Author Topic: Rat Race (Read 3729 times)

Steven Davenport · « **on:** October 09, 2009, 06:24:12 PM »

Hello everyone,

I am building a Carl Goldberg Skat rat after 37 years away from the circle. This is the plane I used when I was a kid. I used a K&B RR .40 reworked by Vic Garner out of Livermore, ca who was the one that taught me about building and flying. I am going to build it just like I did when I was a kid. Same engine, Fuel cut off, Pressurized fuel tank, and plug connections on the wing for hot glove. So, this plane will really be for my own personal gratification remembering the old days and Give me practice for when I build one that I can use in a contest.

What I need is suggestions on what to build for a contest. maybe some pictures of planes so I can see what is new and how to do it. I live in Arlington, WA and there is no one out here that flies Rat Race. I do have a great friend in AZ Bob Christ who I correspond with and he is helping me immensely with the tools I need to get going again. I have read the AMA rules and know the specs but now I need the expertise.

Thank you for helping.

Steven Davenport

BillLee · « **Reply #1 on:** October 09, 2009, 07:35:25 PM »

Hi, Steve;

Rat Race as it exists in the AMA rules is now a .15 event, no longer using the 40's that you are familiar with. The event got so fast and the planes so heavy that they were all but un-flyable by mere mortals.

If you want an event that is VERY similar to what you described, take a look at Texas Quickie Rat. This is an event that is an NCLRA (National Control Line Racing Association) event, and the rules for it can be found on the NCLRA website at http://www.NCLRA.org/ This is the most popular racing event in the U.S. at the current time.

Regards,

Bill Lee

Steven Davenport · « **Reply #2 on:** October 09, 2009, 07:53:04 PM »

Hi Bill,

Thank you for the information. So Looks like I can can fly Texas Quickie Rat then. I do believe I can use a front rotor K&B .40 for this event but with a lot of modifications to slow it down according to the rules. I will need help on the current specs for building of the plane. What is everyone using for this event, etc. What about B team racing? Isn't that the old timers event? Yes I remember how fast we used to go. I am still dizzy. HEHE

Steven Davenport

BillLee · « **Reply #3 on:** October 10, 2009, 11:35:33 AM »

Hi, Stephen;

Yes, the Scat Rat is suitable for TQR although far too large by today's standards. And a K&B front Rotor 40 is the de facto engine to use. I don't think you'll have to do anything to make it SLOWER since there is no speed limit on the event. The key is that the engine must start out as a production engine, you can remove metal but not add (some exceptions), and the venturi and needle assembly restrictions are absolute. Beyond that, a profile model with external controls is about all it takes.

(Obviously I have greatly paraphrased the actual rules, so see them for the details.)

Regards,

Bill Lee

Steven Davenport · « **Reply #4 on:** October 10, 2009, 11:48:01 AM »

Bill,

I built the Skat Rat with internal controls. Why the rule for external controls? I also will be getting plans to build a barracuda witch is what I will probably use in a contest. I will be getting a K&B FR 40 that is already set up from a friend. The motor was reworked by Vic Garner so should be perfect and ready to go.

What other planes are used in this event? I have seen many pictures of current planes but not sure what they are or were to get kits or plans. They all look similar to the Skat Rat in some ways and I am sure most of them are scratch built. So I guess I could just do my own design following rule guide lines. It would be great if the Rat Racers on this forum would chime in and post a few pictures and links to get what I need.

Thank you

Steven Davenport

BillLee · « **Reply #5 on:** October 10, 2009, 10:44:46 PM »

The Barracuda is an excellent TQR and will be very competitive with a Vic K&B.

The rules require external controls because ... they require external controls. Just like a lot of rules, it is a line drawn in the sand.

Actually, external controls make the model easier to build. External controls add one small additional bit of drag to keep performance down. Don't forget that the lines have to be connected to leadouts that extend beyond the wingtip, and leadout guides at the wingtip cannot be longer than 1/2"

Bill

Steven Davenport · « **Reply #6 on:** October 11, 2009, 05:44:57 PM »

Bill,

Thank you for the information. Does anyone else have any suggestions that will help me along?

Thank you

Steven

Steven Davenport · « **Reply #7 on:** October 17, 2009, 01:06:21 PM »

What should the fuel capacity be with this plane? I need to get at least 36 laps on a tank. I am using a K&B FR .40 Are there newer designs available?

Thank you

Steven

Paul Smith · « **Reply #8 on:** October 17, 2009, 02:05:24 PM »

Bill,

The rules list a lot of specifications for the engine.
How about sparing us the reseach project and listing the engines that comply with the rules?

BillLee · « **Reply #9 on:** October 17, 2009, 06:36:33 PM »

Quote from: Paul Smith on October 17, 2009, 02:05:24 PM

Bill,

The rules list a lot of specifications for the engine.
How about sparing us the reseach project and listing the engines that comply with the rules?

Code: [Select]

ENGINE SPECIFICATIONS:

   1. Maximum total displacement shall be 0.4028 cubic inches (6.6cc). Engines must be production units assembled from factory available production parts.
      Engines and parts must have been produced in quantities greater than 500 and all must be or have been available through normal retail outlets in the USA.
      Parts substitution shall be limited to catalog listed parts produced in quantities greater that 500 units for the engine being altered and available commercially
       to anyone from the manufacturer of the engine. Engines may only be modified by removing parts or material from parts except as noted in the following 
       paragraphs. No material or part may be added except as noted in the following paragraphs under this section.
   2. The "engine" is defined as the complete unit, ready to run, needing only prop, fuel and starting voltage except that the glow plug, venturi and/or restrictor,
       spraybar and needle valve, gaskets, bolts, drive washer, front washer, prop nut, shims, piston ring(s)(if used) and ball bearings (if used) need not be
       considered part of the production unit. These parts are not subject to the rules regarding quantity or source. In addition, chrome plating of a production 
       cylinder is allowed.
   3. The glow plug must have a thread dimension of 1/4-32.
   4. The engine must be of the front intake configuration. All air for the combustion process must come through the crankshaft. Altering nominal sub-port
        induction, timed holes in the case and sleeve or other techniques to circumvent the requirement that all air come through the specified venturi opening
       are not allowed.
   5. Only single by-pass port engines are allowed The engine as purchased and as used shall be of the single by-pass configuration. No schneurle or PDP 
       porting is allowed.
   6. No ABC or AAC piston/sleeve configurations are allowed.
   7. No variable area carburetors shall be allowed. Each engine shall be equipped with a venturi and spraybar meeting the following restrictions:
         1. The venturi shall have an inside circular bore of not more than .292". The venturi will maintain this diameter for at least 0.155" at the throat of the 
              venturi where the spraybar will be located at the midpoint of the area.
         2. The spraybar assembly will be located precisely through the centerline of the venturi bore and shall have a constant circular cross section of 
             diameter not less than 0.153" for the portion in the throat of the venturi. 
   8. No tuned pipes, mufflers or exhaust extensions are allowed.
   9. The complete engine/venturi/spraybar system shall weigh less than 10.5 ounces.

Steven Davenport · « **Reply #10 on:** October 17, 2009, 07:20:39 PM »

Bill,

Thank you for posting that. I have a copy and have read it. I have a K&B FR 40 that is already set up to specifications. My question is I do not know how big my fuel tank should be. 3oz, 4oz? to get 36 laps.

Steven

BillLee · « **Reply #11 on:** October 18, 2009, 03:06:10 AM »

Hi, Steven;

That last post was not for you but rather for another.

As to tank size: easy answer.

I don't know.

I think a 3oz tank will suffice, but unless changing tanks after the model is built and flown is easy, I would probably just go with the 4oz. That WILL be big enough, probably for far more than 36 laps.

The downside of a too-large tank is carrying the extra weight of the fuel that is never used.

The upside is that if you need to stop early in a tank to make a quick needle adjustment, you will haver enough fuel to go the rest of the race without another pitstop.

Bill

Paul Smith · « **Reply #12 on:** October 18, 2009, 08:26:55 AM »

Thank you for the posting the engine rules. That is exactly the same set of rules that I found on your site.

So, my question remains;
In addition to the K&B FR 40, is there any other engine that meets these rules?

Steven Davenport · « **Reply #13 on:** October 18, 2009, 09:40:21 AM »

Bill,

I was thinking about the weight as well. Like you say, I can always change tanks if needed.

Thank you

Steven

BillLee · « **Reply #14 on:** October 18, 2009, 09:58:13 AM »

Quote from: Paul Smith on October 18, 2009, 08:26:55 AM

Thank you for the posting the engine rules. That is exactly the same set of rules that I found on your site.

So, my question remains;
In addition to the K&B FR 40, is there any other engine that meets these rules?

Paul, I know you are trying to create a controversy here, and I really am not desirous of taking the bait. You know the answer to your own question.

Scott Jenkins · « **Reply #15 on:** October 19, 2009, 07:21:17 AM »

Hi All,
Your friendly moderator here, please no games or controversy here keep it nice.
Paul do your homework if you think there is another engine that will comply with
the rules. Many have tried to use other engines but few if any will outrun a
properly setup K&B. Been there looked at all that they are all either too heavy or
have the wrong piston cylinder configuration.
Bill you did your part by listing the rules nuff said.

Scott Jenkins
AMA 43122
The moderator of this here forum !

BillLee · « **Reply #16 on:** October 19, 2009, 10:54:46 AM »

Thanks, Scott.

Bill

Les Akre · « **Reply #17 on:** October 26, 2009, 08:18:47 PM »

To answer Paul's question...there are several engines that can, or will meet the rules. Besides the K&B, there are the, S.T. G21-40 F.I., the O.S. Max .40, and the H.B. .40 (non perry port version) although this last one may need metal removed to make the weight limit (which is allowed in the rules). There may be others, but these are a few that come to mind.

You shouldn't need more than a 2.5oz. tank. Mine is around 3oz. and gives 92 laps! Way too much, but the tank works so I haven't changed it.

Les

Steven Davenport · « **Reply #18 on:** October 27, 2009, 12:22:41 AM »

Hi Les,

Thank you for the information. I will use A k&B .40 FR. Seems to be the engine of choice. I used K&B RR .40 on a skat rat back when I was a kid. That darn thing was fast. I look back at that and it is hard to believe we didn't trip over each other with 4 in the circle. Well, sometimes we did but Lots of fun.

I am glad you brought up the fuel tank. I built a 4oz. Now I see way to big so will build a smaller size.

Thank you

Steven

Les Akre · « **Reply #19 on:** October 27, 2009, 10:54:50 PM »

Hi Steve

If you need some correctly sized venturi's for the K&B 40 to use in the TQR event, contact James Lee. He is in the vendors section of this forum under Lee machine Shop. He makes a venturi sized as close to the max limit of .292" as possible. I think they cost around 12 or 14 dollars.

Les

Steven Davenport · « **Reply #20 on:** October 27, 2009, 10:59:13 PM »

Hi Les,

I appreciate the information. The .40 I have has already been reworked by Vic Garner out of Livermore, Ca. He was my teacher when I was a kid. I will keep James Lee's info for future reference.

Thank you

Steven

john e. holliday · « **Reply #21 on:** October 28, 2009, 05:02:02 PM »

Steve, remember back in the day of the Skat Rat we ran full crankcase pressure engines. I also remember the first time I got one to go 115+ consistently. Back then didn't have hot glove or fast fill as such. Remember the old Perfect squeeze bulbs. Used to carry carry two of them which got replaced each year. I guess from what I have read here I can put my old Tigre on with a new legal venturi. I still don't think venturi size is the answer. Anyway have fun, DOC Holliday

Steven Davenport · « **Reply #22 on:** October 28, 2009, 05:50:14 PM »

Hi DOC,

Yes full crankcase pressure engines. I was thinking we were going 120/130 mph or so on 60 foot lines back then. I had the hot glove set up, quick fill, and cutoff valve all set up on my plane. Yes I remember those fuel bulbs and they didn't last very long. I am going to use a K&B FR .40 on my plane and will test different configurations of props and venturis that are to specs to get the best performance. Those were the good old days though. To bad they slowed the speeds down. Safety first.. Good talking to you.

Steven

W.D. Roland · « **Reply #23 on:** November 10, 2009, 08:06:54 PM »

Steven I see the bug has bitten you as hard as it has bitten me!
Hi Bill!

Digging in old engines and found an old K&B fr R/C engine with broken case at venturi area. Dug some more and found 2 good front housings!
So the next step was to go by Darrell's house and beat him out of a quickie type I gave him years ago after Ron moved of and left me all his C/L racing stuff( pan rats and Goodyears also)

Now I have all needed to get a quickie up except the pilot.
Working on youngest son(24) to be pilot of this and a F-40 pan rat.

Do need to check Bills rules on tank pressure and other things.
Not an immediate project yet as mainly sorting stunters and the pilot(me) currently--slowly getting it!

Steven.....they had to slow rat down.
When I stopped in 75 we had our pan rat K&B 6.5 moving at over 160mph and did a 161+mph F-40 flight with a rich needle. Only 2 people in the circle for racing and even that was almost impossible.
The pilots had to help each other to maintain.
Some one told me fast rat was still flown in 82 but if you ask me it should have ended with the release of the 6.5.
It really was getting hairy and to the point where even as a brave kid started questioning the sanity of pitting them any more.
I understand that the current F-40 record of 174(?)mph with same 6.5 on 60ft lines is a difficult thing to do.

It was fun while it lasted is not in question!!

Hope to see everyone next year at contest.
Looking forward to meeting and re meeting all.

David