Author Topic: Primary Force (Read 4534 times)

RC Storick · « **on:** February 08, 2006, 04:57:32 PM »

This was posted on SSW by Steve Scott.

Pictures to come soon but I just picked up the ARF at my trusty LHS for $134.95. A bit more expensive than the current crop of ARFs but here are my initial observations:
Technical Specifications
The PF is not a large airplane but larger than the Top Flite ARF Flite Streak.
- Span = 50.8"
- Area = 500 sq in
- Length = 39.5"
- Est. weight = 36-40 oz.
- Recommended engines = .25 - .40. They suggest the Fox 35 Stunt, OS LA/FP 25, Norvel Big Mig 25 (shown in the illustrations), OS 35S, McCoy 35 Redhead (no longer in production but available on the "bay"), OS LA/FP 40 and Brodak 40. The emphasis is on a lightweight 2 stroke in the class of the Fox 35. I saw Bob Brookins fly a PF couple of years ago with a modded Fox 35 and it did quite well.

Packaging
Typical for an ARF, all individual components bagged in plastic and bags taped to the box for minimal shipping nasties. We opened mine for inspection at the LHS before I paid for it. It was pristine.

Components
- Fuselage - wing and stab cutouts precision laser cut. Vertical stab already assembled and attached to fuse. Wooden canopy trimmed in silver and black film. There is some type of approximately 1/8" wooden pads to mount the engine. Assembly is light and very straight.
- Wing - one piece with access hatches for bellcrank and tip weight box. Adjustable leadout guide. Covering applied so little or no trimming is required to glue into the fuselage. Cap strips and radiused corners for the sheeted center section. Again, very light and very, very straight.
- Elevator/stab already joined (dry) with wire joiner, hinges slotted and dry fit. Slotted CA hinges included. I intend to use the supplied hinges.

Hardware
- Aluminum dural LG
- Main wheels w/tube bushings
- Tail wheel and wire
- Pushrod wire, threaded metal clevis on elevator horn end w/retainer spring & lock nut
- Nylon elevator control horn and retainer plate
- Metric screw fasteners
- 1-3/4" white plastic spinner
- Kavan 4oz plastic rectangular clunk tank
- J-bolts (4) for tank mounting
- Assembled 4" bellcrank (reverse), fairly thick gauge aluminum but with lightening holes on the arms. Horn is offset and comes with a bolt mounted R/C type connector for elevator pushrod (retained via set screw). Leadouts are double looped and crimped. Leadouts unfinished on handle side but come with eyelets and crimping tubes. Assembly appears to be non-removable with post type pivot.
- Covering is Sig's Aerokote in Bright Orange and Brilliant White. Very well applied, no wrinkles sags and only one bubble on the white trim I've found. I could see a 5/16" overlap on the LE seams so should be no issues with fuel seepage. I'd be hard pressed to do a better covering job.

Best feature I've found so far is the typical Sig superb assembly manual. This has an abundant supply of high quality illustrations, has tips for selecting props, line sizes, suggested lap times and very detailed at how to plumb the fuel tank for standard outboard mounting and inboard vents. Also appreciated are starting amounts for tip weight, Leadout position, CG, line length and handle spacing.

So far, I believe this is the highest quality C/L ARF released to date. It is a very competitive design and a killer for the P-40 event. This one's gonna get put together and flown before my other stack of ARFs get done!

Steve Scott · « **Reply #1 on:** February 17, 2006, 12:23:26 PM »

I've started assembling the Primary Force and can make the following additional observations:

The fuselage is laminated with 3 cores of balsa - each slightly less than 1/8" thick (overall thickness is 1/2"). It's light enough to ascertain the likelyhood it is not solid all the way through.
Slots for hinges are already slit in elevator & stab. The joiner wire area already is grooved and a hole drilled where the pointed ends of the joiner slide into the elevators.

Overall a very well engineered ARF. I will start out with an FP .25 for power using a CNC machined tongue muffler and 9-4 APC or Grish prop. Likely Sig 20% Champion fuel.

We're getting our first sub-zero weather here this weekend - otherwise I'd be out flying something.

Big country Joe · « **Reply #2 on:** February 23, 2006, 05:27:15 PM »

I got mine Tuesday. I am really impressed with the whole range of well thought out methods and parts as they come. Just wish there were more colors, but plan on adding a bit of blue someplace as all my recent planes reflect an orange and blue motif (old school colors and all that). Well wotrth the extra few dollars. I got a call from my ex business partner in the East and listening to me describe my "Force" he went out and got one for himself yesterday. He too is very very impressed.
JJ

wwwarbird · « **Reply #3 on:** March 08, 2006, 05:54:51 PM »

Sparky?.......ARF? Whoah.

jeffindayton · « **Reply #4 on:** May 10, 2006, 05:56:54 PM »

How much do the parts weigh?.........

When do we get to see the pictures?

??

Show us the stuff man!!!!....I just signed up for Stunt Hanger and I am already getting strung out.....

Droolingindayton
er ah

jeffindayton · « **Reply #5 on:** May 11, 2006, 07:09:16 PM »

What did you end up with for the final weight? less than 50oz?

Do you think a 25 could pull it through all the manuvers on ~52' lines?

Gluing in wing...thats Ironic...

sounds like you got her down ok..

Thanks
Jeffindayton

Leester · « **Reply #6 on:** May 12, 2006, 01:40:19 AM »

As stated above the projected weight is 36-40 oz. Here's 2 pics for you don't know his final weight. The secound one is stock with a Fox 35. Number one has 1/2" cut off the nose for balancing.

jeffindayton · « **Reply #7 on:** May 12, 2006, 02:28:16 PM »

Thanks guys!

It sure is pretty....I think I has to get me some plans or the ARF...I have never had an actual ARF....Seems like a excellent deal for the money....and not much hassles. Is it very similar to the Pathfinder?

still drooling for photos of the package as it comes out of the box...

oops did I just say that?

Leester · « **Reply #8 on:** May 13, 2006, 04:11:18 PM »

Jeff: I know this thread is about the ARF, but Mike Pratt the designer sells a kit version of it for about 1/2 the cost of the ARF. Sorry I don't have his web address but I'm sure someone can get it for you if you want.

jeffindayton · « **Reply #9 on:** May 13, 2006, 07:02:05 PM »

Yea....I did see that as I browsed the net...@20 for plans....

I think I would try the ARF it really seems well received the OS25LA-S came today all in good order

Thanks for all the great input
jeffindayton

Tom Dugan · « **Reply #10 on:** May 14, 2006, 01:19:05 PM »

I would like the kit form if available. I tried to contact Mike Pratt by email address in PAMPA memberslist but the address doesnt work. Anyone know more about the Primary Force in kit form or how to contact Mike Pratt?

Thomas

Leester · « **Reply #11 on:** May 14, 2006, 02:48:58 PM »

Thomas: I have the kit let me dig out the instructions since mine is a short kit. I'm not sure if he does a full one or not. I'll also look for his web page.

Leester · « **Reply #12 on:** May 14, 2006, 03:19:45 PM »

Thomas sent you a PM.

Tom Dugan · « **Reply #13 on:** May 14, 2006, 06:43:22 PM »

Got it Lee...thanks. You da man!!

Lyle Spiegel · « **Reply #14 on:** May 30, 2006, 06:37:10 PM »

Primary Force kit info see
http://www.mindspring.com/~mikeypratt/pforcemain.html

Alan Hahn · « **Reply #15 on:** June 04, 2006, 06:39:37 PM »

Here's my review of my Primary Force Arf.

Ready to fly and built stock, except for:
1) Left off wheel pants--I fly off grass field and didn't want mine to be a "Taxi Queen" like Fred's.
2) Added Cotter Pin for fairlead.

With Fox 25 BB, Graupner 10-4 prop, weight is exactly 40.0 oz.

Hits:
Nice instruction manual with clear pictures.
Best wing cutout of Arf Profile that I have seen.
Goes together pretty fast.
Looks cool, but just like Fred's!

Misses:
Leadouts aren't bushed in a metal bellcrank. It does have two loops of the leadout, but I'll have to examine that over time--which is easy to do using the hatch. However it doesn't look easy (or even possible) to remove the bellcrank.

Pushrod connection to bellcrank uses a RC feedthrough which screws down on the pushrod. I used my trusty blue locktite to flood the screw and feedthrough hold to keep things tight, but we will see.

Also no fairlead. I thought that was unusual, since the pushrod does flex when up line is pulled.

Pushrod connection to elevator uses clevis. I again pulled out the loctite to add some anti-vibration resistance to the clevis/pushrod threaded area, also added some to the locknut.

Also the supplied hinges were the CA type. Again I went with the flow here and used them.

"Unusual" crimp for outside part of leadout. All Sig kits and Sig Leadout products I have seen show a 3 pass of the leadout cable through the crimp tube. Here we have just a 2 pass. Well I will see.

No Sig 1/4 oz weights for weight box. Maybe not a big deal, but since the instruction book mentions 3 of these weights to start with, it would have been nice to have provided 3. Now I need to scrounge up some --probably from another plane!....

Stock clunk tank is rigged up to mount wide side out. This puts the pickup and/or uniflow vent pretty outboard. Here I cheated and mounted it wide side up, (narrow side out). The only problem with this is that this tank, a Kavan, has a ribbed structure on the tall sides, and this will interfere some with the smooth movement of my clunk, but it was my choice. I plumbed as a two tube uniflow (I fill the tank through the uniflow, by holding the tail vertically, with the air venting out the needle. I am just lazy when it comes to clunk tanks. Also a negative I think is that the tubing is brass. Maybe in Europe (where the Kavan is located I think), maybe FAI fuel leaves the brass alone. Anyway I went stock here too. I thought it was a little unusual that the manual doesn't mention uniflow--but it does say this isn't a trainer, so maybe that means you should know some things!

One comment is that the instruction book says to use an iron at ~220 deg to shrink the covering some more. That just sagged mine. I went to ~320 and now the covering is nice an taut.

I realize there seem to be a lot on misses here, and to some extent they are a little on the nit-picking side. What I think is telling is how all the Arf manufacturer's (Top Flite, Brodak, and Sig), have issues with the control systems. I think that of the 3, the Sig looks the best quality to me, but even so the Arf simply doesn't have a good (engineered also) a system as what you get with a Sig Slyray kit. Not too sure I understand why, except the kits are put in the box in China, and it must be a lot of effort to either ship the good stuff there to include, or to open the box when it hits the states to put in the good stuff.

Anyway, I am looking forward to getting this baby up in the air tomorrow. We will see how it compares to Fred's Force. Maybe we should learn to fly formation!

Steve Holt · « **Reply #16 on:** June 06, 2006, 12:19:39 PM »

Mine was built stock except for a carbon fiber tube over the pushrod for stiffness. A fairlead was a possible alternate, but the tube was easier for me.

I had planned to power the airplane with an FP25, but it was quite tail heavy with that engine, so I used a GMA mod OS25FSR. The airplane flew great with this engine but was very quick on the controls so I switched to a longer control horn. I used a Sullivan 1 1/8 steel horn and am happy with the results. Total weight was right at 38 oz., not a lot heavier than my Skyray even though the PF has 100 sq. in. more area.

The FSR was run with a 10X4 APC prop and was more than enough power when the needle setting was right, but it was difficult to get just the right setting.

I am now flying it with a Thunder Tiger 36 on a 10.5X4.5 prop and it is much more repeatable.

This is a really good flying airplane and the landings are amazing. It is virtually impossible to screw up a landing with this airplane.

There are a few loose areas on the covering on the fuselage, but other than that it has held up very well for over 100 flights.

This is the best of the ARF's that I have seen and I've had a Nobler, Flite Streak, and Oriental.
Steve

Alan Hahn · « **Reply #17 on:** June 10, 2006, 11:18:33 AM »

Just an update on the PF. I took the plane to the field, but when I started the Fox 25 BB, the vibration level was so high that I shut it down (~12k rpm on a Graupner 10-4 prop). I tried another prop (also Graupner 10-4) courtesy of Fred K., but that gave the same result. I decided that the PF front end and the Fox were just not meant for each other.

Took it home and decided to go for a Saito 40a. Turns out that its mounting lugs are within 1/16 of an inch of the Fox 25 (lengthwise), and spot on widthwise. And as a bonus the prop ends up also in the same place. So out came the dremel and I opened up the Saito holes a little. [editorial comment: I don't care if I spoil the resale price for some future motor collector--this engine is for my enjoyment!!)

I put a 3 blade Black Tornado 10-6 prop on. Yesterday I had a chance to start the engine at the field, and it was turning the prop at ~9.8krpm, with the PF front end happy. I may have to throttle back a hair to get the speed in the right place. Didn't have time to actually fly, the storm clouds were headed towards me.

Steve Scott · « **Reply #18 on:** June 27, 2006, 09:34:56 PM »

Primary Force ARF in Action at Sig Contest

I originally powered ours with an FP 20 w/BBTU mod. First flights in a moderate wind were disappointing. Model felt light on the lines to the extent no maneuvering was attempted. I sure couldn't see one but the wing must have had a slight warp which caused the outboard wing to fly high when upright. I didn't feel confident enough to pull it inverted to check. Lap times on 60' lines were 5.3 seconds.

Only modification to the stock configuration was substituting MonoKote hinges in place of the CA hinges.

After getting some suggestions on SSW I opted to re-engine it by dropping in a Brodak 40. No cutting was necessary but I did have to drill new holes. The B40 is a pretty lightweight engine. APC 10-4 prop and stock muffler and an all-up flying weight of 39.5 oz.

I used a heat gun to unwarp the wing then with time running out before heading down to the Sig meet I had my 14 year old fly it. The B40 produces much more useable power. It seemed fast watching it from the outside but the kid said he really liked it now - especially how it turned. He did wingovers, inside and outside loops and some inside squares. I had added another ½oz of tip weight in the built in box.

I entered him in the Sig P40 event as a junior as well as PAMPA Beginner. I didn't complete the modifications on my Fancherized Twister so was going to fly either a U-Key 40 (FP 25), a TF Flite Streak ARF (FP 20) or TF Tutor II (LA 46) depending on the wind conditions at Sig.

On the drive down to Sig my son was asking me the sequence for the beginner pattern. He also said he wasn't sure he wanted to compete in P40 but I urged him to go ahead since CD Mike Gretz said they usually have separate prizes for the juniors.

He also replumbed the stock Kavan tank to a uniflow setup. We did put the extra vent tubing through the fuselage.

First flight in P40 at Sig he successfully completes the entire beginner pattern - the first time he ever attempted the pattern in sequence and scores a 241.5! Positive comments from the other fliers that his corners look really crisp but the speed is pretty fast (he says he's comfortable with the speed). He passes on his 2nd flight and ends up as the top junior in P40.

His first flight in Beginner PA he got a little confused and started the wingover without completing sufficient laps after takeoff & level flight. Additionally he does the wingover going into the wind! Still pulls down a 207 without pattern points. Bob Arata, who is judging Beginner, advises him to fly 5 laps after takeoff. Next flight he nails a 259 to best all the open fliers in Beginner (including his old man). He scored a 35 point landing. Even I could get that score landing this ARF - it is that smooth!

There were at least 7 or 8 other PForces in action at Sig. Five were ARFs and 3 kit/scratch built. One of the ARFs was Gretz's electric powered version.

Most of the PForces utilized the LA 25 and at least one a Fox 35. It seemed to fly just fine with either. A few of the other PForce fliers were commenting that the PF was a very "honest" airplane. Certainly it is capable enough for a young flier to go out with zero practice and become an contender. With 27 entries at Sig, the P40 event is an incredibly popular event. Having a competitive airplane which saves you the 10 pt no flap bonus is a big, big advantage.

Mr. Pratt has come up with a winner - it certainly made my son a winner at Sig!

Mike Gretz's electric Primary Force ARF seen at the Sig meet:

Bill Little · « **Reply #19 on:** June 27, 2006, 10:20:17 PM »

HI Steve,

That's GREAT!! I love it when a son beats his old man.

Mine does it to me most of the time, now.

Of course it's the age thing, those young bucks are just in better shape. I can almost remember being 14.............

Sounds like the Primary Force is a winner, too.

Keep up the fun, and best wishes for you and your son! Congratulate him for us!

Bill <><

Steve Scott · « **Reply #20 on:** July 04, 2006, 12:33:51 PM »

Quote from: Alan Hahn on June 04, 2006, 06:39:37 PM

Here's my review of my Primary Force Arf.

No Sig 1/4 oz weights for weight box. Maybe not a big deal, but since the instruction book mentions 3 of these weights to start with, it would have been nice to have provided 3. Now I need to scrounge up some --probably from another plane!....

I was puzzled by the book's suggestion since ours came with what looks like a ½ oz weight (the rectangular Sig weight with the hole in the center) already installed in the box. I added another ½ oz plate and it seems pretty close.

Alan Hahn · « **Reply #21 on:** July 06, 2006, 09:05:31 PM »

You are right, I found that 1/2 oz piece when I opened up the weight box. So I added just one 1/4 oz weight. Unfortunately, the first flight vibrated the box back open agian, so I had to put some more in anyway. It isn't a really big deal, but I always get excited with a new plane and want to get it out. If you don't have the weights in the box, it isn't easy to come by them on short notice.

Author Topic: Primary Force (Read 4534 times)

Big country Joe

Alan Hahn

Alan Hahn

Alan Hahn