Jan Hermkens B17
 

Have a set of Jan Hermkens B 17 plans Im just itching to start. WS-10 feet, length 90". The plans formers list 3 types of plywood....Lite ply, birch ply, and some are "balsa ply". Now I have never heard of balsa ply before....what is it ? The plans are from the Netherlands...so I don't know if they have some different materials there that we dont find here ?

RE: Jan Hermkens B17
 

Balsa Ply wood, is just what it says. You can easily make by using balsa crossgrain, and glueing with epoxy. Much lighter and stronger than lite ply. I have never checked to see if anyone has it available, because I have been making my own for over 25 years. You need a flat surface, and a flat item to lay on top of the lamination after assembly. You can start by making you pieces of course, and then use a slower epoxy, and apply it sparingly, then use a old credit card to squeegy it almost all off.Same as doing a foam wing. You would then sandwich it between two pieces of 1/4" plate glass, weighted, and allow to cure. I use plate glass, because it is flat, and very smooth.

I have stopped using lite ply, as it is not very strong for its weight. It cracks, breaks and is a bad idea. It became popular with kit manufacturers, back when there were still lots of them around, because it would die cut easily and was very very cheap. China still uses it for Barf's, because it is Cheap. I replace all lite ply with balsa of the proper grain and density, as it is much stronger. More expensive though!

The other thing I do, is use lite Carbon Matt on both sides of bulkheads. I first tack the matt in place with some paper glue stick, then lay on the epoxy, and squeegy most of it off. I then use two pieces of plate glass that has been liberally waxed and coated with parting agent. One piece of glass lays on your bench, then put the layed up balsa/ Carbon Matt down on the glass, followed by the next piece of glass weighted down. Makes for some darn strong pieces when cured, and very light weight. It is of course best to do the layup first, then cut the parts out, with a scroll saw, or have them laser cut. Good luck with the seventeen, I'm, sure it will be a beautiful plane when done.

RE: Jan Hermkens B17
 

I have looked every where I know of for end grain balsa, with no luck. Maybe I'll just go with the lite ply.

RE: Jan Hermkens B17
 

The only balsa-ply I know of, that was placed in kits, was generally balsa with thin ply laminated on both sides.

The plans should have a cross-section?

RE: Jan Hermkens B17
 

There is no real detail on the side view of the formers. However, I like your suggestion of a sandwich. That seems like a good way to go. I have built many kits over the years, but this will be my first scratch build from plans only. I never had any problems with lite ply in any of my planes, so I'm not afraid to use it on this project. It would be cheaper and faster than making the balsa ply sandwich. It is a very light airframe, and will fly on four .40 size 2 strokes. I plan on building it as a sport scale.....covering instead of glass, and no cockpit or interior detail. I want to keep it as light as possible. The big deal is the Robarts...400.00 !!! Been studying the plans for some time now. They are well drawn and clear. I will be relying on my past kit experience, and advise from all you fine folks. As Im sure I will need alot of both for this build to be successful.

RE: Jan Hermkens B17
 

Hi Guys,

Balsa Ply is a real ply, but only from Balsa (3 cross Layers), 3mm (3x 1mm ) or 4mm (2x1mm +1x 2mm) thickness.
This Balsaply (Balsasperholz) I have made it in the past myself, but now is available over here, especially in Germany even in more Thicknesses;
For example http://www.heerdegen-balsaholz.de/home_ger.htm (look for Balsasperholz) , and some others.

Balsa ply is even much lighter than Lite-Ply (poppler-ply), but even stronger.
I did not know it is so hard to get it in the USA.
And with a B-17 model it is very Important to save each gramme behind the CG, because the ratio nose/tail to the CG ist 1:3, (most models have 1:2)

Kind regards,
Jan

RE: Jan Hermkens B17
 

Thanks Jan for clearing up my question on the balsa ply. Now I can start ordering materials and get this project started ! The other question I had was the fabrication of the clear plastic nose dome and top turret. Since I am a yacht builder, I understand the plug and mold process. Can you tell me what material and thickness you used, and also at what temp you baked in the oven and for how long. Perhaps you could elaborate a little on that process, and how you were able to achieve such fine results on your model. I was looking on your website pics and saw your wood plugs.

RE: Jan Hermkens B17
 

Hi Jeff,

Cowlings,Turrets and Retracts;
The cowlings are made from aluminium stove pipe with a 3mm plywood former half glued in. To these formers the radial motor-dummies were glued, and then over these rings a polyester GRP moulded nose cowl ring.
In the aluminium pipe, cooling gills were slotted and bent out a little bit.
Upper turret, nose cone and cheek gun shields were formed, with plugs, from 1mm clear PVC in the kitchen stove (200°C). The clear PVC is pinned on a bottomplate with an opening 0,5mm larger all around than the plugbottom. Keep an eye on it, and at the moment the clear PVC is sagging very well, take the whole out of the stove and push the plug through. Cool it down with a moisty cloth and take out the plug.
Chin, Sperryball and tail turret were made from polyester GRP, on mouldings, with the help of big balloons (blown up) pushed over the mouldings.

kind regards,
Jan

RE: Jan Hermkens B17
 

Thanks again Jan ! This pocess seems very easy. all the labor will be in making the plugs. I have my material list for the fuselage ready, and plan to order the lumber at the end of this week. All thats left now is to take the plans down to the print shop and make a few copies, and I'll be ready to get started....can't wait ! Former F-6 that supports the aft wing tube calls for 4mm lite ply. Unfortunatly, all the suppliers here only stock lite ply in 1/8" or 1/4". So for that former I plan to laminate 1/16 birch and 1/8 lite ply together to get 3/16.

RE: Jan Hermkens B17
 

Just finished my Jan Hermkins B17 cant wait till spring to test fly it..I looked a wingspan models prices and parts wow over priced..and had problems getting a couple of their scale parts not really happy with them at the moment...

RE: Jan Hermkens B17
 

Just finished my Jan Hermkins B17 cant wait till spring to test fly it..I looked a wingspan models prices and parts wow over priced..and had problems getting a couple of their scale parts not really happy with them at the moment...For my cowls since im not a pro builder I went to fiberglass specialtys and they also have a top fiberglass deck that fit nice wow what a time saver..But i did use the 1/9 top deck tourett from wingspan models and it fit good.Since im not familliar with big aircraft with so many servos i used 2 receivers 1 for each side.is this common? hope so because i got wires everywhere!!...

RE: Jan Hermkens B17
 

Did anyone build the Jan Hermkins b17? this winter? I would like to talk about a couple things...

Thanks for the great tip on eliminating lite ply. I will use the balsa laminate idea from here on out. I built the Jan hermkens B17 and it fly's so smooth . However I did veer from the plans on the wings and decided to use a wing tube for removal..

I did build this B17 from Jan Hermkens plans. If you are still building feel free to contact me Kenny..

The Robart gear fits in tight! I am using 4, four stroke 91s because mine was a little heavier than I hoped and I figured I could always cut back on power if needed. I also bought my cowels from Fiberglass Specialties as well as the top deck..

did you ever build the jan hermkens b17? just curious..Kenny..

I have updated my plans of my large Scale models in 2010; 1/10th B-17 (125”), 1/10th Short Sunderland (136”), 1/6,6th P-61 Black Widow.
a.o.t., I changed the joiners into Alum. Tubes & Carbon tubes.

I sell these updated plans now myself, other Vendors (legal &ilegal) are selling my old plans!

In this moment I am building a large A-26B Invader (1/5,9th=142”), also from own plan, the plan will available in 2015, when the model is ready and had her maidenflight.
Have a look on my homepage; www.janhermkens.nl
Kind regards,
Jan Hermkens
Netherlands

Thanks for the reply.. Although im not a pro builder your plans worked good for me. I will buy the updated plans when available please keep me informed as to when and where to get these. kenny

Jan, I have looked at your site and do not see any price list on the B17 plans or anything you have? Could you send me some information on your plans, parts or anything you have to offer? I would like to build another B17.. [email protected]

Just to let folks know. I do not consider myself as a pro builder but the Jan Hermkens B17 was a Great first time bomber build and he is right about keeping the weight down behind the C G as I had to add weight in the nose. I placed it in the chin turret. I followed the plans and with the exception of using aluminum tubes for the wings this thing flew soo smooth! It will fly like a trainer when balanced right. I am an average builder and get just as intimidated with giant projects like the next guy! In comparison to other Bomber plans/kits an average guy can build this far less expensive than what ive seen out there. Fiberglass specialty's has some things that will fit these plans but you will need to modify only the nose just a little bit "no big deal" I also got mu Cowell's from them. If any one decides to take on the project I am willing to tell you what worked for me. Also Jan himself is a very kind and helpful guy I'm Shure he will answer any questions for you as well... Good luck and God Bless fella's....

Hello.

Here is a video of my Hemken B-17 that i built back in 1988. It was a great flying bird. Hundreds of flight until a freinds P-51 hit my tail an shoot me down.
https://www.youtube.com/watch?v=_47KWY9Hzy8&list=FLrtKS5VvBY9dklH6RocxqsA& ind

Ivan / Sweden

Hi Ivan, just read your message. Yes I did build the Jan Hermkens B17 125" wing. I made a couple of improvements to mine. I used aluminum tubes to attach the wings and found that fiberglass specialties had a top deck that fit with a little adjustment in the nose area. Jan has upgraded his plans and I just received them he also went to tubes for the wings, I plan on building another one..I saw your video and it looks pretty windy during your flight. My B 17 flys more stable than your video shows of yours. You did a great job building that bird and it really looked nice....kenny

Hello Kenny.

Like you said, it was a very windy day. Otherwise the model was very stable to fly.

Now i have an other B-17, same scale 1/10. Built from a laser cut shortkit. German producer, don`t remember his name. I have gone all electric and it is a delight to fly as you can se in the videos if you scroll all down.

https://onedrive.live.com/?cid=448F87E27B619773&id=448F87E27B61977 Ivan.

B 17
 

Did you use Jan Hermkens plans? If not which plans did you use on this?

Hello Kenny.

This is completely different plans. You can`t compare this to Hemkens. Realy fantastic plans, allmost 100% scale, even the the wing profile is scale.

The Designer is CH-DAVIES-GARNER. I don`t think he is making this kits no more.

www.cdscaledesigns.com

Regards / Ivan

PS. I still have the plans. If you are intressted you kan have them for free if you pay the shipping.

If i remember right there is 5 or 6 plans plus building instructions.