RunRyder RC
 3  Topic Subscribe
WATCH
 3 pages [ <<    <    ( 1 )     2      3     NEXT    >> ] 2499 views POST REPLY
HelicopterCentury Radikal G20-30 N640 Hawk Predator › Custom beefed up lower/side frame for G20
08-21-2014 02:21 AM  3 years agoPost 1
RM3

rrElite Veteran

Killeen, Texas - USA

My Posts: All  Forum  Topic

As some of you may know I had a recurring issue with my G20 constantly breaking the lower frame on the back half. I also noticed that the both the side and bottom frames were prone to bending at other points.

So instead of ordering yet another bottom frame and side frame items, I ordered some 2024 alloy which is twice as strong as the 6061 alloy of the stock unit. I originally wanted to go with 7075 alloy but the cost was just too high for the plate i needed to cut it from, so the 2024 was a compromise in cost over the 7075 alloy. I also made changes to the thickness overall as well as changed the design to have diagonal bracing to deal with the torsional stress, in particular the rear half.

The custom unit weight is just over double, but after removing the pull start and side frame braces (no longer needed) it comes out to be about the same .

my version compared to the stock (broken) unit.
(still need to drill and tap the side mount holes)

next project is my torque dampening main gear hub... which will eliminate (ok reduce alot hopefully) the torque vibs from the engine.

showing a preference will only get you into trouble, 90% of everything is crap...

PM  EMAIL  GALLERY  Attn:RR  Quote
08-21-2014 03:10 AM  3 years agoPost 2
OuttaControl

rrVeteran

Springfield, Missouri -United states

My Posts: All  Forum  Topic

frame
Looks real good sir! I'm a big fan of machined parts. I'd like to have an entire G20 or G30 frame made out of aluminum.

Mine fall down, went BOOM!!

PM  EMAIL  GALLERY  Attn:RR  Quote
08-21-2014 05:18 AM  3 years agoPost 3
Gearhead

rrMaster

Vt

My Posts: All  Forum  Topic

boy that stroked engine has given you a lot of problems

Jim
Buzz Buzz Buzz

PM  EMAIL  GALLERY  Attn:RR  Quote
08-21-2014 05:38 AM  3 years agoPost 4
RM3

rrElite Veteran

Killeen, Texas - USA

My Posts: All  Forum  Topic

The engine runs smoothly balance wise but the torque and HP it puts out are just too much for the light weight frame.

simply put the stock frame on the G20 was never meant to handle a more powerful stroker motor.

If you really think about it, I basically put the power of a good 231 into the G20 frame, and it just does not like it.

guess thats why the G30 HP clutch it has is holding up just fine... so far.

besides, the G20 frame has a history of breaking near the rear of the frame even in stock models... some here in RR even posted a picture of thier frames breaking in the exact same areas:
PistolPete: https://rc.runryder.com/helicopter/t745865p1/
So basically the addition of a more powerful engine has exasperated an already present issue with the stock design flaw. I have had the bottom frame break before on my other stock model once. I'm willing to bet others have hairline cracks in thier frames in the same places and are probably un aware of it. This has also happened on the G30 by what I have read online.

I figure at this point I might as well frankenstien it with my evil plans till it eats the dirt hard enough to permanently bury it for good.

showing a preference will only get you into trouble, 90% of everything is crap...

PM  EMAIL  GALLERY  Attn:RR  Quote
08-21-2014 02:41 PM  3 years agoPost 5
OuttaControl

rrVeteran

Springfield, Missouri -United states

My Posts: All  Forum  Topic

frame
Frankenchopper!!!! Nice!!

Mine fall down, went BOOM!!

PM  EMAIL  GALLERY  Attn:RR  Quote
08-21-2014 05:54 PM  3 years agoPost 6
Pistol Pete

rrProfessor

Seffner, FL

My Posts: All  Forum  Topic

RM3
Looks beefy and on par with your modded engine. Great job!

Will you still be able to use the removable pull start with thicker plate?

I considered doubling the frames once but I really enjoy the removable pull start and never did it.

I havent broken a frame since that one I posted last year and despite one hard landing on the existing one that replaced it, it only took out the boom and previoulsy repaired plastic struts but no other damages...go figure. Oh yeah...one "bone" from one tail grip to slider.

Given that last hard landing, my G20 is now sporting carbon fiber boom and struts. More forgiveable for the types of autos I practice. Does not photo well as its just black and shiny.

Im in the process of ordering vibration-damping sandwich mounts at McMaster that thanks to this post I remember them used in JR Venture helis. Worth a try.

~~Enjoying the hobby one flight at a time~~

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
08-21-2014 06:15 PM  3 years agoPost 7
RM3

rrElite Veteran

Killeen, Texas - USA

My Posts: All  Forum  Topic

I can still use the pull start, I just have to add a spacer that is 2mm thicker on the pulley.

I thought about some type of bushing for mounting the engine to help isolate the vibs, but the issue is that the drive train alignment (especially the clutch) is very dependent on the rigid mounting of the engine. If the clutch/pinion assembly was completely supported by the engine itself, a vibration isolating bushing mount to the engine would work.

showing a preference will only get you into trouble, 90% of everything is crap...

PM  EMAIL  GALLERY  Attn:RR  Quote
08-21-2014 06:48 PM  3 years agoPost 8
Pistol Pete

rrProfessor

Seffner, FL

My Posts: All  Forum  Topic

Done ordering a set of four 9247K31.

I'll be "testing" between truts and frame. Should help cushion hard landings.

Keep on machining!

~~Enjoying the hobby one flight at a time~~

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
08-21-2014 07:11 PM  3 years agoPost 9
Gumbomb

rrNovice

Northwest England, UK

My Posts: All  Forum  Topic

G20 FRAMES
RM3

Lovely machining job,

I must admit i've never had a problem with stock frames failing even with a Wally motor but i'm only a sport flyer.

Keep up the good work.

My gasser might not be light but it can fly better than I can fly it

PM  EMAIL  Attn:RR  Quote
08-21-2014 09:37 PM  3 years agoPost 10
RM3

rrElite Veteran

Killeen, Texas - USA

My Posts: All  Forum  Topic

thanks for the kind words.

I just finsihed installing the bottom frame.

I noticed after installing it that the two CF/G10 side frames were not quite aligned to the pinion block after they were bolted to the new bottom frame. The bottom frame was machined to within 0.001 inch and is "squared up with the world" as we say in the machining world. so this leads me to belive that the side frame may be manufactured with some "interesting" tolerances that required me to dremel the holes for the pinion block into proper alignement for the clutch assembly.

I also noticed that I did not need the pulley extension for the the pull start. I had an extra plate previously installed, so removal of it brough everything back into reach for the pull start pawl.

its a very robust frame, but only long term flight testing will determine the worth of this project.

testing to come, weather permitting (30mph gusts right now, not good for vids )

showing a preference will only get you into trouble, 90% of everything is crap...

PM  EMAIL  GALLERY  Attn:RR  Quote
08-22-2014 08:38 PM  3 years agoPost 11
Pistol Pete

rrProfessor

Seffner, FL

My Posts: All  Forum  Topic

The custom unit weight is just over double, but after removing the pull start and side frame braces (no longer needed) it comes out to be about the same
I would leave the side braces on as they also attached to the upper bearing block...food for thought.

Today I had an unusual shake at spool up. Lasted longer than the usual first flight blade out of position 5 second shake. It's definitely the bell bearing. I can move bell up and down a mm from either side. It lasted 13.5 gallons. Not bad? No clue.

~~Enjoying the hobby one flight at a time~~

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
08-23-2014 04:42 AM  3 years agoPost 12
RM3

rrElite Veteran

Killeen, Texas - USA

My Posts: All  Forum  Topic

your probably right that your bell bearing is done... I used to have issues with the lower bearing in the pinion block and the lower of the two upper bearings as well. It seems that if the clutch bell and start shaft don't line up perfect or are not supported enough the bearings suffer. I actually ruined one bell as the bearing wore a rut on the aluminum just before it ate itself and dumped the steal balls into my clutch... the plastic block is very sensitive to the pressure from the eight mounting bolts. too loose and it moves out of alignment, too tight and you put un even pressure on the bearing causing it to eat itself up over time.

With the aluminum block I have my bearings have lasted since its installation... like a year now I think.

Yeah as for the side frame braces, I had to put them back on, cause my RPM sensor is mounted to one of them to read the magnets mounted in the main gear.

showing a preference will only get you into trouble, 90% of everything is crap...

PM  EMAIL  GALLERY  Attn:RR  Quote
08-23-2014 01:24 PM  3 years agoPost 13
Pistol Pete

rrProfessor

Seffner, FL

My Posts: All  Forum  Topic

Update...
It ended up being the 10*15*4 bearing that supports the top of the pinion (as in second bearing from top ).

The "suspected" Bell bearing is still good and loctite in place. Good news for me as I had what I needed in stock. A good cleaning and overall inspection and she is good to go to finish off gallon #13 today.

I did notice one ear of the clutch with a larger gap than the other side. Not much but I suspect its what may have killed that bearing. Lets see how long before it goes or another/same bearing.

FWIW...I only use corrosionX for lubricant.

I hand spin starting shaft while torquing down clutch assembly to "feel" its still spinning bind free all the time. Perfect? Heck no, but I like to call it "within gasser tolerance"

~~Enjoying the hobby one flight at a time~~

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
08-23-2014 04:17 PM  3 years agoPost 14
RM3

rrElite Veteran

Killeen, Texas - USA

My Posts: All  Forum  Topic

I hand spin starting shaft while torquing down clutch assembly to "feel" its still spinning bind free all the time.
I used to do this as well... Then one day I had installed a new G30 clutch (first time in the modded G20) with new Bell... I would check the spin of the start shaft when aligning the assembly. I then noticed that the clutch was not sitting in the bell evenly. It was canted slighty. The tolerances of the plastic block are sometimes questionable and I wonder if a "bad" one causes a false alignment. Sometimes i would have issues after doing the final torque of the pinion block bolts... it would get fustrating sometimes getting everything perfect.

showing a preference will only get you into trouble, 90% of everything is crap...

PM  EMAIL  GALLERY  Attn:RR  Quote
08-23-2014 11:08 PM  3 years agoPost 15
Pistol Pete

rrProfessor

Seffner, FL

My Posts: All  Forum  Topic

Four flights today and all is good.

While on the subject of aligning...what has worked for me "so far" in order of execution: (for noobs...not RM3 )

> adjust bell/pinion for proper mesh to main gear first. Tighten socket head cap screws just enought to keep it from shifting. I dont use the fancy dressing washers here as the G10 frames hold well. Main gear spun for high spots

> engine in place but loose in frame for later adjustment

> position built heli over engine/frame and bolt side frames down to engine frame including the two in the bottom but not the fan plate.

> torq down engine to frame while spinning the starting shaft. First two screws cross diagonal to each other.

> finish torquing down clutch housing while spinning main gear for free spinning and also starting shaft. While doing such, if either one starts to feel like its binding, I slightly back off on that screw until free spinning restored. (repeat per screw)

As Im using blue loctite, they will stay in place without over torquing and causing a bind. Maybe it's time I get a Wiha torque screwdriver...hmmm.

I can honestly say that this is the first bearing that I have actually killed by flying the crap out of it as opposed to crashing it.

Figured the tail rotor bearings would have gone first.

~~Enjoying the hobby one flight at a time~~

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
08-24-2014 03:49 AM  3 years agoPost 16
Gearhead

rrMaster

Vt

My Posts: All  Forum  Topic

well we know the stock "Hex Spacers" (52.75mm) for Plastic Bearing Block are a bit too short, my measurement show about 1/2mm (.020) too short, but you can buy 2 packages of Hex Spacers #HW3127, these Spaces are longer (55mm) and can be shorten to the correct length..

be sure if you do buy these longer Spaces that you use a Lathe to shorten them and not a File, because the lathe will give the Spacer's Ends a much needed straighter cut than a File will,, also you need to shorten each Spacer on Each-Side so you do not shorten the Threads to much on one side

#HW3127
http://www.centuryheli.com/products...tm?prtnm=HW3127

Jim
Buzz Buzz Buzz

PM  EMAIL  GALLERY  Attn:RR  Quote
08-24-2014 03:44 PM  3 years agoPost 17
RM3

rrElite Veteran

Killeen, Texas - USA

My Posts: All  Forum  Topic

the issue with that idea is that not everybody owns or has access to a lathe, dial caliper and other mechanical tooling.

Parts should fit properly and tolerances maintained, but considering the MSRP price for the kit of $200 I can imajine what the actual cost of manufacture is probably well under $75.

but I agree, you want cheap, you gotta be willing to play on the bench...

showing a preference will only get you into trouble, 90% of everything is crap...

PM  EMAIL  GALLERY  Attn:RR  Quote
08-25-2014 02:21 AM  3 years agoPost 18
Gearhead

rrMaster

Vt

My Posts: All  Forum  Topic

smaller bench lathes are everywhere, and usually caliper "hang" with lathes, actually, if you can find some one that has been around lathes a while they really don't need calipers to do this simple job, I know I don't need them to do this job

Jim
Buzz Buzz Buzz

PM  EMAIL  GALLERY  Attn:RR  Quote
08-25-2014 11:25 AM  3 years agoPost 19
Pistol Pete

rrProfessor

Seffner, FL

My Posts: All  Forum  Topic

No lathe? Drill + disk or belt sander and a ruler for the non engineer-modelers.

Finished 13th gallon yesterday. Onward.

~~Enjoying the hobby one flight at a time~~

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
09-02-2014 03:24 AM  3 years agoPost 20
strat1960s

rrApprentice

San Antonio Texas

My Posts: All  Forum  Topic

This is awesome guys. I really appreciate all the information you are sharing.
I don't fly my G20 near as much as I want to or should. I've only replaced my blade grip bearings. All other bearings are original from when I built it 4 years ago.

Ted

I always have fun. Some times are more fun than others.

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
WATCH
 3 pages [ <<    <    ( 1 )     2      3     NEXT    >> ] 2499 views POST REPLY
HelicopterCentury Radikal G20-30 N640 Hawk Predator › Custom beefed up lower/side frame for G20
 Print TOPIC  Make Suggestion 

 3  Topic Subscribe

Monday, May 21 - 2:13 pm - Copyright © 2000-2018 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online