ExtremeJets/Skymaster Viperjet 2M tailpipe question.
11-04-2016, 04:55 AM
#1
ExtremeJets/Skymaster Viperjet 2M tailpipe question.
i'm getting ready to start an Extreme jets Viperjet 2M and i have a pipe question... I just picked up a Jetcat p140 RX for the viper. i know it's a lot of power but i plan on turning it down . i want to know if the STOCK pipe that comes with the kit is ok to use with the 140.. i posted the question in a different forum and only got one answer and i'd like to a second opinion or a general consensus on it. i see alot of guys running 80's and 100's . any structural issues with the bigger turbines? thank you ,WB_1
11-04-2016, 05:41 AM
#2
Works fine with my Cheetah SP ( 140, 32lbs ) No issues. However I did put BVM heat shield in the tailcone and I think I painted heat shield up in the spine of the rear section... I would recommended that for any size engine.No engine hatch on top keeps it kind of warm in there on the ground. No structure issues that I found. I did however put a full size servo in the fin for rudder. The mounting plate in there is sized for the midsize servo like is used on the elevators. I wanted more servo for the rudder because it's a big rudder/fin. Wasn't convinced the smaller servo would do the job for knifedges and such. Also keep in mind the recommendation in the manual of max airrspeed of 180mph. Never have seen issues with that myself or with others, but it's in the book. I don't fly that hard myself anyway, but it would be easy to do with the 140... 
Dan
Dan
Last edited by rcjetsaok; 11-04-2016 at 05:48 AM.
11-04-2016, 05:58 AM
#3
Works fine with my Cheetah SP ( 140, 32lbs ) No issues. However I did put BVM heat shield in the tailcone and I think I painted heat shield up in the spine of the rear section... I would recommended that for any size engine.No engine hatch on top keeps it kind of warm in there on the ground. No structure issues that I found. I did however put a full size servo in the fin for rudder. The mounting plate in there is sized for the midsize servo like is used on the elevators. I wanted more servo for the rudder because it's a big rudder/fin. Wasn't convinced the smaller servo would do the job for knifedges and such. Also keep in mind the recommendation in the manual of max airrspeed of 180mph. Never have seen issues with that myself or with others, but it's in the book. I don't fly that hard myself anyway, but it would be easy to do with the 140...
Dan
Dan
11-04-2016, 06:51 AM
#4
Weight may be something to think about. The 140 is a lot heavier than the 100 or 80. I put a 140 in a Sprint and dialed it down. But the vertical suffered. So I turned it back up. Then, the stab blew apart cause I was pushing it too hard on a transition from horizontal to vertical. For me, it was kind of hard to tell where the right mix of power would be to get the vertical back w/o blowing the plane apart. I went back to the 100 for the replacement plane.
11-04-2016, 07:15 AM
#5
Weight may be something to think about. The 140 is a lot heavier than the 100 or 80. I put a 140 in a Sprint and dialed it down. But the vertical suffered. So I turned it back up. Then, the stab blew apart cause I was pushing it too hard on a transition from horizontal to vertical. For me, it was kind of hard to tell where the right mix of power would be to get the vertical back w/o blowing the plane apart. I went back to the 100 for the replacement plane.
Last edited by warbird_1; 11-04-2016 at 07:18 AM.
11-05-2016, 08:50 AM
#9
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Ron,
I'd be more concerned about the high residual thrust of the 140 for landing ease. You can turn down the top end but the idle thrust. remains the same. You may be OK with the Viper if the flaps slow the model enough for landing. Try it and see. Good luck with your new bird.
Rgds,
Art ARRO
I'd be more concerned about the high residual thrust of the 140 for landing ease. You can turn down the top end but the idle thrust. remains the same. You may be OK with the Viper if the flaps slow the model enough for landing. Try it and see. Good luck with your new bird.
Rgds,
Art ARRO
11-05-2016, 01:24 PM
#11
Warbird 1
I have a 2M Skymaster viper with a Merlin 140 in it. Don't turn the thrust down as you never know when you need it. Just remember that you have to be a participant not an observer on the left stick. The verticals are just about unlimited especially toward the end of the flight. The Merlin is a bit lighter than the Jetcat but keep everything as far forward as you can and I only had to add a few ounces in the nose. I fly most of the flight about 2/3-3/4 power. No problem landing with the idle thrust of this 140. The more flap you can get the better. Once it lands it sticks to the ground. Its a great flyer, just wish Skymaster did a bit more thought about putting it together.
Jack
I have a 2M Skymaster viper with a Merlin 140 in it. Don't turn the thrust down as you never know when you need it. Just remember that you have to be a participant not an observer on the left stick. The verticals are just about unlimited especially toward the end of the flight. The Merlin is a bit lighter than the Jetcat but keep everything as far forward as you can and I only had to add a few ounces in the nose. I fly most of the flight about 2/3-3/4 power. No problem landing with the idle thrust of this 140. The more flap you can get the better. Once it lands it sticks to the ground. Its a great flyer, just wish Skymaster did a bit more thought about putting it together.
Jack
11-06-2016, 02:39 AM
#12
Warbird 1
I have a 2M Skymaster viper with a Merlin 140 in it. Don't turn the thrust down as you never know when you need it. Just remember that you have to be a participant not an observer on the left stick. The verticals are just about unlimited especially toward the end of the flight. The Merlin is a bit lighter than the Jetcat but keep everything as far forward as you can and I only had to add a few ounces in the nose. I fly most of the flight about 2/3-3/4 power. No problem landing with the idle thrust of this 140. The more flap you can get the better. Once it lands it sticks to the ground. Its a great flyer, just wish Skymaster did a bit more thought about putting it together.
Jack
I have a 2M Skymaster viper with a Merlin 140 in it. Don't turn the thrust down as you never know when you need it. Just remember that you have to be a participant not an observer on the left stick. The verticals are just about unlimited especially toward the end of the flight. The Merlin is a bit lighter than the Jetcat but keep everything as far forward as you can and I only had to add a few ounces in the nose. I fly most of the flight about 2/3-3/4 power. No problem landing with the idle thrust of this 140. The more flap you can get the better. Once it lands it sticks to the ground. Its a great flyer, just wish Skymaster did a bit more thought about putting it together.
Jack
11-06-2016, 02:51 AM
#13
Ron,
I'd be more concerned about the high residual thrust of the 140 for landing ease. You can turn down the top end but the idle thrust. remains the same. You may be OK with the Viper if the flaps slow the model enough for landing. Try it and see. Good luck with your new bird.
Rgds,
Art ARRO
I'd be more concerned about the high residual thrust of the 140 for landing ease. You can turn down the top end but the idle thrust. remains the same. You may be OK with the Viper if the flaps slow the model enough for landing. Try it and see. Good luck with your new bird.
Rgds,
Art ARRO
02-12-2017, 02:58 PM
#16
Jet Cat had/has a table for pipe sizes and gaps between the pipe and exhaust cone. I was not able to find it. But is was posted on RCU a couple months ago in this forum.
Sitting here waiting myself for some "Heat Shield" to come in the mail for my new Ultra Flash. Old can was hard as a rock when I opened it last Friday. With no outside pipe for half the distance to the tail cone, it looks a bit risky w/o Heat Shield. I saw an Ultra Flash burn up the fuse at Monroe a while back. A bit to much propane and paint was smoking in seconds. Then came the flames.
On a side note: On the Sprint's Stab: The bolts that held on the stab ripped out thru the Stab. The stab was the biggest piece I found and it was the closest. The debris field was about 200' long. Not much left to look at. Nothing was reusable.
Sitting here waiting myself for some "Heat Shield" to come in the mail for my new Ultra Flash. Old can was hard as a rock when I opened it last Friday. With no outside pipe for half the distance to the tail cone, it looks a bit risky w/o Heat Shield. I saw an Ultra Flash burn up the fuse at Monroe a while back. A bit to much propane and paint was smoking in seconds. Then came the flames.
On a side note: On the Sprint's Stab: The bolts that held on the stab ripped out thru the Stab. The stab was the biggest piece I found and it was the closest. The debris field was about 200' long. Not much left to look at. Nothing was reusable.
03-21-2017, 11:46 AM
#17
so i'm into the build of the viperjet and i started to do the pipe/turbine setup and i ran into something strange. the bellmouth on the pipe is so big i can't move my engine forward and get rid of the excess pipe sticking out the back because the bellmouth hits on the engine mount . i thought about relieving the inside of the engine rails enough to slide the pipe forward . I'm not impressed with the lack of instructions .which shows a totally different bellmouth and mount system. anyone else run into that same situation?
03-21-2017, 12:07 PM
#19
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And you can do cooling vents in the tail, I did in mini and it really helps with the heat.
http://www.rcuniverse.com/forum/rc-j...s-tips-13.html
http://www.rcuniverse.com/forum/rc-j...s-tips-13.html
03-22-2017, 03:13 AM
#21
And you can do cooling vents in the tail, I did in mini and it really helps with the heat.
http://www.rcuniverse.com/forum/rc-j...s-tips-13.html
http://www.rcuniverse.com/forum/rc-j...s-tips-13.html
03-30-2017, 11:31 AM
#23
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http://www.rcuniverse.com/forum/atta...3&d=1375572293
I have no heating problem
03-30-2017, 01:15 PM
#24
fly, i looked at that but don't see the advantage of them being on the bottom. not to mention the work involved . i thought by having them in the back the heat at the top of the fuse would be removed better being higher up and at the back.here's two thoughts that i had
