[gbanger]

You dont have to justify your build time to me Steve, and no your not confusing me, your just a fussy bastard like me who likes to cross all the T's and dot your I's.
The biggest issue with an aircraft like this is that there is no line in the sand build data to work off, and that makes it very time consuming if you want to get it right.
I have been doing the over thinking thing a little with my Jet Teng L39 (which by the way is nearing completion... slowly) but with the Viper I had already done a fair bit research because I was always going to get one, it was just a question of when.
I had always intended running it with a Wemo on 6S and I personally think flaps are a given on a high speed small wing jet because they will stabilise its flight characteristics, help reduced speed flight and help get it back on the ground without to much fuss.
It has a vey high wing loading which simply means... you have to fly it fast to keep control.
Kev knows what I mean the PC9 is a similar aircraft, fly that to slow and it will literally fall out of the sky, the addition of flaperons made a huge difference to landing approach speed and stability.
So I dont think youve been over thinking things Steve, you're just being a methodical builder.
Gazz
PS: But as Kev said "get that bad boy finished".... then I can copy all your good ideas and shit tin the crap ones.

[samste]

Thanks Guys for the Tips

done the wing servos flaps and elevons, elevons ar a issue with the 939 h/k servo as they are width wise about 2mm too big, but with some balsa squashing and servo housing trimming to one side fixed this.

                   

Yes putting in retracts, why ? i don't know.

---

Edit RETRACT FITTING

Ok after all that debating on retracts and i have two different sets, one that is a light set 80gms total and then my heavier set 200gms will not fit in its location as you only have 12mm height clearance, and both my retracts sets length are too long as well.

So will stick too fixed landing gear for maidening of viper and if worthy of Retracts will custom fit a slim set of retracts later.

[wingtipper]

Thanks Guys for the Tips

done the wing servos flaps and elevons, elevons ar a issue with the 939 h/k servo as they are width wise about 2mm too big, but with some balsa squashing and servo housing trimming to one side fixed this.



Yes putting in retracts, why ? i don't know.

---

Edit RETRACT FITTING

Ok after all that debating on retracts and i have two different sets, one that is a light set 80gms total and then my heavier set 200gms will not fit in its location as you only have 12mm height clearance, and both my retracts sets length are too long as well.

So will stick too fixed landing gear for maidening of viper and if worthy of Retracts will custom fit a slim set of retracts later.

thats clever steve . well done

[gbanger]

Hey Steve
Can you do me a big favour and weigh the beastie with batteries, I'm doing some sums and having a better idea of take off weight will be very helpful.
I know you are running 7S, I will be running 6S so the only real difference will be battery weight
Are you using a separate battery and BEC or just the ESC built in BEC
Thanks
Gazz

[samste]

My all up weight RTF Less Lipos will be close to 1750gms

My lipo Weight Has been calculated before i even started so i could position the edf in just the right spot so i can install 6s or 7s by simply sliding the lipos 50mm forward or back to suit in battery compartment position.

Running 6s Setup is an Extra 400gms Total would be 2150gms
Zippy 6s 40c 2650ma lipo

Running 7s Setup is an Extra 800gms Total would be 2550gms
Zippy 3s 20c 4000ma lipo + Zippy 4s 20c 4000ma lipo = 7s 4000ma 20c

Other option is a light 7s Setup is using 3s and 4s 2200ma for testing
Weight would be 467gms

Im using a 2s-8s 200 amp capable Speedy that requires a separate Bec
so i can run 7s as plush only go to 6s

No Doubt without the Lipos this Viper is one heavy sucker and i only fitted fixed landing gear.
Brick Bullet in the Sky That will need flying, not gliding.

Steve

[robair]

G'day All

Just about to start on the air retracts fir the viper.
Manual refers to an air line cutting tool. Anyone know WTF that is?
Cheers
Rob b

[smuzz]

Nope! But please let us know when you find out Rob - I've taken delivery of a set of pneumatic retracts to cut into our PZ Trojan and I haven't got any experience with them at all. Interesting ...

[paulj]

Scissors
That's what Kev and I used anyway.
Really have no idea what it could be.

[~KevJ~]

its probably to get a perfect unpinched cut on the air line to ensure maximum seal on hose barb.. but scissors was the answer i am giving too

[gbanger]

I use a stanley knife which does the trick but I think the cutter they are talking about is like a small pipe cutter similar to what plumbers use.

[robair]

Gday All

Ok I found what one looks like;
http://gravity-werx.com/airlinetubingcutter.aspx

So we are looking at a blade with a hinge!
I think a lightly heated scalpel will do the job just as well.

Paul I would not use scissors, they cut by pinching between the scissor blades. You would get deformation for sure.

As an aside I note that the SAPAC Viper has ventral fins however none to be found in the HK version? This concerns me as they are quite aerodynamically important.

Storms have curtailed work at the moment however all wing servos are now installed (mounted in the wing, not attached to the covers), wing retracts are in, was working on the nosewheel retract install before the storm hit.
I am really enjoying this build!!


Cheers Rob B

[gbanger]

That sounds great Rob,
but here's a tip, take over the dinning room table like I do and banish everyone from said room until work is complete, a bloke can't be working on this aircraft on the back patio....????
Thats not how you make porridge!

[robair]

G'day Gazz

I would use the dining room table however the sniper is on it getting the ailerons re hinged. One if them was seriously out of wack, the other was borderline.
It would be nice to have a "vipernight" with you and Samste at one of out places? I'd really like the ideas that we could get in regards to the set up of the elevators and rudder. This is an area where I am not sure my ideas alone are going to get the best result.
I have previously stated that I don't think one servo is up to speed for the elevators. I want to leave them split, independently driven and possibly mixed slightly to aileron. This is going to leave me with little space to position the rudder servo. I am thinking of mounting the rud servo up the back of the fuse in some space under the tail fin. The control run will be nice and short and will be all clear of the duct tubing. How have you and Steve hooked up your surfaces?

Cheers
Rob B

[gbanger]

Mine is still having a little rest in the box it arriverd in.
I pulled it out for a preliminary inspection and personal think tank but after that I put it away.
I am working on a new build ethic which goes a little like this:-
FINISH ONE FRIGIN PROJECT AT A TIME (2 at the most.....maybe)
that way my brain won't explode... so to cut to the chase
1. Finish build on Jet Teng L39 - completion date... mid January
2. Finish Skyfun Twin Rig - completion date ... mid February
3. Carry out squadron power upgrade - every motor and ESC take one step to the right - completion date ... mid March
4. Commence building Viper - completion date ... hopefully before April 30
So you can see that the Viper is a LONG way off at this stage...
However ... due to my spontaneous inability to stick to game plans it could be on the table as soon as .....
Gazz

[robair]

G'day Steve

Would you be able to do me a favour and measure the height off the control surface the top hole of your viper control horns are?
The horns were missing from my kit so need to source alternatives.
My build is now very close to complete.
However, nose wheel is doing my head in big time!
Also, would you and Gazz like to join me and order the ventral fin bits from Sapac, aside from looking cool I think they will greatly assist flying characteristics.

Cheers
Rob B

[kizza42]

Rob, I made mine for my Hotliner, Shaped one horn out of a plate of carbon fibre then sanded 3 others to suit, one drill hole and done! Took 30 mins

[robair]

G'day KV

Yeh that is an option, I could easily make horns out of pcb or carbon strip.
However I want my horns screwed through the wing not epoxied.
I really want to know what Sapac supply as standard so I can refer to that and fit screw through horns.
Having said that if epoxied in horns survive on your hotliner they will be fine in the viper. May rethink re screwed in horns!
The recommended height of the top hole of the horn is my critical unknown right now. That dimension could be similar to your hotliner horns?

Cheers
Rob b

[samste]

G'day Steve

Would you be able to do me a favour and measure the height off the control surface the top hole of your viper control horns are?
The horns were missing from my kit so need to source alternatives.
My build is now very close to complete.
However, nose wheel is doing my head in big time!
Also, would you and Gazz like to join me and order the ventral fin bits from Sapac, aside from looking cool I think they will greatly assist flying characteristics.

Cheers
Rob B

My Control Horns is 8mm off the control surface to top hole, but i guess it would also depend on what servos you use to actual height as a wing mount servo would be different as i used standard mg 929 servos and compressed the balsa slightly to fit snug and level which i guess is not the right thing to do but it worked.

[robair]

G'day Steve

Thanks for that, I am using mg939's too however mine are mounted in the wing not on the covers like yours.
If work doesn't get in the way I hope to finish the viper today.
Tests last night indicated she balances perfectly with a 6s 40000mah batt. Swweeeet. Glad I don't have to worry about that.

Cheers
Rob B

[gbanger]

What EDF and Motor are you running in yours Rob?
I have looked at a few options but have not made my mind up yet!

[robair]

G'day Gazz

Stock 70mm Sapac fan mate, full power runups give a healthy amount of thrust however feel that this fan will only give "sport" performance. The way the weight is piling on suspect an angrier fan may be more appropriate. Will only really know after maiden.
As Steve stated earlier she will be a brick if speed is not maintained, a better power to weight ratio will help if you get her on the wrong side of the lift/drag curve, I don't think the Sapac fan will have the mumbo to push her out of that condition

Cheers
Rob B
Cheers
Rob

[gbanger]

Well hello Vipernauts its time to get the lead out and get these beasties airborne.
After an absolute shitload of maybe this and maybe that, I finally got around to ordering all the goodies for my Viper, and surprise, surprise... they all turned up today... so without any further ado, I have my Viper on the table and hope to have it in the sky by the end of April. (Yeh right)

I am running this fan unit
http://www.hobbyking.com/hobbyking/store...duct=27559

I am running these servos
http://www.hobbyking.com/hobbyking/store...duct=23340

I am running this ESC
http://www.hobbyking.com/hobbyking/store...oduct=9328

I wont make the battery decision until I do my final C of G checks when the aircraft is complete, but I think a 6S 3500 40C or there abouts will be close to the money.

It looks like a pretty good package on paper, the aim of this project is to build a high quality inexpensive composite jet that has reliable, predictable flight characteristics that goes like a shot dog... and is most importantly EASY & FUN to fly... time will tell.
I am setting mine up for bungy launch only, that way I don't bleed unnecessary energy draging my arse into the sky, not to mention pulling thrust depleating useless shit like landing gear/retracts all over the stratosphere.
As it is a low wing aircraft and I will be landing on my belly I will be setting up all my control linkages on top of the wings, that way I can keep landing impact stresses and damage to a minimum, but I will sort that out as the build progresses... exciting isn't it!!!
GO VERTICAL OR GO HOME !!!

[samste]

lol

mines in the roof and about 80% built, got stuck at where to mount elevator servos as my build i want to mount them on tail adjacent elevator, to reduce bending and stress of rod to elevator

[samste]

Ok I'm Inspired Now By Andrews YouTube Viper Jet Clip and Awsome Sound.

My Existing 70mm edf on 7s was a hot setup and noisy, so Change of Tactics to Give it Power, Nice Sound.
Same setup on My Stryker Edf, which is Proven to Go well and sound well.

So I Have got out of the Roof The Viper and ripped the Guts Out (the old 70mm edf and electronics) and Glued In a 90mm, Yes 90mm edf Changesun in 70mm viper Jet.
Checked COG where the edf is Glued in and its pretty good.

Once That Dries i will fit Electronics and servos for elevator, rudder.
This Setup will be a lot lighter Than Original which is what i want, as i read that the viper jet setups people are running are heavy and changes flying Characteristics Dramatically.

Lol, All of you other Viper Heads need to get Started as well

           

[kizza42]

Bonkers!!! I love it!

[brotherblonde]

Thanks Steve....I mean sorry...I mean, wow that thing is going to scream. In a nice way.

[secant0give]

I must confess to having something similar still sitting in a box in my shed it may be a little while before it gets to the front of the cue tho'

[gbanger]

Mine is like a HK back order. Its coming....
Iv'e got everthing I need to complete it... I just need to find the time.
Throw those bloody retracts/landing gear in the bin Steve... that's how I am keeping the weight down in mine... that is why they invented bungee's.
My powerplant is not quite as impressive.

HK DPS 2200kv 10 blade 1900w on 6S with 2.5kgs thrust.
       

[samste]

Gazz That still should be sweet with That setup.
Good ESC I see, Thats what I'm Using as well and am using in Stryker edf setup as well.

I got Fixed Gear Installed with steerable fixed nose wheel, a little drag to keep it in line but still light weight.
Didn't feel the need for Retracts and the added weight either, but still wanted to be able to take off from ground.

Steve

[samste]

OK,

I spent 2 hours mucking around with twin rods to back elevator surfaces and heavy duty servo at front to push and pull elevator control.
Well i came to a realization that it great pulling the rod and the control surfaces move well and 100% but when pushing to make elevator go up its about 50% and servo works Hard.

Not Happy with the Outcome i decided to mount individual servos at rear adjacent to each elevator side.

(Have Read somewhere that this Push Rod Setup was an issue and many peoples servos failed in Flight due to the hard workings required by servo)

Will Update with Pics when i do the Workaround During The week, as i hoping to get it Airworthy soon.

Edit Finished Workaround, Rudder to do now.

   

Steve