracting, and you zoom skywards with the nose wheel sticking down - this always leads to ribald comments from any mates who happen to witness the event! Perhaps we are asking too much of our model systems (flaps also are limited to avoid airframe damage and having too great a pitch reaction), and we should make selection of the services at more modest speeds?

Ali

My Feedback: (5)

Colin, Just out of interest. Did this ever damage the gear on something like the lightning if it were to hang down?

Alex48

That does look a better set up than one L bracket. I only had one included though so did as the manual suggested.

Alex

ColinW

Hi Ali, No you just had to slow down to about 220 knots, and the nose leg would pop up. It was just air pressure overcoming 3000 psi of hydraulic pressure. I suspect that the doors and leg might get damaged if the speed was allowed to increase too much. I think there is an example on U-Tube of a four ship take off from Wattisham where one of the aircraft's nose legs sticks down.

pilot tw

Hi, all Hawk fans

after the Chinese new year that we will release more color scheme for Large Hawk 100 & Large BAe Hawk , we just finished the marking and some decals....

http://www.skymasterjet.com/bigbh.htm

Best regards

Anton

ZivBit

This got to be the best looking color scheme I have ever seen in a hawk....
I will place an order soon Anton...

Do you have more pictures of the top and bottom wings and tail?

Ziv

pilot tw

Hi, Ziv

Please see this thread for more details:

http://www.rcuniverse.com/forum/m_94...tm.htm#9461282

Best regards

Anton

Jack Diaz

My Feedback: (1)

I maiden mine yesterday.
Flies very precise and elegant, and it's easy to land.
Knife edges are unbelievable. Just a little coupling needed.
Gear worked flawlessly every time. Retracts with as low as 70 psi after a dirty fly by.
I am attaching a pic with the neutral position of the elev for normal flight, take off, and landing.
Flew with JC 160 using full bypass. Only needed half power for most of the flight. Plenty of power for verticals and go arounds. High speed passes at 70% power at the most.

Couple of tips:
-Recommended CG feels nose heavy. I moved back 1 cm (21 cm from LE) and feels much better. I will try moving it back further.
-I think that the recommended landing flaps (45 deg) are too much. Makes the plane very unstable at low speed. I reduced to 35 and improved a lot.

Jack

Alex48

Well done Jack!

The only problem with being a builder is that I never get to have a play with what I build

Glad it flew well!

I'll try and update ther thread in the next few days I've done lots since my last post.

Cheers, Alex

Alex48

Thought it was about time I updated this thread. January's been manic I went from having very little on to having models coming out my **** and my other job demanding loads of time in Germany. Better than the opposite though! .................anyway this is where I'm at.

The rudder was installed using genuine Robart hinges. The Skymaster hinges always have more slop than the Robart ones. The pivot point for the bottom two hinges is a little way behind the fin so these require support. I use brass tube for this which strengthens them nicely. This is relatively large model with a big fin so it's better to be on the cautious side. The fin has a neat method of attachment, It's just a matter of sliding the fin on and tightening the clamp around the large carbon peg. The only down side is you have to remove the turbine and pipe to access the bolt. I might make two little access hatches to make life easier but haven't looked too seriously into doing that yet.

The rudder servo is in the fuz on a push pull arrangement. I've used heavy duty ball links and carbon tube to make the linkages. You have to use ball links as there's a large angle between the servo and rudder horn.

The pivot point of the rudder didn't line up with the hole provided so I had to make new hole for the metal shaft that actuates the rudder. The movement would have been very limited if I hadn't done this, because of the geometry when you moved the rudder too much it would move the entire fin as the linkage started to bind. None of this was acceptable so I re did it.

Cheers, Alex

Alex48

These skymaster cockpits are great, I really like the seat detail and the atmosphere both create once installed. My only problem with them is the material used is so brittle that they are nearly always damaged and this one was no exception. The best way to strengthen them is to glue 1/32nd ply under the lip and then make a fillet of epoxy around the edge. After this they're strong enough to mount directly using the cockpit flanges.. Both cockpits will be mounted inside the canopy making access to the equipment trays easy. I repaired the damage which involved some filling, sanding and a re-spray then painted the inside of the canopy frame a matching gray. It's very difficult to bond anything to the plastic SM use. You only have to look at the seats and they fall out. The best stuff to glue them back with is UniBond clear sealant.
The cockpits are then secured inside the canopy frame with tiny countersunk self tappers.

Alex48

Onto the turbine and pipe installation. There were no turbine mounting rails supplied. So I made a couple of templates and cut some good quality 1/4" ply to suit. These were then bonded into the structure with hysol. I've used lots of methods to line pipes up with turbines, lasers......jigs........and so on......... But the best method for me by far is to just look down the pipe and line it up by eye. The pipes then secured onto the sides of the turbine rails with some hex head self tappers. When I put the pipe in it hit the bottom of the fuz at the exit. I had to dremel the aft former to centralize the pipe with the hole in the fuz with this done I fitted the turbine and spent awhile cleaning up and fitting the carbon bypass which is secured with four hex screws. I was waiting for one from SM but decided time was running out so I took one that I was yet to install in one of my own models. I don't fly much anyway

Alex48

The batteries on this model will be two 4000mAh Dualsky 2cell Lipos in a hard casing, these are primarily used for RC cars but will do a grand job up in the nose of this model to help with the CG.
The ECU will have a JC 3300mAh lipo and finally the lighting will be powered with a 6v 2500NiMh. I've made four ply battery boxes that are hysoled into the nose. Hopefully this will avoid any ballast.

I couldn't resist putting it together for a gander. It really is a great looking model. Skymaster have done a great job producing one of my favorite marks of hawk. I like the size of it too should have a nice presence once airborne.

Well the paints nearly dry so better get back to it.....................

Cheers, Alex

Jack Diaz

My Feedback: (1)

Alex, initially I put all the batteries in the nose.
After the maiden I had to move one of the receiver batts. and the ECU batt. back under the cockpit. It was way too nose heavy.
I suggest that you don't glue the battery boxes yet until you balance. They may not end up in the nose.

Regards
Jack