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Seagull Piper Twin Comanche

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Old 04-29-2012, 06:55 AM
  #26
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Default RE: Seagull Piper Twin Comanche


Quote:
ORIGINAL: c_nut

The rest of my day was spent on the age old dilemma of cowlings....... To cut or not to cut.......
" hot air output must be , @ least, twice the input section " ...

Quote:
I desperately wanted to avoid cutting an opening for the engine head
You could solder the glow heating wire on the connection pin of the glow plug ... I already did it ...

Quote:
This introduces yet another set of wires. There will now be 9 plugs to connect on each wing!!!!!!
You could try the Multiplex " green " plugs ( 6 contacts ) or DB9 or even DB 15 informatics plugs ... often used aboard big scale gliders and good behaviour against vibes ...

Alain
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Old 04-29-2012, 02:35 PM
  #27
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Default RE: Seagull Piper Twin Comanche


Quote:
ORIGINAL: Acetronics

" hot air output must be , @ least, twice the input section " ...
Definitely agreed and familiar with the recommendation. Will open up the underside vent if necessary :-)


Quote:
You could solder the glow heating wire on the connection pin of the glow plug ... I already did it ...
Hmmmm, glow plug replacement would be a task but that doesn't happen often theses days....... I like the idea

Quote:
You could try the Multiplex " green " plugs ( 6 contacts ) or DB9 or even DB 15 informatics plugs ... often used aboard big scale gliders and good behaviour against vibes ...
Well those 9 plugs just became 10 plugs (I forgot about the retracts) I've heard good things about the multiplex plugs, I tried a multi-pin connector on my 96" Cessna but removed it after I noticed it not connecting sometimes. the general consensus was that I needed gold plated pins if I wanted a good connection ?????

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Old 04-30-2012, 12:14 AM
  #28
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Default RE: Seagull Piper Twin Comanche


Quote:
ORIGINAL: c_nut


Well those 9 plugs just became 10 plugs (I forgot about the retracts) I've heard good things about the multiplex plugs, I tried a multi-pin connector on my 96'' Cessna but removed it after I noticed it not connecting sometimes. the general consensus was that I needed gold plated pins if I wanted a good connection ?????

Your Thoughts
Craig
Hi, Craig

Good quality connectors are generally gold plated - just a "flash", do not dream - ... ( try to avoid chinese junk [&o] for these ... ) I think Mouser , Farnell or DigiKey could provide good ones. you also could dismantle ( good quality ! ) informatics cables.

If your connectors "sleep " in a cool and dry place, there shouldn't happen any problem ... even if not gold plated. My old 30+ Years Graupner C505 servos and C16 Receivers have NOT goldened plugs and I never saw any problem with them ...

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Old 04-30-2012, 05:33 AM
  #29
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Default RE: Seagull Piper Twin Comanche

Today's trip to the electronics shop (Jaycar) turned into one of those half day outings, I also managed to squeeze in a quick visit to my local hobby shop too

I ordered a couple of Aluminium Ultimate spinners (the ultimate is a sharper pointy spinner, closer to the shape of the ones on the real aircraft) and I picked up a length of 0.5mm piano wire.

From the electronics shop, I collected the following;

2 x Sub C 3300mAh NiMH batteries (for the onboard glows)
2 x 3.5mm switching phono sockets (for the charging the batteries onboard)
2 x 3.5mm phone plugs, 4 x 4mm banana plugs and some wire (to make up a couple of charging leads)

It took me the rest of the day to complete the cowl mounting and onboard glow on just the port wing

I had thought a lot about Alain's suggestion of soldering the glow wire to the plug and the thought of not having to open up the cowl for the plug boot was becoming all consuming as I looked for possible solutions. I remember (about 30 years ago) that there was a glow plug clip that clipped into the grooves on the glow tip a bit like a bonnet clip, but I was unable to find anything like it......... that's why I bought the 0.5mm piano wire.

First photo shows the clip I managed to form using a small pair of long nose pliers, second photo shows my home made glow clip all soldered into the glow driver wire and attached to the plug. A nice low profile finish and its easily removed if I need to change a plug.

Third photo is the 3300mAh Sub C mounted to the back of the nacelle and the Fourth photo shows the extra spacers I added to the mounting block and the charging socket for the battery. The important thing here is to use a switching socket so that when you insert the charging plug (just a 3.5mm phono plug) it disconnects the circuit to the glow driver and only directs charge current to the battery. That way you know your glow driver is isolated during charging.

I thought about mounting the charging socket through the fibreglass. It would have been easier and a lot less stressful but the extra effort was worth it since the cowling can be removed without disturbing any of the connections.

The final few photos show the overall layout, the extra spacer on the outbord mounting block and a closeup of that charging socket with the cowl on. Plus the nice little rivet style wood screw (hex key drive) that i used instead of those ugly big ones that come in the kit.

Tomorrows Job.......... do the same to the starboard wing and then I can look at the fuel tanks and cutting out for the needle valve and muffler.


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Old 04-30-2012, 06:11 AM
  #30
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Default RE: Seagull Piper Twin Comanche

Nice job, Craig ...

where do you find the "ultimate" spinners ???

I remember having seen some only from Tru-Turn ( ouch 120 US$ for a 2" pair ... big hole in the bank account [&o] )

Alain
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Old 04-30-2012, 03:28 PM
  #31
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Default RE: Seagull Piper Twin Comanche


Quote:
ORIGINAL: Acetronics

where do you find the "ultimate" spinners ???
"Ultimate" refers to the spinner shape, and yes, the Tru-Turn ones tend to be a bit expensive, but they are a good spinner

My local hobby shop stocks the "Phoenix Model" brand. They are not a high gloss polished finnish but more of a brushed finnish and a lot cheaper than the Tru-Turn. I will post a photo of the box and spinner when they arrive (the 49mm size was not in stock yesterday)

Or you could try a search for Phoenix Model SUL01

The Manufacturers websiteappears to be limited access but you can see a picture of the SUL01 spinner there

Craig

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Old 05-01-2012, 03:54 AM
  #32
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Default RE: Seagull Piper Twin Comanche

Hi, Craig

Thanks for the tip ...

Found it AVAILABLE ( ) here : http://www.stevewebb.co.uk/index.php...UL01&area=ACCS

Alain

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Old 05-02-2012, 01:48 AM
  #33
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Completed the nacelle and cowling fit-out today except for the throttle linkages.

I want to use either a clevis or ball link on the carburettor throttle arm rather than the Z Bend as suggested in the kit. I used the Z Band arrangement on my Dual Ace and felt that there was a little too much free play. Obviously with the twinsync, it will be beneficial to minimise any play on the throttles. I also noticed that the hole in the firewall for the throttle pushrod would be better in a different position, so I'll come back to throttle linkages later.

Cutting cowlings has always been a long job for me. I'm tend to take out a little less than I think, then refit the cowling, check, remove, dremel, refit etc etc etc. Perhaps I'm too fussy but I think the effort is worth it even if it did take all day to cut the two

Generally, I cut my cowls to allow removal without having to remove the muffler, but in this case, I felt it better to keep the structural integrity of the cowl and the finnish is much better this way for this aircraft.

You will notice that the hole cut for the needle valve is a little oversize, this is to allow access to the front muffler bolt and also to make it easier to remove the cowl without removing the whole needle valve assembly from the carburettor (I do need to remove the needle itself, but can live with that.) The small hole behind the needle valve allows access to the rear muffler bolt, and the hole underneath the carburettor is for adjusting the idle mixture.

I also fitted the nose cone using Three (one each side in the top stripe and one underneath) of those nice rivet head wood screws that I used on the nacelle cowlings.

I really couldn't come to terms with that moulded in "red light" in the nose cone........ I was going to paint it out with white, but I had a spare white LED and decided to put it in there instead. (not strictly scale, but it looks cool )

I've included some photos of the lights on in full daylight, the photos probably show them a bit dimmer than they appear in real life but I expect that they will be quite visible in flight even in daylight.

Not photographed, but I fitted the fuel tanks as well. First job was to throw away the nylon tubes supplied with the tanks and bend my own from brass tube. Over the years, I have tried all sorts of fuelling systems, quick valves, etc. Eventually, these fancy systems all seem to fail, so I now fit all my planes with a three tube tank. The pressure/overflow tube bends up to the top of the tank and connects directly to the muffler pressure nipple. A single clunk is used on the pickup pipe which is then connected directly to the carburettor and the third pipe is bent down to the bottom/front of the tank and is connected to a standard 1/4 turn fuel dot. This way I can fill without removing any hoses, just observe overflow from the muffler when full and to drain the tanks at the end of the day, simply angle the plane nose down and drain through the fuel dot pipe. (pictures are a bit difficult but let me know if you want a diagram).

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Old 05-05-2012, 02:10 AM
  #34
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Default RE: Seagull Piper Twin Comanche

Throttle linkages done, fuel dots installed and the spinners arrived

So I decided not to use the supplied pushrods for the throttles and instead went with a more rigid arrangement made up of a standard pushrod with a threaded coupler soldered to the cut end and ball links on both ends. This has given me a nice positive throttle link with zero free play. The angle at the servo end provides fuel tank clearance at full throttle.

Photo 3 shows those new spinners - one word.......... awesome There was no need to modify the blade cutouts on the spinners, my APC 11x6 props fit perfectly with a nice amount of clearance.

I drilled my fuel dots in on the underside of the cowl, they will be easy enough to get to, there is plenty of room in the cowl to allow about 100mm of excess tube to make life easy and they wont be visible to the general observer (unless they are on their hands and knees)

I took today of building to enjoy a great day of flying and I'm taking tomorrow of the build to spend with my daughter but the retracts have arrived so that ill be the next task. There has been a fair bit of discussion on other threads and a few different approaches to the retract solution. Some pretty and some pretty ugly. I'm still keen to adapt the original oleo struts to the retract units so stay tuned for the outcome.

Feel free to comment, I'm open to all suggestions, the more ideas the better.

Craig
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Old 05-05-2012, 04:00 AM
  #35
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Default RE: Seagull Piper Twin Comanche

Hi, Cnut

Nice spinners !!!

Halas, by here, they are out of stock " for a while " [:-] I finally turned to a couple of Tru-turn ... relatively affordable , found on Ebay ...

For the retract problem ...

1) front gear
- a 105 ° action ( http://www.advantagehobby.com/124072...11105/?cat=691 ) is a simple solution, with limited eventual sanding of the mounting blocks ...

one must check everything closer as genuine wheels are clearly oversized ... [:-]

2) main gear
- placing some carbon fiber to strengthen the existing ribs before sanding them looks quite easy and strong enough ...

Alain
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Old 05-05-2012, 04:16 AM
  #36
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Default RE: Seagull Piper Twin Comanche


Quote:
ORIGINAL: Acetronics

1) front gear
- a 105 ° action ( http://www.advantagehobby.com/124072...11105/?cat=691 ) is a simple solution, with limited eventual sanding of the mounting blocks ...

2) main gear
- placing some carbon fiber to strengthen the existing ribs before sanding them looks quite easy and strong enough ...
good idea on the nose gear, I already have the tricycle set which s a 90 degree, maybe I can exchange it otherwise I will have to go with the sanding option.

I don't have too many concerns about the strengthening for the mains, what I'm trying to decide is what to do about the length difference between the mounting point and the wheel well cut out........ are you going to move the mounting point out toward the wingtip or are you going to recut the wheel well closer to the fuselage ??????

Craig

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Old 05-05-2012, 04:23 AM
  #37
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Default RE: Seagull Piper Twin Comanche

Quote:
ORIGINAL: c_nut


what I'm trying to decide is what to do about the length difference between the mounting point and the wheel well cut out........ are you going to move the mounting point out toward the wingtip or are you going to recut the wheel well closer to the fuselage ??????

Craig
much easier to modify a bit the wheel well !!! ( the awful plastic bit will be replaced by "classic" balsa fairing ... )

Alain
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Old 05-05-2012, 04:32 AM
  #38
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Default RE: Seagull Piper Twin Comanche


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ORIGINAL: Acetronics

much easier to modify a bit the wheel well !!! ( the awful plastic bit will be replaced by "classic" balsa fairing ... )
That's what I was thinking too, my thought was to cut the covering along the centre line of the retract and then at 90 degrees to that at both ends (probably along a rib line) then fold back the covering to reveal the area to be worked on.

Once the mods have been done and boxed in with thin balsa sheeting, I could then fold back the covering, iron it back into place and only require a little pin stripe finishing over the cut lines.

Your thoughts?

Craig

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Old 05-05-2012, 04:53 AM
  #39
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Default RE: Seagull Piper Twin Comanche

I do agree ... probably the simplest method that won't induce any weakness ...
the cleanest too !!!

Alain
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Old 05-07-2012, 03:05 AM
  #40
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Default RE: Seagull Piper Twin Comanche

First job this morning was to adapt the fixed oleo struts from the kit to the E-Flite 60-120 retracts. I have only done the main gear today but should be able to show you the nose gear tomorrow.

Simply remove the 3 grub screws from the top end of the strut and remove the aluminium plug with the fixed gear wire, the fixed gear wire was a fairly tight fit and had to be punched out then refit the plug back onto the strut.

Cut a 40mm length of wire from the legs that came with the retracts and a 25mm length of 7/32 tube.

Tap the wire into the tube, drill the aluminium plug in the strut to suit the sleeved wire and assemble.

Easy enough(the nose gear will be more of a challenge as I may need to cut a circlip groove)


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Old 05-07-2012, 03:42 AM
  #41
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Default RE: Seagull Piper Twin Comanche

Next came the wing modifications.

I started by cutting the covering 45 degrees in from the outside corners of the retract mount back to the centre line of the leg cavity. Then I extended the centre line all the way to the inboard end of the wing and cut the covering along that line. Now I could gently peel back the covering to reveal the work area. (photo 1)

There has been a bit of debate about the wing rib that stops the retract unit from sitting right down in the wing. I had a good look at this and the surrounding structure. Given that this area is sheeted and double sheeted and that the retract unit itself also acts as a structural "bridge", I believe there is no real concern with removing the section. (photo 2)

A home made circle cutter makes easy work of recutting the wheel well's (I just slot a piece of hardwood and CA a blade in place then use a picture hook nail for the centre pin) The centre point for the new cutout was marked at 72mm from the inboard end of the wing and the diameter was identical to the existing cutout. Once the cut has been made, spin the off cut around and it can be used to sheet the old cutout (photo's 3,4,5,6)

I then used the plastic wheel well but I slid it inside and glued (CA) it to the underside of the wing sheeting (this will give me a nicer finish than sticking it on the outside) Add some light sheeting to box in the rest of the cavity and you have a pretty quick and easy wheel well that will accommodate the supplied gear door and even have it sitting flush once I shorten it and figure out how to mount it to the strut. (photo's 7,8,9)

Sealed it all with dope, ironed the covering back in place and added a small strip of covering over the cut line (between the well and the end of the wing) then some white paint and as soon as that dries, The retracts can be screwed in place.(photo's 10,11,12)

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Old 05-07-2012, 09:11 AM
  #42
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Default RE: Seagull Piper Twin Comanche

Nice work Craig. I like what you did with the main wheel wells. Those "Ultimate" spinners are very nice too. Hoping I can grab some in the States

Subscribed. Thanks for the mention in the first post to my Comanche Electric Thread.

It should be interesting for both versions of our builds, what the total air-up weight will be. Glad we have both versions "covered".

Nick
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Old 05-09-2012, 07:53 AM
  #43
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Default RE: Seagull Piper Twin Comanche


Quote:
ORIGINAL: nioa

Nice work Craig. I like what you did with the main wheel wells. Those "Ultimate" spinners are very nice too. Hoping I can grab some in the States

Subscribed. Thanks for the mention in the first post to my Comanche Electric Thread.

It should be interesting for both versions of our builds, what the total air-up weight will be. Glad we have both versions "covered".

Nick
Hey Nick,

thanks for dropping in, I'm pretty happy with the way the mains turned out and I didn't have to do as much chopping on the nose gear as I thought.

It's a bit late to do an update but I will try to get my nose gear mods posted tomorrow.

If you cant find the phoenix ultimate spinners, tru-turn do an ultimate as well which can be ordered direct from Tru-Turnfor $31.95. They provide a choice of slot sizes or you can tell them what prop you are going to run and they will custom slot to match.

I should be able to get an accurate flight weight for you tomorrow.

Craig

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Old 05-10-2012, 05:56 AM
  #44
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Default RE: Seagull Piper Twin Comanche

Ok, well the nose gear went in without too many problems, there have been a number of solutions presented on other forums and builds, mine is by no means the only option but I am happy with the way it worked out and it didn't require any hacking of the airframe.

Modification of the retract was similar to the mains except this time the tube required is 3/16th. I cut the retract wire at the point where it started to curve into the spring and that left me with sufficient straight wire to mount the strut. (photos 1,2,3)

I mounted a separate servo for the steering which will just be "y" leaded to the rudder channel (photo 4)

I then mounted the retract into the unmodified mounting point but changed the mounting angle by putting two washers under each of the front mounting screws. This changes the angle to retract further into the fuselage. Then, after reading that one of the tricks to overcome "landing challenges" with the real aircraft, was to change to a smaller nose wheel, I thought I would do the same to mine. with the wheel mounted in the strut, you can present it to a disk sander at an angle that causes the wheel to turn while it is being gently sanded back to about 2 1/4" diameter. the result is a nose gear that now successfully retracts far enough into the fuselage for the gear doors to close (photo 5)
A broken muffler extension provided the perfect piece of aluminium to craft a pushrod guide for my steering linkage (photo 6)
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Old 05-10-2012, 06:12 AM
  #45
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Default RE: Seagull Piper Twin Comanche

After sorting out the nose gear, I went back to finalise the doors for the mains, I little bit of fiddling here but it was all worth it in the long run (photos 1,2)

I really liked Nick's idea
(over on the electric build)of using servo's and a sequencer to open and close the gear doors, I am not overly happy with the supplied mechanism, it works, but the springs end up fighting the doors and so they close at the front but end up bulging open at the back. I will be using Nicks idea to modify my gear doors as soon as my gear door sequencer arrives.

Anyway,......... for now, Gear down.......... Gear up........ (photo 3,4)

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Old 05-10-2012, 06:33 AM
  #46
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Default RE: Seagull Piper Twin Comanche

Finally, I can move onto the tail section and get some radio gear in the fuselage.

Just when I thought I'd finished all the challenging parts, I remembered I had two more lights to put in the tail section. The rotating beacon and the rest facing white nav light in the rudder.

What I needed was a very long 5mm drill........... to my surprise, I could actually get one, but the price was prohibitive for a drill I may never need again. Solution............. well, I still had a good length of bass tube that I used for the sleeve on the nose gear. Why not get inventive with the Dremel and turn the tube into a hole saw

I've decided to use a 2500mAh LiFe battery for the flight pack, it's a bit long for the battery compartment but it fits easily through the hole in the front of the compartment. So some foam padding and some velcro to stop i sliding forward is all that I needed. The great thing was that with the battery mounted here and the rest of the radio installation contained behind the wing tube, centre of gravity is right on the recommended 110mm without any additional weight.
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Old 05-10-2012, 06:51 AM
  #47
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Default RE: Seagull Piper Twin Comanche

Well it's late, but she's finished

too late to lake photos and I still have a couple of mods that I want to make. I'm waiting for a nice lens for the rotation beacon LED but it hasn't arrived yet so I have fitted the led temporarily until the part arrives. The other mod I want to make is to convert the gear doors to servo and sequencer operation but again, waiting for parts to arrive.

So tomorrow I will take some photos and then I'll run up the engines, tune up, set throttle linkages and finish setting up the twinsync programming.

Saturday is maiden day, forecast is fine with 10-15Km winds so I'll be heading to the club to see how she fly's

Finished weight (dry - no fuel) is 5.92Kg. Certainly on the heavy side, but I expected that with all the extras and I don't really expect it to be a problem.

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Old 05-10-2012, 07:31 AM
  #48
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Default RE: Seagull Piper Twin Comanche

Quote:
ORIGINAL: c_nut

I am not overly happy with the supplied mechanism, it works, but the springs end up fighting the doors and so they close at the front but end up bulging open at the back. I will be using Nicks idea to modify my gear doors as soon as my gear door sequencer arrives.
Hi, Craig
looking at the different pics available on the web ... the main gear shows two versions:

1) double fork holding the two sides of the wheels axles
2) " mustang style " with the wheel facing outside ( facing wing tips when out )

for the " mustang style " ... no need to have modified the gear doors ...

yes, you're right ... I'm somewhat late ... [:-]

Alain

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Old 05-10-2012, 04:46 PM
  #49
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Default RE: Seagull Piper Twin Comanche


Quote:
ORIGINAL: Acetronics

the main gear shows two versions:

1) double fork holding the two sides of the wheels axles
2) " mustang style " with the wheel facing outside ( facing wing tips when out )

for the " mustang style " ... no need to have modified the gear doors ...
Yes, I found the same thing when I went looking for photos of the undercarriage. There were a few challenges to overcome which lead to my "fork out" decision.

My goals were;
Avoid packing main gear outside wing surface
Flush mount gears doors
Use supplied Oleo's

Problems faced with fork's inside;
Not enough room to fully retract inside wing (could have ben overcome by packing the retract unit as suggested in manual)
Would have required a cutout in the side of the wheel well for the fork (not a huge issue but not as nice cosmetically)

Problems faced with forks outside;
Not strictly scale (but neither is the rest of the model)
Required a cutout in the gear door to fit around the fork.

Problems faced with both options;
The diameter of the oleo means that it comes right up against the motor assembly when fully retracted (in fact I had to modify the retract unit to stop it from binding - see photo) this also means that there is no room for the gear door mounts to wrap right around the strut so you will have to get creative with gear door mounting either way. Also, the axel in the fork is not at 90 degrees to the strut - not really a problem, I just slipped a piece of tube over the axel and bent it to an appropriate position once everything was installed and I could line it up visually.

So my decision process went something like this;
Fork out was less work
Fork out would give me a way to epoxy the gear door to the fork (because of the cutout) and then use a partial sliding guide further up for support without binding on the retract)
Fork out would "look" like the dual fork version with the gear up (with the gear down and on the grass, I don't think anyone will see them anyway)
Fork out allowed me to meet all my goals.

So there you have it, sorry for the long explanation but perhaps it helps someone else with their decisions.

There is certainly more than one way to do it

Craig

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Old 05-11-2012, 02:23 AM
  #50
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Default RE: Seagull Piper Twin Comanche

sorry guys..........

I got distracted by a few things today. I did manage to get the engines tuned and throttle linkages adjusted so everything is as close to synced as possible without the twinsync connected. Than connected the twinsync and finalised the programming - Ahhhhhhh the beautiful sound of synchronised engines plus the security of throttle cut in the event of a one engine out.

Batteries all charged, fresh fuel mixed, car packed (along with 3 other planes) so I'm ready to go in the morning.

What I did run out of time for was the photos......... So for that I apologise, BUT I will get lots tomorrow at the field and hopefully some video too.

Craig

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