Pronto Build

[Mojo]

Before building my ClevelandAirline Corsair, I thought I would scratch-build something fairly simple.

After reading this thread, I decided that the Pronto fits the bill nicely.

The above thread provides enough information to get started, but additional digging overturned some dwg's that someone had created. The dwgs are odd in some ways, but marrying those with the original Dave Robellen plans allowed me to come up with my own set of plans.

My Pronto is very similar to the original Pronto, but with ailerons to boot.

To get started I drew up the rough plans (pictured). They are a work in progress, but I already have enough to build the wings.

I then decided to employ the "Constant Chord" method for wing rib creation.

Basically I traced and then glued the outline of a full-size wing rib onto a piece of plywood. I then cut it out with my jigsaw and the repeated the whole process. I ended up with two plywood wing ribs.

I then traced ten ribs from the blanks onto some 1/8" balsa. I traced from the blanks, because I want the outline to be a bit big. I then quickly rough cut those on the jigsaw. Precision is not that important, you just have to cut them outside the lines.

Taking the stack of ribs, I sandwiched them between the plywood blanks and drilled two holes in the stack with my drill press. I then ran two nuts and bolts thru the stack and tightened it up. You can see the stack pictured below.

I was then able to use my Microlux disc sander to sand the entire stack to the size of the blanks.

They turned out really well, except for the spar slots. You can see the end results pictured. The spar slots were a bit tricky. Cutting them with the jigsaw was too imprecise. I need to come up with a better way to do them. That said, they are still pretty good and all together it took me under a half hour to cut them all out.

Anyhow, I will post more about the Pronto as I build it.

-Mojo

[Wildflyer]

The Pronto is a great flyer, I had the 3 ch one. I had 100's of flights on it before it fell apart from castor oil getting into the center joint of the wing in mid air. The fuse doesn't fly very good without the wing so it didn't survive either.

I am going to build an electric one, with two wings, one with ailerons, & one without, make them look exactly the same, should be fun .

[Mojo]

I cut out my fuselage sides from two pieces of hard 1/8" x 3"x36" balsa.
I traced a pattern from plans and glue sticked it to one of the sheets. I then blue taped the two sheets of wood together and scrollsawed the shape.

The resulting fuselage sides are 2 7/8" x 34 1/2" long

As a bonus, I ended up with two perfectly fitting 1/8" ribs (pictured). I also test fit the ribs I cut previously, and they fit nicely!

So, after marking off formers, should I cut (lightening) holes in the fuselage sides to reduce weight?

[Mojo]

The original plans call for doubling the front portion of the fuselage with 3/16" balsa. The area to be doubled is the area between the F1 and F2 formers.

To make the doublers, I simply traced the front portion of the fuselage onto some 3/16" balsa and cut it out with the scroll saw.

You can see the doublers, formers, and the fuselage sides in the pictures.

Note: I decided to go ahead and drill lightening holes from F4 to the tail.

After gluing and clamping the doublers, I positioned the formers and glued them in place. I will probably brace the formers with 1/4" triangle stock.

[road king 97]

Originally Posted by Wildflyer

The Pronto is a great flyer, I had the 3 ch one. I had 100's of flights on it before it fell apart from castor oil getting into the center joint of the wing in mid air. The fuse doesn't fly very good without the wing so it didn't survive either.

I am going to build an electric one, with two wings, one with ailerons, & one without, make them look exactly the same, should be fun .

Dave who desighned the pronto had a biplane called the parakeet ,it is on my build list too and i have the plans.I tried to upload the pdf here but it keeps failing sooo if you want the pdf pm me a email adress so i can send it to you. Here is my pronto surpreme i built it nitro like the one i had 20 years ago with a k+b 20 on it. joe

[Mojo]

Originally Posted by road king 97

Dave who desighned the pronto had a biplane called the parakeet ,it is on my build list too and i have the plans.I tried to upload the pdf here but it keeps failing sooo if you want the pdf pm me a email adress so i can send it to you. Here is my pronto surpreme i built it nitro like the one i had 20 years ago with a k+b 20 on it. joe

Road King, your Pronto Supreme looks great. Please post more pics if you got them. Thanks!

[road king 97]

http://www.rcgroups.com/forums/showthread.php?t=1401154 Mojo here is a whole thread with guys building prontos electrict and nitro .Banjo was a friend of daves and gave out the plans free to continue the legend. Iam cracksmeup on rcg and you can see a couple more pictures of my build and a bunch of others.You can also get daves parakeet pdf there if you want dave's biplane plans. joe

[Mojo]

Originally Posted by road king 97

http://www.rcgroups.com/forums/showthread.php?t=1401154 Mojo here is a whole thread with guys building prontos electrict and nitro .Banjo was a friend of daves and gave out the plans free to continue the legend. Iam cracksmeup on rcg and you can see a couple more pictures of my build and a bunch of others.You can also get daves parakeet pdf there if you want dave's biplane plans. joe

Road King, thanks for the link. I found the parakeet plans too, thanks again!

After reading the entire thread, all 32 pages, I am rethinking adding ailerons to my Pronto. I may build the first one 3 channel only.

It sure seems like a lot of people had fun with the original design. I was just going to add ailerons to that design, but apparently, the super pronto is modified a bit more to adjust for the ailerons. I may need to do a bit more planning and revisit the thread again, as opposed to just adding 1" strip ailerons.

[road king 97]

Originally Posted by Mojo

Road King, thanks for the link. I found the parakeet plans too, thanks again!

After reading the entire thread, all 32 pages, I am rethinking adding ailerons to my Pronto. I may build the first one 3 channel only.

It sure seems like a lot of people had fun with the original design. I was just going to add ailerons to that design, but apparently, the super pronto is modified a bit more to adjust for the ailerons. I may need to do a bit more planning and revisit the thread again, as opposed to just adding 1" strip ailerons.

I added 1 1/2 ail to my surpreme and i dont think it helped .There were a couple that changed it to a ail wing and i think i saw a small drawing in the thread somewhere. The surpreme was always ment to have ail and the fuse is a little different in places but not that different. I have had a blast with mine just like i did long ago. You could make two wings for it easy and fly it both ways as a 3 or 4 channel. Just make sure you mount your servos high in the fuse e to clear your tork rods for the ail wing and its all good. I used mini servos on my nitro pronto surpreme but i striped my ail servo and went to a stronger servo. joe

[Mojo]

Sorry, I didn't quite follow you.

Originally Posted by road king 97

I added 1 1/2 ail to my surpreme and i dont think it helped

It didn't help? Meaning that you modified the original pronto to have a 1 1/2" aileron and were unimpressed with the overall aileron performance?

Thanks!

-M

[road king 97]

Originally Posted by Mojo

Sorry, I didn't quite follow you.



It didn't help? Meaning that you modified the original pronto to have a 1 1/2" aileron and were unimpressed with the overall aileron performance?

Thanks!

-M

My pronto surprmeme had 1inch strip ail and i made them 1 1/2 wide and at the fuse just 45degreed back in. I have a friend here with the same plane and mine does not roll any faster with the extra 1/2 inch. I have been flying over 30 years and i would get bored with just rudder and elev so ail is a must have for me.I will check my print and see how much incidence on the ail wing has. joe

[soarrich]

Originally Posted by road king 97

I have been flying over 30 years and i would get bored with just rudder and elev

The cure for boredom is do it rudder only!

[road king 97]

Originally Posted by soarrich

The cure for boredom is do it rudder only!

I have flown rudder only when i was younger ,more throttle to climb less to make it come down . I still have a orbit radio with tubes ,push the button once it goes left push it twice it go's right. It was no fun then and i dont think it's gotten any better with age. lol joe

[Mojo]

After gluing the formers, I added some bracing and ensured the tail of the fuselage was straight before gluing.

Next I sheeted the top of the fuselage and sanded it smooth.

Kinda looks like a coffin, eh?

[road king 97]

I like your magnet building table ,i have been putting off building one for 10 years . I think its the only way to go . I ran my front top sheeting all the way out to the out side of the fuse and cut the bottom on a angle to meet it ,this way when rounding over the edge with sand paper or i used a balsa planer to knock it down fast you have something to plane and sand to make it round . joe

[Mojo]

Originally Posted by road king 97

I like your magnet building table ,i have been putting off building one for 10 years . I think its the only way to go . I ran my front top sheeting all the way out to the out side of the fuse and cut the bottom on a angle to meet it ,this way when rounding over the edge with sand paper or i used a balsa planer to knock it down fast you have something to plane and sand to make it round . joe

Thanks. The building table is a work in progress. I bought the 1/8" steel from a scrap yard. I was a bit surprised to learn that it was 65 pounds!
That said, it is very flat. I had to scrape and paint it, but I am pretty happy so far. I am building the fixtures as I need them from some old laminate flooring.

As far as the sheeting is concerned, I figured I would round the fuse sides into the sheeting. We'll see when I get there, but I may need to add some filler or additional balsa to make the transition smooth. Although, I do kind of like the coffin look.

-M

[road king 97]

lol you can tell by my avitar that this old biker is into sculls and coffin's'

[Mojo]

For the ailerons, I am debating whether to use an aileron linkage controlled by a single servo, like so: http://www.headsuprc.com/servlet/the...-System/Detail, versus a dedicated servo in each side of the wing. The original plans use a single servo linkage.

I would appreciate any advice on this manner.

[road king 97]

I used a single servo in the middle cause the wing ribs are not very tall. If you got real small servos it could work but i was trying to keep the weight down under two pounds and the extra servo mount and servo will add to the weight. There was plenty of room in my fuse and i have a reciever flat battery in there too cause its nitro.On this one i think its up to you. I can take a picture of my print and post it for you if you want ? That is the same set i used in mine . The one older picture is from banjo in the pronto thread and shows barn door ailirons .My wing ribs are semetrical ribs and not flat like yours.The servo is shown in the bay over to one side so you don't cutthrough the center ribs. Btw I have a bolt shown in the picture and dont use rubber bands for my wing .Hope this helps. joe

[Mojo]

Thanks Road King! That's good info. I am going to go with the single servo setup. I received my motor from headsuprc and hope to make more progress this weekend.

[road king 97]

Originally Posted by Mojo

Thanks Road King! That's good info. I am going to go with the single servo setup. I received my motor from headsuprc and hope to make more progress this weekend.

Anytime my fellow pronto builder ! I think the single servo set up is the way to go . joe
.

[Mojo]

The wing build was pretty quick. I'm really enjoying building with magnets. It makes for very straight builds.

That said, you have to be mindful of is choosing very straight wood.

After building the second wing, I noticed it had a slight twist in it (<1/8"). I think it is from a slightly warped spar. Anyhow, I have soaked it in ammonia and am clamping it to the board. Hopefully that will remove the twist.

[road king 97]

She looks good mojo ,iam liking that magnet setup also but it's either more balsa and foam sheets or magnets and metal board and i need more balsa and foam more now. I sold some old 70's slot drag cars out of my stash today and it gave me plenty of new cash for the hobby.

[Mojo]

Well, the pronto build is still trucking.

I am embarrassed by how long it is taking, but at least it has progressed to the covering stages.

I was doing some reading about airfoils here:

http://www.airfieldmodels.com/inform...t_airfoils.htm

and it occurred to me that the flat bottom airfoil, that Paul warns against, appears to be the same airfoil that the pronto uses.

If you look at the original plans (linked here), it sure looks like a flat bottom airfoil to me.

The newer plans, super pronto with ailerons, are more of a clark-y.

What type of airfoil does your pronto have?

How does it fly? Difficult to trim?

Cheers,

M

[road king 97]

Originally Posted by Mojo

Well, the pronto build is still trucking.

I am embarrassed by how long it is taking, but at least it has progressed to the covering stages.

I was doing some reading about airfoils here:

http://www.airfieldmodels.com/inform...t_airfoils.htm

and it occurred to me that the flat bottom airfoil, that Paul warns against, appears to be the same airfoil that the pronto uses.

If you look at the original plans (linked here), it sure looks like a flat bottom airfoil to me.

The newer plans, super pronto with ailerons, are more of a clark-y.

What type of airfoil does your pronto have?

How does it fly? Difficult to trim?

Cheers,

M

Mine is the pronto surpreme and has a different airfoil and ail so it;s not the reg pronto and it flys great but i have owened one of the pronto's with no ail and it flew fine with a flat bottom wing .The main thing is to keep it light witch ever one you build . http://www.airagestore.com/planes/pl...o-supreme.html