RunRyder RC
WATCH
 1 page 209 views Post Reply
Home✈️Aircraft🚁HelicopterHelicopter Main Discussion › Jetcat PHT3-3 turbine adjustments
11-27-2020 09:50 AM  60 days ago
Topic Vote0Post 1
Jethrow Tull

rrNewbie

uk

MyPosts All Forum Topic
Jetcat PHT3-3 turbine adjustments
Can any one tell me if the jetcat turbins can be speed adjusted. I have a PHT3-3 in my Verio Bell 212 running a standard 2 blade head. I have been advised if I changed the head from 2 blade to a 4 blade head, I should consider reducing the head speed from 900rmp down to 800-850rpm? Can this be done or will the standard PHT3-3 head speed work on the 4 blade setup.
SHARE  PM  EMAIL  Attn:RR  Quote
11-27-2020 05:47 PM  60 days ago
Jerry K

rrKey Veteran

Houston Area

MyPosts All Forum Topic
I have never run the Jetcat but I have run a Wren 44 and a bunch of thrust turbines in Jets. I also have not run your heli frame (I fly a Trex-700T frame which is pod & boom) but I have to assume you cannot change the drive ratio, which would be best. But your turbine has a throttle on it they all do. Your head speed is governed by the throttle curve you set in your radio, up to the max RPM of the turbine. Obviously you cannot go over that number. The head speed of your heli is calculated by the reduction and the max turbine speed. Then if you want to run a slower HS, just throttle the turbine back.

You are not asking for much of a reduction from 900 to 850 -800 something <10%. My turbine is a two stage with a PT which is slightly more forgiving than yours, which I believe is a shaft driven system.
My PT has a GB with a 4.285:1 then the heli has another reduction of about 8-9:1 giving me a HS of about 2000-2100 RPM The GP runs at 185,000-195,000 max.
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
11-27-2020 06:39 PM  60 days ago
Notar

rrKey Veteran

Taxachussetts

MyPosts All Forum Topic
Jerry
There is no throttle curve to program on a Jetcat, it is in the computer, and you can set the rpm to a certain degree. The throttle curve in the radio is not touched, from the stock linear setup, and throttle is attached to a three postion switch which is used to control start up, full idle, and full rpm.
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
11-28-2020 02:19 AM  60 days ago
Jerry K

rrKey Veteran

Houston Area

MyPosts All Forum Topic
Thank you Notar! Like I said I have never run a PHT3. But I still have to assume you can set the Max RPM in the EDT? If so you would be setting the HS? I have run a lot of JC's but they were thrust engines. My Wren, I run it just like a Nitro engine with a V-curve, in the throttle curve so as my pitch goes up so does my GP RPM. I believe I have it set to max at 195,000 at full pitch and about 185k at zero pitch.
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
11-28-2020 09:36 PM  59 days ago
Notar

rrKey Veteran

Taxachussetts

MyPosts All Forum Topic
Yes, max rpm can be set in the ECU. You can bring it down as well.
That would lower the head speed.
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
11-29-2020 08:41 AM  58 days ago
Jethrow Tull

rrNewbie

uk

MyPosts All Forum Topic
Hi chaps. Yes Jerry, my switch control:- off/check&test/start/. Following a successful start & idle returning the switch back to check & test (center position) allows the computer to reset. switching back to start once again will ramp the turbine to design speed aprox: 900-940rpm (head speed). As I have never attempted to go into the programming stages of the ECU i could do with some guidance.
SHARE  PM  EMAIL  Attn:RR  Quote
11-29-2020 11:58 AM  58 days ago
Notar

rrKey Veteran

Taxachussetts

MyPosts All Forum Topic
Contact Modtron at Vario UK. He will be glad to help with that i am sure.
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
11-30-2020 08:36 AM  57 days ago
Jethrow Tull

rrNewbie

uk

MyPosts All Forum Topic
Chaps. Notar, yes had a chat with Nigel at Verio uk. Evidently the PHT3-3 is unable to be speed adjusted, this is owing to design spec/power arrangements. The turbine installed in my Bell 212 has a slightly different gear ratio from the turbine drive set, mounted in the Bell 412. This gives the Bell 212 4 blade head a slightly reduced head speed. If I want to fit a 4 blade head, i will have to send it back to Jetcat 500-600 euros!!
SHARE  PM  EMAIL  Attn:RR  Quote
12-08-2020 02:25 PM  49 days ago
MattJen

rrElite Veteran

UK

MyPosts All Forum Topic
yeah unfortunately it will need a gear change, as the Jetcat is designed to run at 100% then is geared down via pullies and pinions to a set head speed,my hotcat and EC135 was geared 1240, but when i wanted to put it in a 1/4 scale it had to be changed so it would output 950rpm.
Most of us when flying a Jetcat, fly all the time using an idle up 1 which is 100-100-100-100-100 so you fly collective only, then when you land click out of idle up and allow turbine to settle down before you lower trim to stop or as i did have a cut..

good luck, Modtron is great guy to deal with.
All The Best
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
WATCH
 1 page 209 views Post Reply
Home✈️Aircraft🚁HelicopterHelicopter Main Discussion › Jetcat PHT3-3 turbine adjustments
Print TOPIC

 1  Topic Subscribe

Wednesday, January 27 - 4:19 am - Copyright © 2000-2021 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online