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Old Dec 03, 2012, 01:55 AM
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The_RattleSnake's Avatar
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Quote:
Originally Posted by setxws6 View Post
We need details on what you did to get that extra mph
I wanna get the doppler conformation before I brag to much :P
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Old Dec 04, 2012, 04:20 PM
ZX-10R pilot
setxws6's Avatar
USA, TX, Lumberton
Joined Oct 2005
383 Posts
Been slow to getting my latest Radjet project moving along, but made some note worthy progress. I decided that instead of sawing off the wing tanks, I'd rather sand them down to increase my wing area by a small margin...
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Old Dec 06, 2012, 12:48 AM
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760 Posts
Almost how I did it too.

I cut the ends on a 45 deg angle to act similar as winglets.
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Old Dec 07, 2012, 03:17 PM
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UK
Joined Jul 2008
391 Posts
2700 kV

Flew pretty well as stock - and agree 100% that the COG needs to be moved back, mine ended up at the front of the rather small and useless finger grips. Soon got bored and felt the need 4 speed, so heres my mods - unflown as yet due to weather here in Blighty, but expecting a right little rocket on this set up.

1) Turnigy 2700 kV outunner on new ply mount.
2) 60A plush ESC
3) APC 6 X 5.5

Tried this motor on 4s, but even with a 4.5 X 4.5 graupner speed prop, the current was way too high, at over 60A ( 50 burst peak on this motor ), so settled on a larger prop with 3s.
( helps keep the weight down too - AUW now just over 1lb ).
Wattmeter readings are 50A and just about 500 Watt, as the 3s 1800 packs are obviously under quite a load so the voltage drops a bit.
Heres a few pictures....I deliberately remounted the motor as the stock ply rings looked way dodgy, and I wanted it hanging off the T/E a bit to help the COG. Also got the ESC a good way back, and cut away foam to keep cool.
I had already flown her stock, so had to add the 8mm carbon tube spar retrofit, glued with gorilla glue and then CW tape over, then some trim strips to hide most of it.
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Old Dec 08, 2012, 05:35 AM
ZX-10R pilot
setxws6's Avatar
USA, TX, Lumberton
Joined Oct 2005
383 Posts
Looks good badger, should be a rocket with 500watts. Even with 350 watts its almost unlimited vertical. So you should have unlimited vertical and probably around 100mph speeds.
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Old Dec 08, 2012, 11:26 AM
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UK
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Originally Posted by setxws6 View Post
looks good badger, should be a rocket with 500watts. Even with 350 watts its almost unlimited vertical. So you should have unlimited vertical and probably around 100mph speeds.
:d:d:d
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Old Dec 16, 2012, 11:14 AM
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Kurt's Avatar
United States, TX, Houston
Joined Sep 2003
1,868 Posts
well the first flight of the Dual Radjet was not the success I planned on....

I'd been racking my little brain about how to get her in the air for the maiden. There's no good place to grab her near the CG on the central wing and I'm not confident enough in "boomerang" tossing her by a wing tip or an underhand "horseshoe" throw by grabbing the leading edge of the center.
Then a lightbulb went on and I thought "Oh! A dolly would be cool! Just like the ME63 rocket planes!".

Had some struts and big tires from the P-51 I put upgraded gear on, a nosewheel from a dead T-28 and bunch of basswood so fabbed one up. Got it rolling dead straight on taxi runs in my driveway and went to the field a couple weeks ago on a calm, sunny day. There was a bit of concern about the props clearing the dolly but I thought as long as she got in the air quick enough they'd clear. If only I thought about that a little more...

With about 6 people watching at the end of the day took her to the runway and made a few medium speed taxi tests to make sure she'd stay on the runway.
Finally set her up, ran up the throttles to ~60% and whoa! she shoots aways (they'll be no problem with power that's for sure!), then about 20' after rolling BAM! in an explosion of plastic props, some foam and wood she's suddenly sliding along the runway on her belly with the destroyed dolly spread around the tarmac.

Sure enough, as soon as she started to lift her wings cleared the little tabs, the dolly slowed and the 20000+rpm props hit the dolly's rear crossmember.
The #2 engine mount broke away and the broken prop gouged a few nice scars in the top of the foam airframe and tore up the foam behind and around the mount pretty good.

Re-glued the motor mount, patched up the scars and replaced both props so the plane is once again ready for flight.

The dolly broke apart at the joints; after toying with the idea of laying down the rear wheel structure 90 degrees to be much closer to the ground decided to glue her back together just as before, except with extended vertical "wing holders" so that now the plane will drag the dolly along until it's high enough that the props will comfortably clear the structure.

I used thin balsa for the longer tabs so in case one or both props hit them as she's going up they should break instead of the props.

The good news is she wants to fly. After I get her trimmed out I have no doubt that she'll take right off from my hand, vertically if desired.
Time wise we should be well past nice flying weather in Milwaukee but it still hasn't snowed here and temps are regularly in the high 40s. If there's a nice day this week may be able to try again soon.
wish me luck!
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Old Dec 16, 2012, 12:17 PM
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tracknoob's Avatar
South Florida
Joined Dec 2010
5,051 Posts
Terrific attempts, and great looking aircraft. Looks like you almost have it licked now!
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Old Dec 16, 2012, 06:53 PM
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Kurt's Avatar
United States, TX, Houston
Joined Sep 2003
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Thanks, I hope so!!!

BTW I have video of the first "launch" attempt.
Will splice it in with the eventual successful flights
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Old Dec 17, 2012, 06:46 AM
ZX-10R pilot
setxws6's Avatar
USA, TX, Lumberton
Joined Oct 2005
383 Posts
Maybe you could glue in some sort of foam, balsa, or ply tab in the middle on the cg. Something you could grab to handlaunch it.
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Old Dec 17, 2012, 07:21 AM
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United States, TX, Keller
Joined Jul 2011
2,660 Posts
Kurt,

Where do you guys fly in MKE ? I'm headed up that way for the holidays.

-Hawk
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Old Dec 17, 2012, 07:52 AM
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Kurt's Avatar
United States, TX, Houston
Joined Sep 2003
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Quote:
Originally Posted by setxws6 View Post
Maybe you could glue in some sort of foam, balsa, or ply tab in the middle on the cg. Something you could grab to handlaunch it.
I did install a "large" Dubro skid right in front of the central elevator servo about at the CG but it's only big enough to pinch between the thumb and index finger. Until I know the CG is correct I'm not confident enough in my left-handed throwing to launch this way, but after she has at least one good flight (trimmed for roll and CG at least very close) I'll try it this way.

Quote:
Originally Posted by dahawk47 View Post
Kurt,

Where do you guys fly in MKE ? I'm headed up that way for the holidays.

-Hawk
hey Hawk -
Bong Recreational Park's RC field is my favorite. It's about 30 minutes south of Milwaukee:
https://maps.google.com/maps?q=Bong+...onsin&t=m&z=10

Here are some pics:
http://www.rcgroups.com/forums/showp...postcount=5070

This time of year isn't the best there however, they allow pheasant hunting until 2PM (may be over now?) and by that time the sun is low and right over the runway. From ~March-September it's really great though.

There are a couple parks ad Schools in Milwaukee where I fly my smaller planes but the big P-51, Stinger EDF and the Dually Radjet are really too much for them IMO.
If you bring your planes or just want to meet up if there's a nice flying day shoot me a PM!
Me and a couple other RCGroupers sometimes meet at Konkle Park which about 5 minutes from my house:
https://maps.google.com/maps?q=Konke...m&z=13&iwloc=A

Only downside this time of year is the goose poop. I'm getting good at catching my Wing Wing mid-air instead of belly landing
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Old Dec 17, 2012, 11:59 AM
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Joined Mar 2006
463 Posts
I hope it will work out for you, but I feel the "tugging" of the vertical tabs along the leading edge could give you some real weird pitching moments!

Maybe safer to change the design of the dolly a bit. in stead of running a trike with a high placed central longitudinal beam, you could make it into a 4 wheeled buggy. It can be run with fixed front and rear axles, (low to the ground) and the rods where the wings are resting on are angled pieces which are part of the side of the dolly, the only piece that is built higher, so even while at rest the props clear the ground AND the dolly axles. To make it even better you could omit the whole rear axle and leave both rear wheels independent, that gives you an even beeter prop clearance (only need to clear the ground now, so the whole thing can be lower). (The chassis of the vehicle is then U shaped, with the opening to the back of the direction of takeoff.

If you feel you need to stay with a trike design, you could construct the central logitudinal beam low, (at the height of the front wheel axle). Then built up framework with clearance in the middle. (as in the buggy design)

Good luck!
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Old Dec 17, 2012, 12:54 PM
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Kurt's Avatar
United States, TX, Houston
Joined Sep 2003
1,868 Posts
Good ideas Martin!

The main reason I went with a trike was to allow easy steering adjustments. I drilled a couple holes through the front cross member and temporarily clamped it in place for a few rolls, then bolted it down when she went straight.

I agree the best dolly design for this would be a ground-hugging one with 'stand offs' supporting the wings, ideally well away from where the props would go upon takeoff.

I hear what you're saying about the tabs' pressure on the wings affecting the pitch angle. Since they touch just about exactly on the plane's fore/aft CG and the dolly has a relatively low mass and rolling resistance I don't think there will be enough time and force to dramatically upset the balance though.

Another fear I had was if one wing cleared it's tab before the other, and the trike tipping forward. But I think that as long as the climbout is quick she'll be free of the dolly and (hopefully) powering up up and away!

Will think about it some more. Making a new dolly will be less work (and less mental pain!) than rebuilding the plane...
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Old Dec 21, 2012, 06:57 AM
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Australia, TAS, Claremont
Joined Jul 2012
77 Posts
Hey Kurt, looking good, shame about the 1st attempt.
Good luck with the next try, would love to see some video of it if possible
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