SWORDSN

My Feedback: (13)

You are probably right Bob.

Thanks

B-Squared

I just bought a Saito 450 for my corsair which does fit in the stock cowl...this was after looking at what I thought was every gas twin out there. Same result...the plug caps were always a bit too wide for the cowl. The day after I bought the Saito my buddy stumbled across an add on RCGroups for a Fuji BT-86 twin, new but discontinued. The plugs are angled with a distance of 252mm (9.92"). On the Fuji website it says it can swing up to a 26x10 prop. As of this morning it was still there...the guy sounds motivated to sell it.

SWORDSN

My Feedback: (13)

It's my understanding that parts are no longer available. That makes it risky, but it's worth considering.....thanks

Thunderbolt47

My Feedback: (8)

Never been a big fan of fuji engines

SWORDSN

My Feedback: (13)

I guess there is a reason that they are discontinued!!!

rt3232

My Feedback: (6)

Hi Guys

One of our club members has had a coupl of the fugi's but not in war birds and they seamed to run great , good responce etc, the reason he used them was becouse of there weight and the short nose moment on his birds. I don't know if he has ever tried to get parts but to the best of my under standing they have never been crashed or in the dirt so to speek

Cheers Bob T

mrrandyman

My Feedback: (3)

I would suggest sticking with a current engine. What may seem like a good deal now could lead to nothing but headaches down the road.
The saito 450's that I have seen in a couple Corsairs work great but the fellows did mention a problem witha bearing burning out on themso that might be something to look into further before making a purchase.
I know either way I am going with a Radial in the one I have on the shelf waiting to be built.
This one will also have folding wings . I have enough info on that part so I am going to do some work on building a unit that I will eventually be able to offer to anyone that wants one without breaking the bank.

ya33a

Hi,

I know the Saito R325 fits inside the white cowl, (I checked it out at my LHS), would it be enough of an engine for this bird? I think it pulls about 18lb to 24lb static, on the 22x10 prop.

glazier808

My Feedback: (1)

That Saito 325/5 does sound nice...here's one in a zero(11kg weight I believe)


Casey

mrrandyman

My Feedback: (3)

Here is a youtube vid with the 325 in it.
http://www.youtube.com/watch?v=xZTm3ZSoeDw

straitnickel

I moved the firewall back 2" and used a G62 and mick reeves prop reduction on mine. But will still be awhile before it gets finished.
Just saying

rt3232

My Feedback: (6)

straitnickel

Would like to see some pic's of that set up on the reduction

Cheers Bob T

Fly2XS

My Feedback: (65)

This is directly from Mick's Web site:
http://www.mickreevesmodels.co.uk/~m...ccessories.htm


TORQUEMASTER £195 (roughly $320 @ 1.63$/£)
SPEED REDUCTION UNIT for ZENOAH 62
50% Thrust increase, from 20lbs for standard Z62 to around
30 lbs when fitted with Torquemaster.
1. Bolt-on Unit. no modification to the engine.
2. More torque drives bigger props for increased thrust.
3. Moves the thrust line closer to the centre of the engine.- Easier cowling.
4. Ratio 1.75:1
Thrust - 30 lbs. Weight - 2¾ lbs. Length increase - 2½ in.
Prop shaft is 75 mm above engine shaft. Pulley runs on two ballraces.
Prop .........RPM A well run in engine can give 10% higher RPM.
26 x 8 ......5400 (prop too small. Suggested max RPM - 5100 on prop.
26 x 10 ....5200 (a bit small)
28 x 12 ....4600
28 x 14 ....4400 (takes my 1/3 Camel up vertically!)
30 x 11 ....4000
32 x 12 ....2700 (too big for max power)

This looks like the right size to drive a scale appropriate 26" (3) blade prop on the Corsair!

Here's Mick Reeve's Chat on the TorqueMaster on the G62 (From his web site):

TORQUEMASTER for Zenoah Titan 62
This unit bolts onto a Zenoah 62 engine and provides a belt driven reduction drive to a new prop shaft set in front of the cylinder. This enables a larger propeller to be driven, which is more efficient and gives greater thrust.
Why is a Reduction Drive needed and what advantage does it give? This is a difficult question to answer fully but a simple analogy will help. It's rather like the gear box on a car. Try pulling away in top gear and you will find that it is a great struggle and acceleration will be very slow until you reach a reasonable speed when the clutch can be fully engaged and the car will then accelerate to high speed. This situation can be compared to an engine fitted with a small diameter prop, or ducted fan or turbine. Acceleration from rest can be poor but performance is good once a high speed is reached.

The propeller or fan in this case is very inefficient at low speeds. Most of the energy is wasted in turbulence behind the model. Modern ducted fan models overcome the slow acceleration problem by using a very powerful engine, perhaps four times the power used in a similar sized propeller model.

The opposite case, pulling away with the car in bottom gear gives very good acceleration from rest but, of course, the car will not go very fast. If you are pulling a very heavy trailer uphill then bottom gear might be just right for the situation. The equivalent case for a model aircraft (or full size aircraft come to that) is a large, heavy, slow flying machine, where a high ratio reduction drive could turn a large prop to give the thrust needed to fly the model. But you don't get this extra thrust for nothing - the theoretical top speed available will be proportionately lower, although the model can actually reach a higher speed in practice because of the improved efficiency.
Most large scale models would lie somewhere between these two cases and most of these would benefit from using a reduction gear.

Propeller efficiency. This concept is rather difficult to explain. The propeller thrust must equal the drag of the model at a particular speed and the thrust is obtained by the propeller throwing back a column of air faster than the model is flying. The thrust is calculated from the mass of air x change in velocity.(MV) Therefore, a large prop, moving a large column (and mass) of air, can throw the air back at a low speed to achieve this thrust, whilst a small prop would need to provide a much higher speed column of air to get the same thrust. The difference between the rearward speed of the air from the prop and the forward speed of the aircraft is referred to as propeller slip and the greater the slip, the less efficiency.

Mathematical explanation:- Thrust is given by M x V , BUT the energy lost in the slipstream is given by 1/2MV2. Work it out and you find that the smaller prop with higher velocity change has much higher losses for the same thrust.
Deciding on whether a particular model would benefit , and deciding what prop size would be appropriate, is quite a problem. It is possible to calculate this provided all the facts are known but normally we do not have enough information available to make calculations worthwhile. You would need to know the speed and drag of the model; the torque curve of the engine; the thrust and torque absorption curves of various props etc. A more practical way to decide is to look at existing models which are successful with the standard engine and then look at slightly larger heavier models which can fly on the straight engine but where the performance is marginal during takeoff and climbing. This is where the torquemaster can be a real benefit. My 1/3 scale Camel is 112" span and weighs 3Olbs. The King 100 engine used in this model turned a 28 x 14" prop. at 42-4400 rpm. This gave good performance but fitting the Zenoah 62 and Torquemaster resulted in an extra 200 rpm on this prop and vertical performance with the much smaller engine.

A rule of thumb for deciding what propeller pitch to use is to aim for a 30% propeller slip. So if the model is flying at 40 mph it will require prop pitch equivalent to 57 mph ( 40 /0.7) At 5000 rpm this needs 12 inch pitch. ( MPH X 1056) RPM One would then adjust the prop diameter to reach the required rpm. The Manufacturers' power graphs for the Zenoah 62 suggest that maximum power is 4 BHP at 8500 rpm (silenced), and my engine appears to run quite happily at 9500 rpm. If you want maximum performance then you should select a prop which will allow the engine to reach these speeds, but a bigger prop might be preferred to reduce noise, engine wear and fuel consumption. My approach with the Camel was to prop for around 8000 engine rpm at full throttle, giving near maximum power but only using full throttle very rarely in flight. Level flight requires only 1/4 throttle and scale aerobatics can be done on about 1/2 throttle. It's nice to have the extra performance in hand for use when you want it.

I believe that use of the Torquemaster will give great improvements in models over 25 lbs and will give the impression that a larger engine is being used. Takeoff runs will be much shorter, climb outs can be steeper with good control authority, where using the standard engine would have meant a struggle to get airborne and a slow climbout near the stall.

rt3232

My Feedback: (6)

Hi Scott

Thamks you rascel, but I would still like to see just how he is doing it, so this old man can learn some thing

Cheers Bob T

ya33a

Hi,
I appreciate the information, that makes the decision a lot easier.... I will look at getting my Corsair as soon as I can scrape together a few more $$$...
Thanks..

mrrandyman

My Feedback: (3)

Post a few pictures of your build showing the placement of the firewall.
Personally I think a drive unit on the topfite kit is overkill. I could see using one on a much larger model.

Me410

Hi all, my Corsair is almost complete and will fly this Spring, I will post pictures then.

Quick question.

I will be powered with a G62 swinging a Xoar 22 X 10. I started to put in a 20oz fuel tank, now I am not sure if that will be large enough?
This is my first "gasser" , so not sure on fuel consumption. I do like to fly at full throttle alot.
Anybody using a 20 oz, and how long are your flight times?

Thanks
Tom

rt3232

My Feedback: (6)

Me410 Aka Tom

20oz. should be more than enough, but it all depends on how long you fly ie: my 62's burn about 1.5 oz per min and that gets me 9+on a 16oz tank, but I normaly fly about 7 to 8 and I am on the ground by 9

Hope this helps

Cheers Bob T
AMA 13377

Chad Veich

My Feedback: (60)

I would love to hear anyone's experiences with the Mick Reeves drive unit. I have pretty much settled on acquiring one for my 1/6 scale Hellcat with the hopes of running a near scale diameter 3-blader. There's not a lot of information out there from folks who have actually used the unit in an airplane. Maybe that should be telling me something! [X(]

Me410

Thanks Bob, I feel better about the 20 oz tank now.

Chad
I don't know anything about the Reeves drive unit , but if the aim is to run a near scale 3 blade prop, electric works great.
My next project is a Platt Me109, and I will be using a Scorpon 5525-225kv motor spining a 20x12 3 blade prop, with 2 6cell lipo in parallel.
That prop size is about an inch withinscale.My buddy hadthat same system and it worked great, even sounded good.
BTY, did I read thatyou had scale exhaust stubs for thatmodel?

Tom

glazier808

My Feedback: (1)

I agree, electric will allow you to spin a good sized prop.  I'm using a 20" four blade variable pitch from varioprop on my 1/6th scale P47.  There are some really great electric offerings now in the larger sizes to choose from.  

c550

My Feedback: (16)

I am working on mounting the engine to the firewall. I am going to be using a Saito 450 and I just figured out that the center of the firewall is not the center of the fuse, so I will have to lower the firewall by about a 1/2 inch. Anyone else run in to this. Also if anyone used a Saito 450, what size fuel tank did you use.

P47flyer

My Feedback: (6)

Did not have to lower firewall.just relocated mounting point to center crankshaft. I'm using a DuBro 1500 cc tank (50 oz.) and it is good for about 12-14 minutes.

Dave H.

mrrandyman

My Feedback: (3)

Post some pictures folks.

B-Squared

Hey c550...Just in the process of mounting a 450 on my Corsair...I've been doing a lot of mods along the way, including the firewall. I'm going to use a 32oz. tank. I think that will work well but I'm not sure...As to the firewall, I took out some of the right thrust, added 1/4" ply around the outside of the firewall box, made a 1/2" ply "plug" for inside the firewall box and faced it with a piece of 1/4" ply. I'm going to glue it as well as pin it to the fuse when all is said and done. I didn't move the firewall at all...once I marked the horizontal and vertical I marked (according to the Saito manual) where to drill the holes for the mounts. I did move the mounting holes 6mm to aircraft left to account for the right thrust. If I was more computer savy I would post the link to my build...anyway its the Top Flite GS Corsair - Plug in Wings thread.