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Another Twin-Air .45 Build Thread?

Old 03-07-2005, 09:35 PM
  #26  
William Robison
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Default RE: Another Twin-Air .45 Build Thread?

Steve:

Just be sure your internal bracing is up to whatever rails you use. In a hard enough landing, if the rails don't split you will have internal structural damage. Split rails aren't fun, but they are more pleasant than replacing spars and ribs.

Bill.
Old 03-07-2005, 09:38 PM
  #27  
SteveTrofemuk
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Default RE: Another Twin-Air .45 Build Thread?

Landing gear is often the weakest point on our aircraft. I usually beef up the gear attachment points pretty well. I will admit this is the first plane I've built that doesn't have the main gear in the fuse. Sounds like the best bet is plywood laminate. While I currently fly from pavement things change. I've been a member of a few clubs and over the years have lost two flying sights to "urban sprawl". I think I'll build it tough and go with ply--just in case. And let's face it, many of my landings look like "carrier landing" attempts.
Old 03-08-2005, 04:26 PM
  #28  
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Default RE: Another Twin-Air .45 Build Thread?

Here are some pictures of the finished landing gear mounts made from existing stock and 1/4" ply. Since I was asked to be detailed in the landng gear area, I thought it appropriate. The gear is held in place one 1/4 ply rails. The ply railes are epoxied to ply ribs and ply reinforcements that came with the kit. Some relief of the ribs and reinforcements was required--but not much.

Do I need to reinforce the gear well or perhaps box it in with balsa? Being my first retract aircraft I'm hunting suggestions.

Also on a side note, I lifted the winig from the building board today and it is quite possibly the straightest wing I have ever made. The building technique is a little odd to me--build on a flat surface from the bottom sheeting up--but it works very well. It's awfully pretty to see wing ribs lined up so nicely. Very good engineering. Tahnks NE Aero...

The last picture is just me tacking things in place and seeing how it's all gona fit together.
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Old 03-08-2005, 04:57 PM
  #29  
William Robison
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Default RE: Another Twin-Air .45 Build Thread?

Steve:

The gear well should be sealed as well as possible, not for strength, just to keep trash out of the wing.

An easy trick for the round part for the wheel is to cut a section from a styrofoam cup.

Bill.
Old 03-09-2005, 12:44 PM
  #30  
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Default RE: Another Twin-Air .45 Build Thread?

Another Twin Air with B&D retracts, good choice. I had several flights with my Twin Air and these retracts, solid units.
Here is a pic of mine, may help some.
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Old 03-09-2005, 12:48 PM
  #31  
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Default RE: Another Twin-Air .45 Build Thread?

Bill brought up a really good point, my front nose given the complexity was hard to seal. I fly off grass and I was forever removing grass etc. Here is a pic of it all done!
Have fun, it's a great build!
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Old 03-09-2005, 01:10 PM
  #32  
SteveTrofemuk
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Default RE: Another Twin-Air .45 Build Thread?

Hughes500E:
Nice pics and a great looking plane. Now I'm starting to wonder if I've mucked up the gear. I noticed your mains aren't as long as mine. Have I goofed? If so I'm gonna have to find a way to live with it what with one wing panel 98% done.

If you have any detailed pics of your nose gear I'd appreciate it. I don't anticipate getting to the fuse this weekend, but I always try to plan ahead.

Again--nice look plane. I really like your color scheme.
Old 03-09-2005, 02:26 PM
  #33  
William Robison
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Default RE: Another Twin-Air .45 Build Thread?

SteveT:

You will notice also SteveH has stolen another of my pet tricks; symmetric engines. Look at his mufflers.

I like your plane, SteveH, don't think i've seen any pictures of it before.

Bill.
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Old 03-09-2005, 05:32 PM
  #34  
Hughes500E
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Default RE: Another Twin-Air .45 Build Thread?

Oh my, Bill I thought I had shared the pics already, with all the help I had and all
Those MVVS's are counter rotating, I love this hobby!
Steve T: given the chance I would swap out my gear struts for longer ones, works well but I think you're going to be better off!
I never took any pictures of the front nose gear accept the one pictured. I'll try and explain what I did:
I made a platform for the front steerable nose gear out of ply. I mounted the gear (with the wheel extended straight up) to the platform. Then, the balsa doublers forward of the thick ply (fire wall) in the nose of the fuse were cut (slotted) to accept the platform and reinforced with triangle stock. Then, I had to slot the thick ply (firewall) to accept the strut once retracted. The steering mech on the B&D works great, has more than enough room to operate etc.
Hope this gives you some ideas!

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Old 03-10-2005, 05:59 AM
  #35  
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Default RE: Another Twin-Air .45 Build Thread?

Hughes500E:
How did you get an engine that rotates the opposite direction? Is that something all engine manufacturers do but don't advertise? Also, do you have to use a "pusher" prop on the opposite rotating engine? Just wondering. I like the idea--I imagine it has the affect of cancelling torque effects. You must have really smooth takeoff runs and turns. [8D]

On another note, I was finishing up the wing on mine last night by boxing in the gear well and a thought occurred to me.

--that doesn't quite convey the meaing. let me rephrase....

A thought slapped me in the face like a cold dead herring.

--Nope--let me try again...

A thought hit me like a Mack truck doing well over 100 miles an hour on a a foggy night with a bucket load of cold dead herrings epoxied to its grill. (yeah--that's about right) Where am I gonna stick the throttle servo? I must be getting old I usually plan for these things. The original plans have the servo mounted upside down at an angle right were my gear piston is. Well--it can't go there. I'll have to find another spot. Looks like I can mount the servo right side up between the main spar and the gear piston but the linkage will be a little different then what was originally drawn. How did you mount yours?
Old 03-10-2005, 09:40 AM
  #36  
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Default RE: Another Twin-Air .45 Build Thread?

SteveT:

Addressing the counter rotating engines. I don't know, but I suspect MVVS will supply the cranks for reverse rotation. OS has supplied them in the past, I don't know about current availability.

I have two reverse cranks for the K&B 4011 engines, I only had to wait a year and a half for RJL to make them. They may have a supply on hand at the moment, Randy seems to make a production run when he gets enough orders.

Reverse rotation engines are not the problem, propellor selection is where you have trouble.

Master Airscrew has some "Pusher" props, as does APC. Zinger has the largest selection, including two, three, and four bladed props.

If you want to use counter rotating engines the first step is to be sure you can get the props you need. Get the equivalent normal rotation prop and test it on the engine you plan to use, then if OK you can spend the extra money for the reverse prop. I say this, if you can get the size you want from MAS or APC they aren't too expensive, and the Zinger composites are fairly cheap too. But if your prop size is one of the "Special" Zingers, you can drop $30 for each one. Expensive to pick the wrong size.

I have been the CR route, it's a lot of trouble. If you have to do it the advantages are there, but I really don't think they are as great as the disadvantages.

A slight exception in in the larger planes using three or four bladed props. Zingers larger multi bladed props cost close to the price of the reversed equivalents, CR just adds around $8 to the price on a three blade for example, and the "Wow" factor of CR makes it worth while.

Yes, CR does make a difference, it eliminates having a "Critical" engine for single engined flight, but in most cases I don't think it's worth the bother.

Your decision.

Bill.
Old 03-10-2005, 10:20 AM
  #37  
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Default RE: Another Twin-Air .45 Build Thread?

The cool factor makes it worthwhile [8D] but, you're right, little more trouble.
I managed to use two APC props, 1 normal 11x7 and one pusher (mounted backwards), both engines were within 50RPM and running sweet. MVVS makes reverse rotating cranks.

I used two micro servos for my throttles Hitec 81's , right side up behind the tanks with flexible cables. Little tight you're right but, there's room
Old 03-10-2005, 11:32 AM
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Default RE: Another Twin-Air .45 Build Thread?

I understand the reversed crankshaft rotation; but where did you find the reversed manifold?

I assume the engine was made that way?
Old 03-10-2005, 12:40 PM
  #39  
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Default RE: Another Twin-Air .45 Build Thread?

SteveC:

If you are talking about the picture I posted of the K&B engines, the mufflers shown are no longer available, sadly. They could be mounted any way, and the exhaust stacks could be rotated up to 180 degrees, no set position. Picture attached of a larger one on a K&B ringed 61.

Most mufflers can be mounted in reverse, some such as the Super Tigre, have the mounting centered on the muffler so it is at the same height when reversed. The stock K&B is slightly off center, reversing it works too. The Fox mufflers with the angled head pipe section would look strange.

The carb can also be mounted in reverse to keep the needles outside, some such as the K&B "Ribbed" carb work equally well rotating in either direction from full to idle. Genuine Perry carbs can be modified to do this also. If your carb wont allow it there is still no problem, just reverse the throttle servo to push to high speed instead of pull, or vice versa. Problem with reversing he mounting of a carb is the fuel inlet nipple. If you can get the hose on without hitting the prop you're fine.

Bill.
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Old 03-10-2005, 09:15 PM
  #40  
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Default RE: Another Twin-Air .45 Build Thread?

One of the nice things about MVVS engines. Before the first start, you can decide on the locatation of the cylinder, either side or reverse exhaust, very nice.
Old 03-11-2005, 05:33 PM
  #41  
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Default RE: Another Twin-Air .45 Build Thread?

Steve,

A couple of ideas come to mind about solving your throttle servo location dilemma.

The first is the old way of doing things: that is, put a servo in the center of the wing and use it to drive a bel-crank to the engine linkage in each nacelle. You keep your engines in sync with mechanical adjustments to the linkages.

The second is to use two micro digital servos (like the JR DS368 or similar) and drive the throttle linkage that way. You'll need a hatch of some sort for maintenance unless you feel comfortable burying a servo, or two, behind balsa :-P

Old 03-11-2005, 05:50 PM
  #42  
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Default RE: Another Twin-Air .45 Build Thread?

Hi John, I was wondering when you were going to chime in!

Instructions on how to install retracts on the TA would be another nice addition to the plans, wouldn't it?
Old 03-11-2005, 06:08 PM
  #43  
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Default RE: Another Twin-Air .45 Build Thread?

Walt,

I've considered adding retracts to the plans, but the problem is that there are so many different types of retracts out there that what I put on the plans would be wrong most of the time.

Old 03-11-2005, 06:25 PM
  #44  
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Default RE: Another Twin-Air .45 Build Thread?

John:

For an inexpensive plane inexpensive retracts would seem to be desired. I have used and recommended the B&D gear set for several years, both Steve H and Steve T (this thread) are using them.

The complete pneumatic set retails for $70-$80, including everything needed to go in the plane.

You might get a set (Tower sells them, among others) and play with them. Bet they will please you.

But for now, you have kits to pack. Get busy!

Haw.

Good to see you on line, John.

Bill.
Old 03-11-2005, 08:05 PM
  #45  
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Default RE: Another Twin-Air .45 Build Thread?

Bill,

Seems like ages since we spoke!

I've taken a look at the B&D retracts. I'll contact them on Monday and get hold of a set. Maybe I can offer some of the kits with retracts included and skip the wire gear to keep the cost increase to a minimum.

I was planing on including retracts in the plans of another twin we're working on, but that's another thread...
Old 03-11-2005, 08:25 PM
  #46  
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Default RE: Another Twin-Air .45 Build Thread?

John:

The B&D set will work on that "Other" twin also, if the blocks are all well hollowed and the build kept light. Helps to stay off grass too.

Maybe B&D would be interested in making slightly stronger sets? Current ones are good to about 12 pounds, wouldn't take much.

Best thing about the B&D is that they are guaranteed forever, against everything but wear. And I've not seen any amount of wear in any of them. Haven't broken any either, but I've had to straighten a gear wire or two.

I've thought about using the titanium struts from MK and others, but can't really see the need. Yes, there's a set screw holding the, they can be replaced.

Pictures are the mechanically operated version.

Bill.
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Old 03-11-2005, 10:20 PM
  #47  
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Default RE: Another Twin-Air .45 Build Thread?

I would and probably will buy another set without thinking about it. My current set holds a charge for more than 24 hours LOL
Very positive lock and quite light.
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Old 03-13-2005, 04:44 AM
  #48  
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Default RE: Another Twin-Air .45 Build Thread?

It would be cool if the kit had an option to ship with retracts. I have decided to get an TwinAir 45 and would love it with retracts.
Im only waiting for them to be in stock again and info about whether NE-Aero ships to Denmark. I have emailed NE-Aero and I hope
for an answer that tells me that they do ship outside the US.

/RCer.
Old 03-13-2005, 05:23 AM
  #49  
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Default RE: Another Twin-Air .45 Build Thread?

All:

John Marien is a victim of his success. The Twin-Air has become so popular that Northeast Aerodynamics is shipping them as quickly as they can make and package them, leaving very little time for anything else.

NE-Aero has hired more help and bought new machinery, we can all hope this will ease the production problems and let John finish both the Zeph-Air biplane (see it on his web site) and his new series of twins,

Shipping into Europe has some extra paper work along with the higher transportation costs, I've done it a few times. Each country has its own regulations concerning import duties also. I've never shipped into Denmark, can't say how that one would be. I'll assume you've already contacted John about it.

Bill.
Old 03-13-2005, 07:23 AM
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Default RE: Another Twin-Air .45 Build Thread?

Success for a good reason I assume . It looks like a great plane. Yes I have contacted them per email and they told me they will look into it.
I have waited about two weeks for more info but with them being so busy I guess I will have to be patient. I thought shipping to any country within
the European Union would be the same. Doesn't UPS, DHL or FedEx have standard customs forms for shipping goods to the EU?

Regards
/RCer

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