BERUSTY

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Bridi Dirty Birdy 40 Plans?

Does anyone have an oriinal/pdf/copy of the Bridi Dirty Birdy 40. There is one on Buy-bay at $150+ and it is 6days to go!


Rusty Dose
Team Futaba
Team YS Parts and Service

Pattern One

My Feedback: (73)

Rusty,

I think I have an original kit that I could make a copy of the plans from if you are interested? I'm traveling and can check my inventory later this week.


Leo

anuthabubba

My Feedback: (102)

Yeah. That's pretty high. Got mine for $89 a few months ago.

Now have quite a collection of Joe Bridi stuff: Tweedy Bird, DB 40, DB glass/foam, 2x DB balsa, Escape, Great Escape, Utter Chaos, UFO plans and F/G fuse (thanks Rustys) and Trainer .60 plans. Would like to get an RCM Basic Trainer (.19) kit or plans.

Terry in LP

petec

My Feedback: (58)

Leo,

I had FedEx kill my last set of plans when I was sending them to be copied. If you have a set and can get them either hard copied or a PDF I'll be more than happy to pay you for your time and trouble.

rainedave

My Feedback: (1)

I don't know how different the .40 is from the full-size DB, but I can scale the plans down and post a copy. What is the span of the .40 DB?

[Terry, I emailed the basic trainer plans to you.]

David

Jim_Purcha

My Feedback: (8)

Hi David, I have a copy of the DB40 from another modeler from the site. The DB40 had a fibreglass cowl, and the rudder and stabilzer are constructed from sheet balsa.

Jim

anuthabubba

My Feedback: (102)

Thank you rainedave!

Terry in LP

doxilia

My Feedback: (3)

David,

I believe it spans 58". The model sounds like its a large Tweedy Bird (sheet tail feathers) rather than a small Dirty Birdy. Just because airfoiled tail feathers are cool, I prefer your DB 20 plans (scaled 60) over the TB plans.

David.

anuthabubba

My Feedback: (102)

Okay.

Up late. Dug out the plans and the span is 58". The length is 50.5" and the area is 565sq". The stab is flat.

Terry in LP

rainedave

My Feedback: (1)

In that case, you could, I suppose, use these scaled-down plans, and simply build a sheet stab.

Right-click and "Save link as..." dirtybirdy-40.pdf

David

BERUSTY

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Bridi Dirty Birdy 40 Plans?

You guys are awesome...thank you. It would probably be better a little larger for today's more powerful motors and the ability to enlarge the prints at Kinko's/FedEx maybe 10-15%.

My wife (oliveali426) really wanted me to have the kit...no, she doesn't care either way...and pushed the thing to $213.50. I will be very surprised if it went for over $251.

Rusty Dose
Team Futaba
Team YS Parts and Service
Looking for a Bridi Escape kit!!!!!!!!!!!

AndyKunz

I agree that a larger plane is OK, but 10% enlargement is a LOT. You're talking about making the plane 30% heavier (based on volume).

Be careful. Remember that a linear enlargement causes a cubic increase! Taking a plan to 110% means 1.10 x 1.10 x 1.10 (=~ 1.3). 15% is even worse!

Andy

rainedave

My Feedback: (1)

I think 58" is already on the large size for a typical forty.

This is the most powerful sport .40 I own:

http://www.rcuniverse.com/forum/fb.asp?m=8181884

But, with a pipe, I think it would fly a 58" DB fine.

Another good .40 choice is the SF.40-P with #46 carb and pipe.

If you go .45 or up it's a totally different story altogether. But, I still wouldn't scale it up. Remember, the sixty-size Super Kaos has a 58 1/2" span.

David

BERUSTY

My Feedback: (3)

Enlarging old school models to better capture available power...

My personal experience is the venerable Gator Flea. My scratch built model powered by an O.S. 46 with a tuned muffler (from the pylon guy) was soooo over powered it was silly...unless 500' figure M's are too small. Even the hottest 95 degree 900% humid day was 1/2 - 3/4 power for all but the 750' loops. I probably could not see the tiny Gator Flea at the top of a 750' loop, but one can understand my point.

Rusty "2-Cents" Dose

rainedave

My Feedback: (1)

I agree 100% with your approach to utilizing the largest possible airframe with a given engine. In other words, I would also rather fly a larger plane than fly a smaller, grossly overpowered plane.

My ST Schneurle Bluehead is making 6 1/3lbs. of static thrust on the ground without a pipe. If the 58" DB was built between 5 and 5 1/2lbs. that engine would not be overkill, IMO. Now, if the model came out over 6lbs, the pipe would probably be necessary.

I guess it's not so much the span, but the AUW.

David

anuthabubba

My Feedback: (102)

I always like to see 100sq" per pound on a midsize plane. Don't always get it but can usually get close. More area is good. Now this is on what was considered .40 to .90 size planes 20+ years ago. Not like today where the norm is a .90 on a 6 pound/.60 size plane.

Terry in LP

doxilia

My Feedback: (3)

David,

That's a great reminder! 6.5 lbs of thrust... wow! I see that you now have a pipe on it with a particularly nice fuel tubing arrangement . You'll probably get to run it before I do if you haven't already. Please let me know your results. Hopefully I'll be able to run mine in May if I just get my A&& down to finishing up the Tsunami.

As a point of interesting comparison, my Tsunami has very similar specs to the DB 40 - 1/2" more of span and 547 squares. My AUW sans pipe (but with header) and without a couple of rudder linkages and horns stands at an even 2.0 kg or 70.5 oz (4.4 lbs) - this is one light airframe! I expect I should be able to easily have it on the flight line, wet, at a hair over 5 lbs.

At some point I considered a YS 46 SF or originally an OS 45 FX but piped, those engines would probably deliver the same kind of performance to Rusty's Gator Flea - that is; excessive. With pipe, I imagine the ST S40's should be able to produce in the vicinity of 7 lbs of thrust!

Now... is anyone considering hovering their DB 40!? (Sorry, couldn't help it).

David.

doxilia

My Feedback: (3)

Good point Andy.

A 10% linear enlargement of the DB 40 would bring the span from 58" to 63.8". The DB 60 has a span of 64" so the 10% would essentially take the model from a 40 size to a 60 size. The converse would also be (roughly) true - 58/64 = 90%. A 4-5% linear increase would probably be better suited to the 45-50 class engine for a DB with a 60-61" span.

As an example, the Aurora 45 has a 56" length, 62" span and 667 squares with an AUW of about 6.6 lbs (perhaps less). This is a YS 45, Webra/OS 50 class aircraft. Wing chord is of course also important to note in the classics as there are models such as the Deception and the Arrow which, compared to the Japanese designs, have comparatively short spans but wide wings. The Deception, for example, only has a 63" span (1" more than the A45) but 750 squares! The Arrow 40 has a 56" span but a whopping 618 squares! Expected AUW of the Arrow is ~5.5 lbs - this would be a good candidate for a 45-50.

So we have 45-50 class aircraft with 56-62" spans and 618-667 squares. I would think that these provide good lower and upper limits for the class of powerful 45-50's (still) available today.

Aside from gut instinct (sometimes referred to as design experience...[8D]), wing cube loading might actually provide a useful proxy spec for scaling purposes:

http://www.flyrc.com/calculator.shtml

My Tsunami has a wet square loading of ~21.5 lbs/sq ft and a cubic loading of ~11.

David.

BERUSTY

My Feedback: (3)

Dirty Birdy 40 kit

Price discovery would reveal that with less than a few hours remaining one will need at least $270 to have an original kit.

Rusty Dose
TF
T YP&S

anuthabubba

My Feedback: (102)

"...with less than a few hours remaining one will need at least $270 to have an original kit."

Maybe to have ... that particular ... kit. If there's one thing I've learned about shopping classified pages on the www, it's that there will be another one (of whatever you are looking for) along eventually and the price will be different. You gotta be watching for those deals though. Next week someone might list one for $75 BIN and it will be snagged before most of us even see it.

Terry in LP

BERUSTY

My Feedback: (3)

Price Discovery Dirty Birdy 40

Current price for THAT Dirty Birdy 40 was...$291.

By coincidence, one of our pals and I were "pushing' the price to crazy levels. I am o****6 or o****i on the internet based auction site. You are welcome to call or (PM) me for my upper price limit. We all may benefit (pay less) for your curiosity.

Rusty Dose
Team Futaba
Team YS Parts and Service

BERUSTY

My Feedback: (3)

Dirty Birdy 40...NO WAY!

I visited a garage in Central Illinois on Saturday morning and left with (2) NIB Bridi Dirty Birdy 40's.

Rusty Dose
Team Futaba
Team YS Parts and Service

delsoft

I have the Bridi Dirty Birdy .40, unopened kit here along with a Supertigre .40/with muffler (never used)

anayajc

Hi rainedave


Thanks for this information, I was looking this plans by days in the web.


I just print the plane DB 40, that you post here, in TXT file, The plans look good, I going to start to build maybe this Weekend, so I am Asking you if the plans have no problem of scale.

I mean is ok the plans

Thanks