Pre-production Twinn-Rexx build pictures

[Angelos]

You should run the gyros in normal mode (not Heading-Hold) when the AP-2000i is in charge.

-Angelos

[Gra55h0pper]

Hi Angelos,

Nice of you to pitch-in on this thread! Let me start by saying that your products ar world-class! I now have three helicopters, all of which are equipped with AP2000i stabilization and it works great. I normally fly with stabilization off, but in case of emergency, I flip a switch and the heli is level again. Many people say that's "cheating", but I guess those are the ones who enjoy crashing their helis and feel simulators are for woosies also... :mrgreen:

Let me try to understand your comment though. Just to make sure we're clear on this, my current setup for cyclic control is as follows:

- Rudder: receiver -> rudder gyro -> TH-2 (i.e. the tandem mixer) -> servos
- Elevator: receiver -> TH-2 -> servos
- Aileron: receiver -> AP2000i -> TH-2 -> servos
- Pitch (CP): receiver -> AP2000i -> TH-2 -> servos
- Differential (DCP): receiver -> AP2000i -> DCP gyro -> TH-2 -> servos

Here:
- The DCP channel is mixed in the TX to "slave" the elevator channel by 70%
- The rudder gyro is in normal mode (i.e. not heading hold/AVCS)
- The DCP gyro is in heading hold (AVCS on)
- Yaw compensation is enabled at 20% in the TH-2 to counter DCP-induced torque with rudder (I feel this is better than doing it in the transmitter as the TH-2 sees both the inputs from the gyro as well as from the AP2000i)

So when the AP2000i is in charge, it controls DCP, aileron and pitch but not elevator and (of course) rudder.

For the rudder gyro, I'd say whether to run heading hold or not is irrespective of whether the AP2000i is in charge or not (would you agree?).

For the DCP gyro, my reasoning was that as the gyro is "behind" the AP2000i, it "sees" whatever inputs the AP2000i is giving ("as if" it's the pilot giving the inputs from the transmitter) and can therefore be put in heading-hold or not-heading-hold mode without any "fighting" to occur (would you agree?).

Note that a disadvantage of this setup is that the AP2000i can only level the heli in the elevator plane by applying DCP as it doesn't control the elevator function. My ideal setup (just dreaming here :D ), would be to have the AP2000i control both elevator and DCP (at 70% of elevator) next to aileron and pitch, thus letting the servo4 output be DCP in a new swashplate mode for tandems... That would be so :glasses2:

The other setup (my original idea) I've considered is to let the AP2000i control elevator, with the gyro in the DCP channel. Thinking more about this, I guess for that setup I would have to run the DCP gyro in non-heading-hold to prevent the AP2000i and the gyro from fighting eachother. Possibly your comment referred to that setup?

Your inputs are much appreciated! You're definitely the guru in this world when it comes to flight stabilization! :mrgreen:

Hopper.

[blax1]

WOW!!!! A truly amazing thread, I've been following Joe's build info- on his site for the last two and bit years and I didn't realize there was a build thread here until he posted it on his site back the 8th of June, good luck to you hopper, a great build thread, and I love the flight stabilization equipment, many people are quick to knock these systems, but the time and money tied up in this sought of machinery can be exceptional, so if you can avert a disaster :shock: I say more power to you, great heli- I've bookmarked this thread and I will revisit to see how you are travelling :glasses2:
Cheers great stuff :D
Ralph
BTW-What type of radio are you using 72MHz or the new 2.4 GHz technology :?:

[LITHIUMSTATIC]

I would love to see a video of this thing flying!!!

[good2win22]

Hey Lith,

Here's a link from Joe's website.

http://www.tech-mp2.com/Twinn_Rexx/TW-1_LQ.wmv

[LITHIUMSTATIC]

Thanks!!!

[txflyer]

man that thing is sweet. the whole time i was watching i was waiting for a blade strike..kinds makes me want one.. this might be a stupid question but can that thing do inverted hovering. in the video it does look pretty responsive... what are its limitations..

[good2win22]

Gra55h0pper,

Haven't heard from you in while. Curious as to how the machine is doing.

Jason

[Gra55h0pper]

Good2win22,

The machine is doing great! Sorry I haven't posted in while, but I must have ~30 flights on it now. Just this past weekend, I flew it in pretty strong winds. Pretty amazing to see the 2 gyros and stabilizer work the cyclic on the two heads!

I'm sorry for those who would like to see a video, but I have no access to a camera. Besides, I'm not that good of a pilot... :roll: Also, please don't ask whether it'll do 3D, as I don't plan to find out if I can avoid it... I'll probably flip the stabilization switch well before that! :mrgreen:

Note that I decided to keep the setup as I described earlier (with respect to the gyro, ap2000i). When looking at some threads describing how to use the ap2000i as a virtual flybar on a "regular" heli, I realized that in that setup you don't have a choice but to put the gyro "in front of" the ap2000i as the ap2000i does the CCPM mixing. In that setup, I understand that it's better to have the gyro in non-AVCS mode. After the CCPM mixing is done, of course the opportunity to use a gyro to stabilize a single cyclic function (elevator, aileron) is gone...
On my Twinn-Rexx however, the CCPM mixing is done by the TH-2. This gives the opportunity to put the gyro "behind" the ap2000i. I think Angelos didn't realize this fact when replying to my earlier post. The way I look at it, is that the ap2000i is essentially a 2nd pilot which keeps an eye on the horizon. After this 2nd pilot adds its inputs, the DCP gyro (in AVCS mode) takes care of the rest.

I learned from Joe that the fuselages are getting ready (see the www.tech-mp.com site). I'll post more experiences when I have one! :glasses2: I understand one mod which is necessary is to move the rear elevator servo down in order to get it to fit in the fuse. Should not be a big problem though. I've decide to stick with the stabilizer. I'm not sure how exactly yet, but I really like having the option to stabilize the heli when the wind comes up. Also, having an "emergency leveling switch" is great when you loose orientation.

Hopper.

[chipbury]

Hi Hopper,
Great thread - i have been following the Tech Model Products website for a while now eagerly anticipating the day i can get one shipped to the UK.
I am shortly going to fit a three blade head to my spare T-Rex 450XL and see how i get on with it. If it works out ok i will think about using two of these on a Twinn-Rex. I hope to paint my fuselage in the British Airways colours that some of the long range passenger versions were painted in when flying to oil platforms in the North Sea.
Best Regards,
chipbury.

[medflight]

Any new updates on the twin rex?

[Gra55h0pper]

Hi Chipbury,

Having one with two three-bladed heads would be really cool!!! I also like the idea of painting it in a civilian color scheme when the body becomes available. I was considering doing so myself (looking at the Canadian one).

Hopper.

[leapfrog]

Hey h0pper!

It seems that we are both getting the flights in... that is fantastic! I'm currently in the middle of the motor trials that I promised, and am approaching the 50-flight mark. I'm gathering all sorts of emperical data, and looking into a few of the "traits" of this heli.

The most notable trait (data not necessary): It's just so much fun to fly... *big grin*

Nice one, Helimex! You should start a build thread for it - and keep us posted!

Leap

[melsman]

Hey Everyone,

I figured a 1:11 scale turbine CH-47 deserved a unique spot, so I gave Helimex his own build thread. I'm really looking forward to seeing more pictures and information on both of these builds!

Ashley

[kgfly]

And the Helimax build thread is here: http://www.helifreak.com/viewtopic.php?t=43089

[good2win22]

Hey hopper,

Here's a link to three bladed head that will fit a trex main shaft. Not bad for a hundred bucks.

Here's the link to the thread talking about it:
http://www.helifreak.com/viewtopic.php?t=42709

Here's the link to one of the seller's:
http://flying-hobby.com/catalog/product_info.php?cPath=3_27_53&products_id=1528&osCsid=4048807a94beecd0b59708dbd9375053
It appears that this guy has them back ordered so might look for another source.

[Kindling Maker]

Cool I love the Chithook, as long as I dont have to ride in one of those giant eggbeaters. I know that they are the fastest helo in the inventory, the most battle tested, and the most uncomfortable thing to ride in I have ever flown in. I had to fly in one last week. Just a bit of advise, dont get behind the idiot on crutches, by the time we finally got on I thought the skin on my fasce was going to boil off. and then we sat on the ground for 15 minutes defore we took off, no fun in full body armor.

[chinookmark]

Hey Kindling, I always tell my passengers to approach my 'Hook from 45 degrees off the ramp to avoid the 6000 HP worth of exhaust (unless it's winter lol!). It's a much more comfortable ride as a crewmember. Make friends with the flight engineer, and try to score the gunner's seat or a ramp ride. BTW, the easiest way to bribe a Hooker is by offering beer and bringing women. I'd stick with the beer, because the women will end up with the seats you were trying to score lol!

[Sherpa FE]

Women that heve been deployed??? yuck...tastes like baby wipes
:lol:
Thats why I like my Sherpa, I get the comfortable seats.
Currently deployed to Kuwait / Iraq

[chinookmark]

Women that heve been deployed??? yuck...tastes like baby wipes
:lol:


ROFL!

[Bond007]

Great info :)

I have just been in touch with Joe, and am hoping to have one winging its way to my house real soon :YeaBaby:

Any more info or updates since your last posts.

Any one tried a 3 blade head ?

Sean

[questerng]

Hi guys,

I'm really interested in this twinn-rex Tandem rotor heli..

I've got no experience in this at all.. is it difficult to build..

I only have a bit of experience in the single rotor heli.. i use to fly a trex 450.. now flying a Trex 600E..

thanks in advance..

[v22chap]

bond 007
Joe is working on some 3 bladed heads soon ...be patient and wait ,,,cause if the heads are anything like the bird he just gave us they will be well worth waiting for :)

[Gra55h0pper]

Hi All,

After having been busy with some other projects the past months, I'm now ready to resume the Twinn-Rexx build with the body assembly! I've received the body from Tech-MP a couple of weeks ago (thanks Joe!) and it looks great! Please see http://www.tech-mp.com for more info.

Here are two "before" pictures showing the body and parts as I received them from Joe. As before, excellent quality. Joe definitely has an eye for detail!

More to come, stay tuned...

H0pper.

[v22chap]

Oh ,, boy here we go ,, want to see how that body fits on and looks in the air ... and darn ,, I have spent to much already this month and will have to wait a few ...even though it is only a few bucks .... got to take care of the bills first .