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General control line discussion => Open Forum => Topic started by: Michael Massey on August 08, 2011, 03:51:16 PM

Title: Shark 45 and a K&B 61
Post by: Michael Massey on August 08, 2011, 03:51:16 PM: I just ordered contest grade balsa wood to build a Shark 45. I have an old kit my dad had but plan on using the parts for templates. In any event, I was thinking about putting a K&B 61 in it, primarily because that is what I have. My first concern was the weight of the K&B 61 but the Shark plans call for a K&B 45. I don't know what the 45 weighed but a new K&B 40 weighs just 3/4 oz less than the 61. Albiet the weights listed on MECOA are not clear which includes muffler weight, a light weight modern muffler from Randy Smith would keep the "apparent" weight differential between the two motors close...I think.

Anyone have any experience with the weight difference of the older K&B 45 and newer K&B 61? What about balancing experiences with the Shark 45 and the weight of whatever engine you used.

Tx. for any input.
Title: Re: Shark 45 and a K&B 61
Post by: Randy Cuberly on August 08, 2011, 04:35:58 PM: The K&B 61 weighs approximately 12 oz without muffler. The old K&B 45 I believe was less than 10 oz.

Randy C.
Title: Re: Shark 45 and a K&B 61
Post by: Robert Redmon on August 08, 2011, 04:50:28 PM: I have both here in the shop. On my aging postal scale, the .45 weighs just over 11 oz. and the .61 weighs just over 14 oz. This is with prop nut and washer but no muffler.

Bob Redmon
AMA 58073
Title: Re: Shark 45 and a K&B 61
Post by: Dan McEntee on August 09, 2011, 01:34:31 AM: I built my two Shark 45's by copying the Jetco Kit and there are a few things to consider. First, I made my fuselage sides one piece by making them 3/8" wider that the kit pieces. That will help you build a straighter model rather than trying to align the front and rear halves on the wing. Next is the engine. Find out as close as you can what your fuel requirements will be, and measure the nose to be certain you can get a large enough tank in there. I moved the rear bulkhead all the way back to the wing leading edge so I could get a 6 ounce tank in mine. I used the late model ST.51 in mine, and they weight 11 ounces, I think, so if the K&B .61 is 14 ounces, be prepared to add tail weight if necessary for balance. Both of mine balanced out pretty well without any extra ballast needed. Landing gear length will need to be considered if you are going to use 12" props, so I made my landing gear removable so I could change the length if need be. And this also help when packing the model for a long cross country trip to VSC! Good luck with yours, I think you'll like it.
Type at you later,
Dan McEntee
Title: Re: Shark 45 and a K&B 61
Post by: EddyR on August 09, 2011, 07:29:57 AM: Michael
Building a model around a motor just because you have it many times is not a best idea. The K&B61 is a heavy and very wide motor. I have both the old style K&B 45 and the K&B 61. I have had Sharks with the old K&B45's and I felt they were under powered. I have seen them with the ST51 and 60's in them. The ST/51 was the best of the ones I have seen. I have put K&B 61's in Paternmaster's that are a lot bigger and much heaver than the Shark and the motor flew them easily. Anything can be made to work but I would not build that combination. I saw Lou fly his enlarger Shark at Tiften Ga about 10 years ago with a ST/46 in it and it flew very well.
Ed
Just went and weighted several motors
K&B .61=13.2 oz
K&B .45Green Head =8.8 oz
ST/46=8.4 oz
ST.59-60=12.4
ST/.51?? I think 11 oz. Maybe some one can add this in as mine are down for rebuilding.
Ed
Title: Re: Shark 45 and a K&B 61
Post by: Michael Massey on August 10, 2011, 12:06:51 AM: Thanks to all for the great input and information. I got the balsa today and it seems very light and looks good. But all goes on the bench for now as I pack tomorrow for a 5 day motorcycle trip from Oregon to Zion National park and Bryce Canyon park. Will look at getting to cutting parts when I get back.

Thanks again,

Mike
Title: Re: Shark 45 and a K&B 61
Post by: Steve Helmick on August 10, 2011, 03:53:02 PM: Quote from: Michael Massey on August 10, 2011, 12:06:51 AM
Thanks to all for the great input and information. I got the balsa today and it seems very light and looks good. But all goes on the bench for now as I pack tomorrow for a 5 day motorcycle trip from Oregon to Zion National park and Bryce Canyon park. Will look at getting to cutting parts when I get back.

Thanks again,

Mike

Sounds like a great mo'bike trip. Keep the A/C cranked up! y1 Steve
Title: Re: Shark 45 and a K&B 61
Post by: EddyR on August 12, 2011, 09:19:16 PM: Bryce is one of my favorite places. It is one of the darkest places in the US at night. Some times they have large reflector scopes set up at night at the parking lot across from the main lodge. I will be in Moab and right near Bryce in three weeks.
Ed
Title: Re: Shark 45 and a K&B 61
Post by: Howard Rush on August 12, 2011, 09:51:14 PM: Ask Bruce Hunt. He has a good Shark with a big engine.

Here I am at Bryce Canyon with a local. This was on a fine trip between the Nats and a Los Angeles contest.
Title: Re: Shark 45 and a K&B 61
Post by: EddyR on August 13, 2011, 12:22:18 PM: Howard Don't let your cats y1 see that picture,they will tear it apart. LL~
Ed