Magnum RC

I KNOW I know....I changed the bloody thing once to what it is supposed to be, today I changed it again. Perhaps the save will take...

Magnum RC

Good Day all,

Here is another chapter as I slowly put this Spit together. I want to say that most 30cc engines will fit in the Spit without any problems and you will have a cowled in engine. I have chosen the 35cc EME because of it's growing reputation. The engine is much less money than the DLE counterpart, and it will start better, run better, and because of the schnerle porting and improved reed block design, top end is fantastic. The E 35 sits pretty on top of the engine box, but we had to epoxy the box together so I did. When I sit the engine on the stock firewall, it does not reach far enough to clear the cowl so I filled up the gap in the front of the box and made it flush in which I sandwiched together the stock firewall and two 1/4" firewall plated and glued all together and clamped into position. When I checked the distance, the engine fit like a glove and please notice just how much of the engine fin breaks thru the cowl. Consider we have to cut out that area for cooling anyway, I say we have a perfect match. Based on the weight of the plane, the weight of the engine, the power... We will have a thrust to weight ration of at least one to one. I bet the guys flying the real birds wished for such performance envelopes lol. So I fixed the fuselage vertical and set the engine on the firewall to mark the stand off locations. One does this the easiest here if you aren't a good mathematician. Since the cowl is in a fixed location, it was easy to locate the engine on the firewall to align with the cowl and spinner. Once done, I drew around the standoffs for location, then set one on the circle drawn and used a transfer punch that just fit inside the standoff then tapped the punch to locate the drilling location. Mounted the engine and we have a perfect location. Coated all wood parts with resin and let dry. On to the next step

kmtranmd

My Feedback: (71)

I like the outline of this Spit. Would love to see it fly in person.
What I'm more interested in is the big Zero at 93". Is the cowl for the zero fit a DLE/DA 85?
It would be a shame to fly a big Zero with a putt putt 50cc.
I'm definitely in a market for 85cc powered Zero.
My World Models 81" 53cc powered Zero has been retired/sold off to a club member.

Magnum RC

Hi Khoi,

You will have to call us to get the particulars on the Zero.

Magnum RC

Greetings Gents;

When it came time to permanently mount the spinner on the engine, run into a slight snag. The Spinner comes with a brass bushing to offer two mounting scenarios. I believe it is designed for electric first, then gas second. The bushing is not big enough to go around the prop bolt spindle on any of the gas engines so it has to be drilled out. The dilemma is this piece needs to be critically centered before drilling... DO NOT recommend using a hand drill. The size is 25/64". The best way to do it is to do it on a lathe, the next best method is drill press. If you haven't either of these options, find a friend who has one or hire it out to a machine shop. I am currently notifying the factory of the issue and hopefully they will take pity on those of us not inclined for this kind of work. For those of us with tools and know how, it isn't an issue. Check out the pics.

zrooster

Magnum, I'm a little unsure what you did with the firewall, and was hoping you would clarify. Are you saying you added ply to the firewall to ensure that the spinner ended up flush with the cowl? If so, why not use the washers included with the EME 35 as spacers (I used them on the motor when I mounted it to the run stand)? If that wasn't enough, why not add spacers (washers) and if the bolts are too short, just use longer bolts? Seems easier than adding ply. Thoughts?

G

Magnum RC

Hi Zrooster,

I chose to add plywood because the firewall needs reinforcing as well. The kit provides you with hardwood triangles to do this with but the stock firewall is thin for my blood. For electric option, it is just fine the way it is. For a vibrating engine, I wanted a thick firewall to add more support and be able to grab ahold of more box frame. Another reason is I didn't want to install the triangles behind the stock firewall that would get in the way of the standoff mounting bolts that have large metal washers on them. The washers fit flat against the firewall. Another reason is I didn't want to negate one of the benefits of the engine design, anti vibration casing. You will notice that the standoffs for the EME engines are designed with a large mount to firewall footprint. Installing washers increase the length of the standoffs thereby increasing the vibration factor. I don't know about how much, but for me forgoing all the above in engineering wasn't worth not extending and thickening the firewall. It really wasn't that big of a deal considering the firewall just comes out of the box so you can trace around a piece of plywood, then done. Sandwich them together and you have a good reinforced mounting firewall that doesn't need the triangles in the rear. That's my story and I am stickin to it.

Magnum RC

I have had more "how do I do this on the choke sitting against the firewall" question than I can think of... Because EME provides some metal casing at the rear of the engine, I decided to install a bellcrank hooked to the choke so I wouldn't have to run another line through the fuselage. This way, it is easy smeezy to run another 4/40 wire to the outside of the cowl inconspicuously, and have an easy manual choke to the rear carb. IF you are using any EME engine, this will be a great solution. Would anyone else care to comment on some of their ideas of how to hook up a choke efficiently to the rear carb without going through the fuse?

zrooster

That makes sense, and is one of the reasons I thought you might have gone that route...definitely no harm in reinforcing the firewall. For the choke, I've got nothing. With the rear carb, there's no easy way to set it up externally. I'm tempted to put a small servo in the nose to actuate it...

Magnum RC

Engine cooling was a scratch your chin moment. I had an idea and I launched into it. You see the Chin scoop is right in the way of an outlet at the bottom of the cowl for an engine cooling outlet. So I made the scoop functional. At least I hope I did. I carved out the inlet for the engine cooling and made everything fit. Then, I carved out louvers in the bottom of the cowl that empties into the chin scoop. I then louvered the back of the chin scoop and hope the Chin scoop inlet air causes it to create a low pressure in the cowl thereby helping everything to flow out the back of the chin scoop. If you will notice the black plastic grommet near the chin scoop mounting bolts, that is for the Ignition LED light so when you look down the scoop you can tell if the ignition is on or off. I hope this design works well and keeps the engine cool.

ForcesR

Just my humble opinion, I believe engine cooling will be a problem as you now have it! The cool air intake is to large in area than what the hot air exhaust louvers will provide in the chin scoop. Lose the chin scoop louvers, open the hole to a rectangular shape and add a dam to the leading edge of the rectangular exhaust hole on the chin scoop and you may get sufficient cooling.

Roger

zrooster

Can you post a pic that shows how much you opened up the cowling in the front? Was it necessarily for clearance or just cooling?

Magnum RC

Thank you Roger, Like I said, it is a scratch you Chin idea... I know the formula for intake verses out on engine cooling, but I wanted to minimize the gaping holes in the cowl as much as possible. I am actually counting on the opening in the chin scoop with the flow entry and exit to create a lower pressure area to "suck" the air from the cowl through thereby making up for the gaping holes in the cowl. The louvers help retain the integrity of the fit of the cowl considering it makes a difference on the bottom end since you can't anchor the cowl to the fuselage down there. I, quite frankly hope your wrong; I am going to test this design and see if it works to keep the engine cool. If it doesn't work, I will adopt your suggestions somehow and figure out how to reinforce the bottom of the cowl for that fit I am talking about. I think one fellow put it in your face on another thread, "Here we go again with trying to air cool an air cooled engine in an airframe designed for liquid cooling" Wouldn't it be very cool if the engine designers would come up with an efficient and compact method of liquid cooling. I think it would be rad to actually fill the radiator housings with radiators.

Magnum RC

Here you go Z, this is better picture of the front of the plane.

zrooster

Thanks! It looks (from the picture) like the only thing you had a clearance issue on was the plug/cap. Obviously you need an opening for cooling, but I'm thinking if I could make a blister to clear the spark plug I could get away with a slightly smaller hole for cooling which wouldn't be too bad...

How do you gauge the effectiveness of your cooling set-up? Do you have a way of reading the temp on the motor?

Magnum RC

Well Z, I have one of those fancy radios, the Futaba 14SG with Telemetry. This plane is certainly a candidate for the engine Temperature sensor as will be the P-51 when I get it. The Temp of the engine will be transmitted back to my radio as well as air speed, or altitude, or RPM of the engine, or even the fuel tank level... Hmm, we've come a long way baby...

As far as the intake, perhaps you can.. I would make sure it is well broke in before I close it in like that. Like I said, this cooling design is an experiment and the blister for the plug is a great idea, it doesn't need much to close it in.

zrooster

Nice! I think one of my radios might be telemetry capable...might be the way to go. Having an idea what kind of speed you're flying on final is a nice backup too. Though Im taking a 2 month hiatus to learn how to fly the mighty 747-400 down here in Miami right now, I've still got my run stand all set-up back home and should have the motor nice and broken-in by the time the model is ready for it!

I'll mess around with it when I get model in hand (or get my hands on the model) and post what I come up with on here.

zrooster

Just ordered two 4 blade props for possible use with the Spit. A Biela carbon fibre 16-8 and a Zinger wood 17-8. Based on what I've been looking at, those should work. When I get home in April, I'll throw them on the run stand and see how they stack-up! Now I just need to find a 4 blade spinner that works!

mark IX

My Feedback: (9)

Magnum Rc, what is the status on the new 88" P-51 Mustang?

Mark

dgiatr

Magnum Rc, did you need any extra weight to balance the plane to the indicated center of gravity;

mups53

My Feedback: (41)

http://www.gator-rc.com/spitfire
Hi I'm Mike Mueller owner of F3AUnlimited.com and now Gator-RC.com
I wanted all to know that the first shipment of the 5th scale 81 inch TopRCModel Spitfire is now for sale. Gator-RC.com is the North American distributor for this brand.
The shipment is scheduled to arrive here in about 4 weeks at which time we will start sending to the customers.
We have a very limited amount coming. Reserve yours now.
Thanks and have a great day.
Mike Mueller
Gator-RC.com
800 380 9373
Also pictures of what will be available later this summer. The new 5th scale Jap Zero 93 inch WS and P51D 89 inch WS.

flypilot

I am really loving how tha Zero looks, any chance you ( Mike ) could get some more pictures of that plane, maybe a sideview and a view through the hatch? Also cowl measurments would be appreciated as I have a Saito FG-60 that would be perfect for this plane if it fits?..
Thanks...

mups53

My Feedback: (41)

Hi I'm working to get better pictures.
Thanks the plane is better in person. I real beauty. Mike
Gator-RC.com
[email protected]
800 380 9373

mark IX

My Feedback: (9)

Mike, can you get better pics of the Mustang while you're at it? Is that the 88" ws model that was also going to come out this year?

Thanx, Mark

flypilot

Thanks, much appreciated, do you have the retracts for this model as well? Pictures?

Thanks again.