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Gee Bee Model D

Coverite Kit

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Erfolg17/04/2017 17:15:55
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10849 forum posts
1033 photos

I am starting the build of a Coverite Gee Bee Model D, it has been waiting some 20, maybe 30 years to arrive at the top of the "to do" list.

Looking on the front label it promises that it can be built in 10 hours. Of course that is not with me doing the build. I well remember BEB chiding me that a Greenacres Mass Build could be done in a month. Whereas i was thinking along the lines of 3 months. After this time I am talking a very ordinary build and finish. So 10 hours, well, no. Ten days, probably not. Now ten months, that is do able.

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The front label with the claim.

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Although the box has been shut for many, many years, the plan has deteriorated. It is not so much a plan, rather a sketch, as the more you look, the more is missing. A plan view immediately is obvious.

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The part list does look brief though. The contents does come with two rolls of Coverite. At present, I do not know if it is an iron on fabric.

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The box is rather crammed full, for a kit with so few parts.wp_20170416_13_31_49_pro.jpg

The whole lot weighs in at 2.2kg which is pretty much 5 lb. On that basis the very least power needed is 500w. where as 750 will be the target.

My usual question at this point has anybody any experience of this kit or the model?

Erfolg18/04/2017 11:04:23
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10849 forum posts
1033 photos

It is perhaps worth mentioning what a Gee Bee model D was. It was one of the early aircraft built by the Gee Bee company, as the "D" indicates. Conceived as a sports plane, before becoming better known as a Racing aircraft. The record was pretty good, as were subsequent models. Designed by Bob Hall whose obituary is worth reading. Although often presented as being designed by hick farmers who knew nothing, that is a long way from the truth. Their real problem was that the company operated during the depression. To keep in business, they went racing, becoming more reliant on this activity. Nothing guarantees accidents, like pushing at the limits. Even when compared with many UK companies, most aircraft and types in that era, ended their days after an accident, although not witnessed in such spectacular manners by so many people.

Erfolg30/04/2017 20:29:19
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10849 forum posts
1033 photos

I have made a little progress with the kit, although I have ground to a halt, again.

I am less than convinced with the instructions, there brevity disguises the complexity and unanswered or addressed issues.

The instructions suggest a method where the model is essentially initially built in the hand. At first it went well, until the second side was to be attached. Then I found that I could not get a true fuz. So I got my jig out and used it.

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I also aded some renforcemnets to the gormers, as they seemed a little weak.

The nect stage is to add a rolled top,. although the instructions indicate this can be done with a flat sheet. An initial try indicated it would not happen with me. So I resorted to pre bending. I used a rum and a plastic PVA bottle.

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Offering the shells to the fuz, indicate an issue around the cock pit, again the instructions , nor the drawing help. I have now stopped to decide what to do.

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In this area I have added a couple of local formers to support the skinning, as I find that you cannot have skins wafting about at either end without support.

I will be tidying up the work bench, when i have all the repairs and adjustments completed on my present flying model fleet.

Erfolg02/05/2017 19:44:51
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10849 forum posts
1033 photos

Although very doubtful of the method used by Coverite to form the turtle deck, it works very well. That is inspite of my lack of skill.

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The latest bit of nuisance is that only having a side elevation, from the information supplied, it has been difficult to establish the true shape of the cockpit. I have been on Goggle, looked at the photographs to try and get a good impression of the shape. On the model d it does seem to be very narrow, where as the "X" was big, the "C" narrower still.

Erfolg06/05/2017 13:19:28
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10849 forum posts
1033 photos

 

I have done a bit more, inspite of the documentation, the drawing is not complete, I guess a small fraction of the Henry Haffke original, and the brevity of the text, is astounding in its omissions.

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For the moment I think that is all I can do on the body.

Now onto the left hand wing panel, as that is the only one provided. I will have to think how to set about the RH panel.

I will attempt a clear up before starting. Part of the problem is that I have run out of storage racks for my completed models. On that basis my smaller models and frequently  flown models are now stacked around the room perimeter.

Edited By Erfolg on 06/05/2017 13:21:48

Martin Harris06/05/2017 13:28:35
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7566 forum posts
188 photos

The paraffin trick worked really well for me with a plan supplied with just one side detailed. Turn the plan over, rub paraffin gently over the plan and the details come through like magic. After a few days it dried out and left the paper looking and feeling quite normal.

Just make sure you complete the framing up within a day or two!

Bearing in mind the age and possible frailty of the paper, it might be best to try a test first!

Erfolg06/05/2017 16:31:43
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10849 forum posts
1033 photos

Martin

Not having any paraffin, I will try Methylated Spirts on a corner to see if that works.

Does any one have experience of meths, or other post Paraffin fluids?

Geoff Sleath06/05/2017 17:40:28
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2610 forum posts
198 photos

Staples in Derby copy plans and I've found them very helpful. Presumably other branches also have drawing copy facilities. Perhaps they could do you a mirror image which would make the drawing OK for the other wing?

It certainly doesn't look like a very quick build to me, either, but then, I'm also pretty slow and take breaks which adds to the total build-time. Is the span 56"? If so, it isn't a very small model either but the right size for an every day model IMO. How are you going to power it?

Geoff

Zoe Garland06/05/2017 17:42:02
3 forum posts

that looks awesome why not make it in 3d printing

Erfolg06/05/2017 18:17:50
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10849 forum posts
1033 photos

Geoff, there is only one way, is there not, and that is electric.

So I do not have to take the wing of to arm the model i am thinking of making the head of the pilot an arming plug. In a similar way as to my FW 190 D

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or on the D version

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PatMc06/05/2017 18:20:52
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3687 forum posts
476 photos

Erf, you can download a copy of the original Henty Haffke plan plus the July 1978 Flying Models article, which includes building instructions and info on 9 of the full size aircraft, from here.

The plan is in .pdf format which can be printed by most copy shops.

Outrunner06/05/2017 19:23:58
10 forum posts
Posted by PatMc on 06/05/2017 18:20:52:

Erf, you can download a copy of the original Henty Haffke plan plus the July 1978 Flying Models article, which includes building instructions and info on 9 of the full size aircraft, from here.

The plan is in .pdf format which can be printed by most copy shops.

You can tile print a .pdf plan and stick together to build a full size drawing, no need to go down to the copy shop.

Phil.

will -006/05/2017 21:34:38
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448 forum posts

watchin with interest as I have one in my queue too

Erfolg08/05/2017 11:56:54
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10849 forum posts
1033 photos

Patmac, the link is really good. There are small differences between the kit and the original drawing. It does surplice me that there is not a plan view. Or at least a part view onto the cockpit area. It is interesting that Henry also found difficulty in obtaining pictures of the aircraft, which pretty much is still the case.

The most obvious is that the kit makes use of a full length side pieces, which have the solid balsa fore side pieces. I guess that Henry used a different, lighter, but more difficult route to set up the back end.

The second and third differences is that the kit uses polystyrene vacuum mouldings for both the front cowl and the UC.

Erfolg14/05/2017 16:33:23
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10849 forum posts
1033 photos

The method used to build the wing is pretty much a first for me, although there are some similarities with the "Sterling PT19" kit. The two spars are used as a jig, which requires the ribs to carefully eased to obtain a sliding fit. As made the fit is an interference, possibly a transition, although to much force is required to slide them down the spars.

Once the fit was obtained, i found there were very slight variations across the edges. These were removed to produce a pack of ribs.

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I then packed the spars to make them parallel to the board, also ensuring that the bottom is clear. The spars are the only reference as the section is a semi symmetrical, without any setting tabs.

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Having assembled mostly one wing, i will now need a day when my better half is out all day. I need a long table to set up the second spars, whilst ensuring that the built wing remains in the same plane. Not like a propeller. The final issue is ensuring the correct dihedral. This set of operations has to be spot on, if the send wing is to go together well.

I defiantly could not build this model in 10 hours, never mind the suggested 8 hours.

Erfolg15/05/2017 14:07:10
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10849 forum posts
1033 photos

I have managed two very important tasks this morning.

The first could have been disastrous, potentially requiring hospital attention. Whilst my wife was out at golf this morning, I set up the wing with the spars, clamps, spacers, weights and setting gauge on the dining room table. I then went out did the weekly shop for groceries and returned home. OMG, there was a white car sitting in the drive. The golf match had been cancelled, due to the rain. Whilst She who must be obeyed attention was else where, I sprinted into the dining room, scooped up every thing, returning all the items to the modelling room. Obviously she had no need or desire to go into the dining room. That was one hospital visit avoided due to sever ear damage.

The second was a consequence of my learning to read, which i have recently achieved. The kits instruction sheet, suggested that the plan be turned over. This I did, to find I could just make out the lines on the other side. Rather than trying to see the lines whilst building, I decided to pencil them in, whilst it was relatively easy to see them. Which i have done.

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Erfolg17/05/2017 13:34:14
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10849 forum posts
1033 photos

Another basic step taken. Possibly 2/3rd or 1/2 the wing has been done.

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In many ways the design of the wing spars grate with me. The spars not being on the extremities of the wing profile do not fit well with my training. Yet I do acknowledge, that to really build a lighter spar arrangement for similar strength, requires a lot of work. As without the shear webs keeping the spars apart, it would be weaker almost certainly and the parallel axis theorem would not be applicable.

The other probably more important aspect from the Coverites point of view, the central spars, although incredibly beefy, act as a wing jig, making it more probable that a good wing is built.

My farther used to point out, that "Beam Theory" only holds true when the beam accords to all the stipulations and caveats of the theory, which is never true in the real world. That the bits that are fastened on, will act as points of stress concentration, just to the side. As long as the beam is theoretically capable of carrying the loads, it will still do so, you just now know where the beam will probably fail.

So all in all, although, as a purist i wince, as a pragmatist, I think, it probably matters little.

Perhaps what matters more, do the UC blocks and supporting structures look like they can cope with the rough and tumble of my landings.

Oh, the next step is a clean up of the work area, as it is cluttered, and dusty.

Edited By Erfolg on 17/05/2017 13:37:05

Erfolg19/05/2017 16:42:37
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10849 forum posts
1033 photos

The promised clean up has not really happened, a partial, could be claimed. What stopped me, well that heart stopping moment when you realise all is not well.

In my case it was offering the wing to the body, when I realised the two did not mate, or should that be fit, or what ever phrase you prefer. A careful measuring of the bits against the plan suggested that the max error was 1/32", yet all appeared to be out up to 1/8". In the end i concluded that the drawing, was not quite as accurate as i would have liked.

What to do? i decided that an extra partial bulkhead was the solution on the underside, I could then cut of the top of the original one, then be able to use it as part of the underbelly fairing.

It is now very apparent that this kit is most defiantly not aimed at the novice. Quite a contrast with the Sterling Kits, step by step instructions, with a model far more complex to build, although with the view it could well be built as a first model. This is most apparent in that the under fairing, is not mentioned by Coverite, Nor is the method of bolting the wing on, certainly not in any detail. The list of what is not mentioned would take pages of A4.

I now find myself in the position that reference to the Coverite instructions is even less likely, as it is apparent thet they thought that to build the model you would have your preferd methods.

Still like the kit though.

Erfolg19/05/2017 18:46:06
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10849 forum posts
1033 photos

With a former (partially) repositioned , the wing fits, although not finally.

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I will now concentrate on sheeting the parts of the wing to be covered and where the wing servos will go.

I am a little happier, although I have little understanding of the full size aircraft. I think it is partially because i like to sheet all the wing, or at least the leading edge area. If this were to increase scale fidelity, it would be the excuse to start sheeting. Although I know and have seen photographs of the both the Z and R having sheeted play wood wings, it is not necessarily the case with the D.

Erfolg20/05/2017 11:38:09
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10849 forum posts
1033 photos

Having pretty much now plodded through all of the Coverite instruction sheet, I realised that my model was far from complete, although reaching the end of the instructions would suggest otherwise.

However, examining a pile of bits and pieces, plus an instruction to drill a 1.375 deep hole in the LE, then looking at the wing and drawing, I knew, that the designer expected the builder to be experienced enough to sort out a lot of the detail.

On that basis i have reinforced the wing join in the wing centre, with the objective of providing a firm area and distributing the loads and stresses from the wing bolts. The same is true for the area where the wing peg is to go.

I now have the motor, so can start look at its installation.

There is well over 40 hours of work for the relatively detail work to do. Ten hours to build , on whose planet.

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