Vettster

This is not an 8' long Skymaster Viper jet here. When you are talking small jets like this.. Every one of them is sensitive to CG. The Wrong CG in the manual was 128mm The correct CG is 98mm We're talking about 30mm here. Im not going to bother with the math..But if that were scaled up to the Skymaster Viper I would bet it would be an incorrect CG of about 6" I DO think that would have a very negative effect on a large jet, as I have already seen many vids of the Skymaster Viper crashing because of the Wrong CG being posted.

Mine lasted more than one flight, and so did Hundreds of others once I found the sweet spot. Did ProDesign Change the instructions? NO! Did HK do anything to help? YES! They posted the instruction on their site with a WARNING that the CG should be set at 98mm

Bob_B

My Feedback: (11)

just kidding with you p.

icepilot

I flew this Viper with the Wren 44, turned out the stabs were too small, Skymaster redesigned and replaced them, now it flies great!
Look at the quite scary takeoff, also it had a nose-down stance which has been corrected.

[youtube]http://www.youtube.com/watch?v=XKF8zw7iq98[/youtube]

eazyp

My Feedback: (35)

Well wasnt feeling so vicurious today and headed out to one of my local flying fields,was a nice day so I decided i was going to re-maiden the viper,It was a absolute SUCESS!!!! made a couple adjustments since my last post. First thing I did was to change the incedence (AOA) by getting the nose gear up,second was to revisit the C.G. special thanks to Vettster his C.G. was Key to my success, I was to nose heavy,reading the build threads on this plane I came up with a cg of 85-95mm and ofcourse I would start out at 85mm, he suggeted a balance point of 98-100mm upside down,i knew he had to be right,because i do remeber him being the first one to get this plane to fly correctly. this led me to remove 3oz. of lead out the nose. then I decided to go with half flap for take off and only 3/4 the fuel load,also turn the tubine all the way up to max rpm, so I was nervous because I didnt know what to exspect, lined up and gave her full throttle,she was off down the run way at about 300 ft or so ,a little pull back on the stick she rotated wings level, you should of seen the smile on my face. like I said in the last flight report she was true and tracted strait as an arrow once she was flying, landing with full flap was easy as pie. SO now I will have to spend some money and get a hold of tam@ Tamjets and get the plane a proper set of landing gear,and watch out for the new pait job. will get video this spring as flying season is pretty much done here,not to mention the hk retracts wont hold up much longer. Thanks To ALL the guys who left someting positive for me to correct the problem. She's A KEEPER. Paul

Bob_B

My Feedback: (11)

Way to go p. Glad to hear you sorted it out. Ill be building my jtm Viper with 44 soon.

eazyp

My Feedback: (35)

Thanks BOb,and good luck with your viper,I would also like to thanks Kevin for doing the first maiden flight for me.

Dr Honda

My Feedback: (4)

Glad to hear it worked out, and congrats!!

I know when I strapped a Wren 44 into a CMP T-45... I wasn't sure either. (Seen a bunch crash for the same reasons) So... I talked to all the guys who made them fly well on EDF... and then I let a pro do the maiden and trim-out flight.

Vettster

Good Stuff! easyp. Glad it worked out for you

kevin

My Feedback: (2)

no problem, sounds like its all sorted out now. we figured it was nose heavy by how diffucult it was to lift the nose even after the maiden. good luck...