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HomeAircraftHelicopterGasser Model RC HelicoptersOther › T-Rex 600 Gas Conversion
01-18-2009 05:11 PM  9 years agoPost 21
Sarcelle

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Cherbourg low NORMANDY FRANCE

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Thus on my RAPPY Gasser I will could NHP 710mm with a tube AC of Rappy 90 and one modif AC with belt and generator with Nimh accumulators of 1500mah

Filou the WILD duck !!!!!!

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01-18-2009 05:14 PM  9 years agoPost 22
pgkevet

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Wales

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..thinking too much..

I'm guessing that blade length and headspeed is a more complex issue?

Increasing headspeed alone produces more lift for same pitch but there must be a relationship between that headspeed and the availability of clean air and drag on the blades.. although (of coures) things like a trex 250 run at ridiculous headspeeds.

There's also going to be an obvious issue of downdraft onto the heli frame but with soemthing designed around a 600 frame that shouldn't matter.

As a guesstimate if a 600n runs around the 2000rpm headspeed and you add 30% more mass (another kilo of engine) then either you need a substantial increase in pitch range with more torque or a significant increase in headspeed = forces on the grips.

So with all things being compromise what pinion do you need to give a headpseed around 2200 on a more torquey engine and keep engine rpm around the 12000. That's a ratio of 5.45. 600N has main gear of 170T so looking at pinion of 31T ???

pgk

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01-18-2009 05:18 PM  9 years agoPost 23
Sarcelle

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Cherbourg low NORMANDY FRANCE

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But there in this moment I always have my problem of delivery with “DHL” which is saying does not find me at home Bizarre because I am there and thus I am rather dissatisfied of this company which crit which one is with his maltreatment whereas it is a service of service public!!
Not to find me at the end of 4 tests and to return the parcel to England it is not commercial it should touch the money only if the purchaser has really his parcel!!!

DHL does something or I will make you a malicious publicity!!! ; O))))

Filou the WILD duck !!!!!!

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01-18-2009 10:08 PM  9 years agoPost 24
puneetp

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Bangalore, India

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2 queries

what your AUW ?

Also how much power is the 23cc producing compared to a .50 size engine running CP1 15%

Machine over Gravity

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01-18-2009 11:10 PM  9 years agoPost 25
unochen

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Taipei,Taiwan

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Headspeed and gear ratio's
Butting in!

MAX Headspeed varies with pitch. So if you take a heli and set the headspeed to 2000 rpms with a top end pitch of +12 degrees for example and climb out, it will bog down to a certain point and then maintain that headspeed. For example, a G26 with SAB 710's can swing the blades with 11 degrees of pitch on a tempest head (wider than a 3D head) at say 1750 rpms. If you drop the pitch to +10, it can sustain 1800 rpms. These are examples, not actual figures but they are close to what I remember from my tests. Probably no machine is going to sustain 2000 head speed unless you drop the top end pitch down to single digits (or change to smaller blades)

Gear ratio is like 3rd or 4th or 5th gear in a car. The lower the gear ratio the steeper the mountain you can climb with lower headspeed. In other words the faster the G26 turns, the better it can lug a particular head speed. But faster engine means slower headspeed and you got to find an ideal GR for the target headspeed we like to run. This is not a big as a deal as what the motor can do with whatever size blades and pitch, its more like a fine tuning adjustment. In other words, small gains from adjusting the GR.

Lastly, if you go full throttle full pitch and let it climb, if it can maintain it (example 1750 head speed) it will all the way up as much as you can wait for it with no bog. Its not like its going to start bogging and keep bogging within eyesight. However, if you were on camera video flying yes definately it will bog down as you climb through 5000 feet and more through 10000 etc as the air will get thinner. Also, if its not loaded enough it will accelerate on the way up (rpm wise from the ground up within sight) until you reach the full power of the engine.

-=>Raja.

hp = (torque * RPM) / 5250

OS91 3.4 hp @ 15,000 rpm
3.4hp = (torque *15,000RPM) / 5250
torque = 1.19ft-lb

G20EI 1.73hp@11.000RPM
torque = 0.826ft-lb

G231PUH 2.15hp@13.000RPM
torque = 0.868ft-lb

G260PUH 2.33hp@13.000RPM
torque = 0.94ft-lb

G230RC 2.93hp@14.000RPM
torque = 1.099ft-lb

G260RC 2.99hp@14.000RPM
torque = 1.12ft-lb

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01-18-2009 11:55 PM  9 years agoPost 26
Fixit

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UK

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Thanks for the input unochen that was very informative and will answer the questions people are asking me on this thread I'm sure,
I must admit I’m very close to your predictions with this machine, I have it set at +10 1800 with 680 blades.
Cheers

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01-24-2009 05:43 PM  9 years agoPost 27
Fixit

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UK

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I had a couple more flights with the 600/231 today and I just love this machine, although it’s a gasser you don’t get that feeling that its heavy at all in fact it just feels like your flying a nitro.
I still need to run the engine in but everything else seems well matched.
T-Rex 600
G231PUH
Gearing 6.29:1
700 Boom
680 Blades
12000 RPM
1905 Head Speed
+10 -5 Pitch.

I wonder what this Heli would be like with a Hanson engine and a good pilot

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01-24-2009 06:16 PM  9 years agoPost 28
Dr. Fibinotchi

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Sioux Falls SD

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hehe
Sounds like fun.

I think you could send that engine off and get more torque out of it to put more pitch in the blades.

-Cody

If you want others to be happy, practice compassion. If you want to be happy, practice compassion.

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01-24-2009 06:38 PM  9 years agoPost 29
Fixit

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UK

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I think you could send that engine off and get more torque out of it to put more pitch in the blades.
Yes I’m sure I could but I will be more than happy in its present state of tune, I was just thinking out loud

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01-24-2009 07:02 PM  9 years agoPost 30
copperclad

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NY

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although it’s a gasser you don’t get that feeling that its heavy at all
Hi Peter

it's 10 degrees Fahrenheit here , and you are giving me flying fever , sounds like a great conversion , i want one , cheers

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01-24-2009 08:02 PM  9 years agoPost 31
Fixit

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UK

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Hi Dana
it's 10 degrees Fahrenheit here , and you are giving me flying fever , sounds like a great conversion , i want one , cheers
Well that’s how I got in this mess in the first place watching your 600 gasser thread

Glad you like it, how’s its brother doing?

Man that sounds cold, guess your sticking to indoor flying.

PS
It’s about 6°C and we still make it too the club every week

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01-24-2009 08:12 PM  9 years agoPost 32
copperclad

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NY

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Hi Peter
anything below 20 degrees fahrenheit , and i head for the shop

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01-24-2009 08:47 PM  9 years agoPost 33
Fixit

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UK

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Hi Dana

You do right I must admit I have worked all week on this heli again and really wanted the rewards of seeing it fly today otherwise I would have stayed in the house myself

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01-24-2009 08:53 PM  9 years agoPost 34
copperclad

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NY

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Hi Peter
LOL , you would have had your pudding too

i have a couple of projects i have just finished , and with this cold , there is no hope of flying till things warm up a bit

.

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01-24-2009 10:32 PM  9 years agoPost 35
zorba

rrApprentice

Montreal, Quebec, Canada

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Hi Copperclad, i feel the same way. I finished the Raptor 60 conversion and is sitting there, I also finished all the bling stuff on my predator and it sitting there also. They both look at me with anticipation.

Now I'm starting on a 600 conversion and it will finish before spring gets here.

You are more south than me you will fly before I do.
I hope you can post the results on here so I can make changes on mine before flight.

Anyway I've been following your's and Fixit's threads onthe conversion and I take my hat off to both of you..
I will keep you posted.

Cheers

3-450's,rex500ESP,rex600G,Rex700G,Raptor60G,FreyaCW-EXII, VarioEC155, Logo20, Cessna310,CL-415,

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01-24-2009 11:26 PM  9 years agoPost 36
copperclad

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NY

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Hi Zorba

Yow! Montreal has to be cold this time of year , i looked through your gallery and your R-90 conversion looks great , you have some great looking machines , i think having long winters , gives us an advantage in the building department , with plenty of shop time , regards

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01-25-2009 11:20 PM  9 years agoPost 37
Fixit

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UK

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LOL , you would have had your pudding too
Thats a good piont

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01-31-2009 05:57 AM  9 years agoPost 38
JMTrex

rrNovice

Pasir Gudang, Johor, Malaysia

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Wow! A sure great stuff here.
Hi All,

I 'm new to Heli. Recently bought a Trex 600N belt with OS Hyper50+ Hatori n Funkey Fibre Blade n JR388 control. Like to modify things esp if it save on the long run or better performance local store run short of Nitro supply from time to time b'cos of the RC Heli fever. Sounds like a good idea to do convert to gas. Thanks Fixit and all for the input..Happy Flying.

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02-09-2009 04:59 PM  9 years agoPost 39
ranger-7

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Nürnberg / Germany

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Hi Fixit,
could please help me out i've seen your cooling tunnel on our conversion, how did you done it ?? have you got some cutting strickle ??
i will put on my zg20 a bigger cooling fan maybe this from loetterle from the raptor 90 its got a diameter about 65mm like the orginal trex 600 but a height about 25mm so i have to built a new cooling tunnel because the t-rex 600 ones has a height about 14mm,
i think i will provide a much better cooling benefit

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02-09-2009 06:13 PM  9 years agoPost 40
Fixit

rrElite Veteran

UK

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Hello ranger-7, On booth my 600 conversions I used the Fan Hub, Shroud mounting Plate and the cooling Shroud from the Century Predator Gasser, this isn’t a cheap way of doing it but are philosophy was to use the best available for the job to insure good cooling with maintenance free flying.
I also used the Predator 90 Glow clutch and starter shaft on the latest conversion but this means machining the bell to take the 600 pinion thread.
Another option might be to look at using the Quick Bat gasser cooling parts.

Hope this helps.

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HomeAircraftHelicopterGasser Model RC HelicoptersOther › T-Rex 600 Gas Conversion
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