Royal Cessna 310Q weight?  
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Royal Cessna 310Q weight? - 6/28/2006 10:40:07 PM   
yl5295


 

Posts: 462
Joined: 7/29/2003
From: Raleigh, NC
Status: offline 		All,


What should the weight be on my (scratch built) Royal Cessna 310Q? I was planning on glassing and painting it but I am concerned that it is coming in heavy (I cut foam wing cores rather than a built up wing. All of the ply I used though is lite ply rather than aircraft ply. Also I used 1/16" sheeting on wing and tail rather than 3/32" since I was planning on glassing it. B&D retracts with the pair of OS40 FSRs. Flaps added also.


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RE: Royal Cessna 310Q weight? - 6/28/2006 10:48:29 PM   
William Robison



Posts: 20269
Joined: 11/10/2002
From: Mary Esther, Florida, FL, USA
Status: offline 		Bill:

With the information given all one can do is guess. The B&D retracts have an upper weight limit of fifteen pounds or so, B&D doesn't specify. I've used them for a long time, that's just my estimate.

The OS 40 FSR engines should do well at twelve pounds or so, but the plane wont be a rocket. You've heard theterm "Scale flight?" If you can keep it down to nine pounds the performance should be very nice.

Measure the wing area. wing loading in the area of 20 ounces/sq foot should be OK.

Bill.


_____________________________

Real Airplanes have Two Engines
AMA 25139 - More than 40 years.

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RE: Royal Cessna 310Q weight? - 6/28/2006 10:57:08 PM   
yl5295


 

Posts: 462
Joined: 7/29/2003
From: Raleigh, NC
Status: offline 		Wing area is 725 sq in. Airframe with retracts only is at 4.5 lbs now - what do you think? Still need to add engines, radio, finish, air tank and valves and pushrods for tail and nose gear steering. (and a TwinSync of course - this is the reason I started the whole thing).

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RE: Royal Cessna 310Q weight? - 6/29/2006 2:50:35 AM   
William Robison



Posts: 20269
Joined: 11/10/2002
From: Mary Esther, Florida, FL, USA
Status: offline 		Bill:

The weight of 4½ pounds is getting you a little close with 725" wing area.

If you can hold the engines and the radio gear to three pounds additional, the 7½ pounds will give you 23.8 oz/ft wing loading. Not too bad. The engines will handle it, but you wont have a sprightly aerobat. And it will fly pretty fast.

Then again, a Cessna 310 IS a fast airplane.

Bill.


_____________________________

Real Airplanes have Two Engines
AMA 25139 - More than 40 years.

(in reply to yl5295)
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RE: Royal Cessna 310Q weight? - 6/29/2006 3:05:42 AM   
yl5295


 

Posts: 462
Joined: 7/29/2003
From: Raleigh, NC
Status: offline 		So here are my thoughts....

Radio 1lb (7 servos at (5) x 1.5oz + (2) x .75oz + 4os rx pack + Rx and sync)
engines 2x 1lb each (I can't find a manual online for the 40 FSR but the 46 FX is 13.6oz so I think I am safe at 16oz ea inc. muffler)

That puts me at 7.5 lbs which means I can put about a pound of epoxy, primer, glass, paint and clear coat on it. Does that sound about right?

Which brings me to the question of how much does glass weigh finished?

The only reference point I have was in the 70s a pattern plane would float too much if it was less than 8lbs. Cover it in glass and get it over 8lbs and it would stay in the "grove" and you could spot land it. Funny,but I pulled out a vintage 1976 pattern plane and flew it recently and the landing speed was twice that of any other plane at the field. You used to paint and glass pattern planes to look good and not float. Scale twins are a different dynamic. I don't want a "lead sled" that can't get enough airspeed to be stable (like my first "true scale" P-38 turned out to be).

Yl5295

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RE: Royal Cessna 310Q weight? - 6/29/2006 3:48:15 AM   
William Robison



Posts: 20269
Joined: 11/10/2002
From: Mary Esther, Florida, FL, USA
Status: offline 		Bill:

Done carefully, a glass surface using 0.75 ounce (or lighter if you can find it) is only marginally heavier than using a film covering. If you are not intending the glass to be reinforcement in addition to giving a nice finish you can stick the glass down with water based polyurethane paint and save more weight. Easier too, and no nasty clean-up or picking the brush up and having the mixing cup come along when you try to stretch the pot life of the epoxy. Also less expensive.

If you’re looking at the glass for strength, stay with the epoxy.

Bill.


_____________________________

Real Airplanes have Two Engines
AMA 25139 - More than 40 years.

(in reply to yl5295)
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RE: Royal Cessna 310Q weight? - 6/29/2006 12:50:51 PM   
yl5295


 

Posts: 462
Joined: 7/29/2003
From: Raleigh, NC
Status: offline 		I have 10M of .75oz glass and was planning on using polyester resin (since I had a gallon can laying arround). Sounds like I am ok and should shoot to stay under 8.5lbs. I will weigh it again after completely rigged before putting any finish on it. Then disassemble and weigh it after glass and a couple of primer coats and sanding.

However 20oz/sq ft is only 6.3lbs. What is my upper limit on wing loading? I don't know if their wing area took into account the tip tanks and I am sure with this big fuse the fuse acts somewhat like a flying surface.

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RE: Royal Cessna 310Q weight? - 7/1/2006 2:26:43 AM   
Walter D


 

Posts: 667
Joined: 10/18/2002
From: Sun City, CA, USA
Status: offline 		Royal Cessna 310 Q, reminds me of lots of fun!
I built mine a very long time ago, had it powered first with two OS .35's and it flew great of pavement, then when I changed flying fields, grass runway this time I needed bigger engines due to the drag on the small wheels, I then powered it with two Fox .45's BB, and these engines pulled it with authority, flew at less than half throttle and it was fast, mine had Robart retracts, interior seats, etc, flaps, finished with fiberglass cloth, primed and then painted with automotive acrylic enamel paint, then it was clearcoated, had panel lines, rivets, etc., it was very sensitive to trim changes when flaps were deployed, elevator is very sensitive, so do use dual rates (they weren't available in the radio systems back then), it performed very well on single engine performance (I even had the left quit on take off once and was able to do a 180 turning toward the dead engine (it helps), then lowering gear, deploying flaps and having a great landing, the engines have quite a bit of outward thrust, do use as much as it is called for in the plans, it works.
It is one fast and beautiful twin airplane, remember to use dual rates, this bird can be overly pitch sensitive if too much throw is used, by the way, mine weighed 12 lbs. ready to fly, I had to use a lot of nose weight to balance it properly, this is one airplane that can be very unforgiving if not balanced properly, balance it so its nose is down by about 15 to 20 degrees. Wishing you the best of times with your new Cessna!

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