DONE! Stretched Trex Helicam

[j_kookboy]

Originally Posted by Wbird

OK Bullaculla, I'm Jealous.

Nice setup. Have you thought of doing flybarless on this rig. A friend of mine has a couple of Logo 600's now with V-Bar. We were looking at his flight times and battery capacities. If I stretched one of them to 690s and run it around 1800 or so we could possibly get 15 minutes on a 10 cell 5000 mah pack. Those helis are very efficient.

Here's mine in the stock size. Would you recommend I stretch one or exchange for a flybarless logo and stretch that, AP use?

I wouldn't recommend to run 690's on the align head at 1800. You'd be pushing the limits.

690's on that head should be spinning at 1500-1600 for AP flight.

As a comparison, I blew the head apart in mid-air on my backup raven at 1760 with 690's. I switched over to a metal head, lowered the RPM's down to 1500 and found the sweet spot for efficiency/AP.

Just a suggestion.

Jesse

[jascamera]

Guys,

For those who are short on money and don't want to do all the work to strecth the t-rex. Try a front mount setup, you will lose close to 2 pound of weight. When I first got the 360 underslung from Askman, I had couple of test flight and sent it right back because of the weight. Askman also have a front mount, but I modify my own front mount, cost me $150, then payign $400. Total weight is about 10 pounds with a 19 oz HD video camera, have a lot of climbing power with stock 600 XL motor and 4200 mah battery for about 5 minute of flight time.

Most people will argue the unslug are better to isolate vibration, for those who use for aerial still photos, there nothing to worry about because you can get away with it by with a faster shutter speed, higher ISO. In fact, switching from underslug to front mount, the photos quality was never a problem. It gets challenging when you use it for video. But look around and you will notice all the pro video people are all using front mount over underslug. Front mount also serve are a gauge for how well tune your heli is. If you are able to get good video with front mount, meaning your heli is tune perfectly, meaning less vibration, less part failure and less crashes.

With front mount, the 600 fly normal, you won't get the pendulum effect.

Also the 600 is design to swing a 600mm blade, with a 700mm blade, even the head and tail unit are strong enough, the ball link are the parts that I worry about, it might not be up to this type of stress for long run. Need to do a lot of testing.

All in all, I would skip the Underslung mount setup--just too heavy and the benefit just don't justify for the negative that it comes with.

[bullaculla]

Thanks for the safety concern. I am flying well under 1800rpm, and I am using a full metal head, and grips with a custom titainum spindle shaft. I am testing it eveyday with partial teardowns to check on wear. I am having problems with my tail tho. But I think its just the gyro settings that needs to be tweaked because of the huge tail blades. I just got back from the field after about 45 minutes of air time, and now my heli is almost complety apart.
Also, there are a few people who fly stretched trexs with 700mm blades doing hard 3D. One guy has been flying his for over a year without any problems, so I am not worried

Jascamera, I know all about the front mount

[crewchief]

Originally Posted by bullaculla

Thanks for the safety concern. I am flying well under 1800rpm, and I am using a full metal head, and grips with a custom titainum spindle shaft.

What's the best tach/method for safely testing headspeed?

[Randallhurd]

I looked at the Maxi Joker2 and didn't see any prices..
Looks like the tail boom has a 45 on it.
Is that a pretty stable Heli? The web sites that I went to were pretty simple.

[bullaculla]

Originally Posted by crewchief

What's the best tach/method for safely testing headspeed?

Skytach!
http://www.espritmodel.com/index.asp...OD&ProdID=5849
X-cell makes one too, but its a little more expensive. But you need someone to tach it for you. The other way is the little cheapy handheld tachs, but those need to be within a few inches of the blades. You can hold it yourself with the heli on the ground, but you wont get actual HS in a hover. Or you can calculate it by your gearing and motor KV. Mine is pretty accurate. With my motor and gearing, max HS will be around 1800, and I tached it at 100% throttle and it was just under that figure. I usually run around 70-80%

Originally Posted by Randallhurd

I looked at the Maxi Joker2 and didn't see any prices..
Looks like the tail boom has a 45 on it.
Is that a pretty stable Heli? The web sites that I went to were pretty simple.

Maxi joker is very smooth, very strong (with the $500 blue pletti) and very stable, but isn't very agile with 800mm blades. The kit alone is $1300. plus another grand for just ESC and motor. Most guys run 10s 8000mAh lipos, and get around 10-20 minutes. The first gen Maxi-Joker came with the kick tail. They used it to keep the tail out of the long grass. They give a straight tail for the MJ2, but you can still get the elevated tail as an upgrade. Most guys dont run it cause its a little less inefficient, and is just another point of failure. Some good pics and info here:
http://www.espritmodel.com/index.asp...OD&ProdID=4748
https://www.fxaeromodels.com//produc...roducts_id=570
check out the reccomended motor and ESC!
Its pretty much industry standard for electric AP helis.

[crewchief]

Originally Posted by bullaculla

Skytach!
http://www.espritmodel.com/index.asp...OD&ProdID=5849
X-cell makes one too, but its a little more expensive. But you need someone to tach it for you. The other way is the little cheapy handheld tachs, but those need to be within a few inches of the blades. You can hold it yourself with the heli on the ground, but you wont get actual HS in a hover. Or you can calculate it by your gearing and motor KV. Mine is pretty accurate. With my motor and gearing, max HS will be around 1800, and I tached it at 100% throttle and it was just under that figure. I usually run around 70-80%

OK. Thanks!

[SFACV]

Bullaculla,

I am using the metal blade grips (wouldn't use the plastics on 600mm blades)LOL. Is there any problem with the align metal grips/bearings handling the 700mm blades? Is the titanium spindle needed or will the stock one handle the extra weight/force? In your opinion of course. LOL I am looking to do something in the 700 size for spring, nice to have a bit of input before going there. I am very interested in going flybarless as well. Thinking Helicommand rigid. Do you think the ball links on the swash and metal blade grips will be ok for the extra force on flybarless?

BTW thanks for sharing, you have an awesome looking machine.

[bullaculla]

I really have no idea how it will hold up, but I have about an hour on it now and everything seems solid besides the weird kick im getting from the tail.
Here is some good info I have found
This guy, PhilL also posts here, and he is the one that I got the custom boom from.
http://www.rotortips.net//index.php?...d=13&Itemid=32
https://www.helifreak.com/showthread.php?t=44796
http://www.rcgroups.com/forums/showthread.php?t=762506
So you guys see? stretching the trex is nothing new. If the stock head can handle 2000+rpm while doing 3D, i'm sure it can handle 1600-1700 carrying a little weight while hovering

[j_kookboy]

Yep.

I just wanted to point out that the higher HS is not really necessary for our type of flying/work. Kick it down a notch and you may find that sweet spot and gain a few mah's.

Every heli has it's sweet spot it looks like you're almost there.

Way to go Iven.

Jesse

[bullaculla]

:cool:

Originally Posted by trackhead

You're new heli is really making me want to build one myself. I don't really need the extra power, but it just looks fun.

When and if you have time, it would be cool to see a vid of the 700 flying.

Here is just a little test video from today. I'm limited to uploading <10mb.
Most of the flying was trying to get the gain right on my tail, and messing with the AP2000i
:cool:

:edit:
Opps, forgot to post the vid
http://photos.imageevent.com/bullacu...i/Untitled.wmv

[SFACV]

Looks good, how are you finding if for lift/stability compared to 600mm. Are you still running around 1800 rpm?

[Randallhurd]

That's a very Sweet Machine...
Definantly an inspiration point to shoot for.

[bullaculla]

It only needs a few degrees of pitch to hover. I actually lowered all my pitch settings. +/-10 degrees is enough. I found that with the 600mm blades, I needed to be a little over 3/4 stick to hover with a load. 620s were a little better, but pulled more amps. At 100% throttle is just under 1800. I am running the the gov at 75% and 80% so probably around 1650-1700. I gotta tach it again once I get my eagle tree RPM sensor hooked up. I have no one to help me skytach it. But at those throttle curves, it has plenty of power and is still very stable. Cant wait to get the nose mount on
Thanks for all the kind comments guys

[Efliernz]

Way to go Looking great. The pendulum effect must help the stability too.

[Piton]

Any idea when the Trex 700 will come out from Align?

Great thread BTW.

[bullaculla]

Originally Posted by Piton

Any idea when the Trex 700 will come out from Align?

Great thread BTW.

Hey Piton, Long time no see
I have no idea when, but probably about a year after the 500 comes out. But being a nitro, i'm not really interested. Maybe I can use a few parts if they fit. Right now, i'm looking for some sturdier boom supports. The longer ones I made flex too much and I had to double up on the braces.

[jgeorgic]

That is one sweet looking heli ! I bet it flies like a charm

Send us some warm weather

Happy Holidays

Jeff G.

[crewchief]

Originally Posted by bullaculla

Right now, i'm looking for some sturdier boom supports. The longer ones I made flex too much and I had to double up on the braces.

I was going through the spare parts for the Varios and I found some black CF tail boom supports. They're a couple of inches shorter than the ones that are currently installed, so they must have come off the original Trainers before they got stretched. If you'd like I can measure & take some pics of them. They might be about the right length.

[bullaculla]

That would be great! I was looking at the rappy .90 supports, but was surprised by how much they were.