RunRyder RC
WATCH
 6 pages [ <<    <     1     ( 2 )     3      4     NEXT    >> ] 16222 views POST REPLY
HomeScaleAircraftScale HeliScale Helicopter Main Discussion Docs  Gazelle Build
06-12-2013 03:08 AM  5 years agoPost 21
Joel Rosenzweig

rrVeteran

Marlborough, MA - USA

My Posts: All  Forum  Topic

Jim,

The TF Model mechanics use a 119T main gear.

Anyone,

For the next phase of my build, I hooked up the tail servo so I could put a load on the fenestron. I wanted to measure the power consumption so I could size a LiPo for the tail, and understand how long it would run.

For those who don't know, the tail is run from a separate LiPo than the main motor.

In any event, the power draw was only 170 watts at maximum deflection, 10.0A on 4S. It blew air, but it wasn't as much air as I thought it should be making. I can only compare it against my Vario EC-135 fenestron which made significantly more thrust.

I'd like to make sure that this is developing the desired thrust. Does anyone know how much power their fenestron motor is consuming on either their Gazelle or Blue Thunder? I'd like to know if it's similar to mine.

Thanks,
Joel

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
06-19-2013 06:15 PM  5 years agoPost 22
Joel Rosenzweig

rrVeteran

Marlborough, MA - USA

My Posts: All  Forum  Topic

Fenestron motor
I received feedback from Willis at TFModel who told me that the amp draw was too low. It's not clear why. He suspects the motor so he sent me a replacement. It looks like they are tooling up to use different motors now, because he is sending me a motor that runs on 6s instead of 4s.

Willis expects the motor to draw in the neighborhood of 550 to 800 watts. It's far more power than what my motor is drawing right now so this replacement promises to be very different.

I will set it up, take some measurements and observe the air flow. Hopefully that does the trick.

I am a little concerned that the tail belt is in the narrow side to carry that much power, but it's only intuition, not engineering. So I will run it for a few packs and see what it does.

The motor will be here in a few days. It just passed through customs in New York this morning. I am excited to try it out.

Joel

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
06-29-2013 11:25 AM  5 years agoPost 23
heliadictaholic

rrApprentice

Hobart, Tasmania - Australia

My Posts: All  Forum  Topic

G'day Joel,
I received my gazelle yesterday - I got the blue and white striped version.
I have a Blue Thunder, so I went for something a bit brighter this time. (still haven't had the BT in the air yet)

The mounting of the boom is a bit different to the blue thunder. Can you tell me how you fixed your boom to the fuse. I was going to epoxy as well fibreglassing on the inside.

Talking about the motor, I think the motor that I received is the same as the one in my BT - which I upgraded to a Scorpion HK-3226-900KV. I upgraded purely because someone else had problems with the tail when they ran 700 blades - I have 700 blades also. I also fitted a slightly wider belt and strengthened the motor mount so that it did not distort the bracket. I had problems with the belt jumping teeth as it rode up the side of the motor pulley.

Anyway, interested to hear how you get on with your tail drive.

If you could tell me how you went about fixing the boom to the fuse, would be appreciated.

Jim

PM  EMAIL  GALLERY  Attn:RR  Quote
06-29-2013 01:13 PM  5 years agoPost 24
Joel Rosenzweig

rrVeteran

Marlborough, MA - USA

My Posts: All  Forum  Topic

Tail
Jim,

I used Hysol to glue the tail. Then I applied several layers of carbon fiber cloth on the joint in different dirextions. I did some layers lengthwise and others around the circumference of the seam. It made a significant strength improvement.

Joel

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
07-07-2013 05:41 PM  5 years agoPost 25
Joel Rosenzweig

rrVeteran

Marlborough, MA - USA

My Posts: All  Forum  Topic

Fenestron Power
My kit came with a 9T tail motor pinion. At full pitch, the fenestron was only pulling a maximum of 150-170 watts. I learned that the Blue Thunder kit has an 11T pinion on the tail motor. This difference in pinion would account for a 22% difference in speed, and some unknown difference in power consumption.

I installed an 11T motor pinion, and then power consumption went up to 400 watts at full deflection (right yaw). This wasn't the 600 watts that I heard of on the Blue Thunder, but it was still considerably more power than the 150-170 watts I was getting before.

The problem wasn't solved though, because at this higher RPM, the fenestron mechanism was binding when attempting to input the more extreme pitch angles. I wasn't able to obtain full deflection under load. By using a wrench on the fenestron bell crank, I could see the watts go up to 400, but the servo could not push against this. I am using a JR DS8311 which 125oz/in torque at 4.8v. This is PLENTY strong for this application.

The TF Model factory sent me a replacement fenestron to try, along with the 11T pinion. So after seeing the change that occurred with just the pinion alone, I replaced the entire fenestron unit. That was surprisingly easy and took just 5 minutes to remove and install both units.

With the new fenestron installed, everything moved smoothly under load, and the servo was able to obtain full deflection while the fenestron was running. I then measured the same 400 watts. So far, so good.

So I decided that even though it wasn't 600 watts, I'd test fly and see if the tail would hold. Unlike my tests with the previous fenestron and gearing, this new setup worked properly. The heli and good yaw control and lifted off without incident. I was able to have good yaw rates both left and right (right is the one that counts!)

I flew two flights, each 9 minutes and the fenestron was OK. There were a few turns in the wind that the fenestron was not able to counteract. Most of the time, the tail was great, but from time to time, it couldn't handle it perfectly.

Now that I've run the fenestron, I have some data for anyone else who is interested:

9 minutes of flight on my 6S battery consumed between 1300 and 1500 mAH. It was approximately 30% of my 6s 5000mAH tail battery. The current consumption was between 8.7 and 10.0A average depending on the flight, and the average watts ranged from 193 to 222.

The 6S 5000mah is good for 2 x 9 minute flights with some reserve (i.e. there was 40% left in the battery after 18 minutes)

I have not adjusted fenestron speed via the governor yet. It's currently set to 80%. And, I have not really played with the tail gyro gains. It is possible that by adjusting the speed of the fenestron a bit, and by increasing the gains, I may get enough tail authority to lock the tail a little better in the wind.

All in all, it's working well. It does require a little more adjusting to see if I can make the fenestron feel perfect. I'm hopeful that I can do that.

Now that the machine is flyable, I am going to install the doors and windshield!

Joel

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
07-07-2013 07:53 PM  5 years agoPost 26
Dr.Tim

rrElite Veteran

Mojave Desert

My Posts: All  Forum  Topic

Joel, My tests here on the bench showed 11K speed at the tail (Blue Thunder) 90% on the esc that might account for the 600wt that I am showing at full deflection. I have not checked but willing to bet I am running around 400 to 500 nominal. My main gear is in route, so once it arrives I will get back on the build ..

From Simple minds come simple ideas! Approach Engineering

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
07-07-2013 08:05 PM  5 years agoPost 27
Mojave

rrElite Veteran

Palos Verdes, Ca. USA

My Posts: All  Forum  Topic

Sounds like you are on the right track with the tail. This is great info, thanks for sharing! I may want to build this heli at some time down the road. It's good to be able to go into the project with both eyes wide open and knowing what the obstacles are.
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

PM  EMAIL  GALLERY  Attn:RR  Quote
07-08-2013 03:27 PM  5 years agoPost 28
Phoenix NOTAR

rrApprentice

Tallahassee, Florida USA

My Posts: All  Forum  Topic

Joel,

If the fenestron is anything like the NOTAR's, then weight plays a very big factor in the performance equation. Could you use a 6S 2500mAh battery for the tail instead of the 5000mAh pack, and reduce the overall weight of the heli? You would need to charge/replace this pack every flight as you do the main power packs, but it may improve the tail performance.

Sandy

PM  EMAIL  GALLERY  Attn:RR  Quote
07-08-2013 04:00 PM  5 years agoPost 29
Joel Rosenzweig

rrVeteran

Marlborough, MA - USA

My Posts: All  Forum  Topic

Using a smaller tail battery pack
Hi Sandy,

I could use a smaller battery for the tail to save weight, as you suggest. That said, I'm using this large battery as ballast, because the machine is otherwise tail heavy. Despite adding such a large battery for the tail north of the main shaft, I still had to add weight into the nose of the machine to balance it out. So when I reduce the battery size, I'll still have to add some weight into the nose to balance it out again.

Your idea would help it achieve a total weight that is lower than it is now. The total weight savings of the battery itself is approximately 400g, compared with the larger battery. Therefore, the final weight savings would be something less than 400g after I add some ballast back.

I am also thinking about experimenting with reducing head speed. I'm running the head at 1350 with 700mm blades. I could try dropping it to 1200 to see how it feels. That would reduce the torque loading, which would help the tail, too.

The heli feels so good right now in all other respects, that I hope that reduced head speed doesn't significantly deterioriate that!

Joel

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
07-09-2013 09:42 PM  5 years agoPost 30
Joel Rosenzweig

rrVeteran

Marlborough, MA - USA

My Posts: All  Forum  Topic

Windows and doors installed - Nears completion!
I installed the windows and doors. Then I mounted the turbine housing and the drive shaft with standoffs. I added some vinyl decals, and the machine nears completion.

I have to decide what sort of door handles to add so that the doors operate. The kit doesn't come with any door handles, nor any mechanism to keep the doors closed. I have some Vario parts on hand that I might use, or I might go shopping to see what else is appropriate. I don't need anything elaborate, but something simple enough to allow me to keep the doors closed during flight. I am thinking of adding mock door handles (that won't rotate) and then using magnets to hold each door closed. This might work, but sometimes, stuff with magnets fly apart despite our best efforts to keep them locked down, and that doesn't always end well.

I am using the RC Aerodyne rotor blades from the Super Scale AS-350, which are 700mm blades. They fly really well on this machine (and the AS-350 too). They are currently painted white with red stripes as they come from the factory. I am thinking about painting them flat black or some shade of camo green. It appears that the full size has green blades that don't exactly match the body colors. So if I mismatch the color, it should be correct, right? :-)

I flew the heli in my yard after taking these photos. It's is really smooth and stable and the fenestron sounds really different. I like it.










PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
07-09-2013 10:36 PM  5 years agoPost 31
Keygrigger

rrVeteran

Mississauga, Ont. Canada

My Posts: All  Forum  Topic

Nice work so far. There is something about multi-blade helicopters where they seem to fly so much more stable and smooth and the more blades, the merrier. Take care.

Don

PM  EMAIL  GALLERY  Attn:RR  Quote
07-10-2013 01:26 AM  5 years agoPost 32
Mojave

rrElite Veteran

Palos Verdes, Ca. USA

My Posts: All  Forum  Topic

Any idea when Cliff will be offering these blades by themselves? I like the look of the square cut tips. What profile are they?
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

PM  EMAIL  GALLERY  Attn:RR  Quote
07-10-2013 02:51 AM  5 years agoPost 33
Joel Rosenzweig

rrVeteran

Marlborough, MA - USA

My Posts: All  Forum  Topic

Barry,

I don't know what the name of the airfoil is, but it looks like this:

I asked Cliff for these blades, and he had them available. I don't know if they are on the web site or not, but you could just call him and ask him about ordering a set. That's what I did. The awesome part is that they are a matched set. I really like that. I got tired of balancing blades when working on my Chinook, so this was a treat. :-)

Joel

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
07-17-2013 07:26 AM  5 years agoPost 34
Joel Rosenzweig

rrVeteran

Marlborough, MA - USA

My Posts: All  Forum  Topic

I flew the Gazelle at my local field this weekend to see how the fenestron would do. I thought it was working OK while in my back yard, but, on occasion, the tail would stall and I'd lose the ability to yaw right.

I tried a variety of experiments to improve this, but still have not quite resolved the issue.

First, I tried changing the rotor blades from the semi-symmetrical blades to some symmetrical blades. The theory was that it would reduce the torque and make it easier for the tail. That didn't do it.

Then I tried increasing the rotor RPM from 1350 to 1500 to see if the torque would decrease. It wasn't measurably different.

Then I tried reversing the rotation of the rotor head to see if the extra power consumption I measure on full left yaw compared with right (400 watts vs. 310 watts) would translate into more available yaw when needed. So I converted the mechanics and tried again. Unfortunately, there was no difference. If anything, it was slightly worse.

Then I decided to try the heli with a 2-bladed flybarless head. I assumed that would really lower the torque, and would make this fly well. So I took a Vario Skyfox head, removed the flybar, grafted it to this machine, with a Vario swash plate and follower, made some new rods, and made a doubler for the anti-rotation bracket so that the smaller Vario swash would fit. This was going to work great, right? Well, no. It wasn't really any better. Perhaps having the machine as a left hand rotation machine wasn't such a good idea. I thought it was worth a test, and it certainly made it easier to try the Vario head on this machine, and I had the symmetrical blades to try with. But, it just didn't work better. The power consumption went from 20.5A to 17A when going from the 3-bladed head to the 2-bladed head. It was certainly using less power, but this just didn't translate into enough difference at the tail.

This video from Sunday, shows the 3-bladed Plug N Play head, with some 690mm symmetrical blades, right hand rotation. It was maneuverable, but the tail was stalling on me when exiting turns. You can observe that a little bit in the video. I didn't annotate it though.

Watch at YouTube

While doing the 2-bladed head test, I had a hard landing after losing the tail. This bent the landing gear up a bit, which then cracked the body around the gear tubes. :-( Now I am not quite sure what to do.

Joel

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
07-17-2013 10:00 AM  5 years agoPost 35
heliadictaholic

rrApprentice

Hobart, Tasmania - Australia

My Posts: All  Forum  Topic

G'day Joel,
I don't know if this link and details below are of any help. The heli on the youtube clip is a 700 Blue Thunder but has the same fenestron as the Gazelle. Might be worth talking to "fischer859" - he may be able to provide some of his Blue Thunder setup experience - might help. What fenestron RPM are you running?

Watch at YouTube

Hope "fischer859" does not mind me putting his details here.

His Blue Thunder setup below:

Published on Aug 10, 2012
Blue Thunder RC Helikopter 700 3-Blatt,
Mechanik: T-Rex
Hauptmotor: ScorpionV3 550KV, Ritzel 10Z, HZR 115Z Modul1
Akku: 8S 5800mAh
Heckmotor: Scorpion 880KV Fenestron-Riemenantrieb 11.000U/min
Akku: 4S 5000mAh
Rotorblätter: Spinblades 3-Blatt Satz 700mm
Kopfdrehzahl: 1400U/min
Abfluggewicht: 8,2Kg
Servos TS: 3x Align DS620
HeckFen: Futaba BLS 155MG (18Kg)
Flugzeit: ca: 15min

PM  EMAIL  GALLERY  Attn:RR  Quote
07-17-2013 12:11 PM  5 years agoPost 36
garyl

rrVeteran

taxachussetts

My Posts: All  Forum  Topic

Do a bench test on the tail using a strobe light so you can see what is going on with the tail blades and if you are getting full deflection under dynamic load. I have a nice strobe light if you need it.

PM  EMAIL  GALLERY  Attn:RR  Quote
07-17-2013 01:27 PM  5 years agoPost 37
Mojave

rrElite Veteran

Palos Verdes, Ca. USA

My Posts: All  Forum  Topic

Hi Joel, sorry to hear about the mishap. I'm sure you'll have her up and flying soon. Just a thought, but you may want to run a higher TQ servo on that tail and see if it helps. You may not be getting full deflection. I took some advice from Stan and a few others in here and started using a BLS451 on the tail of my larger helis and it works great.

Thanks for the blade info. BTW that's a Clark "S" airfoil and it produces a ton of lift.
Barry

All helis and planes have an expiration date stamped on them...you only find it after you crash!!

PM  EMAIL  GALLERY  Attn:RR  Quote
07-19-2013 05:53 AM  5 years agoPost 38
Joel Rosenzweig

rrVeteran

Marlborough, MA - USA

My Posts: All  Forum  Topic

Fenestron RPM
Jim,

The fenestron RPM is approximately 10,200. I am only able to calculate this value based on motor kV, volts, gear ratios, and ESC setting. I haven't put it on a tachometer to verify.

I am going to install a motor with higher kV that will let me experiment with 11K, 11.5K, 12K, 12.5K and 13K RPM as necessary. I'll bump it up in 500 RPM increments, and observe what it does. If it starts to hold at a particular RPM, then I'll keep it there. I'm also going to install a Castle ESC with logging and governor control to help me get very accurate data on the tail setup. I'll be able to log fenestron watts and RPM, and set the RPM easily, too. That will take some guess work out of it.

My parts should arrive by Saturday, so weather permitting, I'll give the machine more tests this weekend and I'll report back on what it does.

As of tonight, I converted the mechanics back to right hand rotation, and reconfigured the Naza again for these changes.

Joel

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
07-19-2013 06:01 AM  5 years agoPost 39
heliadictaholic

rrApprentice

Hobart, Tasmania - Australia

My Posts: All  Forum  Topic

G'day Joel,
Do you know the KV of the stock motor that comes with the kit? I am getting a collection of them. I have 3 fenestrons - all going to Scorpions and CC ESC's. changed one so far - I will wait for a while before I upgrade any more.

Jim

PM  EMAIL  GALLERY  Attn:RR  Quote
07-25-2013 04:20 AM  5 years agoPost 40
heliadictaholic

rrApprentice

Hobart, Tasmania - Australia

My Posts: All  Forum  Topic

G'day Joel,
How are things going with you?

I have assembled my TFModel mechanics for my Gazelle. One thing I am not too happy with is that there are no thrust races on the main shaft. All the weight of the heli is carried on 1 radial bearing - the bottom bearing. This is a standard radial bearing which can not take a lot of axial load. To help the situation, you can put a locking collar under the top bearing - it will fit (make sure it does not contact the outer ring of the bearing), then the weight of the heli will be carried on both the top and bottom bearings providing a bit more support and splitting the load over the 2 bearings.

I went one step further. I replaced the slip on collar that is located directly under the bottom bearing, with a thrust race. I made a special holder for the thrust race. Have a look at the photo (sorry I didn't realise it was so fuzzy but I think you will get the idea.)

I don't know why manufacturers do not incorporate thrust races on the main shaft - especially on heavy helis. I would not like my heavy 8.5kg Blue Thunder relying on a radial bearing to carry axial load. I am using KDEDirect bearings and mounting blocks on my BlueThunder. The KDEDirect bearing blocks have 2 thrust races on the main shaft.

Anyway, hopefully your updates are going well and will solve the tail problems...

Bearing reference data:http://www.bocabearings.com/dropin....on-Write-Up.txt

Jim

PM  EMAIL  GALLERY  Attn:RR  Quote
WATCH
 6 pages [ <<    <     1     ( 2 )     3      4     NEXT    >> ] 16222 views POST REPLY
HomeScaleAircraftScale HeliScale Helicopter Main Discussion Docs  Gazelle Build
 Print TOPIC  Make Suggestion 

 12  Topic Subscribe

Saturday, November 17 - 2:15 am - Copyright © 2000-2018 RunRyder   EMAILEnable Cookies

The RC discussion world needs to consolidate. RR is now one choice for that. Its software is cutting edge. It hosts on-topic advertising. Help RR increase traffic buy making suggestions, posting in RR's new areas (sites) and by spreading the word.

The RunRyder Difference

• Category system to allow Rep/Vendor postings.
• Classifieds with sold (hidden) category.
• Classifieds with separate view new.
• Answer PMs offsite via email reply.
• Member gallery photos with advanced scripting.
• Gallery photo viewer integrated into postings.
• Highly refined search with advanced back end.
• Hosts its own high end fast response servers.
• Hosts thousands of HD event coverage videos.
• Rewrote entire code base with latest technology.
• No off-topic (annoying) click bait advertising.
Login Here
 New Subscriptions 
 Buddies Online