Probably!
It looks good

Lasse P

LOL Lasse

Knowing Julian well, I'd guess it because it slowed the build down so it delayed the actual flying part of the hobby

Just wanted to add a bit of scale detail to such a nice kit, and make mine a bit different to those already out there.
Was inspired by pics on here:
http://www.viper-aircraft.com/
Gallery
Mk II

Need to decide what colour to paint the NACA plates (pink ?), recessed grille mesh and whether to weather the engine ducts.

If I really wanted to string out the build Dunc, I'd implement the belly air brakes

Like this....

did anyone install the rudder servo in upward direction (not like the manual)? i want to put a Y lead between rudder and the NWS servo and that looks the only orientation that they could work in same direction with.
kaon

I am about to maiden my 2M Viper, CG is 20 mm forward of the main spar.  I have searched here, but not found whether or not people are mixing in any (presumably) down elevator with flap extension. My flaps come down 35 and 65 mm.
Should I mix in some down elevator with flap extension, and if so, how much?

This thread has been dormant for awhile, anybody doing anything ?
I just received a new Jet Central Cheetah so it looks like I have to get back to work on mine

This plane and the Viper MKII (big one)fly VERYWELL!!!.
ENJOY
see http://youtu.be/M-iUzMtMToE

Rich,

You should have gotten a JetCat Cheetah. I hear they did very well at the JWM.

Enjoy your new engine,

Jim

This is my first tail pipe installation so I would like to see any pictures of a stock installation if possible. This is my second jet. My first was and still is a facet.

Thanks in advance.

Skydell I have been flying my VJ 2M with no elevator mix to the Flaps, and my CG is set to 12.5mm from the main wing spar.
I have found this to be the perfect CG for my flying style, verry little elevator is needed in inverted flight.




Alan

Thanks Alan for your post.
Since my initial question about flap/elevator mix, I've flown this ship 15 times. Initial flight was, as per the manual, with a CG 25 mm forward of the spar. I found it quite nose heavy, and shifted the CG back to 12mm forward of the spar. This was perfect. I had also set in about 1/8 inch of down elevator mix with full flaps, and actually had to change that to a trace of up elevator mix. Now flight characteristics are stable and excellent.

One interesting thing I've noted is that with flaps down at 35 mm for take off (as per the manual), the nose wheel was hard to rotate, and actually seemed to be "wheelbarrowing" on the runway. I changed to taking off with no flaps, and that stopped that problem. I may try taking off with 20mm of flap now, because it takes a fairly long take off roll to get off.

An additional issue was that the upper fuselage was heating up severely during taxiing in. I have a Jetcat P-80 SE with stock pipe, 3/4" between end of engine tail cone and front of pipe bellmouth. I cut the cheater holes in the bottom fuselage, between the strakes, as suggested by prior posts, and they helped only slightly. Then I mounted a 0.016" thick aluminum plate covering 1/2 the diameter of the inside of the upper fuselage as a heat shield, and that cured the problem.

All and all, an excellent flying ship that I am completely delighted with.

Tail Pipe help.

Mytail pipe is about 1-1/4" too long with the engine all the way against the intake ducts and 20mm gap between the exhaust cone and the front lip of the pipe - Without the bell mouth.
I can move the engine a little further forward, about 1/2 ", if I cut down the intake ducts, but that won't give me the distance I need to use the pipe as is.
Anyone else had this issue?
And how in the world would one cut the pipe to shorten it?
Any help much appreciated.

Regards, Jim

Can you take a photo of your pipe and list the measurements?

Another solution is to use a half of bypass section (if you have access to one) see my post #331, my buddy was having the same issue and I gave him a half of bypass section from a Comp ARF Flash...problem solved

Tail Pipe Help.

Jim,

I am in the same boat. I am using a p-80 and the tail pipe is to long. I asked for help on the 13th. If you hear anything let me know.

Thanks
Scott

Scott what is the length of your pipe, how long is your tailcone.

I am using a super eagle in my 2m VJ and my pipe sticks out 1/4 inch past my tailcone.



Alan

For the guys that have flown both the 2m and bigger brother. How does the 2m compare?

They are excellent planes, fly similarly.. a 120 is perfect for the 2m and a 160 for the MKII
The MKII of course is a little larger and easier to see and both planes land like a dream...

I also have the same problem with the tail pipe. I noticed from another thread on RCU that someone had cut the intakes right back which puts the turbine more on the c of g.This then means you have to cut a notch out of both sides if the turbine mount to fit around the ply former which is in the way.(Sounds drastic i know but i checked this out with Ali Machinchy and he confirmed all this was ok to do.Ive also been told the correct distance between the end of the tail cone to the tail pipe (excluding the bellmouth) is 40mm (1.5 inches to you american guys)
Hope this is of some help.
Rich

Well I want to congratulate my friend Cliff, he maidened his 2M Viper tonight.
It flew great from the get go, no adjustments required other than maybe a click or two of aileron. He used my C.G. fixture and set the C.G. to 12.5 mm. See post #314

He is using a Jet Central Falcon for power and it pushed it with authority!
The only issue he has is with the pull pull steering, so now he wants my direct drive version, see post #308.

Oh like I mentioned in post 389 the heating problem is solved
His flight made me want to get back on my Viper Install...

Rich,
I'll post some pics with dimensions this weekend. I need to finish the 'new' motor mounts for the pics to make any sense.

All,
I'd planed on using 1/2 of a heat shield on the top per suggestions on this thread, but I don't believe this would solve the problem of the tail pipe length (unless I'm missing something?).
The JC manual calls for a 20mm gap between the exhaust nozzle and the front lip of the pipe - Not including the bell mount; That's what I'm trying to achieve.
I should know this weekend how far the JC120 will need to go forward to allow the use of this pipe. I don't think it will be possible tomove it far enough.(wouldn't it be ironic to have toactually adjust for a nose heavy CG...Batteries in the tail cone...LOL) As Rich P mentions the forward bulkhead supporting the motor mount beams becomes a limiting factorto the engine mount moving forward.

Aside, kudos to SM for not pre gluing the motor mount beams at the factory. This allow much flexibility for the builder to custom fit the motor mounts for their particular installation.

Thanks for everyone's help, I'll keep you posted on my installation.
Regards, Jim

My tailpipe was the same using P80se but just left it long as it dosn't show with the silver tail cone. Had to trim it in the end as was 1" to long for the car when taking 2 jets! It is a real pain to cut but can be done with a dremal cut off wheel BUT the spacer between the inner and outer pipe will have to be taken off and reinstalled.
Ian.

Tail Pipe Length Issue.

OK here's where I'm at.
I've installed the JC as far forward as the front fuse bulhead will allow the engine mount to go, andthe pipe isa over 1 1/4" too long. This is with the pipe inserted all the wayinto the tail cone (TC) until it's even with the exit end.

[Aside] The SM instruction manual says the pipe should extend past the former a minimum of 10mm. That seems like it may cause the tail cone to get pretty hot. I saw on the thread someone adding BVM Heat Shield to the inside of the TC.But I'm wondering, if thepipe were further inserted past the former a ways further (maybe not to all the way to the end), would this eliminate the TC heat damage possibility?

Here's the pipe with a 20mm gap between the exhaust nozzle and the pipe and the resulting1 1/4" excessive length as measured at the TC.

So I attempted to move the engine further forward by reversing the engine mount (which puts the CG of the engine too far back IMO). The engine mount would then allow the engine to move an additional 1/2" forward. Not enough to solve the problem. Plus the starter cone is now touching the intake center web.The center web has already been cut down as far as I dare, which left 1/4" of material at the glue joint. I don't think I want to cut any further in to it. This also precludes 'notching' the engine mounting bracket to fit around the forward fuse bulkhead as this would still net only a 1/2" (with the engine mount in it's original position) gain due to the intake duct limitation.

Any ideas? It seems like I'm going to either have to shorten the pipe, or buy a new one that fits. Thanks!!
Best regards, Jim

Jim,

Read post 394. The solution is there. That is what I will be doing.

Scott

Is there a reason why you guys are trying to keep the pipe inside the tail cone?
have you thought about the heat damage you are subjecting your tail cone to, why not move your motor back to where it was intended to be installed and have the pipe exit the tail cone by 1/4 inch.




Alan