At least you didnt pile it in! glad to hear the first run up was relitivley ok. Let's hope the late night building doesn't catch up with you next time you take it out to fly.

SJN

After watching all the work on this thread, I could hardly believe my eyes when I saw those wings without their fences. I think your guardian angel must have been working overtime to blow the receiver!

At Abingdon yesterday, I spoke to no less than two former Hawk owners, whose models had turned turtle on take off. Each admitted to an absense of wing fence. Make them a bit oversize for safety.

Listen to Henry, He knows what he's talking about. I'm eager to get my A-4 flying but i'm methodically going about the installation of all the systems, trouble shooting and anticipating as I go based on former expierience and basic mechanical aptitude. Each system must be completely reliable before moving on to the next. The great thing about these ongoing conversations is you can learn from what many have already learned the HARD way. DB

SJN

After a nights sleep you might consider it an good result for a first maiden outing. The simple mistake, which everyone makes from time to time, at least it was not fatal for the Hawk. On the latest hand written updated building notes from Dave at Colchester he recommends making Wing Fences, from a balsa outers, ply middle sandwich construction. Logically I doubt he would recommend something that was not functional, give him a phone to check, he'll appreciate your comments on the JJ experiences. Andy is back working with Turn and Burn the JJ UK rep so all is looking good for us as JJ users. Time enough till the next meeting for you to write a start up check and prep list, open valve, safety to ON, prime fuel line. I can then borrow it, as my Hawk should be ready to fly by the time you go out flying again.

Thanks guys. Ill install the fences.

Sonnich, are you sure your receiver is cooked? You may have just shorted the battery cells and of course the recvr. would not function after that. Try new battery. My charging switch is set up so when switch is off you plug into charge receptical. This is direct connection to battery, recvr. is off and isolated. Also if I try to insert the plug in reverse polarity nothing will happen as they use the standard three wire connector with only two wires, plus and minus ,run to the center pin and one outside pin. This way a backward connection does nothing. I hope it's just the battery .Contact PJP Jets about the wing fences,maybe they have a pattern you can use from their small Hawk kit. DB

Hi DB

the RX is cooked..... I tried another batt.


I have no idea what happenes inside my switch with the charge jack. I messured with a multimeter, and when you plug in the charge lead something happens......and it fried my rx.

one of my friends did this last year to his futaba RX too......must have been the same crappy switch he used as me.


Ill cut my own template for the hawk myself. Just need to find some pictures. I was thinking of using some 5mm thick plastic card for the fences.

These look ok ?

I added a template for the fence a few pages back.

Dave, I think it looks too tall....but it would probably work better...


heres the wren Hawk...

too tall? it's scale.

SJN

I like Pic3 best. A little over scale is no bad thing. When you know the model and have a 100 flights under your belt, then think about shaving it back to scale! Thorpe will tell you the same thing on their Hawk.

Remember you have a few handicaps on this model - namely the tailplane is operating in a very different manner to the full size and any helping hand you can get must be a good thing.

On that maiden flight, use very little flap and as much speed as possible before you rotate. Rember climbing into the air with the help of the flap (eg.to get off grass quickly) can leave you with insufficient aileron authority and the result is usually fatal. Lots of speed equals safe.

Good luck.

Thanks Henry

Ill remember that [sm=thumbup.gif]


all 4 pictures above in my post are of the same fence. Why do you like #3 best ?

How is it so different?

SJN

Maybe it is trick of the camera but to me it looks that fraction wider all round than the others.

Slick33

The tailplane on the full size rotates around a point substantially below the root wing rib and is mass balanced as well. I enclose a photo of the full size, showing the wing pivot. I have an AMD and a PJP Hawk (which replicates the full size and is shown below) and the different motions are immediately apparent. The flight characteristics are surprising different as well.

SJN You may want to adjust your stability delay on your ecu, this could cause the inability to run at the prescribed rpms of 44,000. Email [email protected] and maybe he can give you the values he is using. Hope this helps. Russ

SJN

What length of pipe do you recommend, as yours looked just short at the tail?. What gap did you leave between pipe and the JJ1400 turbine? I'm going for the Orbit pipe so shouldn't get any JJ notes Putting in so night shifts on the Hawk to catch up [&o]and get some summer flying. [8D]

Paul

Thanks Russ, ill fiddle with it next time.

Paul, I bought the short one from wren. But it was too long, and I cut a few cm`s off of it.......and then it was too short because of my my case. The fuselage was cmistake. :-)
But I realy dont think it matters anyway. It was cool at all times, even with the less than perfect startup.
I have the one piece exhaust cone of the turbine 10mm from the bellmouth of the pipe.
I have not messured the thrust, but I can feel it has almost too much for the plane

Tailpipe stopping 2cm or so short of the fuz exit is not a bad thing. It improves the cooling of the pipe.

You learn something new evey day, but how does being 20mm short in the pipe help the cooling when the pipe end is inside the fus? Surely 10mm sticking out the back end will have more effect towards cooling. If you do have a wet start any unburnt fuel inside the pipe as you tip it out the Turbine might run through the pipe and make its way back into the rear end of the fus if it not completely sealed. Just asking as most of my turbines are outside in the air or the turbine is at the rear end of the fus.

Paul

Hopefully the venturi effect should suck it all outside the fuselage.

But if fuel is dripping and running down the pipe, you are SOL. [8D]

Hopefully the magnetic valves will prevent wet starts........Never had one on my simjet yet, which has the same ECU.

SJ,
I need a picture or the ECU + Handheld device ASAP please
I need in the next 10 mins (for my DT project)

You have already got them on your site mate

ye lol.
My site is blocked from the school network....
I wonder why......

Thanks alot mate.