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Hostetler Pitts S1-11 - 7/4/2003 7:03:02 AM   
RENORACER



Posts: 53
Joined: 10/12/2002
From: Reno, NV, USA
Status: offline 		Hey All,

Going to start building a 35% Pitts from hostetler plans, (purchased here on RCU) and I have a couple Questions.

First off, The plans state finished weight at 22-26 lbs. I am going to lighten it up a bit as all the wing ribs are shown solid and I am going to cut lightening holes in all but main ribs for mounting.

Also in some of the fuselage will be some lightening done. All up finished weight I am shooting for is around 18 lbs. or so.

What servos and engine size for this plane?

Would like to do a conversion engine as I am on a tight budget .

I appreciate any and all info given. Has anyone here built this plane, and if so, what motor and servos did you use? How did it fly?


Thanks in advance, David

RENORACER

PS: I am hand cutting, and selecting all the parts myself. only using landing gear ,cowl ,canopy and such from other sources.
       Post #: 1

Hostetler Pitts S1-11 - 7/7/2003 5:25:19 PM   
VoughtF4U



Posts: 359
Joined: 1/4/2002
From: Gray, TN, USA
Status: offline 		I've had the plans for this one for a while. Every now and then I'll drag them out and think about building it but I have too many planes started as it is. I do plan on starting it this winter sometime.

The plane can be set up for simple everyday flying, or as an unlimited aerobat. Decide what you want to do with it, then make your choices for servos and engines.

For power, I am planning on using either a ZDZ 80 or possibly a 100cc twin. You could probably use something as small as a Zenoah G62 and still fly pretty good.

I am planning on using Hitec digital 5945 servos on the ailerons and elevator and a 5735 on the rudder. These servos are standard sized, light, fast and powerful, but expensive. If you want to go cheaper, you can use something like a Hitec Hs-700, or one of the smaller digitals like a 5645. These are anything from $25-$50 each. Definitely use 70 ounce servos or larger.

Should build pretty quickly since it has a low parts count. The main box the fuselage is built around has lots of room for lightening it up without losing much strength. Good luck with it and post some pictures here as you build it.

_____________________________

"Mix ignorance with arrogance at low altitude and the results are almost guaranteed to be spectacular"

(in reply to RENORACER)
       Post #: 2

Hostetler Pitts S1-11 - 7/7/2003 7:57:03 PM   
RENORACER



Posts: 53
Joined: 10/12/2002
From: Reno, NV, USA
Status: offline 		Thanks for the advise. Going to order the cowl, canopy and wheelpants from fiberglass specialties soon. Not going to use the gear farings tho. Found a local supplier for 1/8 in birch ply for door skins @ less than $20 a sheet (4x8) should be good for fuselage box, and will cut extra lightening holes. I also thought about using the same for the front fuse. doubler. What do you think?

This will be my first plans built plane, but looks fairly simple. I will post pics of work when I do finaly start it. May be a couple months tho. Have to finish a Flybaby first. Just collecting parts and info right now for pitts. I plan on cutting all the parts first.

Was also wondering about the tail feathers. Thought about building these from balsa stick(1/4in) and sheeting them with 1/16, instead of using solid 3/8 in balsa. Do you think this is a good idea? or which would be stronger and lighter?

Also, could balsa stick be used for spars in wings without loosing too much strength, if a couple more sheer webs were added? And what about using 3/32 in balsa for all sheeting instead of the 1/8 in.


Thanks for any input.

David

RENORACER

(in reply to RENORACER)
       Post #: 3

Mods - 7/7/2003 9:30:36 PM   
VoughtF4U



Posts: 359
Joined: 1/4/2002
From: Gray, TN, USA
Status: offline 		David,

You hit on a lot of the mods I planned on making. I actually cut out a fuselage box out of 1/8" Luan doorskin. I also cut the ply fuselage formers out of the doorskin material. The problem I had was it ripped more than it cut so the edges were frayed in some spots, otherwise it will work perfectly. I was also thinking about possibly just using some balsa sticks to make the box, adding in some diagonal sticks and not using the ply at all. I will probably use the Luan doorskins though. It will work for the fuselage doubler too. Just make sure you have good glue joints where needed.

I am planning on using sticks to build up the tail and sheeting them with 1/16" balsa sheeting or possibly 1/64" plywood. Probably go with the balsa sheeting. I did this on a Lanier Giant Stinger I am building for my dad and it definitely came out strong and light.

I will use Basswood sticks for my spars. Balsa could possibly work if you picked perfect sticks out. I wouldn't feel comfortable with balsa spars unless I strengthened them with some carbon fiber or something. The weight you will save isn't worth the risk of folding the wings up to me. I know there are some guys out there that could make it work and end up being stronger and lighter, but not me.

I also plan on using 3/32" sheeting because I have a bunch of it and I always end up sanding the 1/8" balsa down anyway. I will not be using the gear fairing either since most of the -11B pitts i have seen don't have them.

_____________________________

"Mix ignorance with arrogance at low altitude and the results are almost guaranteed to be spectacular"

(in reply to RENORACER)
       Post #: 4

Hostetler Pitts S1-11 - 7/8/2003 8:51:52 AM   
RENORACER



Posts: 53
Joined: 10/12/2002
From: Reno, NV, USA
Status: offline 		Seems like we both have the same ideas on building this Pitts. The plywood I am going to buy is supposed to be quality birch that I believe is 5 ply . I havent seen it yet, only talked to someone on the phone about it. I dont think it is the luan you mentioned.

As for the spars, I am probably going to go ahead and use basswood. After thinking about it, you are right. It just isnt worth taking any chances here. Looking at a G62 for the powerplant. Found one pretty cheap. Has some damage at front of case that has been repaired. but worse case , I may have to get a new case. The price is right at about 125.00 Far cheaper than a new one.

Would be pretty cool to compare notes as we both build these birds. I'll be posting results here as I go. Would love to hear from anyone else that has built , or is planning on building one of these.


By the way, Love your screen name. Its one of my favorite planes.

(in reply to RENORACER)
       Post #: 5

Hostetler Pitts S1-11 - 7/18/2003 8:05:16 PM   
Darrinc



Posts: 1028
Joined: 1/22/2002
From: Piqua, OH, USA
Status: offline 		I love aerobatic planes and there is nothing better than a lite one, but biplane naturally lend themselves to coming out heavier than expected, so you must go to the n'th degree when building. It's a great challenge that pays off in spades in the air, but it is difficult to do less, and you really have to focus to not build like you always have, or fall into the famous, "Oh, just a little extra here". They all add up quickly.

Just a few lightening tips that I have been using for several years and they work very well. Bring your scale to the hobby shop when you get wood.

Balsa longerons:

Use the third lightest of your balsa sticks to frame up the fuse.
Use unicarbon in high load area's. Remember, the shape of the fuse gives more strength than the individual pieces.

Balsa spars:

use the second lightest set you can find, 3M unicarbon to outside face of the spar, then use thin CA here when you apply the sheeting.

Stick build tail:

Use the lightest of your balsa sticks to frame up the tail, sheet with 1/16" x 1/2" over all sticks (creates a I-Beam) apply unicarbon (same as constructing the spar) around edges of frame if it needs extra stiffness. Stick build outer cabanes.

Contest Balsa:

Use everywhere. 8lb density is good for all around use. Fuse box and doublers would be fine with this wood, spread the CA around the edge, down the center, then in a X pattern when installing any doublers, this will give you both max longitudal and torsional strength for the weight.

Also works well for shear web in the wing, double w/doubler it at the center, double two ribs out, single for rest of wing, stop at third rib from the tip. (there is very little load there)

Do not use ply: (except formers)

No 5-ply. Use 1/4" endgrain balsa, sandwiched in 1/64" ply for firewall landing gear plate and anywhere else you use 5-ply. I have 1/4" endgrain if you need some.

Use1/8" lite ply for formers and cut them out to have 3/8" width around edges.

Do not use epoxy:

Flex CA works wonders, its holding my DA100 in my Cap. Let set for about three minutes, then kick it. It's light and strong!

Use uni carbon:

You can place it just where the load is, that way your not carrying aound dead weight. In the long run it will be cheaper than 5-ply aircraft ply since you only need to use a 1/4"~3/8" wide strip, so that uni that you buy will go a long way.






Best of luck and keep flying!

< Message edited by Darrinc -- Jul 18 2003 3:21PM >

_____________________________

"Make everything like your going to make the front page of NASA Tech Briefs"
Go Team Orange! Darrin R Cash

(in reply to RENORACER)
       Post #: 6

Hostetler Pitts S1-11 - 7/19/2003 10:26:42 AM   
RENORACER



Posts: 53
Joined: 10/12/2002
From: Reno, NV, USA
Status: offline 		This sounds really good. Light weight and strong.

Not familiar with 3M unicarbon. Do most hobby shops carry this? Or is there somewhere I can get it on line.

On the tail surfaces, are you saying not to totaly sheet the structure? Only use Cap strip type building , and then layer it with unicarbon?

The fuse is made up of a box, with formers and stringers around out side for shape. Can the box be made of AC grade mahogany? I found some in my dads garage from when we use to build real airplanes years ago. very clean 1/8 in stuff.


Do you have any images you can post reguarding the firewall build?

This is my first plans built plane and I want it to turn out right. Still not sure of power source. Possibly a G62. Do you think an old Quadra 42 would be ok . have one of those. Nothing bigger at this time.


Thanks for the comments. Greatly appreciated.

(in reply to RENORACER)
       Post #: 7

RE: Hostetler Pitts S1-11 - 12/10/2003 12:06:51 PM   
c-grain


 

Posts: 209
Joined: 11/10/2003
From: blanca, CO, USA
Status: offline 		Renoracer,before you even consider trying to lighten this design, decide which engine you will use!
The big-banger engines commonly used to power this size plane are also big on VIBRATION! You must plan for this. Although you may save a few bucks going for a 4cu.in. engine the 6cu.in. would probably be better. The smaller engine will probably be too light & require a bunch of lead bolted to the firewall to balance-canceling-out your efforts to lighten the ship. As for the holes in ribs,you won,t save much relative to a plane this size-better-off using "c grain balsa". Darrinc has some good advice-Have a scale at the bench! weigh all the ribs first and use them in order of wt. That is-heaviest at center to lightest at tip. This does save counter wt. at the light tip during lateral balancing when plane is finished. You do balance laterally don,t you? anyway I have the 45% version of the pitts about to go onto the board. Remember,this is a big airplane-don't try to build it like an electric. Also, think about the fact that you can easily subject this thing to over 10G's- 20lbs.becomes 200! cheers-good choice of project.


balancing lead in an aircraft just showes how well you did your homework

< Message edited by high planes flyer -- 12/10/2003 12:18:38 PM >

(in reply to RENORACER)
       Post #: 8

RE: Hostetler Pitts S1-11 - 12/11/2003 3:03:18 AM   
RENORACER



Posts: 53
Joined: 10/12/2002
From: Reno, NV, USA
Status: offline 		Thanks for the advise. I made all the formers and fuselage sides and doublers out of aircraft grade 1/8" mahogany, And Firewall from doubled (laminated) 1/4" birch. Had a bunch left over from my fathers stash in his garage that had been intended on being used for a Bowers Flybaby. Project got sold when about 80% compleat. Guess he lost interest. All cross pieces for landing gear, and upper mount plate's for cabanes are also from laminated 1/4" birch. Decided to build tail feathers from 1/4" x 3/8" balsa, shaped for airfoil, and fully sheeted with 1/16" balsa, and Leading and trailing edges re-inforced with carbonfiber.

Still not sure of powerplant yet, so project has been put on hold. I did get the Cowl, Wheel pants, and canopy from fiberglass specialties. Landing gear and tail wheel assy. to be ordered after the first of the year.

All pieces cut for fuselage except for sheeting,(not glued together yet) weigh about 2 lbs. , looking good so far. Will try to post pics when I get around to the building.

Good luck with your larger version, and hope to see some pics of yours too. I have built many kits in the past, and this is my first plans built plane. I have never built any electrics, all have been gassers . I very seldome have had to use lead to balance , and if I did, it was very little. (less than 2 oz.) in the largest plane, a 90" ws Cub. Only 1/4 to 1/2 oz was used for lateral balance.

(in reply to c-grain)
       Post #: 9

RE: Hostetler Pitts S1-11 - 12/11/2003 1:37:36 PM   
c-grain


 

Posts: 209
Joined: 11/10/2003
From: blanca, CO, USA
Status: offline 		Sounds like you'r on the right track.As for engines-might want to consider the Q-75XL or better yet the Q100XL by Quadra. These are excellent engines,great pwr to wt ratio& not too expensive. As for my project, I'm waiting for balsa&Sitka spruce. Also am having a hell of time trying to find a canopy for this beast-called all the usual places nobody seems to make one for the 45% size. May have to make it myself! Sure would like to see some pics of your bird framed-up!

(in reply to c-grain)
       Post #: 10

RE: Hostetler Pitts S1-11 - 12/11/2003 3:06:28 PM   
RENORACER



Posts: 53
Joined: 10/12/2002
From: Reno, NV, USA
Status: offline 		I am planing on using an engine in the 80-100cc range. Would like to go with a twin, as I have read that they ar a lot smoother running than the big singles. Will have to wait till tax return time befor I can think about buying. Have seen a couple on ebay go for less than $700.00 recently. Both were low time 3W- 100cc twins. May even find a good used one here on RCU when I am ready.

I have decided to use some good Spruce for the wing spars for strength, but have not made any ribs yet. Most of the 1/8" balsa I have is very lite contest grade, and not very goog quality. Will probably leave these peices for the sheeting, and order some new stuff just for rib material.

(in reply to c-grain)
       Post #: 11

RE: Hostetler Pitts S1-11 - 12/12/2003 12:20:55 AM   
Darrinc



Posts: 1028
Joined: 1/22/2002
From: Piqua, OH, USA
Status: offline 		Sounds like with the building techniques that you have used that your plane will finish out around 28lbs, so you should go with a ZDZ 80 single which will get you down to 27lbs and it is in your price range.

There is no place in models, other than firewalls and landing gear plate, for anything other than balsa. I just use composites to replace the 2 parts that you would use ply on. Spruce spars are 30 times stronger than you need and weigh a heck of a lot? Why do you need strong wood for the ribs? What do ribs do? There is your answer!

I have no idea why people build so heavy? I'm not trying to scold, just to understand why. I seriously do not see the logic in adding weight. If you build it heavier, it will take a big hit, but if you build it lighter, there is not the mass to give it the big hit.

Oh, and lighter flies better expodentally. You can also use a cheaper engine and cheaper servo's.

< Message edited by Darrinc -- 12/11/2003 4:26:20 PM >

_____________________________

"Make everything like your going to make the front page of NASA Tech Briefs"
Go Team Orange! Darrin R Cash

(in reply to RENORACER)
       Post #: 12

RE: Hostetler Pitts S1-11 - 12/12/2003 5:07:06 AM