samparfitt

My Feedback: (43)

First picture:
It's nice to have a dremel extension to drill holes close to an object,
such as the mount hole close to the one former.


Second picture:
Speaking previously of possible hinges not being glued,
here's a mount in the nose that was only dry fitted.
A little epoxy fixed that up.


Third picture:
All retracts screwed in.
Presently, only put two screws in for now.
Later, when I get the struts on and check for alignment,
I'll then drill the other two screw holes.
(if I did this in the right order, I wouldn't have to do this!).
(my 'radical side' doing what moves me at the time instead of the proper order).


Tomorrow, my low profile servos may come in and I can finish up the spoiler/aileron section.

Fourth picture:
Nothing to do with P-61's but I'm almost done with those six book cases.
This one is walnut.

samparfitt

My Feedback: (43)

thought I'd give ya' another picture of the steerable linkage with all the parts separated for more clarity.

'Down the road' yet for this but I found the distance from the firewall to the front of the cowl to be 4".
Not a whole lot of room: you guys considered gas may have quite a bit of engine sticking out.
With my OS FX .91's, the engine will be all the way back on the engine mount.

samparfitt

My Feedback: (43)

Not a whole bunch tonight (like twinman says, gotta' work so I can have this hobby).

First picture:
I put a medium Robart air tank in.
The hole in the former is an exact fit for the tank but there's not enough room to slide it in.
I used my razor saw to cut a piece out to slide it in and I can glue the cut piece back in later.

Second picture:
The tank on the right came with the Spring Air's 400 set.
As you can see, the volume difference is significant, and important when moving retracts this size!

Build-n-flyer-RCU

My Feedback: (4)

Wow, you are right. There is only 4", maybe just a tad more, from the firewall to the front of the cowl. A Saito 120/150 would stick out an inch. Even a Saito 100 would have to be pushed all the way back.

Other than Saito 100 and OS 91, what other reliable strong engines will fit properly? A good question for you fellas that are experienced with a variety of different engines..

I'm heading to Dayton in the morning. Gonna take "just a few" pics of the P-61 at the Air Force museum while I am there.

samparfitt

My Feedback: (43)

Wright Pat: about 40 miles from my house: twinman may have the weather but we've got one of the best air museums in the world
in our backyard.

Mounting engines:

First picture:
I've learned in wood working, never measure when the you can transfer measurements directly.
Trying to measure say 13/32" (hmmm, just a hair over that)....forget it!
In this case, I use these.

Second picture:
Can't get any more accurate than that! (which is important for mounting engines).
Again, I center punch it to initially guide the bit.

Third picture:
While it's not necessary, it makes accuracy much easier by using a mini-drill press.
As with the gear mounts, I drill a pilot hole first.

Fourth picture:
Then over to the regular drill press (also not necessary but easier) to drill the final hole.

samparfitt

My Feedback: (43)

First picture:
Some may find this a little anal but I tap and use a locking nut (plastic insert) to hold
the engine to the mount.
The tap will have the bolt, thread and bit size on its shaft ( in this case: 8-32, #29).
There's a lot of vibration up there on the business end and it's no fun having it come loose: not to mention safety (but I will!).

samparfitt

My Feedback: (43)

Engine installation.

First picture:
Front view.
Temporary mounting of engine to the firewall.
The firewall has 'centering' lines on it.
The engine shaft should align on the center of their intersection.
The top mount corner had to be trimmed so it wouldn't interfere with the fuel adjusting screw.
Part of the opposite mount will have to be trimmed for the muffler.
The muffler will have to also be ground down on the corners near the mount in addition to
the area close to the throttle so the connecting rod can move freely.
I will also have to drill/tap a screw with a hole drilled through the screw for pressure to the tank.
This J-tec muffler does not come with this (not sure why!).

Second picture:
Side view.

Third picture:
Top view.

Fourth picture:
with cowl on.
The engine cylinder head just clears the inside of the cowl.
I will probably have to cut a hole for the glow plug.
Later, I will install a remote set of wires a foot back (or so) to route 1.5 volts to the glow plug.

twinman

My Feedback: (2)

Sir,
I admit that I am ( As is most of America) trailing you on this building process.
If you do not have a hole for the cylinder head, is there enough clearance for air flow around the engine and out the edges of the cowls? What I mean is cooling air flow?
Twinman

samparfitt

My Feedback: (43)

Yo Twinman,
'SIR': must be talking to my dad!
Good point: This morning, I checked the back of the cowl: There's a 1/4" at the bottom and none at the top
between the cowl and boom.
That hole in the bottom of the firewall would be cool for routing air,
but it looks like the structural integrity would be lost if an additional hole would be put in the bottom of the booms.
With the radial cowl, there'll be plenty of air going in, just no place for it to go out.
Options look like cutting between the back of the cowl vents and opening those up more or cutting a hole in the
bottom of the cowl.
I'll need one any way for the muffler so I could just make it larger:
cross that bridge later when I permanently mount the engine.

TLH101

My Feedback: (90)

You will need to close off most of the cowl front opening, or open a lot at the rear. You should have at least twice as much exit as entry, to allow for expansion from heat. If you were to put a dummy radial with 1 or 2 cylinders removed from in front of the engine cylinder, and then open up the cowl the size of the cylinderhead around the glow plug, you should good cooling without sacraficing good looks. The quickest way to kill one engine , (or 2) inflight is to overheat them.
Good build thread btw. How yours turns out will influence my decision on this one. I love the P-61.

samparfitt

My Feedback: (43)

Anybody know who makes a dummy radial for this size plane?

TLH101

My Feedback: (90)

I got some for my B-24 from these guys: http://www.darehobby.com/accessories-scaleradial.htm
They are just molded ABS, and don't have a ton of detail, but can be made to look pretty good. And the price is right when you just need the face and not the whole engine.

samparfitt

My Feedback: (43)

Terry,
Thanks for the info.

Not much done tonight.
spent most of it moving a book case to my son's place.

Did get some goodies in though.

First picture:
My APC 4-blade 13.8 X 10's came in.
Center is the OS FX .91 and to the left is the MAS 3-blade 14X7 props that work well with this engine.
From visual comparisons, I think the OS .91's will handle the APC 4-blades.

Second picture:
The low profile servos for the spoiler/ailerons also came in.
The left one is the low profile (Hitec HS-77BB) compared to a 'standard' servo.

Third picture:
Last are the wheels.
I moved up a 1/4" in size to get treaded mains.
These are Robart's 3 3/4" treaded (UX375 #136 on label).
The nose is a 3" Robart treaded (UX300 #133).
They appear to be about proportional to the pictures of the P-61.

Fourth picture:
No words needed!

Tomorrow, I plan on ordering some unibrakes from Spring Air.
I believe part number 35754 should do it.
(can't beat seeing a plane at the end of the runway at full throttle and the brakes on!)

twinman

My Feedback: (2)

If it helps, I wrote a piece on installation of the brakes you are talking about at http://www.rcuniverse.com/forum/m_13...tm.htm#1348349.
Have a good one.
Twinman

twinman

My Feedback: (2)

Build-n-flyer-RCU
Commented about clearance in the cowls for gas. I occured to me VQ is in the process of converting on to Gas for an experiment.
Here are the pictures.
Twinman
PS Don't even ask about details on these engines. Go to VQ, it is something that they are working on. Hope they remember to share when they get it running...Wait....last time an engine quit.......Wait....no problem...is in production, not protype. NOT MY PLANE!!

samparfitt

My Feedback: (43)

Called Spring Air and they are out of the unibrake.
Talked to Dean (who makes unibrake) at www.compactunibrake.com and he's in the middle of selling his company but said Donshobbyshop.com (800-972-6273) should have the universal brake set phase III that is best for the P-61.
I called Don and got that set plus the ultra precision brake valve.
($80 + $59 + $7 shipping).
If you want these, you might want to get them now since it appears that
there's going to be a 'dry spell' while the company is sold.
I checked out Robart's and all I could find was brakes for very large wheels.

Hope to get started on the spoiler/ailerons for tomorrow.

Build-n-flyer-RCU

My Feedback: (4)

I'm still on an engine search. YS-110's would fit quite nicely and have the power to spin 3-blade or 4-blade props with authority, but I've never owned one. How reliable are these, especially inverted? Oh, well, no real rush...

My parts and pieces are starting to arrive and I should be able to get working on my plane in earnest this weekend.

Here are a few pics from my visit to Dayton. Low 30's and pouring rain. Close to a great air museum or not, I'm glad I live in the South!

Walt

kram

My Feedback: (7)

Samparfitt/Twinman:

I'm still cipherin' about powerplants.

If there's only 4" from firewall to spinner, how did VQ fit that gas engine in those pictures?

According to my calculations, a G-26 would stick out 1-1/2" too far, even a Saito 100 half an inch too long.

I'll look up the owner's manual on a 170 radial and see if that would work.

Thanks,

mt

twinman

My Feedback: (2)

Well one I found is at Brison http://www.brisonaircraft.com/2.4_small.htm the 2.4 gas. Spec's show at 5", but not sure where that is measured. RCShowcase has small gas engines at http://www.rcshowcase.com/, but are rear carb. Not sure how difficult to handle that. Go to that site and look at the 1.8 ( No, I am not endorsing that size) with the front induction is the RCS brand. 5.75" long.
I am sure there are others. Ok, so these are a bit pricey....you did not say anything about cost!!!
Twinman
Kram says "I'll look up the owner's manual on a 170 radial and see if that would work. ".....now William Robison is going to get excited. Be careful....he might drool on the idea too much. Bad mental image!!!

William Robison

My Feedback: (3)

Mark:

The Saito FA-72 and FA-82 are just about 4" from the prop drive to the back of the carb. Should mount with no problem. The FA-80, 91 and 100 are roughly 4 1/2" so they should work too, since you need the prop drive a little forward of the cowl ring anyway.

Go to the "Big Block" and it's a different world. The FA-120 is almost 6" from the prop drive to the back of the carb.

Bill.

Alvin

My Feedback: (6)

I did some measurements and found if you cheat the cowl forward about 1/4 inch you can get a First Place Engines 1.3's on it. I hate cleaning up glow fuel slime! Weight wise they are about 6 oz heavier than a big 4 stroke. Mine are due in next week. I will be using Robart retracts on it due to a more scale forward rake on the nose wheel strut. They are due in 2 weeks BUT with Robarts reputation I'm not holding my breath...[:'(]

AL.

twinman

My Feedback: (2)

William,
Why did I KNOW that the sound of a radial would make your ears purk up!!!!!!
Now, who else would almost instantly have that kind of information!!!!!
Tee Hee,
Twinman

William Robison

My Feedback: (3)

Twinman:

Being a Saito nut here's a few I have sitting and waiting. Since I have them it's easy to pick one up with a ruler in my other hand.

The pair of FA-72s is going in the Duellist 2/40 under construction, the FA-80 isn't committed, if I get another then the Super Duellist. The FA-120 is going in my Cessna Bobcat along with the one I'll remove from my Ultra Stick, and the FA-150S is going on the Ultra Stick.

Now I have to find another FA-80.

Bill.

kram

My Feedback: (7)

William/TwinMan, et al:

Thanks for the input.

I don't think .80 FS's will fly this plane well, and as you pointed out, the 1.00's & 1.20's are longer.

I'm not sure a 170 radial was anymore than a figment of my imagination....can't find it under O.S. or Saito. The O.S. 160 twin would seem to be a nice (but pricey) solution, as well as an answer to my obsession with avoiding inverted glow, but the 160 is considerably longer than an .80, and I don't imagine the 13 oz fuel tanks would last long with 160 twins!

Gas engines would sip fuel compared to glow, and work well inverted, but I worry some about vibration on an ARF airframe.

Maybe I should just K.I.S.S. and follow samparfitt's lead with 91 2-strokes.

I can tell you from experience with my Ziroli-61 that it doesn't look that bad with the props set almost 1-1/2" forward of the cowl to accomodate G-62's with spring starters. And the C.o.G. worked out perfectly that way.

Samparfitt, I'll be anxious to hear where the C.o.G. winds up on yours.


mt

kram

My Feedback: (7)

Alvin:

Any experience with the vibration level of the First Place 1.3 c.i.'s ?

mt