CNC Machining
RC Helis & Planes

-Hirobo GPH 346-

FOR SALE: GPH Mechanics, Muffler, Extra Parts, WRITE ME IF YOU'RE INTERESTED.

*** Order of Page ***

- Second CNC Part
- CCPM-ing The GPH
- Current Flight Log
- Looking For More GPH Sites

Don't forget to check out the other parts made for the GPH!! Click HERE

Engine  O.S. Max .46 SXH (now in Ultrasport 40 with head cut down on lathe)
Muffler  Century Hatori Copy
Radio  JR 8103 FM, JR receiver
Servos  Cyclic: Hitec 545
 Tail: Hitec 525
 Throttle: Hitec 525
Gyro  CSM 540 HH
Fuel  Coolpower 15%
Battery  1200 mah
Glowplug  O.S. #8
 Main Blades  FRP from HERE, unbelievable price! (do a search with FRP)
Tail Blades  KSJ
Paddles  Hirobo with weights removed

Second CNC Part, Tail Fin Mount for the GPH!
10.2 Grams (1-5-01)

finmount.jpg (76152 bytes) finmount4.jpg (71860 bytes)

This is a rear fin mount made for the GPH 346 and was one of the FIRST parts made on the CNC setup. It took me quite sometime to figure out how to draw this part in CAD (computer aid design), convert the code, hold the part, and then finally figure out how fast to machine the part. Overall the part came out perfect and actually fit to tightly! This part, as well as the others, are on the GPH and so far performing flawlessly :) 

"CCPM-ing" the GPH! with the least amount of modifications to the frame !
All parts are made manually on my lathe and/or mill

gph2.JPG (15511 bytes)
First you need to take the swashplate apart which is pretty easy. Unscrew the 4 screws, remove the balls, and push the top portion out of the bottom. You can also buy a CCPM swashplate, just make sure its for a 10 mm main shaft. 

NOTE: You can use the same swashplate and use 90 degree CCPM. 120 is more stable but 90 should work.

gph3.JPG (20130 bytes)
Here is the "billet" of aluminum (man I have always wanted to say that :) that will become the lower portion of the swashplate! Thanks Jack for sending me some! I plan to make it with 3 points 120 degrees apart and another point for the anti-rotation link. Here we go :)

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Here you can see the middle of the aluminum bored out for the 32 mm bearing.  The hardest part of the whole project was thinking of how to make it.  Plan out your projects, where and how far to cut and if you're going to need to remount the piece. The jaws of the chuck here are reversed. The 32 mm bearing fits perfectly, NO PLAY!

gph5.JPG (24272 bytes)
I found that no matter how well you machine, if you REMOUNT a part you will probably have to dial it in to get it straight. KEEP THIS IN MIND.

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I completely bored through the aluminum and made a "step" for the top portion of the swashplate. The outside is now cut to shape. I had to flip the part over a few times and EVERY TIME I did I had to dial indicate it in! Once a part is mounted, do as MUCH work on it as you can before removing it. 

gph7.JPG (23724 bytes)
So far it looks like a little bowl :)  Time for the mill to finish it up!

gph8.JPG (20472 bytes)
I put the jaws on the chuck the normal way and remounted the piece. The piece is still held in the "reverse" way. The swashplate is taking shape.

gph9.JPG (23348 bytes)
Here I am drilling 4 holes that will be tapped to hold the bearing in. Very easy with a rotary table.

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Here is the bottom where the 4 screws are. ALL DONE!

gph11.JPG (17851 bytes)
Here we are! Actually I must say the picture makes it look much nicer then it is. The finish is not as good as I had hoped and there was quite a bit of hand filing that was needed. I think more patients, better endmills, and more measuring would of made it "nicer."

gph12.JPG (20601 bytes)
Time for mounts on the GPH. I bought some 1/8" right angle aluminum from Home Depot for this. Cut it to size and mount it up. The mounts are held by the main bearing block screws.

gph13.JPG (10991 bytes)
Here you can see the 2 servos mounted. I am going to see if I can get the angle of the pushrods less. I plan to use 3 Hitec 545s.

gph14.JPG (18782 bytes)
These where made manually and quickly, you would be surprised to know how easy it is to make these .  It's time to get this done and flying! If this whole setup works I may remake these nicer. The arms are tapped for 3 mm setscrews and mostly made on the lathe with 16 mm between the pivot point and ball (same as servo horns). I probably replaced about 50 parts for these and some weight!

gph15.JPG (23508 bytes)
Here is the full setup! IT WORKS!!!!! This is a picture from the front to show the setup of the elevator mechanism. 

gph16.JPG (41300 bytes)
I tried every position for the elevator servo and this is the best place I came with for this setup. The main problem I ran into was the starter bearing kept getting in the way. Time to test fly it!

IT FLIES!!!! Its very smooth and the setup is simple now that I know how to use the radio's CCPM setup properly. Next heli will defiantly be CCPM!
Total Time: about 16 hours

clips.JPG (20687 bytes)

One of the things I have always hated about the GPH are the 4 canopy screws! Its such a pain to find the holes for the screws not to mention putting them in and take them out every time you want to check something. Finally, I've made new standoffs with holes for body clips! No more finding the hole for the canopy and no more screws. 6-10-02

UPDATE: 7-16-02
I 'm finding the elevator bellcrank touches at full + pitch and full forward with the starter bearing. Not that I do to many outside loops, (1 to this date hehe) but  I think I may just get rid of them and mount the elevator servo on the back for a direct link to the swashplate.  I also find my throws are not the same throughout the full pitch range, but this is probably do to the fact that 16mm is not the optimal distance (remember I just choose 16 :)  It however rolls and loops mighty quick! Also, I Love the canopy mounts, it's so much easier to work on the heli at the field!

Flight Log 2003

Date '03


8-18 I finally took the GPH out again after sitting for over 1.5 years. The OS started right up and never missed a beat. It ran perfectly! Surprisingly, a lot of the flying came back to me. I did get a little ahead of myself and while doing a practice auto (the only one) crashed it. I swear I was going to turn off the throttle hold and go back up. Damage? Not to bad, just the main blades, boom, tail pushrod and back fin. I ordered parts from Rick's and had them 2 day aired. I ordered FPR blades for the first time and can't wait to try them out! I quickly turned two ends for a carbon push rod for the tail. They are epoxied and work great. For FRP blades check out this place HERE and do a search for "FRP" best price around!
8-21 This is the FIRST time I am flying REAL main blades, not woodies. I am using the FRP Fun Key blades and they are excellent. Just bolt and fly. I cannot BELIEVE the difference!! The heli is on rails and loops, rolls are smooth. I have not tried an auto with them yet :) The GPH is flying GREAT!
8-25 I have been flying almost everyday and the GPH is doing great! The main blades are awesome and I will never go back :) I am getting very comfortable with rolls, both directions, loops, split-s, and even some inverted flight. Today, I did my first loop with a pirouette at the top and a "U" maneuver where the heli is inverted and moving backwards. I love it!
10-7 GPH is going back to mechanical mixing. Now that I am getting into more acrobatics I am finding some cross coupling.
12-15 I bought a Raptor 50V2 with new OS 50! Click here to see the raptor.





Looking for more information on the GPH-346? Try out these great sites! 

Blowup Parts Drawings Scott's Site

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