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model tech mach racer - 5/30/2008 1:49:52 AM   
russm


 

Posts: 358
Joined: 8/6/2006
From: waukegan, IL, USA
Status: offline 		flew mine for the first time today. handles well, but the speed even in a dive was dissapointing. i am guessing around 85 mph. have a 46ax w/ a mac muffler,9-7 apc prop,and 15% synth fuel. tached it at 14300 on the ground. i really figured this setup would be a lot faster. it is a very lite airframe and does not seem like there would be a lot of drag. any thoughts? thanks, russm
       Post #: 1

RE: model tech mach racer - 5/30/2008 3:15:13 AM   
Crazy4Flight



Posts: 2242
Joined: 9/15/2002
From: Milford, MI, USA
Status: offline 		http://www.jettengineering.com/

(in reply to russm)
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RE: model tech mach racer - 5/30/2008 3:24:17 AM   
russm


 

Posts: 358
Joined: 8/6/2006
From: waukegan, IL, USA
Status: offline 		ya,ya,ya, i already new that. have a sj50 siting on a shelf. when i put this plane together, it was in use. good answer though.

(in reply to Crazy4Flight)
       Post #: 3

RE: model tech mach racer - 5/30/2008 4:35:57 AM   
Duane-RCU



Posts: 424
Joined: 5/5/2002
From: Arlington, TX, USA
Status: offline 		I have a ST .45 with a t/pipe (maybe not tuned good yet, this is my first try) 9X7 APC, getting a little over 16,000 on the ground. Flies ok I guess, manual suggests not diving at full throttle, I guess things might blow apart (flutter!) I like how it slows down to land, this is my first delta. No radar or speed guesses, but I figure it's a little over 100mph? Nothing like when the ST was on my Viper (Jett muffler) turning the 9x7 over 17,000, that was fun...

(in reply to russm)
       Post #: 4

RE: model tech mach racer - 5/30/2008 4:56:41 AM   
freakingfast


 

Posts: 809
Joined: 1/3/2005
From: mather, CA, USA
Status: online
quote:

ORIGINAL: russm

fhave a 46ax w/ a mac muffler,9-7 apc prop14300


If you are using a BLACK Macs muffler it may not make more power than stock. A Macs tuned pipe will make more power....when the header is tuned. A Macs "pre-tuned header & pipe" is in the ballpark.

The tricycle landing gear is a ton of drag if you are using it.




_____________________________

When in doubt, give it full power. The smaller
pieces fit easier in the bag! Revver Bro #201

(in reply to russm)
       Post #: 5

RE: model tech mach racer - 5/30/2008 5:06:26 AM   
freakingfast


 

Posts: 809
Joined: 1/3/2005
From: mather, CA, USA
Status: online
quote:

ORIGINAL: Duane-RCU

I Flies ok I guess, manual suggests not diving at full throttle, I guess things might blow apart (flutter!)


I can’t imagine marketing/selling a plane that’s obviously designed to appeal to the speed minded and than tell the customer not to put it in a power dive. Maybe it’s just me.

_____________________________

When in doubt, give it full power. The smaller
pieces fit easier in the bag! Revver Bro #201

(in reply to Duane-RCU)
       Post #: 6

RE: model tech mach racer - 6/3/2008 10:11:15 PM   
georbeckha



Posts: 45
Joined: 1/27/2004
From: Evans, CO, USA
Status: offline 		I test flew my second Mach racer this past weekend.
The first one met an unfortunate end on it's maiden flight. It was powered by a Jett 50. For some reason I put the power switch in the hatch where the directions indicated. BIG mistake when after less than 2 seconds the hatch blew off. You guessed it, the switch flew off still attached to the hatch. After a graceful arc topping out about 200 ft in altitude, the largest piece left was the hatch that blew off.

Mach Racer

Anyhow, the new one I moved the switch off of the hatch (Just in case) and powered it with an OS 55 AX with an Ultra Thrust racing muffler turning an APC 10x6 at 16,800 rpm! (And that is a brand new engine with maybe less than 20oz fuel through it)
Maiden went well except for major flutter in a shallow dive. (No Damage)
After I sealed the hinge Lines and changed to a 10x7 prop with no reduction to speak of in rpm, 2nd flight went well to (Except for more flutter in the shallow dive)
Now, I'm working on sealing the hinge lines top and bottom, trying to reduce any movement in the control pushrods to try to remove the flutter!
If there is any interest, it was clocked at 124 mph on the first flight and 128 mph on the second!

Anyone else have any suggestions on stopping the flutter?
I'm also going to invest in an APC 9x8 and 9x9 props to see what effects they have on the speed etc.
Needless to say, I have a new favorite fun plane to fly!

(in reply to freakingfast)
       Post #: 7

RE: model tech mach racer - 6/4/2008 12:00:25 AM   
still4given



Posts: 463
Joined: 1/27/2006
From: Victorville, CA, USA
Status: offline 		My suggestion is to make sure you have mechanical advantage on all servos, i.e. use the inside hole on the servo and the outside hole on the control horn at the control surface. If you need more throw, increase it with the transmitter. You could also use ball joint style clevises to reduce slop. If you have sealed the hinges on one side that should be sufficient.

Blessings, Terry

_____________________________

Live simply. Love generously. Care deeply.
Speak kindly. Leave the rest to God

(in reply to georbeckha)
       Post #: 8

RE: model tech mach racer - 6/4/2008 12:51:18 AM   
Kmot



Posts: 7741
Joined: 6/11/2003
From: Northridge, CA, USA
Status: offline 		georbeckha: The remains of your Reaction 54 accident is the most amazing crash picture I have seen!

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DRILL BABY DRILL!!!

(in reply to still4given)
       Post #: 9

RE: model tech mach racer - 6/4/2008 1:19:28 AM   
russm


 

Posts: 358
Joined: 8/6/2006
From: waukegan, IL, USA
Status: offline 		tried a 9x8.75 apc prop. 15200rpm. slower yet. put a jett muffler ands 10x6 wood prop on it. will see if that helps any. geo, thanks for the heads up on the flutter. excellent #s on the radar. that is about what i am looking for.

(in reply to Kmot)
       Post #: 10

RE: model tech mach racer - 6/4/2008 4:32:04 AM   
Ed_Moorman



Posts: 3684
Joined: 1/5/2002
From: Shalimar, FL, USA
Status: offline 		I flew my 2 with a Magnum .52XLS with a Rossi short pipe and an OS .50SX with a Jett. Both used 9-7 props.

First, my testing on the black Mac's muffler is that it will cut your rpm, not increase it. The stock muffler without the baffle will be faster.

Second, a 10-7 will be a better prop for the .46AX, in my opinion. It's not a revver like the .50 or the TT .46.

Third, I always replace my pushrods on anything that can flutter with 4-40 size rods. The 2mm stuff that comes in the kit is pretty flexible.

Fourth, Mine were built without the gear and launched. Lots of drag on the gear.


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_____________________________

Ed Moorman, AMA 553, KD4QBM, Revver Bro #156
R/C Report Magazine, Fun Aerobatics Column

(in reply to russm)
       Post #: 11

RE: model tech mach racer - 6/6/2008 12:10:04 AM   
rexracer


 

Posts: 254
Joined: 1/23/2006
From: New Milford, CT, USA
Status: offline 		I don't know a lot about speed planes, but I do have a 46AX and it likes a lot of load. I have a high drag plane (Funtana 40) and I'm using a MA 12x6. It turns close to 12000 on the ground if I remember right, and unloads a lot in the air. I bet I'm getting over 14000 rpms flying into a 15mph headwind.

_____________________________

Club Saito member #173

(in reply to Ed_Moorman)
       Post #: 12

RE: model tech mach racer - 6/9/2008 1:22:05 AM   
planknheli


 

Posts: 27
Joined: 3/25/2006
From: lexington, NC, USA
Status: offline
hey ed,
i would like to put dual rudders on mine, am i crazy?? the reason i ask is on the maiden it went into a flat spin & i couldn`t pull it out so it went into a tree. we got it dwn. next flight it did it again but i clicked on the high rates & pulled it out. i let my friend fly it & guess what? inverted flat spin . before he could pull it out = deadstick. he flattened it out before it hit so there was no damage. i put the 700 mah 4 cell flat pack behind the elevon servo`s & with a magnum 52 it balanced at 8.25 . took the nose gear block out & no mains, cowl or canopy. weight is 3lbs. 4 oz. it needs alot of down ele. to hold it inverted. would this be causing it to flat spin?? i fly my 3d profiles hands off upright or inverted. i`m thinking of adding tail weight to bring the cg back but i`d rather cut out the 2 vert. stab. & add 2 rudders & the servo instead of lead. then i could flat spin on purpose & of course hover & tail touch. lol.
thanks,
conk
p.s. it climbs at full throttle. will the cg change fix this or do i need to add dwn. thrust??

< Message edited by planknheli -- 6/9/2008 1:25:00 AM >

(in reply to rexracer)
       Post #: 13

RE: model tech mach racer - 6/9/2008 8:16:49 PM   
the trums


 

Posts: 71
Joined: 8/30/2007
From: , FL, USA
Status: offline 		ses next post

< Message edited by the trums -- 6/10/2008 1:10:50 PM >

(in reply to planknheli)
       Post #: 14

RE: model tech mach racer - 6/10/2008 12:00:31 AM