3 or 4 blade tail rotors for Logos?

Hi,

I have a Logo 500 in a fuselage with a 4-blade head (4x 620mm). The lowest I can go on the head speed is 1250 and still have useful tail authority, and that is with 95mm semi-symmetrical tail blades. I can't go any longer on the tail blades due to a horizontal stabilizer at 98mm from the hub.

My question: Are there any 3 or 4 blade tail rotor units that work with the Logo 500/550/600 series (22 & 25mm booms), or can be modified to work? I have a 550 and 600 that I also run at low speed that are in need of more tail authority, and using really long tail blades just doesn't look right.

Any suggestions?

Thanks!

Hi,

I'm not aware, but I guess any tail rotor which fits the tail shaft and has a suitable tail pitch slider, could be made to work. It's probably necessary to also use the bell crank which goes with it, and adapt it to the tail boom somehow, or mix parts.

E.g. VARIO offers 3-bladed tail rotors for 5 mm tail shafts, and control bridges, sleeves etc.

Kind regards

Eddi

Born to fly ...
forced to work.

Another Option would be to check if there is a tail gear wheel for the belt available with 1 tooth less somewhere at industrial shops ...

regards (EN) / Gruss (DE)

Rainer Vetter

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Thanks for the suggestions. I did some looking around. The Vario option is definitely not cheap, but looks like it would work if nothing else does. I noticed that the Goblin 770 Sport has a 3-blade tail, but it's a 6mm shaft. I can change everything over to 6mm, except the tail pulley. I would have to drill that out. Not sure if I could hit dead center with a drill press. No lathe in sight.

I see the 690SX main pulley lists 80 teeth (05112). Is that more or the same number of teeth as the standard plastic one, and will it fit on a 600SE/SX?

Hi,

the belt on the 690 has a different tooth pitch, and with the corresponding main belt pulley, you are back at where you were ... no option.

6 mm could also work, if you used a sleeve 5x6x0.5 mm to adapt the tail rotor hub, but that would still leave the 6 mm control bridge.

Kind regards

Eddi

Born to fly ...
forced to work.



Edited 1 time(s). Last edit at 08/01/2019 08:53AM by Eddi E. aus G..

Looks like the Vario option is the most workable. I've already used their tail pitch arms to move the tail to the left on 3 other helis so I know that will fit. I'll need to save up for the other parts (hub and bridge) though. The 4-blade unit will run me about $265. The 3-blade unit is only $15 cheaper. I don't think EastCoastVario ever does sales.

Thanks for the suggestions!

What about a tail hub from Roban/Scaleflying?

My Roban Bell 429 has a 4 Blade Tail ...

regards (EN) / Gruss (DE)

Rainer Vetter

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Any idea where to find one? The Roban site shows parts as "Under Construction" and the 2 US distributors don't seem to carry parts for the mechanics.

https://scaleflying.de/?language=en&cat=c36_Heckrotoren-Heckrotoren.html&cPath=36

regards (EN) / Gruss (DE)

Rainer Vetter

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Posting and answering - please use a PC and a standard keyboard. Answer all questions fully, take the needed time, don't forget probably requested attachments.

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That's certainly a better price, at least before shipping. I requested a shipping quote, hopefully it's not too outrageous, but at least they should deduct the VAT.

Do I need to get the L-lever set, or will the existing Mikado one work? Is there anything else I should order from them.

Thanks!

Hmmm - i don't know. Probably haved a look in the manuals there or ask them.

I could have a look at mine - but i am afarid i won't see enough …


https://www.vstabi.info/forum/read.php?10,155184,page=1

regards (EN) / Gruss (DE)

Rainer Vetter

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Posting and answering - please use a PC and a standard keyboard. Answer all questions fully, take the needed time, don't forget probably requested attachments.

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I found a manual for your 429. It looks like the ball will mate up with the normal Logo pitch arm, but I'll go ahead and order the Roban ones just in case. Based on the shipping costs, it's easier to add the 4 Euro part and not need it than have to make another order.

The Scaleflying.de people are on summer vacation anyway, so good thing I'm not in a rush

Thanks!

I started to do the same research.

Both Align and SAB make 3 bladed tails.

I know the Align H70T008xx for the 700 is made for a 6mm shaft. They also make a 3 bladed tail for 550/600 size: H55T005xx. I have not been able to find any information on the size of the tail shaft for the Align 550, I'm hoping it's 5mm, which would hopefully make it an easier option to adapt to our Logos.

The SAB 3 bladed tail (H0429BM-S ) is made for the Goblin 630/700/770, so I haven't researched further but I suspect it's a 6mm tail shaft.



Edited 1 time(s). Last edit at 08/05/2019 04:12PM by HelisRock!.

Yes, the Align 550/600 one is for a 5mm shaft. I found the bearing sizes for the tail shaft in the manual. For $69 delivered from amain, I'm willing to give it a shot (and a $5 off coupon too!). It looks like I can use a ball in place of the forked pitch slider that Align uses. It will be here Thursday.

I looked at the SAB option and yes, it is for 6mm.

Excellent, let me know if you get it to work, I'll follow your lead

The item has arrived and the last few hours have been very educational.

The good: it fits on the shaft.

The not so good: The bearing holder (square piece the bellcrank arm attaches to) is tapped for 2.5mm threads, but the normal 4.8mm ball is setup for 2mm. Trying to tap a new hole in aluminum is a real pain in the rear. The case is too thin to tolerate any mistakes (really easy to strip the threads) but I believe I've found a way around this.

WARNING!!! If you feel brave enough to try a tap 2mm threads in the bearing holder, you have to remove the sleeve that's sandwiched between the 2 bearings. You only need to remove 1 bearing, but they are easily damaged during removal (crushed a shield on mine). You might want to order a couple of spare bearings if you go this route (MR117 7x11x3).

Possible solution: I found a 4.8mm ball with a 2.5mm hole at eastcoastvario.com. The part number is 107/43. This will allow me to use the existing holes and avoid the drill-tap-strip fiasco.

Some things to understand:
- The Vario 4.8mm balls are "slightly" smaller than the Mikado 4.8mm balls. The calipers show 4.80mm vs 4.82mm on the ones I have.

- I run my Logo rotor heads CCW (left-hand rotation) with the tail on the left side, and already have a Vario pitch lever installed that fits the Vario balls perfectly. A Mikado pitch lever will still work with a Vario ball, but a Vario pitch lever is just a little too tight on a Mikado ball.

- To use a Vario pitch lever, (assuming normal tail position on the right side) you need part numbers:
-- 97/10 Bellcrank (to flip the tail to the left side, use 97/30, all other parts are the same)
-- 97/17 Bushing for bellcrank
-- 90810 washer 3x5x0.5 goes between bellcrank top bearing and the mount point on the heli. Check your parts bin before getting this. It's just a spacer for the top bearing
-- 2 x flanged bearings (3x7x3) get from Bocabearing (99MF73) or RCBearing.com (MF683) to sandwich the bushing.
-- 4.8mm ball (2mm hole = 107/42 : 2.5mm hole = 107/43) to replace the Mikado one.
-- I added a normal 3mm nut and washer to get the right depth for the cup to grip the ball on a normal Mikado tail slider.
-- You may need a longer M3 bolt to attach the Vario bellcrank arm to the Mikado pivot point. Mine is 20mm.

Bottom line: It looks like this will work once I have the balls that have a 2.5mm hole. I've ordered those already. I'm going to try and salvage the bearing holder I have, but put the odds of that around 50%. A replacement for the damaged bearing is also on the way.

If I'm lucky, it will all be here Monday or Tuesday.

The adventure continues . . .

It's installed. I put it on my Logo 600SE, replacing the 2 x 105mm tail blades and rotor assembly.

I used a M2.5x6mm screw with one washer to attach the 4.8mm ball. After installation, I had to adjust the tail pushrod out about 5 turns to get the thing to center on the tail shaft. One issue I didn't anticipate was that the normal Mikado 85mm plastic tail blades didn't quite fit in the blade grips. The blade root was too long, but a sander took care of that. All blades weigh the same to the nearest 0.1g. The pitch slider fits pretty well, no slop in the bellcrank linkages, and moves freely along the shaft. It looks like it will work. I should be able to spool it up this weekend.

If all goes well, I'll order some 92mm blades and move it to the scale bird.

It went well! 3x 85mm blades held just as well as the original 2x 105mm ones. My main blades are 690mm, so plenty of torque to counteract. I had to increase the vbar's collective pre-compensation to keep the tail straight on full power climbouts, but the tail optimizer ended up with the same settings as the original tail. No issues with pirouettes, fast backwards flight or aerobatics (Full disclosure: I'm not a 3D pilot).

Bottom line: If 3 blades this small can do the job, I should be able to drop the head speed some more and have the tail still hold, especially if I use normal size blades. Now to move it to the scale heli.

Hi Gfyss,

Excellent work, great to hear it went well!

I'll have to order up the parts and do the same thing. So just a thin washer under the ball to space it out slightly?

I'll probably just use the Align 3 blade set, as they're designed for the grips.

What headspeed was your test?

Yes, just a normal 2.5mm washer under the ball got it in the right spot.

The test heli is running around 1400 rpm.

I just ordered some KBDD 96mm blades for the scale bird, which is currently at 1250 rpm (swinging 4x 620mm blades).

Well done - it is no rocket science at all - sometimes you just have to try ...

regards (EN) / Gruss (DE)

Rainer Vetter

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
Posting and answering - please use a PC and a standard keyboard. Answer all questions fully, take the needed time, don't forget probably requested attachments.

Für Posts und Antworten bitte einen PC und eine richtige Taststaur benutzen sowie alle Fragen vollständig abarbeiten. Nehmt Euch Zeit, beantwortet Rückfragen in Ruhe und vollständig.
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Glad to find this thread, I am ordering the Align 3 blade tail and have drilled out a couple balls on the lathe already so I should be set upon arrival of the tail assembly. Mikado , you should make 3 blade option for us lower headspeed and scale Logo flyers