Dave Wilshere

Yep, 205mm is about right.

izzy

speaking of CG , I have mine ready for maiden hopefully this week
to get the cg to 205 , need to add aprox 500-600 grams of weight in the nose
does this seem right ?
have note done a cockpit yet , and install was basically trying to copy DW
I also hope the thrust line will be ok, as I mounted mine on the original rails

Gary Arthur

My Feedback: (29)

See post 1834.

We are flying ours with a CG of 198 and it flies great. Plus it lands like a putty tat.

I had my nose weight fall out on take off (long story) and with a CG of 198 and the nose weight falling out it still flew and landed but was pitchy and floaty on landing. I can only image where the CG was with 1 1/4 lbs falling out.

If you are starting at 205 it is conservative. you may find it will land a little slower with the CG up at 198.

izzy

Mine will weigh In at Aprox 28 pounds dry with the ballast up front.
So from what I read some planes being 29 pounds I adsu
e that's ok ?
thx

Matt Smailes

Sounds like a wide range of weights and balances are acceptable. I like the idea of floating in on our grass patch.

izzy

Matt
What does yours weigh in dry

afterburner

My Feedback: (18)

A little crow will help it settle in on landing. Sometimes it can get a little floaty in ground effect and get too slow dropping a wing about a foot or two over the runway. The crow seems to help avoid that.

Dave Wilshere

Hawk was laid out to balance with a cockpit install and 1 pilot. I worked on approx 450g for these. With the DerJet cockpit and a Skymaster type 1/5th pilot its normally perfect.

Never needed to run CROW on a CARF Hawk, but that does not mean you shouldn't. I have enough flap that's its all drag and it does not float at all and mine is super light (27lb)

Dave

jjantti

Hi all,

First thanks for all this very informative thread. It has been priceless while building my first turbine.

I got mine on the eve of christmas and I'm almost at the maiden now. Ground tests went fine and now with proportional brakes it should be perfect. Just need a good day of and desent weather. And of course that repaired electronic valve back from repairs.

No paint nor cockpit yet but those are secondary to me just need to get it flying soon. Just 4-channel light kit and basic good quality build. Installed M140XLB on top of rails as written here. Reinstalled it again when realized nose ballast needed. Now with bit longer and much lighter Grumania jetpipe and engine as far forward as possible. I still added 250g lead to the nose. Main tank is also reinstalled and leaning against rear former now. CG of somewhat 195-200mm was the result. Should be good for maiden and can be removed when I find the time for the cockpit. AUW is now 11,8kg UAT full.

I have some scale details added but still need lot more. Those rivets look great on the rear fuselage Matt Smiles! What technique did you use?

/Jyri

izzy

I weighed it in all up weight is 15,6 kg. is this crazy ?
Dave if yours is 12.3 kg. mine is a PIG
needed 550 gr of weight CG 200mm behind front of wing

izzy

One more question. How are you all holding the turbune mount under the rails ?

How do you get to hold the nuts?

Dave Wilshere

What servos you have in the tail? That's a lot of nose weight, but its still going to be 15kg without! You could order a Grumania tail pipe that would save a lot over the stock pipe.
I've flown one around that weight, will fly very scale with the mass, have a nice sit in the air, just don't try and float it in to land.
Mine is very light.

izzy

I have 2xJR 8911 servos for the elevator and Savox 1256 for the rudder
whats the average weight of these planes dry
I have a KT140 G installed
Powerbox pump and carf flash main tank for smoke tank above the main tank (when the plane is sitting upright )

Dave Wilshere

OK, little heavier than my plastic cased 8711.
29lb
Turbine is a little heavier, I have no smoke system.
It all adds up. In the mould paint verses your painted scheme is big too

jjantti

izzy and Dave Wilshire,

I have 2x Savöx 1268 (2x62g) and Power HD DS-8325HV (80g) on the back so I don't think it needs lead because of tail servos. But just like said earlier Grumania tail pipe looks superb and is 200g lighter. It is few millimeters thinner so new plywood former is needed on the back tough. Because of air gap exhaust also looks more scale now. I ordered mine tad longer and installed engine as far forward as possible and saved some nose ballast there also.

I have glued aluminium blind nuts on plywood for the turbine screws. Otherwise main tank would be on the way.

/Jyri

Matt Smailes

Have not tried it on the scales yet. When I'm next in the workshop I will weigh all my painted assemblies and compare with an in the mould hawk to find out. I really want the scale mains on mine so may look at other ways of saving weight such as a custom thrust tube, and a lighter cockpit if it's really bad.

Matt Smailes

Thanks for the complement, after trying all sorts of glues and applicators Dave suggested canopy glue one day at his shop. Here are some photos that explain how it all happened.

jjantti

Thanks for the pictures Matt. So they were droplets of glue! Not sure if I have the patience to match yours but I definitely will give a try. Now I know the best glue also

/Jyri

Dave Wilshere

The way we do it with a pin wheel. Different types, but grind the points off, make a stand off straight edge and put the ZAP 560 in a thin tray, Roll the wheel to collect a blob of glue. Place and roll.
Takes a little practice, but works well and V quick. If you mess up you can wipe off with a damp cloth and carry on.

Dave

jjantti

Thanks Dave, I'll give a try. That would help keeping rivets uniform in diameter and specially in spacing. Diameter and height was my first fear with my set of nerves combined with syringes.

Replaced valve arrived today and weather forecast is not that stormy for the weekend... I actually have friday off. I'm running out of excuses

ps. You wrote a great manual back in the days.

/Jyri

Dave Wilshere

Thank you
I should write an update sometime, there are things I missed and more info available now after 6 years.

jjantti

It has flown. It needs small repair. It will fly again. I'd call that succesful maiden

My first landing maybe was not the best and gear doors took some hit. Full landing run in 40cm! Atleast gear is sturdy! Why is it that you'll always hit to the worst possible spot... red lines are the skid marks. Well that is just glue and few hours. The left middle main gear door was lost must have fluttered into woods or something. Now it will do without the doors. Still full of mud


For some reason I had to calibrate my stereo vision for first three landings. They all went on the same side of tarmac. But from fourth and so on that seemed to be ok too.
https://www.youtube.com/watch?v=WYA4TRpeB6A
https://www.youtube.com/watch?v=Y_a0kvKZtJ4

/Jyri

izzy

Question:

when setting the the flaps do I need to get to mechanical lock at full
flap.that is servo horn and pushrods are in line with each other ?
thanks

izzy

Anyone ?

Dave Wilshere

Its the optimum arrangement, for low power use, but huge holding power servos cope even with the worst mechanical set up