Author Topic: Shy Fox Revealed (Read 3222 times)

Balsa Butcher · « **on:** December 21, 2010, 06:25:18 PM »

A few weeks ago I was asking questions about Super Slow Rat Racing. Well, questions were answered and this is the result. Dave Hull's "Shy Fox" built from Model Aviation plans. Finish is monocote and Sig dope. Power an FP-25, changes from plans are ply outboard doubler rather than aluminum and fuselage lengthened 2" for weight and balance reasons. Fun project, now back to the serious business of making stunt planes.

john e. holliday · « **Reply #1 on:** December 21, 2010, 08:24:42 PM »

That looks great. I have the plans and plan on getting one built. Balanced right, I bet it would do most of the pattern.

BillLee · « **Reply #2 on:** December 22, 2010, 03:55:35 AM »

Nice looking model, Pete.

I note your comment about "fuselage lengthened 2" for weight and balance reasons".

Did you build it to actually race, or as a sport/stunt model?

Reason for asking: the CG of a sport/stunt model will be different from one for a racing model. It is very typical that a racing model will be balanced considerably further.

Regards,

Bill Lee

Balsa Butcher · « **Reply #3 on:** December 22, 2010, 08:42:29 AM »

Hi Bill, it will be used for racing. With a thin wing, 2" bellcrank and limited elevator movement it won't be doing the pattern (or hopefully any other "trick") any time soon. Weight though is an acceptable 27 ounces. Wish I could get my stunt planes to build that light.

Actually, I originally built it per plans with a 5" distance between the wing TE and horiz stab LE. A rough assembly revealed a severe nose heavy condition. I measured the moment of my Super-Fly which balances and flies well with a Fox 35. It has a 7" moment, shorter nose and no fuel shut-off. This led me to the decision to lenghten the fuselage to the same moments as the Fly.

The nose heaviness of my plane may have come from susbtituting a wire landing gear and 2 plywood doublers for the aluminum doubler/landing gear and single ply doubler that Dave used. Also, I used the smaller stab/elevator shown on the plans rather than the larger ones he used on the protoype. At an rate, my gamble seems to have worked as it balances as shown on plans. Only flight testing to show for sure if it was a good idea or not but I'm confident that it will fly well.

Gary_Marchand · « **Reply #4 on:** December 22, 2010, 06:47:20 PM »

Pete, as your unofficial pit man, what is super slow rat racing? Is it what we have been doing with the Fox 35? Also, where did you say I can buy a 2 Oz racing tank. After building 3 anchor sieves, I tossed my soldering iron in the Rio Grande and decided I was not meant to be a tank builder, or at least the fuel tank kind. Now a M-1 I could handle. Anyway, can you give me an URL? Or anybody else that knows a source. Nice Shy Fox by the way.

BillLee · « **Reply #5 on:** December 23, 2010, 03:01:41 AM »

Hi, Gary;

I'll throw in an answer and perhaps Pete will as well.

Best place to go look for the unofficial racing event rules is the NCLRA website.

http://www.NCLRA.org

There you will find a link "Racing Rules" and on that page another link to "Super Slow Rat". You'll also need to look at the "NCLRA Fox Racing" link since the SSR rules are essentially a Fox Race derivative.

As to tanks: I hope Pete can give you an answer!

Regards,

Bill Lee

Dave Hull · « **Reply #6 on:** December 23, 2010, 06:29:27 PM »

Pete,
Nice looking racer! I hope you have a lot of fun with it.

The big wheel should be great for grass, or pavement that is on the rough side. The wire gear may be more forgiving for pilot technique on hard landings. Be sure to retain the "magic location" of the wheel contact point 15 degrees ahead of the measured CG. This allows the pilot his best shot at landing and getting into the pits cleanly without bouncing it around in the pitman's face. (I always got the vague idea that they don't like that--at least mine always chewed me out for doing that....) On the other hand, if you are racing on grass, it may have to go farther forward. I don't have any advice on that because we have no grass fields out here. Well, we have one gopher patch, but no one can land anything on that.

I suspect that the initial noseheavy condition results from a fuse blank that uses "stunt wood" and perhaps no glass reinforcement? The other changes that you listed would likely have made the nose lighter than the prototype. For example, the full aluminum doubler/gear leg has got to be heavier than the plywood replacement. The two prototypes used firm balsa (I probably have the measured weights somewhere if that would help) that was probably around 10 lb/ft^3 stock. The fuselage was fiberglassed with one layer of .058 oz/yd^2 that was pressed, so very little epoxy. All covered with one coat of clear epoxy paint. Similar treatment for the stabilizer. So not typical sport or stunt construction, but fairly typical of a racer. Yet the overall weights are comparable. Hmmm. If you used lighter wood and no glass, be sure your pitman knows to nose-catch and not wing catch.... And let us know how your stretch fuse, small tail version flies. My second prototype also had the small tail, and does not suffer from any reduction in groove or maneuverability.

A comment on fuel tanks: you will probably not need/want a full 2 oz tank if you are racing with an OS FP. It means your pitman will have to short tank, which takes extra skill and a bit of luck. (A "count of three" squeeze on the filler bottle on the first and second tanks, and topped off for the last.) We raced my ShyFox earlier this month with a new pitman, and we got in three practice flights before the race. He really lucked out--we had one extra lap at the end of the race when the engine died! Depending on your field elevation and the humidity level, you might get 60-70 laps out of a full 2 oz.

I like the logo on the rudder. I might add one to mine to remind me which way the plane should be going!

Good luck, and please let us know how yours flies!!!

Dave "McSlow" Hull

Balsa Butcher · « **Reply #7 on:** December 23, 2010, 07:10:22 PM »

Dave: Thanks for the kind words and encouragment. A little more about the airplane: This is the second fuselage I cut, first one was "stunt" wood...could tell right away it was going to be too soft. Found some medium that felt about right and that is what this one has. The fuselage and vertical fin (basswood as per plans) are covered w/.5 ounce Sig fiberglass and 2 coats of Z-poxy (love that stuff) then sanded smooth. Horiz stab is not fiberglassed but is firm balsa w/ bass wood and CF spars, SGM grade silkspan and dope finish. Seems pretty strong but probably should have fiberglassed it as well.

The large wheel was just one I had lying around but it looks like it will work well as our usual flying surface is pretty rough. I'll confirm the "magic location", it should be close. As far as the nose heavy condition, still a mystery but not an issue anymore. Actually with "Super Fly" moments and landing gear, maybe I should call this a "Super-Fox" or "Shy-Fly". The wing LE and bass wood spars are CF reinforced per plans. Nice idea, I will use it on carrier planes that can also take a beating and have thin wings. Tank on this one is 1.5 ounces, got it from one of the Texas racers a few years ago. The 2 ounce tank that Gary is inquiring about is on my Super Fly with the Fox 35, not on this model.

Gary: SSR is what we have been doing with the Fox 35 racers except with modern, plain bearing .25 engines. The 2 ounce tank I have on the Fly is Northwest sport race tank made by Todd Ryan. He advertises in "Flying Lines", the on line newsletter of the NW CL folks. Check it out at "Flying lines (dot) org".

Jim Snelson · « **Reply #8 on:** December 23, 2010, 10:13:55 PM »

Looks good Pete. I can't wait to see it out at the field so we can see it fly. Maybe at our next meeting on the 8th?

Jim Snelson
www.clcentral.com

Balsa Butcher · « **Reply #9 on:** December 23, 2010, 10:37:53 PM »

Thanks Jim, I plan to be there. Let's hope for flyable weather. Merry Christmas to you, Emily, and the family.

Jim Snelson · « **Reply #10 on:** December 23, 2010, 10:58:22 PM »

Merry Christmas and Happy New Year to you and Lois also.

Hopefully the weather will be better than it is right now by then and we can get in some flying and see how much we disturb the neighbors.

If you get into to town before then let me know. I have a couple of projects I think you will be interested in and want you to take a look at them and give me your opinion on them.

See you later.

Jim Snelson
www.clcentral.com

Balsa Butcher · « **Reply #11 on:** December 24, 2010, 10:34:15 AM »

Can't wait! and Gary, per Shy Fox article, Brodak BH-582 or BH-566 tanks will also work. If nothing else, we can mount my 2 ounce tank on your plane and get some flights in.

Jim Snelson · « **Reply #12 on:** December 24, 2010, 01:34:36 PM »

I have a few of the 1 1/4 oz and 1 1/2 oz tanks at the store if you want to try them Gary. It is what Lance and I are using on our racer until we get something else.

Jim Snelson
www.clcentral.com

dale gleason · « **Reply #13 on:** December 25, 2010, 10:39:22 AM »

Wonderful looking ship! From my limited perspective and experience, it cannot be nose heavy enough. I mean it! Especailly in places such as ABQ, ICT, DFW where the wind is always blowin' hard. Without a shutoff it will just about always quit and be in need of some serious whipping to get safely into the pits. Nose heavy is good, they follow their nose. Abut the twentieth time your pit man runs/walks/crawls to the far side of the circle where you land, he will be tellin' you to add something like a horshoe on the nose so you can sling that rascal to him. Or he might suggest tradin' places with you and get even....

See you in ABQ,
dale g

don Burke · « **Reply #14 on:** December 25, 2010, 11:25:23 AM »

What I do to make sure I get in the two stops required. First the tank is only 1-1/4 oz for my B25. It will get over 50 laps on my normal prop. Rather than build a new tank I warm the engine up during the 2 min prep. Run about 30 sec of the 2 minutes, then DONT refuel for the initial start. IF the fuel pickup is in the bottom of the tank and the tank outside edge is outboard of the NVA, it should get off the ground with stuttering. I find that in the heat of action during a pit stop, if I try to short tank it, it doesn't work out and I end up filling the darn thing when i don't want to. I also found prop pitch will affect the range, if you're getting too many laps lower the pitch.

john e. holliday · « **Reply #15 on:** December 26, 2010, 02:00:16 PM »

I put tanks on big enough to get enough laps, that if something happens to cause a short session at start of race I can refill an finish the race. I use shut offs and if not allowed I leave it in the car. Nothing like having to pit with about 5 laps to go and no shut off. With the exception of mouse I think all racing planes should have shut offs.

Gary_Marchand · « **Reply #16 on:** December 26, 2010, 09:07:51 PM »

Thanks Pete and Jim. Will Check the tanks you have when I get back, Jim. Got Todd's contact info off the news letter and will wait until I get a few flights in before deciding on whether I need a two oz tank. Probably won't be back for the meeting, but will try it first opportunity. We may be getting into the predicament where we have more racers than we have pitmen/flyers. Since I walk like a drunken sailor anyway, I am to dangerous to fly three up. As your pitman, at least in Albuquerque, I second what Dale said earlier about whipping that hog. Getting to damn old to go sprinting around the circle.

Gary

P.S. Bill Lee, you need to come to Albuquerque next August and show us local yokels how it is done.

BillLee · « **Reply #17 on:** December 26, 2010, 09:12:44 PM »

Gary, Tucson is pretty close to Albuquerque. Why don't y'all make THAT "local" contest?

Albuquerque is sure a lot of fun. Will have to see how the finances and time work out this summer.

Bill

Balsa Butcher · « **Reply #18 on:** December 26, 2010, 10:04:25 PM »

Good to hear from you Gary. Actually, one of the main reasons I built the "Fox" was to get us an engine that starts easier than a hot Fox .35. As far as the pit-stops go, guess we had better get a few practice sessions in before the contest unlike the last 2 years were we just "went for it".

Hope you all can make the ABQ contest in August - last year was a blast.

Dave Hull · « **Reply #19 on:** January 05, 2011, 02:23:42 PM »

Dale,
As far as CG location, trim, and overall weight are concerned, the MA plans show the as-built configuration of the first prototype ShyFox. No secrets held back. It can be built lighter, and it can use less tip weight but the configuration shown is set up to race very well in the wind. It has plenty of penetration and is easy to whip. I raced at one location where my 25 lb tool box blew over in the wind....

No reason at all to make your pit man leave his hand selected, choice, piece of real estate. (Pitmen are very territorial. For those that may not believe this, try landing your plane in someone else's pit and see what happens!) I found this plane grooves real well with the trim as shown and can be raced "eyes off." All that tip weight makes it tolerant in gusty conditions on takeoff, and makes it easier on the pilot knowing it is not likely to torque roll unless severely provoked. In fact, the real downside of all this stability is that the plane does not "shake down" easily unless the pilot is really aggressive or uses a larger handle than I do. I should say that I fly using a 2" handle spacing with no overhang.

I'm sure you could balance the plane even further forward since the control surfaces are large/powerful but I suspect most pilots won't need to.

Looking forward to hearing results of flight testing!

Dave "McSlow" Hull
So Cal Air Racers

PS--Our club Pres thought that Peter was going to visit us last weekend at Apollo field. Sorry we missed you!

Balsa Butcher · « **Reply #20 on:** January 05, 2011, 04:50:14 PM »

Hi Dave, thanks for the tips. Test flight will be Saturday in Albuquerque. Sorry 'bout the no show at the Basin this Saturday. Left in a blizzard which followed me about 260 miles west bound on I-40. Had to leave the airplane hauler at home and take the snow car. No room for planes then got caught up in family stuff. Hopefully next time

.

Dave Hull · « **Reply #21 on:** January 06, 2011, 02:39:15 PM »

Peter,
Next time. At least you managed the trip without the toy hauler. (I would have brought out the original if you wanted to try it....)

Dave

Balsa Butcher · « **Reply #22 on:** January 09, 2011, 12:06:31 PM »

Two tests flights revealed a really sweet flying and potentially very competative airplane, a pilot who needs a lot of practice, and an engine that starts easily but still needs to be dialed in. Overall - great success

john e. holliday · « **Reply #23 on:** January 09, 2011, 02:25:15 PM »

Looks like I am going to have to get started. Glad it is working for you.

Balsa Butcher · « **Reply #24 on:** January 09, 2011, 02:38:38 PM »

Go for it Doc, you won't be disappointed. As far as the controversial rear fuselage extension, it worked out OK, but if I had to do it again, I'd only go 1" instead of 2". If you use a B-25 which I hear is the current hot set-up, the stock length will probably work out fine as I believe they are lighter than the FP-25 that I am using.

Bill Heher · « **Reply #25 on:** January 10, 2011, 11:05:34 PM »

Here are a few pics from Saturdays practice session- sorry they are blurry- it seems the lens on my cheapo digicam got some exhaust residue on it. Real nice day and some good practice racing.

Bill Heher · « **Reply #26 on:** January 10, 2011, 11:18:39 PM »

Couple more - Russ an Ross from Los Alamos w/ Dick Perry doing rules review and tech inspection, Dick with his ST .35 powered Slow Rat, Burt test flying the now deceased Yak-9 .. sorry Burt!