milfalcon1

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Im building the B-17 A and C versions, converted from the Royal B-17 E version...Im also using Os Wankels type 1 so I can keep the carbs under the cowls and the exhaust plumbed thru an inline tubular muffler out the same place as the real B-17s are...My problem is its coming along very nose heavy, due to the lighter tail feathers and thinner fuse, so i had to mount everything towards the back thru the bombay doors....The CG is being closely scrutinized here... My question is does anyone know how larger scale planes fly when slightly nose heavy?... I hate to have to add too much lead in the tail to compensate, overall weight is getting up there...

I-fly-any-and-all

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try rcroyal.com for some good info. All planes regardless of size will fly the same way whether it be nose heavy, balanced, or tail heavy. The difference is with the bigger planes hey are more graceful and they aren't as wild on the controls (unless they are designed for 3d) as say a .25 sized combat plane. Being nose heavy for the royal b-17 as I have found from sites such as rcgroups, rcscalebuilder, and rcu, is that it seems to be nose heavy due to the balance point on the plans being something like 22% to 25% of the way back from the leading edge where other planes balance 1/3 or 33% of the way back. The most likely reason for it being nose heavy is that it is true to scale. Also from what I've read the cedar hobbies now defunct, b-17 arf was nose heavy and they placed the servo's in the tail to save weight and avoid lead weights. For a plane like the b-17 I would reccommend it be slightly nose ehavy as it isn't a 3d plane and in an engine out or retract failure situation you are not going to want to be tail heavy as it will most likely end in disaster.

maverick pro

hey...im not 100% sure but arent the wankels heavy compared to a regular .15-25 size engine? im also building the royal b-17 and havent yet decided on engines but to keep cost down im going 2 stroke. from what i have heard wankels eat lots of fuel but ive never used one so i could be wrong.

thanks...mike

I-fly-any-and-all

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got pics?

maverick pro

sure...not the greatest though. since these pics the fuse glass has started and the stabs have been glassed.

thanks again...mike

jaka

Hi!
Sorry! But those OS Wankels are not suitable in a 4 engined scale plane (or in a twin).
First they are too heavy, second they are not reliable enough and third, they are too powerful!

More suitable engines for the Marutaka B-17 would be OS LA.15 engines or OS FP .20 engines.These are dead reliable engines!!! The good thing with those engines besides being so easy to handle and reliable, is that they require less fuel which means smaller tanks, and also they require smaller engine mounts which means less weigh...See the positive weight spiral!?

I-fly-any-and-all

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You can NEVER have too much power!

swede5

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You can NEVER have too much power!
[/quote]

Oh???????????????? [:-]

Until you watch the wings snap in half from a high G turn as a direct result of too much speed/power ....................

I-fly-any-and-all

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Uh hey we can have excess power little one but we just maintain proper use of it by only going full throttle when in a tight spot and I highly doubt he is going to try 3d flight.

jaka

Hi!
Being a pylon racer at heart I like fast flying planes with power full engines...but flying scale planes isn't about flying fast. It's about flying at scale speed (observed and noticed) and doing that you have to build light and have adequate power, not too much and not to little power.
Having way too much power often means large engines, larger tanks, larger engine mounts, more massive construction...see the negative weight spiral.

Bob Paris

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Hi Guys,
I have the Royal B-17 kit, with the cocpit kit too and I also have run the OS .30 Wankel. I will agree that 4 Wankels on this kit would create a way over powered B-17. Its simply more then double the power you need to fly this model. The Wankel is a very thirsty beast and with small nacells to put your glow fuel in...you will not have much flight time. Maybe five minutes at best if your lucky with the Wankel. I had good luck running mine and the transition from dead idle to full power is better the with an electric powered model...unbelievable fast. The Wankel is also more heavy then a 2-stoke .20, which is what I suggest you use. I have 4 K&B .18's for mine...if I ever get around to build it. But any good .15~.20 2-stroke is all the power you need for this kit. The kit flys quite well, and if your lucky enough to have retracts for this model, you will have a very sweet flying scale model. I helped a guy build this kit over 25 years ago and through this experience...bought my kit. I was amazed at how well the model handled in the air, and she almost will land herself. My buddy put split flaps on his model...but really not needed.

Good luck in your build,
Soft Landings Always,
Bobby of Maui

jaka

Hi!
Agree fully! The OS wankels are nice engines in there right environment , but not in a multi engined scale plane.
I would use OS .15 La engines if it was my model swinging 8x5 or 9x4 APC props. Or my own 3 blade carbon fiber props(10x4,5) cut down some.

nchrome

sorry guys but l kinda differ from you l think the OS 26 fourstroker is even better cause of the sound and the power for a more scale prop. Plus with onboard glow you will never have an engine out situation. l have six of these and am looking for two more for my B-24. Can't wait till l have my wing B-17 done and ready to fly slowly but steady l'll get her done hopefully this year and maybe have it down to bomerfield

jaka

Hi!
I agree that the OS FS .26 are nice engines and that they sound good and are dead reliable. I use two of them myself in my Marutaka DC-3. But... I think they would be a little too powerful for the B-17. at least if you want to fly a slow, gentile docile plane (like a 2m span sail plane). That's the way my DC-3 flies!
OS 15 LA would just a be a better choice in the B-17.

I-fly-any-and-all

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any new pics?

maverick pro

of mine or milfalcon1 b-17?


mike

I-fly-any-and-all

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either.

maverick pro

ive gotten more work done since these photos. i will try and take more soon.

mike

I-fly-any-and-all

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looks great! are you going to glass? Also did you add flaps?
Also you are scratch building this right? Did you have to make a lot of templates or did you have a kit you duplicated?

maverick pro

hi...in these pics its been glassed with 1/2 oz cloth. it was built from plans and laser short kit. built scale split flaps as the plans do not show them. the are also in the pics to to the side.

thanks...mike

I-fly-any-and-all

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Falcon hows the build coming along? I know one of you guys, I dont remmeber who, sold their plane.

maverick pro

it was me that sold the b-17. found a plane rtf that i wanted more so i sold it. going to build a bigger b-17 one day.

mike

I-fly-any-and-all

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Come on lets see that beautful b-17 with those o.s. wankel rotary engines in it!!!!!!!!

And death to the naysayers who want to put down the idea of using the wankels!

Bob Paris

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Hay I-fly-any-and-all,
Have you ever seen the Royal B-17 ? The Wankel engine has the power of the .40 2-stroke, and drinks fuel like a .60. I have seen the Royal B-17 fly with several different engines, from Fox .15's (plenty of power here), OS .20's and K&B .19's. I guess if you would be happy with 4 minute flights and the ability to hover...and also with nearly two grand to spend on engines...the Wankel would be a good choice to put into a Royal B-17. The Wankel will fit into the Top Flight DC-3...I've seen this, but placing four Wankels into a model with the equivilant of 1.60 for power is just nuts. But if you have more money then brains...and need to hover a B-17...why not.
Soft Landings Always,
Bobby of Maui

I-fly-any-and-all

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ever hear of using restraint on the throttle?
And if he wants to fly it with excess power let him.
Are you jealous because the royal line of kits maintained true scale accuracy?
He is simply just adding more scale features to complete a true to scale air craft.
Also I hear you curb kickers nag and nag about the excess power and mass fuel comsumption, put your money where your mouth is and show us the statistics .......