mikedenilin

My Feedback: (67)

Now you need 11 Channels if you want to use a gyro. .

Gyro is is not necessary for this jet to fly great, but it will make you look like a pro. You can easily do 4 point role or knife edge 2000 feet along the edge of runway in a near perfect straight line. The 3 axle gyro just makes this jet fly solid in any bad wind conditions. Sometimes it's too easy and I feel my real flying skills deteriorate over time. Maybe I am getting older.

I flipped my Viper on the runway last year at Tucson Jet while attempting a 20mph cross wind landing. I think the gyro would had saved it should I had added one. I will be there again this year. See you then.

Mike

VF84sluggo

My Feedback: (55)

No kiddin', Gus. When I posed the question, I was looking for informative input, not worthless wise-cracks.

Sluggo

essyou35

My Feedback: (11)

It wasnt meant that way, I mean it is very easy to fly and no need to overthink it. Geez sensitive around here! The flat tire thing is an inside joke about someone who did wuss out.


Just keep it simple there is nothing to worry about. That doesnt give you the information on a gyro but I am saying its not needed based on my limited experience so far.

cosmo21

I could see this as a giggle, you are correct. It's an easy Jet to fly, really doesn't need electronic intervention. To me that is just another potential failure point.Keep it simple and enjoy. I know you will enjoy, it's a fine jet.

If ya want to use gyro's ect, fill ya boots. Gadjets are fun.

MH

mtnflyer14

I appreciate ALL the inputs on the gyro issue. I do have thick skin, no harm, no foul. After reading everyone's observations on the Viper flying qualities, it seems to me that the jet flies great without a gyro, but in winds/crossswinds, the gyro is helpful. Comes down to pilot preference; imagine that. Mike, looking forward to seeing you in Tucson.
Regards,
Gus

quist

My Feedback: (198)

I test flew one of these Vipers for a buddy last Saturday. It was equipped with a p100rx. It was a fantastic flying jet. All it needed was a few clicks of up trim.

mtnflyer14

That is good to hear, Tony. That seems to be everyone's opinion that I have talked to lately. Mine should be ready by the end of the week. Putting a K-80 in it since I had one available, which should be fine here; might need more back in Colorado. Are you going to Tucson?
Regards,
Gus

essyou35

My Feedback: (11)

Gus a K80 will be fine. While I have been using a K100, I have done entire flights less than 1/2 throttle.

This is one of those jets where this is not a huge speed increase between 3/4 and full throttle. Its pretty draggy with the big intakes and thick wings, but it also flies around like a trainer because of that.
Keep in mind though it will snap/tip stall, and it will do so before the F-86D will, and it is just as nasty too.

I should of bought this jet in the first place, its a much better trainer adn way easier to build!

mtnflyer14

SU35, thanks, yes I think it will be fine. I watched the Viper here at Desert Jet Storm in Phoenix on a k-100 and everything except starting verticals was done a half or just slightly over. I got the tanks out yesterday and pressure checked them, so hope to have the fuel system including pump, filter, solenoids, etc., done today.
Regards,
Gus

VF84sluggo

My Feedback: (55)

Here are some pics of my Viper. Zero Fuel Weight (full UAT) is 24.1 lbs.

So, full-fuel weight is just short of 30 lbs (using a nominal 7.1 lbs/gal for diesel.) Based on Kingtech's published 22 lbs of thrust (standard day) for the K100G, that gives a thrust-to-weight of .73 at max gross weight, .81 at half-gas...not too shabby!

mtnflyer14

Randy,
Great looking jet and very clean install of all the 'stuff'. Being a Kansas Jayhawk fan, there are a few too many 'Gator decals adorning the airframe, but other than that - awesome paint scheme!
Regards,
Gus

Jeremy_D

Looks Great.

Also add some crow for full flap, you can really slow it down!! Never had it snap or spin either, it really is a great jet to fly

VF84sluggo

My Feedback: (55)

Thanks gents!

LOL, Gus, if the Gators don't start playing better, I may paint it up in Jayhawk colors!

Jeremy, funny you mention crow. As I was taking these pics today, I also decided to setup some crow via the left slider, like I have on my Boomer. Gotta admit, I wasn't sure if I should do it, but you say it works ok and would recommend it?

Jeremy_D

Definitely,

I think there is a PDF in this thread with my setting I used that we supply via GJC. I used about 4mm from memory. I know it's been discussed in here a few pages back but it really helps with the slow speed handling on landings.

Cheers

Jeremy

VF84sluggo

My Feedback: (55)

Ok good. I'll search for the file, and set up accordingly. I wasn't sure what the max deflection should be, and I might have to dial it back a little.

Sluggo

essyou35

My Feedback: (11)

Just to compare, My wet weight is 27.5 lbs with 90oz of fuel on board. I am using two 2s 3300mah 40C lipos for the RX and a large 3700mah 3s Life for the turbine. I have maybe 1/2 lb of weight in the nose.

I am re configuring mine now I expect to lose about 1lb using much smaller lipos.

I also use crow helps it keep from snapping.

VF84sluggo

My Feedback: (55)

Yeah, my jets never seem to be as light as others'. Can't explain it so I just expect it and get over it. I wish they did, though, because as we all know, lighter is better (as one of my Aero Eng profs once said, anyone can build an airplane strong enough, the trick is to build it just strong enough.)

I am rethinking the smoke tank/fuel tank arrangement. I don't have any dead weight in the nose right now (and I'd rather not, as it seems my Viper is on the porky side already), and the cg is as far aft as I'm comfortable with right now. I've seen the posts about putting fuel tanks in the smoke tank location, burning from them first, then from the forward main tank. I like the the way the cg is affected by this, with a burn into a more forward cg initially. But, I'm not crazy about the added fuel system complexity.

I am concerned about the possibility of ending up with an aft cg that could be problematic if the smoke tanks remain full (i.e. a pump failure) and the main is burned down. Now, one course of action to prevent this would be to land right away (but heavy) if carrying smoke and smoke system failure is noticed. I have not yet done a cg check with the smoke tanks full, empty fuel (full UAT of course). I will do that today.

So, as I consider if I want/need to re-plumb things, anyone know the capacity of the smoke tanks? I don't see where I'd fit two 24oz DuBro's back there in the stock smoke tank locations.

Sluggo

mtnflyer14

Sluggo,
I have the GJC smoke system for the Viper but I don't see any volume stamped on the tanks. I talked to Jose about the smoke; he has it set up per the GJC layout - two stock fuel tanks in front of CG, the two smoke tanks further aft. He said he forgot to open the valve for the smoke system one flight and ended up landing with full smoke and noticed no big CG issues.
Regards,
Gus

mr_matt

My Feedback: (10)

As a heads up I saw a guy blow a wing panel off of one of these Jet Legend vipers last weekend. If broke just outside of the tubular spar, and we could see that the plywood spars are slotted for the ribs so all 5 of them snapped clean. Of course the plane looked overpowered but I don't suspect this was a build flaw, just a limit of the design. The glueing and all of the workmanship actually looked top notch.

mtnflyer14

Sluggo,
I just finished reading all 37 pages to see if I missed anything on my build and stumbled on to the smoke tank volume - 31.6 ounces in each smoke tank.
Regards,
Gus

wildnloose

That is one good looking jet, love the color, should be easy to see. I just might have to bite. Do you mind if I get one with the same color scheme (well I may switch the blue out for purple)?

Currently saving my pennies to get one of these (maybe power with Wren 100).

VF84sluggo

My Feedback: (55)

Thanks for the tank capacity info, Gus.

I did notice an aft shift of the cg when I re-checked it with the smoke tanks full. My Viper did not come with any cg markings pre-marked anywhere, so I've had to go by what I've read here. I've seen a few different cg locations mentioned: 35mm aft of spar tube center, and 40mm aft of spar tube center. With full smoke tanks, I'm at the 35mm location, or maybe just a tad less (forward) of this.

Sluggo

mtnflyer14

From what I have read, I think you are good to go at that CG location. 35-40 mm aft of the center of the wing tube is supposedly very comfortable. Mine had a CG marked about 20 mm or so aft of the wing tube, but sounds like folks are going more aft than that.
Regards,
Gus

VF84sluggo

My Feedback: (55)

Ok, good. I couldn't remember what the stock number was, and since I had no factory mark, I'd set my cg up just aft of the spar tube...heck, probably not even as far as 20mm.

Thanks for the info, Gus. With this, I'll just stick with the standard set up as far as tanks go, and keep smoke oil and fuel as-is. No need to go to the trouble of totally re-working the fuel and smoke systems.

Sluggo

HiCurrent

I've just maiden flight my viper last weekend. With the cg is about 20mm behind the end of the wing tube the CG still feel nose heavy. At about in the middle of the flight, I did a half Cuban 8 and on the last 1/4 of the loop, it snapped roll on me. But luckily it came out after I release the stick. It acted exactly the same as one of the youtube video of this plane http://www.youtube.com/watch?v=LZpv0O1ubMs. You can search for the thread here on RCU on Jet legend viper unexplained crash.
I think the nose was still heavy resulting me to use too much elevator. I've move the CG back further and will test it again this weekend. Also, I noticed that in the air, the plane has a humming noise (more than a mid frequency whistle). I don't know if the hum is from the holes and opening on the plane or it is came from fluttering. It didn't sound like flutter that I know of. I checked the paint on the control horns of both ailerons and rudder but didn't see any paint chip, so I don't think it was flutter. Because I use metal clevis on both ailerons and rudder, that's why I have a small play. I recalled that Barry from Kingtech has a comp arf plane that sound exactly the same in the air. Have anyone notice this humming from their viper ?