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mobileraptor 06-04-2004 06:20 PM

RE: Balsa USA enforcer
 
1 Attachment(s)
Hi Joe

I traided a few e-mails with you a month or so ago (Evon Smith). My project is going well, My only hold-up right now is I'm waiting on the nose strut. don't want to close up the bottom of the fuse untill I have the in an working properly.

I did a few mods myself, I turned the turtle deck (area behind the the canopy) into a full length hatch, also the cockpit/canopy is a removable hatch and I have another hatch under the nose incase I have to add balancing weight to it.

Pretty much made up my mind to make this a one peice airplane, since the engine is no longer part of the fuse I don't want to mess with having to disconnect fuel line and linkages to split the airframe, another reason for all the hatches.

Fuel tank is 24 oz mounted on it's side (only way it would fit) with a 4 oz header tank. 28 oz should keep it in the air for a little while.

One other minor mod, a aluminum hubbed Carbon Fiber bladed high per fan, should be good for another 2 to 3 lbs of thrust!!!!!!!

CARS II 06-04-2004 11:20 PM

RE: Balsa USA enforcer
 
1 Attachment(s)
Here is one of my convertions.

CARS II

Andrew Ditchfield 06-06-2004 09:13 PM

Engine Sags on Balsa USA Enforcer
 
I put a OS .91 Surpass in mine, but it often sags at high throttle. Since the tank is in front of the engine I ran the fuel lines out the tank and then back along the outside of the tank back to the firewall and engine. I did this to keep the tank in the normal orientation so that the clunk would be at the back/bottom in a nose up attitude. Now I wonder if my fuel lines are too long or if I need larger diameter tubing? Has anyone had this type of problem with a pusher plane?

mobileraptor 06-07-2004 10:01 AM

RE: Engine Sags on Balsa USA Enforcer
 
Hello Andrew

One of the problems with the pusher designs is engine cooling, with the engine mounted in the front of a plane you not only get the cooling of the air the plane is moving through you get the prop wash moving over the engine which is a lot of cooling power. With the pusher design you only get the air the plane is moving through.

More than likly, your engine is getting to hot in flight. As the engine temp go's above it normal operating temp the engine timing changes, this is caused by the inside cylinder temp causing the fuel to combust before it's suppose to which mean even more heat.

There are a couple of things you can do to correct this, first of corse is to richen the engine a few clicks. This not only put more fuel in the engine, it put more oil. Second is to add more oil to you fuel or run fuel with a higher oil content.

Many people don't realize that it's oil that cools these engines. Oil transfers the heat from the internal moving parts (Pistons conrods, valve train, crank shaft) to the stationary parts (Cylinder head, cylinder and crank case). It also carries some of the heat with it out the exhaust.

Fuel with a blend of syn/caster has better cooling, when a engine overheats the synthetic becomes somewhat useless because it's beyond it operating temp, the caster will take over, coat the moving parts and keep the engine from destroying itself.

Many people will hear an engine bog in flight and think the engine is not lean enough so they turn in a click or two and the problem gets worse, why it's already to hot and by leaning the engine it's getting hotter.

I don't know what fuel your running so I can't advise about that.

Hope this help you.

:D

livinabox 06-07-2004 11:30 AM

RE: Engine Sags on Balsa USA Enforcer
 
This has kind of answered a question i had in mind for the future as iv not got as far as to fitting the tank and id wonderd the other day if it goes the other way round or the normal way with a rather long pipe. Im not happy about the idea if this is the case and would be tempted to go the "Larger Bore" route just in case.

Nothing worse than a flame out when pointing upwards and low at the same time.

The comments on the oil were so true regarding the heat factor ...and we even play around with 4% water added some times to improve the power ...works most of the time!
Lucky for me iv a scientist/chemist who makes his own fuel and advises me on stuff like that.

Andrew Ditchfield 06-07-2004 01:21 PM

RE: Engine Sags on Balsa USA Enforcer
 
Thanks for the reply. I will try to richen it a bit more. I also suspect the tank may be a bit high which makes it appear to be running rich at idle, but then lean out at full throttle. I already lowered the tank about 1/2 inch which seemed to help. I may need to lean out the idle adjustment and richen out the top end. Did you have to run the fuel tubing out of the tank and back along the length of the tank to the engine? Did the long length of fuel line cause problems?

mobileraptor 06-07-2004 01:50 PM

RE: Engine Sags on Balsa USA Enforcer
 
The plans call for a 10 oz tank which is a joke for my application, an OS-91 DF engine will blow through 10 oz's in about 4 min.. Thats enough to take off and glide. I'm installing a 24 oz tank with a 4 oz header tank which come out to 26 27 usable.

I'll be installing my tanks in the normal fashion but I will use a tubing bender to make two 180 radious bends were they come out of the tank. This way the fuel tubing will make a straight shot to the engine with out have to make any bends that might kink the lines.

Larger fuel tubing on the supply line should be OK but I wouldn't put it on the muffler pressure line. the extra surface area inside the tubing will absorb some of the line pressure.

marwen1 06-07-2004 02:03 PM

RE: SERVOS
 
MOBILRAPTOR

If I'm not mistaken, I think I have seen that you install your servos for the ELEVONS & the ELEVATOR somewhat near to the actual element itself. Question: How do I make the linkage to the horn(s)? Also, how do I make the ELEVONS function i n the PUSH/PULL configuration without the use of the usual rods?nI

mobileraptor 06-07-2004 04:10 PM

RE: SERVOS
 
I did use a pull-pull system on the elevator on a 40 size Shrike. I think I wrote about it in one of the shrike threads. Basically you turn the servo on it's side, inside the wing as far back as possible. Then you use a oversized two sided control horn so it will pertrude out either side of the wing and runs in a slot.

The trick to this is the distance between the two holes on the control horn and the distance between the two atachment points on the surface have to be identical.

There are two type of controls of this type, one is pull-pull the other is push-pull.

Pull-Pull

Pull-Pull uses cable, usually nylon, kevlar, steel or stainless. There is an adjuster on both cables, usually a threaded rod with a clevis on one end and a hole drilled in the other for the cable to go through. The cable is attached by threading the cable through a small steel sleave then throuh the hole in the threaded rod and than back through the sleave. when everything is spaced properly the steel sleave is crimped to lock the cable into it. Ajustment are made by screwing the clevis on the threaded rod.

The reason this is call pull-pull is the cable pull the surface one way and the other cable pull the surface the other way.

Push-Pull

Push-Pull is simiular to pull-pull except it uses a linkage rod (Heavy Wire) with threads on one end like comes with most kits. one end is already threaded for a clevis, the other end is usually "Z" bent to go into the control horn. some people will solder a threaded coupling on the "Z" bind side and have a clevis on botf ends. If you put a clevis on both ends one must have some type of lock to keep the rod from turning.
Sence the wire is solid one pulls the other pushes, hence push-pull.

Each have there advantages, you can do long runs with the cable in a pull-pull system, the servo can be several feet from the surface it is controlling. But you have to keep them adjusted for any stretching that may take place. Push pull is good for short distances and puts very little load on the servo bearings.

CARS II 06-13-2004 03:31 PM

RE: SERVOS
 
1 Attachment(s)
Mobilraptor, Mark. Here are the first pictures of my Enforcer so far I have the turtle deck build up far enough, next is the wing, every thing is been build as per the instructions for now, once I get the basic frame build up I will be adding the engine mount, servo mounts, mechanical retracts I have a pair that has been laying around for a while so it's time to put them to use, the nose fuse will be glued to the wing to make this a one piece airplane, the nose retract a mechanical also will be actuated via a cable connected to the mains servo, I'm looking to install a 20 to 24 oz. fuel tank as I will be using a K&B 7.5 on this airplane because of that I will try to keep it light as much as I can, the turtle deck will be cut to half to accommodate the fan/engine just over the CG to keep the airplane balance and I like the idea of been able to remove the vertical stabs for transportation like this I could put it against the roof of the Cherokee.

CARS II

CARS II 06-13-2004 04:10 PM

RE: Balsa USA enforcer
 
Hey guys check out this Enforcers, go to the jet forum then go to DFW jet Rodeo thread then go to the last page there is a web address posted with 200 pictures of the event, there are some good pictures of the two enforcers that attended the event, get some ideas how to build the elevons or not.

CARS II

mobileraptor 06-13-2004 04:52 PM

RE: Balsa USA enforcer
 
1 Attachment(s)
Well, She's on here wheels!!!!!!

Dash7ATP 06-13-2004 05:08 PM

RE: Balsa USA enforcer
 
Looks Great!

Joe

CARS II 06-13-2004 08:37 PM

RE: Balsa USA enforcer
 
Looking realy good, don't let me catch up.

CARS II

wled123 06-15-2004 11:22 AM

RE: Balsa USA enforcer
 
1 Attachment(s)
The Sunspot appeared in the August 2002 issue of Flying Models, page 66. Complete construction details and conversion plans from the Force One to Turbax ducted fan power.

Bill Yonescu 06-17-2004 04:16 PM

RE: Balsa USA enforcer
 
1 Attachment(s)
It looks like this post was born after I got my Enforcer.

Great Plane!! I have a Tower (yes, Tower) .75, std muffler and Cool Power 15%. It turns an APC 11x7P at 14,500 RPM on the ground. It probably goes a little over 100 mph in level flight. I have but haven't tried the APC 10X8P. Soon. It will be a bit faster and a bit noisier.

I cut 2" off the recommended height and used Hobbico retracts. Did have quite a bit of a problem taking off until I added castor to the nose wheel.


Great Plane!

Bill

CARS II 06-17-2004 10:31 PM

RE: Balsa USA enforcer
 
Bill thank you for showing us your Enforcer I like the colors.
I'm back home after along week of work away from home, there were many times I found my self day dreaming about the Enforcer and the changes I'm going to do to it, I'm giving my self a month to complete this airplane, soooooooooooo tomorrow is building and building time.

CARS II

ram3500-RCU 06-18-2004 01:52 PM

RE: Balsa USA enforcer
 
1 Attachment(s)
Here is the latest one i built (and sold). It has an older but never used OS MAX 90 in it. It fly's great. I had one i put retracts in that had a ST 75 and it was VERY fast.

livinabox 06-18-2004 03:43 PM

RE: Balsa USA enforcer
 
nice piccys and i want more please guys as it gives you more ideas.

Do these things really do a 100 mph on the flat i wonder?
With a 75 i find it a bit doubtfull but who am i !!!

Owing to the fact that the OS engines now are getting slagged off as to thier
quality im a tad concerned that i should get one as iv 2 90 size Tigers sitting around but the tuning on them is a pain in the butt. The 75 which was in my
"Panic" is shelved as it was such a pain to keep going. But having said that
the larger ones in the 2500 3000 range are a gem to run and start real easy.

Stop the clock i dont want summer to end!!!
Regards to all ...Steve UK.

CARS II 06-19-2004 01:03 PM

RE: Balsa USA enforcer
 
Tigers like to be run with almost no nitro.

CARS II

livinabox 06-19-2004 01:10 PM

RE: Balsa USA enforcer
 
i dont run nitro in any engine unless its well below zero ...the mix we use is just plain old methanol with ML70 at around 15%.....Works on everthing i own....other than the smaller cats.
We do add petrol in the colder weather as well ..and some times a tad of water (long story)

Keep em coming .....piccys by the bucket full pleeeeease!!!:D

mobileraptor 06-19-2004 02:25 PM

RE: Balsa USA enforcer
 
1 Attachment(s)
I received an E-mail


Dear friend:
Do you have the plans of the Balsa USA Enforcer Extend Fuselage?
Can you sell me a copy. Please inform.
Thank you'
I decided to respond to it here just in case someone else wanted to know.

First off there are no plans for extending the enforcer nose, the procedure is know as kit bashing.

The way I did it is pretty simple, I tape together a couple of sheet of printer paper and then taped it it down over the plans with about 8 inches of the paper to the front of the nose. Note there is a center line reference on the side view of the fuss, now draw the flat of the front of the fuss side the desired distant forward of the nose using the center line as a reference.

We now have a point where the new nose is going to end, Now draw a line from the top or the new front nose line to where the plywood side kicks down to start forming the nose. Now do the same thing on the bottom with the line starting at the bottom of the nose line and ending tat the bottom of the wing saddle. With that done now trace in the stock plywood from the plans to the paper.

You now have a template of the new peace you have to cut out to extend the nose, Remember you need two of these, so make a copy of the one you just drew or you'll be doing it again.

Sand for a perfect fit and your ready to join the parts. I join the parts on top of wax paper on top of a glass surface. Once this is done you install all the 1/4 inch stock as called for in the plans but follow the new edges. Also the bulkheads will have to be spaces different to match the new nose.

The reason for the nose extension is to counteract the weight of the ducted fan and fan nacelle so if your trying to do this to a stock pusher Enforcer your going to have to come up with some tail weight to balance it. Also all my control surface servos (4) are about 4 inches fwd of the trailing edge of the wing which puts them aft of the CofG Instead of Fwd of the CofG as the plans call for.

So the whole point of the is to help balance the plane.

The plus side of this is the plane looks much better too. :D

Below is a picture of the completed nose extension, You can easily see the difference between the stock lite ply side and the new balsa.

mobileraptor 06-20-2004 09:18 PM

RE: Balsa USA enforcer
 
1 Attachment(s)
Well, Been busy this week, But got a little more done on the Enforcer.

Air Tank, Retract control valve and servo and air lines are in.

Fuel tank is set up.

and finally the mixture and throttle control servos

livinabox 06-21-2004 03:38 AM

RE: Balsa USA enforcer
 
Being a big vague here but what is the "Mixture" servo for? And does the clunk being bent round like that work with such a long distance for the fuel to run to the lump? Do you also need slightly larger tubing for the 90 size engines?

The build goes on.

mobileraptor 06-21-2004 11:54 AM

RE: Balsa USA enforcer
 
My OS-91 has been modified to have an (In Flight Mixture Control). This allows fine tuning of the engine in flight by using a knob or side slider switch on the radio. Remember most DF engines are inside some sort of ductwork and getting to a normal needle valve on the engine can be a chore.

Someone once told me the magic number is 12 inches. I don't know the why or wherefore of it, it was just something I was told.

I've been thinking about various things concerning the fuel system. I can fill the (24 oz tank) with a pump 1n about a minute, so the std size fuel line can flow 24 oz of fuel under certain conditions. (I.E. Pumped) I have estimated the fuel consumption rate of my OS-91 to be between 2.5 to 3 oz per minute. My next test was I filled the fuel tank half full I blew into the vent line (mouth pressure) and not blowing that hard I could flow 6 to 7 oz in a minute which is twice the flow I need. So fuel flow with standard size tubing should be no problem.

Now to the brass fuel tubing, The inside Diameter (ID) of the brass tubing is the same as the fuel line so the flow should be the same. Fluids don't like flowing through sharp corner like a 90 degree bend, but as long as the bend is on a radius flow is smooth.

One other thing is the carb also draws fuel (Sucks) using the engines internal vacuum, so the exhaust tap pressurizes the fuel tank and the engine sucks :D A good example of this is a loss of the muffler in flight. Saturday my muffler came loose on my helicopter while in flight, it's easy to notice due to the sound and change in engine rpm. At this point all tank pressurization is lost and the engine is now sucking fuel. I reduced throttle to the minimum (Because I know the engine is running very lean) to keep it in the air and brought it in a landed it.

I don't have a degree in any of this so I can't give a Egg-head explanation, but everything should work with no problems.

Here's another though, the cylinder of a .91 is of course .91 cubic inches, at 24,000 rpm (ducted fan engine speed) that is 21,840 cubic inches of volume out the muffler in 60 seconds or 12.7 cubic feet per minute. Now if I only knew the math to calculate the back pressure of all that going through a 3/8 inch hole we'd know approximately what kind of pressure we'd have on the tank. :eek:


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