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HomeAircraftHelicopterAntiques or Out of Business › Kavan Jet Ranger headspeed
02-05-2010 07:31 PM  8 years agoPost 1
Graeme R H

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Berkshire UK

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I did a search and couldn't find the answer.
I am about to get my original Kavan jet Ranger out of storage and prep it for flying soon.
It is fitted with Futaba 148 servos and a Futaba 154 mech gyro.
I only intend to fly gentle circuits with it now and again. What would the ideal headspeed be? It uses a Webra speed 61 with the original muffler.
Thanks guys.

Why fly the rest when you can fly the best. What are the best these days anyway ?

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02-05-2010 08:16 PM  8 years agoPost 2
v22chap

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Granger, Indiana

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That is a good question ... as back then we didn't have tachs.... but I would guess that with old wood blades you should be around 1150 to 1250

Also ... here is a guy that makes the jet ranger in new kit form ... maybe he can tell you now that they make them when we have tachs...
http://americanrcheli.com/categories.asp
Good luck

Larry C ----------Bergen R/C helicopters

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02-05-2010 09:06 PM  8 years agoPost 3
Dunedinflyer

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Dunedin Fl

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Head Speed
Early models ran the tail about 5000 about 950 head speed took about 9
degrees pitch to hover later on the motor pinion increased to raise the head speed to about 1250 pitch range is very limited with the
origonal servo set up i had one late 70's had a super Tigre Blue head
the best 60 of the day would overheat just hovering then the Webra Speed HP Kraft schurle engines came on the scene i put a Webra in mine had double the power didn't overheat was the best thing flying
until the arrival of the Heliboy thats about all i remember many moons
ago Dunedinflyer

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02-05-2010 09:50 PM  8 years agoPost 4
Graeme R H

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Berkshire UK

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Thanks guys, I remember my friends flying old Hirobo models with head speeds of around 1,100 and seeing Schluters running more. When Star Rangers turned up head speeds seemed to be 1,500 ish. I guessed 1,100 would do but I don't want it to be sloppy.
I have pictures of my model in my gallery if you want to see what it looks like at the moment.
I do plan to re paint it this year. Not sure what scheme. I was thinking Santini as I already have an Airwolf.

Why fly the rest when you can fly the best. What are the best these days anyway ?

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02-06-2010 08:16 AM  8 years agoPost 5
vrhc

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East Yorkshire - England

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Kavan head speed
Running about 1200 Rpm flybarless with modern heavy CF blades.

Regards Joe

www.vrhc.co.uk - The Da Vinci Mode

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02-06-2010 01:38 PM  8 years agoPost 6
v22chap

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Granger, Indiana

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excellent Joe
Does the Kavan flybarless still have the coning angle in the head or are the blades straight across like our modern day heads ???

As I wanted to use an old Kavan head I still have for flybarless as they look so scale ...but noticed it had the dihederal in the hub .
Do you fly it without any gyro stablization ??? I bet so !!!
Do you have any vids of it flying ...would love to see that beauty in action !!!!

Larry C ----------Bergen R/C helicopters

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02-06-2010 04:55 PM  8 years agoPost 7
vrhc

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East Yorkshire - England

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Kavan JetRanger Head
Hi Larry

The head of my flybar JetRanger has a coning angle but the head on the Flybarless version has no coning angle and the blades are perfectly 'flat'.

The heli is all ready for flying but the weather at the moment is not. It was originally flown without electronics however I only have a few years general flying experience and flybarless experience only with multiblade heads hovering and figure eights. I wanted to do full circuit work with this one so I have fitted the vario multiblade head gyro to ease the workload a little.

I dont have any video of this one yet but hopefully when the weather improves here I will get flying footage.

Regards Joe

www.vrhc.co.uk - The Da Vinci Mode

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02-08-2010 09:35 AM  8 years agoPost 8
heli_headcase

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Hovering around Atlanta

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Everybody...
My Supertigre G60 blue head is powering my 1974 vintage Kavan OK with a peak head speed of 1050rpm. It's the most I can squeeze out of it and still keep temperatures in the safe zone. This is using 15% nitro and the original 'skinny' Kavan main blades. The climb is rather leisurely but does fly around OK. Just don't fly in a strong wind and do a slow turn downwind without accelerating first to maintain air speed. It will sink alarmingly fast if moving along in 'dead' air.

@ vrhc: Unless thrust bearings have been installed in that 'rigid' Kavan head, be very careful of using heavy (over 130g) blades at any serious speeds (over 1200rpm). I haven't looked closely at the bearing design of my rigid Jet Ranger head but I think it uses the same bearing configuration as the standard flybar head and if that's true, there's only one, 4 x 10 x 5mm(?) bearing handling all the thrust loads. John Benerio added thrust bearings for the later model flybar head of the KJR of Andy Griffith (Baracudahockey) but I didn't ask him for details.

@ V22chap: Sure there were tachs back in the old days. I had my Heathkit "Thumb Tach" from 1970 and found out I could read tail rotor rpm from 10ft away. Knowing the heli's main rotor-to-tail rotor gear ratio made it a snap to determine head speed by simply measuring the tail speed. That's what I did anyway.

@ Graeme R H: If that Webra Speed is in good shape, you should be able to hit 1200rpm just fine. At that speed the performance will be more than 'good enough' if I use my 1050 speed as a benchmark.

There's one more thing to be very careful of other than the bearing loads in the main blade grips; That's the reliability and strength of the tail rotor output shaft. The shaft is 5mm dia where it's seen outside the gearbox. The scary part is that the shaft transitions to 4mm dia where it enters into the first ball bearing in the gearbox. If there's ANYTHING wrong with the tail blades, grips or the shaft has been contacted and bent, there's a very good chance the shaft will break right at that 5-4mm transition.

The later (can't tell what year or model version) Jet Rangers were updated with a straight-through 5mm shaft, probably when the power being pumped into the heli from better engines started to show the weaknesses in the mechanics. Higher head speeds started to make things fail so please be very aware of the speeds of things when engine power is potentially "unlimited" compared to the sub-2HP engines of the 1970's. And don't under any circumstances do what John Simone Jr did to his Kavan at the 1973 NATS: Set the collective pitch at zero deg, full throttle and lay on the ground under the spinning rotor blades tweaking the high-speed mixture for max power (rpm)! I saw his tail output shaft snap off, tail rotor blew right off the tail gearbox and straight into the air! Didn't shoot any 8mm film of that event. Sorry


HHC

So many heli's - too little time...

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02-08-2010 12:13 PM  8 years agoPost 9
vrhc

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East Yorkshire - England

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Now thats what I call an 'in depth' reply.

Joe

www.vrhc.co.uk - The Da Vinci Mode

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02-08-2010 04:00 PM  8 years agoPost 10
v22chap

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Granger, Indiana

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LOL ... well Steve I guess I need to restate that .... not everyone had tachs back then .... leave it up to you to have one back then !!!! How did we all get along without the internet to do a search and find new items back then !!!

vrhc
Thanks for the info on the flybarless head ,, that helps a lot as I was trying to make a flybarless from the stock head and it would fly but had real bad tendencys and I figured that was the problem .
Larry

Larry C ----------Bergen R/C helicopters

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02-08-2010 08:18 PM  8 years agoPost 11
Graeme R H

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Berkshire UK

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Hi, Many thanks for that info.
I knew this was the best place to ask.

Why fly the rest when you can fly the best. What are the best these days anyway ?

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02-08-2010 08:45 PM  8 years agoPost 12
GerdrrVeteran - Vellmar/Germany - My Posts: All  Forum  Topic

Kavan is just showing on Nurnberg toy fair new kits from the Jet-Ranger series 1979 imported from americanrchelicopters. Recommended engine is .70-.90 size and CCPM.

Here some pics from the Kavan booth:

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02-08-2010 09:35 PM  8 years agoPost 13
vrhc

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East Yorkshire - England

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Yeh but its not the real thing!!!!!!!!!!!!!

Joe

www.vrhc.co.uk - The Da Vinci Mode

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02-08-2010 10:46 PM  8 years agoPost 14
heli_headcase

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Hovering around Atlanta

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.70 to .90??
O. M. G.


HHC

So many heli's - too little time...

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