After 11 years and 600 plus flights my old hawk (who is now owned by a friend) has developed a leak in one of the air tech retract cylinders.
I’ve seen some folks on here (Marty) have replaced O rings. I had the retracts apart last night. However I cannot figure out how to remove the piston. There seems to be a cap with no way to unscrew it. Any tips or info on how to take it apart? Thanks.

Large or small cylinder?

They unscrew from the block. Lightly warm the aluminium with an air gun.

Not sure Dave, it’s one of the mains. I’ll attempt to post some photos.

Hello

Dear Builders.

I have started a build of my comp arf hawk a couple of years after I bought that kit. This is an awesome thread, however, I am not very clear about a few things . I hope some of your experts can help me.

1- The thrust tube is passing very close to the elevator servo plate. Is it recommended to use some kind of insulator to protect the servos ?. I am using the CARF thrust tube.
2- The thrust tube cone does not fit centered in between the engine mounting rails. Bigger portion of the diameter stays under the rails. Is this OK?
3. With plane upright, should I mount the engine on underside of the rails? ( seems there is no other option if the engine exhaust cone has to center in the thrust tube cone)
4-There is no wooden former to hold the thrust tube in place on tail end. The tube is held in place by the fuselage. Is there a fire risk there due to hot thrust tube ?

thanks in advance

The pipe is twin walled, so the air being draw down the gap keeps the outer wall relatively cool. The thread starter Hawk is still flying 15 years later, same servos as built with and I’ve never had the pipe out. My pipe is hard against the elevator servo plate because I raised the plate on production kits after finding a thrust line change necessary. You could either paint the bottom of the plate with BVM heat shield, or use some Alloy tape as a reflector shield, but it is not critical.

Thrust pipe cone position at the front could do with being centred on the top (sitting on wheels) of the turbine rails as it’s always needed a little down thrust for perfect trim. Then depending on your turbine mounting strap, mount the turbine central on the cone.

Again because the outer wall is cool it just slides into the rear hole.

Dave

Hi dave thanks alot for your quick reply . Very much appreciated . Is it possible to post a picture of your turbine install and the thrust tube carbon cone install ? I am little bit confused on the point of these two items. I see the point you are trying to make but really the thrust tube is literally pressing agains the wooden former in the tail of the kit and there is no way it could be centered on a turbine installed on top of the rails . It would be very interesting for me to see how you have done it.

Hi

Maybe these photos will explain. As Dave mentioned you want to get the turbine 2 cm higher than mounting rails (upright position). The reason for this is that the thrustline in this model is wrong.

The pipe/cone is fastened to the rails. The pipe outer pipe wall will touch the servo mount, but this is ok. I even sanded away some of the bottom former at the servo mount to get the pipe angle as i wanted.

In the rear you just let the pipe run through the model. No mods needed

Eirik

Very nice turbine of the Bae Hawk, it will definitely be a lot of fun...

Had a pleasant weekend at a Scale Airshow in Norway. What a bird!

Nice job!

Good day jet guys . Landing flaps what’s the maximum mm for landing? You can email at [email protected]
thanks

E-man 1, Thank you very much and sorry for the late reply, I had to stop all build activity due to some personal issues, My hawk build has been on hold in the mean while . I will restart now.

So it’s very clear that the turbine has to be installed 2cm above the mounting rails , with plane upright. I see that you had to make a slot through the mounting rails to uninstall the turbine. I will be using a Kingtech 140G5 which is significantly small and easily passes through , in fact I will have to build rail extensions to reach the turbine mounts.or vice versa.

This is very nice cockpit. Is it drop in fit or you had to do some work on it. I will really appreciate if you could let me know what was the weight of this half cockpit?. I don’t see it on their website anymore, nevertheless I will send them an email about it