Jump to content

DB RICHTHOFEN - A Kit To Be Completed


Nigel Grant 1
 Share

Recommended Posts

This picture appeared in our club newsletter a while ago with an invitation for anyone who was interested to take over this part-built kit which had spent time in several other people’s attic and was needing someone to complete it. No one else wanted it so I brought it home from our next club meeting.

I enjoy building, as much as flying so I am interested in finishing it off. I already have some red film and a Saito 56. I don’t have much building space at the moment to get on with the build but there are a few things that need to be to planned for and get sorted out in the meantime. I’m hoping for a bit of advice from the forum. It was designed as a companion for the DB Mannock and I expect the set up would be similar.

 

image.png.50180fa2277ea3bbc2fbdbc9f0f400ca.png

Link to comment
Share on other sites

You can see the kit box has had some silverfish residing in it at some stage and they’ve spent a bit of time on digesting the instructions, but fortunately the plan was a bit more of the challenge to them. It shows the model built and set up like a big free flight model with plenty of dihedral, top wing incidence and engine downthrust. What’s left of the instructions suggests that the dihedral for the top wing can be reduced to a minimum and incidence set to zero and ailerons built into one or other of the wings. It is the top wings which haven’t been joined yet. The motor is mounted on a paxolin plate (which is not in the kit) and inverted.

What I’m interested in is –

·         Would ailerons in the bottom wing only be OK for a model like this for a bit of sports flying?

·         With the wing incidence reduced to zero, could I also remove the downthrust?

·         Also, reduce the side thrust to 2deg

·         Would it be better to do away with the engine mounting plate and use a bulkhead mount which would attach to the second former back, to allow for the longer four stroke?

 

image.png.ca633f57a5cf2771a9fba53b2cf393f0.png

Link to comment
Share on other sites

This picture shows the motor in place with a factory mount and a 12” prop set at the plans 5 deg downthrust. As well as pulling the plane down under power the prop would look to be at an unusual angle to the line of the fuselage and front of the cowl. I note on Cymaz’s Mighty Mannock the thrust line appears to be neutral and the prop in line with the front of the cowl.

I have purchased the Saito engine mount via RCJapan and it is for the 56 up to the 82. Very nice bit of kit but I was surprised at the weight. 100gms which is almost a quarter of the engine weight. Might see if I can get plastic one from SLEC or JE’s.

 

image.png.17a9a7565ea67db5b294a3a2660f0403.png

Link to comment
Share on other sites

       When I first had my Major Mannock many years ago it was set up just like a free flight model with regards engine thrust line with a heap of down thrust and some right thrust. With radio control such extremes are not needed as we have a throttle and can control flight direction with the control surfaces.  I now have about 2 degrees down thrust and no side thrust. Engine is Enya 904c

               Aileron's on mine are only on the lower wing, they are barn doors but not very effective due to wing having been built [ not by me ] with original dihedral. Also there is no aileron differential, same up and down due to it having been built that way with only one central servo working them. [ Still like this today ]

    On aircraft like this rudder is the primary steering control, mine fly's well using just the rudder but best is to use both controls at the same time.

      As you want it for sport flying build with reduced thrust lines as above, ailerons only on bottom wing for simplicity and a probably with a servo for both and a good dose of differential more up than down movement. 

  Top wing dihedral could be reduced a bit but don't build it flat, it would look silly.

    You may as well keep the engine mount than likely end up adding lead in the nose. Plenty of wing to carry the weight with these models.  Ask away if you want more info. Cheers, John.

         

SAM_0359.JPG

image1.jpg

Link to comment
Share on other sites

Thanks for the advice John. Good point about using the alloy Saito mount as it will help with balancing. Also, about leaving some dihedral on the top wing. A flat wing can appear to be drooping, especially on a biplane where the bottom wing has plenty of dihedral. The instructions suggest 1/2” which should do the trick.

Link to comment
Share on other sites

There were no wheels in the kit and the plan called for vintage style wheels at 4.3/8”. When I first looked on line it didn’t seem they were very available, and Du Bro weren’t listing them as available. I was pleased to find a retailer in NZ selling 1/6th Du Bro’s – discounted as well. But I am a bit surprised at the bulk and weight of them. I’m more used to standard 21/2” lo bounce Du Bros. These seem like small cart wheels and weigh 150 gms for the pair. Should set the model off nicely though.

image.png.5436feed059995ea64bda0bdde52d391.png

Link to comment
Share on other sites

One thing I would appreciate advice on John is how the axle is attached to the wire undercarriage. Appears the axle retainer creates a loop that the axle can “float “up and down in.  Then rubber bands are used to hold the axle down. The instructions suggest this by saying the undercarriage is “of a double shock absorbing type with a scale bungee mounting for the axle and the front undercarriage leg retained with rubber bands. Thin rubber bands being wrapped around the axle and its retainer”.

Your photos on the Mighty Mannock thread, which is a very good read, shows the undercarriage of your model but I can’t quite make out the detail of whether the axle is retained in the same manner as shown on the Richthofen plan. Would you be able to do a close up of how the axle is retained on your model?

image.png.fb11ba0e483e4b64cd66d89400d66c32.png

Link to comment
Share on other sites

Hi Nigel, I built a Mannock from a DB kit powered by a Merco 61 back in the day. As ever when I build from a kit or plan I made a number of mods. Some of the mods were simply cosmetic as I wanted it to resemble a typical German LFG Roland biplane. I mounted the engine with zero-zero thrust offsets, reduced dihedral with ailerons on top & bottom wings also the wheeled undercarriage was interchangeable with floats. Each pair of wings were peg and 2 bolt fixed, a single servo mounted on the lower wing served all four ailerons.  

The sprung axle worked so well that I later copied a version of it to use on my Flair Magnattila. I found that suitably sized "O" rings worked just as well elastic bands but were more durable.

Not too long after I built the Mannock I was on a model flying week holiday organised by RCM&E. I met David Boddington (in the bar)one evening & mentioned that the Mannock plan had no cg shown. Turned out that I had an early version kit but this led to a discussion on, amongst other things, why David's models often had large downthrust angles. The basic reason boiled down to his models being designed to be flown by pilots with a range  of abilities from the relative novice up. Which meant a fairly forward cg with wing/tailplane incidences to cater for this, leading to the use of generous engine downthrust angle. This use of downthrust was/is a legacy from FF & single channel days when it was a means of automatically limiting any tendency for the nose to pitch up with too much power.  But of course good throttle control effectively eliminates this need for downthrust.   

 

Here's a couple of photos of my Mannock on floats & close ups of my Magnattila U/C.

 

804087293_Mannock_floats_1.jpg.9ff8541e70a54b1362d8d889cd6c1c62.jpg

Mannock_floats_2.jpg.8368d939c5c41b918f2cffd0c1503ab0.jpg

 

PICT0268.thumb.JPG.958ef59848397f2db268a696894978ca.JPGPICT0267.thumb.JPG.e8bd55fb359b7ae913da6373a3088b53.JPG

Excuse the rough untidy appearance they were taken during the model's refurb & conversion from many years of ic power to more civilised clean electric power.   

 

Also, don't know if it's any help but I've attached a pdf file I made of the Mannocks  building instructions.Mannock Manual.pdf

   

Edited by PatMc
  • Like 1
Link to comment
Share on other sites

Hi Nigel, the system I use is a little different from those above in that it allows some rearward movement as well as upward movement. First pic is of Mannock UC with bungy second without.  You can see there is an oval loop in the rear UC leg where the axle is free to travel.

A bungy cord loop goes from the one hook on the front leg around axle and back to the hook a couple of times.

Pic 3 is UC for refurb of Flair Bristol F2b I am working on and works in a similar way. John. Both aircraft weigh 13/14 lbs so some suspension is desirable. Hope this helps. John.

mannock uc1.JPG

mannock uc2.JPG

Bristol UC.JPG

Link to comment
Share on other sites

Thanks very much Pat and John for the pictures of how the undercarriage is set up. It all makes good sense now and is obviously a tried-and-true method. I do have a wire bender but that’s a good tip about using the nails in a decent block of wood.

Really appreciate the instructions for the Mannock Pat. The ones I have for the Richthofen did not have the sections on-

·         Interplane struts,

·         Finishing,

·         Rigging, or

·         Flying

I wonder if the final page with those sections was missing. Has explained more and the introduction has further detail as well. The instructions I have say the kit was manufactured and distributed by Micro Mold, which I’m sure David Boddington was involved with.

Link to comment
Share on other sites

  • 10 months later...

Good way to make a start on this was to set up the center section of the lower wing to take a SLEC bomb. Decided it was a good addition as the granddaughters were here the other day and had great fun out at the field with another plane I have one fitted to. Bit of a fiddly job but looks like it will work out alright. Will be a good accessory on the finished item I hope. It means the bottom wing will have to be held on by a front dowel and wing bolts.

 

20220612_162415.jpg

20220612_162644.jpg

Link to comment
Share on other sites

 My Major Mannock has twin bomb carrier's [ just visible in pic above ] worked off one servo and 3 position switch on transmitter so bombs released in sequence.  Getting them anywhere near the target difficult to say the least.:classic_biggrin:

Link to comment
Share on other sites

  • 2 weeks later...

Finished detailing the center section with ply mounts for the bomb release and its servo. Also an aluminum tube to hold the 6mm wing locating dowel with a couple of extra riblets. I have sheeted the whole center section which involved paring 1/16th inch off the ribs and cutting the sheeting between the spars and leading/trailing edge. All stuff that wasn't on the original plan which was just nylon covered and banded on. After I have started the fuselage and fitted the ply plate with the T nuts to take the wing bolts I'll drill holes for the bolts through the trailing edge. The plate will have to be located carefully so the bolt holes don't end up up going through the rear dihedral brace. 

20220626_132500.jpg

Link to comment
Share on other sites

I have pretty much finished off the bottom wing now by adding sheeting to the top of the leading edge and also webbing between the spars. Has stiffened up the wing a bit which has allowed me to correct the wash-in that was in the surfaces. Also hoping it will make covering a bit easier as I am planning on using HK translucent red which I understand has a high shrinkage rate if too much heat is applied. As in my last post, fitting the sheeting required paring a bit off the ribs back to the main spar and cutting the sheeting in. I have tried to use reasonably light balsa as I am aware all the extra detailing is adding on weight and I am planning on building in ailerons to the top wing also.

It is tempting to cover the wing to see what the translucent film is like to use but I think it is proper to finish the whole aircraft first so I can get a "bare bones" photo of it.

20220626_194855.jpg

  • Like 2
Link to comment
Share on other sites

I am going to put ailerons into the top wings using the outer three rib bays and the tip as suggested in the instructions. Often for a biplane with just one set of ailerons they are on the bottom wing but that wing had already been joined and running tubes for the servo leads would have been tricky and it has a bit of dihedral as well. I will join the top wing with just 1/2" under each tip which is what is recommended in the kit instructions for the aileron version. I have found the scale plans for a Fokker D6, which this kit seems to be close to, that has this configuration of ailerons. The D6 is essentially a radial version of the D7 which was the much more prevalent version. 

 

https://outerzone.co.uk/plan_details.asp?ID=2305

 

To drive the ailerons I am going to need a servo out in each wing and normally I like to run the servo lead, with an extension in this case, in a rolled paper tube. The tube is 15mm dia which of course is the diameter of the Dremel sanding drum. Normally a hole this size doesn't seem to matter in a deep symmetrical wing with capstrips reinforcing it. But in this case there are no cap strips and the rib where the tube will pass, behind the front spars is only 35mm, leaving 10mm of 2.5mm balsa above and below the servo lead hole. I am concerned this will weaken the wing and so I am thinking that I will glue in a series of riblets to strengthen the area. I hope the photo below shows what I'm intending as well as the size and the position of the hole. 

Of course I will precut the holes in the riblets and to form the ones in the ribs that are already glued in place I will use the 90deg attachment for the Dremel. As Peter Miller has said in other threads, you don't often use it but it sure is handy when you need to.   

20220702_204157.jpg

Link to comment
Share on other sites

 By riblets [  short ribs between the main ribs in the leading edge to maintain a better profile ] and going by your pic I recon you mean short doublers where the paper tube goes through the ribs will be good, also the paper tube itself will add strength glued to the ribs.  The doublers perhaps should be cross grain to the ribs for max strength.  John.

Link to comment
Share on other sites

Thanks John and yes you are right. They are doublers as of course riblets are spaced between the main ribs. I have also made the same incorrect reference on 26 June where I am using a partial rib either side of the main one to support the wing locating dowel.

I'll get on today and make a ply template as there will be a few to cut out. I've got some time today as although it wouldn't of been a bad day for a fly down here in Christchurch NZ, I am recovering from a head cold. New Zealand has been fairly isolated for a couple of years and now the borders are open and there are less internal lockdown restrictions, quite a few colds and flu's are circulating around in addition to COVID, which I've avoided so far.

Link to comment
Share on other sites

  • 2 months later...

Haven't had much spare time lately but was a nice day to be in the garage today so did some work on making the trays for the aileron servo's and the tabs for them to attach them to the wing. Even though this kit is old and has belonged to a few others I have made it my own now by slicing my finger this afternoon with the good old pro edge 11 and leaving my "mark" on the frame work!

20220903_154725.jpg

  • Like 1
Link to comment
Share on other sites

  • 4 weeks later...

Needed to make up the strut hooks for the wings and thought it would be a bit of a fiddly job bending piano wire into small shapes. That was until I realised they are the same depth as my  Z bend pliers makes. It was a very quick job to make up a batch and always fun trimming the piano wire to length with the Dremel

 

 

 

20221001_164455.thumb.jpg.94e052414d0a0add742d08fc69470910.jpg

  • Like 1
Link to comment
Share on other sites

  • 1 month later...

The top wing is finished now. I don't think there's anything else that I can glue onto it so it is time to start thinking about the fuselage. I have noticed that the ribs that have been assembled into the wing are a bit different to the plan. They are, about 4mm deeper and therefore the wing is thicker. The center section is a bit narrower. The wing's are not quite flat bottomed and has a bit of shape from the spar forward. I will need to draw and cut new 6mm sheeting and doubler's to hold the bottom wing in place. The original design had positive incidence for the top wing but says to reduce it to 0deg if using ailerons. The plan shows the bottom wing would also have some positive incidence but since I will have to draw and cut new sides and doubler's I expect I might as well set that to zero as well?

20221126_212252.jpg

Link to comment
Share on other sites

  I wonder if your model is of later production. My Mannock's wings are flat bottomed. 

Not ever checked the incidence of my model just flown as is.

However the more or less standard for aircraft of the WW1 era is for the top wing to have 1 1/2 degrees less incidence than the lower wing.  This helped reduce the drag of biplane interference in a time when engine power/weight ratio was low. The tail incidence is usually set the same as the lower wing but on some types tail incidence could be adjusted by the pilot.

   Engine was normally set at about 3 degrees down which is how I have my Mannock,  When obtained it had the downthrust of a free flight model biplane of 6/7 degrees which just looked daft and is not needed for an RC model where we have elevator control.

large.427198897_lmfcflyin2010g.jpg.fcda8af8f756a9edd87ae6aad1a54cae.jpg

Link to comment
Share on other sites

What a great photo John! It encourages me to keep moving with my project. Yes those wings are flat bottomed. I'll follow your advice and leave a touch of incidence on the bottom wing. I am going to use screwed on nylon horns for the ailerons. I had wanted to form the control horns the same as yours using 1.5mm glass fibre sheet but couldn't find any down here. One of the hobby guys suggested I make my own sheet between a couple of pieces of glass.

 

Link to comment
Share on other sites

  The control horns on mine are Paxolin plate, the sort of stuff used in old radio boards for component mounting.

   Club member took the pic a few years ago while I was still on 35meg. Now on 2.4

    If you are wondering about the red bit's underneath, they are Bomb rack's for extra fun.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...