John...these are the Cg details for my scorpion,, I cannot recommend that this is correct for all planes .... mine has P120 in the tail, the standard AD 2.2 litre tank, plus a dubro 24oz installed on the top of the main and a UAT mounted just in front of the fuse joining former, behotec gear.....empty mains and a full UAT, gear down ,... the CG finished up at 265 MM down the wing leading edge and 161 mm back down the fuse wing root just infront of the main gear struts the plane sat on its tail feathers without any noseweight and with eight oz 's lead and the wood tray and the air bottle it just dropped gently onto its nose wheel ...this is where we found the best flight characteristics,,, hope this helps......

Staale........ Viking disbeliever !...it really did fly at a slow walking pace as I said.... wait till you see one fly buddy.

Malcolm

Thanks for that. Mine is just about the same, CG is now set at 165mm back from the wing root. I was slightly worried that I had moved the CG behind the main wheels but with the model fully loaded the struts compress a little and this moves the wheel centreline back about 10 - 12mm .With the main tank full the CG will move forward slightly.

John

That was a new one.
It just seemed way to slow unless it was litterally standing on the jet eflux with a 60 deg. AOA.

Yeah. Hope to see one fly one day. No one owns one over here yet, as far as I know.
The lines on the Scorpion really appeals to me, but I'm waiting until the issues are sorted out. And who knows, maybe there will be a XL version for 160-180 engines one day...
Don't think I could resist a Scorpion XL for too long[8D]

Now.... back to building the Lightning[sm=pirate.gif]

Dear sap,


There is a XL Scorpion coming any time now buddy?

Great!

What's the vital meassurements and rec. thrust class?

I think I read earlier in the thread that some were getting longer wing tubes in the belief that because the wing would take a longer tube, this would strengthen the support of the wing.
Sorry to say that this is not the case.
I opened up the wing servo hatches to take larger servo mounts. Apart from the generous amounts of hysol (now removed) I measured the length of wing tube support. It ends 200mm into each wing.
A longer tube can be fitted, but the extra length sits in open air & adds more weight. The existing tube is in fact 20mm to long.

Regards

Jim

Managed to remove three ounces from each wing, although this will be offset to some extent by fitting standard size servos instead of minis.

Some advice for Aviation design. It would be helpful if the guy who makes the left wing, consulted with the guy who makes the right wing, & came to some agreement as to whether the wood blocks that support the flap & aileron horns are to be placed inboard or outboard. At present they each have opposite preferences.

Regards

Jim

I now have everything in place, using a Wren supersport, 2 X 5 cell nicad Rx packs & the ECU lipo in the nose. The Scorpion after all its mods weighs 18lbs 2 ozs & balances at 160mm with the gear down & a full UAT. No nose weight required. Standard size servos all round Except rudders (Hitec 225)

Regards

Jim

well done Jim , that the lightest I have heard of even with the lightweight Wren... you should have good flying machine ..let us know how it goes........best wishes....Malcolm

Happy camper

thanks to Jonny Hernandez, the whole world now knows how ugly I am and how pretty my pooch is !!! ...please note, even the dog has a Markham Park permit ! MK

Jim

I don't know how you have got down to 18lbs 2oz!!! I am at 22lbs with the Wren SS and 12oz of noseweight, of course I was unable to copy your weight saving mods as my model was too far advanced to go back and rip all the excess glue out. Taking the weight out of the equation you are 3lbs 2oz lighter than me using a similiar battery setup. I am using a 2 litre coke bottle tank and a six oz hopper and my CG is at 165mm . At 18lbs yours should fly very well, I hope to maiden mine at RAF Leuchars this coming Saturday if the weather is ok.

John

John. With no nose weight, I am immediately saving 12ozs. You would not believe the amount of Hysol I removed from each fin. It is also possible to almost balance the stabs by removing weight behind the mount pin. There is also some Hysol that can be removed from the wing. I opened up the inner face & removed lumps of it from the wing tube supports.
I used the optional kevlar tank & a standard UAT.
Good luck with the maiden flight. I am sure it will be fine. Sometimes a heavier model is more stable in flight. They tend not to get blown about so much with the wind.
Say hello to Ron Fraser & anyone else who may know me. They may not remember me as it is more than three years since I was in Scotland.

Regards

Jim

Jim

Ok I believe you! Ron Fraser flies with us regularily and I will pass on your greetings next time I see him (Maybe this Saturday)

John

Jim

Took the Scorpion up to our local field today as we had clear skies and NO WIND! although it was only 38oF. Purpose of visit was to run the Wren SS and do some taxi / brake tests. The Wren was reluctant to start due to the low temps. affecting the starting gas but a visit to the clubhouse and a kettle of hot water soon warmed it up! Wren ran perfectly after a six month layoff and fuel system checked out ok, only problem being fitting the glow driver between the plug and the side of the fuselage because of the plug position being at 2 o'clock on the SS. I will have to install a remote glow with a jack in the fuselage. Taxing / braking were fine and the Scorpion is now ready for flight testing hopefully this Saturday but the weather is again forecast as 30mph winds and rain.

John

John. Glowdriver? Are you not full autostart? Just get a barbeque lighter, turn on the gas & light it up at the tailcone. That is how I used to start my old Wren MW54.
My Supersport is back at Wren for some tlc after some damage in a crash. I will also get another for my Flash.
I hope the weather is kind to you.

Regards

Jim

Jim

No. My SS is manual start as I prefer to have manual control of the start sequence. Both my Wrens are manual start with on- board starter as this makes it easier for those of us who only have two hands! I am not a big fan of the match applied to the tailcone as again this requires an extra hand!

PS I forgot to mention that the pump I used had also not been run for six months, I decided to run some fuel though an open line to prime it before connecting to the turbine and I was amazed at how much muck came through the fuel line initially. I ran a couple of litres through it to clean it out. This may save some of you from clogging up your injectors in a similiar situation.

John

I have seen a P70 doing similar clogging because of the oil or kerosene . Anyone knows if that is typical or fuel related ??

I´ve been working on lightening the rear end of the plane , only remaining is to take out the fin tubes and fit a ply joiner and glue them . At this point the plane balances at 9986gr but no tanks . Hope the tubes weight a lot ......

Juan Enrique

Juan

You might end up with the ply tongues weighing more than the tubes, I think they have a pretty thin wall.

john

Maybe , but there is a lot of epoxy/microballons both in fins and in fuse that can be replaced by ply and a thin epoxy film .

I like a lot to modify airplanes . Finally I have to thank Eric Rantet for giving me a lot of reasons for having fun . At first we were quite dissapointed , now when we discover a new flaw or ocurrence we started to laugh........

Can anyone explain how to post photos , I had a couple of the elevator and rudder servos placed in an angled support at the front end of the turbine rails .

Thanks .

chichisport

To post photos click on the reply box at the head of any post, click on the "Click here to upload images and files" at the bottom of the reply message screen. Click on "Browse" when the box appears. You will then have to locate the photo you want on your computer, when you have found it click on the photo, click "open" and the photo title will appear in the "browse" box, continue with more photos if you wish, try to limit the size of the image to speed up the process, follow the instructions to upload your post.

John

Thanks John. Yours is looking good in the photo . Tonight I will try to post the "lightening photos".

Has anyone been flying thier Scorpion latly?? Is the weather bad everywhere? Sure has been quiet.


Hoss

My turbine had a small problem and i had to send it back to Jetcat they fixed free of charge with great service and it is now back so that 's why i haven't been up in the air lately and family matters etc lack of time plus i am painting the CT 114 tutor at the moment ... can't do it all ...... William Foster in CA has just finished his and he should be up for the maiden today if the weather permits,,,, MK

I am sitting on the couch looking out at what should be a clear but cool morning The scorpion is all charged up and ready to go. I reduced the nose weight to 7 ounces and my c/g is set at 161mm from leading edge, this puts it at the mid point of the main strut and I can balance her on the mains with the nose floating in mid air for several minutes at a time. Today is the day