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Scratch-built Telemaster


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#1 mieczotronix

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Posted 19 June 2008 - 04:31 AM

Hi. Having read all the good stuff about weight-carrying capacity of Telemaster I decided to build one myself. I ordered a kit from HL USA. This involved some hassle, as I had to use a third party shipping company to carry the oversized box by sea to me. After two months of expectations the kit arrived and I've started building my Electro Telemaster (HL kit - 180 cm wingspan) from scratch. I wanted to build a kit so I could easily adapt it to carry my payload.
At the moment it is an Ixus, a small cam on pandora pan&tilt + some more stuff like eagletree data recorder, hexpert zlog ,some of my electronics and possibly many more in future. I plan to build the plane with the following features:
- flaps
- AXI 2826/12 (I already have it).
- split wings (I don't know yet what to make the bayonet mount of - I got a spare, bent 450heli boom made of some aircraft grade alu - very stiff 13 mm inner diameter - don't know if it is gonna be of any use for it)
- put tail & rudder servos somewhere in the tail section (possibly inside the fuselage under a hatch) to free space near COG
- lots of hatches and compartments to hide stuff like electronics, batteries, connectors, switches, indicator LEDs ...
- compartments in left and right wingtips for vid tx and gps

I've been just finishing the fuselage framework and since I want to build in it those various facilities, I need some input from you. Here are my questions:

1. Where exactly you put your lipos in yuor ETMs (what kind of 3300/4000 mAh 3s/4s)? i.e. how far from the firewall (1st bulkhead). I haven't ordered lipos yet. I have some 2200 mAh 3s packs. And I was planning to buy two more and use them in parallel in ETM and separately in my other smaller models.
2. I've been planning to use a small li-po pack instead of BEC. Should I use one for servos + video stuff or 2 separate. What do you suggest?
3. What size of wheels would be right for very rough terrain (tall grass) - will 100 mm foam wheel be any good?
4. Would you recoomend HS-81 / 82 (mg) or standard cheapos hs-322 servos?
5. Should I go for detachable rudder or stabilizer ?
6. I plan to install a mount for pan serwo in the bottom of the fuselage in front of wheels and possibly under a wing (how far from the fuselage you have your underwing cams)
I guess that's it for now. Expect more questions as I progress with the build. Of course feel free to post your other suggestions of what I could improve, build-in in the model.

regards
Chris

#2 Mr.RC-Cam

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Posted 19 June 2008 - 10:08 AM

There are many flavours of Telemasters, so the details will be different for each. I can only relate to the Hobby Lobby's 6' ETM ARF version.

1. Where exactly you put your lipos in your ETMs (what kind of 3300/4000 mAh 3s/4s)?

Mine balances with a 5-cell A123 pack pushed tightly against the motor firewall. I also have the brushless motor on 1" standoffs, with heavy tires, all of which helps out. I have two HS-81's near the tail, so it may be different for you if you put the Rud/Elev servos elsewhere.

2. I've been planning to use a small li-po pack instead of BEC. Should I use one for servos + video stuff or 2 separate. What do you suggest?

It's up to you. Personally, I don't like sharing the servo power with video gear. This reduces the RF paths and helps minimize the possibility of conductive RFI noise issues. On a big model like the Telemaster, there is no need to save weight by sharing the battery.

3. What size of wheels would be right for very rough terrain (tall grass) - will 100 mm foam wheel be any good?

I'm using 3.5" balloon tires. I wish mine were bigger.

4. Would you recommend HS-81 / 82 (mg) or standard cheapos hs-322 servos?

I'm using two HS-81MG's on Rud/Elev and four HS225BB's on flaps/ailerons.

5. Should I go for detachable rudder or stabilizer ?

I didn't have any need to do that.

6. I plan to install a mount for pan servo in the bottom of the fuselage in front of wheels and possibly under a wing (how far from the fuselage you have your underwing cams)

To make the wing balance, I placed the video Tx on the opposite wing tip. Then found the location on the other wing panel where the camera allowed the wing to balance. This trick allowed me to avoid adding wing weights to balance it out.

BTW, there's a couple other discussions around here that talk about the ETM. Plus, rcgroups has good Telemaster discussions too.
- Thomas

#3 mieczotronix

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Posted 19 June 2008 - 11:18 AM

Thanks.

I can only relate to the Hobby Lobby's 6' ETM ARF version.

That's the one I've been building, except its kit rather than ARF.

So from what you've been saying it is tail heavy, right? So maybe I should thin it out a little by building framework rudder and tail rather than solid one? Should I really try to lighten it up at rear or that is not as much important and I will balance it somehow.

I'm using 3.5" balloon tires. I wish mine were bigger.

How much bigger? Since I have to order a pair anyway, maybe I go straight for the biggies?

I think I did read all posts about Telemaster Electro here and on rcgroups. But it seems like everyone got ARF version.

Thanks for other pointers, very valuable.

#4 Mr.RC-Cam

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Posted 19 June 2008 - 11:32 AM

That's the one I've been building, except its kit rather than ARF.

Although they look the same on the air strip, I've heard that there are slight build differences. For example, I think the kit is setup for glow or electric, whereas the ARF is only electric. This might change where things can be positioned in the nose area.

Should I really try to lighten it up at rear or that is not as much important and I will balance it somehow.

If the balsa they provided is light stuff, then I would recommend building to the plans. Otherwise, do what seems best to you.

How much bigger? Since I have to order a pair anyway, maybe I go straight for the biggies?

As big as you can accommodate. The weight can become an issue and big tires weigh a lot.
- Thomas

#5 Wavess

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Posted 19 June 2008 - 01:26 PM

I donīt think itīs necessary to lighten the tail section, if you look at the elevator surface itīs ligthen enough to do well. Wouldnīt go with other option than planīs instructions. And you would notice that the heavy tail is going to help you to balance the model if you want to put big batteries on it. Personally Iīm using a 4S 3200mah and 4100mah packs, but I would go soon to 2x3200 mah in parallel.
I purchased big tires too, 90cm (very close to 3.5") because my flying field is abrupted. But after weighting them I did realize that there was a big difference in weight with the stock ones. So I made a try with stocks and they work very good till now. Iīd suggest you try the stock ones, and if they donīt work for you change them. You could always buy them after at you LHS, they are easily found there
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#6 mieczotronix

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Posted 22 June 2008 - 10:10 AM

Ok. Thanks for your suggestions.
I am now preparing to buy some gear.
Tell me what do you think about this

1) Kavan (German) 125 mm inflatable tyres (that's almost 5")
2) Carbon landing gear: width 390 mm (15") / height 185 mm (7")
3) HS 225BB for ailerons (fast)
4) HS322HD for flaps (can be slow -> low current draw)
5) HS82MG for rudder & elev (fast, powerful and heavy-duty)
6) 38mm (1.5") tail wheel with some kind of alu brace for attaching it to the fuselage
7) 6mm (4 1/4") carbon rod + 7/6.22 mm brass pipe - for bayonet mount for wing + 8mm plywood for wing mount
8) 5000 mAh 25 C 4s1p LiPo - 46 x 50 x 144 mm and 660g (23 oz) weight - will I be able to easily balance the plane assuming the battery will go in between bulkhead #1 and #2? The space between bulkheads #2 and #3 will be the cargo bay, where I will put my ixus or another payload. I installed a floor inside it, to which I will suspend the camera on velcro. Above the floor I have room for electronics and BEC batteries (I can even fit 2200 mah 3s lipos there).
Another option I've been considering battery-wise is to buy 2x 2200 mAh 3s1p (rather than 4s), which I could use in my heli.

What do you think about that?

#7 mieczotronix

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Posted 26 June 2008 - 11:37 AM

Ok, I bought the gear I asked 'bout in the previous post.

Here's how it looks on the fuse
Posted Image
Posted Image
kind of funny looking, but I hope it will perform well on tall grass
the landing gear and wheels are very light, it's not noticeably heavier than stock lg with 2 3/4 " wheels.
I've also bought a clever tailgear with built in servo saver (those springs)
Posted Image
I'll cut away some balsa from the fuse, put 8mm plywood instead and fix the tailgear to that.